From ian.g.kelly at gmail.com  Sat Mar  1 00:16:18 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 28 Feb 2014 22:16:18 -0700
Subject: Tuples and immutability
In-Reply-To: <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
Message-ID: <CALwzidkKfEvJ8HxnQKJEzEeNUVQ2WBB40+o_QnkmwP2tBFb3Gg@mail.gmail.com>

On Fri, Feb 28, 2014 at 5:22 PM, Mark H. Harris <harrismh777 at gmail.com> wrote:
> I really think this is a bug; honestly.  IMHO it should be an error to use  +=  with an immutable type and that means not at all.  In other words,  the list should not even be considered, because we're talking about changing a tuple... which should not be changed (nor should its members be changed).

How would you propose doing that?  Bear in mind that while Python
knows that tuples specifically are immutable, it doesn't generally
know whether a type is immutable.  The best it can do is try the
operation and raise a TypeError if it fails.  So you can special-case
the code for += to fail earlier if the left side of the assignment is
an tuple index, but it's not currently possible to do the same for
arbitrary immutable user types.

Even if that is solved, how you do propose preventing the simple workaround:
    tup = (0, [1, 2, 3], 4)
    thelist = tup[1]
    thelist += [5, 6]
which currently works just fine.

I don't think that entirely disallowing mutable objects inside tuples
is an acceptable solution.  For one, it would mean never allowing
instances of custom classes.  They could then basically only contain
strings, numbers, frozensets, and other tuples.  For another, my
experience suggests that if I'm putting a list inside a tuple in the
first place, I am generally not relying on the immutability of that
tuple anyway, so I don't really see this as fixing an actual problem.
The usual reason for wanting an immutable object is to hash it, and a
tuple containing a list already can't be hashed.


From ian.g.kelly at gmail.com  Sat Mar  1 00:26:07 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 28 Feb 2014 22:26:07 -0700
Subject: Tuples and immutability
In-Reply-To: <lerd1m$311j$1@cabale.usenet-fr.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <lerd1m$311j$1@cabale.usenet-fr.net>
Message-ID: <CALwzidnfEgjZqOSL_a0gZ_+G-YEYsNOYL9kuqBMwMCDGNJqtYg@mail.gmail.com>

On Fri, Feb 28, 2014 at 6:27 PM, Eric Jacoboni <eric.jacoboni at gmail.com> wrote:
> Anyway, the TypeError should rollback, not commit the mistake.

The Python interpreter isn't a database.  It can't rollback the object
because the operation that was performed may not be reversible.
Consider for example a socket class where the += operator is
overloaded to send a message on the socket.  The message can't be
unsent.


From harrismh777 at gmail.com  Sat Mar  1 00:30:30 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Fri, 28 Feb 2014 21:30:30 -0800 (PST)
Subject: Can global variable be passed into Python function?
In-Reply-To: <mailman.7495.1393639309.18130.python-list@python.org>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
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 <mailman.7453.1393562612.18130.python-list@python.org>
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Message-ID: <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>

On Friday, February 28, 2014 8:01:45 PM UTC-6, Chris Angelico wrote:


> 
> Does your switch construct have to handle the magic of GT_1 meaning ">
> 1", or do you first figure out where it falls with an if/elif tree?

> ChrisA

hi Chris,   yeah... well think again of the switch block in C...   the switch block selects a branch based on an integral number (int character) that is generally a return code from a function.  The function hides all of that logic. The function runs and returns a "number" which is passed to the switch block. That number generally corresponds to a DEFINE constant at the top or in the header...   so we get something really readable:

x = somefunc()
switch (x):
  case: CONSTANT1
       call blah blah
  case: CONSTANT2
       call blah blah blah
  default
       blah

This very same concept can work in python code too... if everyone would just agree to try. Again, how it switches is less important than does the "switch" appear readable to humans... whether its optimized or not. 

Its up to the devs whether it switches on an int,  a "switch object" whatever I mean by that, or on something else I have not thought about...   the point is ,

    ... can we make something more readable to average people than large if elif else chains, or dict dispatch tables... ??

    Its just a question.   I know Guido thinks not... and a lot of other people too... but what if there is a third option?   If we think about this hard enough there is probably a win win out there that would work/    

just sayin

marcus

  


From ian.g.kelly at gmail.com  Sat Mar  1 00:34:56 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 28 Feb 2014 22:34:56 -0700
Subject: Tuples and immutability
In-Reply-To: <2ddad91d-e188-4fd0-be1c-ed30edbf280b@googlegroups.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <lerd1m$311j$1@cabale.usenet-fr.net>
 <2ddad91d-e188-4fd0-be1c-ed30edbf280b@googlegroups.com>
Message-ID: <CALwzidk64=CZiMf3969jnwWy9Y6X4O68JhLWTcQ3q7nhfLNaZA@mail.gmail.com>

On Fri, Feb 28, 2014 at 9:45 PM, Mark H. Harris <harrismh777 at gmail.com> wrote:
> I really believe IMHO that the error should have come when you made the list an item of a tuple.  An immutable object should have NO REASON to contain a mutable  object like list... I mean the whole point is to eliminate the overhead of a list ... why would the python interpreter allow you to place a mutable object within an immutable list in the first place.   This is just philosophical, and yes, the core dev's are not going to agree with me on this either.

One very common example of tuples containing lists is when lists are
passed to any function that accepts *args, because the extra arguments
are passed in a tuple.  A similarly common example is when returning
multiple objects from a function, and one of them happens to be a
list, because again they are returned in a tuple.

    def f(*args):
        print(args)
        return (args[1:])

    >>> result = f(1, 2, 3, [4, 5])
    (1, 2, 3, [4, 5])
    >>> print(result)
    (2, 3, [4, 5])

Both of these things are quite handy, and if you restrict tuples from
containing lists, then you lose both of them (or you switch to lists
and lose the optimization for no good reason).


From harrismh777 at gmail.com  Sat Mar  1 00:50:44 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Fri, 28 Feb 2014 21:50:44 -0800 (PST)
Subject: Tuples and immutability
In-Reply-To: <mailman.7501.1393652140.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <lerd1m$311j$1@cabale.usenet-fr.net>
 <2ddad91d-e188-4fd0-be1c-ed30edbf280b@googlegroups.com>
 <mailman.7501.1393652140.18130.python-list@python.org>
Message-ID: <2c38b941-9f3f-485f-9e97-525f28c5453a@googlegroups.com>

On Friday, February 28, 2014 11:34:56 PM UTC-6, Ian wrote:

> One very common example of tuples containing lists is when lists are
> passed to any function that accepts *args, because the extra arguments
> are passed in a tuple.  A similarly common example is when returning
> multiple objects from a function, and one of them happens to be a
> list, because again they are returned in a tuple.

>     def f(*args):
>         print(args)
>         return (args[1:]
> 
>     >>> result = f(1, 2, 3, [4, 5])
>     (1, 2, 3, [4, 5])
>     >>> print(result)
>     (2, 3, [4, 5])

I agree Ian... good points all.   ... again, I'm not arguing with anyone... just saying that an error (whatever we mean by that) should not half-way-fail....   we are only pointing out the problem... we have not idea what the solution is yet. 

Intuitively everyone can see that there is a problem here...  the debate cannot be answered either because of the inherent design of python (almost all of which we love). So, as they say, what is a mother to do?  ... I mean, some people's kids... 

I don't know how I propose to handle the problem... I think the first step is getting everyone to agree that there IS a problem... then debate how to tackle the solution proposals.

marcus


From harrismh777 at gmail.com  Sat Mar  1 01:16:24 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Fri, 28 Feb 2014 22:16:24 -0800 (PST)
Subject: Tuples and immutability
In-Reply-To: <mailman.7499.1393651028.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
Message-ID: <dc08f190-e4d3-40bc-9fd3-9fa24f757816@googlegroups.com>

On Friday, February 28, 2014 11:16:18 PM UTC-6, Ian wrote:

> How would you propose doing that?  Bear in mind that while Python
> knows that tuples specifically are immutable, it doesn't generally
> know whether a type is immutable.  


hi Ian,   consider the problem... its a "cake" and "eat it too" scenario...   you can't have your cake and eat it too....

This is what I mean...   the error message is telling the user that it cannot do what he has requested, and yet IT DID.  You have one of two scenarios:   1) the message is arbitrarily lying and it really can assign an immutable's item...  (and it did!)  or 2)  It really should NOT assign an immutables item (the message is truth) but the action was "allowed" anyway despite the protocol and accepted policy...  in which case the two scenarios add up to a giant logical inconsistency...  QED   a bug.

There really is no way to get around this from the average user's perspective. And therefore, this is going to come up again and again and again... because coders don't like unexpected logical inconsistencies.

It is not helpful either to explain it away by knowing how the policy works under the covers... the average user of the python language should not have to understand the policy of the underlying substructure... 

1) either they can't assign the list item of an immutable tuple type (and the action is a flaw, say bug

of

2) they really CAN set the immutable's list item type (which it did!) and the message is bogus.


Its one way or the other....  we can't have our cake and eat it too... this is (one way or the other) a bug.

IMHO


From rosuav at gmail.com  Sat Mar  1 01:24:15 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 1 Mar 2014 17:24:15 +1100
Subject: Can global variable be passed into Python function?
In-Reply-To: <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
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 <87iorzf4ro.fsf@elektro.pacujo.net>
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 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
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 <mailman.7495.1393639309.18130.python-list@python.org>
 <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
Message-ID: <CAPTjJmqarrGBjkZobczCH2SAZcbQC7O0UrEoKP1AHBD0Q334eg@mail.gmail.com>

On Sat, Mar 1, 2014 at 4:30 PM, Mark H. Harris <harrismh777 at gmail.com> wrote:
> hi Chris,   yeah... well think again of the switch block in C...   the switch block selects a branch based on an integral number (int character) that is generally a return code from a function.  The function hides all of that logic. The function runs and returns a "number" which is passed to the switch block. That number generally corresponds to a DEFINE constant at the top or in the header...   so we get something really readable:
>
> x = somefunc()
> switch (x):
>   case: CONSTANT1
>        call blah blah
>   case: CONSTANT2
>        call blah blah blah
>   default
>        blah

Okay. So you'd do that to make this more readable. Here's the original:

    if (n**2 < D(1)):
        a = __atan__(n)
    elif (n == D(1)):
        a = gpi/4
    elif (n == D(-1)):
        a = -(gpi/4)
    elif (n < D(-1)):
        a = __atan__Lt_neg1__(n)
    else:
        a = __atan__Gt_1__(n)

Now let's see. Your code doesn't perfectly translate, so I'm having to
guess a bit here.

GT_1 = object()
LT_n1 = object()
IS_1 = object()
IS_n1 = object()
def categorize(n):
    if (n**2 < D(1)):
        return None
    elif (n == D(1)):
        return IS_1
    elif (n == D(-1)):
        return IS_n1
    elif (n < D(-1)):
        return LT_n1
    else:
        return GT_1


   switch categorize(x):
      case GT_1:
          __atan__Gt_1__(x)
# Not sure which you mean, this
      case LT_n1:
         __atan__Lt_neg1__(x)
# or this
      case LT_1:
         __atan__Lt_1__(x)
# So I have both, ish.
      case IS_1:
         a = gpi/4
      case IS_n1:
         a = -gpi/4
      default:
# Presumably this should be a=?
         __atan__(x)


Please copy and paste this, and then edit it so the two actually do
exactly the same thing. And then, if you please [1], explain to me how
the second one is more readable.  It still has the exact same if/elif
tree, because there's no other way to figure out which constant you
should have for the switch; and as well as that, it exhibits an
appalling degree of Soft Coding[2], and it's roughly three times as
much code. If you want to change anything, you potentially have to
edit three places: the list of constants at the top, the condition
function, and the switch.

This can't be your idea of readability. Show me where I'm wrong.

ChrisA

[1] Steven D'Aprano unwittingly quoted HMS Pinafore a few posts back.
I'm now doing it consciously, for I hold that (on the seas) the
expression "if you please" a particularly gentlemanly tone implants.

[2] http://thedailywtf.com/Articles/Soft_Coding.aspx


From rosuav at gmail.com  Sat Mar  1 01:29:44 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 1 Mar 2014 17:29:44 +1100
Subject: Tuples and immutability
In-Reply-To: <dc08f190-e4d3-40bc-9fd3-9fa24f757816@googlegroups.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <dc08f190-e4d3-40bc-9fd3-9fa24f757816@googlegroups.com>
Message-ID: <CAPTjJmoiN_vva2y7wXfSrzyLAOg79bG2srzLFeBrk3Gn7LK-yw@mail.gmail.com>

On Sat, Mar 1, 2014 at 5:16 PM, Mark H. Harris <harrismh777 at gmail.com> wrote:
> This is what I mean...   the error message is telling the user that it cannot do what he has requested, and yet IT DID.  You have one of two scenarios:   1) the message is arbitrarily lying and it really can assign an immutable's item...  (and it did!)  or 2)  It really should NOT assign an immutables item (the message is truth) but the action was "allowed" anyway despite the protocol and accepted policy...  in which case the two scenarios add up to a giant logical inconsistency...  QED   a bug.
>

It did not assign anything. The error was raised because the tuple
rejects item assignment. It's that simple.

The object was mutated before the assignment was attempted.

ChrisA


From harrismh777 at gmail.com  Sat Mar  1 01:25:50 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Fri, 28 Feb 2014 22:25:50 -0800 (PST)
Subject: Tuples and immutability
In-Reply-To: <mailman.7499.1393651028.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
Message-ID: <9ee137b0-3313-41c6-9792-9438ff05038a@googlegroups.com>

On Friday, February 28, 2014 11:16:18 PM UTC-6, Ian wrote:

> How would you propose doing that?  Bear in mind that while Python
> knows that tuples specifically are immutable, it doesn't generally
> know whether a type is immutable.  

I was going to bed, and then thought of the solution.  Allow the action.

Hold the error pending until the action either succeeds or fails for the "item," in this case a list, and then post the error for the tuple depending... this would make the whole mess consistent, and even compatible with the idea of dynamic name and type binding...

So, in other words, the action should be permitted, and actually was allowed, and the message is incorrectly reporting something that for this particular "item" is NOT true. The error message (and timing of same) is the bug  (philosophically).

Under the covers it may be (and probably is) more complicated.

Good night everyone.

Cheers


From as at sci.fi  Sat Mar  1 01:54:45 2014
From: as at sci.fi (Anssi Saari)
Date: Sat, 01 Mar 2014 08:54:45 +0200
Subject: how to install automatically missing modules on a debian-system
References: <7841a394-46ff-4f63-8afc-12b396bb8695@googlegroups.com>
Message-ID: <vg34n3ixvbe.fsf@coffee.modeemi.fi>

hugocoolens <hugocoolens at gmail.com> writes:

> It often happens I start a python-script I wrote some time ago on another
> system and get messages like "module_x is missing". I then perform an apt-cache search module_x, followed by an apt-get install name_of_missing_module.deb
> I was wondering whether someone here has a kind of method which automatically
> looks for the missing modules as debian-packages and offers to install them?

I don't know if there's anything that works with random Python scripts.
I suppose the straightforward Debian way of it would be to package your
script in a .deb package and include the proper dependencies, then apt
would take care of installing those too.

Debian has a wiki page covering the project's Python packaging policy
and how to do it at https://wiki.debian.org/Python/Packaging.


From as at sci.fi  Sat Mar  1 01:55:07 2014
From: as at sci.fi (Anssi Saari)
Date: Sat, 01 Mar 2014 08:55:07 +0200
Subject: extend methods of decimal module
References: <02cdd9c7-aef7-4cc7-a813-cd1c9627ceb4@googlegroups.com>
 <mailman.7160.1392836388.18130.python-list@python.org>
 <94b1962a-0004-4c5b-b484-972a166b88b5@googlegroups.com>
 <CAKJDb-NaZmLysq+2KWgd_f4UPKCk7jdLZkvcCM6ECL5TSAwCRQ@mail.gmail.com>
 <mailman.7165.1392847869.18130.python-list@python.org>
 <55525f2c-fd3a-4927-b642-2dbf5eae7e9b@googlegroups.com>
 <mailman.7432.1393520859.18130.python-list@python.org>
Message-ID: <vg3wqgewgqc.fsf@coffee.modeemi.fi>

Terry Reedy <tjreedy at udel.edu> writes:

> On 2/27/2014 7:07 AM, Mark H. Harris wrote:
>
>> Oh, and one more thing... whoever is doing the work on IDLE these
>> days, nice job!   It is stable, reliable, and just works/
>> appreciate it!
>
> As one of 'them', thank you for the feedback. There are still some
> bugs, but I hit them seldom enough that I am now looking at
> enhancement issues.

I recently watched a presentation by Jessica McKellar of PSF about what
Python needs to stay popular. Other than the obvious bits (difficulties
or limited support of Python on major platforms like Windows and mobile)
the slight lack of perfection in IDLE was mentioned. Specifically the
old blog post titled "The Things I Hate About IDLE That I Wish Someone
Would Fix" at
http://inventwithpython.com/blog/2011/11/29/the-things-i-hate-about-idle-that-i-wish-someone-would-fix/

It lists 17 issues and some more in the comments. Are those things
something that could be considered? Or have maybe been done already? I'm
not an IDLE user so this is mostly an academic interest on my part.


From swdunning at cox.net  Sat Mar  1 01:46:02 2014
From: swdunning at cox.net (Scott W Dunning)
Date: Fri, 28 Feb 2014 23:46:02 -0700
Subject: Help with "Guess the number" script
Message-ID: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>

Hello, i am working on a project for learning python and I?m stuck.  The directions are confusing me.  Please keep in mind I?m very ne to this.  The directions are long so I?ll just add the paragraphs I?m confused about and my code if someone could help me out I?d greatly appreciate it!  Also, we haven?t learned loops yet so just conditional operators and for some reason we can?t use global variables.  


from random import randrange
randrange(1, 101)

from random import seed
seed(129)
    
def print_description():
    print """Welcome to Guess the Number.
    I have seleted a secret number in the range 1 ... 100.
    You must guess the number within 10 tries.
    I will tell you if you ar high or low, and
    I will tell you if you are hot or cold.\n"""
   
def get_guess(guess_number):
    print "(",guess_number,")""Plese enter a guess:"
    current_guess = raw_input()
    return int(guess_number)

def main():
    print_description()
    secret = 50
    current_guess = 1
    get_guess(1)
    if current_guess != secret():
        print "Congratulations you win!!"
   
main()


Here are the instructions I?m having a hard time with and just not sure I?m doing it correctly.  I?m not sure the get_guess function is correct and I?m a little lost with the secret and current_guess variable.

From within the body of the main function, immediately after the call to print description, create variable secret and assign it a random number between 1 and 100, generated using the randrange function. You will need to pass two argument to randrange, what do you think they should be? You should be able to use the python help system or online python documentation to make sure you understand the arguments to randrange.

After the end of the body of the print description function, define a new global function named get guess that takes a single parameter. Name the parameter guess number, because it will hold the index (1, 2, 3, ..., 10) of current guess attempt. Make the function ask the user to enter guess using the raw input function. The function will return the number entered by the user, after it has been converted to an integer.

Return to the main function after the statement that assigned a value to the secret variable. In a new variable named current guess store the result of calling the get guess function with an argument of 1. Run your program to make sure it works correctly.

At the end of the main function, check if the current guess matches the secret. If it matches, print ?Congratulations, you win!?. If it does not, print ?Please play again!? 





Thanks again!!!




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From ben+python at benfinney.id.au  Sat Mar  1 02:33:13 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sat, 01 Mar 2014 18:33:13 +1100
Subject: Help with "Guess the number" script
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
Message-ID: <85y50ul6fa.fsf@benfinney.id.au>

Scott W Dunning <swdunning at cox.net> writes:

> Hello, i am working on a project for learning python and I?m stuck.
> The directions are confusing me.  Please keep in mind I?m very ne to
> this.

Scott, please default to asking these ?covered in a beginner Python
course? questions at the Python tutor forum
<URL:https://mail.python.org/mailman/listinfo/tutor>.

Discussions here are going to assume you've already covered the very
basics, so it's not very suitable for the questions you're asking.

-- 
 \          ?Isn't it enough to see that a garden is beautiful without |
  `\      having to believe that there are fairies at the bottom of it |
_o__)                                             too?? ?Douglas Adams |
Ben Finney



From marko at pacujo.net  Sat Mar  1 05:31:39 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 01 Mar 2014 12:31:39 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
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 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
Message-ID: <874n3irz04.fsf@elektro.pacujo.net>

Ben Finney <ben+python at benfinney.id.au>:

> Since you don't care about identity, only that the objects have
> different values, you should be comparing for equality with ?==?.

Ok, one last attempt.

I need *identifiers*. I could simply define:

   class ABC:
       A = object()
       B = object()
       C = object()

The program would work perfectly.

Except, if it's got a bug. I know self.abc contains either A, B or C,
but which one? Printing out self.abc won't give me any help. I could
print out ABC.A, ABC.B and ABC.C and see which one matches, but that's
cumbersome.

The next variant is to use objects that have names:

   class Symbol:
       def __init__(self, name):
           self.name = name
       def __str__(self):
           return self.name

   class ABC:
       A = Symbol("A")
       B = Symbol("B")
       C = Symbol("C")


The same program still works (and still uses "is" for identity tests,
mind you).

The next realization is that the Symbol class is completely redundant as
any string object would fit the bill. Hence we can reduce the visual
clutter by simply defining:

   class ABC:
       A = "A"
       B = "B"
       C = "C"

The same program still works (and still uses "is" for identity tests,
mind you).


Marko


PS The only remaining redundancy is having to repeat the symbol name in
every assignment. If Python (like Lisp) had a builtin symbol datatype,
you wouldn't have to define anything at all but simply assign something
like this:

    self.abc = $A

where $A would be a symbol.


From marko at pacujo.net  Sat Mar  1 05:39:58 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 01 Mar 2014 12:39:58 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
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 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
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 <531115e1$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ob1qeqe0.fsf@elektro.pacujo.net>
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 <874n3ienhd.fsf@elektro.pacujo.net>
 <53113f1b$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87wqgeqk1t.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> But I'm not sure that there is a good reason to put the class definitions 
> inside the __init__ method. That means every time you create a new 
> StateMachine instance, the classes have to be re-created.
>
> [...]
>
> It will be much more efficient if you pull all the Idle, etc. classes out 
> and make them top-level global classes.
> [...]
> But then the closure over sm won't work...

Precisely.

As for effiency, I don't know if it is more efficient to create ad hoc
classes or ad hoc instances; might be a tossup in CPython.

> Since in this example you've actually got significant behaviour in the
> states, they aren't just symbols, and some sort of solution along
> these lines (whether you use multiple inner classes or not) is
> appropriate.

That inner class solution is an alternative to the symbol approach. In
the absense of a switch statement, the inner class has lots going for
it.


Marko


From ben+python at benfinney.id.au  Sat Mar  1 05:48:40 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sat, 01 Mar 2014 21:48:40 +1100
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
Message-ID: <85ppm6kxdj.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Ben Finney <ben+python at benfinney.id.au>:
>
> > Since you don't care about identity, only that the objects have
> > different values, you should be comparing for equality with ?==?.
>
> Ok, one last attempt.
>
> I need *identifiers*.

And, as you've realised, without an Enum pattern you have the option of
using string *values* ? because it's the values you want to see in error
message output.

The *identity* of the values doesn't matter. Any string of the given
value will work fine.

So don't fool the reader into thinking you actually care about object
identity; don't use ?is? for comparing these values. Use ?==?, since
that's all that matters for getting a value that will work fine.

> The same program still works (and still uses "is" for identity tests,
> mind you).

You have provided no justification for using an identity test. It
confuses the matter by pretending you care about object identity, when
you *do not* as evidenced by all your arguments so far.

The equality operator ?==? is clearer for your purpose, and less
confusing.

-- 
 \      ?[Entrenched media corporations will] maintain the status quo, |
  `\       or die trying. Either is better than actually WORKING for a |
_o__)                  living.? ?ringsnake.livejournal.com, 2007-11-12 |
Ben Finney



From ganesh1pal at gmail.com  Sat Mar  1 06:13:11 2014
From: ganesh1pal at gmail.com (Ganesh Pal)
Date: Sat, 1 Mar 2014 16:43:11 +0530
Subject: Python : parsing the command line options using optparse
In-Reply-To: <CACT3xuXWBQC2s2XxE=Cav+RK78voPjbLA0cWSxL50ekktJZ2cg@mail.gmail.com>
References: <CACT3xuWuV8omgE6oV0PNGfwdf-yrO3KPbjHtu=B+NHNuOhA_Jw@mail.gmail.com>
 <leig4s$ri5$1@ger.gmane.org>
 <CACT3xuUGtsER0B3xwAB2CqQ5Zb=v72w8+DQkaYz681xeSeJ2CQ@mail.gmail.com>
 <lekj1t$v7n$1@ger.gmane.org>
 <CACT3xuXWBQC2s2XxE=Cav+RK78voPjbLA0cWSxL50ekktJZ2cg@mail.gmail.com>
Message-ID: <CACT3xuXu9m8JY6XVdoJwu+cVKkyYwuBs4iUTF_hVoVks-BQt2A@mail.gmail.com>

>
>
>
> Thanks  Peter  and Simon for the hints  it worked  : )  without ' ='
>
> # Python corrupt.py -o INODE -p /ifs/1.txt -q SET -f 1
>
> Current Default Choice :
>
> Choice: INODE
> Choice: SET
> Choice: 1
>
>
>
>

Iam done with the command line parsing but got stuck while trying to
implement switch kind of behavior with dictionaries.  So posting 2 more
questions



Question 1 :


Iam using the options.name  directly  for manipulations is this fine or do
I need to assign it to variable and then use it


Example:


Entered at cli #python corrupt.py -object_type INODE  --path_name/ifs/1.txt
-operation_type SET



Initialize all the command line option and then use it


object_type = options.object_type

path_name  = options.path_name

if object_type == 'LIN':

        corrupt_inode()

   elif  object_type  == 'DATA':

                corrupt_data()



               OR

if options.object_type == 'LIN':

       corrupt_inode()

   elif  options.object_type  == 'DATA':

         corrupt_data()

   elif  options.object_type  == 'INODE':

         corrupt_data()



#output

#python corrupt.py -object_type INODE  -p /ifs/1.txt -q SET -f 10

 -m 10  -n 123  -l  -c

Corrupted inode

_________________________________________________________________________________________________________


Question 2 :


I wanted to use dictionary to match the above if else behavior (we don't
have switch in python I guess ) and  If else looks very untidy.


Is it possible to store the options.object_type as a key in the dictionary
and   then based on the value entered in the command line invoke the
appropriate function



I tried creating a dictionary like this but Iam getting a wrong output




object_type_dictonary = { 'LIN' : corrupt_inode(),

                                      'INODE' : corrupt_lin(),

                                         'DATA' : corrupt_data(),

                   };


and then  ran # python corrupt.py -object_type= inode  (  This prints all
the values for me)


Example :

Corrupted inode

Corrupted LIN

Corrupted  data



PS : If user enters object_type= inode it should execute  corrupt_inode
  and print corrupted inode


Any help on  tips highly helpful :)
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From marko at pacujo.net  Sat Mar  1 06:28:09 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 01 Mar 2014 13:28:09 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
Message-ID: <87k3ceqhti.fsf@elektro.pacujo.net>

Ben Finney <ben+python at benfinney.id.au>:

> Use ?==?, since that's all that matters for getting a value that will
> work fine.

You are telling me to use '==' if I choose string objects and 'is' if I
choose some other objects.

I prefer a solution that works regardless of what objects I choose for
identifiers.

There really is no taboo against string object identity if you know what
you are doing.


Marko


From __peter__ at web.de  Sat Mar  1 06:37:16 2014
From: __peter__ at web.de (Peter Otten)
Date: Sat, 01 Mar 2014 12:37:16 +0100
Subject: Python : parsing the command line options using optparse
References: <CACT3xuWuV8omgE6oV0PNGfwdf-yrO3KPbjHtu=B+NHNuOhA_Jw@mail.gmail.com>
 <leig4s$ri5$1@ger.gmane.org>
 <CACT3xuUGtsER0B3xwAB2CqQ5Zb=v72w8+DQkaYz681xeSeJ2CQ@mail.gmail.com>
 <lekj1t$v7n$1@ger.gmane.org>
 <CACT3xuXWBQC2s2XxE=Cav+RK78voPjbLA0cWSxL50ekktJZ2cg@mail.gmail.com>
 <CACT3xuXu9m8JY6XVdoJwu+cVKkyYwuBs4iUTF_hVoVks-BQt2A@mail.gmail.com>
Message-ID: <lesgo6$m9e$1@ger.gmane.org>

Ganesh Pal wrote:

> Iam using the options.name  directly  for manipulations is this fine or do
> I need to assign it to variable and then use it

> if options.object_type == 'LIN':
>        corrupt_inode()

This is fine. You would only consider storing the value if you are going to 
use it very often (millions rather than thousands) in a time-critical loop.


> I wanted to use dictionary to match the above if else behavior (we don't
> have switch in python I guess ) and  If else looks very untidy.

> Is it possible to store the options.object_type as a key in the dictionary
> and   then based on the value entered in the command line invoke the
> appropriate function

> I tried creating a dictionary like this but Iam getting a wrong output

> object_type_dictonary = { 'LIN' : corrupt_inode(),
>                           'INODE' : corrupt_lin(),
>                           'DATA' : corrupt_data(),
>                    };

> and then  ran # python corrupt.py -object_type= inode  (  This prints all
> the values for me)

That's because you are storing the result of the function call when you 
should be storing the function itself:

# build the dispatch table:
object_type_dictionary = {
    "LIN": corrupt_lin, # no () here, we're storing the function
    "INODE": corrupt_inode,
    "DATA": corrupt_data
}

...

handler = object_type_dictionary[options.object_type] # look up the function
handler() # call it

The last two lines could also be merged into one

object_type_dictionary[options.object_type]()

but the first version may be clearer.



From steve+comp.lang.python at pearwood.info  Sat Mar  1 06:47:03 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 01 Mar 2014 11:47:03 GMT
Subject: Python : parsing the command line options using optparse
References: <CACT3xuWuV8omgE6oV0PNGfwdf-yrO3KPbjHtu=B+NHNuOhA_Jw@mail.gmail.com>
 <leig4s$ri5$1@ger.gmane.org>
 <CACT3xuUGtsER0B3xwAB2CqQ5Zb=v72w8+DQkaYz681xeSeJ2CQ@mail.gmail.com>
 <lekj1t$v7n$1@ger.gmane.org>
 <CACT3xuXWBQC2s2XxE=Cav+RK78voPjbLA0cWSxL50ekktJZ2cg@mail.gmail.com>
 <mailman.7507.1393672393.18130.python-list@python.org>
Message-ID: <5311c8b7$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Sat, 01 Mar 2014 16:43:11 +0530, Ganesh Pal wrote:

> Iam done with the command line parsing but got stuck while trying to
> implement switch kind of behavior with dictionaries.  So posting 2 more
> questions

You should start new threads for new questions. The subject line here has 
nothing to do with the questions you ask.

> Question 1 :
> 
> Iam using the options.name  directly  for manipulations is this fine or
> do I need to assign it to variable and then use it

It is perfectly fine to use options.name directly. There's no need to 
save it to a temporary variable just to use it, unless doing this makes 
your code easier to read.


> Question 2 :
> 
> I wanted to use dictionary to match the above if else behavior (we don't
> have switch in python I guess ) and  If else looks very untidy.
> 
> Is it possible to store the options.object_type as a key in the
> dictionary and   then based on the value entered in the command line
> invoke the appropriate function

Yes. You almost got it right here:

> object_type_dictonary = { 'LIN' : corrupt_inode(),
>                           'INODE' : corrupt_lin(),
>                           'DATA' : corrupt_data(),
>                         };

(By the way, this is Python, not C, and there is no need for redundant 
semi-colons at the end of each line.)

The mistake you made is that you *called* the functions inside the dict. 
Instead, just refer to the function object itself, without calling it:

object_type_dictonary = {
    # no parens after the functions
    'LIN' : corrupt_inode,
    'INODE' : corrupt_lin,
    'DATA' : corrupt_data,
    }


Then, after you look up the object type, then and only then call the 
function:

func = object_type_dictionary[object_type]
func()



-- 
Steven


From rosuav at gmail.com  Sat Mar  1 06:59:52 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 1 Mar 2014 22:59:52 +1100
Subject: Can global variable be passed into Python function?
In-Reply-To: <87k3ceqhti.fsf@elektro.pacujo.net>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmrya+VAB_wMNo7NCa2pFHFubsUkcRHOzMAQSAymObwHxg@mail.gmail.com>

On Sat, Mar 1, 2014 at 10:28 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Ben Finney <ben+python at benfinney.id.au>:
>
>> Use ?==?, since that's all that matters for getting a value that will
>> work fine.
>
> You are telling me to use '==' if I choose string objects and 'is' if I
> choose some other objects.
>
> I prefer a solution that works regardless of what objects I choose for
> identifiers.
>
> There really is no taboo against string object identity if you know what
> you are doing.

And, as proven here in this thread, you do not know what you are doing.

ChrisA


From ganesh1pal at gmail.com  Sat Mar  1 07:12:03 2014
From: ganesh1pal at gmail.com (Ganesh Pal)
Date: Sat, 1 Mar 2014 17:42:03 +0530
Subject: Python : parsing the command line options using optparse
In-Reply-To: <lesgo6$m9e$1@ger.gmane.org>
References: <CACT3xuWuV8omgE6oV0PNGfwdf-yrO3KPbjHtu=B+NHNuOhA_Jw@mail.gmail.com>
 <leig4s$ri5$1@ger.gmane.org>
 <CACT3xuUGtsER0B3xwAB2CqQ5Zb=v72w8+DQkaYz681xeSeJ2CQ@mail.gmail.com>
 <lekj1t$v7n$1@ger.gmane.org>
 <CACT3xuXWBQC2s2XxE=Cav+RK78voPjbLA0cWSxL50ekktJZ2cg@mail.gmail.com>
 <CACT3xuXu9m8JY6XVdoJwu+cVKkyYwuBs4iUTF_hVoVks-BQt2A@mail.gmail.com>
 <lesgo6$m9e$1@ger.gmane.org>
Message-ID: <CACT3xuUpxjGamCx12pDL484EAPr6KM_qr61gCB8uYEP1E2vZxw@mail.gmail.com>

>
> handler = object_type_dictionary[options.object_type] # look up the
> function
> handler() # call it
>
> The last two lines could also be merged into one
>
> object_type_dictionary[options.object_type]()
>
> but the first version may be clearer.
>
>

Thanks  for your valuable inputs all worked :)
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From ganesh1pal at gmail.com  Sat Mar  1 07:17:09 2014
From: ganesh1pal at gmail.com (Ganesh Pal)
Date: Sat, 1 Mar 2014 17:47:09 +0530
Subject: Python : parsing the command line options using optparse
In-Reply-To: <5311c8b7$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <CACT3xuWuV8omgE6oV0PNGfwdf-yrO3KPbjHtu=B+NHNuOhA_Jw@mail.gmail.com>
 <leig4s$ri5$1@ger.gmane.org>
 <CACT3xuUGtsER0B3xwAB2CqQ5Zb=v72w8+DQkaYz681xeSeJ2CQ@mail.gmail.com>
 <lekj1t$v7n$1@ger.gmane.org>
 <CACT3xuXWBQC2s2XxE=Cav+RK78voPjbLA0cWSxL50ekktJZ2cg@mail.gmail.com>
 <mailman.7507.1393672393.18130.python-list@python.org>
 <5311c8b7$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CACT3xuWezjDNN8AWur0aqg3ooSerxO8HBTa1kO7tsnUqx_+FfQ@mail.gmail.com>

On Sat, Mar 1, 2014 at 5:17 PM, Steven D'Aprano <
steve+comp.lang.python at pearwood.info> wrote:

>
> You should start new threads for new questions. The subject line here has
> nothing to do with the questions you ask.
>
>

Sure Steven  and thanks for replying  and  your suggestion for Question 2
 ( same as  Peter Otten ) worked and Iam closing this thread now  :)
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From ben+python at benfinney.id.au  Sat Mar  1 08:03:32 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sun, 02 Mar 2014 00:03:32 +1100
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
Message-ID: <85lhwukr4r.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Ben Finney <ben+python at benfinney.id.au>:
>
> > Use ?==?, since that's all that matters for getting a value that will
> > work fine.
>
> You are telling me to use '==' if I choose string objects and 'is' if I
> choose some other objects.

No. I'm telling you that ?is? is *wrong* for comparing strings, because
it is unreliable.

> I prefer a solution that works regardless of what objects I choose for
> identifiers.

Some languages have a ?symbol? type, whose values can be directly
compared. Python doesn't have such a type. If you want to use strings as
a substitute, go ahead: they work fine.

But compare strings by *equality*, not identity, because it's their
*values* which will be the identifiers. Their object identity will not
be reliably comparable.

That's what everyone has been telling you all along, for reasons already
explained.

> There really is no taboo against string object identity if you know what
> you are doing.

You, as has been amply demonstrated, do not, despite your dogmatic
assertions.

-- 
 \     ?Under democracy one party always devotes its chief energies to |
  `\       trying to prove that the other party is unfit to rule ? and |
_o__)         both commonly succeed, and are right.? ?Henry L. Mencken |
Ben Finney



From stefan_ml at behnel.de  Sat Mar  1 09:26:09 2014
From: stefan_ml at behnel.de (Stefan Behnel)
Date: Sat, 01 Mar 2014 15:26:09 +0100
Subject: insert html into ElementTree without parsing it
In-Reply-To: <b7c05dd5-d25f-428e-b1d5-2ab75ab451f8@googlegroups.com>
References: <b7c05dd5-d25f-428e-b1d5-2ab75ab451f8@googlegroups.com>
Message-ID: <lesqlk$pli$1@ger.gmane.org>

graeme.pietersz at gmail.com, 24.02.2014 10:45:
> I am building HTML pages using ElementTree.
> I need to insert chunks of untrusted HTML into the page. I do not need or want to parse this, just insert it at a particular point as is.

How would you want to find out if it can be safely inserted or not without
parsing it?


> The best solutions I can think of are rather ugly ones: manipulating the string created by tostring.
> 
> Is there a nicer way of doing this? Is it possible, for example, to customise how an element is converted to a string representation? I am open to using something else (e.g. lxml) if necessary.

lxml has a tool to discard potentially unsafe content from HTML files:

http://lxml.de/lxmlhtml.html#cleaning-up-html

Stefan




From breamoreboy at yahoo.co.uk  Sat Mar  1 09:54:43 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 01 Mar 2014 14:54:43 +0000
Subject: Tuples and immutability
In-Reply-To: <dc08f190-e4d3-40bc-9fd3-9fa24f757816@googlegroups.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <dc08f190-e4d3-40bc-9fd3-9fa24f757816@googlegroups.com>
Message-ID: <lessaq$akv$1@ger.gmane.org>

On 01/03/2014 06:16, Mark H. Harris wrote:
> On Friday, February 28, 2014 11:16:18 PM UTC-6, Ian wrote:
>
>> How would you propose doing that?  Bear in mind that while Python
>> knows that tuples specifically are immutable, it doesn't generally
>> know whether a type is immutable.
>
>
> hi Ian,   consider the problem... its a "cake" and "eat it too" scenario...   you can't have your cake and eat it too....
>
> This is what I mean...   the error message is telling the user that it cannot do what he has requested, and yet IT DID.  You have one of two scenarios:   1) the message is arbitrarily lying and it really can assign an immutable's item...  (and it did!)  or 2)  It really should NOT assign an immutables item (the message is truth) but the action was "allowed" anyway despite the protocol and accepted policy...  in which case the two scenarios add up to a giant logical inconsistency...  QED   a bug.
>
> There really is no way to get around this from the average user's perspective. And therefore, this is going to come up again and again and again... because coders don't like unexpected logical inconsistencies.
>
> It is not helpful either to explain it away by knowing how the policy works under the covers... the average user of the python language should not have to understand the policy of the underlying substructure...
>
> 1) either they can't assign the list item of an immutable tuple type (and the action is a flaw, say bug
>
> of
>
> 2) they really CAN set the immutable's list item type (which it did!) and the message is bogus.
>
>
> Its one way or the other....  we can't have our cake and eat it too... this is (one way or the other) a bug.
>
> IMHO
>

would you please be kind enough to use plain English...  your use of 
sentences like this...  is starting to annoy me...

you're also using google groups...  it doesn't wrap paragraphs 
correctly...  please read and action this 
https://wiki.python.org/moin/GoogleGroupsPython...  it does wrap 
paragraphs correctly...  it also prevents us seeing double line spacing...

do you get my drift???

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From thrinaxodon at troll.thrinaxodon  Sat Mar  1 09:50:08 2014
From: thrinaxodon at troll.thrinaxodon (THRINAXODON)
Date: Sat, 01 Mar 2014 09:50:08 -0500
Subject: HUMANS HAVE ORIGINS IN THE DEVONIAN.....
Message-ID: <less2r$tj$3@speranza.aioe.org>

================================
 >BREAKING FUCKING NEWS, ASSHOLES!
================================
 >
THRINAXODON JUST FOUND THREE HUMAN FOSSILS FROM DEVONIAN STRATA IN 
GREENLAND; THE FOSSILS WERE A HUMAN FEMUR, KNEECAP, AND SKULLCAP.
 >
THE SMITHSONIAN IS CHASTISING OVER THESE FINDS, DOING EVERYTHING IN 
THEIR POWER TO CENSOR THE TRUTH.
 >
DONATE TO THE BIOLORD9 FOUNDATION TO FIND OUT HOW TO STOP THE 
SMITHSONIAN FROM CENSORING THE TRUTH, AND LET THE TRUTH THAT HUMAN 
EVOLUTION IS A SCAM BE REVEALED!
 >
===========================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/6f501c469c7af24f#

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/3aad75c16afb0b82#

====================================

http://thrinaxodon.wordpress.com/

===================================

THRINAXODON ONLY HAD THIS TO SAY:

"I..I...I...Can't believe it. This completely disproved Darwinian
orthodoxy."

===================================

THE BASTARDS AT THE SMITHSONIAN, AND THE LEAKEY FOUNDATION ARE ERODING
WITH FEAR.

===========================
THESE ASSHOLES ARE GOING TO DIE:
THOMAS AQUINAS;
ALDOUS HUXLEY;
BOB CASANVOVA;
SkyEyes;
DAVID IAIN GRIEG;
MARK ISAAK;
JOHN HARSHAM;
RICHARD NORMAN;
DR. DOOLITTLE;
CHARLES DARWIN;
MARK HORTON;
ERIK SIMPSON;
HYPATIAB7;
PAUL J. GANS;
JILLERY;
WIKI TRIK;
THRINAXODON;
PETER NYIKOS;
RON OKIMOTO;
JOHN S. WILKINS
===========================

THRINAXODON WAS SCOURING ANOTHER DEVONIAN FOSSIL BED, AND FOUND A
HUMAN SKULL, AND A HUMAN FEMUR. HE ANALYSED THE FINDS, AND SAW THAT
THEY WERE NOT NORMAL ROCKS. THESE WERE FOSSILIZED BONES. THEY EVEN HAD
TOOTH MARKS ON THEM. SO, THRINAXODON BROUGHT THEM TO THE LEAKEY
FOUNDATION, THEY UTTERLY DISMISSED IT, AND SAID, "We want to keep
people thinking that humans evolved 2 Ma." THRINAXODON BROUGHT HIS
SWORD, AND SAID, "SCIENCE CORRECTS ITSELF." RICHARD LEAKEY SAID, "That
is a myth, for people to believe in science." THRINAXODON PLANS TO
BRING DOOM TO SCIENCE, ITSELF.

============================

THRINAXODON IS NOW ON REDDIT
-- 
---Thrinaxodon


From breamoreboy at yahoo.co.uk  Sat Mar  1 10:15:13 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 01 Mar 2014 15:15:13 +0000
Subject: Can global variable be passed into Python function?
In-Reply-To: <CAPTjJmrya+VAB_wMNo7NCa2pFHFubsUkcRHOzMAQSAymObwHxg@mail.gmail.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <CAPTjJmrya+VAB_wMNo7NCa2pFHFubsUkcRHOzMAQSAymObwHxg@mail.gmail.com>
Message-ID: <lestgr$ho4$1@ger.gmane.org>

On 01/03/2014 11:59, Chris Angelico wrote:
> On Sat, Mar 1, 2014 at 10:28 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>
>> There really is no taboo against string object identity if you know what
>> you are doing.
>
> And, as proven here in this thread, you do not know what you are doing.
>

Why do you think I admitted him onto my dream team some days ago? :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From torriem at gmail.com  Sat Mar  1 12:05:37 2014
From: torriem at gmail.com (Michael Torrie)
Date: Sat, 01 Mar 2014 10:05:37 -0700
Subject: Can global variable be passed into Python function?
In-Reply-To: <87k3ceqhti.fsf@elektro.pacujo.net>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
Message-ID: <53121361.8000505@gmail.com>

On 03/01/2014 04:28 AM, Marko Rauhamaa wrote:
> Ben Finney <ben+python at benfinney.id.au>:
> 
>> Use ?==?, since that's all that matters for getting a value that will
>> work fine.
> 
> You are telling me to use '==' if I choose string objects and 'is' if I
> choose some other objects.

No, '==' works fine no matter what objects you assign to your state
variables.

class Foo(object):
    STATE1 = object()
    STATE2 = "testing"
    STATE3 = 2

    def __init__(self):
        self.state = Foo.STATE1

    def bar(self):
        if self.state == Foo.STATE1:
            pass
        elif self.state == Foo.STATE2:
            pass
        elif self.state == Foo.STATE3:
            pass

> I prefer a solution that works regardless of what objects I choose for
> identifiers.

As shown, '==' does work for this too.  I don't know which is more
correct, but it does work.



From steve+comp.lang.python at pearwood.info  Sat Mar  1 12:07:16 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 01 Mar 2014 17:07:16 GMT
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7509.1393675202.18130.python-list@python.org>
Message-ID: <531213c4$0$29987$c3e8da3$5496439d@news.astraweb.com>

On Sat, 01 Mar 2014 22:59:52 +1100, Chris Angelico wrote:

> On Sat, Mar 1, 2014 at 10:28 PM, Marko Rauhamaa <marko at pacujo.net>
> wrote:
>> Ben Finney <ben+python at benfinney.id.au>:
>>
>>> Use ?==?, since that's all that matters for getting a value that will
>>> work fine.
>>
>> You are telling me to use '==' if I choose string objects and 'is' if I
>> choose some other objects.
>>
>> I prefer a solution that works regardless of what objects I choose for
>> identifiers.
>>
>> There really is no taboo against string object identity if you know
>> what you are doing.
> 
> And, as proven here in this thread, you do not know what you are doing.

Steady on, that's a bit harsh. In context, I think that Marko is assuming 
that the caller will only ever use the state values via their symbolic 
names, e.g. only refer to them as IDLE, CONNECTED etc. and never use 
their internal string values "IDLE", "CONNECTED".

I don't think that's a safe assumption, since it requires the caller to 
only ever do the right thing, but if it is true, then using "is" in the 
way he suggests cannot fail.

Still, I've repeatedly asked Marko to justify why we should care about 
the symbols being singletons, and unless I've missed something, he hasn't 
even attempted to justify that. It seems to me that he's just assuming 
that symbols ought to be singletons, hence his focus on identity rather 
than equality.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Sat Mar  1 12:18:22 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 01 Mar 2014 17:18:22 GMT
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
Message-ID: <5312165e$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Sat, 01 Mar 2014 12:31:39 +0200, Marko Rauhamaa wrote:

> I need *identifiers*. I could simply define:
> 
>    class ABC:
>        A = object()
>        B = object()
>        C = object()
> 
> The program would work perfectly.
> 
> Except, if it's got a bug. I know self.abc contains either A, B or C,
> but which one? Printing out self.abc won't give me any help. I could
> print out ABC.A, ABC.B and ABC.C and see which one matches, but that's
> cumbersome.

All very good so far.

 
> The next variant is to use objects that have names:
> 
>    class Symbol:
>        def __init__(self, name):
>            self.name = name
>        def __str__(self):
>            return self.name
> 
>    class ABC:
>        A = Symbol("A")
>        B = Symbol("B")
>        C = Symbol("C")
> 
> 
> The same program still works (and still uses "is" for identity tests,
> mind you).

But why are you using identity tests? Equality will work perfectly well, 
and won't expose the implementation detail that these objects may be 
singletons. That's especially important at the next step, when you 
replace the Symbol class with regular strings. If the caller happens to 
use "C" rather than ABC.C, why is this a problem?



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From marko at pacujo.net  Sat Mar  1 12:23:57 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 01 Mar 2014 19:23:57 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
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 <87k3ceeq0m.fsf@elektro.pacujo.net>
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 <87zjlad8q4.fsf@elektro.pacujo.net>
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Message-ID: <87r46l96j6.fsf@elektro.pacujo.net>

Ben Finney <ben+python at benfinney.id.au>:

> No. I'm telling you that ?is? is *wrong* for comparing strings,
> because it is unreliable.

No, it isn't as long as the string object references have a common
assignment "pedigree." Assignment (including parameter passing) is
guaranteed to preserve identity of any object.


Marko


From rosuav at gmail.com  Sat Mar  1 12:27:28 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 04:27:28 +1100
Subject: Can global variable be passed into Python function?
In-Reply-To: <531213c4$0$29987$c3e8da3$5496439d@news.astraweb.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
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 <874n3irz04.fsf@elektro.pacujo.net>
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 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7509.1393675202.18130.python-list@python.org>
 <531213c4$0$29987$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqfjB6JOsHyjn0ipGTvyhj4LDeF48SWr4=ONFsAhunAiA@mail.gmail.com>

On Sun, Mar 2, 2014 at 4:07 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Sat, 01 Mar 2014 22:59:52 +1100, Chris Angelico wrote:
>> And, as proven here in this thread, you do not know what you are doing.
>
> Steady on, that's a bit harsh. In context, I think that Marko is assuming
> that the caller will only ever use the state values via their symbolic
> names, e.g. only refer to them as IDLE, CONNECTED etc. and never use
> their internal string values "IDLE", "CONNECTED".

A bit harsh, perhaps, but I stand by it: by repeatedly declaring that
something is safe when it has been proven not safe, he shows that he
does not know what he is doing - that he is not fully comprehending
the significance of object value vs identity as regards strings.

Incidentally, Python somewhat creates this issue, by sometimes
interning and sometimes not. (And the same with small integers,
although I've never heard the expression "int interning".) If strings
were always interned, then it would be obvious that identity and value
were one and the same. On the flip side, if a string literal always
created a new string (that is, if it were more like a "string
construction syntax" like square brackets for lists), then it would be
obvious that each one is a separate object. I don't say either option
is worth doing (especially the latter, O!), but by sometimes merging
and sometimes not, Python does slightly blur the line between identity
and value. (Obviously if strings were mutable, they'd *have* to have
separate identities.)

> I don't think that's a safe assumption, since it requires the caller to
> only ever do the right thing, but if it is true, then using "is" in the
> way he suggests cannot fail.

If you're depending on the caller doing the right thing, it's still
safe to use == rather than is. The only reason to use 'is' is to
prevent the caller from stuffing in some other string that happens to
be correct - hence his point about being able to change the keywords.
If the caller stuffs in the string "INIT" instead of the object
Foo.INIT, then "==" will happen to work until such time as Foo.INIT
becomes "INITIALIZING", at which point it breaks. Preventing that
means that unique object identity is crucial to the system working,
and that's pretty much impossible with strings. (I don't say it's
absolutely impossible; maybe if you intern some other string with the
same value, and then construct the string you want out of pieces, and
somehow prevent the compiler from figuring out what you're doing and
optimizing it all away, then maybe you could have something that
doesn't get reused anywhere else. But it's certainly not normal to be
able to be sure of that.)

ChrisA


From marko at pacujo.net  Sat Mar  1 12:29:41 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 01 Mar 2014 19:29:41 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
Message-ID: <87mwh9969m.fsf@elektro.pacujo.net>

Michael Torrie <torriem at gmail.com>:

> No, '==' works fine no matter what objects you assign to your state
> variables.

Well, it doesn't since

   >>> a = float("nan")
   >>> a is a
   True
   >>> a == a
   False

More generally, it depends on how the __eq__ method has been implemented
for the class. You might even (foolishly) define a class such that:

   >>> a == b
   False
   >>> a != b
   False

The "is" operator is immune to such modality.


Marko


From rosuav at gmail.com  Sat Mar  1 12:30:41 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 04:30:41 +1100
Subject: Can global variable be passed into Python function?
In-Reply-To: <87r46l96j6.fsf@elektro.pacujo.net>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7512.1393679028.18130.python-list@python.org>
 <87r46l96j6.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmrL7HyU4--4D8+8UJmQvbYsZmZhVucH0ZJ5HAWojChrZw@mail.gmail.com>

On Sun, Mar 2, 2014 at 4:23 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Ben Finney <ben+python at benfinney.id.au>:
>
>> No. I'm telling you that ?is? is *wrong* for comparing strings,
>> because it is unreliable.
>
> No, it isn't as long as the string object references have a common
> assignment "pedigree." Assignment (including parameter passing) is
> guaranteed to preserve identity of any object.

Of course it is, but your identity tests also depend on there NOT
being a common object when there is NOT an "assignment pedigree". The
positive is guaranteed; the negative is not. And if you don't care
about a false positive - that is, that some other string with the same
value matches - then what you actually want is equality, not identity,
comparison.

ChrisA


From rosuav at gmail.com  Sat Mar  1 12:36:29 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 04:36:29 +1100
Subject: Can global variable be passed into Python function?
In-Reply-To: <87mwh9969m.fsf@elektro.pacujo.net>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpDsSYmB+AHfji7-qPHUK5uy2UQSJ5NkbOAALFPOuXsqQ@mail.gmail.com>

On Sun, Mar 2, 2014 at 4:29 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> You might even (foolishly) define a class such that:
>
>    >>> a == b
>    False
>    >>> a != b
>    False

Not necessarily even foolish; the SQL NULL value [1] behaves like that.

ChrisA

[1] Which isn't a value, except when it is


From rvernucio at gmail.com  Sat Mar  1 12:49:49 2014
From: rvernucio at gmail.com (Renato)
Date: Sat, 1 Mar 2014 09:49:49 -0800 (PST)
Subject: Password validation security issue
Message-ID: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>

Hello everybody, I implemented a password validation with a Python 2.7.5 script in OpenSUSE 13.1. The user calls it passing 'login' and 'password' as arguments. I made a dictionary in the format hashtable = {'login':'password'} and I use this hash table to compare the 'login' and 'password' that were passed in order to validate them. The problem is that any user who can execute the script will be able to read it too (since it must be read by python's interpreter), and this is causing some security issues since any user can access all other users' passwords if he opens this script and reads the code.

My question is: is there a way of preventing the user from reading the script's content? Is there any strategy I could use to hide the passwords from the users?


From ned at nedbatchelder.com  Sat Mar  1 12:56:24 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Sat, 01 Mar 2014 12:56:24 -0500
Subject: Tuples and immutability
In-Reply-To: <2c38b941-9f3f-485f-9e97-525f28c5453a@googlegroups.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <lerd1m$311j$1@cabale.usenet-fr.net>
 <2ddad91d-e188-4fd0-be1c-ed30edbf280b@googlegroups.com>
 <mailman.7501.1393652140.18130.python-list@python.org>
 <2c38b941-9f3f-485f-9e97-525f28c5453a@googlegroups.com>
Message-ID: <let6vq$qc1$1@ger.gmane.org>

On 3/1/14 12:50 AM, Mark H. Harris wrote:
> On Friday, February 28, 2014 11:34:56 PM UTC-6, Ian wrote:
>
>> One very common example of tuples containing lists is when lists are
>> passed to any function that accepts *args, because the extra arguments
>> are passed in a tuple.  A similarly common example is when returning
>> multiple objects from a function, and one of them happens to be a
>> list, because again they are returned in a tuple.
>
>>      def f(*args):
>>          print(args)
>>          return (args[1:]
>>
>>      >>> result = f(1, 2, 3, [4, 5])
>>      (1, 2, 3, [4, 5])
>>      >>> print(result)
>>      (2, 3, [4, 5])
>
> I agree Ian... good points all.   ... again, I'm not arguing with anyone... just saying that an error (whatever we mean by that) should not half-way-fail....   we are only pointing out the problem... we have not idea what the solution is yet.
>
> Intuitively everyone can see that there is a problem here...  the debate cannot be answered either because of the inherent design of python (almost all of which we love). So, as they say, what is a mother to do?  ... I mean, some people's kids...
>
> I don't know how I propose to handle the problem... I think the first step is getting everyone to agree that there IS a problem... then debate how to tackle the solution proposals.
>
> marcus
>

Everyone can agree that it is not great to raise an exception and also 
leave the list modified.  But I very much doubt that anything will be 
done to change the situation.  All of the solutions are too extreme, and 
bring their own infelicities, and the actual problems caused by this 
scenario are vanishingly small.

BTW: I also am mystified why you uses ellipses to end your sentences, 
surely one period would be enough? :)

-- 
Ned Batchelder, http://nedbatchelder.com



From susanaldridge555 at gmail.com  Sat Mar  1 13:03:25 2014
From: susanaldridge555 at gmail.com (Susan Aldridge)
Date: Sat, 1 Mar 2014 10:03:25 -0800 (PST)
Subject: Help with "Guess the number" script
In-Reply-To: <mailman.7516.1393691734.18130.python-list@python.org>
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <mailman.7516.1393691734.18130.python-list@python.org>
Message-ID: <233865a4-cd75-4466-811b-d3cb644c279c@googlegroups.com>

Try this

def guess1(upLimit = 100):
    import random
    num = random.randint(1,upLimit)
    count = 0
    gotIt = False
    while (not gotIt):
        print('Guess a number between 1 and', upLimit, ':')
        guess= int(input())
        count += 1
        if guess == num:
              print('Congrats! You win')
              gotIt = True
        elif guess < num:
              print('Go up!')
        else:
              print('Guess less')
    print('You got it in ', count, 'guesses.')

guess1(100)


From torriem at gmail.com  Sat Mar  1 13:06:54 2014
From: torriem at gmail.com (Michael Torrie)
Date: Sat, 01 Mar 2014 11:06:54 -0700
Subject: Can global variable be passed into Python function?
In-Reply-To: <87mwh9969m.fsf@elektro.pacujo.net>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
Message-ID: <531221BE.1000504@gmail.com>

On 03/01/2014 10:29 AM, Marko Rauhamaa wrote:
> Michael Torrie <torriem at gmail.com>:
> 
>> No, '==' works fine no matter what objects you assign to your state
>> variables.
> 
> Well, it doesn't since
> 
>    >>> a = float("nan")
>    >>> a is a
>    True
>    >>> a == a
>    False
> 
> More generally, it depends on how the __eq__ method has been implemented
> for the class. You might even (foolishly) define a class such that:
> 
>    >>> a == b
>    False
>    >>> a != b
>    False

Yes, good point.



From rosuav at gmail.com  Sat Mar  1 13:11:59 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 05:11:59 +1100
Subject: Password validation security issue
In-Reply-To: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
Message-ID: <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>

On Sun, Mar 2, 2014 at 4:49 AM, Renato <rvernucio at gmail.com> wrote:
> Hello everybody, I implemented a password validation with a Python 2.7.5 script in OpenSUSE 13.1. The user calls it passing 'login' and 'password' as arguments. I made a dictionary in the format hashtable = {'login':'password'} and I use this hash table to compare the 'login' and 'password' that were passed in order to validate them. The problem is that any user who can execute the script will be able to read it too (since it must be read by python's interpreter), and this is causing some security issues since any user can access all other users' passwords if he opens this script and reads the code.
>
> My question is: is there a way of preventing the user from reading the script's content? Is there any strategy I could use to hide the passwords from the users?
>

Yeah, that's a pretty major issue, right there :)

The most common way to deal with this is to salt and hash your
passwords. While that might sound like a great thing to do to
potatoes, it's also the best way to stop your passwords from being
sniffed.

Best practice is to combine the password with the user name and with
some fixed text (the "salt"), and then run it through a
cryptographically secure hashing algorithm. In Python 2.7, you have
the hashlib module:

>>> import hashlib
>>> login = 'rosuav'
>>> password = 'xkcd936passwordgoeshere'
>>> encrypted = hashlib.sha256(login+'NaCl protects your passwords'+password).hexdigest()
>>> encrypted
'b329f2674af4d8d873e264d23713ace4505c211410eb46779c27e02d5a50466c'

Then all you store is that encrypted password. When the user enters
the login and password, you do the same operation, and compare it with
the stored hash; if they're the same, you accept the credentials.

The reason for including two pieces of salt (a constant and the user's
login) is that it ensures that duplicate passwords don't have
identical hashes, and that your set of password hashes are unique to
you (so someone can't have a "standard set of password hashes"). So
put some other string in between the two (or somewhere else in the
string - it doesn't matter how you put the pieces together, as long as
you're consistent).

Also, as hinted in the example above, encourage everyone to use XKCD
936 compliant passwords.

http://xkcd.com/936/

This is not a joke, this is not trivial. Using this scheme, you make
passwords that are orders of magnitude stronger than the classic
"minimum 8 characters, must include uppercase, lowercase, digit,
symbol". If that gives a theoretical 80 character corpus, then it's
insisting on a theoretical 50 bits of entropy (but, as the XKCD above
shows, it's more likely to be roughly half that); you can get pretty
much the same by using four common words at an estimated 11 bits per
word, which assumes you use a pool of just two thousand words. If your
pool's larger (if you use one or two less common words), you could be
looking at a corpus of 65536 words (my /usr/share/dict/words has more
than that), which would give you 64 bits of entropy from four words.
Bank style passwords are *weak*. Long passwords are strong.

So with truly strong passwords, and a hashing system that means an
attacker has to brute-force every possible password to figure out how
to get in, you can be confident that it's safe. But don't be naive;
still do your best to protect the password hashes from scrying eyes -
on Unix, you may be able to use a setuid binary to bounce into your
script, which could then be owned by and readable only by some other
user. Or, depending on how permissions are set up, you could arrange
it so any user may run 'sudo /usr/local/bin/yourscript.py', which
would then be freely able to read from a root-owned file of passwords.
But at this point, we're outside of Python code and into Unix
security, which is quite a different topic.

ChrisA


From marko at pacujo.net  Sat Mar  1 13:25:51 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 01 Mar 2014 20:25:51 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7509.1393675202.18130.python-list@python.org>
 <531213c4$0$29987$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87iorx93o0.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> It seems to me that he's just assuming that symbols ought to be
> singletons, hence his focus on identity rather than equality.

Yes.

A practical angle is this: if I used strings as symbols and compared
them with "==", logically I shouldn't define them as constants but
simply use strings everywhere:

   class Connection:
       def __init__(self):
           self.state = "IDLE"

       def connect(self, address):
           if self.state == "IDLE":
               ...
           elif self.state == ...

The principal (practical) problem with that is that I might make a typo
and write:

           if self.state == "IDLE ":

which could result in some hard-to-find problems. That's why I want get
the help of the Python compiler and always refer to the states through
symbolic constants:

           if self.state == self.IDLE:


Marko


From christian at python.org  Sat Mar  1 13:31:10 2014
From: christian at python.org (Christian Heimes)
Date: Sat, 01 Mar 2014 19:31:10 +0100
Subject: Password validation security issue
In-Reply-To: <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
Message-ID: <let920$fmn$1@ger.gmane.org>

On 01.03.2014 19:11, Chris Angelico wrote:
> On Sun, Mar 2, 2014 at 4:49 AM, Renato <rvernucio at gmail.com> wrote:
>> Hello everybody, I implemented a password validation with a Python 2.7.5 script in OpenSUSE 13.1. The user calls it passing 'login' and 'password' as arguments. I made a dictionary in the format hashtable = {'login':'password'} and I use this hash table to compare the 'login' and 'password' that were passed in order to validate them. The problem is that any user who can execute the script will be able to read it too (since it must be read by python's interpreter), and this is causing some security issues since any user can access all other users' passwords if he opens this script and reads the code.
>>
>> My question is: is there a way of preventing the user from reading the script's content? Is there any strategy I could use to hide the passwords from the users?
>>
> 
> Yeah, that's a pretty major issue, right there :)
> 
> The most common way to deal with this is to salt and hash your
> passwords. While that might sound like a great thing to do to
> potatoes, it's also the best way to stop your passwords from being
> sniffed.
> 
> Best practice is to combine the password with the user name and with
> some fixed text (the "salt"), and then run it through a
> cryptographically secure hashing algorithm. In Python 2.7, you have
> the hashlib module:
> 
>>>> import hashlib
>>>> login = 'rosuav'
>>>> password = 'xkcd936passwordgoeshere'
>>>> encrypted = hashlib.sha256(login+'NaCl protects your passwords'+password).hexdigest()
>>>> encrypted
> 'b329f2674af4d8d873e264d23713ace4505c211410eb46779c27e02d5a50466c'

Please don't do that. It's insecure and not the proper way to handle
passwords. In fact it's insecure on so many levels that I don't know
where to start...

A hash function and a fixed salt are always the wrong way to handle
passwords. You must use a non-deterministic key stretching and key
derivation function with a salt from a CPRNG. For example PBKDF2
(usually used with HMAC as PRF), bcrypt or scrypt are well studied and
tune-able KDFs. You must also use a constant timing comparison function.

You don't have to do all the hard stuff on your own. I highly recommend
`passlib` to handle your passwords. It has a good API and is secure.

Christian






From python.list at tim.thechases.com  Sat Mar  1 13:38:25 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Sat, 1 Mar 2014 12:38:25 -0600
Subject: Password validation security issue
In-Reply-To: <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
Message-ID: <20140301123825.2c2dd24e@bigbox.christie.dr>

On 2014-03-02 05:11, Chris Angelico wrote:
> On Sun, Mar 2, 2014 at 4:49 AM, Renato <rvernucio at gmail.com> wrote:
> > My question is: is there a way of preventing the user from
> > reading the script's content?

Not really.  It might be a bit obfuscated, but 

>> Is there any strategy I could use to hide the passwords from the
>> users?

use Chris's suggestion about hashing.

That said, if the user has access to the source code, there's nothing
preventing them from changing

  if hash(provided_password) == existing_hash:
    do_magic()

into just

  if True:
    do_magic()

and re-running the program.

-tkc




From rosuav at gmail.com  Sat Mar  1 13:43:33 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 05:43:33 +1100
Subject: Password validation security issue
In-Reply-To: <20140301123825.2c2dd24e@bigbox.christie.dr>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <20140301123825.2c2dd24e@bigbox.christie.dr>
Message-ID: <CAPTjJmqWBiu94fPrRbTStqkhN9VJaqVu7kDRdiLWiiSwk1J-FA@mail.gmail.com>

On Sun, Mar 2, 2014 at 5:38 AM, Tim Chase <python.list at tim.thechases.com> wrote:
> That said, if the user has access to the source code, there's nothing
> preventing them from changing
>
>   if hash(provided_password) == existing_hash:
>     do_magic()
>
> into just
>
>   if True:
>     do_magic()
>
> and re-running the program.

They don't necessarily have to have the ability to edit the file.
Based on the original description, the problem is that if Python
running as that user can read the file (to run it), then so can
anything else running as that user. Python doesn't need to be able to
change the file.

ChrisA


From rosuav at gmail.com  Sat Mar  1 13:45:08 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 05:45:08 +1100
Subject: Password validation security issue
In-Reply-To: <let920$fmn$1@ger.gmane.org>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
Message-ID: <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>

On Sun, Mar 2, 2014 at 5:31 AM, Christian Heimes <christian at python.org> wrote:
>>>>> encrypted = hashlib.sha256(login+'NaCl protects your passwords'+password).hexdigest()
>>>>> encrypted
>> 'b329f2674af4d8d873e264d23713ace4505c211410eb46779c27e02d5a50466c'
>
> Please don't do that. It's insecure and not the proper way to handle
> passwords. In fact it's insecure on so many levels that I don't know
> where to start...

Please do start. This is an extremely common practice; are you able,
from just the information above, to figure out the password using
anything better than brute force?

ChrisA


From oscar.j.benjamin at gmail.com  Sat Mar  1 13:55:53 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Sat, 1 Mar 2014 18:55:53 +0000
Subject: Tuples and immutability
In-Reply-To: <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
Message-ID: <CAHVvXxSqBUn+wouwupB9A+Tbd6GvY7ryXVu_KAqAX6sEMqYFrw@mail.gmail.com>

On 27 February 2014 21:47, Nick Timkovich <prometheus235 at gmail.com> wrote:
> On Thu, Feb 27, 2014 at 10:33 AM, Chris Angelico <rosuav at gmail.com> wrote:
>>
>> It's unintuitive, but it's a consequence of the way += is defined. If
>> you don't want assignment, don't use assignment :)
>
> Where is `.__iadd__()` called outside of `list += X`?

Numpy uses it for in-place operations with numpy arrays:

>>> import numpy
>>> a = numpy.arange(10)
>>> a
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> a[::2] += 10
>>> a
array([10,  1, 12,  3, 14,  5, 16,  7, 18,  9])

It makes sense for any mutable type that supports +. The stdlib
doesn't have many of these. The obvious one is list but there's also
MutableString (in 2.x):

>>> from UserString import MutableString
>>> a = MutableString("qwe")
>>> a
'qwe'
>>> b = a
>>> b += "asd"
>>> a
'qweasd'

> If the only difference from `.extend()` is that it returns `self`, but the list was
> already modified anyway, why bother with reassignment?

I don't know of any situation where __iadd__ is defined but doesn't
return self and I can't think of a use case apart from operator abuse.

I had thought that the other difference was that .extend would accept
any iterable but it seems += does also. Perhaps that was changed at
some point.

>>> l = [1, 2, 3]
>>> l + (1, 2, 3)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can only concatenate list (not "tuple") to list
>>> l += (1, 2, 3)
>>> l
[1, 2, 3, 1, 2, 3]


Oscar


From geniusrko at gmail.com  Sat Mar  1 14:12:32 2014
From: geniusrko at gmail.com (geniusrko at gmail.com)
Date: Sat, 1 Mar 2014 11:12:32 -0800 (PST)
Subject: Boxes of O's
Message-ID: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>

Hi 
Can anyone help with this problem 

Create a big box out of n rows of little o's for any desired size n. Use an input statement to allow the user to enter the value for n and then print the properly sized box.

E.g. n = 3						
oooooo
o    o
oooooo

E.g. n = 8
oooooooooooooooo
o              o
o              o
o              o
o              o
o              o
o              o
oooooooooooooooo


using only loops
Thanks


From rosuav at gmail.com  Sat Mar  1 14:16:37 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 06:16:37 +1100
Subject: Boxes of O's
In-Reply-To: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>
References: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>
Message-ID: <CAPTjJmqkAOQugTKS+40JtC-_h6qKhrcc7xQaH2wK5-jSkDc8cQ@mail.gmail.com>

On Sun, Mar 2, 2014 at 6:12 AM,  <geniusrko at gmail.com> wrote:
> Create a big box out of n rows of little o's for any desired size n. Use an input statement to allow the user to enter the value for n and then print the properly sized box.

How far have you gotten so far with your homework? Show us some code
and we can help you debug it.

ChrisA


From geniusrko at gmail.com  Sat Mar  1 14:28:37 2014
From: geniusrko at gmail.com (geniusrko at gmail.com)
Date: Sat, 1 Mar 2014 11:28:37 -0800 (PST)
Subject: Boxes of O's
In-Reply-To: <mailman.7529.1393701408.18130.python-list@python.org>
References: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>
 <mailman.7529.1393701408.18130.python-list@python.org>
Message-ID: <31bde8f6-25a6-484f-af6b-bbef7f7a0fdf@googlegroups.com>

Well, This is what i got 

n = int(input("enter number of o: "))

for i in range(n):
    print("O", end = '')
    for j in range(n* 2):
        print("O", end = '')
    
    print()


From python at mrabarnett.plus.com  Sat Mar  1 14:41:30 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Sat, 01 Mar 2014 19:41:30 +0000
Subject: Boxes of O's
In-Reply-To: <31bde8f6-25a6-484f-af6b-bbef7f7a0fdf@googlegroups.com>
References: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>
 <mailman.7529.1393701408.18130.python-list@python.org>
 <31bde8f6-25a6-484f-af6b-bbef7f7a0fdf@googlegroups.com>
Message-ID: <531237EA.6050704@mrabarnett.plus.com>

On 2014-03-01 19:28, geniusrko at gmail.com wrote:
> Well, This is what i got
>
> n = int(input("enter number of o: "))
>
> for i in range(n):
>      print("O", end = '')
>      for j in range(n* 2):
>          print("O", end = '')
>
>      print()
>
 From the examples:

   The first row has n*2 of 'o'
   There are n-2 middle rows, each with 'o', then n*2-2 spaces, then 'o'
   The last row has n*2 of 'o'

Incidentally, in your code you're writing 'O', not 'o'.



From ian.g.kelly at gmail.com  Sat Mar  1 14:45:55 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 1 Mar 2014 12:45:55 -0700
Subject: Tuples and immutability
In-Reply-To: <9ee137b0-3313-41c6-9792-9438ff05038a@googlegroups.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <9ee137b0-3313-41c6-9792-9438ff05038a@googlegroups.com>
Message-ID: <CALwzidm5ifENtBqBxPEFvg4+rL1zMn_0xoiEuPCvZOCfVZigMg@mail.gmail.com>

On Fri, Feb 28, 2014 at 11:25 PM, Mark H. Harris <harrismh777 at gmail.com> wrote:
> On Friday, February 28, 2014 11:16:18 PM UTC-6, Ian wrote:
>
>> How would you propose doing that?  Bear in mind that while Python
>> knows that tuples specifically are immutable, it doesn't generally
>> know whether a type is immutable.
>
> I was going to bed, and then thought of the solution.  Allow the action.
>
> Hold the error pending until the action either succeeds or fails for the "item," in this case a list, and then post the error for the tuple depending... this would make the whole mess consistent, and even compatible with the idea of dynamic name and type binding...
>
> So, in other words, the action should be permitted, and actually was allowed, and the message is incorrectly reporting something that for this particular "item" is NOT true. The error message (and timing of same) is the bug  (philosophically).
>
> Under the covers it may be (and probably is) more complicated.

Indeed.  For one thing, __iadd__ is not required to return the object
it was called on; it could return some other object.  Imagine a
balanced binary tree that is stored by referencing the root node
object (whether this is good design is tangential; it's a possible
design).  If the __iadd__ operator is implemented to insert a node,
and it causes the root node to change, then it might return that new
root node, expecting it to be assigned.  If Python simply ignores the
exception from the assignment, then the data structure has been
modified in-place, but the tuple does not contain the correct object,
and worst of all no exception has been raised to alert anybody of this
failure condition.  So at best you could only ignore these exceptions
when the object returned by __iadd__ is self, which to be fair is
probably most of the time.

Additionally, recall my statement up-thread that "If you skip the
assignment, and that assignment is meaningful to whatever the left
side may be (e.g. assigning to a descriptor or something that invokes
__setitem__ or __setattr__), then the operation is not equivalent."
If you quash the exception from the assignment because the __iadd__
call succeeded, then you have effectively skipped the assignment and
then lied to the programmer about it.  For example, imagine a list
subclass that contains other lists but only permits itself to be
nested 1-deep; the contained lists are required to be flat.  The
__setitem__ method for the class might enforce the constraint and
perhaps also update a count of the total combined length of the nested
lists.  Then suppose we have this code:

    lol = ListOfLists([1,2,3], [4], [6, 7, 8, 9])
    lol[1] += [5, [5.25, 5.5, 5.75]]

The effect of this is that the middle sublist has been extended to
include a doubly-nested list.  __setitem__ was then called, which
noticed that the list it was passed includes another nested list, so
it raised an exception instead of performing the assignment and
updating the count.  The ListOfLists is now in an invalid state, but
if Python swallows the exception raised by __setitem__, then there is
nothing to warn the programmer of this (until something else
mysteriously fails to process the ListOfLists later on).  The result
is code that is hard to debug.

Now, we might notice that the above code would probably not raise a
TypeError, which is the exception we would expect if trying to mutate
an immutable object, so we might revise the rule again: we only
silence the exception if __iadd__ returns self and the exception is a
TypeError.  But even then, we have no guarantee that this is what the
TypeError was meant to convey.  A TypeError may have simply propagated
up from other buggy code that was indirectly called by __setitem__, a
legitimate error that should be brought to the programmer's attention.

tldr: Swallowing exceptions is a risky practice unless you're quite
sure that you know where the exception is coming from and that it's
safe to ignore, and the language runtime should practically never do
this.


From rosuav at gmail.com  Sat Mar  1 14:54:23 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 06:54:23 +1100
Subject: Boxes of O's
In-Reply-To: <31bde8f6-25a6-484f-af6b-bbef7f7a0fdf@googlegroups.com>
References: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>
 <mailman.7529.1393701408.18130.python-list@python.org>
 <31bde8f6-25a6-484f-af6b-bbef7f7a0fdf@googlegroups.com>
Message-ID: <CAPTjJmrpKHnaNVfZDJnJhRpZoDSuwrhi=3dDSHGRrXMn82jVjA@mail.gmail.com>

On Sun, Mar 2, 2014 at 6:28 AM,  <geniusrko at gmail.com> wrote:
> Well, This is what i got
>
> n = int(input("enter number of o: "))
>
> for i in range(n):
>     print("O", end = '')
>     for j in range(n* 2):
>         print("O", end = '')
>
>     print()

Okay! Good. Now, presumably this isn't working yet, or you wouldn't be
asking. So we just need the other crucial part of the puzzle: What is
it doing wrong? That might be an exception (copy and paste it all,
including the full traceback), or it might be producing the wrong
output, or maybe it produces the right output on everything except
some specific input.

I'll level with you here. We do not want to do your homework for you,
and we do not want anyone else to do your homework. When you're asked
to write code like this, it's not because the teacher/tutor wants the
code written - it's because you need to learn what you're doing.
Having someone else hand you perfectly working code defeats that
purpose, and it will tend to produce a sort of faux comprehension that
results in you getting a certificate and a job, while being still
quite incompetent as a programmer. Now, you may protest that it's not
as bad as that (and you'd probably be right - you have produced some
partially-working code there), but that's the extreme, and going even
part-way down that path is a Bad Thing. We, as programmers, would hate
to be coworkers to someone who glided through some course by getting
someone else to do the work; we do not want to have to try to work
with that sort of person.

(Digression: I have, and quite a few of us here probably have, worked
with exactly such a person. In my case, eventually even the boss/owner
figured out that he was a rubbish programmer; when we eventually dug
into his code thoroughly, we threw out the whole lot and literally
started over with a blank file. But before that, we found gems like
this PHP code - by the way, it *is* possible to write good PHP code,
even though the language is itself pretty appalling, but this... isn't
proof of that.

$step = 1;
do
{
    switch ($step) {
        case 1:
            .... code code code ....
            break;
        case 2:
            .... code code code ....
            break;
        default:
            ... raise an error ....
    }
} while (++$step<2);

This code was supposed to verify certain requirements on an incoming
HTTP request. What you may not notice - and I didn't notice when I saw
this and decided to simplify the code - is that this is NOT the
for-switch paradigm, it's something even worse: a for-switch with an
off-by-one, so the only code actually executed is the "case 1" block.
And since we had properly working code in our client, none of the
errors that the "case 2" block was supposed to catch ever actually got
triggered, so we didn't see a problem... until I cleaned up the code,
and discovered that "case 2" had bugs in it. This is what happens when
you have incompetent people writing code. This is why we are strongly
disinclined to give you the answers. End digression.)

However, while we won't just give you the answers, we *will* gladly
help you to understand what's going on. So if you post code and output
(maybe an error) and ask a specific question, preferably one that
shows some level of comprehension, we will cheerfully put in quite a
bit of time to help you understand the error message, or learn how to
decipher Python tracebacks, or whatever. Helping you to understand
things makes you a better programmer, and by extension improves the
world's total programming skill; giving you the answers makes you no
better and possibly worse (by encouraging laziness), and so we don't
want to do it.

So, there you have it. Don't be a bad programmer. :) You'll find more
handy tips here - it's an invaluable resource:

http://www.catb.org/~esr/faqs/smart-questions.html

ChrisA


From christian at python.org  Sat Mar  1 14:54:24 2014
From: christian at python.org (Christian Heimes)
Date: Sat, 01 Mar 2014 20:54:24 +0100
Subject: Password validation security issue
In-Reply-To: <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
Message-ID: <letdt5$1g3$1@ger.gmane.org>

On 01.03.2014 19:45, Chris Angelico wrote:
> On Sun, Mar 2, 2014 at 5:31 AM, Christian Heimes <christian at python.org> wrote:
>>>>>> encrypted = hashlib.sha256(login+'NaCl protects your passwords'+password).hexdigest()
>>>>>> encrypted
>>> 'b329f2674af4d8d873e264d23713ace4505c211410eb46779c27e02d5a50466c'
>>
>> Please don't do that. It's insecure and not the proper way to handle
>> passwords. In fact it's insecure on so many levels that I don't know
>> where to start...
> 
> Please do start. This is an extremely common practice; are you able,
> from just the information above, to figure out the password using
> anything better than brute force?

I'm aware that it's still a common technique. It makes me sad everytime
I see code that uses SHA256 for password hashing. :( Why haven't people
learnt from mistakes like LinkedIn's and Adobe's password disaster?

Yes, for most applications brute force is still the best option to crack
the password. Passwords are usually rather short, have a low entropy and
modern hardware is insanely fast. With software like [1] and a fast GPU
it is possible to do more than 10*10^9 checks/second for SHA-256.

Clever and very capable people have come up with algorithms like [2] to
make it much harder to crack passwords. The Wikipedia articles on KDF
and KSA explain both algorithm much better than I could. The PHC [3] is
a recent attempt to come up with an even more secure algorithm.

Please don't implement PBKDF2 on your own. Django, several other Python
libraries and OpenSSL did and made a really bad error that lead to a DoS
vulnerability.

Christian

[1] http://hashcat.net/oclhashcat/
[2] http://en.wikipedia.org/wiki/Key_derivation_function
[3] https://password-hashing.net/



From shiblydu60 at yahoo.com  Sat Mar  1 13:10:58 2014
From: shiblydu60 at yahoo.com (Golam Md. Shibly)
Date: Sat, 1 Mar 2014 10:10:58 -0800 (PST)
Subject: How to extract contents of inner text of html tag?
Message-ID: <1393697458.5147.YahooMailNeo@web126004.mail.ne1.yahoo.com>

Hi,

###in.txt
<kbd class="command">
    cp -v --remove-destination /usr/share/zoneinfo/
    <em class="replaceable"><code><xxx></code></em>
       \
    /etc/localtime
</kbd>

import sys
import unicodedata
from bs4 import BeautifulSoup

file_name="in.txt"
html_doc=open(file_name,'r')
soup=BeautifulSoup(html_doc)
#print soup.prettify().encode('utf-8')
#file_to_write.writelines( soup.prettify().encode() )

all_kbd=soup.find_all('kbd')

for line in all_kbd:
	if line.string == None:		
		extract_code=line.code.extract().string
		#store_code=line.code.decompose()
		for inside_line in line:
			if "<<" not in inside_line and "EOF" not in inside_line:
				if len(inside_line)>0: 
					print inside_line
					print extract_code

expected output:
    cp -v --remove-destination /usr/share/zoneinfo/<xxx>\      
    /etc/localtime


Got output:
    cp -v --remove-destination /usr/share/zoneinfo/
    
None

       \
    /etc/localtime

None 

shibly
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-list/attachments/20140301/c24d6f53/attachment.html>

From rosuav at gmail.com  Sat Mar  1 15:11:49 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 07:11:49 +1100
Subject: Password validation security issue
In-Reply-To: <letdt5$1g3$1@ger.gmane.org>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
Message-ID: <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>

On Sun, Mar 2, 2014 at 6:54 AM, Christian Heimes <christian at python.org> wrote:
> Yes, for most applications brute force is still the best option to crack
> the password. Passwords are usually rather short, have a low entropy and
> modern hardware is insanely fast. With software like [1] and a fast GPU
> it is possible to do more than 10*10^9 checks/second for SHA-256.

Using XKCD 936's estimate, 44 bits of entropy would still require
17592 seconds of processing at 10^9 per second. That's not a lot if
someone's personally targeting you *and* they know you use XKCD 936
*and* know the exact set of 2048 words that you drew your password
from *and* they know how you lay them out (spaces between, no spaces,
whether or not you capitalize the words, etc etc). Not knowing any of
these would add a few more bits of entropy; and if you use
/usr/share/dict/words and take only those words which consist entirely
of lower-case letters, then your corpus is over 65536 words [1], so
you have 64 bits of entropy. Even at 10^10 checks/second (which is
what 10*10^9 is, but that's an odd way to write it), that would be
21350 *days* of dedicated processing, just to crack the one password.
If cracking my password, and mine alone, in sixty years, is considered
"insanely fast", then I'm going to keep using SHA-256 for a while.

The problem isn't SHA-256. The problem is insecure passwords, the way
we've been taught to make them by the banks. Hence, XKCD 936.

ChrisA

[1] On my Debian Wheezy system:
$ grep -c '^[a-z]*$' /usr/share/dict/words
72861


From harrismh777 at gmail.com  Sat Mar  1 16:01:41 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Sat, 1 Mar 2014 13:01:41 -0800 (PST)
Subject: Tuples and immutability
In-Reply-To: <mailman.7514.1393685683.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <dc08f190-e4d3-40bc-9fd3-9fa24f757816@googlegroups.com>
 <mailman.7514.1393685683.18130.python-list@python.org>
Message-ID: <3ad31471-26ea-401d-a860-3604cf0e55b7@googlegroups.com>

On Saturday, March 1, 2014 8:54:43 AM UTC-6, Mark Lawrence wrote:

> you're also using google groups...  it doesn't wrap paragraphs 
> 
> correctly...  please read and action this 
> 
> https://wiki.python.org/moin/GoogleGroupsPython...  it does wrap 
> 
> paragraphs correctly...  it also prevents us seeing double line spacing...
> 
> 
> 
> do you get my drift???
> 

hi Mark,  yes, I understand. I am using google groups (for the moment) and it does not wrap correctly, at least not on my end.  It also adds additional carrots > that make replying difficult.

The elipses thing is a bad habit which I 'picked up' in academia lately.  We use elipses frequently in papers (also this---which also annoys people) and there is no problem.  In a writing context the elipses seem to function for some people (intentionally) as 'um'.  When humans speak they use the word 'um' to pause between though context and its usually unintentional at the surface.  Often when I write the elipses  (...)  show up for the same reason.  I really don't know that I'm doing it... it just happens. So, I am working on it.  No, you're not the first to mention it. Its one of my many flaws.

Thanks for keeping me accountable.

Enjoy the day!

marcus


From breamoreboy at yahoo.co.uk  Sat Mar  1 16:20:10 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 01 Mar 2014 21:20:10 +0000
Subject: Can tuples be replaced with lists all the time?
In-Reply-To: <roy-099864.12485223022014@news.panix.com>
References: <64af70e3-6876-4fbf-8386-330d2f48735a@googlegroups.com>
 <led9s7$req$1@reader1.panix.com> <roy-099864.12485223022014@news.panix.com>
Message-ID: <letiu0$hfj$1@ger.gmane.org>

On 23/02/2014 17:48, Roy Smith wrote:
> In article <led9s7$req$1 at reader1.panix.com>,
>   Grant Edwards <invalid at invalid.invalid> wrote:
>
>> In constrast, tuples are often used as fixed-length heterogenous
>> containers (more like a struct in C except the fields are named 0, 1,
>> 2, 3, etc.).  In a particular context, the Nth element of a tuple will
>> always mean one thing (e.g. a person's last name) while the Mth
>> element will always be something else (e.g. a person's age).
>
> And, of course, namedtuples make that much more explicit.
>
> It also appears that tuples are more memory efficient.  I just ran some
> quick tests on my OSX box.  Creating a list of 10 million [1, 2, 3, 4,
> 5] lists gave me a 1445 MB process.   The name number of (1, 2, 3, 4, 5)
> tuples was 748 MB.  I'm sure this is implementation dependent, but it
> seems plausible to assume similar results will be had on other
> implementations.
>

In CPython a list is overallocated so there's usually spare slots 
available if you want to add something to it.  In contrast you know when 
you create the tuple just how big it is so no overallocation is needed.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From harrismh777 at gmail.com  Sat Mar  1 16:21:44 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Sat, 1 Mar 2014 13:21:44 -0800 (PST)
Subject: Tuples and immutability
In-Reply-To: <mailman.7499.1393651028.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
Message-ID: <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>

On Friday, February 28, 2014 11:16:18 PM UTC-6, Ian wrote:

> How would you propose doing that?  Bear in mind that while Python
> knows that tuples specifically are immutable, it doesn't generally
> know whether a type is immutable.  

hi Ian,  I thought of something else after I slept on it, so to speak. Consider this:

>>> s=(2,3,[42,43,44],7)
>>> s[2]
[42, 43, 44]
>>> 

s[2] is a list. We should be able to change s[2] even though its within a tuple, like the:

[42, 43, 44]
>>> s[2].append(45)
>>> s[2]
[42, 43, 44, 45]       <===== no error
>>> 

or like this:

>>> s[2]
[42, 43, 44, 45]
>>> s[2]=s[2]+[46]
Traceback (most recent call last):
  File "<pyshell#8>", line 1, in <module>
    s[2]=s[2]+[46]                    <==========error,  but look below======
TypeError: 'tuple' object does not support item assignment
>>> 
>>> s[2]
[42, 43, 44, 45]        <=========also no change to list  !!
>>> 

The point I'm trying to make with this post is that  s[2]+=[46]   and  s[2]=s[2]+[46]  are handled inconsistently.  In each case (whether the list is part of a tuple or not)  s[2]  is a valid list and should be mutable.   In every case, in fact, it is.  In each case, in fact, the change might occur.  But, the change occurs in the first case (append) without an error.  The change occurs in the next case too (+=) but with an error not related to the tuple.  The change does not occur in the third case (s=s+ with an error) but the list is not changed ! 

We all know this is not good. We also all know that its because of implementation details the user/coder should not need to know.  QED:  a bug.

Having slept on it, I am remembering my Zen of Python:  Errors should never pass silently, unless explicitly silenced.  It looks to me like  (+=)  in this case is not being handled correctly under the covers.  At any rate the three scenarios of trying to change a mutable list as an immutable tuple item should be handled consistently.  Either we can change the tuple item (if its a list) or we can't.  Also, if we cannot then the expected error should be consistent.

Wow. I think I got that whole thing out without one elipses.

Cheers


From roy at panix.com  Sat Mar  1 13:30:06 2014
From: roy at panix.com (Roy Smith)
Date: Sat, 01 Mar 2014 13:30:06 -0500
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
Message-ID: <roy-E94637.13300601032014@news.panix.com>

In article <87mwh9969m.fsf at elektro.pacujo.net>,
 Marko Rauhamaa <marko at pacujo.net> wrote:

> Michael Torrie <torriem at gmail.com>:
> 
> > No, '==' works fine no matter what objects you assign to your state
> > variables.
> 
> Well, it doesn't since
> 
>    >>> a = float("nan")
>    >>> a is a
>    True
>    >>> a == a
>    False
> 
> More generally, it depends on how the __eq__ method has been implemented
> for the class. You might even (foolishly) define a class such that:
> 
>    >>> a == b
>    False
>    >>> a != b
>    False

Well, there's always things like SQL's NULL, which is both not equal and 
not not equal to itself.


From roy at panix.com  Sat Mar  1 15:25:47 2014
From: roy at panix.com (Roy Smith)
Date: Sat, 01 Mar 2014 15:25:47 -0500
Subject: Password validation security issue
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <mailman.7533.1393703687.18130.python-list@python.org>
Message-ID: <roy-9A72E9.15254701032014@news.panix.com>

In article <mailman.7533.1393703687.18130.python-list at python.org>,
 Christian Heimes <christian at python.org> wrote:

>  With software like [1] and a fast GPU
> it is possible to do more than 10*10^9 checks/second for SHA-256.

Just out of curiosity, how does that differ from 10^10 checks/second?


From harrismh777 at gmail.com  Sat Mar  1 16:40:20 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Sat, 1 Mar 2014 13:40:20 -0800 (PST)
Subject: Can global variable be passed into Python function?
In-Reply-To: <mailman.7502.1393655058.18130.python-list@python.org>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <db181305-97fe-4385-bf11-5323d4bd1160@googlegroups.com>
 <87iorzf4ro.fsf@elektro.pacujo.net>
 <mailman.7479.1393613988.18130.python-list@python.org>
 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <0b414429-74ee-45dd-9465-c87e98c362f2@googlegroups.com>
 <mailman.7485.1393634419.18130.python-list@python.org>
 <4bd11eec-395a-4484-a991-9fabf12328e1@googlegroups.com>
 <mailman.7495.1393639309.18130.python-list@python.org>
 <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
 <mailman.7502.1393655058.18130.python-list@python.org>
Message-ID: <cfeaefbf-22d8-478a-8423-2d102a52a2ab@googlegroups.com>

On Saturday, March 1, 2014 12:24:15 AM UTC-6, Chris Angelico wrote:
> much code. If you want to change anything, you potentially have to
> 
> edit three places: the list of constants at the top, the condition
> 
> function, and the switch.
> 
> 
> 
> This can't be your idea of readability. Show me where I'm wrong.
> 
> 
> 
> ChrisA

hi Chris,  I don't think you're wrong.  There are two issues for me (and one of them is not how the switch is implemented).

1) Is it easier for average users of python as a language to read switch case default,  or if elif else ?

2) Would most average users concur that 'readable' means something like, "readily understandable at quick glance, or rapid preview" (or quiv).

I readily admit that 'subjective' is the operative work here. As Guido found at his 2007 keynote most experienced devs are not clamoring for a switch block. Just so. But I'm not thinking of experienced devs. I'm thinking of the average coder who is used to looking at switch blocks.  

I personally can see and understand a switch block 2x to 3x faster than looking at an elif chain. Because I am primarily a C programmer and I personally use and read switch blocks.

An experienced python dev can readily 'see' an elif chain, well, because that's all they have and that's all they look at day to day.  So, naturally a python dev is going to think an elif chain is readable. 

Thank you sir, you have good insights. A quote from the high seas is classy.

(another post with no elipses)

Cheers


From breamoreboy at yahoo.co.uk  Sat Mar  1 17:01:12 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 01 Mar 2014 22:01:12 +0000
Subject: Can global variable be passed into Python function?
In-Reply-To: <cfeaefbf-22d8-478a-8423-2d102a52a2ab@googlegroups.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <db181305-97fe-4385-bf11-5323d4bd1160@googlegroups.com>
 <87iorzf4ro.fsf@elektro.pacujo.net>
 <mailman.7479.1393613988.18130.python-list@python.org>
 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <0b414429-74ee-45dd-9465-c87e98c362f2@googlegroups.com>
 <mailman.7485.1393634419.18130.python-list@python.org>
 <4bd11eec-395a-4484-a991-9fabf12328e1@googlegroups.com>
 <mailman.7495.1393639309.18130.python-list@python.org>
 <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
 <mailman.7502.1393655058.18130.python-list@python.org>
 <cfeaefbf-22d8-478a-8423-2d102a52a2ab@googlegroups.com>
Message-ID: <letlau$dl1$1@ger.gmane.org>

On 01/03/2014 21:40, Mark H. Harris wrote:
> On Saturday, March 1, 2014 12:24:15 AM UTC-6, Chris Angelico wrote:
>> much code. If you want to change anything, you potentially have to
>>
>> edit three places: the list of constants at the top, the condition
>>
>> function, and the switch.
>>
>>
>>
>> This can't be your idea of readability. Show me where I'm wrong.
>>
>>
>>
>> ChrisA
>
> hi Chris,  I don't think you're wrong.  There are two issues for me (and one of them is not how the switch is implemented).
>
> 1) Is it easier for average users of python as a language to read switch case default,  or if elif else ?
>
> 2) Would most average users concur that 'readable' means something like, "readily understandable at quick glance, or rapid preview" (or quiv).
>
> I readily admit that 'subjective' is the operative work here. As Guido found at his 2007 keynote most experienced devs are not clamoring for a switch block. Just so. But I'm not thinking of experienced devs. I'm thinking of the average coder who is used to looking at switch blocks.
>
> I personally can see and understand a switch block 2x to 3x faster than looking at an elif chain. Because I am primarily a C programmer and I personally use and read switch blocks.
>
> An experienced python dev can readily 'see' an elif chain, well, because that's all they have and that's all they look at day to day.  So, naturally a python dev is going to think an elif chain is readable.
>
> Thank you sir, you have good insights. A quote from the high seas is classy.
>
> (another post with no elipses)
>
> Cheers
>

No elipses, just the paragraphs not wrapped and the double line spacing. 
  Good old gg, I just love it.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From gheskett at wdtv.com  Sat Mar  1 16:55:11 2014
From: gheskett at wdtv.com (Gene Heskett)
Date: Sat, 1 Mar 2014 16:55:11 -0500
Subject: posting code snippets
In-Reply-To: <leq6j9$mnb$2@reader1.panix.com>
References: <e77aff42-6ec3-4749-9683-6ebb2a33ac1a@googlegroups.com>
 <mailman.7458.1393566098.18130.python-list@python.org>
 <leq6j9$mnb$2@reader1.panix.com>
Message-ID: <201403011655.11405.gheskett@wdtv.com>

On Saturday 01 March 2014 16:52:44 Grant Edwards did opine:

> On 2014-02-28, Chris Angelico <rosuav at gmail.com> wrote:
> > The problem does have to believe that the rubber duck/teddy
> > bear/figurine is an expert, though. I've had my siblings or parents
> > come to me with problems and, without saying a word or touching the
> > computer or anything, I've solved them. The problem itself respects
> > my skill, and retracts its objection and solves itself.
> 
> The same thing works with expensive/complex test equipment instead of
> an expert.
> 
> You drag out the lab scope, logic analyzer, spectrum analyzer, sweep
> generator, strip plotter, and the machine that goes "ping".  You start
> to get everything set up to nail that problem securely to the
> dissecting board.  Long before you actually get to that point, the
> problem becomes intimidated and reveals itself and a solution.

Chuckle ;-)

Is there not a Murphy's Law corollary on that, Grant?  I have certainly 
been there and done that enough times to know its 100% true.

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

NOTICE: Will pay 100 USD for an HP-4815A defective but
complete probe assembly.



From christian at python.org  Sat Mar  1 17:07:24 2014
From: christian at python.org (Christian Heimes)
Date: Sat, 01 Mar 2014 23:07:24 +0100
Subject: Password validation security issue
In-Reply-To: <roy-9A72E9.15254701032014@news.panix.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <mailman.7533.1393703687.18130.python-list@python.org>
 <roy-9A72E9.15254701032014@news.panix.com>
Message-ID: <letlmg$gne$1@ger.gmane.org>

On 01.03.2014 21:25, Roy Smith wrote:
> In article <mailman.7533.1393703687.18130.python-list at python.org>,
>  Christian Heimes <christian at python.org> wrote:
> 
>>  With software like [1] and a fast GPU
>> it is possible to do more than 10*10^9 checks/second for SHA-256.
> 
> Just out of curiosity, how does that differ from 10^10 checks/second?


I find 10 * 10^9 easier to read because it has more resemblance to "10
billion". Next time I'll use the normalized scientific form 1.0e10. ;)



From harrismh777 at gmail.com  Sat Mar  1 17:07:37 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Sat, 1 Mar 2014 14:07:37 -0800 (PST)
Subject: Can global variable be passed into Python function?
In-Reply-To: <mailman.7537.1393711293.18130.python-list@python.org>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
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 <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
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 <mailman.7537.1393711293.18130.python-list@python.org>
Message-ID: <b50d1c92-deab-481b-bc06-73b32cccd822@googlegroups.com>

On Saturday, March 1, 2014 4:01:12 PM UTC-6, Mark Lawrence wrote:

> 
> No elipses, just the paragraphs not wrapped and the double line spacing. 
> 
>   Good old gg, I just love it.

How do I fix it?   Is there a setting someplace?  I tried pulling up the page you linked, but blank.

Thanks in advance.


From rosuav at gmail.com  Sat Mar  1 17:11:21 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 09:11:21 +1100
Subject: Can global variable be passed into Python function?
In-Reply-To: <cfeaefbf-22d8-478a-8423-2d102a52a2ab@googlegroups.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
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 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
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 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
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Message-ID: <CAPTjJmqLFxLeSkA7Fv3nSyEDncy_TcnUG10_BRLLKruPs0F6dQ@mail.gmail.com>

On Sun, Mar 2, 2014 at 8:40 AM, Mark H. Harris <harrismh777 at gmail.com> wrote:
> hi Chris,  I don't think you're wrong.  There are two issues for me (and one of them is not how the switch is implemented).
>
> 1) Is it easier for average users of python as a language to read switch case default,  or if elif else ?
>
> I personally can see and understand a switch block 2x to 3x faster than looking at an elif chain. Because I am primarily a C programmer and I personally use and read switch blocks.

Sure. But before you can ask us to consider how readable it is, we
need to have comparisons. Mock up a switch statement equivalent and
show us how it'd be better. I just looked at your version, and
couldn't see any way that it would be an improvement, because it
required that there be the exact same if/elif chain to figure out what
to switch on. So give us your readable version, in an exact
reimplementation of the if/elif chain, so we can see exactly how it
would go.

ChrisA


From rosuav at gmail.com  Sat Mar  1 17:13:25 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 09:13:25 +1100
Subject: Password validation security issue
In-Reply-To: <letlmg$gne$1@ger.gmane.org>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
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 <roy-9A72E9.15254701032014@news.panix.com>
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Message-ID: <CAPTjJmo_5MzehVwHxmjLZwD9xXxFpPLfrQYNq74Nkq_6hBin-w@mail.gmail.com>

On Sun, Mar 2, 2014 at 9:07 AM, Christian Heimes <christian at python.org> wrote:
> On 01.03.2014 21:25, Roy Smith wrote:
>> In article <mailman.7533.1393703687.18130.python-list at python.org>,
>>  Christian Heimes <christian at python.org> wrote:
>>
>>>  With software like [1] and a fast GPU
>>> it is possible to do more than 10*10^9 checks/second for SHA-256.
>>
>> Just out of curiosity, how does that differ from 10^10 checks/second?
>
>
> I find 10 * 10^9 easier to read because it has more resemblance to "10
> billion". Next time I'll use the normalized scientific form 1.0e10. ;)

I wasn't sure if it ought to have been 10^9 or 10^10. In any case,
that makes only one order of magnitude of difference, and based on the
way I generate passwords, that still leaves it at 60-ish years of GPU
spinning. (It'd be 600 years at 10^9.)

ChrisA


From rosuav at gmail.com  Sat Mar  1 17:16:35 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 09:16:35 +1100
Subject: posting code snippets
In-Reply-To: <leq6j9$mnb$2@reader1.panix.com>
References: <e77aff42-6ec3-4749-9683-6ebb2a33ac1a@googlegroups.com>
 <85ppm8nqx7.fsf@benfinney.id.au>
 <mailman.7458.1393566098.18130.python-list@python.org>
 <leq6j9$mnb$2@reader1.panix.com>
Message-ID: <CAPTjJmpa+4BNC9Tse=FrpdfknW5Cc3-FwF7AV5P1+hnQCMgK5A@mail.gmail.com>

On Sat, Mar 1, 2014 at 1:31 AM, Grant Edwards <invalid at invalid.invalid> wrote:
> You drag out the lab scope, logic analyzer, spectrum analyzer, sweep
> generator, strip plotter, and the machine that goes "ping".  You start
> to get everything set up to nail that problem securely to the
> dissecting board.  Long before you actually get to that point, the
> problem becomes intimidated and reveals itself and a solution.

*ALL* my machines go ping. It's fundamental to network debugging. I
know that's not what you meant, but somehow it comes to the same
thing. :)

And yep. That is so absolutely right. Problems know when concealment
becomes pointless.

ChrisA


From rosuav at gmail.com  Sat Mar  1 17:29:25 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 09:29:25 +1100
Subject: intersection, union, difference,
 symmetric difference for dictionaries
In-Reply-To: <leivbq$hs0$1@reader1.panix.com>
References: <G57Pu.24239$Th2.4990@tornado.fastwebnet.it>
 <leivbq$hs0$1@reader1.panix.com>
Message-ID: <CAPTjJmq-gNZ=G5co+1+gk1ZuXDLUhe-5WHFX2_Azwnpb-tJZwg@mail.gmail.com>

On Wed, Feb 26, 2014 at 7:44 AM, John Gordon <gordon at panix.com> wrote:
> In <G57Pu.24239$Th2.4990 at tornado.fastwebnet.it> mauro <mauro at gmail.com> writes:
>
>> - Dictionaries and sets are both accessed by key
>
> As far as I have used sets, they are not accessed by key.
>
>>>> x = set([1, 2, 'buckle my shoe'])
>>>> x
> set([1, 2, 'buckle my shoe'])
>>>> 1 in x
> True
>>>> 5 in x
> False

>>> x = {1:3, 2:4, 'buckle my shoe':'spamming the door'}
>>> x
{1: 3, 2: 4, 'buckle my shoe': 'spamming the door'}
>>> 1 in x
True
>>> 5 in x
False

A dict does the exact same thing with its keys as a set does with its
elements. Actually, one of the things that periodically trips me up
when I switch from Pike to Python is that a Python set can't be used
like this:

>>> x = set()
>>> x["test"] = 1
>>> x["foo"] = 1
>>> assert x == {"test","foo"}

Instead, I have to use x.add("test"). In Pike, I can treat a set as if
it were a mapping where every value is simply the integer 1 (Python
could use True instead). Setting it to any truthy value would add it,
setting to any falsy value would remove it. This wouldn't be a huge
change; it certainly wouldn't fundamentally change the set type -
because it *is* working with keys.

Hmm. Actually, it shouldn't be too hard to subclass and add that. Lessee.

class set(set):
    def __setitem__(self, key, state):
        if state: self.add(key)
        else: self.remove(key)
    def __getitem__(self, key):
        return key in self

I might need to toss that into site.py or something. It'd work as long
as I don't use set literal notation anywhere.

ChrisA


From ben+python at benfinney.id.au  Sat Mar  1 17:30:20 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sun, 02 Mar 2014 09:30:20 +1100
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
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 <87k3ceeq0m.fsf@elektro.pacujo.net>
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 <531213c4$0$29987$c3e8da3$5496439d@news.astraweb.com>
 <87iorx93o0.fsf@elektro.pacujo.net>
Message-ID: <85ha7hlfgj.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
>
> > It seems to me that he's just assuming that symbols ought to be
> > singletons, hence his focus on identity rather than equality.
>
> Yes.

Give that up, then. Your assumption is false in Python, and is not
needed to get the behaviour you say you need.

> A practical angle is this: if I used strings as symbols and compared
> them with "==", logically I shouldn't define them as constants but
> simply use strings everywhere

Yes, that works fine. It's also quite understandable for the reader.

> The principal (practical) problem with that is that I might make a
> typo and write:
>
>            if self.state == "IDLE ":
>
> which could result in some hard-to-find problems.

That's just one of a huge variety of problems. Write a comprehensive
unit test suite to catch this and a great many other errors.

> That's why I want get the help of the Python compiler and always refer
> to the states through symbolic constants

Python doesn't let you compare symbols, only values. Work within its
constraints.

-- 
 \     ?I cannot conceive that anybody will require multiplications at |
  `\   the rate of 40,000 or even 4,000 per hour ?? ?F. H. Wales, 1936 |
_o__)                                                                  |
Ben Finney



From harrismh777 at gmail.com  Sat Mar  1 17:32:43 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Sat, 1 Mar 2014 14:32:43 -0800 (PST)
Subject: Mac vs. Linux for Python Development
In-Reply-To: <2465a8c7-ce0e-4606-ad3b-9135c96e3e4c@googlegroups.com>
References: <2465a8c7-ce0e-4606-ad3b-9135c96e3e4c@googlegroups.com>
Message-ID: <4e741358-ce12-40ac-97b8-3bbbf2d6ddca@googlegroups.com>

On Sunday, February 23, 2014 2:43:14 AM UTC-6, twiz wrote:

> I'm sure this is a common question but I can't seem to find a previous thread that addresses it.   If one one exists, please point me to it.

My personal preference for writing and testing python code is Gnu/Linux as a platform (free libre open easier to build from C sources etc). As an editor, VI of course.  Although, I can honestly say I've been using the latest GNU Emacs lately. It has a very nice python mode. I also use TextWrangler from time to time (can be extended with scripts and it has the same 'feel' as the IDLE editor (kind-of).

The main problem you will see with OSX (if you're not careful) is that IDLE will be unstable.  To be fair about it, its not IDLE's problem, per se.  Its about tcl/tk tkinter.  DO NOT use the built-in tcl that comes from Apple, nor the one that comes through the Apple store!  Actually go to the Active TCL site and download the version related to your system (yes there is a different one depending on 10.5 10.6 etc).

Py3.3.4 and the latest Active TCL are stable on OSX 10.6 or higher. I have been very pleased with IDLE on both Gnu/Linux and OSX ( I refuse to use Windows ever again, ever) and my latest experience has been fabulous, really.  My hat is off to the folks that have made IDLE the simple stable and powerful IDE that it is. I am being genuine about this.

Another reason for using Gnu/Linux (and/or OSX) is that generally they are faster.  Faster loading, and faster running.  Serious.  I have been hearing of (4) second import times for decimal, for instance. Its almost instantaneous on Gnu/Linux, or OSX.  Also, run times are considerably faster.  That has less to do with the Windows version of python, and more to do with the Windows version. YMMV

If you want to extend your python code with C (as many of us do) well OSX and/or Gnu/Linux are your best bets there too, and frankly Gnu/Linux is the better of the two (from personal experience). OSX 10.6 uses the GNU gcc compiler by default, but the Apple idiosyncratic approach to builds can be annoying. Although, its minimal really (hardly worth mentioning). If you want to build python from sources (as many of us do) my personal opinion is also that Gnu/Linux is the way to go there too. 

I agree with most of the rest of the posts here that personal preference is at play primarily. Your editor run environment is going to be more important to you than your platform. There is one main difference to that, and it has to do with what you're used to.  In IDLE on Gnu/Linux the menu options are on the top of the IDE.  In OSX they are on the OSX tool bar at top left (where they are for every other OSX app). OSX guys don't mind this, but Gnu/Linux guys hate it (sometimes).  Also, the menu items on Gnu/Linux can be 'torn' off (its a tcl/tk tkinter thing) and on OSX that does not work. Also the 'Options' menu item on OSX has nothing in it. The Options menu is in Preferences in the IDLE drop down on the OSX tool bar.  Other than those things, I have spent many cheerful hours in the OSX IDLE editor and have been happy as a clam.  Same goes for the Gnu/Linux IDLE editor. 

If you want to use terminals on OSX you'll want to install  Quartz  and run the terminal on the emulated X environment.  It works better for python IMHO.  The built-in terminal for OSX need serious configuring (which is possible) because its color is bad, and its tiny by default, with a crummy font. All of that can be changed, but it just works better to use XQuartz.

Enjoy

Cheers



From ben+python at benfinney.id.au  Sat Mar  1 17:34:15 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sun, 02 Mar 2014 09:34:15 +1100
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
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 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7512.1393679028.18130.python-list@python.org>
 <87r46l96j6.fsf@elektro.pacujo.net>
Message-ID: <85d2i5lfa0.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Ben Finney <ben+python at benfinney.id.au>:
>
> > No. I'm telling you that ?is? is *wrong* for comparing strings,
> > because it is unreliable.
>
> No, it isn't as long as the string object references have a common
> assignment "pedigree." Assignment (including parameter passing) is
> guaranteed to preserve identity of any object.

The unreliability isn't ?will the same object have the same identity??.
The unreliability is ?will objects defined elsewhere have a different
identity?? In the case of Python strings, the latter question is not
reliably answerable from the programmer's perspective.

You are obstinately ignoring the point that the identity of a string is
*not* guaranteed to be different from a string with the same value.

Since you're persistently misconstruing what is being said to you, I'm
not going to run through it all again.

-- 
 \     ?[W]e are still the first generation of users, and for all that |
  `\      we may have invented the net, we still don't really get it.? |
_o__)                                                   ?Douglas Adams |
Ben Finney



From ben+python at benfinney.id.au  Sat Mar  1 17:36:07 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sun, 02 Mar 2014 09:36:07 +1100
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
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 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
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 <mailman.7479.1393613988.18130.python-list@python.org>
 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <mailman.7480.1393622633.18130.python-list@python.org>
 <ler0tk$1oo$1@reader1.panix.com>
Message-ID: <858ustlf6w.fsf@benfinney.id.au>

Grant Edwards <invalid at invalid.invalid> writes:

> On 2014-02-28, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>
> > http://c2.com/cgi/wiki?SwitchStatementsSmell
>
> So lack of a switch state is an attempt [?]

Since when is the absence of action an ?attempt? to do anything?

You're assuming the not-doing of something must have a purpose. That
assumption doesn't seem justified.

-- 
 \     ?You are welcome to visit the cemetery where famous Russian and |
  `\    Soviet composers, artists, and writers are buried daily except |
_o__)                   Thursday.? ?Russian orthodox monastery, Moscow |
Ben Finney



From harrismh777 at gmail.com  Sat Mar  1 17:50:45 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Sat, 1 Mar 2014 14:50:45 -0800 (PST)
Subject: Can global variable be passed into Python function?
In-Reply-To: <mailman.7546.1393713606.18130.python-list@python.org>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <db181305-97fe-4385-bf11-5323d4bd1160@googlegroups.com>
 <87iorzf4ro.fsf@elektro.pacujo.net>
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 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <mailman.7480.1393622633.18130.python-list@python.org>
 <ler0tk$1oo$1@reader1.panix.com>
 <mailman.7546.1393713606.18130.python-list@python.org>
Message-ID: <e60c8b48-8e05-4f09-a0ba-00ba4fd36e4e@googlegroups.com>

On Saturday, March 1, 2014 4:36:07 PM UTC-6, Ben Finney wrote:
> Since when is the absence of action an "attempt" to do anything?
> 
> You're assuming the not-doing of something must have a purpose. That
> assumption doesn't seem justified.

Correct.  Argument from silence is logical fallacy;  lack of motion is not the "doing" of being motionless.

:)


From rosuav at gmail.com  Sat Mar  1 17:57:30 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 09:57:30 +1100
Subject: Mac vs. Linux for Python Development
In-Reply-To: <4e741358-ce12-40ac-97b8-3bbbf2d6ddca@googlegroups.com>
References: <2465a8c7-ce0e-4606-ad3b-9135c96e3e4c@googlegroups.com>
 <4e741358-ce12-40ac-97b8-3bbbf2d6ddca@googlegroups.com>
Message-ID: <CAPTjJmrBU9K0aoJyCUmif1FCExtbsuq27pGxiRvyNd=yVn-D5g@mail.gmail.com>

On Sun, Mar 2, 2014 at 9:32 AM, Mark H. Harris <harrismh777 at gmail.com> wrote:
> Py3.3.4 and the latest Active TCL are stable on OSX 10.6 or higher. I have been very pleased with IDLE on both Gnu/Linux and OSX ( I refuse to use Windows ever again, ever) and my latest experience has been fabulous, really.  My hat is off to the folks that have made IDLE the simple stable and powerful IDE that it is. I am being genuine about this.
>
> Another reason for using Gnu/Linux (and/or OSX) is that generally they are faster.  Faster loading, and faster running.  Serious.  I have been hearing of (4) second import times for decimal, for instance. Its almost instantaneous on Gnu/Linux, or OSX.  Also, run times are considerably faster.  That has less to do with the Windows version of python, and more to do with the Windows version. YMMV
>

The point of this thread isn't really about Windows, so I'll try to
keep it brief, but there are a couple of things I should clarify. The
first one is about the 4+ second import time for decimal. I cited
that, recently, and comparing that with "almost instantaneous" on
Debian (which is what I experience) isn't entirely fair, because it's
more about cold cache versus warm cache. (When I shut down IDLE and
fire it up again, I get sub-second import time. Not as fast as the "so
quick as to be immeasurable" that my Debian box gave, but still
quicker than the 4ish second cold cache.)

Actually, I do find that my Linux boxes manage their disk caches far
better than my Windows boxes do. Not sure if that's Linux versus
Windows, or the ext3/4 versus NTFS file system drivers, or something
else, but a warm cache on any of my Linux boxes gives a *huge*
advantage, and my Windows boxes still show it a bit slower.

ChrisA


From nad at acm.org  Sat Mar  1 18:07:29 2014
From: nad at acm.org (Ned Deily)
Date: Sat, 01 Mar 2014 15:07:29 -0800
Subject: Mac vs. Linux for Python Development
References: <2465a8c7-ce0e-4606-ad3b-9135c96e3e4c@googlegroups.com>
 <4e741358-ce12-40ac-97b8-3bbbf2d6ddca@googlegroups.com>
Message-ID: <nad-4137A5.15072901032014@news.gmane.org>

In article <4e741358-ce12-40ac-97b8-3bbbf2d6ddca at googlegroups.com>,
 "Mark H. Harris" <harrismh777 at gmail.com> wrote:
> [...]
> The main problem you will see with OSX (if you're not careful) is that IDLE 
> will be unstable.  To be fair about it, its not IDLE's problem, per se.  Its 
> about tcl/tk tkinter.  DO NOT use the built-in tcl that comes from Apple, nor 
> the one that comes through the Apple store!  Actually go to the Active TCL 
> site and download the version related to your system (yes there is a 
> different one depending on 10.5 10.6 etc).

The gory details are here:
http://www.python.org/download/mac/tcltk/

TL;DR You'll need to install newer versions of Python (like those 
download from python.org) that link with third-party builds of Tcl/Tk 
rather than use the Pythons and Tcl/Tk that Apple ships with OS X 10.6+.

> [...]
> If you want to use terminals on OSX you'll want to install  Quartz  and run 
> the terminal on the emulated X environment.  It works better for python IMHO. 
>  The built-in terminal for OSX need serious configuring (which is possible) 
> because its color is bad, and its tiny by default, with a crummy font. All of 
> that can be changed, but it just works better to use XQuartz.

That certainly is a matter of preference.  There are plenty of drawbacks 
to using X11-based apps on OS X.  I wouldn't advise new users to OS X to 
go that route unless they were really set on using X11 entirely and, in 
that case, why use OS X at all?  If you don't like Apple's built-in 
Terminal.app, another option is to use iTerm 2, an open source native 
alternative that has many more features.  

http://www.iterm2.com/

It's also available through MacPorts.

-- 
 Ned Deily,
 nad at acm.org



From steve+comp.lang.python at pearwood.info  Sat Mar  1 18:13:22 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 01 Mar 2014 23:13:22 GMT
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7509.1393675202.18130.python-list@python.org>
 <531213c4$0$29987$c3e8da3$5496439d@news.astraweb.com>
 <87iorx93o0.fsf@elektro.pacujo.net>
Message-ID: <53126992$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Sat, 01 Mar 2014 20:25:51 +0200, Marko Rauhamaa wrote:

> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
> 
>> It seems to me that he's just assuming that symbols ought to be
>> singletons, hence his focus on identity rather than equality.
> 
> Yes.
> 
> A practical angle is this: if I used strings as symbols and compared
> them with "==", logically I shouldn't define them as constants 

That doesn't follow. There is no logical connection between using named 
constants (well, pseudo-constants, constants by convention only) and ==. 
You can do both, or neither, or either one, whichever suits you.

You might as well say that when you have float constants:

TAU = 6.283185307179586

that "logically" implies that you are prohibited in asking whether 
another float is less than or greater than TAU.

[...]
> The principal (practical) problem with that is that I might make a typo
> and write:
> 
>            if self.state == "IDLE ":

Then used named constants. 

    if self.state == IDLE:


See how easy it is? Just replace "is" with == unless you have a good 
reason for caring about identity instead of equality.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From tjreedy at udel.edu  Sat Mar  1 18:15:10 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sat, 01 Mar 2014 18:15:10 -0500
Subject: Can tuples be replaced with lists all the time?
In-Reply-To: <letiu0$hfj$1@ger.gmane.org>
References: <64af70e3-6876-4fbf-8386-330d2f48735a@googlegroups.com>
 <led9s7$req$1@reader1.panix.com> <roy-099864.12485223022014@news.panix.com>
 <letiu0$hfj$1@ger.gmane.org>
Message-ID: <letplo$opk$1@ger.gmane.org>

On 3/1/2014 4:20 PM, Mark Lawrence wrote:
> On 23/02/2014 17:48, Roy Smith wrote:

>> It also appears that tuples are more memory efficient.  I just ran some
>> quick tests on my OSX box.  Creating a list of 10 million [1, 2, 3, 4,
>> 5] lists gave me a 1445 MB process.   The name number of (1, 2, 3, 4, 5)
>> tuples was 748 MB.  I'm sure this is implementation dependent, but it
>> seems plausible to assume similar results will be had on other
>> implementations.

The numbers sound right.

> In CPython a list is overallocated so there's usually spare slots
> available if you want to add something to it.  In contrast you know when
> you create the tuple just how big it is so no overallocation is needed.

Besides which, in CPython, a tuple is one block of memory, with a 
PyObject header followed by the object references, while a list uses 2 
blocks of memory. The first has a PyObject header, followed by a 
reference to the list block, its allocated length (minimum 8 I believe), 
and its current in-use length. The over-allocated list block, which must 
also start on a 4 or 8 byte alignment boundary, has the object 
references plus extra space.


-- 
Terry Jan Reedy



From breamoreboy at yahoo.co.uk  Sat Mar  1 18:21:57 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 01 Mar 2014 23:21:57 +0000
Subject: Can global variable be passed into Python function?
In-Reply-To: <b50d1c92-deab-481b-bc06-73b32cccd822@googlegroups.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <db181305-97fe-4385-bf11-5323d4bd1160@googlegroups.com>
 <87iorzf4ro.fsf@elektro.pacujo.net>
 <mailman.7479.1393613988.18130.python-list@python.org>
 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <0b414429-74ee-45dd-9465-c87e98c362f2@googlegroups.com>
 <mailman.7485.1393634419.18130.python-list@python.org>
 <4bd11eec-395a-4484-a991-9fabf12328e1@googlegroups.com>
 <mailman.7495.1393639309.18130.python-list@python.org>
 <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
 <mailman.7502.1393655058.18130.python-list@python.org>
 <cfeaefbf-22d8-478a-8423-2d102a52a2ab@googlegroups.com>
 <mailman.7537.1393711293.18130.python-list@python.org>
 <b50d1c92-deab-481b-bc06-73b32cccd822@googlegroups.com>
Message-ID: <letq2a$nht$1@ger.gmane.org>

On 01/03/2014 22:07, Mark H. Harris wrote:
> On Saturday, March 1, 2014 4:01:12 PM UTC-6, Mark Lawrence wrote:
>
>>
>> No elipses, just the paragraphs not wrapped and the double line spacing.
>>
>>    Good old gg, I just love it.
>
> How do I fix it?   Is there a setting someplace?  I tried pulling up the page you linked, but blank.
>
> Thanks in advance.
>

https://wiki.python.org/moin/GoogleGroupsPython

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
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From harrismh777 at gmail.com  Sat Mar  1 19:23:10 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Sat, 1 Mar 2014 16:23:10 -0800 (PST)
Subject: Can global variable be passed into Python function?
In-Reply-To: <mailman.7550.1393716131.18130.python-list@python.org>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <db181305-97fe-4385-bf11-5323d4bd1160@googlegroups.com>
 <87iorzf4ro.fsf@elektro.pacujo.net>
 <mailman.7479.1393613988.18130.python-list@python.org>
 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <0b414429-74ee-45dd-9465-c87e98c362f2@googlegroups.com>
 <mailman.7485.1393634419.18130.python-list@python.org>
 <4bd11eec-395a-4484-a991-9fabf12328e1@googlegroups.com>
 <mailman.7495.1393639309.18130.python-list@python.org>
 <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
 <mailman.7502.1393655058.18130.python-list@python.org>
 <cfeaefbf-22d8-478a-8423-2d102a52a2ab@googlegroups.com>
 <mailman.7537.1393711293.18130.python-list@python.org>
 <b50d1c92-deab-481b-bc06-73b32cccd822@googlegroups.com>
 <mailman.7550.1393716131.18130.python-list@python.org>
Message-ID: <268ea8b1-85a8-4b41-bbe2-b8a13ca0a469@googlegroups.com>

On Saturday, March 1, 2014 5:21:57 PM UTC-6, Mark Lawrence wrote:

> https://wiki.python.org/moin/GoogleGroupsPython

Thanks, Mark.  Whoohoo! Looks like gg has some work to do. rats(). Ok, so I'm typing away here and when
I get to the boarder I should press the enter key so that the text is forced to wrap to the next line so that
you don't see the text as a run-off the page nuisance and complete annoyance leading to homicidal rage
and/or other illicit behaviors like nail-biting. 
How does this look on your news client. I just need to setup an nntp server and use a real client.

Thanks for your input Mark. 

Peace.   marcus 


From rosuav at gmail.com  Sat Mar  1 19:28:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 11:28:43 +1100
Subject: Can global variable be passed into Python function?
In-Reply-To: <268ea8b1-85a8-4b41-bbe2-b8a13ca0a469@googlegroups.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <5310b031$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <db181305-97fe-4385-bf11-5323d4bd1160@googlegroups.com>
 <87iorzf4ro.fsf@elektro.pacujo.net>
 <mailman.7479.1393613988.18130.python-list@python.org>
 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <0b414429-74ee-45dd-9465-c87e98c362f2@googlegroups.com>
 <mailman.7485.1393634419.18130.python-list@python.org>
 <4bd11eec-395a-4484-a991-9fabf12328e1@googlegroups.com>
 <mailman.7495.1393639309.18130.python-list@python.org>
 <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
 <mailman.7502.1393655058.18130.python-list@python.org>
 <cfeaefbf-22d8-478a-8423-2d102a52a2ab@googlegroups.com>
 <mailman.7537.1393711293.18130.python-list@python.org>
 <b50d1c92-deab-481b-bc06-73b32cccd822@googlegroups.com>
 <mailman.7550.1393716131.18130.python-list@python.org>
 <268ea8b1-85a8-4b41-bbe2-b8a13ca0a469@googlegroups.com>
Message-ID: <CAPTjJmqgh5-n8Fgki+VMd8gRzCW5np64kinKa9_B6eWf8Gv_nA@mail.gmail.com>

On Sun, Mar 2, 2014 at 11:23 AM, Mark H. Harris <harrismh777 at gmail.com> wrote:
> On Saturday, March 1, 2014 5:21:57 PM UTC-6, Mark Lawrence wrote:
>
>> https://wiki.python.org/moin/GoogleGroupsPython
>
> Thanks, Mark.  Whoohoo! Looks like gg has some work to do. rats(). Ok, so I'm typing away here and when
> I get to the boarder I should press the enter key so that the text is forced to wrap to the next line so that
> you don't see the text as a run-off the page nuisance and complete annoyance leading to homicidal rage
> and/or other illicit behaviors like nail-biting.
> How does this look on your news client. I just need to setup an nntp server and use a real client.

The usual recommendation is to wrap to 70-80 characters. Most likely
you're seeing a proportionally-spaced font, so going for the border of
the display is going to be inherently sloppy.

What I would recommend, if you don't feel like setting up NNTP, is to
subscribe to the mailing list:

https://mail.python.org/mailman/listinfo/python-list

All the same content, but via email instead. Take your pick between
that and a newsreader - whichever's easier to get to work.

ChrisA


From breamoreboy at yahoo.co.uk  Sat Mar  1 19:36:07 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 02 Mar 2014 00:36:07 +0000
Subject: Can global variable be passed into Python function?
In-Reply-To: <268ea8b1-85a8-4b41-bbe2-b8a13ca0a469@googlegroups.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <db181305-97fe-4385-bf11-5323d4bd1160@googlegroups.com>
 <87iorzf4ro.fsf@elektro.pacujo.net>
 <mailman.7479.1393613988.18130.python-list@python.org>
 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <0b414429-74ee-45dd-9465-c87e98c362f2@googlegroups.com>
 <mailman.7485.1393634419.18130.python-list@python.org>
 <4bd11eec-395a-4484-a991-9fabf12328e1@googlegroups.com>
 <mailman.7495.1393639309.18130.python-list@python.org>
 <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
 <mailman.7502.1393655058.18130.python-list@python.org>
 <cfeaefbf-22d8-478a-8423-2d102a52a2ab@googlegroups.com>
 <mailman.7537.1393711293.18130.python-list@python.org>
 <b50d1c92-deab-481b-bc06-73b32cccd822@googlegroups.com>
 <mailman.7550.1393716131.18130.python-list@python.org>
 <268ea8b1-85a8-4b41-bbe2-b8a13ca0a469@googlegroups.com>
Message-ID: <letudd$u6c$1@ger.gmane.org>

On 02/03/2014 00:23, Mark H. Harris wrote:
> On Saturday, March 1, 2014 5:21:57 PM UTC-6, Mark Lawrence wrote:
>
>> https://wiki.python.org/moin/GoogleGroupsPython
>
> Thanks, Mark.  Whoohoo! Looks like gg has some work to do. rats(). Ok, so I'm typing away here and when
> I get to the boarder I should press the enter key so that the text is forced to wrap to the next line so that
> you don't see the text as a run-off the page nuisance and complete annoyance leading to homicidal rage
> and/or other illicit behaviors like nail-biting.
> How does this look on your news client. I just need to setup an nntp server and use a real client.
>
> Thanks for your input Mark.
>
> Peace.   marcus
>

I love it when a plan comes together :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From harrismh777 at gmail.com  Sat Mar  1 19:49:28 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Sat, 1 Mar 2014 16:49:28 -0800 (PST)
Subject: extend methods of decimal module
In-Reply-To: <vg3wqgewgqc.fsf@coffee.modeemi.fi>
References: <02cdd9c7-aef7-4cc7-a813-cd1c9627ceb4@googlegroups.com>
 <mailman.7160.1392836388.18130.python-list@python.org>
 <94b1962a-0004-4c5b-b484-972a166b88b5@googlegroups.com>
 <CAKJDb-NaZmLysq+2KWgd_f4UPKCk7jdLZkvcCM6ECL5TSAwCRQ@mail.gmail.com>
 <mailman.7165.1392847869.18130.python-list@python.org>
 <55525f2c-fd3a-4927-b642-2dbf5eae7e9b@googlegroups.com>
 <mailman.7432.1393520859.18130.python-list@python.org>
 <vg3wqgewgqc.fsf@coffee.modeemi.fi>
Message-ID: <360ca828-1524-4594-97d5-26363210c5df@googlegroups.com>

On Saturday, March 1, 2014 12:55:07 AM UTC-6, Anssi Saari wrote:
> I recently watched a presentation by Jessica McKellar of PSF about what
> Python needs to stay popular. Other than the obvious bits (difficulties
> of limited support of Python on major platforms like Windows and mobile)
> the slight lack of perfection in IDLE was mentioned. Specifically the
> old blog post titled "The Things I Hate About IDLE That I Wish Someone
> Would Fix" at

> http://inventwithpython.com/blog/2011/11/29/the-things-i-hate-about-idle-that-i-wish-someone-would-fix/

hi Anssi,  this discussion really doesn't belong in this thread, but I'll give you my two cents
on it anyway, just because I put the random comment in here to begin with.

The blog link which you posted is quite old, and yes, as I remember back to the 2009-2011 time
frame IDLE had some problems with stability and some other issues related to tkinter. My experience 
with IDLE today is one of stability usefulness; clean and simple.

Like that FORD commercial here in the States, " Have you driven and IDLE lately?"

Some of the bloggers 'hates' are actually features of IDLE and we really don't want to change them. Some of them have been fixed. Some of them are annoyances not with IDLE per se, but with tcl/tk 
and are a tkinter thing. For instance, the blogger 'hates' the menu tear-off feature. I love it. All of my 
tcl/tk apps have tear-off menus; its totally a tkinter thing and if you're not used to apps written with
the tk library then this 'feature' may annoy you.

The IDLE concept was to have an IDE written in pure python that would use the tk library. If you've not written any code using the tk library then try it. GUI apps can be built with the tk library (with either tcl, or with python, and others) that are reduced to a few lines of code vs. many pages of code. In two pages of tk coding I can create a GUI app that would use 16 pages of code written in C, and 8-16 pages of code written in C++ or Java. The down-side to the tk library is that the GUI work they do for you under
the covers (which is extensive by the way) makes some assumptions and simplifies the options. So, 
you trade off the speed and efficiency of writing the app and getting it to market quickly, with not 
having the explicit control over the GUI that you might have if you had written the code to Q, or GTK,
or some such.

Producing IDLE using tk was genius on the part of Guido initially. The tradition has been kept up, but
has not received the priority that other python issues have received. By the way, there are other  python
IDEs out there (I don't use them, just pointing out that they are available). 

IDLE is free, its efficient, and for the moment its also very stable and highly useful. If you have not
driven an IDLE lately, give it a try. Also, my experience with the devs on IDLE (and particularly Terry Reedy) is that they have been very responsive, helpful, even courteous and professional. So, I think the
blogger was a little too harsh. 

Cheers


From cs at zip.com.au  Sat Mar  1 19:55:51 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Sun, 2 Mar 2014 11:55:51 +1100
Subject: Mac vs. Linux for Python Development
In-Reply-To: <nad-4137A5.15072901032014@news.gmane.org>
References: <nad-4137A5.15072901032014@news.gmane.org>
Message-ID: <20140302005551.GA74610@cskk.homeip.net>

On 01Mar2014 15:07, Ned Deily <nad at acm.org> wrote:
> In article <4e741358-ce12-40ac-97b8-3bbbf2d6ddca at googlegroups.com>,
>  "Mark H. Harris" <harrismh777 at gmail.com> wrote:
> > [...]
> > If you want to use terminals on OSX you'll want to install  Quartz  and run 
> > the terminal on the emulated X environment.  It works better for python IMHO. 
> >  The built-in terminal for OSX need serious configuring (which is possible) 
> > because its color is bad, and its tiny by default, with a crummy font. All of 
> > that can be changed, but it just works better to use XQuartz.
> 
> That certainly is a matter of preference.  There are plenty of drawbacks 
> to using X11-based apps on OS X.  I wouldn't advise new users to OS X to 
> go that route unless they were really set on using X11 entirely and, in 
> that case, why use OS X at all?  If you don't like Apple's built-in 
> Terminal.app, another option is to use iTerm 2, an open source native 
> alternative that has many more features.  
> 
> http://www.iterm2.com/
> 
> It's also available through MacPorts.
> 

I also recommend iTerm2. It is really good, far better than OSX's
Terminal app.

I run it full screen and split it into panes, typically 3 or 4
vertical and then as many horizontal as required (ssh to multiple
hosts); I edit in a full height pane usually.

To reiterate from a post to mutt-users:

I like iTerm2 for the following reasons:

  - focus follows mouse

  - selecting text can be set to set the cut buffer immediately, no %C
    needed. Like X11.

  - horizontal and vertical pane tiling
    I've bound shift-%V to open a new vertical pane (splits the current
    pane vertically) and shift-%T to open a new horizontal pane (splits
    the current pane horizontally).
    This is outstandingly useful for working in multiple shells.
    I do a lot of remote admin and opening shells on a bunch of machines
    nicely arranged for coordinated work is very pleasing.

And of course I've spent some time tuning fonts and colours, and made
things slightly transparent with a slight brightening for the currently
focussed pane. iTerm2 has lots of features, but the ones above are the
real winners for me.

Here's a screenshot of this message:

  https://www.dropbox.com/s/3zvit1cwuoac80h/iterm2-fullscreen-2014-03-02-11.49.02.png

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

TeX: When you pronounce it correctly to your computer, the terminal may
     become slightly moist.     - D. E. Knuth.


From nad at acm.org  Sat Mar  1 19:55:58 2014
From: nad at acm.org (Ned Deily)
Date: Sat, 01 Mar 2014 16:55:58 -0800
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87iorzf4ro.fsf@elektro.pacujo.net>
 <mailman.7479.1393613988.18130.python-list@python.org>
 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <0b414429-74ee-45dd-9465-c87e98c362f2@googlegroups.com>
 <mailman.7485.1393634419.18130.python-list@python.org>
 <4bd11eec-395a-4484-a991-9fabf12328e1@googlegroups.com>
 <mailman.7495.1393639309.18130.python-list@python.org>
 <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
 <mailman.7502.1393655058.18130.python-list@python.org>
 <cfeaefbf-22d8-478a-8423-2d102a52a2ab@googlegroups.com>
 <mailman.7537.1393711293.18130.python-list@python.org>
 <b50d1c92-deab-481b-bc06-73b32cccd822@googlegroups.com>
 <mailman.7550.1393716131.18130.python-list@python.org>
 <268ea8b1-85a8-4b41-bbe2-b8a13ca0a469@googlegroups.com>
 <CAPTjJmqgh5-n8Fgki+VMd8gRzCW5np64kinKa9_B6eWf8Gv_nA@mail.gmail.com>
Message-ID: <nad-2EE6E0.16555801032014@news.gmane.org>

In article 
<CAPTjJmqgh5-n8Fgki+VMd8gRzCW5np64kinKa9_B6eWf8Gv_nA at mail.gmail.com>,
 Chris Angelico <rosuav at gmail.com> wrote:
> What I would recommend, if you don't feel like setting up NNTP, is to
> subscribe to the mailing list:
> 
> https://mail.python.org/mailman/listinfo/python-list
> 
> All the same content, but via email instead. Take your pick between
> that and a newsreader - whichever's easier to get to work.

Or use one of the multiple interfaces to the group/list provided by 
gmane.org: nntp, web, or (read-only) rss.

http://dir.gmane.org/gmane.comp.python.general

-- 
 Ned Deily,
 nad at acm.org



From swdunning at cox.net  Sat Mar  1 20:11:07 2014
From: swdunning at cox.net (Scott W Dunning)
Date: Sat, 1 Mar 2014 18:11:07 -0700
Subject: Help with "Guess the number" script
In-Reply-To: <YJ7s1n00C3bjUJS01J7tQ2>
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <mailman.7516.1393691734.18130.python-list@python.org>
 <YJ7s1n00C3bjUJS01J7tQ2>
Message-ID: <D9724003-3B31-4B30-AEFF-9AD34F581CB8@cox.net>


On Mar 1, 2014, at 11:03 AM, Susan Aldridge <susanaldridge555 at gmail.com> wrote:
> Try this
> 
> def guess1(upLimit = 100):
>    import random
>    num = random.randint(1,upLimit)
>    count = 0
>    gotIt = False
>    while (not gotIt):
>        print('Guess a number between 1 and', upLimit, ':')
>        guess= int(input())
>        count += 1
>        if guess == num:
>              print('Congrats! You win')
>              gotIt = True
>        elif guess < num:
>              print('Go up!')
>        else:
>              print('Guess less')
>    print('You got it in ', count, 'guesses.')
> 
> guess1(100)
Thanks Susan!  The only problem is he wants us to do it without loops because we haven?t learned them yet. I need to use the variables and function names that he?s given as well.  I think I can make sense of what you wrote though so that should help me a bit.  



From breamoreboy at yahoo.co.uk  Sat Mar  1 20:15:31 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 02 Mar 2014 01:15:31 +0000
Subject: Can global variable be passed into Python function?
In-Reply-To: <nad-2EE6E0.16555801032014@news.gmane.org>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7479.1393613988.18130.python-list@python.org>
 <877g8ff3hn.fsf@elektro.pacujo.net>
 <d5984405-9ad5-4514-98cf-1914a1de7bc8@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <0b414429-74ee-45dd-9465-c87e98c362f2@googlegroups.com>
 <mailman.7485.1393634419.18130.python-list@python.org>
 <4bd11eec-395a-4484-a991-9fabf12328e1@googlegroups.com>
 <mailman.7495.1393639309.18130.python-list@python.org>
 <2633c4d3-e8cc-47fa-b22a-48dab2ef1a29@googlegroups.com>
 <mailman.7502.1393655058.18130.python-list@python.org>
 <cfeaefbf-22d8-478a-8423-2d102a52a2ab@googlegroups.com>
 <mailman.7537.1393711293.18130.python-list@python.org>
 <b50d1c92-deab-481b-bc06-73b32cccd822@googlegroups.com>
 <mailman.7550.1393716131.18130.python-list@python.org>
 <268ea8b1-85a8-4b41-bbe2-b8a13ca0a469@googlegroups.com>
 <CAPTjJmqgh5-n8Fgki+VMd8gRzCW5np64kinKa9_B6eWf8Gv_nA@mail.gmail.com>
 <nad-2EE6E0.16555801032014@news.gmane.org>
Message-ID: <leu0n9$oj4$1@ger.gmane.org>

On 02/03/2014 00:55, Ned Deily wrote:
> In article
> <CAPTjJmqgh5-n8Fgki+VMd8gRzCW5np64kinKa9_B6eWf8Gv_nA at mail.gmail.com>,
>   Chris Angelico <rosuav at gmail.com> wrote:
>> What I would recommend, if you don't feel like setting up NNTP, is to
>> subscribe to the mailing list:
>>
>> https://mail.python.org/mailman/listinfo/python-list
>>
>> All the same content, but via email instead. Take your pick between
>> that and a newsreader - whichever's easier to get to work.
>
> Or use one of the multiple interfaces to the group/list provided by
> gmane.org: nntp, web, or (read-only) rss.
>
> http://dir.gmane.org/gmane.comp.python.general
>

This mechanism has the added advantage of being a one stop shop.  Not 
only can you subscribe to hundreds of Python lists there is also a setup 
that lets you take feeds from numerous Python blogs.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Sat Mar  1 20:16:10 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 12:16:10 +1100
Subject: Help with "Guess the number" script
In-Reply-To: <D9724003-3B31-4B30-AEFF-9AD34F581CB8@cox.net>
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <mailman.7516.1393691734.18130.python-list@python.org>
 <D9724003-3B31-4B30-AEFF-9AD34F581CB8@cox.net>
Message-ID: <CAPTjJmoLUchui0SGZKUxkhYDBC++YJnCDNGaPQwii6770ABT1g@mail.gmail.com>

On Sun, Mar 2, 2014 at 12:11 PM, Scott W Dunning <swdunning at cox.net> wrote:
>>    print('You got it in ', count, 'guesses.')
>>
> Thanks Susan!  The only problem is he wants us to do it without loops because we haven?t learned them yet. I need to use the variables and function names that he?s given as well.  I think I can make sense of what you wrote though so that should help me a bit.
>

Another consideration: Susan's code is written for Python 3, but you
seemed to be using Python 2. You'll find that the code won't even run
on your version of Python.

(If you have the chance, ask if the course writer would consider
updating it to use Python 3. There's getting to be less and less
reason to use Python 2 for any new projects; when you start a brand
new system, you should be using Python 3 unless there's something
holding you on the old version. So it's correspondingly more useful to
learn Py3.)

ChrisA


From eric.jacoboni at gmail.com  Sat Mar  1 21:04:32 2014
From: eric.jacoboni at gmail.com (Eric Jacoboni)
Date: Sun, 02 Mar 2014 03:04:32 +0100
Subject: Tuples and immutability
In-Reply-To: <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>
Message-ID: <leu3jg$1gqu$1@cabale.usenet-fr.net>

Le 01/03/2014 22:21, Mark H. Harris a ?crit :
> The point I'm trying to make with this post is that  s[2]+=[46]   and
> s[2]=s[2]+[46]  are handled inconsistently.  

For my own, the fact that, in Python, a_liste += e_elt gives a different
result than a_list = a_list + e_elt is a big source of trouble...
I don't really find a good reason to justify that : a_list += "spam"
gives a valid result, when a_list = a_list + "spam" is not allowed. Why
the former is like a_list.extend() in the first place ? (well, it's not
exactly an extend() as extend returns None, not +=).

And if both operations were equivalent, i think my initial question
about tuples will be clear and the behavio(u)r would me more consistent
for me :

tu = (10, [10, 30])
tu[1] = tu[1] + [20]                    <-- Big mistake!
TypeError: 'tuple' object does not support item assignment  <-- ok
tu
(10, [10, 30])                          <-- ok too...

In fact, i think i'm gonna forget += on lists :)



From harrismh777 at gmail.com  Sat Mar  1 21:15:10 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Sat, 1 Mar 2014 18:15:10 -0800 (PST)
Subject: Tuples and immutability
In-Reply-To: <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>
Message-ID: <ee51bda4-6700-43b2-8e24-e32043164d25@googlegroups.com>

On Saturday, March 1, 2014 3:21:44 PM UTC-6, Mark H. Harris wrote:
> On Friday, February 28, 2014 11:16:18 PM UTC-6, Ian wrote:

hi Ian,  I thought of something else after I slept on it, so to speak. 

Consider this: 

>>> s=(2,3,[42,43,44],7) 
>>> s[2] 
[42, 43, 44] 
>>> 

s[2] is a list. We should be able to change s[2] even though its within a tuple, 
like this: 

[42, 43, 44] 
>>> s[2].append(45) 
>>> s[2] 
[42, 43, 44, 45]       <===== no error 
>>> 

or like this: 

>>> s[2] 
[42, 43, 44, 45] 
>>> s[2]=s[2]+[46] 
Traceback (most recent call last): 
  File "<pyshell#8>", line 1, in <module> 
    s[2]=s[2]+[46]                    <==========error,  but look below====== 
TypeError: 'tuple' object does not support item assignment 
>>> 
>>> s[2] 
[42, 43, 44, 45]        <=========also no change to list  !! 
>>> 

The point I'm trying to make with this post is that  s[2]+=[46]  
and  s[2]=s[2]+[46]  are handled inconsistently.  In each case 
(whether the list is part of a tuple or not)  s[2]  is a valid 
list and should be mutable.   In every case, in fact, it is.  
In each case, in fact, the change might occur.  But, the change 
occurs in the first case (append) without an error.  The change 
occurs in the next case too (+=) but with an error not related 
to the tuple.  The change does not occur in the third case
(s=s+ with an error) but the list is not changed ! 

We all know this is not good. We also all know that its because 
of implementation details the user/coder should not need to know.  

QED:  a bug. 

Having slept on it, I am remembering my Zen of Python:  Errors 
should never pass silently, unless explicitly silenced.  It looks 
to me like  (+=)  in this case is not being handled correctly 
under the covers.  At any rate the three scenarios of trying to 
change a mutable list as an immutable tuple item should be handled 
consistently.  
Either we can change the tuple item (if its a list) or we can't.  
Also, if we cannot then the expected error should 
be consistent. 

Cheers 


Hi ,  I'm experimenting a bit with TextWrangler and gg to see if I can 
at least solve my double spacing and wrap problems with cut
a paste for the moment.

Looks ok?

Thanks


From harrismh777 at gmail.com  Sat Mar  1 21:28:21 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Sat, 1 Mar 2014 18:28:21 -0800 (PST)
Subject: Tuples and immutability
In-Reply-To: <leu3jg$1gqu$1@cabale.usenet-fr.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>
 <leu3jg$1gqu$1@cabale.usenet-fr.net>
Message-ID: <a727bf16-9a42-4322-9f5d-90bc2a7dbfc4@googlegroups.com>

On Saturday, March 1, 2014 8:04:32 PM UTC-6, Eric Jacoboni wrote:
> 
> 
> In fact, i think i'm gonna forget += on lists :)

hi Eric, well, that might be extreme, but you certainly want to avoid
trying to change an immutable. Something you might want to consider
is trying something like creating a new immutable. In the example we've 
been looking at I think I would change the tuple list item with an append();
however, you might try building a new tuple instead of trying to change 
an existing tuple item.
I must admit that I would never have found this bug myself, because I don't
try to change tuples (at all). Anyway, I'm glad you found it -- we all learn
and that's the good news.

Cheers


From swdunning at cox.net  Sat Mar  1 20:06:09 2014
From: swdunning at cox.net (Scott W Dunning)
Date: Sat, 1 Mar 2014 18:06:09 -0700
Subject: Help with "Guess the number" script
In-Reply-To: <YGdh1n00C3bjUJS01GdiJ5>
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <YGdh1n00C3bjUJS01GdiJ5>
Message-ID: <D5517554-EB36-48D5-82BA-33247F11A4AE@cox.net>


On Mar 1, 2014, at 9:35 AM, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> 	Without loops, one part of your assignment is going to be tedious,
> unless the intent is to only allow for one guess per run.
No, 10 guesses per game.  Yes very tedious and repetative.
> 
>> from random import randrange
>> randrange(1, 101)
> 
> 	You generated a random number and then threw it away.
>> 
>> from random import seed
>> seed(129)
I do not know what seed is.  The directions in the begining said to do that I guess to test the code through out writing it?  This is what the directions for that part said.
At the top of your file, import the randrange function from the random module. In order to test this module I also want you to import the seed function from the random module. Immediately after importing it I want you to call the seed function with an argument of 129. By calling the seed function we ensure that the sequence of random numbers you generate will exactly match the ones used in this document. 

> 
> 	Now you are seeding the random number generator but never generate a
> new number after it.
> 
>> 
>> def print_description():
>>   print """Welcome to Guess the Number.
>>   I have seleted a secret number in the range 1 ... 100.
>>   You must guess the number within 10 tries.
>>   I will tell you if you ar high or low, and
>>   I will tell you if you are hot or cold.\n"""
>> 
>> def get_guess(guess_number):
>>   print "(",guess_number,")""Plese enter a guess:"
>>   current_guess = raw_input()
>>   return int(guess_number)
> 
> 	You're returning the counter of how many guesses have been made, and
> dropping the player's guess into the trash
I actually do not understand what you mean here.  Should I get rid of the current_guess line completely?  Should it look more like this;

def get_guess(guess_number):
	raw_input(?Please enter a guess?)
	guess_number = int(guess_number)
	return (guess_number)
get_guess(1)
> 
>> 
>> def main():
>>   print_description()
>>   secret = 50
> 
> 	That's supposed to be the random number, isn't it?
Yes it is, I put 50 there because I was going to try and test it.  I think it should be secret = randrange(1,101) right?
> 
>>   current_guess = 1
>>   get_guess(1)
> 
> 	You drop the return value into the trash
> 
>>   if current_guess != secret():
> 
> 	You are /calling/ a function called secret -- which doesn't exist,
> since you bound it to the integer value 50; And current_guess doesn't exist
> in this function either.
> 
>>       print "Congratulations you win!!"
> 
> 
> 	Read the documentation on how function calls and return values operate.
> Hint: you need to do something with the returned value /at the point where
> you call the function/.
Hmm, ok I?ll try and find what I?m missing.

> 
> 	And -- as has been mentioned; these mistakes are better served in the
> tutor list, as they would be mistakes in /any/ common programming language.
> -- 
> 	
Yes, I?m sorry I completely forgot.  I?ll repost there and go that route.  Thanks though!


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From davea at davea.name  Sat Mar  1 22:04:13 2014
From: davea at davea.name (Dave Angel)
Date: Sat, 1 Mar 2014 22:04:13 -0500 (EST)
Subject: Boxes of O's
References: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>
 <mailman.7529.1393701408.18130.python-list@python.org>
 <31bde8f6-25a6-484f-af6b-bbef7f7a0fdf@googlegroups.com>
Message-ID: <leu6r2$c62$1@ger.gmane.org>

 geniusrko at gmail.com Wrote in message:
> Well, This is what i got 
> 
> n = int(input("enter number of o: "))
> 
> for i in range(n):
>     print("O", end = '')
>     for j in range(n* 2):
>         print("O", end = '')
>     
>     print()
> 

Are you permitted to write and call functions? If so, then write
 functions to solve pieces of the problem, and call those
 functions from your main one.  That's called factoring,  and is
 an important tool.

In this case,  one function could print a row of 'o' of length
 siz, while the second one print a 'hollow' row. Then your main
 calls first, then loops calling hollow, then calls first
 again.

-- 
DaveA



From davea at davea.name  Sat Mar  1 23:02:19 2014
From: davea at davea.name (Dave Angel)
Date: Sat, 1 Mar 2014 23:02:19 -0500 (EST)
Subject: [OT] Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com>
Message-ID: <leua81$fjj$1@ger.gmane.org>

 Grant Edwards <invalid at invalid.invalid> Wrote in message:
> On 2014-02-24, Michael Torrie <torriem at gmail.com> wrote:
>
>>
>> Why would you think that? The address of the start of your malloc'ed
>> structure is the same as the address of the first element.  Surely
>> this is logical?
> 
> Not only is it logical, the C standard explicitly requires it.  Here's
> a second-hand citation since I don't happend to have an actual copy of
> the standard on hand:
> 
>     C1x ???6.7.2.1.13:
> 
>        A pointer to a structure object, suitably converted, points to
>        its initial member ... and vice versa. There may be unnamed
>        padding within a structure object, but not at its beginning.

The quote you make from the C standard doesn't mention malloc,  so
 you're arguing different things. It's not the compiler that casts
 the malloc return value to the struct type.

C++ does implicitly convert the result,  and the return value of
 new already has the struct type. But the runtime stores at least
 two kinds of overhead on occasion,  the array size, and the
 vtable. So the malloc address can not be assumed to match the
 struct beginning.  (Not even considering that one can override
 operator new at two levels)

Glad python doesn't have any of this mess.


-- 
DaveA



From rosuav at gmail.com  Sat Mar  1 23:17:21 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 15:17:21 +1100
Subject: [OT] Can global variable be passed into Python function?
In-Reply-To: <leua81$fjj$1@ger.gmane.org>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com> <leua81$fjj$1@ger.gmane.org>
Message-ID: <CAPTjJmpeLq_7R=Z5J14dpny6XJ0xx-8CnueMJ02pcnDsULZTdg@mail.gmail.com>

On Sun, Mar 2, 2014 at 3:02 PM, Dave Angel <davea at davea.name> wrote:
> The quote you make from the C standard doesn't mention malloc,  so
>  you're arguing different things. It's not the compiler that casts
>  the malloc return value to the struct type.
>
> C++ does implicitly convert the result,  and the return value of
>  new already has the struct type. But the runtime stores at least
>  two kinds of overhead on occasion,  the array size, and the
>  vtable. So the malloc address can not be assumed to match the
>  struct beginning.  (Not even considering that one can override

Whatever pointer malloc returns is the beginning of the *usable*
space. Any overhead for array size etc has to be before that; a
virtual function table pointer would be inside that space, but that's
very much compiler-dependent.

ChrisA


From greg.ewing at canterbury.ac.nz  Sat Mar  1 23:20:08 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Sun, 02 Mar 2014 17:20:08 +1300
Subject: posting code snippets
In-Reply-To: <leq6j9$mnb$2@reader1.panix.com>
References: <e77aff42-6ec3-4749-9683-6ebb2a33ac1a@googlegroups.com>
 <85ppm8nqx7.fsf@benfinney.id.au>
 <mailman.7458.1393566098.18130.python-list@python.org>
 <leq6j9$mnb$2@reader1.panix.com>
Message-ID: <bnfprfFpk0gU1@mid.individual.net>

Grant Edwards wrote:

> You drag out the lab scope, logic analyzer, spectrum analyzer, sweep
> generator, strip plotter, and the machine that goes "ping".  You start
> to get everything set up to nail that problem securely to the
> dissecting board.  Long before you actually get to that point, the
> problem becomes intimidated and reveals itself and a solution.

"No! No! Not the comfy spectrum analyser! I give up!"

-- 
Greg


From frank at chagford.com  Sun Mar  2 00:51:11 2014
From: frank at chagford.com (Frank Millman)
Date: Sun, 2 Mar 2014 07:51:11 +0200
Subject: Mac vs. Linux for Python Development
References: <2465a8c7-ce0e-4606-ad3b-9135c96e3e4c@googlegroups.com>
 <4e741358-ce12-40ac-97b8-3bbbf2d6ddca@googlegroups.com>
 <CAPTjJmrBU9K0aoJyCUmif1FCExtbsuq27pGxiRvyNd=yVn-D5g@mail.gmail.com>
Message-ID: <leugs1$68d$1@ger.gmane.org>


"Chris Angelico" <rosuav at gmail.com> wrote in message 
news:CAPTjJmrBU9K0aoJyCUmif1FCExtbsuq27pGxiRvyNd=yVn-D5g at mail.gmail.com...
>
> The point of this thread isn't really about Windows, so I'll try to
> keep it brief, but there are a couple of things I should clarify. The
> first one is about the 4+ second import time for decimal. I cited
> that, recently, and comparing that with "almost instantaneous" on
> Debian (which is what I experience) isn't entirely fair, because it's
> more about cold cache versus warm cache. (When I shut down IDLE and
> fire it up again, I get sub-second import time. Not as fast as the "so
> quick as to be immeasurable" that my Debian box gave, but still
> quicker than the 4ish second cold cache.)
>

Which version are you talking about?

I have an old, slow box running Windows Server 2003 and python 3.3.2.

I have just booted it up now, called up a command prompt, typed 'python' to 
start the interpreter, and typed 'import decimal'. The interpreter prompt 
re-appeared in the blink of an eye.

Are you talking about something else?

Frank Millman





From rosuav at gmail.com  Sun Mar  2 01:57:04 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 17:57:04 +1100
Subject: Mac vs. Linux for Python Development
In-Reply-To: <leugs1$68d$1@ger.gmane.org>
References: <2465a8c7-ce0e-4606-ad3b-9135c96e3e4c@googlegroups.com>
 <4e741358-ce12-40ac-97b8-3bbbf2d6ddca@googlegroups.com>
 <CAPTjJmrBU9K0aoJyCUmif1FCExtbsuq27pGxiRvyNd=yVn-D5g@mail.gmail.com>
 <leugs1$68d$1@ger.gmane.org>
Message-ID: <CAPTjJmrmJjiGMfqui=PpJco7LjtqVpUjj=XNmTYbYQEmxG3fmw@mail.gmail.com>

On Sun, Mar 2, 2014 at 4:51 PM, Frank Millman <frank at chagford.com> wrote:
> Which version are you talking about?
>
> I have an old, slow box running Windows Server 2003 and python 3.3.2.
>
> I have just booted it up now, called up a command prompt, typed 'python' to
> start the interpreter, and typed 'import decimal'. The interpreter prompt
> re-appeared in the blink of an eye.
>
> Are you talking about something else?

I did it in IDLE, which might have added a bit, but not hugely. It was
3.4.0, so the module in both cases is the C-accelerated version. My
suspicion is that you've used the decimal module already on that
system, so you had a warm cache. When I repeat the exercise, I get
sub-second load times (usually of the order of 100-200ms); the
difference between that and your "blink of an eye" would be to do with
exactness of measurement, CPU/HDD performance, etc, etc, etc.

ChrisA


From cs at zip.com.au  Sun Mar  2 01:32:12 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Sun, 2 Mar 2014 17:32:12 +1100
Subject: How to run multiple virtualenv in product server
In-Reply-To: <d07105f4-584e-4cd8-8c53-235f2de9dd86@googlegroups.com>
References: <d07105f4-584e-4cd8-8c53-235f2de9dd86@googlegroups.com>
Message-ID: <20140302063212.GA46253@cskk.homeip.net>

On 27Feb2014 07:29, YE SHANG <hendikoy at gmail.com> wrote:
> I'm starting to learn virtualenv, I wonder how run python project developed in virtualenv.
> 
> Here is my situation, there is a server we can access with a common user name and password, there are many py scripts wrote by different people on this server.
> 
> If I develop my python project with virtualenv, could I run it in product server??

If you are suggesting that you are developing on a different machine
from the production server, then you probably need to install a
virtualenv on the production server equivalent to the one you are
using on your development machine.
-- 
Cameron Simpson <cs at zip.com.au>

Anagram: Information superhighway <==> I'm on a huge wispy rhino fart.


From frank at chagford.com  Sun Mar  2 02:35:29 2014
From: frank at chagford.com (Frank Millman)
Date: Sun, 2 Mar 2014 09:35:29 +0200
Subject: Mac vs. Linux for Python Development
References: <2465a8c7-ce0e-4606-ad3b-9135c96e3e4c@googlegroups.com>
 <4e741358-ce12-40ac-97b8-3bbbf2d6ddca@googlegroups.com>
 <CAPTjJmrBU9K0aoJyCUmif1FCExtbsuq27pGxiRvyNd=yVn-D5g@mail.gmail.com>
 <leugs1$68d$1@ger.gmane.org>
 <CAPTjJmrmJjiGMfqui=PpJco7LjtqVpUjj=XNmTYbYQEmxG3fmw@mail.gmail.com>
Message-ID: <leumvj$olt$1@ger.gmane.org>


"Chris Angelico" <rosuav at gmail.com> wrote in message
news:CAPTjJmrmJjiGMfqui=PpJco7LjtqVpUjj=XNmTYbYQEmxG3fmw at mail.gmail.com...
> On Sun, Mar 2, 2014 at 4:51 PM, Frank Millman <frank at chagford.com> wrote:
>> Which version are you talking about?
>>
>> I have an old, slow box running Windows Server 2003 and python 3.3.2.
>>
>> I have just booted it up now, called up a command prompt, typed 'python'
>> to
>> start the interpreter, and typed 'import decimal'. The interpreter prompt
>> re-appeared in the blink of an eye.
>>
>> Are you talking about something else?
>
> I did it in IDLE, which might have added a bit, but not hugely. It was
> 3.4.0, so the module in both cases is the C-accelerated version. My
> suspicion is that you've used the decimal module already on that
> system, so you had a warm cache. When I repeat the exercise, I get
> sub-second load times (usually of the order of 100-200ms); the
> difference between that and your "blink of an eye" would be to do with
> exactness of measurement, CPU/HDD performance, etc, etc, etc.
>

I assume by 'warm cache' you mean that I had used the decimal module before 
and not switched the machine off before trying the above exercise.

In my case, the machine was switched off before I started. I switched it on 
and executed the above steps.

To be slightly more precise, instead of 'the blink of an eye', I estimate it 
was between 250-500 ms. If I close the interpreter and start it up again, it 
takes maybe 100-200ms.

Just to be sure, I switched the machine off and on again, and repeated the 
exercise. Starting the interpreter for the first time takes 1.5 - 2 seconds. 
Importing decimal for the first time takes less than 500ms.

Frank





From orgnut at yahoo.com  Sun Mar  2 02:38:08 2014
From: orgnut at yahoo.com (Larry Hudson)
Date: Sat, 01 Mar 2014 23:38:08 -0800
Subject: Help with "Guess the number" script
In-Reply-To: <mailman.7555.1393722671.18130.python-list@python.org>
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <mailman.7516.1393691734.18130.python-list@python.org>
 <YJ7s1n00C3bjUJS01J7tQ2>
 <mailman.7555.1393722671.18130.python-list@python.org>
Message-ID: <1ZidnQpoVoB9Qo_OnZ2dnUVZ_rmdnZ2d@giganews.com>

On 03/01/2014 05:11 PM, Scott W Dunning wrote:
>
> On Mar 1, 2014, at 11:03 AM, Susan Aldridge <susanaldridge555 at gmail.com> wrote:
>> Try this
>>
>> def guess1(upLimit = 100):
>>     import random
>>     num = random.randint(1,upLimit)
>>     count = 0
>>     gotIt = False
>>     while (not gotIt):
>>         print('Guess a number between 1 and', upLimit, ':')
>>         guess= int(input())
>>         count += 1
>>         if guess == num:
>>               print('Congrats! You win')
>>               gotIt = True
>>         elif guess < num:
>>               print('Go up!')
>>         else:
>>               print('Guess less')
>>     print('You got it in ', count, 'guesses.')
>>
>> guess1(100)
> Thanks Susan!  The only problem is he wants us to do it without loops because we haven?t learned them yet. I need to use the variables and function names that he?s given as well.  I think I can make sense of what you wrote though so that should help me a bit.
>

Another 'problem' is what you failed to mention in your post, but is apparent from the 
instructions that you posted -- this assignment is NOT the complete program, just the beginning 
of one.  Your instructor obviously wants you to work on (and understand) this program fragment 
before continuing with the rest of it.

      -=- Larry -=-



From marko at pacujo.net  Sun Mar  2 03:00:36 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 02 Mar 2014 10:00:36 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7465.1393585687.18130.python-list@python.org>
 <87y50vwjq4.fsf@elektro.pacujo.net>
 <mailman.7468.1393595250.18130.python-list@python.org>
 <87d2i7wbxs.fsf@elektro.pacujo.net>
 <roy-590D18.09433028022014@news.panix.com>
Message-ID: <87bnxp58t7.fsf@elektro.pacujo.net>

Roy Smith <roy at panix.com>:

> Python already has a switch statement.  It's just spelled funny...
>
> [...]
>
> try:
>    raise value
> except Case1:
>    print "did case 1"
> except (Case2, Case3):
>    print "did either case 2 or 3"
> else:
>    print "did default"

Not bad! Definitely worth considering.

> No fall-through, however.

Fall-trough is an unfortunate C syntax accident, not a feature worth
emulating.


Marko


From marko at pacujo.net  Sun Mar  2 03:00:39 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 02 Mar 2014 10:00:39 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7465.1393585687.18130.python-list@python.org>
 <87y50vwjq4.fsf@elektro.pacujo.net>
 <mailman.7468.1393595250.18130.python-list@python.org>
 <87d2i7wbxs.fsf@elektro.pacujo.net>
 <mailman.7470.1393598262.18130.python-list@python.org>
 <877g8fgsr1.fsf@elektro.pacujo.net> <leqcb4$p6m$1@reader1.panix.com>
Message-ID: <874n3h58t4.fsf@elektro.pacujo.net>

Grant Edwards <invalid at invalid.invalid>:

> any decent compiler should be able to generate the same code for a
> switch statement and for an equivalent chained if/else.

It's not so easy to be decent, especially when it comes to a language as
dynamic as Python.


Marko


From marko at pacujo.net  Sun Mar  2 03:03:18 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 02 Mar 2014 10:03:18 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7512.1393679028.18130.python-list@python.org>
 <87r46l96j6.fsf@elektro.pacujo.net>
 <mailman.7545.1393713311.18130.python-list@python.org>
Message-ID: <87zjl93u49.fsf@elektro.pacujo.net>

Ben Finney <ben+python at benfinney.id.au>:

> The unreliability is ?will objects defined elsewhere have a different
> identity??

That question is not interesting in my context, and has no bearing on
the correctness of the program.


Marko


From steve+comp.lang.python at pearwood.info  Sun Mar  2 03:35:23 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 02 Mar 2014 08:35:23 GMT
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
Message-ID: <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Sat, 01 Mar 2014 19:29:41 +0200, Marko Rauhamaa wrote:

> Michael Torrie <torriem at gmail.com>:
> 
>> No, '==' works fine no matter what objects you assign to your state
>> variables.
> 
> Well, it doesn't since
> 
>    >>> a = float("nan")
>    >>> a is a
>    True
>    >>> a == a
>    False

No, that is working correctly, so the comment that equals works fine is 
correct: returning False is the correct thing to do if one or both of the 
objects are a NAN. NANs are supposed to compare unequal to everything, 
including themselves.

The is operator and the == operator do not have the same purpose and they 
do not do the same thing. "is" should not be considered an improved == 
without the quirks, this is not PHP and we're not comparing == and ===. 
The argument here is not about which operator performs the check we want, 
but over what check we want: do we want an identity test or an equality 
test?



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From marko at pacujo.net  Sun Mar  2 04:35:43 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 02 Mar 2014 11:35:43 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
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 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87ha7h9c40.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> On Sat, 01 Mar 2014 19:29:41 +0200, Marko Rauhamaa wrote:
>> Michael Torrie <torriem at gmail.com>:
>>> No, '==' works fine no matter what objects you assign to your state
>>> variables.
>> 
>> Well, it doesn't since
>> 
>>    >>> a = float("nan")
>>    >>> a is a
>>    True
>>    >>> a == a
>>    False
>
> No, that is working correctly, so the comment that equals works fine
> is correct: returning False is the correct thing to do if one or both
> of the objects are a NAN. NANs are supposed to compare unequal to
> everything, including themselves.

Nobody is saying there's a bug in the implementation of "==". I'm just
saying "==" cannot be taken as a universal superset of "is". Therefore
a program cannot blindly use "==" to test for identity.

That's why "==" is a bit fishy. It immediately raises the question: what
does it mean for a == b, especially since the exact implementation of a
and b are intended to be opaque.

Example:

The os module defines the constants os.SEEK_SET, os.SEEK_CUR and
os.SEEK_END that can be used as arguments for os.lseek(). Must those
constants be used, or can a regular integer be used instead? The
documentation clearly states that integers can be used:

   SEEK_SET or 0 to set the position relative to the beginning of the
   file; SEEK_CUR or 1 to set it relative to the current position;
   SEEK_END or 2 to set it relative to the end of the file.

However, on the same reference page, os.posix_fadvise() is defined. We
read:

   advice is one of POSIX_FADV_NORMAL, POSIX_FADV_SEQUENTIAL,
   POSIX_FADV_RANDOM, POSIX_FADV_NOREUSE, POSIX_FADV_WILLNEED or
   POSIX_FADV_DONTNEED

and:

    os.POSIX_FADV_NORMAL
    os.POSIX_FADV_SEQUENTIAL
    os.POSIX_FADV_RANDOM
    os.POSIX_FADV_NOREUSE
    os.POSIX_FADV_WILLNEED
    os.POSIX_FADV_DONTNEED

    Flags that can be used in advice in posix_fadvise()

Now, what kinds of object are those constants? We are not supposed to
know or care. We could peek into the implementation, but it would be a
grave mistake to trust the implementation choices in the application.

So in my application code I might set:

   favd_flag = os.POSIX_FADV_RANDOM

in some other part of my code I might want to see how "flag" was set.
Should I use "==" or "is" to test it?

If I take the API documentation on its face value, I *must* use "==" for
os.SEEK*:

    if seek_flag == os.SEEK_END:
        ...

and I *must* use "is" for os.POSIX_FAVD_*:

    if fsavd_flag is os.POSIX_FADV_RANDOM:
        ...

Since, for all I know, os.POSIX_FAVD_RANDOM might return a random value
for __eq__().


Marko


From marko at pacujo.net  Sun Mar  2 04:40:05 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 02 Mar 2014 11:40:05 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
Message-ID: <87d2i59bwq.fsf@elektro.pacujo.net>

Marko Rauhamaa <marko at pacujo.net>:

> If I take the API documentation on its face value, [...]
> I *must* use "is" for os.POSIX_FAVD_*:
>
>     if fsavd_flag is os.POSIX_FADV_RANDOM:
>         ...

However, since a documentation flaw is more than likely, it is even more
prudent to avoid both "==" and "is" and create a set of shadow constants
in the application code:

      if self.fsavd_flag is self.FAVD_RANDOM:
          os.posix_fadvice(fd, offset, len, os.POSIX_FAVD_RANDOM):


Marko


From rosuav at gmail.com  Sun Mar  2 04:58:52 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 20:58:52 +1100
Subject: Mac vs. Linux for Python Development
In-Reply-To: <leumvj$olt$1@ger.gmane.org>
References: <2465a8c7-ce0e-4606-ad3b-9135c96e3e4c@googlegroups.com>
 <4e741358-ce12-40ac-97b8-3bbbf2d6ddca@googlegroups.com>
 <CAPTjJmrBU9K0aoJyCUmif1FCExtbsuq27pGxiRvyNd=yVn-D5g@mail.gmail.com>
 <leugs1$68d$1@ger.gmane.org>
 <CAPTjJmrmJjiGMfqui=PpJco7LjtqVpUjj=XNmTYbYQEmxG3fmw@mail.gmail.com>
 <leumvj$olt$1@ger.gmane.org>
Message-ID: <CAPTjJmoZ-fdZikwE9rmYX-d3duW2pCWxOGWtrzgDzUd=ZUmiCw@mail.gmail.com>

On Sun, Mar 2, 2014 at 6:35 PM, Frank Millman <frank at chagford.com> wrote:
> I assume by 'warm cache' you mean that I had used the decimal module before
> and not switched the machine off before trying the above exercise.
>
> In my case, the machine was switched off before I started. I switched it on
> and executed the above steps.

That would be about it, yeah. So that would be a cold cache test.

> To be slightly more precise, instead of 'the blink of an eye', I estimate it
> was between 250-500 ms. If I close the interpreter and start it up again, it
> takes maybe 100-200ms.

Alright, so now we're talking about some other factors on my system
that slow down the cold cache load dramatically. That I can completely
understand; when I originally posted it, I was fully aware that the
exact figures wouldn't be duplicable. 500ms is a major delay to
startup; but what's really significant is the 100-200ms warm cache,
because that one is what's going to be repeated. (Imagine a web server
that periodically restarts its subprocesses - say, every N requests.
Adding 200ms to startup time effectively adds 200/N ms to every
request.)

An awesome disk cache can improve that immensely, though. My Debian
box, warm cache, takes 0.0 seconds to import decimal. But it's a
faster computer overall, so even cold cache it only takes a hundred ms
or so.

> Just to be sure, I switched the machine off and on again, and repeated the
> exercise. Starting the interpreter for the first time takes 1.5 - 2 seconds.
> Importing decimal for the first time takes less than 500ms.

I'm beginning to get a suspicion here that the Windows XP disk cache
actually might have a "most pessimal" state, where it's full of other
stuff. Worse than a cold cache in performance, a cache warmed by
something else. But in any case, the exact figures for cold cache are
almost immaterial compared to a noticeable warm-cache delay - if
there's enough work to be done just loading the .pyc from the disk
cache that it takes visible time, then it would be a problem to force
that to be loaded on every interpreter startup. Which was kinda the
point of my original testing - I wanted to know how much of a penalty
there'd be to moving decimal to built-in.

ChrisA


From rosuav at gmail.com  Sun Mar  2 05:07:39 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 2 Mar 2014 21:07:39 +1100
Subject: Can global variable be passed into Python function?
In-Reply-To: <87ha7h9c40.fsf@elektro.pacujo.net>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpmw=ejJfwHOGWszDi0G7epn6wXK6ZEgtX52xWHQHtp4Q@mail.gmail.com>

On Sun, Mar 2, 2014 at 8:35 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> However, on the same reference page, os.posix_fadvise() is defined. We
> read:
>
>    advice is one of POSIX_FADV_NORMAL, POSIX_FADV_SEQUENTIAL,
>    POSIX_FADV_RANDOM, POSIX_FADV_NOREUSE, POSIX_FADV_WILLNEED or
>    POSIX_FADV_DONTNEED
>
> Now, what kinds of object are those constants? We are not supposed to
> know or care. We could peek into the implementation, but it would be a
> grave mistake to trust the implementation choices in the application.
>
> So in my application code I might set:
>
>    favd_flag = os.POSIX_FADV_RANDOM
>
> in some other part of my code I might want to see how "flag" was set.
> Should I use "==" or "is" to test it?

In the absence of any advice to the contrary, I would use == to test.
The flags are most likely to be, in order:

* An enumeration, in a sufficiently new Python
* Integers
* Strings
* Arbitrary object()s

All of the above will compare correctly with ==, and if someone stuffs
in an object that compares equal to more than one of them, they're
likely to have problems at the far end. If identity is really crucial,
I would expect there to be a comment in the docs.

And there's another thing you can do to test.

>>> import os
>>> type(os.POSIX_FADV_RANDOM)
<class 'int'>

So use ==. If it's later changed and you have to instead use 'is', you
can change your code.

ChrisA


From marko at pacujo.net  Sun Mar  2 05:37:13 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 02 Mar 2014 12:37:13 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
 <mailman.7567.1393754868.18130.python-list@python.org>
Message-ID: <8761nwanty.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> And there's another thing you can do to test.
>
>>>> import os
>>>> type(os.POSIX_FADV_RANDOM)
> <class 'int'>

Is that what you do in your programs?

> So use ==. If it's later changed and you have to instead use 'is', you
> can change your code.

Quite a robust API, huh?

Anyway, you recognize that the API definer is within their rights to
require 'is' semantics for the constants. IOW, the application must use
the given constant objects and nothing that happens to be == to them.

Consequently, the implementer is within their rights to define:

   def __eq__():
       return True


Marko


From stefan_ml at behnel.de  Sun Mar  2 05:41:56 2014
From: stefan_ml at behnel.de (Stefan Behnel)
Date: Sun, 02 Mar 2014 11:41:56 +0100
Subject: why indentation should be part of the syntax
Message-ID: <lev1t8$qt0$1@ger.gmane.org>

Haven't seen any mention of it on this list yet, but since it's such an
obvious flaw in quite a number of programming languages, here's a good
article on the recent security bug in iOS, which was due to accidentally
duplicated code not actually being as indented as it looked:

https://www.imperialviolet.org/2014/02/22/applebug.html

Stefan



From steve+comp.lang.python at pearwood.info  Sun Mar  2 05:44:19 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 02 Mar 2014 10:44:19 GMT
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
Message-ID: <53130b83$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Sun, 02 Mar 2014 11:35:43 +0200, Marko Rauhamaa wrote:

> Nobody is saying there's a bug in the implementation of "==". I'm just
> saying "==" cannot be taken as a universal superset of "is". Therefore a
> program cannot blindly use "==" to test for identity.

Um, yes? Nor can you use ">" to test for identity, or "+", or "%", or any 
other operator other than "is". Why do you think it is a problem that == 
doesn't test for identity? It's not supposed to test for identity.

Why do you want to test for identity? I think I've asked five times now, 
why you care whether a state value has one instance or a thousand 
instances, and you haven't even attempted an answer.



> That's why "==" is a bit fishy. It immediately raises the question: what
> does it mean for a == b, especially since the exact implementation of a
> and b are intended to be opaque.

It means that a equals b. For ints, it means that they have the same 
numeric value. The same applies for floats. For strings, it means that 
they contain the same code points in the same order. And so on. For all 
built-in types, equality is well-defined. For custom types you create 
yourself, the onus is on you to ensure that equality is meaningful and 
well-defined.


> Example:
> 
> The os module defines the constants os.SEEK_SET, os.SEEK_CUR and
> os.SEEK_END that can be used as arguments for os.lseek(). Must those
> constants be used, or can a regular integer be used instead? The
> documentation clearly states that integers can be used:
> 
>    SEEK_SET or 0 to set the position relative to the beginning of the
>    file; SEEK_CUR or 1 to set it relative to the current position;
>    SEEK_END or 2 to set it relative to the end of the file.
> 
> However, on the same reference page, os.posix_fadvise() is defined. We
> read:
> 
>    advice is one of POSIX_FADV_NORMAL, POSIX_FADV_SEQUENTIAL,
>    POSIX_FADV_RANDOM, POSIX_FADV_NOREUSE, POSIX_FADV_WILLNEED or
>    POSIX_FADV_DONTNEED
> 
> and:
> 
>     os.POSIX_FADV_NORMAL
>     os.POSIX_FADV_SEQUENTIAL
>     os.POSIX_FADV_RANDOM
>     os.POSIX_FADV_NOREUSE
>     os.POSIX_FADV_WILLNEED
>     os.POSIX_FADV_DONTNEED
> 
>     Flags that can be used in advice in posix_fadvise()
> 
> Now, what kinds of object are those constants? We are not supposed to
> know or care.

Incorrect. We are supposed to know and care.

os.posix is exactly the sort of library I mentioned earlier when I said 
sometimes you're constrained by compatibility with some other system. In 
this case, the os module is explicitly designed to be compatible with the 
POSIX interface, which is defined to use certain integer values as flags. 
This is not an implementation choice which implementers can change at 
will, it is part of the interface.

The specific *values* possibly may be allowed to vary from platform to 
platform, and since this is C even the definition of "int" may be 
platform specific, but not that fact that they are ints. Hence the value 
of POSIX_FADV_RANDOM could, theoretically, be different under Linux and 
FreeBSD (say). It probably isn't, but it could be. If you hard-code the 
magic number 1 in your code, you're risking the (tiny) chance of it 
failing on some obscure POSIX system. But that doesn't imply that we must 
test for object identity. There could be a million different instances, 
all with the value POSIX_FADV_RANDOM.

Python does not guarantee that there is only a single 1 instance. If you 
want to test whether a value is os.POSIX_FADV_RANDOM, the right way is to 
compare that value for equality with os.POSIX_FADV_RANDOM, not identity.


> We could peek into the implementation, but it would be a
> grave mistake to trust the implementation choices in the application.
> So in my application code I might set:
> 
>    favd_flag = os.POSIX_FADV_RANDOM

A much better choice than hard-coding the magic value 1. But that choice 
has absolutely nothing to do with whether 1 is a singleton or not.


> in some other part of my code I might want to see how "flag" was set.
> Should I use "==" or "is" to test it?

Equals, of course. There is absolutely no question about that. To even 
*think* that you should test it with "is" means that you have completely 
misunderstood what you are doing here. Why are you relying on an 
implementation detail that CPython happens to cache and reuse small 
integers like 1? What happens if you run your code under an 
implementation of Python that doesn't cache small ints? Or if your 
platform happens to set POSIX_FADV_RANDOM to a non-cached value like 
8531201?

Python does not promise that POSIX_FADV_RANDOM will be a singleton value. 
Using "is" is unsafe.


> If I take the API documentation on its face value, I *must* use "==" for
> os.SEEK*:

Correct.


>     if seek_flag == os.SEEK_END:
>         ...
> 
> and I *must* use "is" for os.POSIX_FAVD_*:

Incorrect.


>     if fsavd_flag is os.POSIX_FADV_RANDOM:
>         ...
> 
> Since, for all I know, os.POSIX_FAVD_RANDOM might return a random value
> for __eq__().

For all *you* know, perhaps, but since os.posix_fadvise is a thin wrapper 
around the POSIX C function fadvise, and that is documented as expecting 
ints for the advice parameter, that cannot be the case.

Unfortunately Python has not had the money put into it to make it an ISO 
standard like Java, and so there are certain areas where the behaviour is 
known by common practice but not officially documented. (A bit like 
British common law.) That the os module is a thin wrapper around os-
specific services may not be explicitly stated, but it is nevertheless 
true.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ben+python at benfinney.id.au  Sun Mar  2 05:59:26 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sun, 02 Mar 2014 21:59:26 +1100
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7512.1393679028.18130.python-list@python.org>
 <87r46l96j6.fsf@elektro.pacujo.net>
 <mailman.7545.1393713311.18130.python-list@python.org>
 <87zjl93u49.fsf@elektro.pacujo.net>
Message-ID: <85r46kkgs1.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Ben Finney <ben+python at benfinney.id.au>:
>
> > The unreliability is ?will objects defined elsewhere have a different
> > identity??
>
> That question is not interesting in my context, and has no bearing on
> the correctness of the program.

You keep vacillating between two positions: pick one for the context.

Either you care about object identity in this context, and the above
observation is relevant.

Or, you don't care about object identity in this context, and you should
avoid ?is? and use ?==?.

But you cannot have both.

-- 
 \        ?You know I could rent you out as a decoy for duck hunters?? |
  `\                                                     ?Groucho Marx |
_o__)                                                                  |
Ben Finney



From alister.ware at ntlworld.com  Sun Mar  2 06:25:31 2014
From: alister.ware at ntlworld.com (Alister)
Date: Sun, 02 Mar 2014 11:25:31 GMT
Subject: posting code snippets
References: <e77aff42-6ec3-4749-9683-6ebb2a33ac1a@googlegroups.com>
 <85ppm8nqx7.fsf@benfinney.id.au>
 <mailman.7458.1393566098.18130.python-list@python.org>
 <leq6j9$mnb$2@reader1.panix.com>
 <mailman.7542.1393712199.18130.python-list@python.org>
Message-ID: <LyEQu.14090$Yn3.13272@fx29.am4>

On Sun, 02 Mar 2014 09:16:35 +1100, Chris Angelico wrote:

> On Sat, Mar 1, 2014 at 1:31 AM, Grant Edwards <invalid at invalid.invalid>
> wrote:
>> You drag out the lab scope, logic analyzer, spectrum analyzer, sweep
>> generator, strip plotter, and the machine that goes "ping".  You start
>> to get everything set up to nail that problem securely to the
>> dissecting board.  Long before you actually get to that point, the
>> problem becomes intimidated and reveals itself and a solution.
> 
> *ALL* my machines go ping. It's fundamental to network debugging. I know
> that's not what you meant, but somehow it comes to the same thing. :)
> 
> And yep. That is so absolutely right. Problems know when concealment
> becomes pointless.
> 
> ChrisA

As a maintenance engineer I find there is also an opposite factor in 
operation.
Equipment manufacturers appear to include an "Engineer Proximity 
Detector" in all designs that cause the equipment to work flawlessly when 
triggered.

The issue the customer has been complaining about incessantly never 
occurs whilst there is an engineer on site.




-- 
We're out of slots on the server


From marko at pacujo.net  Sun Mar  2 06:33:11 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 02 Mar 2014 13:33:11 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
 <53130b83$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <871tykal8o.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> On Sun, 02 Mar 2014 11:35:43 +0200, Marko Rauhamaa wrote:
>> Now, what kinds of object are those constants? We are not supposed to
>> know or care.
>
> Incorrect. We are supposed to know and care.

Then, the documentation is seriously flawed. It gives no hint whatsoever
on the nature of those objects.

> os.posix is exactly the sort of library I mentioned earlier when I
> said sometimes you're constrained by compatibility with some other
> system. In this case, the os module is explicitly designed to be
> compatible with the POSIX interface, which is defined to use certain
> integer values as flags. This is not an implementation choice which
> implementers can change at will, it is part of the interface.

The values of those Python constants don't need to have any relationship
with those of the underlying operating system.

> Python does not guarantee that there is only a single 1 instance.

Nobody has ever argued such a thing. I certainly haven't.

However, nothing in the API spec gives you the right to call the
function with an integer.

> If you want to test whether a value is os.POSIX_FADV_RANDOM, the right
> way is to compare that value for equality with os.POSIX_FADV_RANDOM,
> not identity.

That might well be true but is not explicitly or implicitly specified in
the documentation. (The os.SEEK_* constants are explicitly defined.)

>> Since, for all I know, os.POSIX_FAVD_RANDOM might return a random value
>> for __eq__().
>
> For all *you* know, perhaps, but since os.posix_fadvise is a thin
> wrapper around the POSIX C function fadvise, and that is documented as
> expecting ints for the advice parameter, that cannot be the case.

A pretty serious documentation flaw, then. Misleading even.

I take it from the documentation that you *must* use the given constant
objects and not some improvised integers.

> That the os module is a thin wrapper around os- specific services may
> not be explicitly stated, but it is nevertheless true.

The example was given for illustration purposes; any criticism against
the accuracy of the documentation is a sideshow.


Marko


From Bernd.Nawothnig at t-online.de  Sun Mar  2 07:07:02 2014
From: Bernd.Nawothnig at t-online.de (Bernd Nawothnig)
Date: Sun, 2 Mar 2014 13:07:02 +0100
Subject: why indentation should be part of the syntax
References: <mailman.7568.1393756930.18130.python-list@python.org>
Message-ID: <6gjbua-ac9.ln1@bernd.nawothnig.dialin.t-online.de>

On 2014-03-02, Stefan Behnel wrote:
> Haven't seen any mention of it on this list yet, but since it's such an
> obvious flaw in quite a number of programming languages, here's a good
> article on the recent security bug in iOS, which was due to accidentally
> duplicated code not actually being as indented as it looked:
>
> https://www.imperialviolet.org/2014/02/22/applebug.html

The way Perl or Go handles it where it is not possible to omit the
curly braces would have prevented the same error too.




Bernd

-- 
no time toulouse


From gheskett at wdtv.com  Sun Mar  2 07:20:49 2014
From: gheskett at wdtv.com (Gene Heskett)
Date: Sun, 2 Mar 2014 07:20:49 -0500
Subject: posting code snippets
In-Reply-To: <LyEQu.14090$Yn3.13272@fx29.am4>
References: <e77aff42-6ec3-4749-9683-6ebb2a33ac1a@googlegroups.com>
 <mailman.7542.1393712199.18130.python-list@python.org>
 <LyEQu.14090$Yn3.13272@fx29.am4>
Message-ID: <201403020720.50027.gheskett@wdtv.com>

On Sunday 02 March 2014 07:05:06 Alister did opine:

> On Sun, 02 Mar 2014 09:16:35 +1100, Chris Angelico wrote:
> > On Sat, Mar 1, 2014 at 1:31 AM, Grant Edwards
> > <invalid at invalid.invalid>
> > 
> > wrote:
> >> You drag out the lab scope, logic analyzer, spectrum analyzer, sweep
> >> generator, strip plotter, and the machine that goes "ping".  You
> >> start to get everything set up to nail that problem securely to the
> >> dissecting board.  Long before you actually get to that point, the
> >> problem becomes intimidated and reveals itself and a solution.
> > 
> > *ALL* my machines go ping. It's fundamental to network debugging. I
> > know that's not what you meant, but somehow it comes to the same
> > thing. :)
> > 
> > And yep. That is so absolutely right. Problems know when concealment
> > becomes pointless.
> > 
> > ChrisA
> 
> As a maintenance engineer I find there is also an opposite factor in
> operation.
> Equipment manufacturers appear to include an "Engineer Proximity
> Detector" in all designs that cause the equipment to work flawlessly
> when triggered.
> 
> The issue the customer has been complaining about incessantly never
> occurs whilst there is an engineer on site.

Most sensitive when any cover has been opened.  It took me 5 years to find 
an intermittent video insert problem in a piece of Chyron gear, and when I 
found it, I called the guy at Chyron whose name was on the schematic page 
and told him in no uncertain terms that the best part of him ran down his 
mothers leg.  He'd used a spare gate in a quad nand gate package as an 
inverter, a common practice when you need just one more inverter in a 
design.  Nothing at all wrong with the concept, but the idiot left one of 
the two inputs floating, disconnected.  That is an absolute no-no in any 
digital logic circuit, and will bite somebody on the ass, repeatedly. And 
since I could only get at it for not more than 20 minutes at a time because 
of its duties, I am ashamed that it took me 5 years to find it when the fix 
was half an inch of wire wrapping wire to tie it to the other input pin.

There is not a digital logic chip book on the planet that doesn't contain 
warnings about floating inputs.

Yeah, I CAN be one of those to idiots.  As Marion Morrison, aka John Wayne 
was fond of saying in his movies, stupidity should hurt.  And this guy 
deserved to hurt.

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

NOTICE: Will pay 100 USD for an HP-4815A defective but
complete probe assembly.



From ashish.u.panchal at googlemail.com  Sun Mar  2 07:05:14 2014
From: ashish.u.panchal at googlemail.com (Ashish Panchal)
Date: Sun, 2 Mar 2014 17:35:14 +0530
Subject: Can tuples be replaced with lists all the time?
Message-ID: <CAF_cDv9TVhm6HStrgKiEOXX8uy7S94meYPUD8KoWqO6M25tykw@mail.gmail.com>

No, not always. You can use yuples as dictionary key as keys are immutable
and you can't use it as list.
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From ian.g.kelly at gmail.com  Sun Mar  2 07:32:35 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 2 Mar 2014 05:32:35 -0700
Subject: Tuples and immutability
In-Reply-To: <leu3jg$1gqu$1@cabale.usenet-fr.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>
 <leu3jg$1gqu$1@cabale.usenet-fr.net>
Message-ID: <CALwzid=a1hzGxMt_jNxkZNEDm=t7D+7QX0B9=o40SKeXrpTVHQ@mail.gmail.com>

On Sat, Mar 1, 2014 at 7:04 PM, Eric Jacoboni <eric.jacoboni at gmail.com> wrote:
> In fact, i think i'm gonna forget += on lists :)

Well, do what you want, but I think you're taking the wrong lesson
from this.  Don't forget about using += on lists.  Instead, forget
about using assignments, augmented or otherwise, on tuple elements.
Would you expect this to work?

    tup = (1, 2, 3)
    tup[1] += 42

I'm guessing probably not.  So I have a hard time understanding why it
should be expected to work any differently when the tuple element
happens to be a list.  The fact that the list is actually modified I
think is a distraction from the main point: the error indicates that
something illegal happened, not that nothing has changed.  Assignments
just are not allowed on tuple elements, and it doesn't matter what
type they happen to be.


From ned at nedbatchelder.com  Sun Mar  2 07:36:31 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Sun, 02 Mar 2014 07:36:31 -0500
Subject: why indentation should be part of the syntax
In-Reply-To: <lev1t8$qt0$1@ger.gmane.org>
References: <lev1t8$qt0$1@ger.gmane.org>
Message-ID: <lev8k2$ret$1@ger.gmane.org>

On 3/2/14 5:41 AM, Stefan Behnel wrote:
> Haven't seen any mention of it on this list yet, but since it's such an
> obvious flaw in quite a number of programming languages, here's a good
> article on the recent security bug in iOS, which was due to accidentally
> duplicated code not actually being as indented as it looked:
>
> https://www.imperialviolet.org/2014/02/22/applebug.html
>
> Stefan
>

As much as I like indentation as syntax, and am amused by this bug, I'm 
not sure we can chalk it all up to space-vs-brace. After all, who would 
have wanted two goto's in a row even with braces?  It's not like there's 
some engineer at Apple who meant for the code to read like this:

     if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) {
         goto fail;
         goto fail;
     }

This looks to me like a poorly handled merge conflict maybe?  I wonder 
if we'll ever get the details.

-- 
Ned Batchelder, http://nedbatchelder.com



From breamoreboy at yahoo.co.uk  Sun Mar  2 08:00:40 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 02 Mar 2014 13:00:40 +0000
Subject: Can global variable be passed into Python function?
In-Reply-To: <85r46kkgs1.fsf@benfinney.id.au>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7512.1393679028.18130.python-list@python.org>
 <87r46l96j6.fsf@elektro.pacujo.net>
 <mailman.7545.1393713311.18130.python-list@python.org>
 <87zjl93u49.fsf@elektro.pacujo.net> <85r46kkgs1.fsf@benfinney.id.au>
Message-ID: <leva1e$2vv$1@ger.gmane.org>

On 02/03/2014 10:59, Ben Finney wrote:
> Marko Rauhamaa <marko at pacujo.net> writes:
>
>> Ben Finney <ben+python at benfinney.id.au>:
>>
>>> The unreliability is ?will objects defined elsewhere have a different
>>> identity??
>>
>> That question is not interesting in my context, and has no bearing on
>> the correctness of the program.
>
> You keep vacillating between two positions: pick one for the context.
>
> Either you care about object identity in this context, and the above
> observation is relevant.
>
> Or, you don't care about object identity in this context, and you should
> avoid ?is? and use ?==?.
>
> But you cannot have both.
>

Unless you're a troll.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From breamoreboy at yahoo.co.uk  Sun Mar  2 08:04:17 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 02 Mar 2014 13:04:17 +0000
Subject: Can global variable be passed into Python function?
In-Reply-To: <87ha7h9c40.fsf@elektro.pacujo.net>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
Message-ID: <leva87$b7i$1@ger.gmane.org>

On 02/03/2014 09:35, Marko Rauhamaa wrote:
> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
>
>> On Sat, 01 Mar 2014 19:29:41 +0200, Marko Rauhamaa wrote:
>>> Michael Torrie <torriem at gmail.com>:
>>>> No, '==' works fine no matter what objects you assign to your state
>>>> variables.
>>>
>>> Well, it doesn't since
>>>
>>>     >>> a = float("nan")
>>>     >>> a is a
>>>     True
>>>     >>> a == a
>>>     False
>>
>> No, that is working correctly, so the comment that equals works fine
>> is correct: returning False is the correct thing to do if one or both
>> of the objects are a NAN. NANs are supposed to compare unequal to
>> everything, including themselves.
>
> Nobody is saying there's a bug in the implementation of "==". I'm just
> saying "==" cannot be taken as a universal superset of "is". Therefore
> a program cannot blindly use "==" to test for identity.
>
> That's why "==" is a bit fishy. It immediately raises the question: what
> does it mean for a == b, especially since the exact implementation of a
> and b are intended to be opaque.
>
> Example:
>
> The os module defines the constants os.SEEK_SET, os.SEEK_CUR and
> os.SEEK_END that can be used as arguments for os.lseek(). Must those
> constants be used, or can a regular integer be used instead? The
> documentation clearly states that integers can be used:
>
>     SEEK_SET or 0 to set the position relative to the beginning of the
>     file; SEEK_CUR or 1 to set it relative to the current position;
>     SEEK_END or 2 to set it relative to the end of the file.
>
> However, on the same reference page, os.posix_fadvise() is defined. We
> read:
>
>     advice is one of POSIX_FADV_NORMAL, POSIX_FADV_SEQUENTIAL,
>     POSIX_FADV_RANDOM, POSIX_FADV_NOREUSE, POSIX_FADV_WILLNEED or
>     POSIX_FADV_DONTNEED
>
> and:
>
>      os.POSIX_FADV_NORMAL
>      os.POSIX_FADV_SEQUENTIAL
>      os.POSIX_FADV_RANDOM
>      os.POSIX_FADV_NOREUSE
>      os.POSIX_FADV_WILLNEED
>      os.POSIX_FADV_DONTNEED
>
>      Flags that can be used in advice in posix_fadvise()
>
> Now, what kinds of object are those constants? We are not supposed to
> know or care. We could peek into the implementation, but it would be a
> grave mistake to trust the implementation choices in the application.
>
> So in my application code I might set:
>
>     favd_flag = os.POSIX_FADV_RANDOM
>
> in some other part of my code I might want to see how "flag" was set.
> Should I use "==" or "is" to test it?
>
> If I take the API documentation on its face value, I *must* use "==" for
> os.SEEK*:
>
>      if seek_flag == os.SEEK_END:
>          ...
>
> and I *must* use "is" for os.POSIX_FAVD_*:
>
>      if fsavd_flag is os.POSIX_FADV_RANDOM:
>          ...
>
> Since, for all I know, os.POSIX_FAVD_RANDOM might return a random value
> for __eq__().
>
>
> Marko
>

Will you please be kind enough to stop writing this drivel.  You've been 
told repeatedly that you don't know what you're talking about, so have 
the decency to just belt up.  Now try testing these words for identity.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From davea at davea.name  Sun Mar  2 08:22:57 2014
From: davea at davea.name (Dave Angel)
Date: Sun, 2 Mar 2014 08:22:57 -0500 (EST)
Subject: [OT] Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com> <leua81$fjj$1@ger.gmane.org>
 <CAPTjJmpeLq_7R=Z5J14dpny6XJ0xx-8CnueMJ02pcnDsULZTdg@mail.gmail.com>
Message-ID: <levb36$jmk$1@ger.gmane.org>

 Chris Angelico <rosuav at gmail.com> Wrote in message:
> On Sun, Mar 2, 2014 at 3:02 PM, Dave Angel <davea at davea.name> wrote:
>> The quote you make from the C standard doesn't mention malloc,  so
>>  you're arguing different things. It's not the compiler that casts
>>  the malloc return value to the struct type.
>>
>> C++ does implicitly convert the result,  and the return value of
>>  new already has the struct type. But the runtime stores at least
>>  two kinds of overhead on occasion,  the array size, and the
>>  vtable. So the malloc address can not be assumed to match the
>>  struct beginning.  (Not even considering that one can override
> 
> Whatever pointer malloc returns is the beginning of the *usable*
> space. Any overhead for array size etc has to be before that; a
> virtual function table pointer would be inside that space, but that's
> very much compiler-dependent.
> 

Sure,  for some definition of "usable".  Overhead such as block
 size, freelist pointer etc., are obviously outside of the
 returned block.  But the array size that's specified in a call to
 new [], and the vptr, are definitely inside the malloc'ed block,
 and may be before the struct data.

-- 
DaveA



From thrinass at thrinaxodon.thrinassodon  Sun Mar  2 08:28:27 2014
From: thrinass at thrinaxodon.thrinassodon (THRINASSODON1)
Date: Sun, 02 Mar 2014 08:28:27 -0500
Subject: HUMANS HAVE ORIGINS IN THE DEVONIAN, AND YOU KNOW IT!
Message-ID: <levblm$qi2$2@speranza.aioe.org>

================================
 >BREAKING FUCKING NEWS, ASSHOLES!
================================
 >
THRINAXODON JUST FOUND THREE HUMAN FOSSILS FROM DEVONIAN STRATA IN 
GREENLAND; THE FOSSILS WERE A HUMAN FEMUR, KNEECAP, AND SKULLCAP.
 >
THE SMITHSONIAN IS CHASTISING OVER THESE FINDS, DOING EVERYTHING IN 
THEIR POWER TO CENSOR THE TRUTH.
 >
DONATE TO THE BIOLORD9 FOUNDATION TO FIND OUT HOW TO STOP THE 
SMITHSONIAN FROM CENSORING THE TRUTH, AND LET THE TRUTH THAT HUMAN 
EVOLUTION IS A SCAM BE REVEALED!
 >
===========================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/6f501c469c7af24f#

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/3aad75c16afb0b82#

====================================

http://thrinaxodon.wordpress.com/

===================================

THRINAXODON ONLY HAD THIS TO SAY:

"I..I...I...Can't believe it. This completely disproved Darwinian
orthodoxy."

===================================

THE BASTARDS AT THE SMITHSONIAN, AND THE LEAKEY FOUNDATION ARE ERODING
WITH FEAR.

===========================
THESE ASSHOLES ARE GOING TO DIE:
THOMAS AQUINAS;
ALDOUS HUXLEY;
BOB CASANVOVA;
SkyEyes;
DAVID IAIN GRIEG;
MARK ISAAK;
JOHN HARSHAM;
RICHARD NORMAN;
DR. DOOLITTLE;
CHARLES DARWIN;
MARK HORTON;
ERIK SIMPSON;
HYPATIAB7;
PAUL J. GANS;
JILLERY;
WIKI TRIK;
THRINAXODON;
PETER NYIKOS;
RON OKIMOTO;
JOHN S. WILKINS
===========================

THRINAXODON WAS SCOURING ANOTHER DEVONIAN FOSSIL BED, AND FOUND A
HUMAN SKULL, AND A HUMAN FEMUR. HE ANALYSED THE FINDS, AND SAW THAT
THEY WERE NOT NORMAL ROCKS. THESE WERE FOSSILIZED BONES. THEY EVEN HAD
TOOTH MARKS ON THEM. SO, THRINAXODON BROUGHT THEM TO THE LEAKEY
FOUNDATION, THEY UTTERLY DISMISSED IT, AND SAID, "We want to keep
people thinking that humans evolved 2 Ma." THRINAXODON BROUGHT HIS
SWORD, AND SAID, "SCIENCE CORRECTS ITSELF." RICHARD LEAKEY SAID, "That
is a myth, for people to believe in science." THRINAXODON PLANS TO
BRING DOOM TO SCIENCE, ITSELF.

============================

THRINAXODON IS NOW ON REDDIT
-- 
---Thrinaxodon


From eric.jacoboni at gmail.com  Sun Mar  2 08:38:51 2014
From: eric.jacoboni at gmail.com (Eric Jacoboni)
Date: Sun, 02 Mar 2014 14:38:51 +0100
Subject: Tuples and immutability
In-Reply-To: <mailman.7572.1393763606.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>
 <leu3jg$1gqu$1@cabale.usenet-fr.net>
 <mailman.7572.1393763606.18130.python-list@python.org>
Message-ID: <levc9c$2e9t$1@cabale.usenet-fr.net>

Le 02/03/2014 13:32, Ian Kelly a ?crit :
> On Sat, Mar 1, 2014 at 7:04 PM, Eric Jacoboni <eric.jacoboni at gmail.com> wrote:
>> In fact, i think i'm gonna forget += on lists :)
> 
> Well, do what you want, but I think you're taking the wrong lesson
> from this.  Don't forget about using += on lists.  Instead, forget
> about using assignments, augmented or otherwise, on tuple elements.
> Would you expect this to work?

Well, the thing about += on lists that makes me forget it, like i said
in my previous post, is that its behaviour is not consistent with +.

Don't get me wrong: i don't expect that modifying a tuple element works.
That's exactly my point: my initial question was, why it "half works :
it should not work at all". I was thinking that += on lists worked like
update() or extend() : modifying lists in place... It was my mistake

So, yes, i still don't get the point using a += operation, which is not
even consistent with the + operation (see my exemple on "spam" in my
previous post). The + operator to return the modified list and the
update() or extend() methods to do in place replacements are well enough
for my present needs. Maybe, in the future, i will find a use case of +=
for lists which is not covered by others methods, though... Who knows? I
don't doubt that Python designers have made this choice and this
behavior for a good reason: i've just not get it yet.


From breamoreboy at yahoo.co.uk  Sun Mar  2 09:05:35 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 02 Mar 2014 14:05:35 +0000
Subject: Tuples and immutability
In-Reply-To: <levc9c$2e9t$1@cabale.usenet-fr.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>
 <leu3jg$1gqu$1@cabale.usenet-fr.net>
 <mailman.7572.1393763606.18130.python-list@python.org>
 <levc9c$2e9t$1@cabale.usenet-fr.net>
Message-ID: <levdr5$dv0$1@ger.gmane.org>

On 02/03/2014 13:38, Eric Jacoboni wrote:
> Le 02/03/2014 13:32, Ian Kelly a ?crit :
>> On Sat, Mar 1, 2014 at 7:04 PM, Eric Jacoboni <eric.jacoboni at gmail.com> wrote:
>>> In fact, i think i'm gonna forget += on lists :)
>>
>> Well, do what you want, but I think you're taking the wrong lesson
>> from this.  Don't forget about using += on lists.  Instead, forget
>> about using assignments, augmented or otherwise, on tuple elements.
>> Would you expect this to work?
>
> Well, the thing about += on lists that makes me forget it, like i said
> in my previous post, is that its behaviour is not consistent with +.

The behaviour is consistent except when you try to modify a tuple.

>
> Don't get me wrong: i don't expect that modifying a tuple element works.
> That's exactly my point: my initial question was, why it "half works :
> it should not work at all". I was thinking that += on lists worked like
> update() or extend() : modifying lists in place... It was my mistake

I'd like to see you get update to work on a list.  This shows how 
confused you are over this issue.

>
> So, yes, i still don't get the point using a += operation, which is not
> even consistent with the + operation (see my exemple on "spam" in my
> previous post). The + operator to return the modified list and the
> update() or extend() methods to do in place replacements are well enough
> for my present needs. Maybe, in the future, i will find a use case of +=
> for lists which is not covered by others methods, though... Who knows? I
> don't doubt that Python designers have made this choice and this
> behavior for a good reason: i've just not get it yet.
>

All of this comes about because of the known issue with tuples.  Take 
them out of the equation and the behaviour of =, +=, extend and append 
is consistent.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Sun Mar  2 09:08:24 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 01:08:24 +1100
Subject: why indentation should be part of the syntax
In-Reply-To: <lev8k2$ret$1@ger.gmane.org>
References: <lev1t8$qt0$1@ger.gmane.org>
	<lev8k2$ret$1@ger.gmane.org>
Message-ID: <CAPTjJmqfTZz6w9cfOUrMP++A+pKhz1xS+aGdbw_u0T_Tzx=-zg@mail.gmail.com>

On Sun, Mar 2, 2014 at 11:36 PM, Ned Batchelder <ned at nedbatchelder.com> wrote:
> As much as I like indentation as syntax, and am amused by this bug, I'm not
> sure we can chalk it all up to space-vs-brace. After all, who would have
> wanted two goto's in a row even with braces?  It's not like there's some
> engineer at Apple who meant for the code to read like this:
>
>     if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) {
>         goto fail;
>         goto fail;
>     }
>
> This looks to me like a poorly handled merge conflict maybe?  I wonder if
> we'll ever get the details.

Put it this way: If I saw two gotos in a row like that, with or
without braces, I would be firing up gitk or git gui blame or
something to figure out what happened.

But ultimately, it comes down to this: No matter what, the compiler
can't catch every bug. That's why we have peer review, test suites,
and (above all) the magnificent time machine of source control. "What
the <<bleep>> happened here?" becomes "Huh. I see, someone didn't
notice that x and y did a z" when you can see the commit that
introduced something. Indentation-as-syntax doesn't prevent weird
errors from creeping in - look at this one from the Python stdlib:

http://bugs.python.org/issue20729

Notably this bit of code:

        if hasattr(arg, 'iteritems'):
            source = arg.items()
        elif hasattr(arg, 'items'):
            source = arg.items()
        else:
            source = arg


It would take an exceedingly weird set of circumstances for this to
actually matter, but it's something that looks pretty odd in the code,
and no compiler support would help it. Although... to plug my own
proposal... PEP 463 exception expressions might have reduced the
duplication a bit. But it'd still be possible to get something that
looks weird, like:

source = (arg.items()
    except AttributeError: (arg.items()
    except AttributeError: arg))

or, equally weirdly:

source = ((arg.items()
    except AttributeError: arg.items())
    except AttributeError: arg)

There's no "easy fix" for this sort of thing. Maybe a linter could
have been run over the original C code and flagged a warning
(Unexpected indent!), but that's really all. (That actually goes
against the subject line. If the indentation is what matters, you
can't lint it against the braces, you just get the other odd
behaviour.)

ChrisA


From rosuav at gmail.com  Sun Mar  2 08:57:27 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 00:57:27 +1100
Subject: [OT] Can global variable be passed into Python function?
In-Reply-To: <levb36$jmk$1@ger.gmane.org>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com> <leua81$fjj$1@ger.gmane.org>
 <CAPTjJmpeLq_7R=Z5J14dpny6XJ0xx-8CnueMJ02pcnDsULZTdg@mail.gmail.com>
 <levb36$jmk$1@ger.gmane.org>
Message-ID: <CAPTjJmrCXrqZzCrvWm7Bb0yG3wDge=kheLL4w83W79MQ4XKGdg@mail.gmail.com>

On Mon, Mar 3, 2014 at 12:22 AM, Dave Angel <davea at davea.name> wrote:
> Sure,  for some definition of "usable".  Overhead such as block
>  size, freelist pointer etc., are obviously outside of the
>  returned block.  But the array size that's specified in a call to
>  new [], and the vptr, are definitely inside the malloc'ed block,
>  and may be before the struct data.

Hmm. Last I was working with it, the array size to new[] was outside
the block, just as the block size to malloc(). The vptr is part of any
struct/class with virtual functions, and effectively acts as a hidden
class member, so you get one of those inside the block, and it's
included in sizeof.

//Allocated Space: The Final Frontier!
#include <stdio.h> //cout sucks :)

class Foo
{
    int x;
    int y;
    int z;
};

class Bar
{
    int x;
    int y;
    int z;
    virtual int get_x() {return x;}
};

int main()
{
    printf("sizeof(int) = %u\n",sizeof(int));
    printf("sizeof(int*) = %u\n",sizeof(int*));
    printf("sizeof(Foo) = %u\n",sizeof(Foo));
    printf("sizeof(Bar) = %u\n",sizeof(Bar));
    Foo *foo = new Foo[10];
    printf("foo = %p/%p = %u\n",foo,foo+10,(char *)(foo+10)-(char *)foo);
    Bar *bar = new Bar[10];
    printf("bar = %p/%p = %u\n",bar,bar+10,(char *)(bar+10)-(char *)bar);
    return 0;
}


rosuav at sikorsky:~$ g++ frontier.cpp && ./a.out
sizeof(int) = 4
sizeof(int*) = 8
sizeof(Foo) = 12
sizeof(Bar) = 24
foo = 0xf38010/0xf38088 = 120
bar = 0xf38090/0xf38180 = 240



The rules of structs are that they be contiguous, that they be laid
out sequentially, and that any padding needed between structures is at
the end of the previous one (which is why three of 4 bytes makes 12
bytes, but three of 4 bytes plus 8 bytes makes 24 - the eight-byte
pointer has to be aligned on a multiple of eight bytes, so having a
20-byte structure that starts with an 8-byte pointer is a no-no). The
allocated block of memory is, by definition, the same as the pointer
to its first element. As it happens, the pointer bar is not synonymous
with &bar->x, &bar->y, or &bar->z, which means the vptr is at the
beginning of bar, which makes sense; but the compiler's not obliged to
do that, and in some cases may choose not to - for instance, if bar
(with a virtual function) inherited from foo (with none), it might be
convenient to allow a pointer-cast to not change the value of the
pointer. (g++ 4.7.2 still puts the vptr at the beginning of bar in
that case, but other compilers or other versions may differ.)

Array size is outside the block, presumably before it, as &foo[0] is
by definition identical to foo, and there's no room inside the
structure for any spare data. Virtual function table is inside the
block because it's a hidden member of the object (like __class__ in
Python, only better hidden).

ChrisA


From eric.jacoboni at gmail.com  Sun Mar  2 09:17:11 2014
From: eric.jacoboni at gmail.com (Eric Jacoboni)
Date: Sun, 02 Mar 2014 15:17:11 +0100
Subject: Tuples and immutability
In-Reply-To: <mailman.7577.1393769155.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>
 <leu3jg$1gqu$1@cabale.usenet-fr.net>
 <mailman.7572.1393763606.18130.python-list@python.org>
 <levc9c$2e9t$1@cabale.usenet-fr.net>
 <mailman.7577.1393769155.18130.python-list@python.org>
Message-ID: <leveh7$2jh0$1@cabale.usenet-fr.net>

Le 02/03/2014 15:05, Mark Lawrence a ?crit :

> The behaviour is consistent except when you try to modify a tuple.
> 

Not in my opinion...

li = [10, 30]
li = li + "spam"   --> TypeError: can only concatenate list (not "str")
li += "spam"       --> Ok

So, not, that's not what i call consistent.

And it's not related to tuples...

> I'd like to see you get update to work on a list.  This shows how
> confused you are over this issue.

Well, sorry, i wanted to write .append()




From python.list at tim.thechases.com  Sun Mar  2 09:28:34 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Sun, 2 Mar 2014 08:28:34 -0600
Subject: why indentation should be part of the syntax
In-Reply-To: <CAPTjJmqfTZz6w9cfOUrMP++A+pKhz1xS+aGdbw_u0T_Tzx=-zg@mail.gmail.com>
References: <lev1t8$qt0$1@ger.gmane.org> <lev8k2$ret$1@ger.gmane.org>
 <CAPTjJmqfTZz6w9cfOUrMP++A+pKhz1xS+aGdbw_u0T_Tzx=-zg@mail.gmail.com>
Message-ID: <20140302082834.02d8ce42@bigbox.christie.dr>

On 2014-03-03 01:08, Chris Angelico wrote:
> >     if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0)
> > { goto fail;
> >         goto fail;
> >     }
> 
> Put it this way: If I saw two gotos in a row like that, with or
> without braces, I would be firing up gitk or git gui blame or
> something to figure out what happened.

That depends on actually seeing them in the first place :-)

Computers are great -- it's the people interacting with them (both on
the coding-end and the user-end) that cause problems every time ;-)

-tkc





From albert.visser at gmail.com  Sun Mar  2 09:37:44 2014
From: albert.visser at gmail.com (albert visser)
Date: Sun, 02 Mar 2014 15:37:44 +0100
Subject: Tuples and immutability
In-Reply-To: <leveh7$2jh0$1@cabale.usenet-fr.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
 <mailman.7499.1393651028.18130.python-list@python.org>
 <889d371a-c8e3-4d6b-8ba4-d3df61f29b0d@googlegroups.com>
 <leu3jg$1gqu$1@cabale.usenet-fr.net>
 <mailman.7572.1393763606.18130.python-list@python.org>
 <levc9c$2e9t$1@cabale.usenet-fr.net>
 <mailman.7577.1393769155.18130.python-list@python.org>
 <leveh7$2jh0$1@cabale.usenet-fr.net>
Message-ID: <op.xb3mtit77k0gyi@localhost>

On Sun, 02 Mar 2014 15:17:11 +0100, Eric Jacoboni  
<eric.jacoboni at gmail.com> wrote:

> Le 02/03/2014 15:05, Mark Lawrence a ?crit :
>
>> The behaviour is consistent except when you try to modify a tuple.
>>
>
> Not in my opinion...
>
> li = [10, 30]
> li = li + "spam"   --> TypeError: can only concatenate list (not "str")
> li += "spam"       --> Ok
>

possibly because you expect += to take "spam" as a string, but have you  
looked at the result?

In [1]: mylist = ['1', '2']

In [2]: mylist += 'spam'

In [3]: mylist
Out[3]: ['1', '2', 's', 'p', 'a', 'm']

consequently, try adding something that can not be interpreted as a  
sequence:

In [4]: mylist += 3
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-782b544a29d1> in <module>()
----> 1 mylist += 3

TypeError: 'int' object is not iterable


-- 
Vriendelijke groeten / Kind regards,

Albert Visser

Using Opera's mail client: http://www.opera.com/mail/


From roy at panix.com  Sun Mar  2 09:38:50 2014
From: roy at panix.com (Roy Smith)
Date: Sun, 02 Mar 2014 09:38:50 -0500
Subject: why indentation should be part of the syntax
References: <mailman.7568.1393756930.18130.python-list@python.org>
Message-ID: <roy-3F8596.09385002032014@news.panix.com>

In article <mailman.7568.1393756930.18130.python-list at python.org>,
 Stefan Behnel <stefan_ml at behnel.de> wrote:

> Haven't seen any mention of it on this list yet, but since it's such an
> obvious flaw in quite a number of programming languages, here's a good
> article on the recent security bug in iOS, which was due to accidentally
> duplicated code not actually being as indented as it looked:
> 
> https://www.imperialviolet.org/2014/02/22/applebug.html
> 
> Stefan

Hogwash.  What this looks like is two gotos in a row.  Anybody who 
reviewed this code would have thrown up a red flag when they saw two 
gotos in a row.  If anything, the "incorrect" indentation makes it even 
more obvious.  Any static code analyzer would have also caught this as 
an unreachable statement.

Paraphrasing this into Python, you get:

def bogus():
    if SSLHashSHA1.update(hashCtx, serverRandom) != 0:
        raise fail
    if SSLHashSHA1.update(hashCtx, signedParams) != 0:
        raise fail
        raise fail
    if SSLHashSHA1.final(hashCtx, hashOut) != 0:
        raise fail

which is syntactically valid (at least, I can import it), but clearly 
not what the author intended.  So how did Python's indentation rules 
save us?

On the other hand, the Python code was actually a little annoying to 
type in because emacs refused to auto-indent the second raise!  So maybe 
the real rule is to only write code using emacs :-)


From geniusrko at gmail.com  Sun Mar  2 09:43:48 2014
From: geniusrko at gmail.com (geniusrko at gmail.com)
Date: Sun, 2 Mar 2014 06:43:48 -0800 (PST)
Subject: Boxes of O's
In-Reply-To: <mailman.7532.1393703673.18130.python-list@python.org>
References: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>
 <mailman.7529.1393701408.18130.python-list@python.org>
 <31bde8f6-25a6-484f-af6b-bbef7f7a0fdf@googlegroups.com>
 <mailman.7532.1393703673.18130.python-list@python.org>
Message-ID: <729104f4-92f8-48a3-9b7c-e7ba4fb6a38e@googlegroups.com>

I agree with you and really appreciate your experience. But what I was looking for is clues. Thank you anyway


From breamoreboy at yahoo.co.uk  Sun Mar  2 09:56:55 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 02 Mar 2014 14:56:55 +0000
Subject: Boxes of O's
In-Reply-To: <729104f4-92f8-48a3-9b7c-e7ba4fb6a38e@googlegroups.com>
References: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>
 <mailman.7529.1393701408.18130.python-list@python.org>
 <31bde8f6-25a6-484f-af6b-bbef7f7a0fdf@googlegroups.com>
 <mailman.7532.1393703673.18130.python-list@python.org>
 <729104f4-92f8-48a3-9b7c-e7ba4fb6a38e@googlegroups.com>
Message-ID: <levgrd$cj8$1@ger.gmane.org>

On 02/03/2014 14:43, geniusrko at gmail.com wrote:
> I agree with you and really appreciate your experience. But what I was looking for is clues. Thank you anyway
>

Sorry, can't resist this one https://www.youtube.com/watch?v=oaGpaj2nHIo :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From marko at pacujo.net  Sun Mar  2 10:26:46 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 02 Mar 2014 17:26:46 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7465.1393585687.18130.python-list@python.org>
 <87y50vwjq4.fsf@elektro.pacujo.net>
 <mailman.7468.1393595250.18130.python-list@python.org>
 <87d2i7wbxs.fsf@elektro.pacujo.net>
 <roy-590D18.09433028022014@news.panix.com>
 <87bnxp58t7.fsf@elektro.pacujo.net>
Message-ID: <87fvn08vux.fsf@elektro.pacujo.net>

Marko Rauhamaa <marko at pacujo.net>:

> Roy Smith <roy at panix.com>:
>
>> Python already has a switch statement.  It's just spelled funny...
>>
>> [...]
>>
>> try:
>>    raise value
>> except Case1:
>>    print "did case 1"
>> except (Case2, Case3):
>>    print "did either case 2 or 3"
>> else:
>>    print "did default"
>
> Not bad! Definitely worth considering.

I wrote a simple test that switched between 26 "enums" using three
techniques and measured execution times (2,600,000 switching
operations). I also measured the time with no switching and subtracted
that time from the test times.

Results of the competition (performed with python3.2.3):

1. DICT DISPATCH TABLE (0.2 ?s/switch)

2. IF-ELSE CHAIN (850% slower than DICT DISPATCH TABLE)

3. TRY-EXCEPT (3500% slower than DICT DISPATCH TABLE)


Marko


From roy at panix.com  Sun Mar  2 10:34:33 2014
From: roy at panix.com (Roy Smith)
Date: Sun, 02 Mar 2014 10:34:33 -0500
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7465.1393585687.18130.python-list@python.org>
 <87y50vwjq4.fsf@elektro.pacujo.net>
 <mailman.7468.1393595250.18130.python-list@python.org>
 <87d2i7wbxs.fsf@elektro.pacujo.net>
 <roy-590D18.09433028022014@news.panix.com>
 <87bnxp58t7.fsf@elektro.pacujo.net> <87fvn08vux.fsf@elektro.pacujo.net>
Message-ID: <roy-772D63.10343302032014@news.panix.com>

In article <87fvn08vux.fsf at elektro.pacujo.net>,
 Marko Rauhamaa <marko at pacujo.net> wrote:

> Marko Rauhamaa <marko at pacujo.net>:
> 
> > Roy Smith <roy at panix.com>:
> >
> >> Python already has a switch statement.  It's just spelled funny...
> >>
> >> [...]
> >>
> >> try:
> >>    raise value
> >> except Case1:
> >>    print "did case 1"
> >> except (Case2, Case3):
> >>    print "did either case 2 or 3"
> >> else:
> >>    print "did default"
> >
> > Not bad! Definitely worth considering.
> 
> [...]
> 3. TRY-EXCEPT (3500% slower than DICT DISPATCH TABLE)

I'm glad to hear that.  I hope nobody took me seriously when I suggested 
this.


From marko at pacujo.net  Sun Mar  2 10:52:07 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 02 Mar 2014 17:52:07 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7465.1393585687.18130.python-list@python.org>
 <87y50vwjq4.fsf@elektro.pacujo.net>
 <mailman.7468.1393595250.18130.python-list@python.org>
 <87d2i7wbxs.fsf@elektro.pacujo.net>
 <roy-590D18.09433028022014@news.panix.com>
 <87bnxp58t7.fsf@elektro.pacujo.net>
 <87fvn08vux.fsf@elektro.pacujo.net>
 <roy-772D63.10343302032014@news.panix.com>
Message-ID: <87a9d88uoo.fsf@elektro.pacujo.net>

Roy Smith <roy at panix.com>:

> In article <87fvn08vux.fsf at elektro.pacujo.net>,
>  Marko Rauhamaa <marko at pacujo.net> wrote:
>> 3. TRY-EXCEPT (3500% slower than DICT DISPATCH TABLE)
>
> I'm glad to hear that. I hope nobody took me seriously when I
> suggested this.

I actually have employed the idea before in a related but slightly
different use case.

Anyway, it's extremely close to the switch statement's use case and
should give some guidance if a proper switch statement is ever worked
into the language. What's killing the performance is the backtrace
generation and longjmp trickery. If an analogous syntax could be (A)
separated from BaseException and (B) compiled into a dict, we could have
a winner.


Marko


From rmorgan466 at gmail.com  Sun Mar  2 10:56:56 2014
From: rmorgan466 at gmail.com (Rita)
Date: Sun, 2 Mar 2014 10:56:56 -0500
Subject: source code control and documentation
Message-ID: <CAOF-KfjnM=BXRRnendFsY3iigPyW8PcCTEijQvfcU_9fGwWOXA@mail.gmail.com>

Hi,


I am trying to achieve this, every time I commit to svn I automatically
 run hooks to test my libraries, ATM I am doing this manually

cd libs
PYTHONPATH=. python test_lib.py

and if everything passes I do a svn commit -m 'committing code'

I don't have access to my svn server so I can't create my own hooks (or can
I?)

Also, I would like to auto-document my library and project so, when I do a
svn commit I would like to generate a sphinix-doc (and I am open to
suggestions).  In the source code do I need to do anything special to my
Classes and Functions?

class myClass(object):
  ""do I need to do anything special here"""?

Ideally, I would like to automatically draw a UML diagram since my codebase
is rather large.




How do people achieve this?



-- 
--- Get your facts first, then you can distort them as you please.--
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From rosuav at gmail.com  Sun Mar  2 11:02:32 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 03:02:32 +1100
Subject: source code control and documentation
In-Reply-To: <CAOF-KfjnM=BXRRnendFsY3iigPyW8PcCTEijQvfcU_9fGwWOXA@mail.gmail.com>
References: <CAOF-KfjnM=BXRRnendFsY3iigPyW8PcCTEijQvfcU_9fGwWOXA@mail.gmail.com>
Message-ID: <CAPTjJmp9ZRRrhXs=e1qJLN+ZqxB4yuwkMiroVKmaOfKmk7SuEQ@mail.gmail.com>

On Mon, Mar 3, 2014 at 2:56 AM, Rita <rmorgan466 at gmail.com> wrote:
> I am trying to achieve this, every time I commit to svn I automatically  run
> hooks to test my libraries, ATM I am doing this manually
>
> cd libs
> PYTHONPATH=. python test_lib.py
>
> and if everything passes I do a svn commit -m 'committing code'
>
> I don't have access to my svn server so I can't create my own hooks (or can
> I?)

This is really a subversion question, not a Python one. But this much
I'll say: svn is vastly inferior to modern version control systems
like git and Mercurial (the latter being written in Python and used
for CPython and many other Python-related projects). You can easily
import your svn history into either git or Mercurial (at least, I'm
pretty sure Mercurial offers good import facilities - if not, there
are ways around the problem), so you won't lose anything by switching.
And hook support is excellent.

Personally, I'm very friendly with git - we work together really well.
Mercurial and I are like business acquaintances that don't see each
other quite as often, and interactions are a bit more formal and
stilted. But I know that either one will serve you well, and far more
easily than svn does.

ChrisA


From rosuav at gmail.com  Sun Mar  2 11:23:10 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 03:23:10 +1100
Subject: Can global variable be passed into Python function?
In-Reply-To: <87a9d88uoo.fsf@elektro.pacujo.net>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <bd36a46b-d704-4eb1-9b7d-1308d1fb6699@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7465.1393585687.18130.python-list@python.org>
 <87y50vwjq4.fsf@elektro.pacujo.net>
 <mailman.7468.1393595250.18130.python-list@python.org>
 <87d2i7wbxs.fsf@elektro.pacujo.net>
 <roy-590D18.09433028022014@news.panix.com>
 <87bnxp58t7.fsf@elektro.pacujo.net>
 <87fvn08vux.fsf@elektro.pacujo.net>
 <roy-772D63.10343302032014@news.panix.com>
 <87a9d88uoo.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmqZiuioZ3KmTw6jH-AspsPKnRdE1zR8-rX4WPFWwGqZtw@mail.gmail.com>

On Mon, Mar 3, 2014 at 2:52 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Roy Smith <roy at panix.com>:
>
>> In article <87fvn08vux.fsf at elektro.pacujo.net>,
>>  Marko Rauhamaa <marko at pacujo.net> wrote:
>>> 3. TRY-EXCEPT (3500% slower than DICT DISPATCH TABLE)
>>
>> I'm glad to hear that. I hope nobody took me seriously when I
>> suggested this.
>
> I actually have employed the idea before in a related but slightly
> different use case.
>
> Anyway, it's extremely close to the switch statement's use case and
> should give some guidance if a proper switch statement is ever worked
> into the language. What's killing the performance is the backtrace
> generation and longjmp trickery. If an analogous syntax could be (A)
> separated from BaseException and (B) compiled into a dict, we could have
> a winner.

The trouble is, try/except fundamentally can't be compiled into a
dict, because Python's exception handling is based on subclasses.

try: func()
except FileNotFoundError: pass
except OSError: raise RuntimeError("Oops")
except Exception as e: log(e)
except: log("Aborting!"); raise
finally: log("Done")

How would you handle that with a dict? It's inherently ordered - a
FileNotFoundError would be caught by any one of those clauses, and
since there's no sane way to "pick the narrowest", the best way to
handle it is sequential evaluation. (Also, it's worth noting that
exception lists are not constants. It's possible to do downright
insane things like calling a function to figure out what exceptions to
handle. Yeah, that's pretty stupid, right there.)

A switch block that works with constants and equality *can* be turned
into a dict. If the constants are hashable, use them as the keys
directly; if they're not hashable and/or you want to use object
identity as the criterion (effectively like using 'is' rather than
'==' for your case statements), use id(x) as the keys, and make sure
you have other references to the objects. Then it'll be fine as a
straight-up dict.

If the switch block uses inequalities, then it suffers from the same
problem as the try/except block - it's inherently ordered, in case
(pun intended) there's a switched-on value that matches more than one.
(You could possibly optimize the int case, but that would be way WAY
too specific for a generic language structure.)

ChrisA


From scigenium at gmail.com  Sun Mar  2 11:24:38 2014
From: scigenium at gmail.com (scigenium at gmail.com)
Date: Sun, 2 Mar 2014 08:24:38 -0800 (PST)
Subject: Job - Senior Python Engineer - User Interface Applications,
 Cambridge MA
Message-ID: <a565729b-63bc-463e-a727-b9ae92f805a8@googlegroups.com>

Senior Python Engineer - User Interface Applications
Location : Cambridge MA
Who We Are: 

Gen9 is transforming synthetic biology by creating novel technologies to increase innovation within several industries including biopharmaceuticals, fine chemicals and bio-fuels.  

Currently such genes are synthesized 'one at a time' resulting in high-cost low-capacity gene synthesis capabilities in the marketplace. Gen9 is building the first 'fab' for synthetic biology -- the BioFab(R) platform -- based on next generation gene synthesis technologies.  The BioFab(R) platform was chosen by "The Scientist" as the #1 innovation of 2012. 

Position summary:

Gen9 is looking for a senior software engineer to contribute to software architecture that will help to scale our next-generation DNA synthesis platform.  The ideal candidate will be comfortable with a range of responsibilities as a member of a small, efficient team.  

Responsibilities:

*	Design and develop user-friendly web-based applications to improve work flow management, support scale up of production processes, and query information for data mining and analysis to better enable all aspects of our business
*	Support infrastructure and provide code base maintenance (documentation, testing, and revision control)
*	Respond to R&D and Manufacturing requests for custom requirements on an as needed basis

Requirements:

*	BS/ MS in computer science, bioinformatics, or related degree plus 5-7 years of industry experience, or equivalent combination of education and experience
*	3+ years of experience using and developing within UNIX/Linux environments
*	Demonstrated proficiency with Python, JavaScript, and CSS
*	Demonstrated experience with SQL and database modeling
*	Demonstrated ability to work effectively and with minimal supervision in a small collaborative team
*	Demonstrated ability to multi-task and manage numerous activities simultaneously
*	Strong communication, documentation, and presentation skills
*	Familiarity with biology is not required, but is beneficial

HOW TO APPLY:
Send resume & cover letter to: resumes at gen9bio.com.
Please briefly describe your skills, knowledge, and experience with the Required Qualifications in your cover letter/email.


From invalid at invalid.invalid  Sun Mar  2 11:45:28 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Sun, 2 Mar 2014 16:45:28 +0000 (UTC)
Subject: [OT] Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com>
 <mailman.7560.1393732703.18130.python-list@python.org>
Message-ID: <levn78$mkq$1@reader1.panix.com>

On 2014-03-02, Dave Angel <davea at davea.name> wrote:
>  Grant Edwards <invalid at invalid.invalid> Wrote in message:
>> On 2014-02-24, Michael Torrie <torriem at gmail.com> wrote:
>>
>>>
>>> Why would you think that? The address of the start of your malloc'ed
>>> structure is the same as the address of the first element.  Surely
>>> this is logical?
>> 
>> Not only is it logical, the C standard explicitly requires it.  Here's
>> a second-hand citation since I don't happend to have an actual copy of
>> the standard on hand:
>> 
>>     C1x ???6.7.2.1.13:
>> 
>>        A pointer to a structure object, suitably converted, points to
>>        its initial member ... and vice versa. There may be unnamed
>>        padding within a structure object, but not at its beginning.
>
> The quote you make from the C standard doesn't mention malloc,  so
> you're arguing different things.

No, I'm not.  A pointer to a structure object and a pointer to it's
first field are the same.  It doesn't matter where the object came
from.

> It's not the compiler that casts the malloc return value to the
> struct type.

That's irrelevent.  The actual location of the memory containing the
struct object (static, stack, heap, shared) doesn't matter.  The
address of the first field in a struture object _is_ the address of
the structure object.

-- 
Grant


From breamoreboy at yahoo.co.uk  Sun Mar  2 11:53:06 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 02 Mar 2014 16:53:06 +0000
Subject: Can global variable be passed into Python function?
In-Reply-To: <CAPTjJmqZiuioZ3KmTw6jH-AspsPKnRdE1zR8-rX4WPFWwGqZtw@mail.gmail.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7435.1393523704.18130.python-list@python.org>
 <5f4f5a5f-327a-4616-8235-17ee9e74c488@googlegroups.com>
 <530fef58$0$11113$c3e8da3@news.astraweb.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7465.1393585687.18130.python-list@python.org>
 <87y50vwjq4.fsf@elektro.pacujo.net>
 <mailman.7468.1393595250.18130.python-list@python.org>
 <87d2i7wbxs.fsf@elektro.pacujo.net>
 <roy-590D18.09433028022014@news.panix.com>
 <87bnxp58t7.fsf@elektro.pacujo.net> <87fvn08vux.fsf@elektro.pacujo.net>
 <roy-772D63.10343302032014@news.panix.com>
 <87a9d88uoo.fsf@elektro.pacujo.net>
 <CAPTjJmqZiuioZ3KmTw6jH-AspsPKnRdE1zR8-rX4WPFWwGqZtw@mail.gmail.com>
Message-ID: <levnl9$hjk$1@ger.gmane.org>

On 02/03/2014 16:23, Chris Angelico wrote:
>
> A switch block that works with constants and equality *can* be turned
> into a dict. If the constants are hashable, use them as the keys
> directly; if they're not hashable and/or you want to use object
> identity as the criterion (effectively like using 'is' rather than
> '==' for your case statements), use id(x) as the keys, and make sure
> you have other references to the objects. Then it'll be fine as a
> straight-up dict.
>
> If the switch block uses inequalities, then it suffers from the same
> problem as the try/except block - it's inherently ordered, in case
> (pun intended) there's a switched-on value that matches more than one.
> (You could possibly optimize the int case, but that would be way WAY
> too specific for a generic language structure.)
>
> ChrisA
>

You clearly don't get my point.  I *DON'T* want to use stupid constants 
and stupid equalities, I want to use identities.  I *DON'T* want to use 
stupid ==, I want to use 'is'.  I *DON'T* care how many people with 
years of experience of Python tell me that this is the wrong thing to 
do, that is how I am going to do it.  So, for the final time of asking, 
how do I do the above with, and only with, the identity, even if you 
stupidly keep on trying to tell me that this is wrong?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From breamoreboy at yahoo.co.uk  Sun Mar  2 11:55:49 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 02 Mar 2014 16:55:49 +0000
Subject: [OT] Can global variable be passed into Python function?
In-Reply-To: <levn78$mkq$1@reader1.panix.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com>
 <mailman.7560.1393732703.18130.python-list@python.org>
 <levn78$mkq$1@reader1.panix.com>
Message-ID: <levnqa$hjk$2@ger.gmane.org>

On 02/03/2014 16:45, Grant Edwards wrote:
>
> That's irrelevent.  The actual location of the memory containing the
> struct object (static, stack, heap, shared) doesn't matter.  The
> address of the first field in a struture object _is_ the address of
> the structure object.
>

You say struture, I'll say structure, let's call the whole thing off :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From torriem at gmail.com  Sun Mar  2 13:48:15 2014
From: torriem at gmail.com (Michael Torrie)
Date: Sun, 02 Mar 2014 11:48:15 -0700
Subject: Can global variable be passed into Python function?
In-Reply-To: <CAPTjJmpmw=ejJfwHOGWszDi0G7epn6wXK6ZEgtX52xWHQHtp4Q@mail.gmail.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
 <CAPTjJmpmw=ejJfwHOGWszDi0G7epn6wXK6ZEgtX52xWHQHtp4Q@mail.gmail.com>
Message-ID: <53137CEF.6070205@gmail.com>

On 03/02/2014 03:07 AM, Chris Angelico wrote:
> 
>>>> import os
>>>> type(os.POSIX_FADV_RANDOM)
> <class 'int'>
> 
> So use ==. If it's later changed and you have to instead use 'is', you
> can change your code.

I don't see why == wouldn't continue to work if os.POSIX_FADV_RANDOM
became an object of a different type.



From nicholas.cole at gmail.com  Sun Mar  2 14:08:42 2014
From: nicholas.cole at gmail.com (Nicholas Cole)
Date: Sun, 2 Mar 2014 19:08:42 +0000
Subject: why indentation should be part of the syntax
In-Reply-To: <roy-3F8596.09385002032014@news.panix.com>
References: <mailman.7568.1393756930.18130.python-list@python.org>
 <roy-3F8596.09385002032014@news.panix.com>
Message-ID: <CAAu18hfu9_vNE-P4dRDSqnJTZ_eV8PfupZfTtRSK_KGLdbSo=g@mail.gmail.com>

On Sun, Mar 2, 2014 at 2:38 PM, Roy Smith <roy at panix.com> wrote:
> In article <mailman.7568.1393756930.18130.python-list at python.org>,
>  Stefan Behnel <stefan_ml at behnel.de> wrote:
>
>> Haven't seen any mention of it on this list yet, but since it's such an
>> obvious flaw in quite a number of programming languages, here's a good
>> article on the recent security bug in iOS, which was due to accidentally
>> duplicated code not actually being as indented as it looked:
>>
>> https://www.imperialviolet.org/2014/02/22/applebug.html
>>
>> Stefan
>
> Hogwash.  What this looks like is two gotos in a row.  Anybody who
> reviewed this code would have thrown up a red flag when they saw two
> gotos in a row.  If anything, the "incorrect" indentation makes it even
> more obvious.  Any static code analyzer would have also caught this as
> an unreachable statement.
>
> Paraphrasing this into Python, you get:
>
> def bogus():
>     if SSLHashSHA1.update(hashCtx, serverRandom) != 0:
>         raise fail
>     if SSLHashSHA1.update(hashCtx, signedParams) != 0:
>         raise fail
>         raise fail
>     if SSLHashSHA1.final(hashCtx, hashOut) != 0:
>         raise fail
>
> which is syntactically valid (at least, I can import it), but clearly
> not what the author intended.  So how did Python's indentation rules
> save us?

Actually, that's incorrect.  The bug (written in Python) would have been:

if SSLHashSHA1.update(hashCtx, signedParams) != 0:
    raise fail
raise fail # ie. no indent.

If written with the indent, it's a useless line of code, but it
doesn't become a bug.


From davea at davea.name  Sun Mar  2 14:17:41 2014
From: davea at davea.name (Dave Angel)
Date: Sun, 2 Mar 2014 14:17:41 -0500 (EST)
Subject: [OT] Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com> <leua81$fjj$1@ger.gmane.org>
 <CAPTjJmpeLq_7R=Z5J14dpny6XJ0xx-8CnueMJ02pcnDsULZTdg@mail.gmail.com>
 <levb36$jmk$1@ger.gmane.org>
 <CAPTjJmrCXrqZzCrvWm7Bb0yG3wDge=kheLL4w83W79MQ4XKGdg@mail.gmail.com>
Message-ID: <levvs9$6o2$1@ger.gmane.org>

 Chris Angelico <rosuav at gmail.com> Wrote in message:
> On Mon, Mar 3, 2014 at 12:22 AM, Dave Angel <davea at davea.name> wrote:
>> Sure,  for some definition of "usable".  Overhead such as block
>>  size, freelist pointer etc., are obviously outside of the
>>  returned block.  But the array size that's specified in a call to
>>  new [], and the vptr, are definitely inside the malloc'ed block,
>>  and may be before the struct data.
> 
> Hmm. Last I was working with it, the array size to new[] was outside
> the block, just as the block size to malloc(). The vptr is part of any
> struct/class with virtual functions, and effectively acts as a hidden
> class member, so you get one of those inside the block, and it's
> included in sizeof.
> 
> //Allocated Space: The Final Frontier!
> #include <stdio.h> //cout sucks :)
> 
> class Foo
> {
>     int x;
>     int y;
>     int z;
> };
> 
> class Bar
> {
>     int x;
>     int y;
>     int z;
>     virtual int get_x() {return x;}
> };
> 
> int main()
> {
>     printf("sizeof(int) = %u\n",sizeof(int));
>     printf("sizeof(int*) = %u\n",sizeof(int*));
>     printf("sizeof(Foo) = %u\n",sizeof(Foo));
>     printf("sizeof(Bar) = %u\n",sizeof(Bar));
>     Foo *foo = new Foo[10];
>     printf("foo = %p/%p = %u\n",foo,foo+10,(char *)(foo+10)-(char *)foo);
>     Bar *bar = new Bar[10];
>     printf("bar = %p/%p = %u\n",bar,bar+10,(char *)(bar+10)-(char *)bar);
>     return 0;
> }
> 
> 
> rosuav at sikorsky:~$ g++ frontier.cpp && ./a.out
> sizeof(int) = 4
> sizeof(int*) = 8
> sizeof(Foo) = 12
> sizeof(Bar) = 24
> foo = 0xf38010/0xf38088 = 120
> bar = 0xf38090/0xf38180 = 240
> 
> 
> 
> The rules of structs are that they be contiguous, that they be laid
> out sequentially, and that any padding needed between structures is at
> the end of the previous one (which is why three of 4 bytes makes 12
> bytes, but three of 4 bytes plus 8 bytes makes 24 - the eight-byte
> pointer has to be aligned on a multiple of eight bytes, so having a
> 20-byte structure that starts with an 8-byte pointer is a no-no). The
> allocated block of memory is, by definition, the same as the pointer
> to its first element. As it happens, the pointer bar is not synonymous
> with &bar->x, &bar->y, or &bar->z, which means the vptr is at the
> beginning of bar, which makes sense; but the compiler's not obliged to
> do that, and in some cases may choose not to - for instance, if bar
> (with a virtual function) inherited from foo (with none), it might be
> convenient to allow a pointer-cast to not change the value of the
> pointer. (g++ 4.7.2 still puts the vptr at the beginning of bar in
> that case, but other compilers or other versions may differ.)
> 
> Array size is outside the block, presumably before it, as &foo[0] is
> by definition identical to foo, and there's no room inside the
> structure for any spare data. Virtual function table is inside the
> block because it's a hidden member of the object (like __class__ in
> Python, only better hidden).
> 

Array size is inside the malloc block, but outside the struct
 block.  As you can see if you try to delete without the brackets
 when you used new [], some runtimes will crash. 

This is not to say that there will always be these extra offsets, 
 just that they can be there.

-- 
DaveA



From rosuav at gmail.com  Sun Mar  2 14:24:16 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 06:24:16 +1100
Subject: [OT] Can global variable be passed into Python function?
In-Reply-To: <levnqa$hjk$2@ger.gmane.org>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com>
 <mailman.7560.1393732703.18130.python-list@python.org>
 <levn78$mkq$1@reader1.panix.com> <levnqa$hjk$2@ger.gmane.org>
Message-ID: <CAPTjJmq5gEanX6fWq_yCU9K9PLsf7n1CqrDAMS9YZV=6P4czZw@mail.gmail.com>

On Mon, Mar 3, 2014 at 3:55 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> On 02/03/2014 16:45, Grant Edwards wrote:
>>
>>
>> That's irrelevent.  The actual location of the memory containing the
>> struct object (static, stack, heap, shared) doesn't matter.  The
>> address of the first field in a struture object _is_ the address of
>> the structure object.
>>
>
> You say struture, I'll say structure, let's call the whole thing off :)

:)

Note that, technically, Grant is correct as long as you grant (heh)
that a structure may have an invisible member, the virtual function
table pointer. C++ only (I don't believe C has virtual functions - but
it may have grown them in one of the newer standards), so in C, all
members are public.

With an array, the array's pointer *is* the same as the pointer to its
first member, because adding zero to a pointer does nothing, and x <->
&x[0] <-> &(*(x+0)).

ChrisA


From christian at python.org  Sun Mar  2 14:25:24 2014
From: christian at python.org (Christian Heimes)
Date: Sun, 02 Mar 2014 20:25:24 +0100
Subject: Password validation security issue
In-Reply-To: <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
Message-ID: <lf00im$dbm$1@ger.gmane.org>

On 01.03.2014 21:11, Chris Angelico wrote:
> The problem isn't SHA-256. The problem is insecure passwords, the way
> we've been taught to make them by the banks. Hence, XKCD 936.

Your argumentation is just wrong. You are saying "It's OK to use a
totally insecure way to hash passwords because passwords are insecure".
The point of KDF and KSA is to derive some token from a low entropy
source (human input) that makes an attack harder. Please do your reading
and trust secure experts on algorithms like PBKDF2, bcrypt and
scrypt. hash(salt + password) is outdated and proven to be insecure for
at least a decade, more like 15+ years.

The concept of passwords itself is insecure. But we are stuck with
passwords for authentication mechanism for the foreseeable future. 2FA
is an attempt to increase the security of passwords-based authentication
schemes.

Christian



From rosuav at gmail.com  Sun Mar  2 14:32:28 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 06:32:28 +1100
Subject: [OT] Can global variable be passed into Python function?
In-Reply-To: <levvs9$6o2$1@ger.gmane.org>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com> <leua81$fjj$1@ger.gmane.org>
 <CAPTjJmpeLq_7R=Z5J14dpny6XJ0xx-8CnueMJ02pcnDsULZTdg@mail.gmail.com>
 <levb36$jmk$1@ger.gmane.org>
 <CAPTjJmrCXrqZzCrvWm7Bb0yG3wDge=kheLL4w83W79MQ4XKGdg@mail.gmail.com>
 <levvs9$6o2$1@ger.gmane.org>
Message-ID: <CAPTjJmqyZ53ON_PrR8-afzMYNLA=6Fbj2t=H6ydxAYSqFE2wOg@mail.gmail.com>

On Mon, Mar 3, 2014 at 6:17 AM, Dave Angel <davea at davea.name> wrote:
> Array size is inside the malloc block, but outside the struct
>  block.  As you can see if you try to delete without the brackets
>  when you used new [], some runtimes will crash.

As in, you have to use "delete [] x" to correspond with "x = new
whatever[n]"? Yes, that's right, but that array size is earlier in
memory than x itself. I can pretend that x is the same as one declared
statically as "whatever x[n]", and it'll function the same way. When
new[] is implemented using malloc(), it'll be something like this:

{
    data = malloc(n * sizeof(whatever) + sizeof n);
    *(int *)data = n;
    return ((int *)data)+1;
}

so in that case, the array size is inside the malloc'd block, but it's
still invisible to the calling function. A fully compliant C++
implementation could choose to store that elsewhere, in some kind of
lookup table - it could then easily catch bugs like "delete
malloc(1)", "delete [] malloc(1)", "delete [] new whatever", and
"delete new whatever[1]" (because the pointer given wouldn't be in the
'new' table or the 'new[]' table, respectively).

ChrisA


From as at sci.fi  Sun Mar  2 14:40:46 2014
From: as at sci.fi (Anssi Saari)
Date: Sun, 02 Mar 2014 21:40:46 +0200
Subject: passing an option to the python interpreter
References: <mailman.7026.1392503602.18130.python-list@python.org>
 <871tz4kn6p.fsf@elektro.pacujo.net>
Message-ID: <vg3a9d8wfr5.fsf@coffee.modeemi.fi>

Marko Rauhamaa <marko at pacujo.net> writes:

> Jabba Laci <jabba.laci at gmail.com>:
>
>> I tried this:
>>
>> #!/usr/bin/env python -u
>
> The hash-bang notation is quite rigid; it only accepts a single argument
> ("python") to the command ("/usr/bin/env").
>
> I don't know if there is a simple workaround.

Using the relevant environment variable (PYTHONUNBUFFERED) seems simple
to me.


From roy at panix.com  Sun Mar  2 15:01:09 2014
From: roy at panix.com (Roy Smith)
Date: Sun, 02 Mar 2014 15:01:09 -0500
Subject: Password validation security issue
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
Message-ID: <roy-5B94F1.15010902032014@news.panix.com>

In article <mailman.7592.1393788339.18130.python-list at python.org>,
 Christian Heimes <christian at python.org> wrote:

> On 01.03.2014 21:11, Chris Angelico wrote:
> > The problem isn't SHA-256. The problem is insecure passwords, the way
> > we've been taught to make them by the banks. Hence, XKCD 936.
> 
> Your argumentation is just wrong. You are saying "It's OK to use a
> totally insecure way to hash passwords because passwords are insecure".
> The point of KDF and KSA is to derive some token from a low entropy
> source (human input) that makes an attack harder. Please do your reading
> and trust secure experts on algorithms like PBKDF2, bcrypt and
> scrypt. hash(salt + password) is outdated and proven to be insecure for
> at least a decade, more like 15+ years.
> 
> The concept of passwords itself is insecure. But we are stuck with
> passwords for authentication mechanism for the foreseeable future. 2FA
> is an attempt to increase the security of passwords-based authentication
> schemes.
> 
> Christian

Security is as much about cryptography as it is about human factors and 
business drivers.  You can make things resistant to brute-force attacks 
by using longer keys, but people are still going to pick bad passwords.  
You can force them to pick "good" passwords by rejecting their first 37 
choices, but all that does is encourage them to write the passwords down 
on sticky notes.

And, yes, you can make things more secure with 2FA, but there's a cost 
there.  You have to purchase and manage the infrastructure.  More than 
that, there's lost business if potential customers prefer a competitor's 
product because it's easier to access.  Many of the known insecure 
systems we use today are not that way because the people who run them 
are stupid; they're that way because the people who run them have worked 
the numbers and decided the cost to implement more secure systems would 
exceed the risk exposure.

We recently got a frothing email from a user, which basically said, "You 
farking idiots, you emailed me my password in plain text!"  It turns 
out, his user name was the same as his password and what we had sent him 
(in response to an account recovery query) was his username.  In 
response to that, we altered our account generation process to forbid 
passwords which are too similar to your chosen username or email 
address.  Which, of course, means we've taken one more step down the 
road to forcing our users to write their passwords on sticky notes.


From rosuav at gmail.com  Sun Mar  2 15:32:16 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 07:32:16 +1100
Subject: Password validation security issue
In-Reply-To: <roy-5B94F1.15010902032014@news.panix.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
Message-ID: <CAPTjJmpkpHU2Gi2xhaOueJBkrqHOiDCBY0DTLZTRcAKUWK9GdQ@mail.gmail.com>

On Mon, Mar 3, 2014 at 7:01 AM, Roy Smith <roy at panix.com> wrote:
> We recently got a frothing email from a user, which basically said, "You
> farking idiots, you emailed me my password in plain text!"  It turns
> out, his user name was the same as his password and what we had sent him
> (in response to an account recovery query) was his username.

Sadly, there *are* systems that will actually email passwords in plain
text, and don't tell you so beforehand (Mailman at least tells you
that the password isn't meant for security). I met one recently. Did
not appreciate that. Fortunately when I changed my password, the new
password wasn't emailed back to me.

ChrisA


From marko at pacujo.net  Sun Mar  2 16:03:30 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 02 Mar 2014 23:03:30 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
 <CAPTjJmpmw=ejJfwHOGWszDi0G7epn6wXK6ZEgtX52xWHQHtp4Q@mail.gmail.com>
 <mailman.7588.1393786109.18130.python-list@python.org>
Message-ID: <87txbg48kd.fsf@elektro.pacujo.net>

Michael Torrie <torriem at gmail.com>:

> I don't see why == wouldn't continue to work if os.POSIX_FADV_RANDOM
> became an object of a different type.

It probably would.

If one were begging for trouble, one *could* define:

   class ABC:
       A = 1
       B = 1.0
       C = 1+0j

Now:

   ABC.A == ABC.B
   ABC.B == ABC.C
   ABC.C == ABC.A

but:

   ABC.A is not ABC.B
   ABC.B is not ABC.C
   ABC.C is not ABC.A


Marko


From roy at panix.com  Sun Mar  2 16:16:14 2014
From: roy at panix.com (Roy Smith)
Date: Sun, 02 Mar 2014 16:16:14 -0500
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
 <CAPTjJmpmw=ejJfwHOGWszDi0G7epn6wXK6ZEgtX52xWHQHtp4Q@mail.gmail.com>
 <mailman.7588.1393786109.18130.python-list@python.org>
 <87txbg48kd.fsf@elektro.pacujo.net>
Message-ID: <roy-E6687F.16161402032014@news.panix.com>

In article <87txbg48kd.fsf at elektro.pacujo.net>,
 Marko Rauhamaa <marko at pacujo.net> wrote:

> Michael Torrie <torriem at gmail.com>:
> 
> > I don't see why == wouldn't continue to work if os.POSIX_FADV_RANDOM
> > became an object of a different type.
> 
> It probably would.
> 
> If one were begging for trouble, one *could* define:
> 
>    class ABC:
>        A = 1
>        B = 1.0
>        C = 1+0j
> 
> Now:
> 
>    ABC.A == ABC.B
>    ABC.B == ABC.C
>    ABC.C == ABC.A
> 
> but:
> 
>    ABC.A is not ABC.B
>    ABC.B is not ABC.C
>    ABC.C is not ABC.A
> 
> 
> Marko

On can do all sorts of bizarre things.  If you wish to shoot yourself in 
the foot, Python is happy to provide the gun.

class ABC(object):
    _instance = None
    def __new__(cls):
        if cls._instance is None:
            i = object.__new__(cls)
            i.__class__ = ABC
            cls._instance = i
        return cls._instance

    def __eq__(self, other):
        return False

a = ABC()
b = ABC()

print a is b
print a == b


From rosuav at gmail.com  Sun Mar  2 16:28:17 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 08:28:17 +1100
Subject: Can global variable be passed into Python function?
In-Reply-To: <87txbg48kd.fsf@elektro.pacujo.net>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
 <CAPTjJmpmw=ejJfwHOGWszDi0G7epn6wXK6ZEgtX52xWHQHtp4Q@mail.gmail.com>
 <mailman.7588.1393786109.18130.python-list@python.org>
 <87txbg48kd.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpQtOOeohCsFQPZGEq8x4M1cdJ6=29nFw2gyDte+yR2Kg@mail.gmail.com>

On Mon, Mar 3, 2014 at 8:03 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> If one were begging for trouble, one *could* define:
>
>    class ABC:
>        A = 1
>        B = 1.0
>        C = 1+0j

You're missing the point of flags, though. One does not use floats for
flags. Flags are normally going to be integers (passed directly to an
underlying C API), strings (self-documenting), or arbitrary objects
with no value beyond their identities. In all cases, value equality is
the normal way to recognize them, except in the special case of
bit-flag integers, where you use bitwise operations (and then equality
checks, possibly):

DIRECTORY = 512 # Not sure that one's right, tbh
OWNER_READ = 256
OWNER_WRITE = 128
OWNER_EXEC = 64
GROUP_READ = 32
...
OTHERS_EXEC = 1

mode = 1005
if mode & DIRECTORY:
    # It's a directory!
if mode & OTHERS_READ:
    # You're allowed to read (eg 'ls')
if mode & GROUP_EXEC:
    # You get the idea.

With multi-bit flags you might have to do a bitwise AND followed by an
equality check:

NOT_STICKY = 0
STICKY_PARTIAL = 16
STICKY_MOSTLY = 32
STICKY_ENTIRELY = 48
STICKY_BITS = 48

if style & STICKY_BITS == STICKY_MOSTLY:
    # I've no idea what this means, actually

At no time can you do identity checks. It might happen to work with
the lower bit values and CPython, but when you check the 2048 bit, you
don't get that. Value is all that matters.

ChrisA


From yoavglazner at gmail.com  Sun Mar  2 16:30:03 2014
From: yoavglazner at gmail.com (Glazner)
Date: Sun, 2 Mar 2014 13:30:03 -0800 (PST)
Subject: Boxes of O's
In-Reply-To: <729104f4-92f8-48a3-9b7c-e7ba4fb6a38e@googlegroups.com>
References: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>
 <mailman.7529.1393701408.18130.python-list@python.org>
 <31bde8f6-25a6-484f-af6b-bbef7f7a0fdf@googlegroups.com>
 <mailman.7532.1393703673.18130.python-list@python.org>
 <729104f4-92f8-48a3-9b7c-e7ba4fb6a38e@googlegroups.com>
Message-ID: <86560890-42bb-4090-a178-1669d4486dcf@googlegroups.com>

On Sunday, March 2, 2014 4:43:48 PM UTC+2, geni... at gmail.com wrote:
> I agree with you and really appreciate your experience. But what I was looking for is clues. Thank you anyway

#not tested
for i in range(n):
  for j in range(n*2):
    if i in (0, n - 1) or j in (0, n*2 - 1):
      print('o', end='')
    else:
      print(' ', end='')
   print()


From torriem at gmail.com  Sun Mar  2 16:44:08 2014
From: torriem at gmail.com (Michael Torrie)
Date: Sun, 02 Mar 2014 14:44:08 -0700
Subject: Can global variable be passed into Python function?
In-Reply-To: <87txbg48kd.fsf@elektro.pacujo.net>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
 <CAPTjJmpmw=ejJfwHOGWszDi0G7epn6wXK6ZEgtX52xWHQHtp4Q@mail.gmail.com>
 <mailman.7588.1393786109.18130.python-list@python.org>
 <87txbg48kd.fsf@elektro.pacujo.net>
Message-ID: <5313A628.9080501@gmail.com>

On 03/02/2014 02:03 PM, Marko Rauhamaa wrote:
> Michael Torrie <torriem at gmail.com>:
> 
>> I don't see why == wouldn't continue to work if os.POSIX_FADV_RANDOM
>> became an object of a different type.
> 
> It probably would.
> 
> If one were begging for trouble, one *could* define:
> 
>    class ABC:
>        A = 1
>        B = 1.0
>        C = 1+0j

And one could also set A=1 and B=1 if he was trying to be stupid.  That
would fail the equality test and the identity test (in CPython).  Seems
like this argument is getting a bit on the absurd side.  The normal
idiom is to use equality checks to test state variables' *values*.  I
don't know of any developer that would purposely try to break that when
defining a new module or class.

If Mark H wants to use an idiom that isn't conventional, or isn't widely
used, he is free to do so; I can't see much harm in it.  But certainly
it's not the "normal" way that it's done in Python from what I can see.


From torriem at gmail.com  Sun Mar  2 16:48:02 2014
From: torriem at gmail.com (Michael Torrie)
Date: Sun, 02 Mar 2014 14:48:02 -0700
Subject: Boxes of O's
In-Reply-To: <729104f4-92f8-48a3-9b7c-e7ba4fb6a38e@googlegroups.com>
References: <c753ba44-379b-4322-96c0-4ba5cb8fa7c1@googlegroups.com>
 <mailman.7529.1393701408.18130.python-list@python.org>
 <31bde8f6-25a6-484f-af6b-bbef7f7a0fdf@googlegroups.com>
 <mailman.7532.1393703673.18130.python-list@python.org>
 <729104f4-92f8-48a3-9b7c-e7ba4fb6a38e@googlegroups.com>
Message-ID: <5313A712.60507@gmail.com>

On 03/02/2014 07:43 AM, geniusrko at gmail.com wrote:
> I agree with you and really appreciate your experience. But what I
> was looking for is clues. Thank you anyway

Not sure what you mean. Chris certainly offered you clues to solving
this problem.  Certainly he pointed you in the right direction to learn
how to approach a problem and debug code.  Seems like what you really
wanted was the answer to be given you for this homework problem.  And
usually someone is willing to step up and do the work for you, so you
lucked out.



From marko at pacujo.net  Sun Mar  2 17:46:49 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 03 Mar 2014 00:46:49 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
 <CAPTjJmpmw=ejJfwHOGWszDi0G7epn6wXK6ZEgtX52xWHQHtp4Q@mail.gmail.com>
 <mailman.7588.1393786109.18130.python-list@python.org>
 <87txbg48kd.fsf@elektro.pacujo.net>
 <mailman.7596.1393796658.18130.python-list@python.org>
Message-ID: <87lhws43s6.fsf@elektro.pacujo.net>

Michael Torrie <torriem at gmail.com>:

> And one could also set A=1 and B=1 if he was trying to be stupid.
> [...]
> If Mark H wants to use an idiom that isn't conventional, or isn't
> widely used, he is free to do so; I can't see much harm in it. But
> certainly it's not the "normal" way that it's done in Python from what
> I can see.

You might be referring to what I have proposed.

Note that the idiom is in use in some standard python modules
(socket.py, ftplib.py, argparse.py, optparse.py). It is used extensively
in sre_compile.py/sre_constants.py:

   ANY = "any"
   [...]
   AT = "at"
   [...]
   CALL = "call"
   [...]
   IN = "in"

           elif op is IN:
           [...]
           elif op is ANY:
           [...]
           elif op is CALL:
           [...]
           elif op is AT:


Marko


From davea at davea.name  Sun Mar  2 17:58:36 2014
From: davea at davea.name (Dave Angel)
Date: Sun, 2 Mar 2014 17:58:36 -0500 (EST)
Subject: [OT] Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com> <leua81$fjj$1@ger.gmane.org>
 <CAPTjJmpeLq_7R=Z5J14dpny6XJ0xx-8CnueMJ02pcnDsULZTdg@mail.gmail.com>
 <levb36$jmk$1@ger.gmane.org>
 <CAPTjJmrCXrqZzCrvWm7Bb0yG3wDge=kheLL4w83W79MQ4XKGdg@mail.gmail.com>
 <levvs9$6o2$1@ger.gmane.org>
 <CAPTjJmqyZ53ON_PrR8-afzMYNLA=6Fbj2t=H6ydxAYSqFE2wOg@mail.gmail.com>
Message-ID: <lf0cqe$14l$1@ger.gmane.org>

 Chris Angelico <rosuav at gmail.com> Wrote in message:
>
> }
> 
> so in that case, the array size is inside the malloc'd block, but it's
> still invisible to the calling function. 
> 

Please quit using negative language when you're so vehemently
 agreeing with me. 

The data is sometimes not at the beginning of the malloc'ed block.

-- 
DaveA



From rvernucio at gmail.com  Sun Mar  2 18:10:06 2014
From: rvernucio at gmail.com (Renato)
Date: Sun, 2 Mar 2014 15:10:06 -0800 (PST)
Subject: Password validation security issue
In-Reply-To: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
Message-ID: <fe1cbc09-7004-42b4-b1ed-69b8083013eb@googlegroups.com>

I would like to thank every one who posted a reply. I learnt a lot from you, guys! I appreciate your attention and your help :)

I took a class on Computer Simulation last year. It was told that deterministic (pseudo-)random numbers are excellent for simulations, because they allow debugging and replication when using a seed(). But it was said that deterministic random numbers weren't indeed suitable for encryption and security issues in general. For this purpose, non-deterministc stochastic methods would be more indicated. I learnt a lot about deterministic random numbers generation in this course, like using Mersenne Twister algorithm, but I learnt nothing about encryption, since it wasn't in the scope of that course. Could you suggest some introductory material concerning encryption? I have an intermediate math background (calculus, linear algebra etc) and I'm willing to learn more about security matters.

One last thing, about my original question. So, the only way of encapsulating a Python script content is to code a simple binary program to call it?

Regards,
Renato


Em s?bado, 1 de mar?o de 2014 14h49min49s UTC-3, Renato  escreveu:
> Hello everybody, I implemented a password validation with a Python 2.7.5 script in OpenSUSE 13.1. The user calls it passing 'login' and 'password' as arguments. I made a dictionary in the format hashtable = {'login':'password'} and I use this hash table to compare the 'login' and 'password' that were passed in order to validate them. The problem is that any user who can execute the script will be able to read it too (since it must be read by python's interpreter), and this is causing some security issues since any user can access all other users' passwords if he opens this script and reads the code.
> 
> 
> 
> My question is: is there a way of preventing the user from reading the script's content? Is there any strategy I could use to hide the passwords from the users?



From breamoreboy at yahoo.co.uk  Sun Mar  2 18:55:56 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 02 Mar 2014 23:55:56 +0000
Subject: 3.4rc2 and pip on windows
Message-ID: <lf0ge3$fbv$1@ger.gmane.org>

Trying to install pyttsx, it doesn't strike me as very clever that, as 
seen below, you get "Successfully installed pyttsx" despite the syntax 
errors and you can't actually do an import.

c:\Users\Mark\CrossCode>c:\Python34\Scripts\pip3.4.exe install pyttsx
Downloading/unpacking pyttsx
   Downloading pyttsx-1.1.tar.gz
   Running setup.py 
(path:C:\Users\Mark\AppData\Local\Temp\pip_build_Mark\pyttsx\setup.py) 
egg_info for package pyttsx

Installing collected packages: pyttsx
   Running setup.py install for pyttsx
       File "C:\Python34\Lib\site-packages\pyttsx\driver.py", line 105
         except Exception, e:
                         ^
     SyntaxError: invalid syntax

[other syntax errors snipped]

Successfully installed pyttsx
Cleaning up...

c:\Users\Mark\CrossCode>py -3.4
Python 3.4.0rc2 (v3.4.0rc2:a300712ed38c, Feb 23 2014, 10:49:04) [MSC 
v.1600 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
 >>> import pyttsx
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
   File "C:\Python34\lib\site-packages\pyttsx\__init__.py", line 18, in 
<module>
     from engine import Engine

I've looked at pyttsx in my 3.3 site-packages and it appears that I've 
manually run 2to3.  Is this something that could be done automatically 
by pip?  Your thoughts please, ladies and gentlemen.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From musicdenotation at gmail.com  Sun Mar  2 18:14:09 2014
From: musicdenotation at gmail.com (musicdenotation at gmail.com)
Date: Mon, 3 Mar 2014 06:14:09 +0700
Subject: Functional programming
Message-ID: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>

If Python is not a fnctional language, then which programming paradigmis dominant?

From tjreedy at udel.edu  Sun Mar  2 19:07:36 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 02 Mar 2014 19:07:36 -0500
Subject: 3.4rc2 and pip on windows
In-Reply-To: <lf0ge3$fbv$1@ger.gmane.org>
References: <lf0ge3$fbv$1@ger.gmane.org>
Message-ID: <lf0h42$l88$2@ger.gmane.org>

On 3/2/2014 6:55 PM, Mark Lawrence wrote:
> Trying to install pyttsx, it doesn't strike me as very clever that, as
> seen below, you get "Successfully installed pyttsx" despite the syntax
> errors and you can't actually do an import.
>
> c:\Users\Mark\CrossCode>c:\Python34\Scripts\pip3.4.exe install pyttsx
> Downloading/unpacking pyttsx
>    Downloading pyttsx-1.1.tar.gz
>    Running setup.py
> (path:C:\Users\Mark\AppData\Local\Temp\pip_build_Mark\pyttsx\setup.py)
> egg_info for package pyttsx
>
> Installing collected packages: pyttsx
>    Running setup.py install for pyttsx
>        File "C:\Python34\Lib\site-packages\pyttsx\driver.py", line 105
>          except Exception, e:
>                          ^
>      SyntaxError: invalid syntax
>
> [other syntax errors snipped]
>
> Successfully installed pyttsx

A bug it seems to me.

> Cleaning up...
>
> c:\Users\Mark\CrossCode>py -3.4
> Python 3.4.0rc2 (v3.4.0rc2:a300712ed38c, Feb 23 2014, 10:49:04) [MSC
> v.1600 32 bit (Intel)] on win32
> Type "help", "copyright", "credits" or "license" for more information.
>  >>> import pyttsx
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
>    File "C:\Python34\lib\site-packages\pyttsx\__init__.py", line 18, in
> <module>
>      from engine import Engine
>
> I've looked at pyttsx in my 3.3 site-packages and it appears that I've
> manually run 2to3.  Is this something that could be done automatically
> by pip?  Your thoughts please, ladies and gentlemen.

I should hope so.

-- 
Terry Jan Reedy



From ben+python at benfinney.id.au  Sun Mar  2 19:08:42 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 03 Mar 2014 11:08:42 +1100
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
Message-ID: <85mwh8jg8l.fsf@benfinney.id.au>

musicdenotation at gmail.com writes:

> If Python is not a fnctional language, then which programming
> paradigmis dominant?

Python uses a mixture of programming paradigms. Object-oriented,
procedural, functional, and probably some I don't recall.

So it's not accurate to say ?Python is not a functional language?. You
can do functional programming in Python. But you're not required to :-)

-- 
 \          ?It's dangerous to be right when the government is wrong.? |
  `\                                   ?Francois Marie Arouet Voltaire |
_o__)                                                                  |
Ben Finney



From tjreedy at udel.edu  Sun Mar  2 19:05:45 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 02 Mar 2014 19:05:45 -0500
Subject: Functional programming
In-Reply-To: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
Message-ID: <lf0h0j$l88$1@ger.gmane.org>

On 3/2/2014 6:14 PM, musicdenotation at gmail.com wrote:
> If Python is not a fnctional language, then which programming paradigmis dominant?

Python is an object based procedural language with builtin classes and 
many functional features. Arguing about the precise wording of such a 
statement is not worthwhile.

-- 
Terry Jan Reedy



From juraj.ivancic at gmail.com  Sun Mar  2 19:07:27 2014
From: juraj.ivancic at gmail.com (=?ISO-8859-2?Q?Juraj_Ivan=E8i=E6?=)
Date: Mon, 03 Mar 2014 01:07:27 +0100
Subject: how to get bytes from bytearray without copying
Message-ID: <lf0h3g$m7r$1@ger.gmane.org>

Is it possible to somehow 'steal' bytearray's buffer and make it a 
read-only bytes? I failed to find a way to do this, and would like to 
make sure.

My use case is, I would expect, fairly common. I read a certain 
(potentially very large) amount of data from the network into a 
pre-allocated bytearray. From that point on, this data is logically 
read-only. To prevent making redundant copies, I wrap it in a 
memoryview, and then slice and dice it. The problem with this memoryview 
is that it, and its slices, are considered writable, and thus cannot be 
hashed:

ValueError: cannot hash writable memoryview object

The only way (AFAICT) to make this work is to first create a bytes 
object from bytearray, but this copies the data. I don't need this copy, 
so I'd like to avoid it, because of both principle and performance reasons.

Is there any reason why bytearray isn't able to release/convert its 
buffer to bytes? I see that it has a clear() method which... well... 
clears it. The former would be much more useful.

I would also be content if there is some way of making memoryview 
artificially read-only to avoid the above error.

Any help/thoughts/comments are highly appreciated.



From roy at panix.com  Sun Mar  2 19:11:30 2014
From: roy at panix.com (Roy Smith)
Date: Sun, 02 Mar 2014 19:11:30 -0500
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7605.1393805404.18130.python-list@python.org>
Message-ID: <roy-8499B3.19113002032014@news.panix.com>

In article <mailman.7605.1393805404.18130.python-list at python.org>,
 Terry Reedy <tjreedy at udel.edu> wrote:

> On 3/2/2014 6:14 PM, musicdenotation at gmail.com wrote:
> > If Python is not a fnctional language, then which programming paradigmis 
> > dominant?
> 
> Python is an object based procedural language with builtin classes and 
> many functional features. Arguing about the precise wording of such a 
> statement is not worthwhile.

+1 QOTW.  Especially the second sentence.


From miguelcoam at gmail.com  Sun Mar  2 19:38:49 2014
From: miguelcoam at gmail.com (Mike)
Date: Sun, 2 Mar 2014 16:38:49 -0800 (PST)
Subject: Error compressing tar file
Message-ID: <d9194b4f-f356-4597-8217-9ae43f586e4b@googlegroups.com>

Hello,
I have the script that make a backup file (this process is ok), but now i wish compress the file on tar file format. But i have problem syntax in the line of the tar function. 

The error is 

[root at master ~]# python bkp_db.py 
  File "bkp_db.py", line 19
    tar = tarfile.open(dumpfile)+'.tar.gz','w:gz')
                                                 ^

Note: The 'dumpfile' is the variable for my dump generate with format db_02-27-14

......
tar = tarfile.open(dumpfile)+'.tar.gz','w:gz')
tar.add(os.path.join(dumpfile), arcname=dumpfile)
tar.close()
........

Wath is the correct sintax?


Thanks.





From joel.goldstick at gmail.com  Sun Mar  2 19:41:45 2014
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Sun, 2 Mar 2014 19:41:45 -0500
Subject: Error compressing tar file
In-Reply-To: <d9194b4f-f356-4597-8217-9ae43f586e4b@googlegroups.com>
References: <d9194b4f-f356-4597-8217-9ae43f586e4b@googlegroups.com>
Message-ID: <CAPM-O+y-tTKFhjRRZQ-cFGp4zKmQcScnUi5_Uh3OWYCUt_XayQ@mail.gmail.com>

On Mar 2, 2014 7:40 PM, "Mike" <miguelcoam at gmail.com> wrote:
>
> Hello,
> I have the script that make a backup file (this process is ok), but now i
wish compress the file on tar file format. But i have problem syntax in the
line of the tar function.
>
> The error is
>
> [root at master ~]# python bkp_db.py
>   File "bkp_db.py", line 19
>     tar = tarfile.open(dumpfile)+'.tar.gz','w:gz'))
>                                                  ^
>
> Note: The 'dumpfile' is the variable for my dump generate with format
db_02-27-14
>
> ......
> tar = tarfile.open(dumpfile)+'.tar.gz','w:gz')
> tar.add(os.path.join(dumpfile), arcname=dumpfile)
> tar.close()
> ........
>
> Wath is the correct sintax?
>
>
> Thanks.
>
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list
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From joel.goldstick at gmail.com  Sun Mar  2 19:43:40 2014
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Sun, 2 Mar 2014 19:43:40 -0500
Subject: Error compressing tar file
In-Reply-To: <CAPM-O+y-tTKFhjRRZQ-cFGp4zKmQcScnUi5_Uh3OWYCUt_XayQ@mail.gmail.com>
References: <d9194b4f-f356-4597-8217-9ae43f586e4b@googlegroups.com>
 <CAPM-O+y-tTKFhjRRZQ-cFGp4zKmQcScnUi5_Uh3OWYCUt_XayQ@mail.gmail.com>
Message-ID: <CAPM-O+xhK9FzWpdGTBBRioZemn-KMsg=wBuw+6gKvZa+J4g-ZA@mail.gmail.com>

On Mar 2, 2014 7:41 PM, "Joel Goldstick" <joel.goldstick at gmail.com> wrote:
>
>
> On Mar 2, 2014 7:40 PM, "Mike" <miguelcoam at gmail.com> wrote:
> >
> > Hello,
> > I have the script that make a backup file (this process is ok), but now
i wish compress the file on tar file format. But i have problem syntax in
the line of the tar function.
> >
> > The error is
> >
> > [root at master ~]# python bkp_db.py
> >   File "bkp_db.py", line 1
Oops. Remove ) after dumpfile
> >     tar = tarfile.open(dumpfile)+'.tar.gz','w:gz'))
>
> >                                                  ^
> >
> > Note: The 'dumpfile' is the variable for my dump generate with format
db_02-27-14
> >
> > ......
> > tar = tarfile.open(dumpfile)+'.tar.gz','w:gz')
> > tar.add(os.path.join(dumpfile), arcname=dumpfile)
> > tar.close()
> > ........
> >
> > Wath is the correct sintax?
> >
> >
> > Thanks.
> >
> >
> >
> > --
> > https://mail.python.org/mailman/listinfo/python-list
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From cs at zip.com.au  Sun Mar  2 19:44:58 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Mon, 3 Mar 2014 11:44:58 +1100
Subject: how to get bytes from bytearray without copying
In-Reply-To: <lf0h3g$m7r$1@ger.gmane.org>
References: <lf0h3g$m7r$1@ger.gmane.org>
Message-ID: <20140303004458.GA73815@cskk.homeip.net>

On 03Mar2014 01:07, Juraj Ivan?i? <juraj.ivancic at gmail.com> wrote:
> Is it possible to somehow 'steal' bytearray's buffer and make it a
> read-only bytes? I failed to find a way to do this, and would like
> to make sure.
> 
> My use case is, I would expect, fairly common. I read a certain
> (potentially very large) amount of data from the network into a
> pre-allocated bytearray. From that point on, this data is logically
> read-only. To prevent making redundant copies, I wrap it in a
> memoryview, and then slice and dice it. The problem with this
> memoryview is that it, and its slices, are considered writable, and
> thus cannot be hashed:
> 
> ValueError: cannot hash writable memoryview object

Have you considered subclassing memoryview and giving the subclass
a __hash__ method?

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

Mountain rescue teams insist the all climbers wear helmets, and fall haedfirst.
They are then impacted into a small globular mass easily stowed in a rucsac.
        - Tom Patey, who didnt, and wasnt


From breamoreboy at yahoo.co.uk  Sun Mar  2 19:49:28 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 03 Mar 2014 00:49:28 +0000
Subject: how to get bytes from bytearray without copying
In-Reply-To: <lf0h3g$m7r$1@ger.gmane.org>
References: <lf0h3g$m7r$1@ger.gmane.org>
Message-ID: <lf0jif$dpp$1@ger.gmane.org>

On 03/03/2014 00:07, Juraj Ivan?i? wrote:
> Is it possible to somehow 'steal' bytearray's buffer and make it a
> read-only bytes? I failed to find a way to do this, and would like to
> make sure.
>
> My use case is, I would expect, fairly common. I read a certain
> (potentially very large) amount of data from the network into a
> pre-allocated bytearray. From that point on, this data is logically
> read-only. To prevent making redundant copies, I wrap it in a
> memoryview, and then slice and dice it. The problem with this memoryview
> is that it, and its slices, are considered writable, and thus cannot be
> hashed:
>
> ValueError: cannot hash writable memoryview object
>
> The only way (AFAICT) to make this work is to first create a bytes
> object from bytearray, but this copies the data. I don't need this copy,
> so I'd like to avoid it, because of both principle and performance reasons.
>
> Is there any reason why bytearray isn't able to release/convert its
> buffer to bytes? I see that it has a clear() method which... well...
> clears it. The former would be much more useful.
>
> I would also be content if there is some way of making memoryview
> artificially read-only to avoid the above error.
>
> Any help/thoughts/comments are highly appreciated.
>

If your data is readonly why can't you simply read it as bytes in the 
first place?  Failing that from 
http://docs.python.org/3/library/stdtypes.html#memoryview

tobytes() - Return the data in the buffer as a bytestring. This is 
equivalent to calling the bytes constructor on the memoryview.

 >>> m = memoryview(b"abc")
 >>> m.tobytes()
b'abc'
 >>> bytes(m)
b'abc'

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ian.g.kelly at gmail.com  Sun Mar  2 19:55:48 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 2 Mar 2014 17:55:48 -0700
Subject: how to get bytes from bytearray without copying
In-Reply-To: <20140303004458.GA73815@cskk.homeip.net>
References: <lf0h3g$m7r$1@ger.gmane.org>
 <20140303004458.GA73815@cskk.homeip.net>
Message-ID: <CALwzidmKL25AR3MLf3EKNtk+C_BnopcZCmDDzDYK9j4ODDGifg@mail.gmail.com>

On Sun, Mar 2, 2014 at 5:44 PM, Cameron Simpson <cs at zip.com.au> wrote:
> Have you considered subclassing memoryview and giving the subclass
> a __hash__ method?

>>> class MyMemoryView(memoryview):
...     def __hash__(self): return 42
...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: type 'memoryview' is not an acceptable base type


From miguelcoam at gmail.com  Sun Mar  2 20:11:19 2014
From: miguelcoam at gmail.com (Mike)
Date: Sun, 2 Mar 2014 17:11:19 -0800 (PST)
Subject: Error compressing tar file
In-Reply-To: <d9194b4f-f356-4597-8217-9ae43f586e4b@googlegroups.com>
References: <d9194b4f-f356-4597-8217-9ae43f586e4b@googlegroups.com>
Message-ID: <2567f9c6-494d-4a69-b126-5e0e09c40a00@googlegroups.com>

El domingo, 2 de marzo de 2014 21:38:49 UTC-3, Mike  escribi?:
> Hello,
> 
> I have the script that make a backup file (this process is ok), but now i wish compress the file on tar file format. But i have problem syntax in the line of the tar function. 
> 
> 
> 
> The error is 
> 
> 
> 
> [root at master ~]# python bkp_db.py 
> 
>   File "bkp_db.py", line 19
> 
>     tar = tarfile.open(dumpfile)+'.tar.gz','w:gz')
> 
>                                                  ^
> 
> 
> 
> Note: The 'dumpfile' is the variable for my dump generate with format db_02-27-14
> 
> 
> 
> ......
> 
> tar = tarfile.open(dumpfile)+'.tar.gz','w:gz')
> 
> tar.add(os.path.join(dumpfile), arcname=dumpfile)
> 
> tar.close()
> 
> ........
> 
> 
> 
> Wath is the correct sintax?
> 
> 
> 
> 
> 
> Thanks.

Hello,
without ")" i have the same sintax error: 

[root at master ~]# python bkp_db.py 
Traceback (most recent call last):
  File "bkp_db.py", line 19, in <module>
    tar = tarfile.open(dumpfile + '.tar.gz','w:gz')
TypeError: unsupported operand type(s) for +: 'file' and 'str' 

Thanks.


From steve+comp.lang.python at pearwood.info  Sun Mar  2 20:16:47 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 03 Mar 2014 01:16:47 GMT
Subject: Password validation security issue
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
Message-ID: <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Sun, 02 Mar 2014 15:01:09 -0500, Roy Smith wrote:

> Security is as much about cryptography as it is about human factors and
> business drivers.  You can make things resistant to brute-force attacks
> by using longer keys, but people are still going to pick bad passwords.

Yes. But:

> You can force them to pick "good" passwords by rejecting their first 37
> choices, but all that does is encourage them to write the passwords down
> on sticky notes.

There is nothing wrong with writing passwords down on sticky notes. 
(Well, figuratively speaking. Perhaps not *literal* sticky notes, since 
they are too easy to lose.) You have to ask, what is the threat you are 
trying to defend against?

If your threat is that the Secret Police will break your door down at 
3am, and smash your fingers one at a time until you give them your 
passwords, then strong passwords that only you remember will not save you.

If the threat is that your little brother will log into your hotmail 
account and send rude messages to your school friends, then writing your 
password down on a Postit and sticking it on the computer is insecure, 
but keeping it in your wallet or purse may be secure enough.

Today, one of the biggest (but not the only) threats most people face is 
the mass theft of passwords from idiot organisations that store them in 
insecure databases as plain text. There's not much we, the users, can do 
about that, except complain complain complain when it happens. Possibly 
sue, on the basis that storing passwords as plain text is not within a 
million miles of best practice or even standard practice.

Another threat comes from black-hat hackers breaking your password. 
Whether they want *your* password specifically, or just picked your 
account randomly, this is where strong passwords can have a good effect. 
Until such time as an attacker can reach through the Internet to read the 
password on your Postit Note, writing down your strong password and 
keeping it by your computer is an effective way to counter this threat.


> And, yes, you can make things more secure with 2FA, but there's a cost
> there.  You have to purchase and manage the infrastructure.  More than
> that, there's lost business if potential customers prefer a competitor's
> product because it's easier to access.  Many of the known insecure
> systems we use today are not that way because the people who run them
> are stupid; they're that way because the people who run them have worked
> the numbers and decided the cost to implement more secure systems would
> exceed the risk exposure.

While in principle you are right, in practice I think that most of these 
people and organisations start from number of dodgy assumptions, starting 
with "Meh, it'll never happen...". They underestimate the risk, 
underestimate the consequences, ignore costs that don't apply solely to 
them (e.g. the cost of spam sent from tens of millions of compromised PCs 
and gmail accounts), overestimate the strength of their half-baked 
solutions, and ignore the portion of their user-base who actually does 
want better security.

When they do make a half-hearted attempt at security, it's often security 
theatre, e.g. I have a bank account with one bank that doesn't let you 
type your password, instead you have to click keys on a simulated 
keyboard on screen. You're limited to *six* (SIX!!!) case-insensitive 
alphanumeric characters, letters and digits only.

And then, to add insult to injury, they have the fecking cheek to hassle 
you every few months to change your insecure password for another 
insecure password, thus increasing the chance that you'll forgot what it 
is and lock yourself out of the account. This encourages people to choose 
even weaker passwords, so they won't forget them.

Another bank I use eschews such ridiculous "security" and actually 
provides you with a real cryptographic key for which you have to provide 
a passphrase. A passphrase limited to *eight* alphanumeric characters. 
And I think it is case-insensitive, although I haven't actually tried it.

I expect that these idiots spent more time, effort and money *preventing* 
their users from putting in strong passwords than they would have spent 
to allow strong passwords.

 
> We recently got a frothing email from a user, which basically said, "You
> farking idiots, you emailed me my password in plain text!"  It turns
> out, his user name was the same as his password and what we had sent him
> (in response to an account recovery query) was his username.  In
> response to that, we altered our account generation process to forbid
> passwords which are too similar to your chosen username or email
> address.  Which, of course, means we've taken one more step down the
> road to forcing our users to write their passwords on sticky notes.

That's a good thing.

People have managed physical keys for *centuries*. Yes, there are a class 
of threats where you lose your key, or someone steals it, or makes a 
copy, but the risks are well-understood and can be managed even by your 
grandmother. We have good solutions for those problems that work well, 
and many of them apply just as well to sticky notes with secure passwords 
written on them.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ned at nedbatchelder.com  Sun Mar  2 20:27:15 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Sun, 02 Mar 2014 20:27:15 -0500
Subject: Functional programming
In-Reply-To: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
Message-ID: <lf0lp4$1tr$1@ger.gmane.org>

On 3/2/14 6:14 PM, musicdenotation at gmail.com wrote:
> If Python is not a fnctional language, then which programming paradigmis dominant?
>

is_a_functional_language() is not a binary condition, yes or no.  It's a 
continuum.  Python has more functional constructs than Pascal, and fewer 
than Haskell.

-- 
Ned Batchelder, http://nedbatchelder.com



From ian.g.kelly at gmail.com  Sun Mar  2 20:27:40 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 2 Mar 2014 18:27:40 -0700
Subject: how to get bytes from bytearray without copying
In-Reply-To: <lf0h3g$m7r$1@ger.gmane.org>
References: <lf0h3g$m7r$1@ger.gmane.org>
Message-ID: <CALwzidncPvJS_aPJENre2HfOvV_PoY8mSV4PGA+i8FcwYPFc=A@mail.gmail.com>

On Sun, Mar 2, 2014 at 5:07 PM, Juraj Ivan?i? <juraj.ivancic at gmail.com> wrote:
> Is it possible to somehow 'steal' bytearray's buffer and make it a read-only
> bytes? I failed to find a way to do this, and would like to make sure.
>
> My use case is, I would expect, fairly common. I read a certain (potentially
> very large) amount of data from the network into a pre-allocated bytearray.
> From that point on, this data is logically read-only. To prevent making
> redundant copies, I wrap it in a memoryview, and then slice and dice it. The
> problem with this memoryview is that it, and its slices, are considered
> writable, and thus cannot be hashed:
>
> ValueError: cannot hash writable memoryview object
>
> The only way (AFAICT) to make this work is to first create a bytes object
> from bytearray, but this copies the data. I don't need this copy, so I'd
> like to avoid it, because of both principle and performance reasons.
>
> Is there any reason why bytearray isn't able to release/convert its buffer
> to bytes? I see that it has a clear() method which... well... clears it. The
> former would be much more useful.
>
> I would also be content if there is some way of making memoryview
> artificially read-only to avoid the above error.

Python 3.3 has a C API function to create a memoryview for a char*,
that can be made read-only.

    http://docs.python.org/3/c-api/memoryview.html#PyMemoryView_FromMemory

I don't see a way to do what you want in pure Python, apart from
perhaps writing an elaborate proxy class that would just be a poor
man's memoryview.  Or you could bite the bullet and copy everything
once at the start to create a bytes object, and then never have to
worry about it again.


From swdunning at cox.net  Sun Mar  2 20:36:04 2014
From: swdunning at cox.net (Scott W Dunning)
Date: Sun, 2 Mar 2014 18:36:04 -0700
Subject: Help with "Guess the number" script
In-Reply-To: <YXiF1n00H3bjUJS01XiGJE>
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <mailman.7516.1393691734.18130.python-list@python.org>
 <YJ7s1n00C3bjUJS01J7tQ2>
 <mailman.7555.1393722671.18130.python-list@python.org>
 <YXiF1n00H3bjUJS01XiGJE>
Message-ID: <7FA59B96-ABA7-4AD2-A4DD-6F50BDA2C2F6@cox.net>


On Mar 2, 2014, at 12:38 AM, Larry Hudson <orgnut at yahoo.com> wrote:
> 
> Another 'problem' is what you failed to mention in your post, but is apparent from the instructions that you posted -- this assignment is NOT the complete program, just the beginning of one.  Your instructor obviously wants you to work on (and understand) this program fragment before continuing with the rest of it.
> 
No it is the whole program I just didn?t post his entire instructs because they were like 5 pages.  Ifugured I just post what I was struggling with right now.  I?m hoping once I get past this first par I?ll be good to go.  Hopefully!

Scott

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From swdunning at cox.net  Sun Mar  2 20:40:21 2014
From: swdunning at cox.net (Scott W Dunning)
Date: Sun, 2 Mar 2014 18:40:21 -0700
Subject: Help with "Guess the number" script
In-Reply-To: <YRJP1n00U3bjUJS01RJQ57>
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <mailman.7516.1393691734.18130.python-list@python.org>
 <D9724003-3B31-4B30-AEFF-9AD34F581CB8@cox.net> <YRJP1n00U3bjUJS01RJQ57>
Message-ID: <B16295AB-B14D-4271-A9E5-71DB734B867D@cox.net>


On Mar 1, 2014, at 6:16 PM, Chris Angelico <rosuav at gmail.com> wrote:
> 
> Another consideration: Susan's code is written for Python 3, but you
> seemed to be using Python 2. You'll find that the code won't even run
> on your version of Python.
> 
> (If you have the chance, ask if the course writer would consider
> updating it to use Python 3. There's getting to be less and less
> reason to use Python 2 for any new projects; when you start a brand
> new system, you should be using Python 3 unless there's something
> holding you on the old version. So it's correspondingly more useful to
> learn Py3.)
> 
> ChrisA

I completely agree.  However, the instructor is wanting to use Python 2.7.6 because the book he is using for the course goes over 2.7.6.  Hopefully, once I learn more it will not be a huge jump to python 3.  

Scott



From cs at zip.com.au  Sun Mar  2 20:47:58 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Mon, 3 Mar 2014 12:47:58 +1100
Subject: how to get bytes from bytearray without copying
In-Reply-To: <CALwzidmKL25AR3MLf3EKNtk+C_BnopcZCmDDzDYK9j4ODDGifg@mail.gmail.com>
References: <CALwzidmKL25AR3MLf3EKNtk+C_BnopcZCmDDzDYK9j4ODDGifg@mail.gmail.com>
Message-ID: <20140303014758.GA40714@cskk.homeip.net>

On 02Mar2014 17:55, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Sun, Mar 2, 2014 at 5:44 PM, Cameron Simpson <cs at zip.com.au> wrote:
> > Have you considered subclassing memoryview and giving the subclass
> > a __hash__ method?
> 
> >>> class MyMemoryView(memoryview):
> ...     def __hash__(self): return 42
> ...
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> TypeError: type 'memoryview' is not an acceptable base type

Ah. The slices were going to be an issue too, anyway.

He could write a wrapper class with a __hash__ method, whose slices
themselves are also the wrapper class.

It raises the implementation bar only slightly.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

Please do not send me Microsoft Word files.
http://en.nothingisreal.com/wiki/Please_don't_send_me_Microsoft_Word_documents


From ian.g.kelly at gmail.com  Sun Mar  2 20:49:27 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 2 Mar 2014 18:49:27 -0700
Subject: Password validation security issue
In-Reply-To: <fe1cbc09-7004-42b4-b1ed-69b8083013eb@googlegroups.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <fe1cbc09-7004-42b4-b1ed-69b8083013eb@googlegroups.com>
Message-ID: <CALwzidn1UPv6MqUZFcfGouN+3ohUvZQrxMNq+6Ryj77uCjXiew@mail.gmail.com>

On Sun, Mar 2, 2014 at 4:10 PM, Renato <rvernucio at gmail.com> wrote:
> I would like to thank every one who posted a reply. I learnt a lot from you, guys! I appreciate your attention and your help :)
>
> I took a class on Computer Simulation last year. It was told that deterministic (pseudo-)random numbers are excellent for simulations, because they allow debugging and replication when using a seed(). But it was said that deterministic random numbers weren't indeed suitable for encryption and security issues in general. For this purpose, non-deterministc stochastic methods would be more indicated. I learnt a lot about deterministic random numbers generation in this course, like using Mersenne Twister algorithm, but I learnt nothing about encryption, since it wasn't in the scope of that course. Could you suggest some introductory material concerning encryption? I have an intermediate math background (calculus, linear algebra etc) and I'm willing to learn more about security matters.
>
> One last thing, about my original question. So, the only way of encapsulating a Python script content is to code a simple binary program to call it?

Another alternative would be to implement the script as a service that
runs under a separate account.  All the user can directly access is a
client script that sends requests to the service, which does the
actual work and is effectively encapsulated.

I'll also reiterate what others have written about protecting
passwords.  No matter how much you think you've locked down the
script, you shouldn't be storing plaintext passwords *anywhere*.
Remember that nothing that you code will ever be as secure as you
think it is.


From steve+comp.lang.python at pearwood.info  Sun Mar  2 20:50:39 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 03 Mar 2014 01:50:39 GMT
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <e24e0817-67d1-4dbd-b3ba-9250e735d261@googlegroups.com>
 <mailman.7453.1393562612.18130.python-list@python.org>
 <871tynznpd.fsf@elektro.pacujo.net>
 <53104798$0$11113$c3e8da3@news.astraweb.com>
 <mailman.7460.1393577227.18130.python-list@python.org>
 <87ha7jy2qs.fsf@elektro.pacujo.net>
 <mailman.7481.1393629442.18130.python-list@python.org>
 <87k3ceeq0m.fsf@elektro.pacujo.net>
 <mailman.7486.1393635051.18130.python-list@python.org>
 <87zjlad8q4.fsf@elektro.pacujo.net>
 <mailman.7492.1393638091.18130.python-list@python.org>
 <874n3irz04.fsf@elektro.pacujo.net>
 <mailman.7506.1393670936.18130.python-list@python.org>
 <87k3ceqhti.fsf@elektro.pacujo.net>
 <mailman.7517.1393693559.18130.python-list@python.org>
 <87mwh9969m.fsf@elektro.pacujo.net>
 <5312ed4b$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87ha7h9c40.fsf@elektro.pacujo.net>
 <53130b83$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <871tykal8o.fsf@elektro.pacujo.net>
Message-ID: <5313dfee$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Sun, 02 Mar 2014 13:33:11 +0200, Marko Rauhamaa wrote:

> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
> 
>> On Sun, 02 Mar 2014 11:35:43 +0200, Marko Rauhamaa wrote:
>>> Now, what kinds of object are those constants? We are not supposed to
>>> know or care.
>>
>> Incorrect. We are supposed to know and care.
> 
> Then, the documentation is seriously flawed. It gives no hint whatsoever
> on the nature of those objects.

"Seriously" flawed? I doubt it. It's a trivial, pedantic point, and I 
expect that most practising Python programmers will consider it too 
obvious to bother documenting the fact that flags meant for compatibility 
with POSIX operating systems are ints.

On the other hand, perhaps I am wrong and it is a documentation bug. Feel 
free to suggest a documentation patch on the bug tracker.


>> os.posix is exactly the sort of library I mentioned earlier when I said
>> sometimes you're constrained by compatibility with some other system.
>> In this case, the os module is explicitly designed to be compatible
>> with the POSIX interface, which is defined to use certain integer
>> values as flags. This is not an implementation choice which
>> implementers can change at will, it is part of the interface.
> 
> The values of those Python constants don't need to have any relationship
> with those of the underlying operating system.

In theory, they could be different. In practice, no they won't. You 
should be able to pass the Python constants directly to some C library 
which expects to see ints. It's a thin wrapper, not a bridge.


>> Python does not guarantee that there is only a single 1 instance.
> 
> Nobody has ever argued such a thing. I certainly haven't.

You may not have intended to, but by championing the use of "is", that is 
precisely what you have done. Using "is" tests for *identity*, not value. 
To get the behaviour you want, it requires those objects to be singletons.


> However, nothing in the API spec gives you the right to call the
> function with an integer.

But you do call the function with an integer. And if you don't, you get a 
type error that explicitly tells you that an integer is needed:

py> os.posix_fadvise(open("/tmp/spam").fileno(), 0, 100, None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: an integer is required


>> If you want to test whether a value is os.POSIX_FADV_RANDOM, the right
>> way is to compare that value for equality with os.POSIX_FADV_RANDOM,
>> not identity.
> 
> That might well be true but is not explicitly or implicitly specified in
> the documentation. (The os.SEEK_* constants are explicitly defined.)

Not everything needs to be documented explicitly. Would you rather the 
Python developers spend their time fixing bugs and improving the 
language, or ensuring that every trivial and obvious point is explicitly 
documented?

If you feel this is not a trivial or obvious point, and that it needs 
documenting, then feel free to contribute a documentation patch.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Sun Mar  2 20:54:47 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 03 Mar 2014 01:54:47 GMT
Subject: Functional programming
References: <mailman.7602.1393804722.18130.python-list@python.org>
Message-ID: <5313e0e6$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Mon, 03 Mar 2014 06:14:09 +0700, musicdenotation wrote:

> If Python is not a fnctional language, then which programming paradigmis
> dominant?

Object oriented and procedural are about equally dominant, with a strong 
influence from functional paradigm.

There are small amounts of imperative paradigm (e.g. the import and del 
statements), and you can use iterators and generators to program using a 
pipelining paradigm.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Sun Mar  2 21:02:10 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 03 Mar 2014 02:02:10 GMT
Subject: Error compressing tar file
References: <d9194b4f-f356-4597-8217-9ae43f586e4b@googlegroups.com>
 <2567f9c6-494d-4a69-b126-5e0e09c40a00@googlegroups.com>
Message-ID: <5313e2a1$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Sun, 02 Mar 2014 17:11:19 -0800, Mike wrote:

> without ")" i have the same sintax error:
> 
> [root at master ~]# python bkp_db.py
> Traceback (most recent call last):
>   File "bkp_db.py", line 19, in <module>
>     tar = tarfile.open(dumpfile + '.tar.gz','w:gz')
> TypeError: unsupported operand type(s) for +: 'file' and 'str'


That is not a syntax error. It is a type error. You cannot add a file 
object and a string object together.

Please inspect the value of dumpfile. You are treating it as if it were a 
string, but it looks like it is an open file object. I think that you 
probably expect this:

dumpfile = "path to some file"
tarfile.open(dumpfile + '.tar.gz','w:gz')


but what you actually have is probably something like this:


dumpfile = open("path to some file")
tarfile.open(dumpfile + '.tar.gz','w:gz')





-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Sun Mar  2 21:30:52 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 03 Mar 2014 02:30:52 GMT
Subject: Password validation security issue
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <fe1cbc09-7004-42b4-b1ed-69b8083013eb@googlegroups.com>
Message-ID: <5313e95b$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Sun, 02 Mar 2014 15:10:06 -0800, Renato wrote:

> I would like to thank every one who posted a reply. I learnt a lot from
> you, guys! I appreciate your attention and your help :)
> 
> I took a class on Computer Simulation last year. It was told that
> deterministic (pseudo-)random numbers are excellent for simulations,
> because they allow debugging and replication when using a seed(). But it
> was said that deterministic random numbers weren't indeed suitable for
> encryption and security issues in general. For this purpose,
> non-deterministc stochastic methods would be more indicated. 

Either you have misunderstood, or you have been told something incorrect.

You don't in general want non-deterministic stochastic randomness, 
because you can't control it and you can't make any guarantees about it. 
Stochastic randomness nearly always has deviations from uniformity which 
can be exploited, that is, it is less random than you might think. For 
example:

http://www.newscientist.com/article/mg21428644.500-roulette-beater-spills-
physics-behind-victory.html

http://en.wikipedia.org/wiki/Eudaemons


Nor do should you use deterministic PRNGs like the Mersenne Twister, not 
because they are deterministic, but because they aren't cryptographically 
strong.

The right approach is to use a deterministic PRNG which is deliberately 
designed for use in cryptographic applications, and then add in a source 
of entropy (which might be non-deterministic, like thermal noise or the 
output of radioactive decay). On Unix systems, the OS already does this 
for you:

http://sockpuppet.org/blog/2014/02/25/safely-generate-random-numbers/


> One last thing, about my original question. So, the only way of
> encapsulating a Python script content is to code a simple binary program
> to call it?

I don't understand this question. Can you explain more?




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ian.g.kelly at gmail.com  Sun Mar  2 20:52:40 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 2 Mar 2014 18:52:40 -0700
Subject: Password validation security issue
In-Reply-To: <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALwzidmTaS5QgeQcAbuU8T5e4Hp=u3e97z5vNKrUe24GysCSCg@mail.gmail.com>

On Sun, Mar 2, 2014 at 6:16 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> People have managed physical keys for *centuries*. Yes, there are a class
> of threats where you lose your key, or someone steals it, or makes a
> copy, but the risks are well-understood and can be managed even by your
> grandmother. We have good solutions for those problems that work well,
> and many of them apply just as well to sticky notes with secure passwords
> written on them.

I don't know how well the analogy holds up.  People protect their
keys, because a) if they lose them, they can't get into their house or
business, and b) if they're stolen, somebody else could gain access
and steal expensive items from them.  People are less likely to
protect their sticky notes, because a) nobody is going to steal a
piece of paper, and b) if it does go missing, the IT guy is just one
phone call away, and c) who would want to break into my desktop
anyway? I don't have any trade secrets in there.


From rosuav at gmail.com  Sun Mar  2 21:56:58 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 13:56:58 +1100
Subject: Password validation security issue
In-Reply-To: <CALwzidmTaS5QgeQcAbuU8T5e4Hp=u3e97z5vNKrUe24GysCSCg@mail.gmail.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <CALwzidmTaS5QgeQcAbuU8T5e4Hp=u3e97z5vNKrUe24GysCSCg@mail.gmail.com>
Message-ID: <CAPTjJmrJHPYnHCbn7bJTkaOj+-XuyHMbxbbVfByO1RrM976n1w@mail.gmail.com>

On Mon, Mar 3, 2014 at 12:52 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Sun, Mar 2, 2014 at 6:16 PM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> People have managed physical keys for *centuries*. Yes, there are a class
>> of threats where you lose your key, or someone steals it, or makes a
>> copy, but the risks are well-understood and can be managed even by your
>> grandmother. We have good solutions for those problems that work well,
>> and many of them apply just as well to sticky notes with secure passwords
>> written on them.
>
> I don't know how well the analogy holds up.  People protect their
> keys, because a) if they lose them, they can't get into their house or
> business, and b) if they're stolen, somebody else could gain access
> and steal expensive items from them.  People are less likely to
> protect their sticky notes, because a) nobody is going to steal a
> piece of paper, and b) if it does go missing, the IT guy is just one
> phone call away, and c) who would want to break into my desktop
> anyway? I don't have any trade secrets in there.

The greatest threats these days are from the network, not from someone
physically walking into an office. (That said, though, the low-hanging
fruit from walking into an office can be *extremely* tempting. Pulling
off a basic password leech off sticky notes is often so easy that it
can be done as a visitor, or at least as a pizza deliveryman.)
Ultimately, any network-accessible resource is protected by some
system of credentials that can be guessed; the only question is how
hard it is to guess. Any scheme to steal the password has to be easier
than guessing, or it's not worth it. Breaking a salted SHA-256 versus
XKCD 538 password cracking? Take your pick, but guessing a
six-character password beats both (being quicker than the one and more
subtle than the other).

Maybe salted SHA-256 isn't perfect, but it's certainly (a) a lot
better than plain text, unsalted hashes, or salted MD5, and (b) good
enough to raise the cracking of the hash above a lot of other
infiltration techniques.

ChrisA


From swdunning at cox.net  Sun Mar  2 22:44:47 2014
From: swdunning at cox.net (Scott W Dunning)
Date: Sun, 2 Mar 2014 20:44:47 -0700
Subject: Help with "Guess the number" script
In-Reply-To: <B16295AB-B14D-4271-A9E5-71DB734B867D@cox.net>
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <mailman.7516.1393691734.18130.python-list@python.org>
 <D9724003-3B31-4B30-AEFF-9AD34F581CB8@cox.net> <YRJP1n00U3bjUJS01RJQ57>
 <B16295AB-B14D-4271-A9E5-71DB734B867D@cox.net>
Message-ID: <3FDED793-DA02-4F9F-B431-33499B6949ED@cox.net>


On Mar 2, 2014, at 6:40 PM, Scott W Dunning <swdunning at cox.net> wrote:

This is what Im having trouble with now.  Here are the directions I?m stuck on and what I have so far, I?ll bold the part that?s dealing with the instructions if anyone could help me figure out where I?m going wrong.  

Thanks!

from random import randrange
randrange(1, 101)
from random import seed
seed(129)
    
def print_description():
    print """Welcome to Guess the Number.
    I have seleted a secret number in the range 1 ... 100.
    You must guess the number within 10 tries.
    I will tell you if you ar high or low, and
    I will tell you if you are hot or cold.\n"""
   
def get_guess(guess_number):
    promt = "(" + str(guess_number) +") Please enter a guess:"
    user_guess = raw_input(promt)
    user_guess = int(user_guess)
    return user_guess

def print_hints(secrets, guess):
    secret_number = secret
    guess = guess
    if guess < 0 or user_guess> 101:
        print "Out of range!"

def main():
    print_description()
    secret = randrange(1,101)
    current_guess = get_guess(1)
    if current_guess != secret:
        print_hints(secret_number, guess)
        current_guess = get_guess(2)
        
    if secret == current_guess:
        print "Congratulations, you win!"
    else:
        print "Please play again"
    print "The secret number was", secret        
            
main()
Just below the body of the get guess function, define a new function named print hints that takes two arguments. The first is a secret num- ber and is kept in a parameter named secret. The second is a guess made by the user and it is held in a parameter named guess.

The user?s guess is supposed to be within the range 1 ... 100. Write a conditional statement that checks if the guess is out of that range, and if it is print ?out of range? in the body of the print hints function.

Now we are going to give the user the option to make a second guess. You must add code to the main function immediately after assignment statement you wrote for task 7.

Write a conditional statement to check if the current guess does not match the secret number. If the numbers to not match, in the body of the conditional statement you will do two things.

(a)  call print hints to give the user hints,

(b)  re-assign current guess to the result of calling get guess with an

argument of 2. 
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From ben+python at benfinney.id.au  Sun Mar  2 22:52:10 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 03 Mar 2014 14:52:10 +1100
Subject: Help with "Guess the number" script
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <mailman.7516.1393691734.18130.python-list@python.org>
 <D9724003-3B31-4B30-AEFF-9AD34F581CB8@cox.net>
 <B16295AB-B14D-4271-A9E5-71DB734B867D@cox.net>
 <3FDED793-DA02-4F9F-B431-33499B6949ED@cox.net>
Message-ID: <857g8cj5w5.fsf@benfinney.id.au>

Scott W Dunning <swdunning at cox.net> writes:

> This is what Im having trouble with now.

Once again, Scott, this discussion should be happening at the Tutor
forum. Please don't continue the fragmentation of this discussion; keep
the discusson over at the Tutor forum.

-- 
 \      ?I like to fill my bathtub up with water, then turn the shower |
  `\       on and pretend I'm in a submarine that's been hit.? ?Steven |
_o__)                                                           Wright |
Ben Finney



From swdunning at cox.net  Sun Mar  2 23:04:17 2014
From: swdunning at cox.net (Scott W Dunning)
Date: Sun, 2 Mar 2014 21:04:17 -0700
Subject: Help with "Guess the number" script
In-Reply-To: <Yrua1n0023bjUJS01rubXG>
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <mailman.7516.1393691734.18130.python-list@python.org>
 <D9724003-3B31-4B30-AEFF-9AD34F581CB8@cox.net>
 <B16295AB-B14D-4271-A9E5-71DB734B867D@cox.net>
 <3FDED793-DA02-4F9F-B431-33499B6949ED@cox.net> <Yrua1n0023bjUJS01rubXG>
Message-ID: <A0EF691A-EAD3-4C05-9C5E-5729439C79CD@cox.net>


On Mar 2, 2014, at 8:52 PM, Ben Finney <ben+python at benfinney.id.au> wrote:
> 
> Once again, Scott, this discussion should be happening at the Tutor
> forum. Please don't continue the fragmentation of this discussion; keep
> the discusson over at the Tutor forum.
Sorry, I was just replying to replies to my post.  I get the posts through my email so it?s hard to distinguish, especially since people are responding under both.  I guess since people are responding it?s not that big a deal.

From steve at pearwood.info  Sun Mar  2 23:38:33 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 03 Mar 2014 04:38:33 GMT
Subject: Password validation security issue
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7618.1393814245.18130.python-list@python.org>
Message-ID: <53140749$0$2923$c3e8da3$76491128@news.astraweb.com>

On Sun, 02 Mar 2014 18:52:40 -0700, Ian Kelly wrote:

> On Sun, Mar 2, 2014 at 6:16 PM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> People have managed physical keys for *centuries*. Yes, there are a
>> class of threats where you lose your key, or someone steals it, or
>> makes a copy, but the risks are well-understood and can be managed even
>> by your grandmother. We have good solutions for those problems that
>> work well, and many of them apply just as well to sticky notes with
>> secure passwords written on them.
> 
> I don't know how well the analogy holds up.  People protect their keys,
> because a) if they lose them, they can't get into their house or
> business, and b) if they're stolen, somebody else could gain access and
> steal expensive items from them. 

A bit like the password to your bank account, or for that matter your 
Facebook account.


> People are less likely to protect
> their sticky notes, because a) nobody is going to steal a piece of
> paper, 

Oh really? Chances are you're wallet is *full* of pieces of paper that 
people would steal, given half the chance.


> and b) if it does go missing, the IT guy is just one phone call
> away, 

Last time I had to call my bank to unlock my account, it took two phone 
calls and nearly three hours of elapsed time. And I was lucky I didn't 
have to physically go in to a branch and show photo ID.


> and c) who would want to break into my desktop anyway? I don't
> have any trade secrets in there.

Who would want to steal somebody else's identity?

I'm not saying that people are born with an intuitive understanding of 
the security issues of a modern technological society. But they can 
*learn* (perhaps only after they get burned) that they need to protect 
their computer accounts, including their desktop.

Having learned that, they're screwed: even in the (uncommon) case that 
their account will support a cryptographically strong passphrase, most 
people need a dozen or more different passwords and/or passphrases. (I 
have about 50, only a dozen of which I keep in my head.) Who is going to 
remember a 12 character high-entropy string for an account they only use 
once a year? Most people have trouble remembering four-digit PINs if they 
don't use them regularly.

We cannot solve the social problem that people *don't* care about 
security with a technical solution, but we might be able to solve the 
problem that people *can't* remember sufficient passphrases and passwords 
for their needs. Lacking a technical solution for that, for most people, 
under many practical threat models, writing down your strong passwords on 
bits of paper which you then keep safe is better than using weak 
passwords, using one strong password for everything, or trying to 
remember a dozen strong, independent passwords.



-- 
Steven


From wuwei23 at gmail.com  Sun Mar  2 23:49:56 2014
From: wuwei23 at gmail.com (alex23)
Date: Mon, 03 Mar 2014 14:49:56 +1000
Subject: Coding a simple state machine in python
In-Reply-To: <mailman.7350.1393322496.18130.python-list@python.org>
References: <65ac9612-fd48-472a-b077-c802be96ece3@googlegroups.com>
 <mailman.7338.1393296954.18130.python-list@python.org>
 <mailman.7339.1393299066.18130.python-list@python.org>
 <leh95u$4aa$1@dont-email.me>
 <mailman.7350.1393322496.18130.python-list@python.org>
Message-ID: <lf11lk$k67$1@dont-email.me>

On 25/02/2014 8:01 PM, Peter Otten wrote:
> alex23 wrote:
>> No, the _easy_ solution is [find a suitable package on PyPI]
>
> Easy? By the time I have evaluated these I've written my own ;)

It's never writing a solution that's the problem...it's maintaining it 
over time :)



From rosuav at gmail.com  Mon Mar  3 00:44:26 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 16:44:26 +1100
Subject: Password validation security issue
In-Reply-To: <53140749$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7618.1393814245.18130.python-list@python.org>
 <53140749$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CAPTjJmoDRUwDXAFg23pPQqHFhY_N-3dddD_0c8qE0VihD3SnHg@mail.gmail.com>

On Mon, Mar 3, 2014 at 3:38 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> Oh really? Chances are you're wallet is *full* of pieces of paper that
> people would steal, given half the chance.

Alas no... around here, wallets get filled with pieces of plastic [1],
of which my wallet is sadly devoid. And I can't imagine anyone putting
effort into stealing my Gilbert & Sullivan Society membership card,
nor my coupon card for a half-price watch battery replacement on
condition that I take it back to some place that I don't go anywhere
near any more... But don't let that detract from your point :D

>> and b) if it does go missing, the IT guy is just one phone call
>> away,
>
> Last time I had to call my bank to unlock my account, it took two phone
> calls and nearly three hours of elapsed time. And I was lucky I didn't
> have to physically go in to a branch and show photo ID.

That's about par for the course. Worst part of it is when you lose
your connection and have to (a) go right back to the end of the caller
queue, (b) get through to a different agent, and therefore (c) have to
start over with the whole identifying-yourself thing. I wish I could
invoke tmux or GNU Screen on arrival,and then just reconnect.

This is, perhaps, the best argument in favour of password security.
The thought that someone might steal your identity is so vague and
hard to comprehend that it won't scare people; the possibility of
someone stealing money is "Oh but my bank will keep me safe" (whether
or not that's true is quite tangential); but explain that forgetting
your password (or having someone else figure out your password) means
having to call support? *That* is an incentive.

> Having learned that, they're screwed: even in the (uncommon) case that
> their account will support a cryptographically strong passphrase, most
> people need a dozen or more different passwords and/or passphrases. (I
> have about 50, only a dozen of which I keep in my head.) Who is going to
> remember a 12 character high-entropy string for an account they only use
> once a year? Most people have trouble remembering four-digit PINs if they
> don't use them regularly.

What if you create XKCD 936 passwords, and then have one "master
password file" in which you store, for each password, four words that
are synonyms for the originals, plus the first letters of them?
(Obviously your master password file (a) never leaves your own
computer, and (b) should itself be encrypted with some secure
password, and treated with extreme sensitivity. But that gets around
the "once a year" problem, as you'll refer to this one file any time
you need to check any of your rare passwords.) As a second line of
defense before contacting support, it feels plausible, but I've never
actually had an opportunity to try it.

Of course, the whole concept depends on being able to use long
memorable passwords. Any system that sets a maximum password length of
anything less than about 30-40 characters is causing its users
problems. There's almost never any reason to set a maximum at all.

ChrisA

[1] http://en.wikipedia.org/wiki/Polymer_banknote


From anikom15 at gmail.com  Mon Mar  3 01:16:31 2014
From: anikom15 at gmail.com (=?ISO-8859-1?Q?Westley_Mart=EDnez?=)
Date: Sun, 2 Mar 2014 22:16:31 -0800 (PST)
Subject: Origin of 'self'
Message-ID: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>

I understand that in an object method the first argument in the object itself, called self.  However, it doesn't have to be called self, and can be called anything.  So my question is why is it called self and not this like from C++ and Java.  It's kind of a silly question, but one that I'm curious about nevertheless.

Sincerely,
Westley Mart?nez


From davea at davea.name  Mon Mar  3 01:49:04 2014
From: davea at davea.name (Dave Angel)
Date: Mon, 3 Mar 2014 01:49:04 -0500 (EST)
Subject: Origin of 'self'
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
Message-ID: <lf18ch$fdr$1@ger.gmane.org>

 Westley Mart??nez <anikom15 at gmail.com> Wrote in message:
> I understand that in an object method the first argument in the object itself, called self.  However, it doesn't have to be called self, and can be called anything.  So my question is why is it called self and not this like from C++ and Java.  It's kind of a silly question, but one that I'm curious about nevertheless.
> 

I couldn't tell you the history,  but I can say it makes sense to
 me. In c++, this is a pointer,  and the name this seems
 reasonable.  But in python it's a reference,  a reference to
 myself. 

-- 
DaveA



From ian.g.kelly at gmail.com  Mon Mar  3 01:50:35 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 2 Mar 2014 23:50:35 -0700
Subject: Password validation security issue
In-Reply-To: <CAPTjJmoDRUwDXAFg23pPQqHFhY_N-3dddD_0c8qE0VihD3SnHg@mail.gmail.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7618.1393814245.18130.python-list@python.org>
 <53140749$0$2923$c3e8da3$76491128@news.astraweb.com>
 <CAPTjJmoDRUwDXAFg23pPQqHFhY_N-3dddD_0c8qE0VihD3SnHg@mail.gmail.com>
Message-ID: <CALwzidkWxOrrx7LrmGYXRHPpZqDGbb6Br2D-RZwE663P4egwXg@mail.gmail.com>

On Sun, Mar 2, 2014 at 10:44 PM, Chris Angelico <rosuav at gmail.com> wrote:
> Of course, the whole concept depends on being able to use long
> memorable passwords. Any system that sets a maximum password length of
> anything less than about 30-40 characters is causing its users
> problems. There's almost never any reason to set a maximum at all.

Well, there's usually *some* reason.  If you allow your users to set a
100-MB password then your system has to accept and attempt to verify
any 100-MB passwords that might get passed in, which opens you up to a
certain DoS attack.  Setting the limit at 8 characters though is
absurd and a probable indication of bad password handling.


From steve at pearwood.info  Mon Mar  3 01:52:40 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 03 Mar 2014 06:52:40 GMT
Subject: Origin of 'self'
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
Message-ID: <531426b8$0$2923$c3e8da3$76491128@news.astraweb.com>

On Sun, 02 Mar 2014 22:16:31 -0800, Westley Mart?nez wrote:

> I understand that in an object method the first argument in the object
> itself, called self.  However, it doesn't have to be called self, and
> can be called anything.  So my question is why is it called self and not
> this like from C++ and Java.  It's kind of a silly question, but one
> that I'm curious about nevertheless.

A better question is why C++ and Java used "this" instead of "self" like 
Smalltalk. It's fairly clear that Java copied C++, but why did C++ use 
"this"?


http://en.wikipedia.org/wiki/Comparison_of_programming_languages_%28object-oriented_programming%29#Special_variables


As far as I can tell, Simula 67 (the first OOP programming language) 
doesn't seem to use a standard name for the current instance, it appears 
to be unneeded. But Simula 67 was the inspiration for Smalltalk, invented 
by Alan Kay at Xerox PARC in the 1970s, and Smalltalk used "self". 
Virtually everything in OOP that followed was influenced by or derived 
from Smalltalk.



-- 
Steven


From ian.g.kelly at gmail.com  Mon Mar  3 02:03:18 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 3 Mar 2014 00:03:18 -0700
Subject: Origin of 'self'
In-Reply-To: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
Message-ID: <CALwzidmXuB-Dah0s5aN8=0pK4hnuZ0vFNryC896zBx9sKcR5Jw@mail.gmail.com>

On Sun, Mar 2, 2014 at 11:16 PM, Westley Mart?nez <anikom15 at gmail.com> wrote:
> I understand that in an object method the first argument in the object itself, called self.  However, it doesn't have to be called self, and can be called anything.  So my question is why is it called self and not this like from C++ and Java.  It's kind of a silly question, but one that I'm curious about nevertheless.

The idea of requiring references to attributes and methods of self to
be explicit comes from Modula-3; likely the naming convention follows
the same lineage.


From davea at davea.name  Mon Mar  3 02:10:13 2014
From: davea at davea.name (Dave Angel)
Date: Mon, 3 Mar 2014 02:10:13 -0500 (EST)
Subject: Help with "Guess the number" script
References: <43B63C46-3A2D-4374-8A42-EE931BA9A6C4@cox.net>
 <mailman.7516.1393691734.18130.python-list@python.org>
 <D9724003-3B31-4B30-AEFF-9AD34F581CB8@cox.net> <YRJP1n00U3bjUJS01RJQ57>
 <B16295AB-B14D-4271-A9E5-71DB734B867D@cox.net>
 <3FDED793-DA02-4F9F-B431-33499B6949ED@cox.net>
Message-ID: <lf19k8$uct$1@ger.gmane.org>

 Scott W Dunning <swdunning at cox.net> Wrote in message:
> 
Here are the directions I???m stuck on and what I have so far, I???ll bold the part 

That assumes that people can see which parts of your message are
 bold. Rather a poor assumption in a text list like these two
 python forums. You should be posting in text, not html.
 

Show some code and explain what you wish it would do. Then explain
 what it actually does, usually by pasting in an exception
 traceback,  or the console output. 

And respond on the tutor forum,  not here.


-- 
DaveA



From juraj.ivancic at gmail.com  Mon Mar  3 03:15:00 2014
From: juraj.ivancic at gmail.com (=?ISO-8859-2?Q?Juraj_Ivan=E8i=E6?=)
Date: Mon, 03 Mar 2014 09:15:00 +0100
Subject: how to get bytes from bytearray without copying
In-Reply-To: <20140303004458.GA73815@cskk.homeip.net>
References: <lf0h3g$m7r$1@ger.gmane.org>
 <20140303004458.GA73815@cskk.homeip.net>
Message-ID: <lf1dlq$94o$1@ger.gmane.org>

On 3.3.2014. 1:44, Cameron Simpson wrote:

>> ValueError: cannot hash writable memoryview object
>
> Have you considered subclassing memoryview and giving the subclass
> a __hash__ method?

I have, and then, when I failed to subclass it, I considered doing 
aggregation, and make it behave byte-like. But how to implement the 
overridden __hash__ method? It will still require at least *some* 
redundant copying. And there is the slicing thing... the whole idea 
started to feel like I was performing tonsillectomy through the anal cavity.




From juraj.ivancic at gmail.com  Mon Mar  3 03:52:25 2014
From: juraj.ivancic at gmail.com (=?ISO-8859-2?Q?Juraj_Ivan=E8i=E6?=)
Date: Mon, 03 Mar 2014 09:52:25 +0100
Subject: how to get bytes from bytearray without copying
In-Reply-To: <lf0jif$dpp$1@ger.gmane.org>
References: <lf0h3g$m7r$1@ger.gmane.org> <lf0jif$dpp$1@ger.gmane.org>
Message-ID: <lf1frv$2l6$1@ger.gmane.org>

On 3.3.2014. 1:49, Mark Lawrence wrote:

> If your data is readonly why can't you simply read it as bytes in the
> first place?  Failing that from
> http://docs.python.org/3/library/stdtypes.html#memoryview
>
> tobytes() - Return the data in the buffer as a bytestring. This is
> equivalent to calling the bytes constructor on the memoryview.
>
>   >>> m = memoryview(b"abc")
>   >>> m.tobytes()
> b'abc'
>   >>> bytes(m)
> b'abc'

Initially it has to be a bytearray because I read this data from a 
socket. My point is that once I have a bytearray x, then

m = memoryview(bytes(x))

is a very expensive way to make a read-only memoryview, opposed to

m = memoryview(x)

or (fictional)

m = memoryview(x, force_readonly=True)

especially if the x-es are many, large, and occur often.

I feel like memoryview's __hash__ is trying to be to smart for its own 
good, and that it should just return the damn hash like its name 
suggests, regardless of the value of 'writable' flag.








From juraj.ivancic at gmail.com  Mon Mar  3 04:09:56 2014
From: juraj.ivancic at gmail.com (=?ISO-8859-2?Q?Juraj_Ivan=E8i=E6?=)
Date: Mon, 03 Mar 2014 10:09:56 +0100
Subject: how to get bytes from bytearray without copying
In-Reply-To: <CALwzidncPvJS_aPJENre2HfOvV_PoY8mSV4PGA+i8FcwYPFc=A@mail.gmail.com>
References: <lf0h3g$m7r$1@ger.gmane.org>
 <CALwzidncPvJS_aPJENre2HfOvV_PoY8mSV4PGA+i8FcwYPFc=A@mail.gmail.com>
Message-ID: <lf1gsq$di7$1@ger.gmane.org>

On 3.3.2014. 2:27, Ian Kelly wrote:

> Python 3.3 has a C API function to create a memoryview for a char*,
> that can be made read-only.
>
>      http://docs.python.org/3/c-api/memoryview.html#PyMemoryView_FromMemory

Yes, this is probably what I'll do in absence of pure Python solution. 
Thanks for the tip.

> Or you could bite the bullet and copy everything
> once at the start to create a bytes object, and then never have to
> worry about it again.

That would be a surrender :-)



From nomail at invalid.com  Mon Mar  3 04:42:30 2014
From: nomail at invalid.com (ast)
Date: Mon, 3 Mar 2014 10:42:30 +0100
Subject: Reference
Message-ID: <53144e8d$0$2149$426a74cc@news.free.fr>

hello

Consider following code:

>>> A=7
>>> B=7
>>> A is B
True

I understand that there is a single object 7 somewhere in memory and
both variables A and B point toward this object 7

now do the same with a list:

>>> l1 = [1, 2]
>>> l2 = [1, 2]
>>> l1 is l2
False

It seems this time that there are 2 distincts objects [1, 2] in memory. l1 points
toward the first one and l2 points toward the second one.

if I change one, the second remains unchanged

>>> l1.append(3)
>>> l1
[1, 2, 3]
>>> l2
[1, 2]

I dont really understand why the behavior is different. 
Both integer 7 and list [1, 2] are objects. Why is it
different ?

thanks










From georg at python.org  Mon Mar  3 04:51:38 2014
From: georg at python.org (Georg Brandl)
Date: Mon, 03 Mar 2014 10:51:38 +0100
Subject: [RELEASED] Python 3.3.5 release candidate 2
Message-ID: <531450AA.3030005@python.org>

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On behalf of the Python development team, I'm happy to announce
the release of Python 3.3.5, release candidate 2.

Python 3.3.5 includes a fix for a regression in zipimport in 3.3.4
(see http://bugs.python.org/issue20621) and a few other bugs.

Python 3.3 includes a range of improvements of the 3.x series, as well
as easier porting between 2.x and 3.x.  In total, almost 500 API items
are new or improved in Python 3.3.  For a more extensive list of
changes in the 3.3 series, see

    http://docs.python.org/3.3/whatsnew/3.3.html

To download Python 3.3.5 visit:

    http://www.python.org/download/releases/3.3.5/


This is a preview release, please report any bugs to

     http://bugs.python.org/

The final release is scheduled one week from now.


Enjoy!

- -- 
Georg Brandl, Release Manager
georg at python.org
(on behalf of the entire python-dev team and 3.3's contributors)
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.22 (GNU/Linux)

iEYEARECAAYFAlMUUKoACgkQN9GcIYhpnLD5OACfTpRkcM9aXUx2XbiXoZtIgSE7
BqwAnjwpAuqc9lKJ0O3XOw5qDvDPYsNb
=EGuB
-----END PGP SIGNATURE-----


From ben+python at benfinney.id.au  Mon Mar  3 05:00:18 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 03 Mar 2014 21:00:18 +1100
Subject: Object identity (was: Reference)
References: <53144e8d$0$2149$426a74cc@news.free.fr>
Message-ID: <85y50rioul.fsf@benfinney.id.au>

"ast" <nomail at invalid.com> writes:

> >>> A=7
> >>> B=7
> >>> A is B
> True
>
> I understand that there is a single object 7 somewhere in memory and
> both variables A and B point toward this object 7

Try not to think in terms of ?point to?. Rather, the names ?A? and ?B?
are bound to that object.

The distinction is subtle; but it's important to realise that *all*
references in Python do this, and there's no way to talk about an object
in Python without using a reference. The ?pointer? model from other
languages doesn't exist in Python.

> now do the same with a list:
>
> >>> l1 = [1, 2]
> >>> l2 = [1, 2]
> >>> l1 is l2
> False
>
> It seems this time that there are 2 distincts objects [1, 2] in
> memory.

That's correct.

> I dont really understand why the behavior is different. Both integer 7
> and list [1, 2] are objects. Why is it different ?

Short answer: object identity is an implementation detail.

It's up to the Python implementation to decide when to re-use an object
when a new one is requested. No guarantee is made, when you ask to
create an object, that you won't get an existing one if that would work
just as well.

Since the integer object 7 is immutable, it will behave the same no
matter how many times you ask for a new one, the Python implementation
can choose to give you the same object. But it might not ? don't depend
on this!

Since two separate lists are mutable, each one can have a distinct
history after creation, so it would be less helpful to return an
existing list when you ask for a new one. But again, there's no
guarantee here either! A Python implementation might decide to give you
an existing list, if existing guarantees can be kept.

The moral is: Don't depend on differences in object identity. You can be
guaranteed that an object will retain its own identity, and its identity
will always be different from all other co-existing objects that have
different values. Beyond that, don't make any assumptions.

-- 
 \              ?Programs must be written for people to read, and only |
  `\        incidentally for machines to execute.? ?Abelson & Sussman, |
_o__)              _Structure and Interpretation of Computer Programs_ |
Ben Finney



From alister.ware at ntlworld.com  Mon Mar  3 05:06:59 2014
From: alister.ware at ntlworld.com (Alister)
Date: Mon, 03 Mar 2014 10:06:59 GMT
Subject: Functional programming
References: <mailman.7602.1393804722.18130.python-list@python.org>
Message-ID: <7vYQu.45397$hQ.28727@fx12.am4>

On Mon, 03 Mar 2014 06:14:09 +0700, musicdenotation wrote:

> If Python is not a fnctional language, then which programming paradigmis
> dominant?

Python follows the Pythonic paradigm :-)



-- 
Hope this helps some, sorry for not being able to do a brain dump.

	- Mike Stump helping a clueless user on the gcc mailing list


From nomail at invalid.com  Mon Mar  3 05:21:56 2014
From: nomail at invalid.com (ast)
Date: Mon, 3 Mar 2014 11:21:56 +0100
Subject: Object identity (was: Reference)
In-Reply-To: <mailman.7632.1393840833.18130.python-list@python.org>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <mailman.7632.1393840833.18130.python-list@python.org>
Message-ID: <531457cd$0$2032$426a74cc@news.free.fr>

thanks ben, that's clear


From bob.martin at excite.com  Mon Mar  3 05:26:18 2014
From: bob.martin at excite.com (Bob Martin)
Date: Mon, 03 Mar 2014 10:26:18 GMT
Subject: Functional programming
References: <mailman.7602.1393804722.18130.python-list@python.org>
Message-ID: <bnj3maFf2dhU3@mid.individual.net>

in 718085 20140302 231409 musicdenotation at gmail.com wrote:
>If Python is not a fnctional language, then which programming paradigmis dom=
>inant?=

Labels are always misleading.


From harrismh777 at gmail.com  Mon Mar  3 06:34:30 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 03:34:30 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
Message-ID: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>

hi folks,

Python Decimal Library dmath.py v0.3 Released

https://code.google.com/p/pythondecimallibrary/

This code provides the C accelerated decimal module with 
scientific/transcendental functions for arbitrary precision. 
I have also included pilib.py which is a PI library of historic
algorithms for generating PI, which uses dmath.py. 

I wish to thank Oscar, Wolfgang, Steven, Chris (and others)
for the help you gave me understanding decimal, particularly
format, rounding, and context managers. 

Everything is documented well (including issues) on the code
site, and things are working better, and are certainly cleaner. 
No doubt there are still bugs, but its getting closer.

Thanks again.

marcus


From rustompmody at gmail.com  Mon Mar  3 06:45:48 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 03:45:48 -0800 (PST)
Subject: Functional programming
In-Reply-To: <mailman.7612.1393810048.18130.python-list@python.org>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
Message-ID: <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>

On Monday, March 3, 2014 6:57:15 AM UTC+5:30, Ned Batchelder wrote:
> On 3/2/14 6:14 PM, musicdenotation wrote:
> > If Python is not a fnctional language, then which programming paradigmis dominant?

> is_a_functional_language() is not a binary condition, yes or no.  It's a 
> continuum.  Python has more functional constructs than Pascal, and fewer 
> than Haskell.

I find this the most agreeable answer. I would add:

There are really two continuaa:
the 'CAN' and the 'CANNOT' (sounds 180 deg apart but they are actually
rather independent)

As Ned says on the CAN spectrum python sits between standard
imperative languages like C,Pascal and Haskell, in fact coming quite close
to Haskell.

However it is also useful to consider the CANNOT spectrum for
beginners/pedagogical purposes.

If you start a beginner on a language like Haskell which CANNOT:
- express iteration except with recursion
- cannot have assignments (and therefore anything remotely like a normal
program variable; variables are only ever math variables)
- cannot do a 'type-incorrect' expression like
>>> [1,2] + [[3,4],[5]]
[1, 2, [3, 4], [5]]

the beginner will develop a significantly different mind-set than
starting from a python-like language



From harrismh777 at gmail.com  Mon Mar  3 07:02:26 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 04:02:26 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
Message-ID: <f2c66036-6e55-4d90-8e25-820129a15be4@googlegroups.com>

On Monday, March 3, 2014 5:34:30 AM UTC-6, Mark H. Harris wrote:
> hi folks,

Terry,  I posted this mod as an idea on python-ideas, as you suggested.
Also, I made the additional suggestion that decimal floating point be 
considered as the primary floating point type for python4.x, with an 
optional binary floating type (2.345b) if the user might like that.

As Steven pointed out last week, we have a fast module now for decimal
floating point; it seems this is a good time to consider this as a serious 
idea for future python(s).

marcus



From rosuav at gmail.com  Mon Mar  3 07:20:37 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 23:20:37 +1100
Subject: Functional programming
In-Reply-To: <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
Message-ID: <CAPTjJmqUkXvNw-mCifm6pWOB8M0RbV06FLr_xjdP=s9FZbbw6Q@mail.gmail.com>

On Mon, Mar 3, 2014 at 10:45 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> - cannot do a 'type-incorrect' expression like
>>>> [1,2] + [[3,4],[5]]
> [1, 2, [3, 4], [5]]

What do you mean by "type-incorrect"? This is adding two lists and
getting back a list. Seems perfectly correct to me.

ChrisA


From marcuscvj at gmail.com  Mon Mar  3 07:32:39 2014
From: marcuscvj at gmail.com (Marcus)
Date: Mon, 3 Mar 2014 04:32:39 -0800 (PST)
Subject: Iterate through a list and try log in to a website with urllib and re
Message-ID: <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3@googlegroups.com>

Hello,

I'm trying to use urllib and urllib2 to open an url + login_data in a for loop. How can I display when successfully logged in and how to show when the login is denied? 

I've tried use this:

html_content = urllib2.urlopen(url).read()
re.findall('ERROR: The password you entered for the username USER is incorrect.', html_content)

1. I want to try an if statement in a for loop
2. Iterate through a list and when the first password in the list is denied. It shall continue with the next password in the list and try that one.
3. When it's successfully logged in the program will stop the loop and print out the password that matches.

I'm stuck and need some help creating this.


From marcuscvj at gmail.com  Mon Mar  3 07:35:41 2014
From: marcuscvj at gmail.com (Marcus)
Date: Mon, 3 Mar 2014 04:35:41 -0800 (PST)
Subject: Iterate through a list and try log in to a website with urllib
 and re
In-Reply-To: <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3@googlegroups.com>
References: <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3@googlegroups.com>
Message-ID: <1177d930-a3c4-4152-818c-33d5172083f8@googlegroups.com>

This is the code right now: http://pastebin.com/pE1YZX2K


From rosuav at gmail.com  Mon Mar  3 07:44:27 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 23:44:27 +1100
Subject: Iterate through a list and try log in to a website with urllib
 and re
In-Reply-To: <CAPTjJmpeugby-hK=vD3JqKwj08pwVfCujXegeQ=kLPD072EwXw@mail.gmail.com>
References: <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3@googlegroups.com>
 <1177d930-a3c4-4152-818c-33d5172083f8@googlegroups.com>
 <CAPTjJmpeugby-hK=vD3JqKwj08pwVfCujXegeQ=kLPD072EwXw@mail.gmail.com>
Message-ID: <CAPTjJmp9C1jyy7V7eG95SVWZKYapiem5e=uFg38BCyFttT4jfA@mail.gmail.com>

On Mon, Mar 3, 2014 at 11:44 PM, Chris Angelico <rosuav at gmail.com> wrote:
> So basically, you're doing a dictionary attack. May I ask why you're
> doing this, exactly?


From rosuav at gmail.com  Mon Mar  3 07:45:44 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 23:45:44 +1100
Subject: Iterate through a list and try log in to a website with urllib
 and re
In-Reply-To: <CAPTjJmpeugby-hK=vD3JqKwj08pwVfCujXegeQ=kLPD072EwXw@mail.gmail.com>
References: <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3@googlegroups.com>
 <1177d930-a3c4-4152-818c-33d5172083f8@googlegroups.com>
 <CAPTjJmpeugby-hK=vD3JqKwj08pwVfCujXegeQ=kLPD072EwXw@mail.gmail.com>
Message-ID: <CAPTjJmoXnY-pGQ7sLqrxz+iP-JTXnbKqK5wXd4gPs8Q_68cjuw@mail.gmail.com>

On Mon, Mar 3, 2014 at 11:44 PM, Chris Angelico <rosuav at gmail.com> wrote:
> So basically, you're doing a dictionary attack. May I ask why you're
> doing this, exactly?

oops, misclicked.

I note that the user name 'alex' does not appear to match your name.
I'm going to want a good reason for this code to be written, else
you're on your own - I don't intend to help you steal someone else's
password.

ChrisA


From rosuav at gmail.com  Mon Mar  3 07:44:20 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 3 Mar 2014 23:44:20 +1100
Subject: Iterate through a list and try log in to a website with urllib
 and re
In-Reply-To: <1177d930-a3c4-4152-818c-33d5172083f8@googlegroups.com>
References: <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3@googlegroups.com>
 <1177d930-a3c4-4152-818c-33d5172083f8@googlegroups.com>
Message-ID: <CAPTjJmpeugby-hK=vD3JqKwj08pwVfCujXegeQ=kLPD072EwXw@mail.gmail.com>

On Mon, Mar 3, 2014 at 11:35 PM, Marcus <marcuscvj at gmail.com> wrote:
> This is the code right now: http://pastebin.com/pE1YZX2K

That looks short enough to include in-line, no need to point us to an
external site :)

So basically, you're doing a dictionary attack. May I ask why you're
doing this, exactly?

ChrisA


From marcuscvj at gmail.com  Mon Mar  3 07:51:31 2014
From: marcuscvj at gmail.com (Marcus)
Date: Mon, 3 Mar 2014 04:51:31 -0800 (PST)
Subject: Iterate through a list and try log in to a website with urllib
 and re
In-Reply-To: <mailman.7635.1393850747.18130.python-list@python.org>
References: <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3@googlegroups.com>
 <1177d930-a3c4-4152-818c-33d5172083f8@googlegroups.com>
 <CAPTjJmpeugby-hK=vD3JqKwj08pwVfCujXegeQ=kLPD072EwXw@mail.gmail.com>
 <mailman.7635.1393850747.18130.python-list@python.org>
Message-ID: <d276dd23-f611-4665-8fc3-569f2a855d9e@googlegroups.com>

Yes, it's only for my own use on my local WordPress installation. Only educational use. 


From rosuav at gmail.com  Mon Mar  3 08:00:11 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 00:00:11 +1100
Subject: Iterate through a list and try log in to a website with urllib
 and re
In-Reply-To: <d276dd23-f611-4665-8fc3-569f2a855d9e@googlegroups.com>
References: <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3@googlegroups.com>
 <1177d930-a3c4-4152-818c-33d5172083f8@googlegroups.com>
 <CAPTjJmpeugby-hK=vD3JqKwj08pwVfCujXegeQ=kLPD072EwXw@mail.gmail.com>
 <mailman.7635.1393850747.18130.python-list@python.org>
 <d276dd23-f611-4665-8fc3-569f2a855d9e@googlegroups.com>
Message-ID: <CAPTjJmr50eJi2=7UdupjreB+k_kn+cHZDDAtJdOzTmW2QMXwQg@mail.gmail.com>

On Mon, Mar 3, 2014 at 11:51 PM, Marcus <marcuscvj at gmail.com> wrote:
> Yes, it's only for my own use on my local WordPress installation. Only educational use.

What are you trying to learn, exactly? How to break into a WP site?

Still dubious.

ChrisA


From marcuscvj at gmail.com  Mon Mar  3 08:05:38 2014
From: marcuscvj at gmail.com (Marcus)
Date: Mon, 3 Mar 2014 05:05:38 -0800 (PST)
Subject: Iterate through a list and try log in to a website with urllib
 and re
In-Reply-To: <mailman.7637.1393851620.18130.python-list@python.org>
References: <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3@googlegroups.com>
 <1177d930-a3c4-4152-818c-33d5172083f8@googlegroups.com>
 <CAPTjJmpeugby-hK=vD3JqKwj08pwVfCujXegeQ=kLPD072EwXw@mail.gmail.com>
 <mailman.7635.1393850747.18130.python-list@python.org>
 <d276dd23-f611-4665-8fc3-569f2a855d9e@googlegroups.com>
 <mailman.7637.1393851620.18130.python-list@python.org>
Message-ID: <948ed27b-e9ec-4062-97d7-2b4b0bb05672@googlegroups.com>

It's not that hard to find a program that does this already. But I'm trying to learn how to use these modules to create this. I've started it and now i want to complete it so I can create another program and learn more about other stuff, maybe a Twitter script or something. How do I learn when not practice? 


From harrismh777 at gmail.com  Mon Mar  3 08:09:31 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 05:09:31 -0800 (PST)
Subject: Reference
In-Reply-To: <53144e8d$0$2149$426a74cc@news.free.fr>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
Message-ID: <ed7cc56a-6988-4f8e-9a95-f5bbfa1dbc4a@googlegroups.com>

On Monday, March 3, 2014 3:42:30 AM UTC-6, ast wrote:

> Consider following code:
> 
> >>> A=7
> >>> B=7
> >>> A is B
> True

The names A and B are both bound to the same object (7). 
You will discover that this is True for all small ints less
than 257;  on CPython3.3.4.  I just checked it.   :)

Its just more efficient to do this for small ints because they 
are immutable (1) and because they are used for frequently (2).

As somebody pointed out last week, don't use "is" for ints and 
strings (generally speaking). Value is what's important here,
not identity. My python coding is yet simple and straight
forward enough that I have not had a need yet for "is". 

Cheers
marcus



From oscar.j.benjamin at gmail.com  Mon Mar  3 08:34:40 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Mon, 3 Mar 2014 13:34:40 +0000
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
Message-ID: <CAHVvXxTyQQZXK+His0=W13wnGMxcgFUFrnitdt=Ds7RFBGs8cQ@mail.gmail.com>

On 3 March 2014 11:34, Mark H. Harris <harrismh777 at gmail.com> wrote:
> hi folks,
>
> Python Decimal Library dmath.py v0.3 Released
>
> https://code.google.com/p/pythondecimallibrary/

Hi Mark,

Is this available on PyPI? It seems there already is a "dmath" package
on PyPI that was written by someone else some time ago so you might
need to use a different name:
https://pypi.python.org/pypi/dmath/0.9


Oscar


From mailinglists at vanwingerde.nl  Mon Mar  3 08:35:41 2014
From: mailinglists at vanwingerde.nl (Jaap van Wingerde)
Date: Mon, 3 Mar 2014 13:35:41 +0000
Subject: modification time in Python - Django: datetime != datetime :-(
Message-ID: <20140303133541.66fccbbb@lia.custard.shrl.nl>

Django views.py:
...
pwd = os.path.dirname(os.path.realpath(__file__ ))
home_lastmod =  strftime('%Y-%m-%dT%H:%m:%SZ',gmtime(os.path.getmtime(pwd+'/templates/art_index.html')))
...

The template gives a wrong modification time: "2014-03-02T19:03:55Z".

...
jaap at liakoster:~$ python
Python 2.7.3 (default, Jan  2 2013, 13:56:14) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import os, time
>>> from time import
>>> gmtime
>>> time.strftime('%Y-%m-%dT%H:%m:%SZ',gmtime(os.path.getmtime('/var/django/test2/art/templates/art_index.html')))  
'2014-03-02T19:03:55Z'
>>> quit()  
jaap at liakoster:~$ ls --full-time /var/django/test2/art/templates/art_index.html
-rwxrwx--- 1 lia www-data 2456 2014-03-02 19:16:55.568139590 +0000 /var/django/test2/art/templates/art_index.html
jaap at liakoster:~$ 
...

ls gives the right modification time. What is wrong?

...
jaap at liakoster:~$ lsb_release -a
No LSB modules are available.
Distributor ID:	Debian
Description:	Debian GNU/Linux 7.4 (wheezy)
Release:	7.4
Codename:	wheezy
jaap at liakoster:~$ uname -a
Linux liakoster.shrl.nl 3.2.0-4-amd64 #1 SMP Debian 3.2.46-1+deb7u1 x86_64 GNU/Linux
jaap at liakoster:~$ 
...

-- 
Jaap van Wingerde
e-mail: 1234567890 at vanwingerde.nl


From roy at panix.com  Mon Mar  3 08:41:10 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 03 Mar 2014 08:41:10 -0500
Subject: Password validation security issue
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <CALwzidmTaS5QgeQcAbuU8T5e4Hp=u3e97z5vNKrUe24GysCSCg@mail.gmail.com>
 <mailman.7619.1393815421.18130.python-list@python.org>
Message-ID: <roy-759EB5.08411003032014@news.panix.com>

In article <mailman.7619.1393815421.18130.python-list at python.org>,
 Chris Angelico <rosuav at gmail.com> wrote:

> The greatest threats these days are from the network, not from someone
> physically walking into an office. (That said, though, the low-hanging
> fruit from walking into an office can be *extremely* tempting. Pulling
> off a basic password leech off sticky notes is often so easy that it
> can be done as a visitor, or at least as a pizza deliveryman.)

Doesn't even require physical presence.  With the ubiquity of various 
video chat applications, as long as the sticky note is in the field of 
view of the camera, you've leaked the password.  With the right 
lighting, I wouldn't be surprised if you could pick up the reflection of 
a sticky note in somebody's eyeglasses.

So, here's my own (embarrassing) story of password leaking.  Back when 
smartphones were new, I had one of the early Palm Treos.  I decided a 
good place to store my passwords was as fields on my own card.  What I 
didn't realize was that if I beamed[*] my card to somebody, I was also 
giving them all my passwords, mostly because it had never occurred to me 
that I might want to beam my card to somebody.  Until somebody else in 
my office got another smart phone that had beaming capabilities and we 
decided to see how it worked.  It occurred to me as soon as we completed 
the first experiment.

I used to work at <big company> which had a typical big company IT 
department which enforced all sorts of annoying pseudo-security rules.  
As far as I could figure out, however, all you needed to get them to 
reset anybody's password and tell you the new one was to know their 
employee ID number (visible on the front of their ID badge), and to make 
the call from their desk phone.

[*] Beaming: a prehistoric technology which allows exchange of data over 
an infrared light beam.


From roy at panix.com  Mon Mar  3 08:47:16 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 03 Mar 2014 08:47:16 -0500
Subject: Iterate through a list and try log in to a website with urllib
 and re
References: <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3@googlegroups.com>
Message-ID: <roy-435B9C.08471603032014@news.panix.com>

In article <fc7c1c7d-7811-4e58-a999-1f2e9b297cd3 at googlegroups.com>,
 Marcus <marcuscvj at gmail.com> wrote:
 
> I'm trying to use urllib and urllib2 to open an url + login_data in a for 
> loop.

Step 1: Ignore all that crap and get http://www.python-requests.org/

> How can I display when successfully logged in and how to show when the 
> login is denied? 
> 
> I've tried use this:
> 
> html_content = urllib2.urlopen(url).read()
> re.findall('ERROR: The password you entered for the username USER is 
> incorrect.', html_content)

In the ideal case, whatever you're talking to will return a success or 
failure indication in the HTTP status code.

Lacking that, it will at least return something intended to be parsed 
(like JSON).

Lacking that (and, unfortunately, common), you're reduced to 
screen-scraping.  But, if you've got to do that, at least use a tool 
like lxml or BeautifulSoup to parse the HTML.


From rustompmody at gmail.com  Mon Mar  3 08:48:00 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 05:48:00 -0800 (PST)
Subject: Functional programming
In-Reply-To: <mailman.7633.1393849247.18130.python-list@python.org>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
Message-ID: <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>

On Monday, March 3, 2014 5:50:37 PM UTC+5:30, Chris Angelico wrote:
> On Mon, Mar 3, 2014 at 10:45 PM, Rustom Mody  wrote:
> > - cannot do a 'type-incorrect' expression like
> >>>> [1,2] + [[3,4],[5]]
> > [1, 2, [3, 4], [5]]

> What do you mean by "type-incorrect"? This is adding two lists and
> getting back a list. Seems perfectly correct to me.


Here's the behavior from an (old version of) haskell.

Unfortunately modern versions give a less helpful error message
'++' is list-append, '?' is the prompt

? [1,2] + [[3,4],[5]]                   
ERROR: Type error in application
*** expression     : [1,2] + [[3,4],[5]]
*** term           : [1,2]
*** type           : [Int]
*** does not match : [[Int]]

IOW [1,2,[3,4],[5]]
is a type-wise ill-formed expression just as in python
[[1,2])
is syntax-wise ill-formed

Is it worth having such a restriction?
Thats a different argument...


From rustompmody at gmail.com  Mon Mar  3 08:51:21 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 05:51:21 -0800 (PST)
Subject: Functional programming
In-Reply-To: <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
Message-ID: <3a913df5-5034-4d9c-985a-a46a7015d6cd@googlegroups.com>

On Monday, March 3, 2014 7:18:00 PM UTC+5:30, Rustom Mody wrote:

> Unfortunately modern versions give a less helpful error message
> '++' is list-append, '?' is the prompt

> ? [1,2] + [[3,4],[5]]                   

Whoops Wrong cut-paste!

? [1,2] ++ [[3,4],[5]]
ERROR: Type error in application
*** expression     : [1,2] ++ [[3,4],[5]]
*** term           : [1,2]
*** type           : [Int]
*** does not match : [[Int]]

? 



From rosuav at gmail.com  Mon Mar  3 08:55:45 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 00:55:45 +1100
Subject: Password validation security issue
In-Reply-To: <roy-759EB5.08411003032014@news.panix.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
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 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <CALwzidmTaS5QgeQcAbuU8T5e4Hp=u3e97z5vNKrUe24GysCSCg@mail.gmail.com>
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 <roy-759EB5.08411003032014@news.panix.com>
Message-ID: <CAPTjJmpt6E-xsKSs5-bts2pjC6y0EgM7HwGJocHp5_YBARywzw@mail.gmail.com>

On Tue, Mar 4, 2014 at 12:41 AM, Roy Smith <roy at panix.com> wrote:
> I used to work at <big company> which had a typical big company IT
> department which enforced all sorts of annoying pseudo-security rules.
> As far as I could figure out, however, all you needed to get them to
> reset anybody's password and tell you the new one was to know their
> employee ID number (visible on the front of their ID badge), and to make
> the call from their desk phone.

Technically, that's a separate vulnerability. If you figure out
someone else's password, you can log in as that person and nobody is
any the wiser (bar detailed logs eg of IP addresses). Getting a
password reset will at least alert the person on their next login.
That may or may not be safe, of course. Doing a password reset at
4:30pm the day before someone goes away for two months might give you
free reign for that time *and* might not even arouse suspicions ("I
can't remember my password after the break, can you reset it
please?").

But it's an attack vector that MUST be considered, which is why I
never tell the truth in any "secret question / secret answer" boxes.
Why some sites think "mother's maiden name" is at all safe is beyond
my comprehension. And that's not counting the ones that I can't answer
because I can't find the "NaN" key on my keyboard, like "Surname of
first girlfriend". *twiddle thumbs*

ChrisA


From rosuav at gmail.com  Mon Mar  3 09:00:17 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 01:00:17 +1100
Subject: Functional programming
In-Reply-To: <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
Message-ID: <CAPTjJmog4z6qxfMG70RamGw_ZSj_C1bCB4eX0XGJBhens9eEAg@mail.gmail.com>

On Tue, Mar 4, 2014 at 12:48 AM, Rustom Mody <rustompmody at gmail.com> wrote:
> ? [1,2] + [[3,4],[5]]
> ERROR: Type error in application
> *** expression     : [1,2] + [[3,4],[5]]
> *** term           : [1,2]
> *** type           : [Int]
> *** does not match : [[Int]]
>
> IOW [1,2,[3,4],[5]]
> is a type-wise ill-formed expression just as in python
> [[1,2])
> is syntax-wise ill-formed
>
> Is it worth having such a restriction?
> Thats a different argument...

How do you know that [1,2] is a list that must contain nothing but
integers? By extension, it's also a list that must contain positive
integers less than three, so adding [5] violates that. And [] is a
list that must contain nothing, ergo it can't be added to, although
(since it contains nothing) it can be added to anything.

Some languages do let you specify element types (Pike has an "array"
type that can hold anything, or you can say "array(int)" to restrict
it to integers; you could also say "array(int(1..2))" to specify what
I said above, if you actually intend that), but without a declaration
from the programmer, it's dangerous to assume there's an error.

ChrisA


From rosuav at gmail.com  Mon Mar  3 09:08:52 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 01:08:52 +1100
Subject: modification time in Python - Django: datetime != datetime :-(
In-Reply-To: <20140303133541.66fccbbb@lia.custard.shrl.nl>
References: <20140303133541.66fccbbb@lia.custard.shrl.nl>
Message-ID: <CAPTjJmrp9Ca5zyfo75NKcX_ik0Qi4kOcjhhY6EEWKQ-xJx7KQg@mail.gmail.com>

On Tue, Mar 4, 2014 at 12:35 AM, Jaap van Wingerde
<mailinglists at vanwingerde.nl> wrote:
>>>> time.strftime('%Y-%m-%dT%H:%m:%SZ',gmtime(os.path.getmtime('/var/django/test2/art/templates/art_index.html')))
> '2014-03-02T19:03:55Z'
>>>> quit()
> jaap at liakoster:~$ ls --full-time /var/django/test2/art/templates/art_index.html
> -rwxrwx--- 1 lia www-data 2456 2014-03-02 19:16:55.568139590 +0000 /var/django/test2/art/templates/art_index.html

See if ls is actually giving you ctime rather than mtime - compare the
results if you ask for os.path.getctime.

ChrisA


From rustompmody at gmail.com  Mon Mar  3 09:08:11 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 06:08:11 -0800 (PST)
Subject: Functional programming
In-Reply-To: <mailman.7641.1393855219.18130.python-list@python.org>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
Message-ID: <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>

On Monday, March 3, 2014 7:30:17 PM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 4, 2014 at 12:48 AM, Rustom Mody wrote:
> > ? [1,2] + [[3,4],[5]]
> > ERROR: Type error in application
> > *** expression     : [1,2] + [[3,4],[5]]
> > *** term           : [1,2]
> > *** type           : [Int]
> > *** does not match : [[Int]]
> > IOW [1,2,[3,4],[5]]
> > is a type-wise ill-formed expression just as in python
> > [[1,2])
> > is syntax-wise ill-formed
> > Is it worth having such a restriction?
> > Thats a different argument...

> How do you know that [1,2] is a list that must contain nothing but
> integers? By extension, it's also a list that must contain positive
> integers less than three, so adding [5] violates that. And [] is a
> list that must contain nothing, ergo it can't be added to, although
> (since it contains nothing) it can be added to anything.

If 'integer-less-than-3' were a type then yes there would be this
problem. More generally, if types could overlap then automatic
type-inference is impossible

Whether all thats good is as I earlier said a different argument

The OP asked about FP and so its appropriate to mention how python's
and standard FPL's choices differ


From ndbecker2 at gmail.com  Mon Mar  3 09:17:24 2014
From: ndbecker2 at gmail.com (Neal Becker)
Date: Mon, 3 Mar 2014 09:17:24 -0500 (EST)
Subject: How security holes happen
References: <CAB6mnxLbE3up2Aa0dK+84OKq1GvNCZOpqD=BJvDmp3sdVV--Bw@mail.gmail.com>
Message-ID: <lf22t1$sgh$1@ger.gmane.org>

 Charles R Harris <charlesr.harris at gmail.com> Wrote in message:
> _______________________________________________
> NumPy-Discussion mailing list
> NumPy-Discussion at scipy.org
> http://mail.scipy.org/mailman/listinfo/numpy-discussion
> 

Imo the lesson here is never write in low level c. Use modern
 languages with well designed exception handling.
-- 




----Android NewsGroup Reader----
http://www.piaohong.tk/newsgroup



From invalid at invalid.invalid  Mon Mar  3 09:18:09 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Mon, 3 Mar 2014 14:18:09 +0000 (UTC)
Subject: [OT] Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
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 <levn78$mkq$1@reader1.panix.com> <levnqa$hjk$2@ger.gmane.org>
 <mailman.7591.1393788264.18130.python-list@python.org>
Message-ID: <lf22v1$ag5$1@reader1.panix.com>

On 2014-03-02, Chris Angelico <rosuav at gmail.com> wrote:
> On Mon, Mar 3, 2014 at 3:55 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>> On 02/03/2014 16:45, Grant Edwards wrote:
>>>
>>>
>>> That's irrelevent.  The actual location of the memory containing the
>>> struct object (static, stack, heap, shared) doesn't matter.  The
>>> address of the first field in a struture object _is_ the address of
>>> the structure object.
>>>
>>
>> You say struture, I'll say structure, let's call the whole thing off :)
>
>:)
>
> Note that, technically, Grant is correct as long as you grant (heh)
> that a structure may have an invisible member, the virtual function
> table pointer. C++ only (I don't believe C has virtual functions -
> but it may have grown them in one of the newer standards), so in C,
> all members are public.

Yes. I was talking about C, not C++.  I made that quite clear in
portions of my post that have been elided.  In C there is no such
thing as a virtual table pointer.

-- 
Grant Edwards               grant.b.edwards        Yow! We have DIFFERENT
                                  at               amounts of HAIR --
                              gmail.com            


From rosuav at gmail.com  Mon Mar  3 09:23:01 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 01:23:01 +1100
Subject: Functional programming
In-Reply-To: <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
Message-ID: <CAPTjJmpgYjaoofcJq5vR-vS-8n8_KjpeQdvwyS_y_fZNKd5q5w@mail.gmail.com>

On Tue, Mar 4, 2014 at 1:08 AM, Rustom Mody <rustompmody at gmail.com> wrote:
>> How do you know that [1,2] is a list that must contain nothing but
>> integers? By extension, it's also a list that must contain positive
>> integers less than three, so adding [5] violates that. And [] is a
>> list that must contain nothing, ergo it can't be added to, although
>> (since it contains nothing) it can be added to anything.
>
> If 'integer-less-than-3' were a type then yes there would be this
> problem. More generally, if types could overlap then automatic
> type-inference is impossible
>

First, does Haskell allow this?

? [1,2,'foo'] ++ [3,4,'bar']

If not, then find some other form of the expression that has the same
point, and substitute in for the below. And then: which of these is
permitted?

? [1,2] ++ [3,4,'bar']
? [1,2,'foo'] ++ [3,4]
? [] ++ [3,4,'bar']
? [1,2,'foo'] ++ []
? ([1,2,'foo'] ++ []) ++ [3,4,'bar']
? [1,2,'foo'] ++ ([] ++ [3,4,'bar'])

If it's okay to have heterogeneous lists, how do you tell it that your
[1,2] is actually going to get strings in it later, and that it's okay
to combine it with one that has strings?

With Pike, that's all based on the variable type. (There is type
inference; the type of an array containing just 3 and 4 is
"array(int(3..4))", but it's acceptable to add that to an array
containing the string "asdf", which itself has type
"array(string(97..115))" - the combination would be "array(int(3..4) |
string(97..115))", which gets a bit wordy.) I can't assign an
array(string) to a variable that's been declared as taking array(int).
But I can assign an array(int) to a variable declared as accepting
array(int|string), and then I can append a string to it, because
that's legal based on the destination.

ChrisA


From rosuav at gmail.com  Mon Mar  3 09:25:14 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 01:25:14 +1100
Subject: [OT] Can global variable be passed into Python function?
In-Reply-To: <lf22v1$ag5$1@reader1.panix.com>
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87sird7wuw.fsf@handshake.de> <le7fso$a83$1@ger.gmane.org>
 <8454E8CB-E6E3-452F-8E54-9A77BFF34EC2@gmail.com>
 <1m3gg9lbf2ln5m2kbki954t17mqni3b20k@4ax.com>
 <mailman.7262.1393078476.18130.python-list@python.org>
 <53095145$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <877g8mcg1m.fsf@elektro.pacujo.net>
 <mailman.7286.1393151578.18130.python-list@python.org>
 <87ob1yay9m.fsf@elektro.pacujo.net>
 <08aa32de-cd51-4888-bd60-2c2b53d86ecc@googlegroups.com>
 <mailman.7319.1393265975.18130.python-list@python.org>
 <leg7au$ckp$2@reader1.panix.com>
 <mailman.7560.1393732703.18130.python-list@python.org>
 <levn78$mkq$1@reader1.panix.com> <levnqa$hjk$2@ger.gmane.org>
 <mailman.7591.1393788264.18130.python-list@python.org>
 <lf22v1$ag5$1@reader1.panix.com>
Message-ID: <CAPTjJmq1duYRyiuuFUkQjxLe6-ZCRXd_wPs_QfScA1VXV+duWA@mail.gmail.com>

On Tue, Mar 4, 2014 at 1:18 AM, Grant Edwards <invalid at invalid.invalid> wrote:
>> Note that, technically, Grant is correct as long as you grant (heh)
>> that a structure may have an invisible member, the virtual function
>> table pointer. C++ only (I don't believe C has virtual functions -
>> but it may have grown them in one of the newer standards), so in C,
>> all members are public.
>
> Yes. I was talking about C, not C++.  I made that quite clear in
> portions of my post that have been elided.  In C there is no such
> thing as a virtual table pointer.

I wasn't certain of the newer C standards. C's been gaining all sorts
of features, not all of which are necessary, and it's entirely
possible based on my current knowledge that C specifies #include
<antigravity> ...

ChrisA


From mailinglists at vanwingerde.nl  Mon Mar  3 09:28:21 2014
From: mailinglists at vanwingerde.nl (Jaap van Wingerde)
Date: Mon, 3 Mar 2014 14:28:21 +0000
Subject: modification time in Python - Django: datetime != datetime :-(
In-Reply-To: <CAPTjJmrp9Ca5zyfo75NKcX_ik0Qi4kOcjhhY6EEWKQ-xJx7KQg@mail.gmail.com>
References: <20140303133541.66fccbbb@lia.custard.shrl.nl>
 <CAPTjJmrp9Ca5zyfo75NKcX_ik0Qi4kOcjhhY6EEWKQ-xJx7KQg@mail.gmail.com>
Message-ID: <20140303142821.0d24c929@lia.custard.shrl.nl>

Op <Tue, 4 Mar 2014 01:08:52 +1100> schreef Chris Angelico <rosuav at gmail.com> in bericht <CAPTjJmrp9Ca5zyfo75NKcX_ik0Qi4kOcjhhY6EEWKQ-xJx7KQg at mail.gmail.com>:

> See if ls is actually giving you ctime rather than mtime - compare the
> results if you ask for os.path.getctime.

jaap at liakoster:~$ python
Python 2.7.3 (default, Jan  2 2013, 13:56:14) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import os, time
>>> from time import gmtime
>>> time.strftime('%Y-%m-%dT%H:%m:%SZ',gmtime(os.path.getmtime('/var/django/test2/art/templates/art_index.html')))
'2014-03-02T19:03:55Z'
>>> time.strftime('%Y-%m-%dT%H:%m:%SZ',gmtime(os.path.getctime('/var/django/test2/art/templates/art_index.html')))
'2014-03-02T19:03:55Z'
>>> quit()
jaap at liakoster:~$ ls --full-time /var/django/test2/art/templates/art_index.html
-rwxrwx--- 1 lia www-data 2456 2014-03-02 19:16:55.568139590 +0000 /var/django/test2/art/templates/art_index.html
jaap at liakoster:~$ 

ls is giving me the modified time.


From harrismh777 at gmail.com  Mon Mar  3 09:27:56 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 06:27:56 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <mailman.7638.1393853709.18130.python-list@python.org>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <mailman.7638.1393853709.18130.python-list@python.org>
Message-ID: <d8b16fb4-f82b-47af-a920-dbbe728cf6c7@googlegroups.com>

On Monday, March 3, 2014 7:34:40 AM UTC-6, Oscar Benjamin wrote:

 > Python Decimal Library dmathlib.py v0.3 Released

> https://code.google.com/p/pythondecimallibrary/

> Is this available on PyPI? It seems there already is a "dmath" package
> on PyPI that was written by someone else some time ago so you might
> need to use a different name:

> Oscar

hi Oscar; thanks again for your help.

Yes, I actually intended to call it dmathlib.py at first, and then had my 
brain stuck on dmath, partly because several folks threw that name 
around, and partly because I got used to abbreviating it and forgot 
to fix things up name-wise. 

[ Done ]

Actually, code.google tries to help folks with that because if the name 
is taken you have to create a unique name; which I did, but I forgot to 
fix up all the references and heading.  Thanks again for keeping me
accountable. 

Kind regards,
marcus


From invalid at invalid.invalid  Mon Mar  3 09:29:38 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Mon, 3 Mar 2014 14:29:38 +0000 (UTC)
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
Message-ID: <lf23ki$ag5$2@reader1.panix.com>

On 2014-03-03, ast <nomail at invalid.com> wrote:
> hello
>
> Consider following code:
>
>>>> A=7
>>>> B=7
>>>> A is B
> True
>
> I understand that there is a single object 7 somewhere in memory

Maybe, maybe not.  Integer are immutable, so that's allowed but not
required. In CPython, that's true for small integers, but that is an
implementation detail, and you shouldn't depend on it.

> and both variables A and B point toward this object 7

They might.  They might not.

> now do the same with a list:
>
>>>> l1 = [1, 2]
>>>> l2 = [1, 2]
>>>> l1 is l2
> False
>
> It seems this time that there are 2 distincts objects [1, 2] in
> memory.

Yep.  Lists are mutable, therefore each literal produces a distinct
object.

> l1 points toward the first one and l2 points toward the
> second one.

Yep.

> I dont really understand why the behavior is different. 
> Both integer 7 and list [1, 2] are objects. Why is it
> different ?

Integer objects are immutable (they can't change value), therefore you
can reuse them without causing problems.  Lists are mutable (you can
change the values in them), so you can't reuse them.

-- 
Grant Edwards               grant.b.edwards        Yow! Maybe I should have
                                  at               asked for my Neutron Bomb
                              gmail.com            in PAISLEY --


From rustompmody at gmail.com  Mon Mar  3 09:38:33 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 06:38:33 -0800 (PST)
Subject: Functional programming
In-Reply-To: <mailman.7644.1393856584.18130.python-list@python.org>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
Message-ID: <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>

On Monday, March 3, 2014 7:53:01 PM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 4, 2014 at 1:08 AM, Rustom Mody wrote:
> >> How do you know that [1,2] is a list that must contain nothing but
> >> integers? By extension, it's also a list that must contain positive
> >> integers less than three, so adding [5] violates that. And [] is a
> >> list that must contain nothing, ergo it can't be added to, although
> >> (since it contains nothing) it can be added to anything.
> > If 'integer-less-than-3' were a type then yes there would be this
> > problem. More generally, if types could overlap then automatic
> > type-inference is impossible

> First, does Haskell allow this?

> ? [1,2,'foo'] ++ [3,4,'bar']

> If not, then find some other form of the expression that has the same
> point, and substitute in for the below. And then: which of these is
> permitted?


Dunno what you mean/whats the 'point'


> ? [1,2] ++ [3,4,'bar']
> ? [1,2,'foo'] ++ [3,4]
> ? [] ++ [3,4,'bar']
> ? [1,2,'foo'] ++ []
> ? ([1,2,'foo'] ++ []) ++ [3,4,'bar']
> ? [1,2,'foo'] ++ ([] ++ [3,4,'bar'])

> If it's okay to have heterogeneous lists, 

Its not.  None of the above work

If you want the (semantic) equivalent of python's [1,2,'foo']
you need to make an explicit union Int and String and its that
*single* union type's elements that must go in.

In all cases its always a single type. And so
sum([1,2,[3])
is a syntax error unlike python where its a runtime error




From rosuav at gmail.com  Mon Mar  3 10:01:47 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 02:01:47 +1100
Subject: Functional programming
In-Reply-To: <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
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 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
Message-ID: <CAPTjJmpqEdaYUsUWPVhP-J3X+8Q5FvXOAFMxHf85crq0-Yvz4Q@mail.gmail.com>

On Tue, Mar 4, 2014 at 1:38 AM, Rustom Mody <rustompmody at gmail.com> wrote:
> If you want the (semantic) equivalent of python's [1,2,'foo']
> you need to make an explicit union Int and String and its that
> *single* union type's elements that must go in.
>
> In all cases its always a single type. And so
> sum([1,2,[3])

Okay. That's how the declaration goes, then. So how do you tell it
that 1 isn't an Int, it's a member of the union of Int and String? How
do you create a list which has [Int_String(1), Int_String(2)] and is
therefore allowed to be added to [Int_String('foo')] ? Can you do that
with literals?

This is why it's tricky to put rules in based on type inference. The
programmer's intent isn't in the picture. If Python ever acquires that
kind of restriction ("here's a list that can contain only this type /
these types of object"), I would hope that it's left up to the
programmer, not the compiler, to stipulate. That's how it is with Pike
(if you just say "array", it can take anything), and that's the only
way to be sure the programmer doesn't have to fight the language.

You said earlier

>> On Tue, Mar 4, 2014 at 1:08 AM, Rustom Mody wrote:
>> > If 'integer-less-than-3' were a type then yes there would be this
>> > problem. More generally, if types could overlap then automatic
>> > type-inference is impossible

The type "Int" overlaps with the type "Union of Int and String". How
is that resolved? Type inference ignores unions? That's the only way I
can think of. Hence the original difficulty of type-inferring on a
list that isn't complete yet.

ChrisA


From andywu1206 at gmail.com  Mon Mar  3 10:22:22 2014
From: andywu1206 at gmail.com (Harry Wood)
Date: Mon, 3 Mar 2014 07:22:22 -0800 (PST)
Subject: How to create a voting website by Python and Flask?
Message-ID: <39d907df-7fc9-4843-ab8a-cb6a16e668a9@googlegroups.com>

How to create a voting website by Python and Flask? I studying Python and Flask for some months, and

 - Now I have some Python & Flask basic skills.
 - I need some advices like following example: 
Step 1: You could writing an voting application by Python Step 2: You could build a website by Flask ...
Thanks very much!


From harrismh777 at gmail.com  Mon Mar  3 10:22:47 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 07:22:47 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <mailman.7638.1393853709.18130.python-list@python.org>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <mailman.7638.1393853709.18130.python-list@python.org>
Message-ID: <466dcd2a-4198-47ac-9797-d4c993e03d61@googlegroups.com>

On Monday, March 3, 2014 7:34:40 AM UTC-6, Oscar Benjamin wrote:
> On 3 March 2014 11:34, Mark H. Harris  wrote:
> 

> Is this available on PyPI? It seems there already is a "dmath" package
> on PyPI that was written by someone else some time ago so you might 
> need to use a different name:

> Oscar

Oscar, thanks again for your help, and for keeping me accountable. I did
intend on using the naming convention pythondecimallibrary but got 
dmath stuck in my mind from the discussions earlier last week. At any 
rate the naming problem is fixed.  Thanks again.

Python3.3 Decimal Library v0.3 is Released  here:

  https://code.google.com/p/pythondecimallibrary/

*pdeclib.py* is the decimal library, and *pilib.py* is the PI library.


marcus


From rustompmody at gmail.com  Mon Mar  3 10:28:38 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 07:28:38 -0800 (PST)
Subject: Functional programming
In-Reply-To: <mailman.7647.1393858917.18130.python-list@python.org>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
Message-ID: <8dbc91d9-42e5-4404-ba10-7a6d8e404986@googlegroups.com>

On Monday, March 3, 2014 8:31:47 PM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 4, 2014 at 1:38 AM, Rustom Mody  wrote:
> > If you want the (semantic) equivalent of python's [1,2,'foo']
> > you need to make an explicit union Int and String and its that
> > *single* union type's elements that must go in.
> > In all cases its always a single type. And so
> > sum([1,2,[3])

> Okay. That's how the declaration goes, then. So how do you tell it
> that 1 isn't an Int, it's a member of the union of Int and String? How
> do you create a list which has [Int_String(1), Int_String(2)] and is
> therefore allowed to be added to [Int_String('foo')] ? Can you do that
> with literals?

Mmmm This is getting a bit OT for a python list
Anyway here goes
The Union type is called Either.
Its got two constructors -- Left and Right -- better to think of them as
tags to not confuse with OO constructors.
The names Left and Right seem to be a bit meaningless because the Either
type is completely generic -- any types S and T can be 'unioned' as
Either S T
where the S components look like Left x for x : S
and the T components look like Right x for x : T

So python's [1,2,"foo"] is
written as
[Left 1, Left 2, Right "foo"]

> This is why it's tricky to put rules in based on type inference. The
> programmer's intent isn't in the picture. If Python ever acquires that
> kind of restriction ("here's a list that can contain only this type /
> these types of object"), I would hope that it's left up to the
> programmer, not the compiler, to stipulate. That's how it is with Pike
> (if you just say "array", it can take anything), and that's the only
> way to be sure the programmer doesn't have to fight the language.

> You said earlier

> >> On Tue, Mar 4, 2014 at 1:08 AM, Rustom Mody wrote:
> >> > If 'integer-less-than-3' were a type then yes there would be this
> >> > problem. More generally, if types could overlap then automatic
> >> > type-inference is impossible

> The type "Int" overlaps with the type "Union of Int and String". How
> is that resolved? 

By decreeing "no overlap!" :-)

Left 1 : Either Int String
whereas 1 : Int

Strictly speaking 'union' should be called 'disjoint union' but this is
so universal in programming that its dropped as redundant.

Heck even C's union is disjoint! If we have

union u
{ 
  int i;
  char c;
};

union u x;

Now you cant interchange the usages of x x.i and x.c



From rustompmody at gmail.com  Mon Mar  3 10:52:29 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 07:52:29 -0800 (PST)
Subject: Reference
In-Reply-To: <53144e8d$0$2149$426a74cc@news.free.fr>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
Message-ID: <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>

On Monday, March 3, 2014 3:12:30 PM UTC+5:30, ast wrote:
> hello

> Consider following code:

> >>> A=7
> >>> B=7
> >>> A is B
> True

> I understand that there is a single object 7 somewhere in memory and
> both variables A and B point toward this object 7

> now do the same with a list:

> >>> l1 = [1, 2]
> >>> l2 = [1, 2]
> >>> l1 is l2
> False

> It seems this time that there are 2 distincts objects [1, 2] in memory. l1 points
> toward the first one and l2 points toward the second one.

> if I change one, the second remains unchanged

> >>> l1.append(3)
> >>> l1
> [1, 2, 3]
> >>> l2
> [1, 2]

> I dont really understand why the behavior is different. 
> Both integer 7 and list [1, 2] are objects. Why is it
> different ?

Short answer: Avoid using 'is'. 

Long answer: http://www.beyondwilber.ca/healing-thinking/non-identity-korzybski.html

Pragmatic answer: Think of 'is' as a short-form for 'machine-rep-is'
And use machine representations with the same alacrity that a
C programmer uses inline assembly


From david.froger at inria.fr  Mon Mar  3 11:01:49 2014
From: david.froger at inria.fr (David Froger)
Date: Mon, 03 Mar 2014 17:01:49 +0100
Subject: How to create a voting website by Python and Flask?
In-Reply-To: <39d907df-7fc9-4843-ab8a-cb6a16e668a9@googlegroups.com>
References: <39d907df-7fc9-4843-ab8a-cb6a16e668a9@googlegroups.com>
Message-ID: <20140303160149.11066.53696@fl-58186.rocq.inria.fr>

Quoting Harry Wood (2014-03-03 16:22:22)
> How to create a voting website by Python and Flask? I studying Python and Flask for some months, and
> 
>  - Now I have some Python & Flask basic skills.
>  - I need some advices like following example: 
> Step 1: You could writing an voting application by Python Step 2: You could build a website by Flask ...
> Thanks very much!
> -- 
> https://mail.python.org/mailman/listinfo/python-list

Hi Harry,

For example:

You define an URL, something like /voting. Used with a GET request, the Python
function associated to the /voting URL renders and returns a template
containing a form. You can create the form using Flask-WTF, and use
Flask-Bootstrap to make your page looks better. The user fill the form, and
submit it (POST request on /voting). Here, the function associated with
/voting get the form data, and store it in a database.

You define a second URL, /results, which on a GET request reads your database
and returns the results by rendering a template, something like
render_template('result.html', result=result)

Hope it helps!
David


From python at mrabarnett.plus.com  Mon Mar  3 11:29:51 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 03 Mar 2014 16:29:51 +0000
Subject: Password validation security issue
In-Reply-To: <CAPTjJmpt6E-xsKSs5-bts2pjC6y0EgM7HwGJocHp5_YBARywzw@mail.gmail.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <CALwzidmTaS5QgeQcAbuU8T5e4Hp=u3e97z5vNKrUe24GysCSCg@mail.gmail.com>
 <mailman.7619.1393815421.18130.python-list@python.org>
 <roy-759EB5.08411003032014@news.panix.com>
 <CAPTjJmpt6E-xsKSs5-bts2pjC6y0EgM7HwGJocHp5_YBARywzw@mail.gmail.com>
Message-ID: <5314ADFF.6000909@mrabarnett.plus.com>

On 2014-03-03 13:55, Chris Angelico wrote:
> On Tue, Mar 4, 2014 at 12:41 AM, Roy Smith <roy at panix.com> wrote:
>> I used to work at <big company> which had a typical big company IT
>> department which enforced all sorts of annoying pseudo-security rules.
>> As far as I could figure out, however, all you needed to get them to
>> reset anybody's password and tell you the new one was to know their
>> employee ID number (visible on the front of their ID badge), and to make
>> the call from their desk phone.
>
> Technically, that's a separate vulnerability. If you figure out
> someone else's password, you can log in as that person and nobody is
> any the wiser (bar detailed logs eg of IP addresses). Getting a
> password reset will at least alert the person on their next login.
> That may or may not be safe, of course. Doing a password reset at
> 4:30pm the day before someone goes away for two months might give you
> free reign for that time *and* might not even arouse suspicions ("I
> can't remember my password after the break, can you reset it
> please?").
>
> But it's an attack vector that MUST be considered, which is why I
> never tell the truth in any "secret question / secret answer" boxes.
> Why some sites think "mother's maiden name" is at all safe is beyond
> my comprehension. And that's not counting the ones that I can't answer
> because I can't find the "NaN" key on my keyboard, like "Surname of
> first girlfriend". *twiddle thumbs*
>
I don't think you're obliged to answer such questions truthfully.

Q: Surname of first girlfriend?
A: Luxury Yacht



From oscar.j.benjamin at gmail.com  Mon Mar  3 11:44:16 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Mon, 3 Mar 2014 16:44:16 +0000
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <466dcd2a-4198-47ac-9797-d4c993e03d61@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <mailman.7638.1393853709.18130.python-list@python.org>
 <466dcd2a-4198-47ac-9797-d4c993e03d61@googlegroups.com>
Message-ID: <CAHVvXxRCLd+O8aQg0Yi6=VFMUyXxNYfOUWy9NnHdhsit1Ne6kg@mail.gmail.com>

On 3 March 2014 15:22, Mark H. Harris <harrismh777 at gmail.com> wrote:
> On Monday, March 3, 2014 7:34:40 AM UTC-6, Oscar Benjamin wrote:
>> On 3 March 2014 11:34, Mark H. Harris  wrote:
>>
>> Is this available on PyPI?
>
> Python3.3 Decimal Library v0.3 is Released  here:
>
>   https://code.google.com/p/pythondecimallibrary/
>
> *pdeclib.py* is the decimal library, and *pilib.py* is the PI library.

Is it on PyPI though? I was referring to a PyPI name so that people
could install it with "pip install pdeclib" (or whatever you called
it). That's how open source Python projects are usually distributed.


Oscar


From steve+comp.lang.python at pearwood.info  Mon Mar  3 11:46:38 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 03 Mar 2014 16:46:38 GMT
Subject: Password validation security issue
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <CALwzidmTaS5QgeQcAbuU8T5e4Hp=u3e97z5vNKrUe24GysCSCg@mail.gmail.com>
 <mailman.7619.1393815421.18130.python-list@python.org>
 <roy-759EB5.08411003032014@news.panix.com>
 <mailman.7640.1393854948.18130.python-list@python.org>
Message-ID: <5314b1ed$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 00:55:45 +1100, Chris Angelico wrote:

> But it's an attack vector that MUST be considered, which is why I never
> tell the truth in any "secret question / secret answer" boxes. Why some
> sites think "mother's maiden name" is at all safe is beyond my
> comprehension. And that's not counting the ones that I can't answer
> because I can't find the "NaN" key on my keyboard, like "Surname of
> first girlfriend". *twiddle thumbs*

If you lie to these secret questions -- and I strongly recommend that you 
do -- you should record the answers somewhere so you can retrieve them 
later, long after you've forgotten whether the name of your first pet was 
Obama bin Bush or Tarzan the King of the Desert. Trust me on this, you 
will need them.

The missus has a Yahoo account, and being paranoid even by my standards 
for keeping her web presence completely separate from her real life, she 
invented fake answers to the secret questions like Your Birthday. (As you 
should. It is my opinion that lying to big faceless corporations is not a 
sin, but a duty. They are not on your side, and the more they know about 
you the more they will abuse the knowledge.) So fast forward a few 
months, and the Yahoos at Yahoo put through another bloody round of 
bloody so-called improvements that break everything in sight, including 
people's passwords. So She Who Must Be Obeyed resets her password, except 
now it's *permanently broken* -- no matter how many times she resets her 
password, Yahoo will let her log in *once* then the next time claim the 
password is invalid. 

And then a week or two ago, Yahoo added another piece of broken security 
theatre, and ask you to answer one of those secret questions before 
they'll reset your password. So now SWMBO is locked out of her account 
because she can't remember what she used.

Mind you, Yahoo is rapidly going from Worse to Even Worse, so it was only 
a matter of time before she would have dumped them for good. Still, it's 
annoying -- it's like having your identity stolen by a hermit on some 
mountain top who doesn't do anything with it, except prevent you from 
using it.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From harrismh777 at gmail.com  Mon Mar  3 11:52:55 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 08:52:55 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <mailman.7650.1393865081.18130.python-list@python.org>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <mailman.7638.1393853709.18130.python-list@python.org>
 <466dcd2a-4198-47ac-9797-d4c993e03d61@googlegroups.com>
 <mailman.7650.1393865081.18130.python-list@python.org>
Message-ID: <fbea7748-606c-4a40-8475-13cd74acbe25@googlegroups.com>

On Monday, March 3, 2014 10:44:16 AM UTC-6, Oscar Benjamin wrote:

> Is it on PyPI though? I was referring to a PyPI name so that people
> could install it with "pip install pdeclib" 
> Oscar

hi Oscar, I'm sorry, I completely missed the point of your question. No its not on PyPI, but I don't mind putting it there. Are there special instructions, or is it fairly straight-forward?

marcus


From xpysol at gmail.com  Mon Mar  3 12:23:13 2014
From: xpysol at gmail.com (Wolfgang Maier)
Date: Mon, 3 Mar 2014 09:23:13 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
Message-ID: <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>

Am Montag, 3. M?rz 2014 12:34:30 UTC+1 schrieb Mark H. Harris:
> hi folks,
> 
> 
> 
> Python Decimal Library dmath.py v0.3 Released
> 
> 
> 
> https://code.google.com/p/pythondecimallibrary/
> 
> 
> 
> This code provides the C accelerated decimal module with 
> 
> scientific/transcendental functions for arbitrary precision. 
> 
> I have also included pilib.py which is a PI library of historic
> 
> algorithms for generating PI, which uses dmath.py. 
> 
> 
> 
> I wish to thank Oscar, Wolfgang, Steven, Chris (and others)
> 
> for the help you gave me understanding decimal, particularly
> 
> format, rounding, and context managers. 
> 

Hi Marcus and thanks for the acknowledgement.
Here's one more suggestion for your code.
Your current implementation of fact() for calculating factorials has nothing to offer that isn't provided by math.factorial. Since this is all about Decimal calculations, shouldn't you modify it to something like:

def fact(x):
    """ fact(x)    factorial    {x} int x > 0        

            (x must be integral)
    """    
    return +Decimal(math.factorial(x))

to make it return a Decimal rounded to context precision?


From steve+comp.lang.python at pearwood.info  Mon Mar  3 12:27:51 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 03 Mar 2014 17:27:51 GMT
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
Message-ID: <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 02:01:47 +1100, Chris Angelico wrote:

> This is why it's tricky to put rules in based on type inference. The
> programmer's intent isn't in the picture. 

Of course it is. If I assign 23 to variable x, that signals my intent to 
assign an int to x. By Occam's razor, it is reasonable to extrapolate 
that intent to mean "x is an int", rather than "an int, or a list" or "an 
odd int larger than 7 but smaller than 25", or "any int except 13". Type 
inference picks the type which involves the fewest additional 
assumptions. The programmer can always over-ride the type inference by 
explicitly stating the type.

It works really well in practice, because most of the time you don't need 
a lot of type dynamism. Or even any.

Think about the sort of type declarations you have to do in (say) Pascal, 
and consider how stupid the compiler must be:

function add_one(x: integer):integer;
  begin
    add_one := x+1;
  end;

Given that x is an integer, and that you add 1 (also an integer) to it, 
is it really necessary to tell the compiler that add_one returns an 
integer? What else could the output type be?

This was state of the art back in 1970, but these days, if the compiler 
cannot *at least* infer the type of the return result of a function given 
the argument types, the static type system is too dumb to bother with. A 
good static type system can even detect infinite loops at compile time:

http://perl.plover.com/yak/typing/notes.html

This is not cutting edge technology: ML dates back to the 1990s, if not 
older.


> If Python ever acquires that
> kind of restriction ("here's a list that can contain only this type /
> these types of object"), I would hope that it's left up to the
> programmer, not the compiler, to stipulate.

That's not type inference. That's ancient and annoying obligatory type 
declarations as used by ancient languages with primitive type systems, 
like Pascal and C.


> That's how it is with Pike
> (if you just say "array", it can take anything), and that's the only way
> to be sure the programmer doesn't have to fight the language.

To be sure, any form of static typing is going to restrict what you can 
do. This isn't intended to imply that static typing is better than 
dynamic typing. But if you have static typing, there's *no point* to it 
if the type system cannot detect bugs, and having to declare types is 
like having to calculate your own GOTO addresses. With a good type system 
like ML or Haskell have, you're not fighting the compiler, *every* type 
error you get is a real, actual bug in your code.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Mon Mar  3 12:41:43 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 03 Mar 2014 17:41:43 GMT
Subject: Password validation security issue
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <CALwzidmTaS5QgeQcAbuU8T5e4Hp=u3e97z5vNKrUe24GysCSCg@mail.gmail.com>
 <mailman.7619.1393815421.18130.python-list@python.org>
 <roy-759EB5.08411003032014@news.panix.com>
Message-ID: <5314bed6$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Mon, 03 Mar 2014 08:41:10 -0500, Roy Smith wrote:

> In article <mailman.7619.1393815421.18130.python-list at python.org>,
>  Chris Angelico <rosuav at gmail.com> wrote:
> 
>> The greatest threats these days are from the network, not from someone
>> physically walking into an office. (That said, though, the low-hanging
>> fruit from walking into an office can be *extremely* tempting. Pulling
>> off a basic password leech off sticky notes is often so easy that it
>> can be done as a visitor, or at least as a pizza deliveryman.)
> 
> Doesn't even require physical presence.  With the ubiquity of various
> video chat applications, as long as the sticky note is in the field of
> view of the camera, you've leaked the password.  With the right
> lighting, I wouldn't be surprised if you could pick up the reflection of
> a sticky note in somebody's eyeglasses.

Let's see now... 

- one in a ten thousand chance that somebody will hack my account because 
it has a weak password; versus

- one in a thousand million chance that somebody will view my strong 
password reflected in my glasses and be able to identify what account 
name for which system it goes with, and be the sort of opportunistic 
black-hat who will use it to break into my account.

Nobody is saying that writing passwords down is secure against every and 
any possible attack. (When the Secret Police smash your door down at 3am, 
you probably won't have time to eat the passwords, even if you remembered 
to print them on rice paper instead of a sticky note.) The concept is 
that writing down strong passwords is preferable to remembering weak 
passwords given the typical threats most people are exposed to.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Mon Mar  3 13:37:27 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 05:37:27 +1100
Subject: Functional programming
In-Reply-To: <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmr5Kosg5gDT6xFbmNZNYRN+r=QbCmbCbJLSqcjzm4N7yA@mail.gmail.com>

On Tue, Mar 4, 2014 at 4:27 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Tue, 04 Mar 2014 02:01:47 +1100, Chris Angelico wrote:
>
>> This is why it's tricky to put rules in based on type inference. The
>> programmer's intent isn't in the picture.
>
> Of course it is. If I assign 23 to variable x, that signals my intent to
> assign an int to x. By Occam's razor, it is reasonable to extrapolate
> that intent to mean "x is an int", rather than "an int, or a list" or "an
> odd int larger than 7 but smaller than 25", or "any int except 13". Type
> inference picks the type which involves the fewest additional
> assumptions. The programmer can always over-ride the type inference by
> explicitly stating the type.

Yes, and that's fine for most purposes. The problem isn't the
inference, the problem is when rules are created based on that kind of
guess - when the programmer's subsequent actions are governed by a
guess the compiler takes.

x = 23 # Compiler goes: Okay, x takes ints.
x += 5 # Compiler: No prob, int += int --> int
x = str(x) # Compiler: NO WAY! str(int) --> str, not allowed!

It's fine and correct to infer that x is an int, x is an int, x is a
str. It's *not* okay to make the third line a SyntaxError because you
just put a str into an int variable.

>> If Python ever acquires that
>> kind of restriction ("here's a list that can contain only this type /
>> these types of object"), I would hope that it's left up to the
>> programmer, not the compiler, to stipulate.
>
> That's not type inference. That's ancient and annoying obligatory type
> declarations as used by ancient languages with primitive type systems,
> like Pascal and C.

And that's exactly what Haskell apparently has, with homogeneous lists
and no easy way to say that it can take more types.

Python's handling is: A list can hold anything.

Pike's handling is: An array can hold anything, unless you specify
otherwise. You can specify whatever you can code:
array(int(1000..2000) | string('a'..'z') | float) foo = ({1234,
"abcd", 1.2});

Haskell's handling apparently is: A list/array can hold one thing and
one thing only. That 'thing' can be a union, but then you need to be
REALLY explicit about which side is which. It's not possible to
sub-specify a type (like the "string('a'..'x')" type in Pike that will
take only strings with nothing but the first 24 lower-case letters -
not that I've ever needed that), but the compiler can work out
everything else.

The way I see it, Python's form is fully dynamic and open, Pike's is
fully dynamic and the programmer's allowed to explicitly close things,
and Haskell's is rigidly tight. That's not to say that tight is a bad
thing (it's probably good for learning under), but personally, I'd
rather have the freedom.

ChrisA


From tjreedy at udel.edu  Mon Mar  3 13:35:37 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 03 Mar 2014 13:35:37 -0500
Subject: Origin of 'self'
In-Reply-To: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
Message-ID: <lf2i1m$3i1$2@ger.gmane.org>

On 3/3/2014 1:16 AM, Westley Mart?nez wrote:
> I understand that in an object method the first argument in the
> object itself, called self.  However, it doesn't have to be called
> self, and can be called anything.  So my question is why is it called
> self and not this like from C++ and Java.  It's kind of a silly
> question, but one that I'm curious about nevertheless.

Three responses and I learned or had something pointed out in each. That 
is a better track record than most threads.

-- 
Terry Jan Reedy




From rosuav at gmail.com  Mon Mar  3 13:46:48 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 05:46:48 +1100
Subject: Password validation security issue
In-Reply-To: <5314b1ed$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <09f43567-779e-4d01-8621-c4eb36354d99@googlegroups.com>
 <CAPTjJmqCTLqXgmHMm2QGYJB1MmYEnhMV3OGe0jPc_UOoUQ9gQA@mail.gmail.com>
 <let920$fmn$1@ger.gmane.org>
 <CAPTjJmq0MYQugUnsL52ZN0um=V3iABHmM4+vsffD=+2YV7t=MA@mail.gmail.com>
 <letdt5$1g3$1@ger.gmane.org>
 <CAPTjJmra0AjHYjk3G+2mSgsewpX0qcmcKpQtqnebHXsQfT2YqQ@mail.gmail.com>
 <mailman.7592.1393788339.18130.python-list@python.org>
 <roy-5B94F1.15010902032014@news.panix.com>
 <5313d7fe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <CALwzidmTaS5QgeQcAbuU8T5e4Hp=u3e97z5vNKrUe24GysCSCg@mail.gmail.com>
 <mailman.7619.1393815421.18130.python-list@python.org>
 <roy-759EB5.08411003032014@news.panix.com>
 <mailman.7640.1393854948.18130.python-list@python.org>
 <5314b1ed$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmrSHkKkuqYWHPC-WStHaEVFgn7JuM28DDBojBSxRutOhQ@mail.gmail.com>

On Tue, Mar 4, 2014 at 3:46 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Tue, 04 Mar 2014 00:55:45 +1100, Chris Angelico wrote:
>
>> But it's an attack vector that MUST be considered, which is why I never
>> tell the truth in any "secret question / secret answer" boxes. Why some
>> sites think "mother's maiden name" is at all safe is beyond my
>> comprehension. And that's not counting the ones that I can't answer
>> because I can't find the "NaN" key on my keyboard, like "Surname of
>> first girlfriend". *twiddle thumbs*
>
> If you lie to these secret questions -- and I strongly recommend that you
> do -- you should record the answers somewhere so you can retrieve them
> later, long after you've forgotten whether the name of your first pet was
> Obama bin Bush or Tarzan the King of the Desert. Trust me on this, you
> will need them.
>
> The missus has a Yahoo account, and being paranoid even by my standards
> for keeping her web presence completely separate from her real life, she
> invented fake answers to the secret questions like Your Birthday. (As you
> should. It is my opinion that lying to big faceless corporations is not a
> sin, but a duty. They are not on your side, and the more they know about
> you the more they will abuse the knowledge.)

I've followed this for a long time. If anything asks for my date of
birth and appears to be just verifying that I'm at least 13 years old,
I'll say Jan 1st in some year that's vaguely near my year of birth.
(This is largely because the drop down combo boxes usually already say
Jan 1st, and it's pointlessly tedious to aim for my exact year, much
less the day within that.) My brother's new wife (married last Nov)
didn't understand this about me when I was helping her port her mobile
phone onto the family account. The system asks me for a date of birth,
and I turn to her and say, "What date of birth did you use?" - and she
looks at me funny, not understanding why I don't already know what to
fill in. But for all I know, she could have set up her mobile account
with a DOB of 1912/6/23 in commemoration of cryptography.

But yes, on the (frequent) occasions when I lie through my teeth, I
usually record my answers as separate passwords.

ChrisA


From tjreedy at udel.edu  Mon Mar  3 13:48:39 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 03 Mar 2014 13:48:39 -0500
Subject: Reference
In-Reply-To: <53144e8d$0$2149$426a74cc@news.free.fr>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
Message-ID: <lf2iq4$fad$1@ger.gmane.org>

On 3/3/2014 4:42 AM, ast wrote:

> Consider following code:
>
>>>> A=7
>>>> B=7
>>>> A is B

The 'is' operator has three uses, two intended and one not. In 
production code, 'is' tests that an object *is* a particular singular 
object, such as None or a sentinel instance of class object. In test 
code, 'is' can also be used to test details of a particular 
implementation, such as pre-allocation of small ints. New python 
programmers also use it to confuse themselves.

-- 
Terry Jan Reedy



From breamoreboy at yahoo.co.uk  Mon Mar  3 14:47:36 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 03 Mar 2014 19:47:36 +0000
Subject: 3.4rc2 and pip on windows
In-Reply-To: <lf0h42$l88$2@ger.gmane.org>
References: <lf0ge3$fbv$1@ger.gmane.org> <lf0h42$l88$2@ger.gmane.org>
Message-ID: <lf2m8g$ouv$1@ger.gmane.org>

On 03/03/2014 00:07, Terry Reedy wrote:
> On 3/2/2014 6:55 PM, Mark Lawrence wrote:
>> Trying to install pyttsx, it doesn't strike me as very clever that, as
>> seen below, you get "Successfully installed pyttsx" despite the syntax
>> errors and you can't actually do an import.
>>
>> c:\Users\Mark\CrossCode>c:\Python34\Scripts\pip3.4.exe install pyttsx
>> Downloading/unpacking pyttsx
>>    Downloading pyttsx-1.1.tar.gz
>>    Running setup.py
>> (path:C:\Users\Mark\AppData\Local\Temp\pip_build_Mark\pyttsx\setup.py)
>> egg_info for package pyttsx
>>
>> Installing collected packages: pyttsx
>>    Running setup.py install for pyttsx
>>        File "C:\Python34\Lib\site-packages\pyttsx\driver.py", line 105
>>          except Exception, e:
>>                          ^
>>      SyntaxError: invalid syntax
>>
>> [other syntax errors snipped]
>>
>> Successfully installed pyttsx
>
> A bug it seems to me.
>
>> Cleaning up...
>>
>> c:\Users\Mark\CrossCode>py -3.4
>> Python 3.4.0rc2 (v3.4.0rc2:a300712ed38c, Feb 23 2014, 10:49:04) [MSC
>> v.1600 32 bit (Intel)] on win32
>> Type "help", "copyright", "credits" or "license" for more information.
>>  >>> import pyttsx
>> Traceback (most recent call last):
>>    File "<stdin>", line 1, in <module>
>>    File "C:\Python34\lib\site-packages\pyttsx\__init__.py", line 18, in
>> <module>
>>      from engine import Engine
>>
>> I've looked at pyttsx in my 3.3 site-packages and it appears that I've
>> manually run 2to3.  Is this something that could be done automatically
>> by pip?  Your thoughts please, ladies and gentlemen.
>
> I should hope so.
>

FTR I raised this as http://bugs.python.org/issue20846 and it was closed 
11 minutes after I raised it.  I won't say anything else as I'm 
extremely tired and irritable and might well regret it later.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From harrismh777 at gmail.com  Mon Mar  3 15:03:19 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 12:03:19 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>
Message-ID: <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>

On Monday, March 3, 2014 11:23:13 AM UTC-6, Wolfgang Maier wrote:

> def fact(x):
>     """ fact(x)    factorial    {x} int x > 0        
>
>     return +Decimal(math.factorial(x))

> to make it return a Decimal rounded to context precision?

hi Wolfgang,  I'm not sure.  We're doing some things with very large factorials where (existentially) we want to know how many zeros are coming up and the end of the very large number (thousands of digits) and 2) what are the last significant figures (say twenty of them) that are just before the zero chain.
What I don't want is for the Decimal module to overflow (didn't know it would do that), and we don't want the number rounded in scientific notation at some number of places. We want to actually see the digits; all of them.
Python will do multiplications til the proverbial cows come home; well, as long as you don't try it recursively --- killing the recursive depth. Decimal has some limits internally which I still do not understand (and I have been looking at the doc and playing with it for hours). If I want to build a BIGNUM int in memory only the memory should limit what can be built, not some arbitrary limit inside Decimal.
Does any of this make sense?  and 2) can you help me understand the overflow in Decimal a little bit better. I know you're a busy guy, maybe you just know a link /

Thanks much.


From harrismh777 at gmail.com  Mon Mar  3 15:10:22 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 12:10:22 -0800 (PST)
Subject: pip and distutils2-1.0a4
Message-ID: <248fe774-aed4-4a59-afac-e746e2110dd7@googlegroups.com>

hi folks,

I am having a fit with pip this afternoon.  I finally
got pip installed on this system from a binary 
blob (what nightmare, talk about 1987). Anyway,
pip is installed, but when I go to PyPI to pull 
down distutils is gives a message that no such
package exists.   I feel like Obeewan;  "if the archive
computer says your planet is not there, it simply
does not exist".
Can somebody tell me what is the best way to get
distutils downloaded to this system?
Thanks in advance.
Somewhere I heard a rumor that distutils is preloaded
with Py3.3.x /  is this True?  like, I might already have 
it??
thanks again
marcus


From donarb at nwlink.com  Mon Mar  3 15:22:48 2014
From: donarb at nwlink.com (donarb)
Date: Mon, 3 Mar 2014 12:22:48 -0800 (PST)
Subject: modification time in Python - Django: datetime != datetime :-(
In-Reply-To: <mailman.7646.1393856904.18130.python-list@python.org>
References: <20140303133541.66fccbbb@lia.custard.shrl.nl>
 <CAPTjJmrp9Ca5zyfo75NKcX_ik0Qi4kOcjhhY6EEWKQ-xJx7KQg@mail.gmail.com>
 <mailman.7646.1393856904.18130.python-list@python.org>
Message-ID: <04659633-e14e-4d5b-90f2-93af04f056be@googlegroups.com>

On Monday, March 3, 2014 6:28:21 AM UTC-8, Jaap van Wingerde wrote:
> Op <Tue, 4 Mar 2014 01:08:52 +1100> schreef Chris Angelico <rosuav at gmail.com> in bericht <CAPTjJmrp9Ca5zyfo75NKcX_ik0Qi4kOcjhhY6EEWKQ-xJx7KQg at mail.gmail.com>:
> 
> > See if ls is actually giving you ctime rather than mtime - compare the
> > results if you ask for os.path.getctime.
> 
> jaap at liakoster:~$ python
> Python 2.7.3 (default, Jan  2 2013, 13:56:14) 
> [GCC 4.7.2] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import os, time
> >>> from time import gmtime
> >>> time.strftime('%Y-%m-%dT%H:%m:%SZ',gmtime(os.path.getmtime('/var/django/test2/art/templates/art_index.html')))
> '2014-03-02T19:03:55Z'
> >>> time.strftime('%Y-%m-%dT%H:%m:%SZ',gmtime(os.path.getctime('/var/django/test2/art/templates/art_index.html')))
> '2014-03-02T19:03:55Z'
> >>> quit()
> jaap at liakoster:~$ ls --full-time /var/django/test2/art/templates/art_index.html
> -rwxrwx--- 1 lia www-data 2456 2014-03-02 19:16:55.568139590 +0000 /var/django/test2/art/templates/art_index.html
> jaap at liakoster:~$ 
> 
> ls is giving me the modified time.

You're using the months format '%m' when you should be using minutes '%M'.


From breamoreboy at yahoo.co.uk  Mon Mar  3 15:53:00 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 03 Mar 2014 20:53:00 +0000
Subject: pip and distutils2-1.0a4
In-Reply-To: <248fe774-aed4-4a59-afac-e746e2110dd7@googlegroups.com>
References: <248fe774-aed4-4a59-afac-e746e2110dd7@googlegroups.com>
Message-ID: <lf2q33$9el$1@ger.gmane.org>

On 03/03/2014 20:10, Mark H. Harris wrote:
> hi folks,
>
> I am having a fit with pip this afternoon.  I finally
> got pip installed on this system from a binary
> blob (what nightmare, talk about 1987). Anyway,
> pip is installed, but when I go to PyPI to pull
> down distutils is gives a message that no such
> package exists.   I feel like Obeewan;  "if the archive
> computer says your planet is not there, it simply
> does not exist".
> Can somebody tell me what is the best way to get
> distutils downloaded to this system?
> Thanks in advance.
> Somewhere I heard a rumor that distutils is preloaded
> with Py3.3.x /  is this True?  like, I might already have
> it??
> thanks again
> marcus
>

distutils has been part of the standard library for years.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From ben+python at benfinney.id.au  Mon Mar  3 16:06:21 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 04 Mar 2014 08:06:21 +1100
Subject: modification time in Python - Django: datetime != datetime :-(
References: <20140303133541.66fccbbb@lia.custard.shrl.nl>
Message-ID: <85txbfhu0i.fsf@benfinney.id.au>

Jaap van Wingerde <mailinglists at vanwingerde.nl> writes:

> >>> time.strftime('%Y-%m-%dT%H:%m:%SZ',gmtime(os.path.getmtime('/var/django/test2/art/templates/art_index.html')))  
> '2014-03-02T19:03:55Z'
> >>> quit()  
> jaap at liakoster:~$ ls --full-time /var/django/test2/art/templates/art_index.html
> -rwxrwx--- 1 lia www-data 2456 2014-03-02 19:16:55.568139590 +0000 /var/django/test2/art/templates/art_index.html
> jaap at liakoster:~$ 
> ...
>
> ls gives the right modification time. What is wrong?

You're using ?gmtime? to display the Python datetime value, but ?ls?
will display the time in the local timezone. Do you have a strange
timezone set?

What value does the Python datetime value show in the local timezone?
How does that compare to the time shown by ?ls??

-- 
 \              ?When cryptography is outlawed, bayl bhgynjf jvyy unir |
  `\                                              cevinpl.? ?Anonymous |
_o__)                                                                  |
Ben Finney



From rosuav at gmail.com  Mon Mar  3 16:11:46 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 08:11:46 +1100
Subject: modification time in Python - Django: datetime != datetime :-(
In-Reply-To: <04659633-e14e-4d5b-90f2-93af04f056be@googlegroups.com>
References: <20140303133541.66fccbbb@lia.custard.shrl.nl>
 <CAPTjJmrp9Ca5zyfo75NKcX_ik0Qi4kOcjhhY6EEWKQ-xJx7KQg@mail.gmail.com>
 <mailman.7646.1393856904.18130.python-list@python.org>
 <04659633-e14e-4d5b-90f2-93af04f056be@googlegroups.com>
Message-ID: <CAPTjJmrz-oq-YLZ_0=jHgj9B1y4s_6bZfN52XMn6Xw10TXE2FQ@mail.gmail.com>

On Tue, Mar 4, 2014 at 7:22 AM, donarb <donarb at nwlink.com> wrote:
> You're using the months format '%m' when you should be using minutes '%M'.

Heh! I didn't even notice that. When I tested it, I didn't use
strftime at all, just looked at gmtime's output.

ChrisA


From ben+python at benfinney.id.au  Mon Mar  3 16:10:21 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 04 Mar 2014 08:10:21 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
Message-ID: <85ppm3httu.fsf@benfinney.id.au>

Rustom Mody <rustompmody at gmail.com> writes:

> Short answer: Avoid using 'is'. 

This is bad advice in a Python forum.

The ?is? operator is commonly used in Python, so please don't advise
against it in an unqualified ?short answer?.

> Long answer: http://www.beyondwilber.ca/healing-thinking/non-identity-korzybski.html

Interesting, but mostly a distraction for the querent here.

Short answer: Use ?use? any time you need to compare object identity.
You usually do not need to compare object identity.

-- 
 \        ?Some people, when confronted with a problem, think ?I know, |
  `\       I'll use regular expressions?. Now they have two problems.? |
_o__)                           ?Jamie Zawinski, in alt.religion.emacs |
Ben Finney



From harrismh777 at gmail.com  Mon Mar  3 16:18:37 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 13:18:37 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>
 <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>
Message-ID: <3d7636ab-7544-46db-a1b1-113967dc28d6@googlegroups.com>

On Monday, March 3, 2014 2:03:19 PM UTC-6, Mark H. Harris wrote:
> On Monday, March 3, 2014 11:23:13 AM UTC-6, Wolfgang Maier wrote:

Wolfgang,  answer is not so much, in fact, not at all. 
But it is an interesting question for me; where I am 
continuing to learn the limits of Decimal, and the 
decimal context. I don't need rounding for integer 
multiplication, of course. 

I am interested in arbitrary limits, like emax, for instance. 
The doc is a little ambiguous. Is emax the max exponent, 
and if so, is 999999999 the limit, or is that the default 
context value which might be bumped up? 
If so, why have a limit on the emin & emax values?
I'm playing with it. Shouldn't a Decimal value 
be able to continue to grow to the limit of memory if we 
wanted to be silly about it? According to the doc 'clamping'
occurs if the exponent falls outside the range of emin &  
emax (what is overflow vs clamping ?) if the significant digits
are allowed to grow and grow? Well, the doc then states that
overflow occurs if we blow past the emax exponent value?
What is the difference between overflow and clamping? Am
I able to set emin & emax arbitrarily high or low? 

I have discovered just by playing with integer multiplication 
that those BIGNUMS don't seem to have a physical limit. Of 
course there isn't a decimal to keep track of, and they can 
just grow and grow; wouldn't want to make a Decimal from 
one of those, other than it is interesting to me as I'm trying
to understand Decimal floating point.  

marcus




From python.list at tim.thechases.com  Mon Mar  3 16:24:38 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Mon, 3 Mar 2014 15:24:38 -0600
Subject: Reference
In-Reply-To: <85ppm3httu.fsf@benfinney.id.au>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au>
Message-ID: <20140303152438.3454049a@bigbox.christie.dr>

On 2014-03-04 08:10, Ben Finney wrote:
> > Long answer:
> > http://www.beyondwilber.ca/healing-thinking/non-identity-korzybski.html  
> 
> Interesting, but mostly a distraction for the querent here.
> 
> Short answer: Use ?use? any time you need to compare object
> identity. You usually do not need to compare object identity.

I think there use something wrong with that sentence...unless there
usen't. ;-)

-tkc




From harrismh777 at gmail.com  Mon Mar  3 16:20:50 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 13:20:50 -0800 (PST)
Subject: pip and distutils2-1.0a4
In-Reply-To: <mailman.7656.1393880003.18130.python-list@python.org>
References: <248fe774-aed4-4a59-afac-e746e2110dd7@googlegroups.com>
 <mailman.7656.1393880003.18130.python-list@python.org>
Message-ID: <acf1abdd-b0e7-4d4f-ab76-18c2998b8742@googlegroups.com>

On Monday, March 3, 2014 2:53:00 PM UTC-6, Mark Lawrence wrote:

> distutils has been part of the standard library for years.

hi Mark, that's fabulous, why can't I import it? Because I'm doing 
something wrong of course.   :)

marcus


From ben+python at benfinney.id.au  Mon Mar  3 16:31:23 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 04 Mar 2014 08:31:23 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au>
 <20140303152438.3454049a@bigbox.christie.dr>
Message-ID: <85lhwrhsus.fsf@benfinney.id.au>

Tim Chase <python.list at tim.thechases.com> writes:

> On 2014-03-04 08:10, Ben Finney wrote:
> > Short answer: Use ?use? any time you need to compare object
> > identity. You usually do not need to compare object identity.

Damn it, a snappy response marred by a typo.

> I think there use something wrong with that sentence...unless there
> usen't. ;-)

That use correct. Thanks, Tim :-)

-- 
 \      ?Software patents provide one more means of controlling access |
  `\      to information. They are the tool of choice for the internet |
_o__)                                     highwayman.? ?Anthony Taylor |
Ben Finney



From robert.kern at gmail.com  Mon Mar  3 16:32:43 2014
From: robert.kern at gmail.com (Robert Kern)
Date: Mon, 03 Mar 2014 21:32:43 +0000
Subject: pip and distutils2-1.0a4
In-Reply-To: <acf1abdd-b0e7-4d4f-ab76-18c2998b8742@googlegroups.com>
References: <248fe774-aed4-4a59-afac-e746e2110dd7@googlegroups.com>
 <mailman.7656.1393880003.18130.python-list@python.org>
 <acf1abdd-b0e7-4d4f-ab76-18c2998b8742@googlegroups.com>
Message-ID: <lf2sdd$3qn$1@ger.gmane.org>

On 2014-03-03 21:20, Mark H. Harris wrote:
> On Monday, March 3, 2014 2:53:00 PM UTC-6, Mark Lawrence wrote:
>
>> distutils has been part of the standard library for years.
>
> hi Mark, that's fabulous, why can't I import it? Because I'm doing
> something wrong of course.   :)

Probably. If you want us to help, you need to show us what you tried, tell us 
what results you expected, and copy-paste the output that you got.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco



From breamoreboy at yahoo.co.uk  Mon Mar  3 16:35:56 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 03 Mar 2014 21:35:56 +0000
Subject: Reference
In-Reply-To: <85ppm3httu.fsf@benfinney.id.au>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au>
Message-ID: <lf2sjk$7d4$1@ger.gmane.org>

On 03/03/2014 21:10, Ben Finney wrote:
> Rustom Mody <rustompmody at gmail.com> writes:
>
>> Short answer: Avoid using 'is'.
>
> This is bad advice in a Python forum.
>
> The ?is? operator is commonly used in Python, so please don't advise
> against it in an unqualified ?short answer?.
>
>> Long answer: http://www.beyondwilber.ca/healing-thinking/non-identity-korzybski.html
>
> Interesting, but mostly a distraction for the querent here.
>
> Short answer: Use ?use? any time you need to compare object identity.
> You usually do not need to compare object identity.
>

That last paragraph is as clear as mud.

I'd just like to know why people are so obsessed with identities, I've 
never thought to use them in 10+ years of writing Python.  Do I use the 
KISS principle too often?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From harrismh777 at gmail.com  Mon Mar  3 16:37:22 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 13:37:22 -0800 (PST)
Subject: pip and distutils2-1.0a4
In-Reply-To: <mailman.7662.1393882380.18130.python-list@python.org>
References: <248fe774-aed4-4a59-afac-e746e2110dd7@googlegroups.com>
 <mailman.7656.1393880003.18130.python-list@python.org>
 <acf1abdd-b0e7-4d4f-ab76-18c2998b8742@googlegroups.com>
 <mailman.7662.1393882380.18130.python-list@python.org>
Message-ID: <31feb451-7fb6-48a6-9986-bddce69c4991@googlegroups.com>

On Monday, March 3, 2014 3:32:43 PM UTC-6, Robert Kern wrote:

> Probably. If you want us to help, you need to show us what you tried, tell us 
> what results you expected, and copy-paste the output that you got.

> Robert Kern

hi Robert,  well, I finally came up with trying to find setup().  Its a part of 
distutils.core. So, I tried:

from distutils.core import setup
from distutils import *

Then I tried to run setup() --help-commands and python3 crashed.

What did I do wrong?   running Py3.3.4

Thanks, marcus


From bc at freeuk.com  Mon Mar  3 16:43:29 2014
From: bc at freeuk.com (BartC)
Date: Mon, 3 Mar 2014 21:43:29 -0000
Subject: why indentation should be part of the syntax
In-Reply-To: <mailman.7568.1393756930.18130.python-list@python.org>
References: <mailman.7568.1393756930.18130.python-list@python.org>
Message-ID: <tI6Ru.12701$if6.3366@fx07.am4>



"Stefan Behnel" <stefan_ml at behnel.de> wrote in message 
news:mailman.7568.1393756930.18130.python-list at python.org...
> Haven't seen any mention of it on this list yet, but since it's such an
> obvious flaw in quite a number of programming languages, here's a good
> article on the recent security bug in iOS, which was due to accidentally
> duplicated code not actually being as indented as it looked:
>
> https://www.imperialviolet.org/2014/02/22/applebug.html

Indentation is actually a little more fragile than block-delimited source 
code. (Press Delete inadvertently so that a tab disappears, and the code 
might still be valid, but is now wrong.)

Perhaps indentation /and/ block-delimiting would be more robust.

(And the link shows a bad example: the error should have been picked up 
anyway, but the language not only doesn't require formal indentation, but it 
uses optional block ({}) delimiters, another source of errors. Having an 
undifferentiated } to close all kinds of blocks doesn't help either.

-- 
Bartc 



From roy at panix.com  Mon Mar  3 16:44:31 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 03 Mar 2014 16:44:31 -0500
Subject: pip and distutils2-1.0a4
References: <248fe774-aed4-4a59-afac-e746e2110dd7@googlegroups.com>
 <mailman.7656.1393880003.18130.python-list@python.org>
 <acf1abdd-b0e7-4d4f-ab76-18c2998b8742@googlegroups.com>
 <mailman.7662.1393882380.18130.python-list@python.org>
 <31feb451-7fb6-48a6-9986-bddce69c4991@googlegroups.com>
Message-ID: <roy-A6DF0A.16443103032014@news.panix.com>

In article <31feb451-7fb6-48a6-9986-bddce69c4991 at googlegroups.com>,
 "Mark H. Harris" <harrismh777 at gmail.com> wrote:

> On Monday, March 3, 2014 3:32:43 PM UTC-6, Robert Kern wrote:
> 
> > Probably. If you want us to help, you need to show us what you tried, tell 
> > us 
> > what results you expected, and copy-paste the output that you got.
> 
> > Robert Kern
> 
> hi Robert,  well, I finally came up with trying to find setup().  Its a part 
> of 
> distutils.core. So, I tried:
> 
> from distutils.core import setup
> from distutils import *
> 
> Then I tried to run setup() --help-commands and python3 crashed.
> 
> What did I do wrong?   running Py3.3.4
> 
> Thanks, marcus

General advice to everybody who asks questions.  Please don't *describe* 
what you did.  *Show* us what you did.  Run your commands in a terminal 
window and then copy-and-paste everything that you typed and everything 
that got printed.


From python.list at tim.thechases.com  Mon Mar  3 16:51:12 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Mon, 3 Mar 2014 15:51:12 -0600
Subject: Reference
In-Reply-To: <lf2sjk$7d4$1@ger.gmane.org>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
Message-ID: <20140303155112.46e34ff8@bigbox.christie.dr>

On 2014-03-03 21:35, Mark Lawrence wrote:
> I'd just like to know why people are so obsessed with identities,
> I've never thought to use them in 10+ years of writing Python.  Do
> I use the KISS principle too often?

There are a couple use-cases I've encountered where "is" matters:

1) the most popular:

  if foo is None:
    do_stuff()

2) sentinels (which are effectively non-None None values)

  SENTINEL = object()

  def myfuntion(value=SENTINEL):
    if value is SENTINEL:
      do_something_parameterless()
    else:
      do_something_else(value) # allow for value=None

3) when doing recursion and you want to prevent touching the same
object multiple times, such as what happens when you do

  lst = [1,2,3]
  lst.append(lst)
  print(lst)

and it needs to recognize that the final element of "lst" is one that
it has already seen (as done by identity).


There might be some other use cases, but #1 is a good 95% of my
usage, #2 is a good 4%, and I can only think of once in my Python
career when I've needed to do what is described in #3.

-tkc







From cs at zip.com.au  Mon Mar  3 17:02:07 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Tue, 4 Mar 2014 09:02:07 +1100
Subject: how to get bytes from bytearray without copying
In-Reply-To: <lf1dlq$94o$1@ger.gmane.org>
References: <lf1dlq$94o$1@ger.gmane.org>
Message-ID: <20140303220207.GA29739@cskk.homeip.net>

On 03Mar2014 09:15, Juraj Ivan?i? <juraj.ivancic at gmail.com> wrote:
> On 3.3.2014. 1:44, Cameron Simpson wrote:
> >>ValueError: cannot hash writable memoryview object
> >
> >Have you considered subclassing memoryview and giving the subclass
> >a __hash__ method?
> 
> I have, and then, when I failed to subclass it, I considered doing
> aggregation, and make it behave byte-like. But how to implement the
> overridden __hash__ method? It will still require at least *some*
> redundant copying. And there is the slicing thing... the whole idea
> started to feel like I was performing tonsillectomy through the anal
> cavity.

Write a wrapper class instead and use:

  def __hash__(self):
    return id(self)

Simple and fast. Unless you need slices with the same content to
hash the same (eg storing them as dict keys, or in sets).

And alternative would be a simple hash of the first few bytes in
whatever slice you had.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

Why is it so hard for people to simply leave people alone? But, the answer
comes to me: they are idiots and in a perfect world, I would be permitted to
kill them all.  - Julie Rhodes <jk.rhodes at asacomp.com>


From malaclypse2 at gmail.com  Mon Mar  3 17:02:14 2014
From: malaclypse2 at gmail.com (Jerry Hill)
Date: Mon, 3 Mar 2014 17:02:14 -0500
Subject: Reference
In-Reply-To: <20140303155112.46e34ff8@bigbox.christie.dr>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
Message-ID: <CADwdpyYP1XzcSRq38g4ugED8HEaZN3KOFmQMwXcojnLqQSiwgw@mail.gmail.com>

On Mon, Mar 3, 2014 at 4:51 PM, Tim Chase <python.list at tim.thechases.com> wrote:
> There are a couple use-cases I've encountered where "is" matters:
>
> 1) the most popular:
>
>   if foo is None:
>     do_stuff()

I know this is the one that always comes up, but honestly, I feel like
"is" doesn't matter here.  That code would be just as correct if it
was written as:

if foo == None:
    do_stuff()

The only time it would give you a different result from the "is"
version is if foo was bound to an object that returned True when
compared with None.  And if that were the case, I'm still not
convinced that you can tell from looking at those two lines of code
which one is buggy, except for the fact that there has been 20 years
of custom saying that comparing to None with equality is wrong.

-- 
Jerry


From greg.ewing at canterbury.ac.nz  Mon Mar  3 17:06:31 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Tue, 04 Mar 2014 11:06:31 +1300
Subject: Functional programming
In-Reply-To: <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>	<mailman.7612.1393810048.18130.python-list@python.org>	<4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>	<mailman.7633.1393849247.18130.python-list@python.org>	<3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>	<mailman.7641.1393855219.18130.python-list@python.org>	<216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>	<mailman.7644.1393856584.18130.python-list@python.org>	<0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>	<mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <bnkcn8FphikU1@mid.individual.net>

Steven D'Aprano wrote:
> Given that x is an integer, and that you add 1 (also an integer) to it, 
> is it really necessary to tell the compiler that add_one returns an 
> integer? What else could the output type be?

Just because the compiler *can* infer the return type
doesn't necessarily mean it *should*. When I was playing
around with functional languages, I ended up adopting the
practice of always declaring the types of my functions,
because it helps the *human* reader. (It also helped the
compiler produce comprehensible error messages in the
event of a type error.)

-- 
Greg


From marko at pacujo.net  Mon Mar  3 17:07:45 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 04 Mar 2014 00:07:45 +0200
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au>
 <mailman.7663.1393882574.18130.python-list@python.org>
Message-ID: <87wqgb6imm.fsf@elektro.pacujo.net>

Mark Lawrence <breamoreboy at yahoo.co.uk>:

> I'd just like to know why people are so obsessed with identities, I've
> never thought to use them in 10+ years of writing Python.  Do I use the
> KISS principle too often?

Calmly choosing the right tool for the job is not an obsession.


Marko


From harrismh777 at gmail.com  Mon Mar  3 17:08:37 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 14:08:37 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <3d7636ab-7544-46db-a1b1-113967dc28d6@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>
 <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>
 <3d7636ab-7544-46db-a1b1-113967dc28d6@googlegroups.com>
Message-ID: <3169bb71-472c-4c26-8de2-113e8942df15@googlegroups.com>

On Monday, March 3, 2014 3:18:37 PM UTC-6, Mark H. Harris wrote:

Yeah, you can set Emin & Emax enormously large (or small), can set
off overflow, and set clamping. 

I am needing a small utility (tk?) that will allow the context to be set
manually by the interactive user dynamically (for a particular problem).
Its like, one context doesn't fit all.  Some of the pdeclib funcs will need
to take into account the various signals also. 

The context manger is fabulous, but not for the average user; all the
try block stuff is encapsulated (which makes the coding clean) but it
is not obvious in any way what is happening with __init__() , __enter__()
and __exit__() (although I did find a couple of good articles on the
subject. The 'with localcontext(cts=None) as ctx' is genius, but not
for the average user who just wants to get work done with python.

So, the bottom line is we have this fabulous speedy decimal module
that is nothing short of wonderful for experts, and completely out
of the grasp of average users relatively new to python or with 
limited experience with decimal floating point arithmetic. "They would
like to sing soft and sweet, like the cucumber, but they can't!"

So, we need a complete wrapper around the decimal module (or better
yet we need to make decimal floating point default) so that average 
users may take advantage of precise floating point math without 
having to be experts on decimal floating point arithmetic constraints
in the new high speed module.    :-}

marcus
 


From robert.kern at gmail.com  Mon Mar  3 17:11:44 2014
From: robert.kern at gmail.com (Robert Kern)
Date: Mon, 03 Mar 2014 22:11:44 +0000
Subject: pip and distutils2-1.0a4
In-Reply-To: <31feb451-7fb6-48a6-9986-bddce69c4991@googlegroups.com>
References: <248fe774-aed4-4a59-afac-e746e2110dd7@googlegroups.com>
 <mailman.7656.1393880003.18130.python-list@python.org>
 <acf1abdd-b0e7-4d4f-ab76-18c2998b8742@googlegroups.com>
 <mailman.7662.1393882380.18130.python-list@python.org>
 <31feb451-7fb6-48a6-9986-bddce69c4991@googlegroups.com>
Message-ID: <lf2umi$lj$1@ger.gmane.org>

On 2014-03-03 21:37, Mark H. Harris wrote:
> On Monday, March 3, 2014 3:32:43 PM UTC-6, Robert Kern wrote:
>
>> Probably. If you want us to help, you need to show us what you tried, tell us
>> what results you expected, and copy-paste the output that you got.
>
>> Robert Kern
>
> hi Robert,  well, I finally came up with trying to find setup().  Its a part of
> distutils.core. So, I tried:
>
> from distutils.core import setup
> from distutils import *
>
> Then I tried to run setup() --help-commands and python3 crashed.
>
> What did I do wrong?   running Py3.3.4

You don't run `setup() --help-commands` in the Python interpreter. 
`--help-commands` is a command-line argument to the setup.py script that you 
will write. It is not Python syntax. Please read the documentation.

   http://docs.python.org/3/distutils/index.html

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco



From zachary.ware+pylist at gmail.com  Mon Mar  3 16:48:03 2014
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Mon, 3 Mar 2014 15:48:03 -0600
Subject: 3.4rc2 and pip on windows
In-Reply-To: <lf2m8g$ouv$1@ger.gmane.org>
References: <lf0ge3$fbv$1@ger.gmane.org> <lf0h42$l88$2@ger.gmane.org>
 <lf2m8g$ouv$1@ger.gmane.org>
Message-ID: <CAKJDb-Mo=j=1znZURUNvDN6q20WjmVv-S4O=xMC9mH6BTjy6tQ@mail.gmail.com>

On Mon, Mar 3, 2014 at 1:47 PM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> FTR I raised this as http://bugs.python.org/issue20846 and it was closed 11
> minutes after I raised it.  I won't say anything else as I'm extremely tired
> and irritable and might well regret it later.

Best I can tell, the issue was closed correctly.  It doesn't look like
a Python or Pip bug, it looks like a bug in pyttsx's packaging.  Based
on empirical data [1], Pip does properly take care of running 2to3,
but *only when told to do so*.  Pip can't decide whether it should run
2to3 when it hasn't been told either way, because it's not safe.  It
can't try compiling .py files and running 2to3 if it gets
SyntaxErrors, because what if the SyntaxError is just a SyntaxError,
and not a ThisHasntBeenPortedToPython3Error?  Then 2to3 might blow up,
possibly leaving things in a state that makes the underlying issue
very hard to find.  It can't try importing the installed package,
because what if importing without specific external state in place has
ugly side-effects?  Pip can't safely do anything it's not told to do
with the packages it installs because then responsibility for the fire
in your hard drive could be laid at Pip's feet, not the evil evil
package author who wrote the code that started the fire.

It could be argued that Pip could compile any .py files that it
installs and just start screaming if it gets any SyntaxError, but what
if your package (for some weird reason) relies on .py file with bad
syntax?

I don't think Python itself is involved at all here, and I think Pip
is doing the right thing.  Everything installed successfully into the
right place (since `import pyttsx` did find the package); the fact
that it SyntaxError'd out is on the package author.

My 0.02USD, anyway.

-- 
Zach

[1] `pip install sphinx` from a 3.4 venv


From ben+python at benfinney.id.au  Mon Mar  3 17:17:55 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 04 Mar 2014 09:17:55 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <CADwdpyYP1XzcSRq38g4ugED8HEaZN3KOFmQMwXcojnLqQSiwgw@mail.gmail.com>
Message-ID: <85d2i3hqp8.fsf@benfinney.id.au>

Jerry Hill <malaclypse2 at gmail.com> writes:

> if foo == None:
>     do_stuff()
>
> The only time it would give you a different result from the "is"
> version is if foo was bound to an object that returned True when
> compared with None.

That's right. Python provides this singleton and then recommends you
compare with ?is?, precisely to protect against pathological cases like
a ?return True when compared for equality with None? data type.

Using ?if foo is None? means you don't even have to spend time worrying
about such cases.

> And if that were the case, I'm still not convinced that you can tell
> from looking at those two lines of code which one is buggy, except for
> the fact that there has been 20 years of custom saying that comparing
> to None with equality is wrong.

Yes. And because of that widespread convention, it's much more correct
to compare against None with ?is?.

-- 
 \       ?Always do right. This will gratify some people, and astonish |
  `\                                            the rest.? ?Mark Twain |
_o__)                                                                  |
Ben Finney



From cs at zip.com.au  Mon Mar  3 17:19:26 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Tue, 4 Mar 2014 09:19:26 +1100
Subject: How security holes happen
In-Reply-To: <lf22t1$sgh$1@ger.gmane.org>
References: <lf22t1$sgh$1@ger.gmane.org>
Message-ID: <20140303221926.GA57537@cskk.homeip.net>

On 03Mar2014 09:17, Neal Becker <ndbecker2 at gmail.com> wrote:
>  Charles R Harris <charlesr.harris at gmail.com> Wrote in message:
> > 
> 
> Imo the lesson here is never write in low level c. Use modern
>  languages with well designed exception handling.

What, and rely on someone else's low level C?
-- 
Cameron Simpson <cs at zip.com.au>

Hag:                    Two things you must know about the wise woman.
                        First...she is a woman.  Second...she is...
Edmund Blackadder:      Wise?
Hag:                    Oh! You know her then?
Edmund Blackadder:      No, just a stab in the dark, which is what you'll be
                        getting in a minute if you don't become more helpful.
       - Edmund Blackadder to Old Hag, Bells, BA2


From wolfgang.maier at biologie.uni-freiburg.de  Mon Mar  3 17:15:39 2014
From: wolfgang.maier at biologie.uni-freiburg.de (Wolfgang Maier)
Date: Mon, 3 Mar 2014 14:15:39 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>
 <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>
Message-ID: <27d19767-84ee-4ab7-87fd-784e8ac57680@googlegroups.com>

On Monday, March 3, 2014 9:03:19 PM UTC+1, Mark H. Harris wrote:
> On Monday, March 3, 2014 11:23:13 AM UTC-6, Wolfgang Maier wrote:
> > def fact(x):
> >     """ fact(x)    factorial    {x} int x > 0        
> >
> >     return +Decimal(math.factorial(x)
> > to make it return a Decimal rounded to context precision?
> 
> hi Wolfgang,  I'm not sure.  We're doing some things with very large factorials where (existentially) we want to know how many zeros are coming up and the end of the very large number (thousands of digits) and 2) what are the last significant figures (say twenty of them) that are just before the zero chain.

That's ok, but I do not understand
- why you shouldn't be able to use math.factorial for this purpose and
- why a factorial function accepting and returning ints should be part of your dmath package.

math.factorial is accurate and faster than your pure-Python function, especially for large numbers. Compare:
>>> a = math.factorial(100000)
and your
>>> b = fact(100000)

> What I don't want is for the Decimal module to overflow (didn't know it would do that), and we don't want the number rounded in scientific notation at some number of places. We want to actually see the digits; all of them.

Well, that may be your use-case, but then math.factorial is for you.
On the other hand, you may be interested in getting context-rounded factorials and rounding to context precision is what you'd expect from a Decimal function, so, logically, that's how it should be implemented in your package if you think it needs to have a fact function (which I'm not sure of).

> Python will do multiplications til the proverbial cows come home; well, as long as you don't try it recursively --- killing the recursive depth.

While that's true you pay a heavy price for abusing this feature in terms of performance because with VERY large integers there will be just too much memory shuffling activity. (I haven't looked into how math.factorial handles this internally, but it's certainly performing much better for large numbers than Python integer multiplication.

Best,
Wolfgang


From ben+python at benfinney.id.au  Mon Mar  3 17:18:57 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 04 Mar 2014 09:18:57 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au>
 <mailman.7663.1393882574.18130.python-list@python.org>
 <87wqgb6imm.fsf@elektro.pacujo.net>
Message-ID: <858usrhqni.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Mark Lawrence <breamoreboy at yahoo.co.uk>:
>
> > I'd just like to know why people are so obsessed with identities, I've
> > never thought to use them in 10+ years of writing Python.  Do I use the
> > KISS principle too often?
>
> Calmly choosing the right tool for the job is not an obsession.

Persistently banging your head in contradiction to the facts of Python's
data model, as you have been doing, starts to look very much like
obsession.

-- 
 \                ?Please to bathe inside the tub.? ?hotel room, Japan |
  `\                                                                   |
_o__)                                                                  |
Ben Finney



From marko at pacujo.net  Mon Mar  3 17:22:55 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 04 Mar 2014 00:22:55 +0200
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
Message-ID: <87siqy7whs.fsf@elektro.pacujo.net>

Jerry Hill <malaclypse2 at gmail.com>:

> except for the fact that there has been 20 years of custom saying that
> comparing to None with equality is wrong.

"if foo == None" is not wrong in any manner. It's just that if you are
comfortable with the "is" operator and its semantics, "if foo is None"
is slightly more natural.

You generally use "==" if more than one object could be equal. If you
know there's only one object of the kind, you convey that knowledge by
the use of "is" even when functionally, it doesn't matter.


Marko


From rosuav at gmail.com  Mon Mar  3 17:27:26 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 09:27:26 +1100
Subject: Reference
In-Reply-To: <87siqy7whs.fsf@elektro.pacujo.net>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmqNftMeVKVKVjyPZ+szWuBWe66YP9AuuaquT6qC0sM=kQ@mail.gmail.com>

On Tue, Mar 4, 2014 at 9:22 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> You generally use "==" if more than one object could be equal. If you
> know there's only one object of the kind, you convey that knowledge by
> the use of "is" even when functionally, it doesn't matter.

It's even simpler than that.

You use "==" when you care about value, and "is" when you care about identity.

This is because "==" tests value, and "is" tests identity.

I do not understand why there is confusion.

ChrisA


From ben+python at benfinney.id.au  Mon Mar  3 17:31:48 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 04 Mar 2014 09:31:48 +1100
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <bnkcn8FphikU1@mid.individual.net>
Message-ID: <854n3ej4mj.fsf@benfinney.id.au>

Gregory Ewing <greg.ewing at canterbury.ac.nz> writes:

> Just because the compiler *can* infer the return type doesn't
> necessarily mean it *should*. When I was playing around with
> functional languages, I ended up adopting the practice of always
> declaring the types of my functions, because it helps the *human*
> reader.

Sure. In a duck-typed language like Python, it is still helpful to the
human reader to document the *meaning* of each parameter, beyond what is
indicated by the name. We have reStructuredText and docstrings for this
purpose.

    def frobnicate(flang, splets, queeble=False):
        """ Righteously frobnicate the flang.

            :param flang: A file-like object, opened for reading.
            :param splets: A sequence of unprocessed Splet instances.
            :param queeble: If ``True``, re-vitrify the flang during
                frobnication.
            :return: A new list of processed Splet instances.

            The flang is frobnicated according to the Weebly-Ruckford
            algorithm.

            """
        for line in flang:
            ?

> (It also helped the compiler produce comprehensible error messages in
> the event of a type error.)

Docstrings in the above reStructuredText field-list style will be
processed by Epydoc <URL:http://epydoc.sourceforge.net/fields.html>.

Other styles of specifying parameters in an mechanically-extractable
form are also used, by Sphinx for example. The point is, we have
docstrings, and conventions in docstrings for specifying parameters for
the human reader *and* for automated tools to read.

-- 
 \            ?? Nature ? is seen to do all things Herself and through |
  `\         herself of own accord, rid of all gods.? ?Titus Lucretius |
_o__)                                                 Carus, c. 40 BCE |
Ben Finney



From rosuav at gmail.com  Mon Mar  3 17:25:49 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 09:25:49 +1100
Subject: How security holes happen
In-Reply-To: <20140303221926.GA57537@cskk.homeip.net>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
Message-ID: <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>

On Tue, Mar 4, 2014 at 9:19 AM, Cameron Simpson <cs at zip.com.au> wrote:
> On 03Mar2014 09:17, Neal Becker <ndbecker2 at gmail.com> wrote:
>>  Charles R Harris <charlesr.harris at gmail.com> Wrote in message:
>> >
>>
>> Imo the lesson here is never write in low level c. Use modern
>>  languages with well designed exception handling.
>
> What, and rely on someone else's low level C?

Someone needs to port Python to LISP.

And then write a LISP interpreter in JavaScript.

And an ECMAScript engine in Pike.

And a Pike interpreter in Java.

And a Java run-time written in ActionScript.

It's turtles all the way down...

ChrisA


From ben+python at benfinney.id.au  Mon Mar  3 17:33:36 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 04 Mar 2014 09:33:36 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
Message-ID: <85zjl6hpz3.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Jerry Hill <malaclypse2 at gmail.com>:
>
> > except for the fact that there has been 20 years of custom saying that
> > comparing to None with equality is wrong.
>
> "if foo == None" is not wrong in any manner.

Marko, please don't keep asserting falsehoods. It's already been pointed
out in this forum many times, essentially since the forum existed, why
what you say here is false.

-- 
 \          ?The fact that I have no remedy for all the sorrows of the |
  `\     world is no reason for my accepting yours. It simply supports |
_o__)  the strong probability that yours is a fake.? ?Henry L. Mencken |
Ben Finney



From rosuav at gmail.com  Mon Mar  3 17:42:03 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 09:42:03 +1100
Subject: Functional programming
In-Reply-To: <854n3ej4mj.fsf@benfinney.id.au>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <bnkcn8FphikU1@mid.individual.net> <854n3ej4mj.fsf@benfinney.id.au>
Message-ID: <CAPTjJmqiDw7UwD5haKn2PCGt717XdV9z2kab_5ZwbE6mKmpKpA@mail.gmail.com>

On Tue, Mar 4, 2014 at 9:31 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
>     def frobnicate(flang, splets, queeble=False):
>         """ Righteously frobnicate the flang.
>
>             :param flang: A file-like object, opened for reading.

I had to read that a few times before I was sure that you actually
meant "file" there, you used a real word with its real meaning!

ChrisA


From harrismh777 at gmail.com  Mon Mar  3 17:42:38 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 14:42:38 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <27d19767-84ee-4ab7-87fd-784e8ac57680@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>
 <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>
 <27d19767-84ee-4ab7-87fd-784e8ac57680@googlegroups.com>
Message-ID: <65862588-a0a8-4c3e-a3b2-8848c8170145@googlegroups.com>

On Monday, March 3, 2014 4:15:39 PM UTC-6, Wolfgang Maier wrote:

> Well, that may be your use-case, but then math.factorial is for you.

> On the other hand, you may be interested in getting 
> context-rounded factorials and rounding to context 
> precision is what you'd expect from a Decimal function, 
> so, logically, that's how it should be implemented in your 
> package if you think it needs to have a fact function (which I'm not sure of).


hi Wolfgang,  you are absolutely right. I see what you're getting at
now. I've stuffed something into the library that really does not
belong in that library; it was just convenient for me. I get that.

marcus


From wolfgang.maier at biologie.uni-freiburg.de  Mon Mar  3 17:44:27 2014
From: wolfgang.maier at biologie.uni-freiburg.de (Wolfgang Maier)
Date: Mon, 3 Mar 2014 14:44:27 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <3d7636ab-7544-46db-a1b1-113967dc28d6@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>
 <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>
 <3d7636ab-7544-46db-a1b1-113967dc28d6@googlegroups.com>
Message-ID: <6b871278-47e5-42de-afdf-f42b46a8a459@googlegroups.com>

On Monday, March 3, 2014 10:18:37 PM UTC+1, Mark H. Harris wrote:
> On Monday, March 3, 2014 2:03:19 PM UTC-6, Mark H. Harris wrote:
> 
> Wolfgang,  answer is not so much, in fact, not at all. 
> But it is an interesting question for me; where I am 
> continuing to learn the limits of Decimal, and the 
> decimal context. I don't need rounding for integer 
> multiplication, of course.
>
 
You don't want it and you don't get it for integer multiplication, but you may get it with Decimal multiplication and not high-enough precision:

>>> with localcontext() as ctx:
    	ctx.prec=2
	Decimal(11)*Decimal(11)
	
Decimal('1.2E+2')

This is the very nature of rounding to context precision and functions dealing with Decimals shouldn't behave differently in my opinion. If you don't want rounding either use sufficiently high precision or use integers.

> 
> I am interested in arbitrary limits, like emax, for instance. 
> The doc is a little ambiguous. Is emax the max exponent, 
> and if so, is 999999999 the limit, or is that the default 
> context value which might be bumped up? 
>

I don't find much ambiguity in the docs here:

" class decimal.Context(prec=None, rounding=None, Emin=None, Emax=None, capitals=None, clamp=None, flags=None, traps=None)

    Creates a new context. If a field is not specified or is None, the default values are copied from the DefaultContext. If the flags field is not specified or is None, all flags are cleared.
..
    The Emin and Emax fields are integers specifying the outer limits allowable for exponents. Emin must be in the range [MIN_EMIN, 0], Emax in the range [0, MAX_EMAX]."

So, Emax is the maximal exponent allowed in a specific context and the constant MAX_EMAX is the maximum Emax that you can set in any context.
Also (on my system):

>>> from decimal import getcontext
>>> getcontext()

Context(prec=28, rounding=ROUND_HALF_EVEN, Emin=-999999, Emax=999999, capitals=1, clamp=0, flags=[], traps=[InvalidOperation, DivisionByZero, Overflow])

shows that my default context Emax is way smaller than MAX_EMAX.


> I have discovered just by playing with integer multiplication  
> that those BIGNUMS don't seem to have a physical limit. Of 
> course there isn't a decimal to keep track of, and they can 
> just grow and grow; wouldn't want to make a Decimal from 
> one of those, other than it is interesting to me as I'm trying
> to understand Decimal floating point.
>

decimal can handle BIGNUMS fairly well, you just need to increase context Emax. Have you ever tried to calculate stuff with ints as big as MAX_EMAX (10**999999999999999999) or even close to it and still had a responsive system ??
My point in suggesting the fix for your epx function was that the unnecessary juggling of extremely large values (Decimal or int) is a killer for performance.

> marcus


From breamoreboy at yahoo.co.uk  Mon Mar  3 17:50:24 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 03 Mar 2014 22:50:24 +0000
Subject: How security holes happen
In-Reply-To: <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
Message-ID: <lf30v8$r4o$1@ger.gmane.org>

On 03/03/2014 22:25, Chris Angelico wrote:
> On Tue, Mar 4, 2014 at 9:19 AM, Cameron Simpson <cs at zip.com.au> wrote:
>> On 03Mar2014 09:17, Neal Becker <ndbecker2 at gmail.com> wrote:
>>>   Charles R Harris <charlesr.harris at gmail.com> Wrote in message:
>>>>
>>>
>>> Imo the lesson here is never write in low level c. Use modern
>>>   languages with well designed exception handling.
>>
>> What, and rely on someone else's low level C?
>
> Someone needs to port Python to LISP.
>
> And then write a LISP interpreter in JavaScript.
>
> And an ECMAScript engine in Pike.
>
> And a Pike interpreter in Java.
>
> And a Java run-time written in ActionScript.
>
> It's turtles all the way down...
>
> ChrisA
>

Or write every language in Applescript which has 42 not very obvious 
ways of doing each and everything.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ckaynor at zindagigames.com  Mon Mar  3 17:55:32 2014
From: ckaynor at zindagigames.com (Chris Kaynor)
Date: Mon, 3 Mar 2014 14:55:32 -0800
Subject: How security holes happen
In-Reply-To: <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
Message-ID: <CALvWhxvci3YXDogmQL4aE+OSbf_b0xeyg6ppkaVg6zPgq+jrzw@mail.gmail.com>

On Mon, Mar 3, 2014 at 2:25 PM, Chris Angelico <rosuav at gmail.com> wrote:

> On Tue, Mar 4, 2014 at 9:19 AM, Cameron Simpson <cs at zip.com.au> wrote:
> > On 03Mar2014 09:17, Neal Becker <ndbecker2 at gmail.com> wrote:
> >>  Charles R Harris <charlesr.harris at gmail.com> Wrote in message:
> >> >
> >>
> >> Imo the lesson here is never write in low level c. Use modern
> >>  languages with well designed exception handling.
> >
> > What, and rely on someone else's low level C?
>
> Someone needs to port Python to LISP.
>
> And then write a LISP interpreter in JavaScript.
>
> And an ECMAScript engine in Pike.
>
> And a Pike interpreter in Java.
>
> And a Java run-time written in ActionScript.
>
> It's turtles all the way down...
>

You can go much simpler than that. Merely port Python to LISP, then write a
LISP interpreter in Python. Done.

Now, bootstrapping those interpreters might pose a bit of a challenge...


>
> ChrisA
> --
> https://mail.python.org/mailman/listinfo/python-list
>
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From rosuav at gmail.com  Mon Mar  3 18:03:53 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 10:03:53 +1100
Subject: How security holes happen
In-Reply-To: <CALvWhxvci3YXDogmQL4aE+OSbf_b0xeyg6ppkaVg6zPgq+jrzw@mail.gmail.com>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <CALvWhxvci3YXDogmQL4aE+OSbf_b0xeyg6ppkaVg6zPgq+jrzw@mail.gmail.com>
Message-ID: <CAPTjJmqrRqc6sVfKJ7LUh3PPJDZbgQNQJS63Ee3nFF-zWgKmfQ@mail.gmail.com>

On Tue, Mar 4, 2014 at 9:55 AM, Chris Kaynor <ckaynor at zindagigames.com> wrote:
> You can go much simpler than that. Merely port Python to LISP, then write a
> LISP interpreter in Python. Done.

Actually, here's an easier way. Just write an 80x86 assembly language
interpreter in Python, then port CPython to Python.

ChrisA


From roy at panix.com  Mon Mar  3 18:02:04 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 03 Mar 2014 18:02:04 -0500
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <CADwdpyYP1XzcSRq38g4ugED8HEaZN3KOFmQMwXcojnLqQSiwgw@mail.gmail.com>
 <mailman.7669.1393885090.18130.python-list@python.org>
Message-ID: <roy-F1E46D.18020403032014@news.panix.com>

In article <mailman.7669.1393885090.18130.python-list at python.org>,
 Ben Finney <ben+python at benfinney.id.au> wrote:

> That's right. Python provides this singleton and then recommends you
> compare with ???is???, precisely to protect against pathological cases like
> a ???return True when compared for equality with None??? data type.

Going off on a tangent, I've often wished Python provided more kinds of 
None-ness.  I'll often write:

def f(arg=None):
   whatever

where it would be nice to differentiate between "this was called with no 
arguments" and "this was called with an argument of None".  Sure, I can 
work around that with things like **kwargs, and then test

"args" in kwargs

vs.

kwargs["args"] is None

but that always feels clumsy.  It also makes the function declaration 
less sell-describing.  "Hmmm, let's see what help() says.  Oh, gee, I 
can pass it some stuff".


From rosuav at gmail.com  Mon Mar  3 18:09:28 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 10:09:28 +1100
Subject: Reference
In-Reply-To: <roy-F1E46D.18020403032014@news.panix.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <CADwdpyYP1XzcSRq38g4ugED8HEaZN3KOFmQMwXcojnLqQSiwgw@mail.gmail.com>
 <mailman.7669.1393885090.18130.python-list@python.org>
 <roy-F1E46D.18020403032014@news.panix.com>
Message-ID: <CAPTjJmpdc9B4DNyhoCCmxhraztkLqHiKBbcPFdhFMOt_h=HToQ@mail.gmail.com>

On Tue, Mar 4, 2014 at 10:02 AM, Roy Smith <roy at panix.com> wrote:
> In article <mailman.7669.1393885090.18130.python-list at python.org>,
>  Ben Finney <ben+python at benfinney.id.au> wrote:
>
>> That's right. Python provides this singleton and then recommends you
>> compare with ?is?, precisely to protect against pathological cases like
>> a ?return True when compared for equality with None? data type.
>
> Going off on a tangent, I've often wished Python provided more kinds of
> None-ness.  I'll often write:
>
> def f(arg=None):
>    whatever
>
> where it would be nice to differentiate between "this was called with no
> arguments" and "this was called with an argument of None".

That's why you have your own sentinel.

_NONE_PASSED=object()
def f(arg=_NONE_PASSED):
    if f is not _NONE_PASSED: pass

ChrisA


From roy at panix.com  Mon Mar  3 18:05:08 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 03 Mar 2014 18:05:08 -0500
Subject: How security holes happen
References: <lf22t1$sgh$1@ger.gmane.org>
 <mailman.7670.1393885170.18130.python-list@python.org>
Message-ID: <roy-F4C234.18050803032014@news.panix.com>

In article <mailman.7670.1393885170.18130.python-list at python.org>,
 Cameron Simpson <cs at zip.com.au> wrote:

> On 03Mar2014 09:17, Neal Becker <ndbecker2 at gmail.com> wrote:
> >  Charles R Harris <charlesr.harris at gmail.com> Wrote in message:
> > > 
> > 
> > Imo the lesson here is never write in low level c. Use modern
> >  languages with well designed exception handling.
> 
> What, and rely on someone else's low level C?

Don't laugh.  http://c2.com/cgi/wiki?TheKenThompsonHack


From rosuav at gmail.com  Mon Mar  3 18:36:03 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 10:36:03 +1100
Subject: How security holes happen
In-Reply-To: <roy-F4C234.18050803032014@news.panix.com>
References: <lf22t1$sgh$1@ger.gmane.org>
 <mailman.7670.1393885170.18130.python-list@python.org>
 <roy-F4C234.18050803032014@news.panix.com>
Message-ID: <CAPTjJmrxqqrr-sN8ApA-gN5KXOUZ=VqiixCB27AkOQesq+B0GQ@mail.gmail.com>

On Tue, Mar 4, 2014 at 10:05 AM, Roy Smith <roy at panix.com> wrote:
> In article <mailman.7670.1393885170.18130.python-list at python.org>,
>  Cameron Simpson <cs at zip.com.au> wrote:
>
>> On 03Mar2014 09:17, Neal Becker <ndbecker2 at gmail.com> wrote:
>> >  Charles R Harris <charlesr.harris at gmail.com> Wrote in message:
>> > >
>> >
>> > Imo the lesson here is never write in low level c. Use modern
>> >  languages with well designed exception handling.
>>
>> What, and rely on someone else's low level C?
>
> Don't laugh.  http://c2.com/cgi/wiki?TheKenThompsonHack

I don't think malicious interference with C compilers is the issue
here, so much as the constant discovery of flaws in honestly-written C
code.

Currently, I'm porting a MUD client from C++ to Pike. On average, a
hunk of code shrinks by about 50% during the translation, mainly
because I can let memory management happen elsewhere. (Sometimes the
difference is even more dramatic. I wrote my own binary tree in the
C++ client, because the compiler I was targeting at the time didn't
provide a suitable mapping type; now, I just call on the language's
facilities, and it's more efficient and takes no code whatsoever.
That's basically one entire module eliminated.) Along the way, I'm
noticing myriad little issues around the place, where too much data
would result in something being truncated (I was careful in most
places to ensure that it couldn't blow the stack, although I certainly
wouldn't bet money that I was perfect on that score), and the
truncation could have unexpected results. Malformed data coming in
over a TCP socket would eventually consume all the buffer space and
then make the client think the other end had closed its connection.
That one I knew about and didn't care, but there were others that were
weird and esoteric and would *most likely* never happen.

Writing low level code opens you up to a huge collection of weird
behaviours that might, at best, become bug reports that you spend
hours trying to solve. At worst, they become exploits. Yes, high level
languages have their own attack vectors, but I'd much rather have the
entire python-dev team working to solve my problems than me alone :)

ChrisA


From ben+python at benfinney.id.au  Mon Mar  3 18:52:53 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 04 Mar 2014 10:52:53 +1100
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <bnkcn8FphikU1@mid.individual.net> <854n3ej4mj.fsf@benfinney.id.au>
 <CAPTjJmqiDw7UwD5haKn2PCGt717XdV9z2kab_5ZwbE6mKmpKpA@mail.gmail.com>
Message-ID: <85ppm2hmay.fsf@benfinney.id.au>

Chris Angelico <rosuav at gmail.com> writes:

> On Tue, Mar 4, 2014 at 9:31 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> >     def frobnicate(flang, splets, queeble=False):
> >         """ Righteously frobnicate the flang.
> >
> >             :param flang: A file-like object, opened for reading.
>
> I had to read that a few times before I was sure that you actually
> meant "file" there, you used a real word with its real meaning!

Sometimes I say what I mean, to test whether people are alert.

-- 
 \       ?Faith, n. Belief without evidence in what is told by one who |
  `\   speaks without knowledge, of things without parallel.? ?Ambrose |
_o__)                           Bierce, _The Devil's Dictionary_, 1906 |
Ben Finney



From dihedral88888 at gmail.com  Mon Mar  3 19:35:34 2014
From: dihedral88888 at gmail.com (88888 Dihedral)
Date: Mon, 3 Mar 2014 16:35:34 -0800 (PST)
Subject: Functional programming
In-Reply-To: <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
Message-ID: <862fca31-9154-4fb9-b02e-869c9e575efe@googlegroups.com>

On Monday, March 3, 2014 10:08:11 PM UTC+8, Rustom Mody wrote:
> On Monday, March 3, 2014 7:30:17 PM UTC+5:30, Chris Angelico wrote:
> 
> > On Tue, Mar 4, 2014 at 12:48 AM, Rustom Mody wrote:
> 
> > > ? [1,2] + [[3,4],[5]]
> 
> > > ERROR: Type error in application
> 
> > > *** expression     : [1,2] + [[3,4],[5]]
> 
> > > *** term           : [1,2]
> 
> > > *** type           : [Int]
> 
> > > *** does not match : [[Int]]
> 
> > > IOW [1,2,[3,4],[5]]
> 
> > > is a type-wise ill-formed expression just as in python
> 
> > > [[1,2])
> 
> > > is syntax-wise ill-formed
> 
> > > Is it worth having such a restriction?
> 
> > > Thats a different argument...
> 
> 
> 
> > How do you know that [1,2] is a list that must contain nothing but
> 
> > integers? By extension, it's also a list that must contain positive
> 
> > integers less than three, so adding [5] violates that. And [] is a
> 
> > list that must contain nothing, ergo it can't be added to, although
> 
> > (since it contains nothing) it can be added to anything.
> 
> 
> 
> If 'integer-less-than-3' were a type then yes there would be this
> 
> problem. More generally, if types could overlap then automatic
> 
> type-inference is impossible
> 
> 
> 
> Whether all thats good is as I earlier said a different argument
> 
> 
> 
> The OP asked about FP and so its appropriate to mention how python's
> 
> and standard FPL's choices differ

OK, lets talk about the real 
meats of high-level dynamical typed
languages.

Test the claim that the old OOP programs and modules can use the new objects and programs written or obtained later in the run time.


From harrismh777 at gmail.com  Mon Mar  3 20:22:33 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 17:22:33 -0800 (PST)
Subject: pip and distutils2-1.0a4
In-Reply-To: <mailman.7667.1393884714.18130.python-list@python.org>
References: <248fe774-aed4-4a59-afac-e746e2110dd7@googlegroups.com>
 <mailman.7656.1393880003.18130.python-list@python.org>
 <acf1abdd-b0e7-4d4f-ab76-18c2998b8742@googlegroups.com>
 <mailman.7662.1393882380.18130.python-list@python.org>
 <31feb451-7fb6-48a6-9986-bddce69c4991@googlegroups.com>
 <mailman.7667.1393884714.18130.python-list@python.org>
Message-ID: <1279b5f0-aff5-429d-a8d0-a9d93cc48242@googlegroups.com>

On Monday, March 3, 2014 4:11:44 PM UTC-6, Robert Kern wrote:

>    http://docs.python.org/3/distutils/index.html

> Robert Kern

hi Robert,  I'm not whining --really-- but there is so dang much
doc out there on how to upload a package to PyPI with every tool
under the sun and all of them fancier than they need to be. So,
that you!  That doc file led me to another doc file that showed me
how to build the setup.py file line by line. 
The real trick is building the src tree (and there are more than several
ways to do that) and then matching the setup.py script to the src
tree:  then,
python3 setup.py register
python3 setup.py sdist upload
python3 setup.py upload

whew...  I never worked so hard to get one silly tarball on a repository
in my life ever...  very rewarding;  but, and I genuinely mean this, thank
you for pointing me in the correct direction, sir.

marcus


From abhishek1899 at gmail.com  Mon Mar  3 20:33:15 2014
From: abhishek1899 at gmail.com (Rolando)
Date: Mon, 3 Mar 2014 17:33:15 -0800 (PST)
Subject: Idle thread (Polling) python GUI and saving program state
Message-ID: <da3d9fc2-91a9-4fd4-a7b9-7c3825e2ca65@googlegroups.com>

I have a GUI with a bunch of cells which is my "View" in the MVC design. The user enters some information in the view and I pass this on to the model so that using the information entered by the user it(model) can do some processing.

I have coded up my model as a state machine. Wherein, once a function is complete it switches to the next state and so on.

I want to know how do I save the program state between restarts. Basically, I'm trying to handle a scenario wherein if someone closes the program. The next time someone starts it up, it should start from where it left off (both the view and model)

Also, I want to setup a poll method where once in a while I can poll each cell to know the state it is in. How do I do this? I don't want my GUI to hang when I'm doing anything. It will be great if someone could help. Thanks!


From harrismh777 at gmail.com  Mon Mar  3 20:42:16 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 17:42:16 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <6b871278-47e5-42de-afdf-f42b46a8a459@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>
 <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>
 <3d7636ab-7544-46db-a1b1-113967dc28d6@googlegroups.com>
 <6b871278-47e5-42de-afdf-f42b46a8a459@googlegroups.com>
Message-ID: <3b2f4dbc-fa84-4a41-9632-946e99def48e@googlegroups.com>

On Monday, March 3, 2014 4:44:27 PM UTC-6, Wolfgang Maier wrote:

> decimal can handle BIGNUMS fairly well, you just need to increase context Emax. Have you ever tried to calculate stuff with ints as big as MAX_EMAX (10**999999999999999999) or even close to it and still had a responsive system ??

hi Wolfgang,  yes correct you are...  I've been playing with it; very 
interesting. I think I've almost got my arms around these things.
If I don't get it right in my head, then my library is gonna suck. Still
looking, but I think I may have one or two more funcs that have a
similar problem to epx(). I've decided to go through them one by 
one while I'm testing and make sure that they are as efficient as I can
make them.  Thanks again for your inputs.

marcus


From harrismh777 at gmail.com  Mon Mar  3 20:46:38 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 3 Mar 2014 17:46:38 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
Message-ID: <4c40a0a4-e8ee-422a-a227-4a1a0597bb81@googlegroups.com>

On Monday, March 3, 2014 5:34:30 AM UTC-6, Mark H. Harris wrote:

> https://code.google.com/p/pythondecimallibrary/

I released my  pdeclib module  this afternoon on PyPI here:

   https://pypi.python.org/pypi/pdeclib/0.3

The tarball.gz may be downloaded and installed with:

   pip install pdeclib

Contains:    pdeclib.py | pilib.py

Thanks again to all who helped me with this beta package.


Cheers,
marcus


From python at mrabarnett.plus.com  Mon Mar  3 21:06:22 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 04 Mar 2014 02:06:22 +0000
Subject: Idle thread (Polling) python GUI and saving program state
In-Reply-To: <da3d9fc2-91a9-4fd4-a7b9-7c3825e2ca65@googlegroups.com>
References: <da3d9fc2-91a9-4fd4-a7b9-7c3825e2ca65@googlegroups.com>
Message-ID: <5315351E.9040308@mrabarnett.plus.com>

On 2014-03-04 01:33, Rolando wrote:
 > I have a GUI with a bunch of cells which is my "View" in the MVC
 > design. The user enters some information in the view and I pass this
 > on to the model so that using the information entered by the user
 > it(model) can do some processing.
 >
 > I have coded up my model as a state machine. Wherein, once a function
 > is complete it switches to the next state and so on.
 >
 > I want to know how do I save the program state between restarts.
 > Basically, I'm trying to handle a scenario wherein if someone closes
 > the program. The next time someone starts it up, it should start from
 > where it left off (both the view and model)
 >
When the user closes the window (you don't say what you're using for
the GUI, but there should be a way of detecting when window closes),
save the necessary info to a file using, say, the 'json' module. You
can then reload the info from the file when the program is restarted.

 > Also, I want to setup a poll method where once in a while I can poll
 > each cell to know the state it is in. How do I do this? I don't want
 > my GUI to hang when I'm doing anything. It will be great if someone
 > could help. Thanks!
 >
Can the model run continuously? If so, you should run it in its own
(background) thread and the GUI in the main thread and communicate
with the model's thread via, say, a queue (for that use the 'queue'
module).


From rosuav at gmail.com  Mon Mar  3 21:13:24 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 13:13:24 +1100
Subject: Origin of 'self'
In-Reply-To: <7edah9989mdjb9mrnrsh5067np0ihv1jml@4ax.com>
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
 <7edah9989mdjb9mrnrsh5067np0ihv1jml@4ax.com>
Message-ID: <CAPTjJmos2cmO7L=uXS1s1oEDybmqfWB2G_DVJ=bz=7qFSz45cg@mail.gmail.com>

On Tue, Mar 4, 2014 at 1:09 PM, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> On Sun, 2 Mar 2014 22:16:31 -0800 (PST), Westley Mart?nez
> <anikom15 at gmail.com> declaimed the following:
>
>>I understand that in an object method the first argument in the object itself, called self.  However, it doesn't have to be called self, and can be called anything.  So my question is why is it called self and not this like from C++ and Java.  It's kind of a silly question, but one that I'm curious about nevertheless.
>>
>
>         It didn't want to be egotistical (as I recall, M$ VB uses "me")

ALL language designers are egotistical. Goes with the territory.

(Larry Wall said that, I believe, regarding Perl.)

ChrisA


From roy at panix.com  Mon Mar  3 21:14:44 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 03 Mar 2014 21:14:44 -0500
Subject: Origin of 'self'
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
 <mailman.7684.1393898999.18130.python-list@python.org>
Message-ID: <roy-E7C2E0.21144403032014@news.panix.com>

In article <mailman.7684.1393898999.18130.python-list at python.org>,
 Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:

> On Sun, 2 Mar 2014 22:16:31 -0800 (PST), Westley Mart?nez
> <anikom15 at gmail.com> declaimed the following:
> 
> >I understand that in an object method the first argument in the object 
> >itself, called self.  However, it doesn't have to be called self, and can be 
> >called anything.  So my question is why is it called self and not this like 
> >from C++ and Java.  It's kind of a silly question, but one that I'm curious 
> >about nevertheless.
> >
> 
> 	It didn't want to be egotistical (as I recall, M$ VB uses "me")

And Freud uses "id", but that was taken already in Python :-)


From zachary.ware+pylist at gmail.com  Mon Mar  3 21:24:27 2014
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Mon, 3 Mar 2014 20:24:27 -0600
Subject: 3.4rc2 and pip on windows
In-Reply-To: <CAKJDb-Mo=j=1znZURUNvDN6q20WjmVv-S4O=xMC9mH6BTjy6tQ@mail.gmail.com>
References: <lf0ge3$fbv$1@ger.gmane.org> <lf0h42$l88$2@ger.gmane.org>
 <lf2m8g$ouv$1@ger.gmane.org>
 <CAKJDb-Mo=j=1znZURUNvDN6q20WjmVv-S4O=xMC9mH6BTjy6tQ@mail.gmail.com>
Message-ID: <CAKJDb-OwrgCiTXZmBuzw534sHhsY5CjMLAfcnO+6rDKrzbEJyw@mail.gmail.com>

On Mon, Mar 3, 2014 at 3:48 PM, Zachary Ware
<zachary.ware+pylist at gmail.com> wrote:
> It could be argued that Pip could compile any .py files that it
> installs and just start screaming if it gets any SyntaxError, but what
> if your package (for some weird reason) relies on .py file with bad
> syntax?

Somehow, I missed that this is exactly what seems to be happening,
sans screaming.  So yes, Pip is doing this slightly wrong, but it's
still on the package author to fix it properly.  But it's still not a
Python issue, since Pip is still a separate project.

-- 
Zach

On Mon, Mar 3, 2014 at 3:48 PM, Zachary Ware
<zachary.ware+pylist at gmail.com> wrote:
> On Mon, Mar 3, 2014 at 1:47 PM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>> FTR I raised this as http://bugs.python.org/issue20846 and it was closed 11
>> minutes after I raised it.  I won't say anything else as I'm extremely tired
>> and irritable and might well regret it later.
>
> Best I can tell, the issue was closed correctly.  It doesn't look like
> a Python or Pip bug, it looks like a bug in pyttsx's packaging.  Based
> on empirical data [1], Pip does properly take care of running 2to3,
> but *only when told to do so*.  Pip can't decide whether it should run
> 2to3 when it hasn't been told either way, because it's not safe.  It
> can't try compiling .py files and running 2to3 if it gets
> SyntaxErrors, because what if the SyntaxError is just a SyntaxError,
> and not a ThisHasntBeenPortedToPython3Error?  Then 2to3 might blow up,
> possibly leaving things in a state that makes the underlying issue
> very hard to find.  It can't try importing the installed package,
> because what if importing without specific external state in place has
> ugly side-effects?  Pip can't safely do anything it's not told to do
> with the packages it installs because then responsibility for the fire
> in your hard drive could be laid at Pip's feet, not the evil evil
> package author who wrote the code that started the fire.
>
> It could be argued that Pip could compile any .py files that it
> installs and just start screaming if it gets any SyntaxError, but what
> if your package (for some weird reason) relies on .py file with bad
> syntax?
>
> I don't think Python itself is involved at all here, and I think Pip
> is doing the right thing.  Everything installed successfully into the
> right place (since `import pyttsx` did find the package); the fact
> that it SyntaxError'd out is on the package author.
>
> My 0.02USD, anyway.
>
> --
> Zach
>
> [1] `pip install sphinx` from a 3.4 venv



-- 
Zach


From abhishek1899 at gmail.com  Mon Mar  3 21:41:54 2014
From: abhishek1899 at gmail.com (Rolando)
Date: Mon, 3 Mar 2014 18:41:54 -0800 (PST)
Subject: Idle thread (Polling) python GUI and saving program state
In-Reply-To: <mailman.7683.1393898784.18130.python-list@python.org>
References: <da3d9fc2-91a9-4fd4-a7b9-7c3825e2ca65@googlegroups.com>
 <mailman.7683.1393898784.18130.python-list@python.org>
Message-ID: <4034b33f-0cb6-46fa-931c-450834c98d6e@googlegroups.com>

On Monday, March 3, 2014 6:06:22 PM UTC-8, MRAB wrote:
> On 2014-03-04 01:33, Rolando wrote:
> 
>  > I have a GUI with a bunch of cells which is my "View" in the MVC
> 
>  > design. The user enters some information in the view and I pass this
> 
>  > on to the model so that using the information entered by the user
> 
>  > it(model) can do some processing.
> 
>  >
> 
>  > I have coded up my model as a state machine. Wherein, once a function
> 
>  > is complete it switches to the next state and so on.
> 
>  >
> 
>  > I want to know how do I save the program state between restarts.
> 
>  > Basically, I'm trying to handle a scenario wherein if someone closes
> 
>  > the program. The next time someone starts it up, it should start from
> 
>  > where it left off (both the view and model)
> 
>  >
> 
> When the user closes the window (you don't say what you're using for
> 
> the GUI, but there should be a way of detecting when window closes),
> 
> save the necessary info to a file using, say, the 'json' module. You
> 
> can then reload the info from the file when the program is restarted.
> 
> 
> 
>  > Also, I want to setup a poll method where once in a while I can poll
> 
>  > each cell to know the state it is in. How do I do this? I don't want
> 
>  > my GUI to hang when I'm doing anything. It will be great if someone
> 
>  > could help. Thanks!
> 
>  >
> 
> Can the model run continuously? If so, you should run it in its own
> 
> (background) thread and the GUI in the main thread and communicate
> 
> with the model's thread via, say, a queue (for that use the 'queue'
> 
> module).

I'm using wxPython for my GUI. I have tried running the model thread in the background. But how will I save the state if the whole model is running on a thread? When the program is restarted I want the program to continue from the same state where it left off for each cell. I was thinking of having an idle thread that calls a poll method which polls all the cells and checks what each one is doing. But, I don't know how to do that. I'm confused.


From albert at spenarnc.xs4all.nl  Mon Mar  3 21:45:58 2014
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 04 Mar 2014 02:45:58 GMT
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
Message-ID: <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>

In article <mailman.6735.1392194885.18130.python-list at python.org>,
Chris Angelico  <rosuav at gmail.com> wrote:
>On Wed, Feb 12, 2014 at 7:17 PM, Ben Finney <ben+python at benfinney.id.au> wrote:
>> Chris Angelico <rosuav at gmail.com> writes:
>>
>>> I have yet to find any computer that works with the set of real
>>> numbers in any way. Never mind optimization, they simply cannot work
>>> with real numbers.
>>
>> Not *any* computer? Not in *any* way? The Python built-in ???float??? type
>> ???works with the set of real numbers???, in a way.
>
>No, the Python built-in float type works with a subset of real numbers:

To be more precise: a subset of the rational numbers, those with a denominator
that is a power of two.
>
>>>> float("pi")
>Traceback (most recent call last):
>  File "<pyshell#1>", line 1, in <module>
>    float("pi")
>ValueError: could not convert string to float: 'pi'
>>>> float("??")
>Traceback (most recent call last):
>  File "<pyshell#2>", line 1, in <module>
>    float("??")
>ValueError: could not convert string to float: '??'
>
>Same goes for fractions.Fraction and [c]decimal.Decimal. All of them
>are restricted to some subset of rational numbers, not all reals.
>
>> The <URL:http://docs.python.org/2/library/numbers.html#numbers.Real> ABC
>> defines behaviours for types implementing the set of real numbers.
>>
>> What specific behaviour would, for you, qualify as ???works with the set
>> of real numbers in any way????
>
>Being able to represent surds, pi, e, etc, for a start. It'd
>theoretically be possible with an algebraic notation (eg by carrying
>through some representation like "2*pi" rather than 6.28....), but
>otherwise, irrationals can't be represented with finite storage and a
>digit-based system.

An interesting possibility is working with rules that generate the
continued fraction sequence of a real number. Say yield() gives the
next coefficient (or the next hex digit).
It was generally believed that summing two numbers in their cf representation
was totally impractical because it required conversion to a rational number.
OTOH if we consider a cf as an ongoing progress, the situation is much better.
Summing would be a process that yields coefficients of the sum, and you could
just stop when you've  enough precision. Fascinating stuff.

It is described in a self contained, type writer style document gosper.txt
that is found on the web in several places e.g.

http://home.strw.leidenuniv.nl/~gurkan/gosper.pdf
I have a gosper.txt, don't know from where.

It really is a cookbook, one could built a python implementation from
there, without being overly math savvy. I'd love to hear if
some one does it.

( in principle a coefficient of a cf can overflow machine precision,
that has never been observed in the wild. A considerable percentage
of the coefficients for a random number are ones or otherwise small.
The golden ratio has all ones.)
>
>ChrisA

Groetjes Albert
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From rosuav at gmail.com  Mon Mar  3 22:02:01 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 14:02:01 +1100
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
Message-ID: <CAPTjJmqniLwQa+vdidDQbjcSy7t7N12LB8oWPtX5xNNPeq-N_Q@mail.gmail.com>

On Tue, Mar 4, 2014 at 1:45 PM, Albert van der Horst
<albert at spenarnc.xs4all.nl> wrote:
>>No, the Python built-in float type works with a subset of real numbers:
>
> To be more precise: a subset of the rational numbers, those with a denominator
> that is a power of two.

And no more than N bits (53 in a 64-bit float) in the numerator, and
the denominator between the limits of the exponent. (Unless it's
subnormal. That adds another set of small numbers.) It's a pretty
tight set of restrictions, and yet good enough for so many purposes.

But it's a far cry from "all real numbers". Even allowing for
continued fractions adds only some more; I don't think you can
represent surds that way.

ChrisA


From rustompmody at gmail.com  Mon Mar  3 22:13:58 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 19:13:58 -0800 (PST)
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <mailman.7687.1393902132.18130.python-list@python.org>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
Message-ID: <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>

On Tuesday, March 4, 2014 8:32:01 AM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 4, 2014 at 1:45 PM, Albert van der Horst wrote:
> >>No, the Python built-in float type works with a subset of real numbers:
> > To be more precise: a subset of the rational numbers, those with a denominator
> > that is a power of two.

> And no more than N bits (53 in a 64-bit float) in the numerator, and
> the denominator between the limits of the exponent. (Unless it's
> subnormal. That adds another set of small numbers.) It's a pretty
> tight set of restrictions, and yet good enough for so many purposes.

> But it's a far cry from "all real numbers". Even allowing for
> continued fractions adds only some more; I don't think you can
> represent surds that way.

See

http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/cfINTRO.html#sqrts



From nad at acm.org  Mon Mar  3 22:38:24 2014
From: nad at acm.org (Ned Deily)
Date: Mon, 03 Mar 2014 19:38:24 -0800
Subject: 3.4rc2 and pip on windows
References: <lf0ge3$fbv$1@ger.gmane.org> <lf0h42$l88$2@ger.gmane.org>
 <lf2m8g$ouv$1@ger.gmane.org>
 <CAKJDb-Mo=j=1znZURUNvDN6q20WjmVv-S4O=xMC9mH6BTjy6tQ@mail.gmail.com>
 <CAKJDb-OwrgCiTXZmBuzw534sHhsY5CjMLAfcnO+6rDKrzbEJyw@mail.gmail.com>
Message-ID: <nad-B1BA8D.19382303032014@news.gmane.org>

In article 
<CAKJDb-OwrgCiTXZmBuzw534sHhsY5CjMLAfcnO+6rDKrzbEJyw at mail.gmail.com>,
 Zachary Ware <zachary.ware+pylist at gmail.com> wrote:
> On Mon, Mar 3, 2014 at 3:48 PM, Zachary Ware
> <zachary.ware+pylist at gmail.com> wrote:
> > It could be argued that Pip could compile any .py files that it
> > installs and just start screaming if it gets any SyntaxError, but what
> > if your package (for some weird reason) relies on .py file with bad
> > syntax? 
> Somehow, I missed that this is exactly what seems to be happening,
> sans screaming.  So yes, Pip is doing this slightly wrong, but it's
> still on the package author to fix it properly.  But it's still not a
> Python issue, since Pip is still a separate project.

FTR, pip is not doing anything wrong: see the updates to Issue20846 and 
the discussion on python-dev.  The "syntax error" messages displayed are 
warnings which originate from Distutils (which is called by pip and 
other installers) when it tries to byte-compiles the installed files, 
which actually do install successfully.  Byte-compiling is merely an 
optimization and installs do not (and should not) depend on them.  But 
just because a package installs without error doesn't mean it executes 
without error.  The real problem is that the package that was trying to 
be installed with Python 3 is not compatible with Python 3 but there is 
currently no way for pip or any other installer to know that, other than 
perhaps by running a package's test suite if one is provided.  The 
package author could include metadata hints ("Requires-Python") about 
which versions of Python are supported by the package but those optional 
hints aren't used today by any installer.  Having more usable and 
reliable metadata is a focus of packaging PEPs in various stages of 
design and development.  The goal is that eventually installers would be 
able to detect Python version mismatches.  Today it is up to the person 
installing a package to determine that.

-- 
 Ned Deily,
 nad at acm.org



From rosuav at gmail.com  Mon Mar  3 22:46:25 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 14:46:25 +1100
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
Message-ID: <CAPTjJmp_GW2cGDrCB_2hpSnuSzOUgzRaS8YmrkQ6bjGKeU_bRg@mail.gmail.com>

On Tue, Mar 4, 2014 at 2:13 PM, Rustom Mody <rustompmody at gmail.com> wrote:
>> But it's a far cry from "all real numbers". Even allowing for
>> continued fractions adds only some more; I don't think you can
>> represent surds that way.
>
> See
>
> http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/cfINTRO.html#sqrts

That's neat, didn't know that. Is there an efficient way to figure
out, for any integer N, what its sqrt's CF sequence is? And what about
the square roots of non-integers - can you represent ?? that way? I
suspect, though I can't prove, that there will be numbers that can't
be represented even with an infinite series - or at least numbers
whose series can't be easily calculated.

ChrisA


From steve at pearwood.info  Mon Mar  3 22:45:55 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 03:45:55 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <mailman.7654.1393872546.18130.python-list@python.org>
Message-ID: <53154c73$0$2923$c3e8da3$76491128@news.astraweb.com>

On Mon, 03 Mar 2014 13:48:39 -0500, Terry Reedy wrote:

> On 3/3/2014 4:42 AM, ast wrote:
> 
>> Consider following code:
>>
>>>>> A=7
>>>>> B=7
>>>>> A is B
> 
> The 'is' operator has three uses, two intended and one not. In
> production code, 'is' tests that an object *is* a particular singular
> object, such as None or a sentinel instance of class object. In test
> code, 'is' can also be used to test details of a particular
> implementation, such as pre-allocation of small ints. New python
> programmers also use it to confuse themselves.


+1 QOTW 



-- 
Steven


From steve at pearwood.info  Mon Mar  3 22:59:03 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 03:59:03 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
Message-ID: <53154f85$0$2923$c3e8da3$76491128@news.astraweb.com>

On Mon, 03 Mar 2014 17:02:14 -0500, Jerry Hill wrote:

> On Mon, Mar 3, 2014 at 4:51 PM, Tim Chase
> <python.list at tim.thechases.com> wrote:
>> There are a couple use-cases I've encountered where "is" matters:
>>
>> 1) the most popular:
>>
>>   if foo is None:
>>     do_stuff()
> 
> I know this is the one that always comes up, but honestly, I feel like
> "is" doesn't matter here.  That code would be just as correct if it was
> written as:
> 
> if foo == None:
>     do_stuff()
> 
> The only time it would give you a different result from the "is" version
> is if foo was bound to an object that returned True when compared with
> None.  And if that were the case, I'm still not convinced that you can
> tell from looking at those two lines of code which one is buggy, 


It's all about the intention of the code.

Are you trying to test whether an object *is* the None singleton, and no 
other value? Then use "is", don't use == because it is subject to false 
positives (returning True for some objects that aren't actually None).

Or do you want to test whether an object merely happens to have the same 
value as None? Then use == and be glad.

Personally, I have never written code that looks like this:

def spam(a, b=None):
    """Spamify a with optional b.

    If b is None ***OR SOMETHING THAT COMPARES EQUAL TO NONE*** 
    or not supplied, use extra-yummy spammification mode.
    """
    if b == None: ...


But if I ever did want to do that, I can.

Since None is a singleton null-object, something with no state and no 
behaviour, we normally treat it as a sentinel, in which case an identity 
test is usual. I can't really think of any good reason to treat it as a 
value where I would want to use an equality test.


> except
> for the fact that there has been 20 years of custom saying that
> comparing to None with equality is wrong.

It's not *necessarily* wrong, merely wrong the 99.9998% of the time that 
you want to treat None as a sentinel.


-- 
Steven


From ikorot01 at gmail.com  Mon Mar  3 23:03:46 2014
From: ikorot01 at gmail.com (Igor Korot)
Date: Mon, 3 Mar 2014 20:03:46 -0800
Subject: How do I process this?
Message-ID: <CA+FnnTzb1CxO7NBRokPi0-NE5VrVUGQ6ATYNhviCjbwEDJ4zpg@mail.gmail.com>

Hi, ALL,
I have a csv file which depending on how it was produced gives 2 different
strings as shown in the example below (test1 and test2).
I am only interested in the first field in test1 and obviously in the whole
string of test2.

So, I tried to see if I can get what I want in one simple way, but failed.
Is it possible to process the file independently?

Thank you.

python
Python 2.7.5 (default, May 15 2013, 22:43:36) [MSC v.1500 32 bit (Intel)]
on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> test1 = "a,,,,"
>>> test2 = "a"
>>> (t1,_) = test1.split(',')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: too many values to unpack
>>> (t2,_) = test2.split(',')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: need more than 1 value to unpack
>>>
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From python.list at tim.thechases.com  Mon Mar  3 23:09:43 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Mon, 3 Mar 2014 22:09:43 -0600
Subject: How do I process this?
In-Reply-To: <CA+FnnTzb1CxO7NBRokPi0-NE5VrVUGQ6ATYNhviCjbwEDJ4zpg@mail.gmail.com>
References: <CA+FnnTzb1CxO7NBRokPi0-NE5VrVUGQ6ATYNhviCjbwEDJ4zpg@mail.gmail.com>
Message-ID: <20140303220943.0a244e96@bigbox.christie.dr>

On 2014-03-03 20:03, Igor Korot wrote:
> Hi, ALL,
> I have a csv file which depending on how it was produced gives 2
> different strings as shown in the example below (test1 and test2).
> I am only interested in the first field in test1 and obviously in
> the whole string of test2.
> 
> So, I tried to see if I can get what I want in one simple way, but
> failed. Is it possible to process the file independently?
> 
> Thank you.
> 
> >>> test1 = "a,,,,"
> >>> test2 = "a"
> >>> (t1,_) = test1.split(',')
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> ValueError: too many values to unpack
> >>> (t2,_) = test2.split(',')
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> ValueError: need more than 1 value to unpack
> >>>

Have you tried

  t = test.split(',', 1)[0]

or

  t = test.partition(',')[0]

Both of which yield the same results for me.

-tkc




From zachary.ware+pylist at gmail.com  Mon Mar  3 23:16:02 2014
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Mon, 3 Mar 2014 22:16:02 -0600
Subject: How do I process this?
In-Reply-To: <CA+FnnTzb1CxO7NBRokPi0-NE5VrVUGQ6ATYNhviCjbwEDJ4zpg@mail.gmail.com>
References: <CA+FnnTzb1CxO7NBRokPi0-NE5VrVUGQ6ATYNhviCjbwEDJ4zpg@mail.gmail.com>
Message-ID: <CAKJDb-NOgNUbuCajU9MDAaWf8Dnyiuw91o5HijmpDCDk3yRM+w@mail.gmail.com>

On Mon, Mar 3, 2014 at 10:03 PM, Igor Korot <ikorot01 at gmail.com> wrote:
> Hi, ALL,
> I have a csv file which depending on how it was produced gives 2 different
> strings as shown in the example below (test1 and test2).
> I am only interested in the first field in test1 and obviously in the whole
> string of test2.
>
> So, I tried to see if I can get what I want in one simple way, but failed.
> Is it possible to process the file independently?
>
> Thank you.
>
> python
> Python 2.7.5 (default, May 15 2013, 22:43:36) [MSC v.1500 32 bit (Intel)] on
> win32
> Type "help", "copyright", "credits" or "license" for more information.
>>>> test1 = "a,,,,"
>>>> test2 = "a"
>>>> (t1,_) = test1.split(',')
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> ValueError: too many values to unpack
>>>> (t2,_) = test2.split(',')
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> ValueError: need more than 1 value to unpack
>>>>

I'm not sure what you mean by "is it possible to process the file
independently", can you expand on that a bit?

As far as what you're trying to do, there are a couple ways to do it.
If you can use Python 3 instead:

T:\emp>py -3
Python 3.3.2 (v3.3.2:d047928ae3f6, May 16 2013, 00:06:53) [MSC v.1600
64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> test1 = "a,,,,"
>>> test2 = "a"
>>> t1, *remainder1 = test1.split(',')
>>> t1
'a'
>>> remainder1
['', '', '', '']
>>> t2, *remainder2 = test2.split(',')
>>> t2
'a'
>>> remainder2
[]
>>> ^Z

Or, if you're stuck on Python 2:

T:\emp>py -2
Python 2.7.5 (default, May 15 2013, 22:44:16) [MSC v.1500 64 bit
(AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> test1 = "a,,,,"
>>> test2 = "a"
>>> t1 = test1.split(',')[0]
>>> t1
'a'
>>> t2 = test2.split(',')[0]
>>> t2
'a'
>>>

Hope this helps,

-- 
Zach


From steve at pearwood.info  Mon Mar  3 23:38:05 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 04:38:05 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <CADwdpyYP1XzcSRq38g4ugED8HEaZN3KOFmQMwXcojnLqQSiwgw@mail.gmail.com>
 <mailman.7669.1393885090.18130.python-list@python.org>
 <roy-F1E46D.18020403032014@news.panix.com>
Message-ID: <531558ac$0$2923$c3e8da3$76491128@news.astraweb.com>

On Mon, 03 Mar 2014 18:02:04 -0500, Roy Smith wrote:

> In article <mailman.7669.1393885090.18130.python-list at python.org>,
>  Ben Finney <ben+python at benfinney.id.au> wrote:
> 
>> That's right. Python provides this singleton and then recommends you
>> compare with ?is?, precisely to protect against pathological cases like
>> a ?return True when compared for equality with None? data type.
> 
> Going off on a tangent, I've often wished Python provided more kinds of
> None-ness.  I'll often write:
> 
> def f(arg=None):
>    whatever
> 
> where it would be nice to differentiate between "this was called with no
> arguments" and "this was called with an argument of None".  Sure, I can
> work around that with things like **kwargs,


That's the hard way. The easy way is:

_SENTINEL = object()

def f(arg=_SENTINEL):
    if arg is _SENTINEL:
        ...


If you really cared, you could implement your own None_ish_Type and 
create as many named sentinels as you wish.


-- 
Steven


From gordon at panix.com  Mon Mar  3 23:46:24 2014
From: gordon at panix.com (John Gordon)
Date: Tue, 4 Mar 2014 04:46:24 +0000 (UTC)
Subject: How do I process this?
References: <mailman.7690.1393905834.18130.python-list@python.org>
Message-ID: <lf3lqv$31v$1@reader1.panix.com>

In <mailman.7690.1393905834.18130.python-list at python.org> Igor Korot <ikorot01 at gmail.com> writes:

> --047d7b6dc250a1426004f3bffd8d
> Content-Type: text/plain; charset=ISO-8859-1

> Hi, ALL,
> I have a csv file which depending on how it was produced gives 2 different
> strings as shown in the example below (test1 and test2).
> I am only interested in the first field in test1 and obviously in the whole
> string of test2.

> So, I tried to see if I can get what I want in one simple way, but failed.
> Is it possible to process the file independently?

> Thank you.

split() returns a list.  Use indexing to grab only the element you want,
like this:

    t1 = test1.split(',')[0]
    t2 = test2.split(',')[0]

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon at panix.com    watch 'House', or a real serial killer to watch 'Dexter'.



From steve at pearwood.info  Mon Mar  3 23:52:38 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 04:52:38 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
Message-ID: <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>

On Tue, 04 Mar 2014 00:22:55 +0200, Marko Rauhamaa wrote:

> Jerry Hill <malaclypse2 at gmail.com>:
> 
>> except for the fact that there has been 20 years of custom saying that
>> comparing to None with equality is wrong.
> 
> "if foo == None" is not wrong in any manner. It's just that if you are
> comfortable with the "is" operator and its semantics, "if foo is None"
> is slightly more natural.
> 
> You generally use "==" if more than one object could be equal. If you
> know there's only one object of the kind, you convey that knowledge by
> the use of "is" even when functionally, it doesn't matter.

I don't agree that it doesn't matter. Code, even when functionally 
equivalent, should express the intention of the programmer in as simple a 
fashion as is possible given the constraints of the task, performance, 
etc. For example, if you want to add 1 to a number, you would write:

x += 1


not:

x += (127 - 102)//(5**2)

even though you know that the two expressions are exactly equivalent. 
Even if you know that there is a peep-hole optimizer that ensures that 
the code actually compiled is "x += 1". The intention to the reader is 
important.

This is why, unless performance is *really* critical, one should normally 
write x*2 when multiplying x by 2 rather than x >> 1. (And in Python, the 
overhead means that there is no real performance benefit to using bit 
shifts instead of multiplication or division.)

If your intention is to treat None as a singleton sentinel, not as a 
value, then you ought to use "is" to signal that intention, rather than 
using == even if you know that there won't be any false positives.



-- 
Steven


From rustompmody at gmail.com  Tue Mar  4 00:19:48 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 21:19:48 -0800 (PST)
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <mailman.7689.1393904790.18130.python-list@python.org>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
Message-ID: <3e6e8aa4-b2f5-4aec-bae3-20423978a4a0@googlegroups.com>

On Tuesday, March 4, 2014 9:16:25 AM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 4, 2014 at 2:13 PM, Rustom Mody  wrote:
> >> But it's a far cry from "all real numbers". Even allowing for
> >> continued fractions adds only some more; I don't think you can
> >> represent surds that way.
> > See
> > http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/cfINTRO.html#sqrts

> That's neat, didn't know that. Is there an efficient way to figure
> out, for any integer N, what its sqrt's CF sequence is? And what about
> the square roots of non-integers - can you represent ?? that way? I
> suspect, though I can't prove, that there will be numbers that can't
> be represented even with an infinite series - or at least numbers
> whose series can't be easily calculated.

You are now asking questions that are really (real-ly?) outside my capacities.

What I know (which may be quite off the mark :-) )

Just as all real numbers almost by definition have a decimal form (may
be infinite eg 1/3 becomes 0.33333...) all real numbers likewise have a CF form

For some mathematical (aka arcane) reasons the CF form is actually better.

Furthermore:

1. Transcendental numbers like e and pi have non-repeating infinite CF forms
2. Algebraic numbers (aka surds) have repeating maybe finite(?) forms
3. For some numbers its not known whether they are transcendental or not
(vague recollection pi^sqrt(pi) is one such)
4 Since e^ipi is very much an integer, above question is surprisingly non-trivial


From rosuav at gmail.com  Tue Mar  4 00:24:03 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 16:24:03 +1100
Subject: Reference
In-Reply-To: <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CAPTjJmrMMkYdiENeyQiELwg=F1hux-73ZZ40786vjQLqBZqWig@mail.gmail.com>

On Tue, Mar 4, 2014 at 3:52 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> This is why, unless performance is *really* critical, one should normally
> write x*2 when multiplying x by 2 rather than x >> 1. (And in Python, the
> overhead means that there is no real performance benefit to using bit
> shifts instead of multiplication or division.)

In most C compilers today (C being where x << 1 would be used rather
than x * 2), the expressions would be equivalent, so you can still
express it as x * 2 and let the compiler turn that into a bit shift.
(And it's possible that "x * 5" will become "x << 2 + x", too.)
Definitely go for the expressive version unless you've actually tested
that the obscure version is faster.

(Of course, that doesn't mean the bit-shift operators should never be
used. If you're trying to pack three tiny integers into a single
larger integer, you probably want bit shifts and bitwise or, not
multiplication and addition, even though either would work.)

Code should look like its intent. Warping it around performance is
hardly ever worthwhile.

ChrisA


From tjreedy at udel.edu  Tue Mar  4 00:32:56 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 04 Mar 2014 00:32:56 -0500
Subject: 3.4rc2 and pip on windows
In-Reply-To: <lf2m8g$ouv$1@ger.gmane.org>
References: <lf0ge3$fbv$1@ger.gmane.org> <lf0h42$l88$2@ger.gmane.org>
 <lf2m8g$ouv$1@ger.gmane.org>
Message-ID: <lf3oi5$h9c$1@ger.gmane.org>

On 3/3/2014 2:47 PM, Mark Lawrence wrote:
> On 03/03/2014 00:07, Terry Reedy wrote:
>> On 3/2/2014 6:55 PM, Mark Lawrence wrote:
>>> Trying to install pyttsx, it doesn't strike me as very clever that, as
>>> seen below, you get "Successfully installed pyttsx" despite the syntax
>>> errors and you can't actually do an import.
>>>
>>> c:\Users\Mark\CrossCode>c:\Python34\Scripts\pip3.4.exe install pyttsx
>>> Downloading/unpacking pyttsx
>>>    Downloading pyttsx-1.1.tar.gz
>>>    Running setup.py
>>> (path:C:\Users\Mark\AppData\Local\Temp\pip_build_Mark\pyttsx\setup.py)
>>> egg_info for package pyttsx
>>>
>>> Installing collected packages: pyttsx
>>>    Running setup.py install for pyttsx
>>>        File "C:\Python34\Lib\site-packages\pyttsx\driver.py", line 105
>>>          except Exception, e
>>>                          ^
>>>      SyntaxError: invalid syntax

This is from setup.py


>>> [other syntax errors snipped]
>>>
>>> Successfully installed pyttsx

This is from pip, saying that it successfully downloaded and installed 
the files on your disk, which it did.

>> A bug it seems to me.

After reading the responses on the tracker and here, the bug is in the 
total systen of interaction of multiple parts. It is not a bug for the 
part covered by the tracker.

>>> Cleaning up...
>>>
>>> c:\Users\Mark\CrossCode>py -3.4
>>> Python 3.4.0rc2 (v3.4.0rc2:a300712ed38c, Feb 23 2014, 10:49:04) [MSC
>>> v.1600 32 bit (Intel)] on win32
>>> Type "help", "copyright", "credits" or "license" for more information.
>>>  >>> import pyttsx
>>> Traceback (most recent call last):
>>>    File "<stdin>", line 1, in <module>
>>>    File "C:\Python34\lib\site-packages\pyttsx\__init__.py", line 18, in
>>> <module>
>>>      from engine import Engine
>>>
>>> I've looked at pyttsx in my 3.3 site-packages and it appears that I've
>>> manually run 2to3.  Is this something that could be done automatically
>>> by pip?  Your thoughts please, ladies and gentlemen.
>>
>> I should hope so.

> FTR I raised this as http://bugs.python.org/issue20846 and it was closed
> 11 minutes after I raised it.  I won't say anything else as I'm
> extremely tired and irritable and might well regret it later.

The issue brought to attention that the parts do not work together 
perfectly yet and stimulated some thought and some clarification on what 
needs to be done. I understand the irritation, but sleeping on it and 
letting it go is a good idea.

-- 
Terry Jan Reedy



From steve at pearwood.info  Tue Mar  4 00:35:24 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 05:35:24 GMT
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
Message-ID: <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>

On Tue, 04 Mar 2014 05:37:27 +1100, Chris Angelico wrote:

> On Tue, Mar 4, 2014 at 4:27 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> On Tue, 04 Mar 2014 02:01:47 +1100, Chris Angelico wrote:
>>
>>> This is why it's tricky to put rules in based on type inference. The
>>> programmer's intent isn't in the picture.
>>
>> Of course it is. If I assign 23 to variable x, that signals my intent
>> to assign an int to x. By Occam's razor, it is reasonable to
>> extrapolate that intent to mean "x is an int", rather than "an int, or
>> a list" or "an odd int larger than 7 but smaller than 25", or "any int
>> except 13". Type inference picks the type which involves the fewest
>> additional assumptions. The programmer can always over-ride the type
>> inference by explicitly stating the type.
> 
> Yes, and that's fine for most purposes. The problem isn't the inference,
> the problem is when rules are created based on that kind of guess - when
> the programmer's subsequent actions are governed by a guess the compiler
> takes.
> 
> x = 23 # Compiler goes: Okay, x takes ints. x += 5 # Compiler: No prob,
> int += int --> int x = str(x) # Compiler: NO WAY! str(int) --> str, not
> allowed!
> 
> It's fine and correct to infer that x is an int, x is an int, x is a
> str. It's *not* okay to make the third line a SyntaxError because you
> just put a str into an int variable.

It won't be a Syntax Error, it will be a compile-time Type Error. And, 
yes, it is fine. That's the point of static typing! The tradeoff of being 
able to detect a whole lot of errors *at compile time* is that you give 
up the ability to re-use the same variable for different types in a 
single scope. (You can have an x which is a string elsewhere, just not in 
this scope where it is an int.)

It's okay if you personally prefer the flexibility and freedom of dynamic 
typing. The cost of this choice is that you become responsible for 
writing unit tests that ensure that code behaves safely when given 
unexpected types. If you choose static typing instead, you get a whole 
lot of error checking done at compile time, and likely a lot of compiler 
optimizations. But the cost is that you can't write:

x = 23
x += 5
x = str(x)

and instead have to write:

x = 23
x += 5
s = str(x)


You should, I think, read this:

http://cdsmith.wordpress.com/2011/01/09/an-old-article-i-wrote/


[...]
>> That's not type inference. That's ancient and annoying obligatory type
>> declarations as used by ancient languages with primitive type systems,
>> like Pascal and C.
> 
> And that's exactly what Haskell apparently has, with homogeneous lists
> and no easy way to say that it can take more types.

That Haskell has homogeneous lists is not a property of the type system, 
but a design choice. I'm sure Haskell will also have a tuple or record 
type that allows fields of different types.


> Python's handling is: A list can hold anything.
[...]
> Haskell's handling apparently is: A list/array can hold one thing and
> one thing only. That 'thing' can be a union, but then you need to be
> REALLY explicit about which side is which. 

Yes. 


> It's not possible to
> sub-specify a type (like the "string('a'..'x')" type in Pike that will
> take only strings with nothing but the first 24 lower-case letters - not
> that I've ever needed that), but the compiler can work out everything
> else.

I have not used Haskell enough to tell you whether you can specify 
subtypes. I know that, at least for numeric (integer) types, venerable 
old Pascal allows you to define subtypes based on integer ranges, so I'd 
be surprised if you couldn't do the same thing in Haskell.

The flexibility of the type system -- its ability to create subtypes and 
union types -- is independent of whether it is explicitly declared or 
uses type inference.


> The way I see it, Python's form is fully dynamic and open, Pike's is
> fully dynamic and the programmer's allowed to explicitly close things,
> and Haskell's is rigidly tight. That's not to say that tight is a bad
> thing (it's probably good for learning under), but personally, I'd
> rather have the freedom.

Hey, I'm a Python programmer! You don't have to sell me on the benefits 
of dynamic typing. Before Python, my language of choice was Apple's 
Hyperscript, which is untyped -- everything, and I mean everything, is a 
string in Hyperscript. It works remarkably well, so long as you don't 
care about speed. But even in the late 80s or early 1990s, on single-core 
CPUs running at a piddly 7.8 MHz (compared to about 1000 MHz for desktops 
today), you could get acceptable performance for a remarkable range of 
applications.

But don't be fooled, those benefits aren't free. Static typing has 
benefits too.


-- 
Steven


From steve at pearwood.info  Tue Mar  4 00:53:06 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 05:53:06 GMT
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
Message-ID: <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>

On Tue, 04 Mar 2014 14:46:25 +1100, Chris Angelico wrote:

> That's neat, didn't know that. Is there an efficient way to figure out,
> for any integer N, what its sqrt's CF sequence is? And what about the
> square roots of non-integers - can you represent ?? that way? I suspect,
> though I can't prove, that there will be numbers that can't be
> represented even with an infinite series - or at least numbers whose
> series can't be easily calculated.

Every rational number can be written as a continued fraction with a 
finite number of terms[1]. Every irrational number can be written as a 
continued fraction with an infinite number of terms, just as every 
irrational number can be written as a decimal number with an infinite 
number of digits. Most of them (to be precise: an uncountably infinite 
number of them) will have no simple or obvious pattern.


[1] To be pedantic, written as *two* continued fractions, one ending with 
the term 1, and one with one less term which isn't 1. That is:

    [a; b, c, d, ..., z, 1] == [a; b, c, d, ..., z+1]


Any *finite* CF ending with one can be simplified to use one fewer term. 
Infinite CFs of course don't have a last term.



-- 
Steven


From rustompmody at gmail.com  Tue Mar  4 00:59:03 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 21:59:03 -0800 (PST)
Subject: Functional programming
In-Reply-To: <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <596a3756-808c-4d66-995f-a9db13effb9a@googlegroups.com>

On Tuesday, March 4, 2014 11:05:24 AM UTC+5:30, Steven D'Aprano wrote:
> On Tue, 04 Mar 2014 05:37:27 +1100, Chris Angelico wrote:

> > It's not possible to
> > sub-specify a type (like the "string('a'..'x')" type in Pike that will
> > take only strings with nothing but the first 24 lower-case letters - not
> > that I've ever needed that), but the compiler can work out everything
> > else.

> I have not used Haskell enough to tell you whether you can specify 
> subtypes. I know that, at least for numeric (integer) types, venerable 
> old Pascal allows you to define subtypes based on integer ranges, so I'd 
> be surprised if you couldn't do the same thing in Haskell.

Its a bit murkier. See
http://lambda-the-ultimate.org/node/4771

Especially see the scala choices comment

Also this comment by Peyton Jones is telling

Damas-Milner* is on a cusp: 
Can infer most-general types without any type annotations at all
But virtually any extension destroys this property

from www.cs.nott.ac.uk/~gmh/appsem-slides/peytonjones.ppt

* The functional programming type inference algorithm


From rosuav at gmail.com  Tue Mar  4 01:04:55 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 17:04:55 +1100
Subject: Functional programming
In-Reply-To: <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CAPTjJmoH=4hvw1gQctzTn3kUrOrc+9RUom5-tbQjgbmAyBA_0w@mail.gmail.com>

On Tue, Mar 4, 2014 at 4:35 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Tue, 04 Mar 2014 05:37:27 +1100, Chris Angelico wrote:
>> x = 23 # Compiler goes: Okay, x takes ints. x += 5 # Compiler: No prob,
>> int += int --> int x = str(x) # Compiler: NO WAY! str(int) --> str, not
>> allowed!
>>
>> It's fine and correct to infer that x is an int, x is an int, x is a
>> str. It's *not* okay to make the third line a SyntaxError because you
>> just put a str into an int variable.
>
> It won't be a Syntax Error, it will be a compile-time Type Error. And,
> yes, it is fine. That's the point of static typing! The tradeoff of being
> able to detect a whole lot of errors *at compile time* is that you give
> up the ability to re-use the same variable for different types in a
> single scope. (You can have an x which is a string elsewhere, just not in
> this scope where it is an int.)

Okay, a compile-type type error, same difference. What I'm saying is
that the auto-detection can't know what else you plan to do. If you
explicitly say that this is an int, then yes, that should be
disallowed; if you explicitly say that it's either an int or a float,
then you should be able to have either, but not a string. (C does this
with explicitly tagged unions, usually. Python and Pike do it by
simply allowing multiple types in the same slot.)

> That Haskell has homogeneous lists is not a property of the type system,
> but a design choice. I'm sure Haskell will also have a tuple or record
> type that allows fields of different types.

If it's not the list type, pick some other. It's not uncommon to want
to have a record that has different types (C does this with struct,
C++ has a few more ways to do it); what I'm finding odd is that
whatever goes into it first is specifying for everything else.

> I have not used Haskell enough to tell you whether you can specify
> subtypes. I know that, at least for numeric (integer) types, venerable
> old Pascal allows you to define subtypes based on integer ranges, so I'd
> be surprised if you couldn't do the same thing in Haskell.
>
> The flexibility of the type system -- its ability to create subtypes and
> union types -- is independent of whether it is explicitly declared or
> uses type inference.

I'm not sure how you could have type inference with subtypes. How does
the compiler figure out what subtype of integers is acceptable, such
that it can reject some?

x = 5
x = 7
x = 11
x = 17
x = 27

Should the last one be rejected because it's not prime? How can it
know that I actually wanted that to be int(3..20)? That's why I see
them as connected. All sorts of flexibilities are possible when the
programmer explicitly tells the compiler what the rules are.

> Hey, I'm a Python programmer! You don't have to sell me on the benefits
> of dynamic typing. Before Python, my language of choice was Apple's
> Hyperscript, which is untyped -- everything, and I mean everything, is a
> string in Hyperscript. It works remarkably well, so long as you don't
> care about speed. But even in the late 80s or early 1990s, on single-core
> CPUs running at a piddly 7.8 MHz (compared to about 1000 MHz for desktops
> today), you could get acceptable performance for a remarkable range of
> applications.
>
> But don't be fooled, those benefits aren't free. Static typing has
> benefits too.

For me, that untyped language was REXX. One data type (the string),
and a special feature of variable names to handle what most people
would do with arrays/lists/mappings/dicts/etc/etc/etc. (Or, of course,
you do what you'd presumably do in Hyperscript, and implement an array
of words as a string that you separate on ' '. VX-REXX had a neat
'initializer format' where you simply prefix every element with the
separator - that is to say, the first character of the string is the
separator. It nests perfectly and is pretty convenient to type. A
little obscure for most people, though.) Was also my first taste of
arbitrary-precision arithmetic. C could cream it as long as I didn't
need anything over 2**32 or anything I can't do in a double-precision
float, but I could calculate 200! with clean brute-force code and it'd
work perfectly.

Static and dynamic typing both have their uses. But when I use static
typing, I want to specify the types myself. I'm aware that's a matter
of opinion, but I don't like the idea of the compiler rejecting code
based on inferred types.

ChrisA


From rustompmody at gmail.com  Tue Mar  4 01:20:51 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 3 Mar 2014 22:20:51 -0800 (PST)
Subject: Functional programming
In-Reply-To: <mailman.7695.1393913099.18130.python-list@python.org>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
Message-ID: <c5987af5-fc51-435a-a161-9a258c1f97d6@googlegroups.com>

On Tuesday, March 4, 2014 11:34:55 AM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 4, 2014 at 4:35 PM, Steven D'Aprano wrote:
> > I have not used Haskell enough to tell you whether you can specify
> > subtypes. I know that, at least for numeric (integer) types, venerable
> > old Pascal allows you to define subtypes based on integer ranges, so I'd
> > be surprised if you couldn't do the same thing in Haskell.
> > The flexibility of the type system -- its ability to create subtypes and
> > union types -- is independent of whether it is explicitly declared or
> > uses type inference.

> I'm not sure how you could have type inference with subtypes.

Short answer: You cant [Yeah Some folks dont like my short answers :-) ]

Long answer: See the links I posted above

Intermediate answer:
Types (for a modern FPL) are like math sets except that:
- set-membership is in general hard and in principle undecidable
- type-membership had better be decidable and preferably linear-time if its 
to be part of an implementation (and not a philosophical discussion over a cuppa
chai)
- Which means that...

> Static and dynamic typing both have their uses. But when I use static
> typing, I want to specify the types myself. I'm aware that's a matter
> of opinion, but I don't like the idea of the compiler rejecting code
> based on inferred types.

...Type inference is strictly (aka mathematically) syntax even though
in the implementation, the parsing phase and the type checking/inferencing phase
are sequenced

In short: An important flavor of the FP koolaid is the Damas-Milner
type-inferencing algorithm. Damas-Milner + Subtyping is the recipe for
a severe headache -- An important reason why FP and OOP are incompatible


From rosuav at gmail.com  Tue Mar  4 01:35:12 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 17:35:12 +1100
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CAPTjJmp-iQLL_VypbMqzgHmQHiNQU-hvAgzR-zh32h05av4p4A@mail.gmail.com>

On Tue, Mar 4, 2014 at 4:53 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Tue, 04 Mar 2014 14:46:25 +1100, Chris Angelico wrote:
>
>> That's neat, didn't know that. Is there an efficient way to figure out,
>> for any integer N, what its sqrt's CF sequence is? And what about the
>> square roots of non-integers - can you represent ?? that way? I suspect,
>> though I can't prove, that there will be numbers that can't be
>> represented even with an infinite series - or at least numbers whose
>> series can't be easily calculated.
>
> Every irrational number can be written as a
> continued fraction with an infinite number of terms, just as every
> irrational number can be written as a decimal number with an infinite
> number of digits.

It's easy enough to have that kind of expansion, I'm wondering if it's
possible to identify it directly. To render the decimal expansion of a
square root by the cut-and-try method, you effectively keep dividing
until you find that you're "close enough"; that means you (a) have to
keep the entire number around for each step, and (b) need to do a few
steps to find that the digits aren't changing. But if you can take a
CF (finite or infinite) and do an O(n) transformation on it to produce
that number's square root, then you have an effective means of
representing square roots. Suppose I make a generator function that
represents a fraction:

def one_third():
    while True:
        yield 3

def one_seventh():
    while True:
        yield 1; yield 4; yield 2; yield 8; yield 5; yield 7

I could then make a generator that returns the sum of those two:

def add_without_carry(x, y):
    whiile True:
        yield next(x)+next(y)

Okay, that's broken for nearly any case, but with a bit more sophistication:

def add(x, y):
    prev=None
    nines=0
    while True:
        xx,yy=next(x),next(y)
        tot=xx+yy
        if tot==9:
            nines+=1
            continue
        if tot>9:
            if prev is None: raise OverflowError("exceeds 1.0")
            yield prev+1
            tot-=10
            for _ in range(nines): yield 0
            nines=0
        else:
            if prev is not None: yield prev
        prev=tot

def show(n):
    return ''.join(str(_) for _ in itertools.islice(n,20))

>>> show(add(one_third(),one_seventh()))
'47619047619047619047'
>>> show(add(add(add(one_seventh(),one_seventh()),add(one_seventh(),one_seventh())),add(one_seventh(),one_seventh())))
'85714285714285714285'

In constant space, that will produce the sum of two infinite sequences
of digits. (And it's constant time, too, except when it gets a stream
of nines. Adding three thirds together will produce an infinite loop
as it waits to see if there'll be anything that triggers an infinite
cascade of carries.) Now, if there's a way to do that for square
rooting a number, then the CF notation has a distinct benefit over the
decimal expansion used here. As far as I know, there's no simple way,
in constant space and/or time, to progressively yield more digits of a
number's square root, working in decimal.

ChrisA


From steve at pearwood.info  Tue Mar  4 03:56:33 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 08:56:33 GMT
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
Message-ID: <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>

On Tue, 04 Mar 2014 17:04:55 +1100, Chris Angelico wrote:

> On Tue, Mar 4, 2014 at 4:35 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> On Tue, 04 Mar 2014 05:37:27 +1100, Chris Angelico wrote:
>>> x = 23 # Compiler goes: Okay, x takes ints. x += 5 # Compiler: No
>>> prob, int += int --> int x = str(x) # Compiler: NO WAY! str(int) -->
>>> str, not allowed!
>>>
>>> It's fine and correct to infer that x is an int, x is an int, x is a
>>> str. It's *not* okay to make the third line a SyntaxError because you
>>> just put a str into an int variable.
>>
>> It won't be a Syntax Error, it will be a compile-time Type Error. And,
>> yes, it is fine. That's the point of static typing! The tradeoff of
>> being able to detect a whole lot of errors *at compile time* is that
>> you give up the ability to re-use the same variable for different types
>> in a single scope. (You can have an x which is a string elsewhere, just
>> not in this scope where it is an int.)
> 
> Okay, a compile-type type error, same difference. What I'm saying is
> that the auto-detection can't know what else you plan to do. 

Obviously it can't see the code you haven't written yet, but it can see 
what you *do* do.


> If you
> explicitly say that this is an int, then yes, that should be disallowed;

It's that "explicitly" part that doesn't follow. Having to manage types 
is the most tedious, boring, annoying, *unproductive* part of languages 
like Java, C and Pascal. Almost always, you're telling the compiler stuff 
that it can work out for itself.

In the same way that managing jumps for GOTO has been automated with for 
loops, while, etc., and managing memory has been automated, there's no 
good reason not to allow the compiler to manage types. Dynamically typed 
languages like Python do so at runtime. Type inference simply allows 
statically typed languages to do the same only at compile time.


[...]
>> That Haskell has homogeneous lists is not a property of the type
>> system, but a design choice. I'm sure Haskell will also have a tuple or
>> record type that allows fields of different types.
> 
> If it's not the list type, pick some other. It's not uncommon to want to
> have a record that has different types (C does this with struct, C++ has
> a few more ways to do it); what I'm finding odd is that whatever goes
> into it first is specifying for everything else.

That's because in Haskell the design was made that lists *must* be used 
for homogeneous data. If you read Python documentation from back in the 
1.5 and early 2.x days, there was a *very* strong recommendation that 
lists be used for homogeneous data only and tuples for heterogeneous 
data. This recommendation goes all the way up to Guido.

# Yes
[1, 3, 4, 2, 5, 9]
(1, "hello", None, 3.5)

# No
[1, "hello", None, 3.5]


That is, lists are for collections of data of arbitrary length, tuples 
are for records or structs with dedicated fields.

That convention is a bit weaker these days than it used to be. Tuples now 
have list-like methods, and we have namedtuple for record/struct-like 
objects with named fields. But still, it is normal to use lists with 
homogeneous data, where there is an arbitrary number of "things" with 
different values, but all the same kind of thing.

In the case of Haskell, that's more than a mere convention, it's a rule, 
but that's not terribly different from (say) Pascal where you can have an 
array of integer but not an array of integer-or-real.

The thing is though, how often do you really have a situation where you 
have a bunch of arbitrary data, or unknown length, where you don't know 
what type of data it is? Sure, in the interactive interpreter it is 
useful to be able to write

[1, "spam", None, [], {}, 0.1, set()]

and I write unit tests with that sort of thing all the time:

for obj in list_of_arbitrary_objects:
    self.assertRaises(TypeError, func, obj)

kind of thing. But that doesn't have to be a *list*. It just needs to 
have convenient syntax.


>> I have not used Haskell enough to tell you whether you can specify
>> subtypes. I know that, at least for numeric (integer) types, venerable
>> old Pascal allows you to define subtypes based on integer ranges, so
>> I'd be surprised if you couldn't do the same thing in Haskell.
>>
>> The flexibility of the type system -- its ability to create subtypes
>> and union types -- is independent of whether it is explicitly declared
>> or uses type inference.
> 
> I'm not sure how you could have type inference with subtypes. How does
> the compiler figure out what subtype of integers is acceptable, such
> that it can reject some?

You seem to be under the impression that type inference means "guess what 
the programmer wants", or even "read the programmer's mind". Take this 
example:

> x = 5
> x = 7
> x = 11
> x = 17
> x = 27
> 
> Should the last one be rejected because it's not prime? How can it know
> that I actually wanted that to be int(3..20)? 

It can't, of course, any more than I could, or anyone other than you. But 
if you asked a hundred people what all those values of x had in common, 
93 of them would say "they're all integers", 6 would say "they're all 
positive integers", and 1 would say "they're all positive odd integers".

[Disclaimer: percentages plucked out of thin air.]

No type system can, or should, try to guess whatever bizarre subtype you 
*might* want. ("Only numbers spelled with the letter V.") If you want 
something stupid^W weird^W unusual, it's your responsibility to work 
within the constraints of the programming language to get that, whether 
you are using Python, Pascal or Haskell.


> That's why I see them as
> connected. All sorts of flexibilities are possible when the programmer
> explicitly tells the compiler what the rules are.

And you can still do that, *when you need to*. Assuming the type system 
has a way of specifying "integers that include the letter V", you can 
specify it when you want it. 


> Static and dynamic typing both have their uses. But when I use static
> typing, I want to specify the types myself. I'm aware that's a matter of
> opinion, but I don't like the idea of the compiler rejecting code based
> on inferred types.

Well, so long as you admit it's an irrational preference :-)

The bottom line is, if the compiler rejects code, it's because it has a 
bug. There's *no difference* between the compiler telling you that you 
can't add a string and an int when you've explicitly declared the types, 
and the compiler telling you that you can't add a string and an int when 
it has determined for itself that they are the types because that's all 
that they can be.




-- 
Steven


From francis.moro at gmail.com  Tue Mar  4 04:29:43 2014
From: francis.moro at gmail.com (Francis Moreau)
Date: Tue, 04 Mar 2014 10:29:43 +0100
Subject: Decoding a process output
Message-ID: <lf46bg$5qc$1@ger.gmane.org>

Hi,

In my understanding (I'm relatively new to python), I need to decode any
bytes data provided, in my case, by a shell command (such as findmnt)
started by the subprocess module. The goal of my application is to parse
the command outputs.

My application runs only on linux BTW and should run fine on both python
2.7 and py3k.

My question is when decoding the output bytes data of the external
command, which encoding should I use ?

Should I guess the encoding by inspecting LANG or any LC_* environment
variables ?

Should I force one of those environment variable to a specific value
before running my external command ?

Thanks for any tips.




From bc at freeuk.com  Tue Mar  4 04:41:34 2014
From: bc at freeuk.com (BartC)
Date: Tue, 4 Mar 2014 09:41:34 -0000
Subject: Functional programming
In-Reply-To: <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com><mailman.7612.1393810048.18130.python-list@python.org><4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com><mailman.7633.1393849247.18130.python-list@python.org><3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com><mailman.7641.1393855219.18130.python-list@python.org><216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com><mailman.7644.1393856584.18130.python-list@python.org><0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com><mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <TehRu.7$8R3.4@fx30.am4>

"Steven D'Aprano" <steve+comp.lang.python at pearwood.info> wrote in message
news:5314bb96$0$29985$c3e8da3$5496439d at news.astraweb.com...

> Think about the sort of type declarations you have to do in (say) Pascal,
> and consider how stupid the compiler must be:
>
> function add_one(x: integer):integer;
>  begin
>    add_one := x+1;
>  end;
>
> Given that x is an integer, and that you add 1 (also an integer) to it,
> is it really necessary to tell the compiler that add_one returns an
> integer? What else could the output type be?
>
> This was state of the art back in 1970, but these days, if the compiler
> cannot *at least* infer the type of the return result of a function given
> the argument types, the static type system is too dumb to bother with.

To me that is perfectly reasonable. This kind of language, while it allows
expressions of mixed numeric types, treats each kind of number type as
different: integer and real, even signed and unsigned integer, and there
might be short, medium and long versions of each! And Pascal has an
unlimited number of scalar types too.

The compiler could make a guess at what the intended result might be, based
on a hundred add_one:= assignments, all with a slightly different type on 
the right-hand-side, and perhaps choose a type that encompasses all the 
possibilities (although it might erroneously decide the result is real, 
based on one of those hundred, and use floating point for all of them).

But then someone edits the code, and this time the guess will be different!
For a static language such as this, type-discipline is important. And even
if the compiler gets it right, a human reading the code would have trouble
determining the return type, except in trivial examples like this.

Putting in an explicit return type is the simplest way to go.

-- 
Bartc 



From peacech at gmail.com  Tue Mar  4 04:52:59 2014
From: peacech at gmail.com (Charles Gunawan)
Date: Tue, 4 Mar 2014 01:52:59 -0800 (PST)
Subject: Python 2.7 documentation with readthedocs theme
Message-ID: <0f2da19b-1b8a-4da1-8354-773ff224f734@googlegroups.com>

Hi,

I was just looking into some documentation on readthedocs and I saw that they have a cool new theme. I was wondering how the python documentation will look like with that theme. So after some tinkering I have build python 2.7 CHM documentation with the theme.

If you are wondering too you can look at the chm (http://d-h.st/e1W) or the screenshot (http://imgur.com/7kVzZUt).


From ikorot01 at gmail.com  Tue Mar  4 05:02:17 2014
From: ikorot01 at gmail.com (Igor Korot)
Date: Tue, 4 Mar 2014 02:02:17 -0800
Subject: Logging
Message-ID: <CA+FnnTyg1-uP51KdhgSuriw4cb=KDtFQbt_bESiRM8Bnk8TtUA@mail.gmail.com>

Hi, ALL,
Could someone please explain to me how the code in
http://docs.python.org/2/howto/logging#logging-from-multiple-modules
works?
In particular I'm interested in how the mylib.py knows about the myapp.log.

What I mean is: logging object is not passed to mylib.py, so
essentially it should create a new instance of the logging object.

What am I missing?

But this question comes from the following fact about my application.
I tried to create a logging object which will store the logging
information to the file in the main class. Then I pass this object to
another class constructor and use it in that second class.

Upon running everything is OK, but when the program successfully
finishes, the log file has 0 length.

AFAIU, I'm doing it properly and the example referenced is wrong, yet
the results are completely different.

Thank you for any expplanation.


From mailinglists at vanwingerde.nl  Tue Mar  4 05:33:19 2014
From: mailinglists at vanwingerde.nl (Jaap van Wingerde)
Date: Tue, 4 Mar 2014 10:33:19 +0000
Subject: modification time in Python - Django: datetime != datetime :-(
In-Reply-To: <04659633-e14e-4d5b-90f2-93af04f056be@googlegroups.com>
References: <20140303133541.66fccbbb@lia.custard.shrl.nl>
 <CAPTjJmrp9Ca5zyfo75NKcX_ik0Qi4kOcjhhY6EEWKQ-xJx7KQg@mail.gmail.com>
 <mailman.7646.1393856904.18130.python-list@python.org>
 <04659633-e14e-4d5b-90f2-93af04f056be@googlegroups.com>
Message-ID: <20140304103319.5f8cd8cf@jaap.custard.shrl.nl>

Op 2014-03-03T12:22:48 UTC schreef donarb <donarb at nwlink.com> in het
bericht <Re: modification time in Python - Django: datetime !=
datetime :-(>, ID: <04659633-e14e-4d5b-90f2-93af04f056be at googlegroups.com> het volgende. 

> You're using the months format '%m' when you should be using minutes
> '%M'.

Arrgh: stupid error (snik).

p 2014-03-04T08:11:46 UTC schreef Chris Angelico <rosuav at gmail.com> in
het bericht <Re: modification time in Python - Django: datetime !=
datetime :-(>, ID: <CAPTjJmrz-oq-YLZ_0=jHgj9B1y4s_6bZfN52XMn6Xw10TXE2FQ at mail.gmail.com>
het volgende. 

> Heh! I didn't even notice that. When I tested it, I didn't use
> strftime at all, just looked at gmtime's output.

Op 2014-03-04T08:06:21 UTC schreef Ben Finney <ben+python at benfinney.id.au> in het bericht <Re: modification time in
Python - Django: datetime != datetime :-(>, ID: <85txbfhu0i.fsf at benfinney.id.au> het volgende.

> You're using ?gmtime? to display the Python datetime value, but ?ls?
> will display the time in the local timezone. Do you have a strange
> timezone set?

I only use UTC.

Thanks!!!!

The view.py is now as follows.

...
home_lastmod = strftime('%Y-%m-%dT%H:%M:%SZ',gmtime(os.path.getmtime(os.path.dirname(os.path.realpath(__file__ ))+'/templates/art_index.html')))
...

-- 

Jaap van Wingerde
e-mail: 1234567890 at vanwingerde.nl



From antoon.pardon at rece.vub.ac.be  Tue Mar  4 05:56:07 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 04 Mar 2014 11:56:07 +0100
Subject: Functional programming
In-Reply-To: <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <5315B147.3050002@rece.vub.ac.be>

Op 04-03-14 09:56, Steven D'Aprano schreef:

>
>
>> If you
>> explicitly say that this is an int, then yes, that should be disallowed;
> It's that "explicitly" part that doesn't follow. Having to manage types 
> is the most tedious, boring, annoying, *unproductive* part of languages 
> like Java, C and Pascal. Almost always, you're telling the compiler stuff 
> that it can work out for itself.

In the same way writing unit tests is the most tedious, boring, annoying,
*unproductive* part. Amost always you are giving the program results
it can work out for itself.

-- 

Antoon Pardon



From antoon.pardon at rece.vub.ac.be  Tue Mar  4 06:02:33 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 04 Mar 2014 12:02:33 +0100
Subject: why indentation should be part of the syntax
In-Reply-To: <531480DD.5040204@rece.vub.ac.be>
References: <531480DD.5040204@rece.vub.ac.be>
Message-ID: <5315B2C9.3020709@rece.vub.ac.be>


Op 02-03-14 11:41, Stefan Behnel schreef:
> Haven't seen any mention of it on this list yet, but since it's such an
> obvious flaw in quite a number of programming languages, here's a good
> article on the recent security bug in iOS, which was due to accidentally
> duplicated code not actually being as indented as it looked:
> 
> https://www.imperialviolet.org/2014/02/22/applebug.html
> 
> Stefan
> 

Well I can give an example where accidentally duplicated code can get
you in trouble with python and which would be easily caught in C.
If you accidentally duplicate the first half of a function. Chances
are python will just accept it, because it is unlikely the last line
that was duplicated was an if, for or while line. So your half
duplicated function is probably legal python.

However it is very unlikely that the braces will match so you will
very likely get a compilation error.

IMO the problem with C, is not that indentation is not part of the
language. The problem is that after an if, for or while, you get
the choice between putting either one simple statement or a block.
I doubt you would get this problem in a language like modula2 where
an if, for or while statement is always followed by a block, terminated
with "END". So with modula like syntax the code would have looked like

IF (err := SSLHashSHA1.update(&hashCtx, &signedParams)) != 0 THEN
		goto fail;
		goto fail;
END

which wouldn't have been a problem


Or it might have looked like this

IF (err := SSLHashSHA1.update(&hashCtx, &signedParams)) != 0 THEN
		goto fail;
END
		goto fail;

This would have produced the same problem but it would also have
stood out because the second goto is indented in a place where
it is obvious it doesn't match the program structure.

-- 
Antoon Pardon





From greg.ewing at canterbury.ac.nz  Tue Mar  4 06:05:10 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 05 Mar 2014 00:05:10 +1300
Subject: Working with the set of real numbers
In-Reply-To: <mailman.7696.1393914922.18130.python-list@python.org>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
Message-ID: <bnlqb5F3pcrU1@mid.individual.net>

Chris Angelico wrote:
> In constant space, that will produce the sum of two infinite sequences
> of digits.

It's not constant space, because the nines counter
can grow infinitely large.

-- 
Greg


From alister.ware at ntlworld.com  Tue Mar  4 06:10:34 2014
From: alister.ware at ntlworld.com (Alister)
Date: Tue, 04 Mar 2014 11:10:34 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au>
 <mailman.7663.1393882574.18130.python-list@python.org>
 <87wqgb6imm.fsf@elektro.pacujo.net>
 <mailman.7671.1393885206.18130.python-list@python.org>
Message-ID: <KwiRu.19$Cd2.6@fx19.am4>

On Tue, 04 Mar 2014 09:18:57 +1100, Ben Finney wrote:

> Marko Rauhamaa <marko at pacujo.net> writes:
> 
>> Mark Lawrence <breamoreboy at yahoo.co.uk>:
>>
>> > I'd just like to know why people are so obsessed with identities,
>> > I've never thought to use them in 10+ years of writing Python.  Do I
>> > use the KISS principle too often?
>>
>> Calmly choosing the right tool for the job is not an obsession.
> 
> Persistently banging your head in contradiction to the facts of Python's
> data model, as you have been doing, starts to look very much like
> obsession.

Definition of insanity

Doing the same thing over and over again & expecting different results



-- 
Support staff hung over, send aspirin and come back LATER.


From ian.g.kelly at gmail.com  Tue Mar  4 06:19:59 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 4 Mar 2014 04:19:59 -0700
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <CAPTjJmp-iQLL_VypbMqzgHmQHiNQU-hvAgzR-zh32h05av4p4A@mail.gmail.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <CAPTjJmp-iQLL_VypbMqzgHmQHiNQU-hvAgzR-zh32h05av4p4A@mail.gmail.com>
Message-ID: <CALwzid=zLVO0xokQ3d-BPodst_GhCyqK0+oUHKc3MPzzJuDwKA@mail.gmail.com>

On Mon, Mar 3, 2014 at 11:35 PM, Chris Angelico <rosuav at gmail.com> wrote:
> In constant space, that will produce the sum of two infinite sequences
> of digits. (And it's constant time, too, except when it gets a stream
> of nines. Adding three thirds together will produce an infinite loop
> as it waits to see if there'll be anything that triggers an infinite
> cascade of carries.) Now, if there's a way to do that for square
> rooting a number, then the CF notation has a distinct benefit over the
> decimal expansion used here. As far as I know, there's no simple way,
> in constant space and/or time, to progressively yield more digits of a
> number's square root, working in decimal.

The code for that looks like this:

def cf_sqrt(n):
    """Yield the terms of the square root of n as a continued fraction."""
   m = 0
    d = 1
    a = a0 = floor_sqrt(n)
    while True:
        yield a
        next_m = d * a - m
        next_d = (n - next_m * next_m) // d
        if next_d == 0:
            break
        next_a = (a0 + next_m) // next_d
        m, d, a = next_m, next_d, next_a


def floor_sqrt(n):
    """Return the integer part of the square root of n."""
    n = int(n)
    if n == 0: return 0
    lower = 2 ** int(math.log(n, 2) // 2)
    upper = lower * 2
    while upper - lower > 1:
        mid = (upper + lower) // 2
        if n < mid * mid:
            upper = mid
        else:
            lower = mid
    return lower


The floor_sqrt function is merely doing a simple binary search and
could probably be optimized, but then it's only called once during
initialization anyway.  The meat of the loop, as you can see, is just
a constant amount of integer arithmetic.  If it were desired to halt
once the continued fraction starts to repeat, that would just be a
matter of checking whether the triple (m, d, a) has been seen already.

Going back to your example of adding generated digits though, I don't
know how to add two continued fractions together without evaluating
them.


From ian.g.kelly at gmail.com  Tue Mar  4 06:23:04 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 4 Mar 2014 04:23:04 -0700
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <CALwzid=zLVO0xokQ3d-BPodst_GhCyqK0+oUHKc3MPzzJuDwKA@mail.gmail.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <CAPTjJmp-iQLL_VypbMqzgHmQHiNQU-hvAgzR-zh32h05av4p4A@mail.gmail.com>
 <CALwzid=zLVO0xokQ3d-BPodst_GhCyqK0+oUHKc3MPzzJuDwKA@mail.gmail.com>
Message-ID: <CALwzidkNJVUr+FGhYJ5Q-7t=GhHfgx6CP=zvetHWzh3wnmt16g@mail.gmail.com>

On Tue, Mar 4, 2014 at 4:19 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> def cf_sqrt(n):
>     """Yield the terms of the square root of n as a continued fraction."""
>    m = 0
>     d = 1
>     a = a0 = floor_sqrt(n)
>     while True:
>         yield a
>         next_m = d * a - m
>         next_d = (n - next_m * next_m) // d
>         if next_d == 0:
>             break
>         next_a = (a0 + next_m) // next_d
>         m, d, a = next_m, next_d, next_a

Sorry, all that "next" business is totally unnecessary.  More simply:

def cf_sqrt(n):
    """Yield the terms of the square root of n as a continued fraction."""
    m = 0
    d = 1
    a = a0 = floor_sqrt(n)
    while True:
        yield a
        m = d * a - m
        d = (n - m * m) // d
        if d == 0:
            break
        a = (a0 + m) // d


From steve+comp.lang.python at pearwood.info  Tue Mar  4 06:47:53 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 11:47:53 GMT
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
Message-ID: <5315bd68$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 11:56:07 +0100, Antoon Pardon wrote:

> Op 04-03-14 09:56, Steven D'Aprano schreef:
> 
> 
>>
>>> If you
>>> explicitly say that this is an int, then yes, that should be
>>> disallowed;
>> It's that "explicitly" part that doesn't follow. Having to manage types
>> is the most tedious, boring, annoying, *unproductive* part of languages
>> like Java, C and Pascal. Almost always, you're telling the compiler
>> stuff that it can work out for itself.
> 
> In the same way writing unit tests is the most tedious, boring,
> annoying, *unproductive* part. 

Actually, I like writing unit tests. How do you know what the function 
does until you test it? I'm not a TDD fanatic, but often I write tests 
before I write the code, and there's really nothing nicer than seeing a 
whole lot of failing unit tests suddenly start working.

Well, maybe a nice BLT sandwich, when the bacon is nice and lean and the 
lettuce crisp and the tomato flavourful and not too soggy. But other than 
that, writing unit tests and seeing them pass is great.

On the other hand, writing

    int n, m
    double x, y

and similar three hundred times throughout your program is not terribly 
exciting. Even when it compiles, it doesn't mean it works.

> Amost always you are giving the program 
> results it can work out for itself.

Not even close. I'd like to see the compiler that can work out for itself 
that this function is buggy:

def sine_rule(side_a, side_b, angle_a):
    """Return the angle opposite side_b."""
    return math.sin(side_b/side_a)*angle_a


If you don't remember your Sine Rule from trigonometry, that's okay. 
Trust me, the function is badly wrong. It's rubbish really. But short of 
some really impressive AI coupled with a Mathematica-level of maths 
knowledge, how is the compiler supposed to know that?

Static type testing, while valuable, cannot tell you that the program 
does what you wanted it to do.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Tue Mar  4 06:48:46 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 11:48:46 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au>
 <mailman.7663.1393882574.18130.python-list@python.org>
 <87wqgb6imm.fsf@elektro.pacujo.net>
 <mailman.7671.1393885206.18130.python-list@python.org>
 <KwiRu.19$Cd2.6@fx19.am4>
Message-ID: <5315bd9e$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 11:10:34 +0000, Alister wrote:

> Definition of insanity
> 
> Doing the same thing over and over again & expecting different results

*rolls dice*


:-)



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From jldunn2000 at gmail.com  Tue Mar  4 07:27:55 2014
From: jldunn2000 at gmail.com (loial)
Date: Tue, 4 Mar 2014 04:27:55 -0800 (PST)
Subject: find and replace string in binary file
Message-ID: <01951a7d-2ab3-4203-a9c5-2f79017a980d@googlegroups.com>

How do I read a binary file, find/identify a character string and replace it with another character string and write out to another file?

Its the finding of the string in a binary file that I am not clear on.

Any help appreciated


From rosuav at gmail.com  Tue Mar  4 07:43:53 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 4 Mar 2014 23:43:53 +1100
Subject: Working with the set of real numbers
In-Reply-To: <bnlqb5F3pcrU1@mid.individual.net>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <bnlqb5F3pcrU1@mid.individual.net>
Message-ID: <CAPTjJmruHvWsiSqMtp8E_ujFmOHVA=U00vdoBz9sGCn59ghQ9Q@mail.gmail.com>

On Tue, Mar 4, 2014 at 10:05 PM, Gregory Ewing
<greg.ewing at canterbury.ac.nz> wrote:
> Chris Angelico wrote:
>>
>> In constant space, that will produce the sum of two infinite sequences
>> of digits.
>
>
> It's not constant space, because the nines counter
> can grow infinitely large.

Okay, okay, technically yes. But the counter can go a long way up
before it takes up any additional space, so all that's really saying
is that this has a major flaw with anything that produces a long
stream of nines. It can't tell the difference between
.99999999999999998 and .999999999999999999999999[11] where the 11
suddenly carries and it has to flip it all back.

Anyway, that was like ten minutes' knocking-together work, you can't
expect it to be perfect. I'm amazed it even worked. :)

ChrisA


From python at mrabarnett.plus.com  Tue Mar  4 07:47:09 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 04 Mar 2014 12:47:09 +0000
Subject: Origin of 'self'
In-Reply-To: <7edah9989mdjb9mrnrsh5067np0ihv1jml@4ax.com>
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
 <7edah9989mdjb9mrnrsh5067np0ihv1jml@4ax.com>
Message-ID: <5315CB4D.4030907@mrabarnett.plus.com>

On 2014-03-04 02:09, Dennis Lee Bieber wrote:
> On Sun, 2 Mar 2014 22:16:31 -0800 (PST), Westley Mart?nez
> <anikom15 at gmail.com> declaimed the following:
>
>> I understand that in an object method the first argument in the
>> object itself, called self.  However, it doesn't have to be called
>> self, and can be called anything.  So my question is why is it
>> called self and not this like from C++ and Java.  It's kind of a
>> silly question, but one that I'm curious about nevertheless.
>>
>
> It didn't want to be egotistical (as I recall, M$ VB uses "me")
>
So does AppleScript.

<OT>
In AppleScript a script can refer to the title of a window as "title of
window" or "window's title", and it can refer to the title of its own
window as "title of window of me" or "me's window's title". Consistent,
yes, but bad English.

That's why I prefer a programming language not to be too much like a
natural language. :-)

</OT>


From news at blinne.net  Tue Mar  4 07:55:39 2014
From: news at blinne.net (Alexander Blinne)
Date: Tue, 04 Mar 2014 13:55:39 +0100
Subject: Reference
In-Reply-To: <mailman.7654.1393872546.18130.python-list@python.org>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <mailman.7654.1393872546.18130.python-list@python.org>
Message-ID: <5315cd4b$0$6670$9b4e6d93@newsspool2.arcor-online.net>

Am 03.03.2014 19:48, schrieb Terry Reedy:
> The 'is' operator has three uses, two intended and one not. In
> production code, 'is' tests that an object *is* a particular singular
> object, such as None or a sentinel instance of class object.

Just a bit of statistics on this one from a recent small project:

<13:51:20> alex at firefly$ grep ' is ' *.py | wc
     65     415    3234
<13:51:35> alex at firefly$ grep ' is None' *.py | wc
     43     243    1948
<13:51:40> alex at firefly$ grep ' is not None' *.py | wc
     21     167    1241
<13:51:44> alex at firefly$ grep ' is False' *.py | wc
      1       5      45

No other uses if 'is' found in almost 3 KLOC...


From rosuav at gmail.com  Tue Mar  4 08:01:01 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 00:01:01 +1100
Subject: Functional programming
In-Reply-To: <5315bd68$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <5315bd68$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqgMzA5ckXjPL9k5qfdPiKQiRuW_DNy=nt3wArKAOwHFQ@mail.gmail.com>

On Tue, Mar 4, 2014 at 10:47 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Not even close. I'd like to see the compiler that can work out for itself
> that this function is buggy:
>
> def sine_rule(side_a, side_b, angle_a):
>     """Return the angle opposite side_b."""
>     return math.sin(side_b/side_a)*angle_a
>
>
> If you don't remember your Sine Rule from trigonometry, that's okay.
> Trust me, the function is badly wrong. It's rubbish really.

I'm not entirely sure what it's trying to do, but you're taking the
sine of a ratio. That... seems wrong, gut-feeling-wise. You take the
sine of an angle and get a ratio, or the arcsine of a ratio and get an
angle. Also, trig functions apply only to right triangles, so the
other angle is either going to be 90?-angle_a or 90?, depending on
whether you want the angle opposite the hypotenuse or not.

But it's years since I studied any of that.

ChrisA


From python at mrabarnett.plus.com  Tue Mar  4 08:08:50 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 04 Mar 2014 13:08:50 +0000
Subject: find and replace string in binary file
In-Reply-To: <01951a7d-2ab3-4203-a9c5-2f79017a980d@googlegroups.com>
References: <01951a7d-2ab3-4203-a9c5-2f79017a980d@googlegroups.com>
Message-ID: <5315D062.2000004@mrabarnett.plus.com>

On 2014-03-04 12:27, loial wrote:
> How do I read a binary file, find/identify a character string and
> replace it with another character string and write out to another
> file?
>
> Its the finding of the string in a binary file that I am not clear
> on.
>
> Any help appreciated
>
Read it in chunks and search each chunk (the chunks should be at least
as long as the search string).

You should note that the string you're looking for could be split
across 2 chunks, so when writing the code make sure that you include
some overlap between adjacent chunks (it's best if the overlap is at
least N-1 characters, where N is the length of the search string).


From __peter__ at web.de  Tue Mar  4 08:18:58 2014
From: __peter__ at web.de (Peter Otten)
Date: Tue, 04 Mar 2014 14:18:58 +0100
Subject: find and replace string in binary file
References: <01951a7d-2ab3-4203-a9c5-2f79017a980d@googlegroups.com>
Message-ID: <lf4jrk$95v$1@ger.gmane.org>

loial wrote:

> How do I read a binary file, find/identify a character string and replace
> it with another character string and write out to another file?
> 
> Its the finding of the string in a binary file that I am not clear on.

That's not possible. You have to convert either binary to string or string 
to binary before you can replace. Whatever you choose, you have to know the 
encoding of the file. Consider

#python3
ENCODING = "iso-8859-1"
with open(source, encoding=ENCODING) as infile:
    data = infile.read()
with open(dest, "w", encoding=ENCODING) as outfile:
    outfile.write(data.replace("n?tig", "m?glich"))

If the file is indeed iso-8859-1 this will replace occurrences of the bytes

b'n\xf6tig' with b'm\xf6glich'

But if you were guessing wrong and the file is utf-8 it may contain the 
bytes b'n\xc3\xb6tig' instead which are incorrectly interpreted by your 
script as 'n??tig' and thus left as is.




From python at mrabarnett.plus.com  Tue Mar  4 08:19:54 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 04 Mar 2014 13:19:54 +0000
Subject: Idle thread (Polling) python GUI and saving program state
In-Reply-To: <4034b33f-0cb6-46fa-931c-450834c98d6e@googlegroups.com>
References: <da3d9fc2-91a9-4fd4-a7b9-7c3825e2ca65@googlegroups.com>
 <mailman.7683.1393898784.18130.python-list@python.org>
 <4034b33f-0cb6-46fa-931c-450834c98d6e@googlegroups.com>
Message-ID: <5315D2FA.20903@mrabarnett.plus.com>

On 2014-03-04 02:41, Rolando wrote:> On Monday, March 3, 2014 6:06:22 PM 
UTC-8, MRAB wrote:
 >> On 2014-03-04 01:33, Rolando wrote:
 >>  > I have a GUI with a bunch of cells which is my "View" in the MVC
 >>  > design. The user enters some information in the view and I pass
 >>  > this on to the model so that using the information entered by
 >>  > the user it(model) can do some processing.
 >>  >
 >>  > I have coded up my model as a state machine. Wherein, once a
 >>  > function is complete it switches to the next state and so on.
 >>  >
 >>  > I want to know how do I save the program state between restarts.
 >>  > Basically, I'm trying to handle a scenario wherein if someone
 >>  > closes the program. The next time someone starts it up, it
 >>  > should start from where it left off (both the view and model)
 >>  >
 >> When the user closes the window (you don't say what you're using for
 >> the GUI, but there should be a way of detecting when window closes),
 >> save the necessary info to a file using, say, the 'json' module. You
 >> can then reload the info from the file when the program is
 >< restarted.
 >>
 >>  > Also, I want to setup a poll method where once in a while I can
 >>  > poll each cell to know the state it is in. How do I do this? I
 >>  > don't want my GUI to hang when I'm doing anything. It will be
 >>  > great if someone could help. Thanks!
 >>  >
 >> Can the model run continuously? If so, you should run it in its own
 >> (background) thread and the GUI in the main thread and communicate
 >> with the model's thread via, say, a queue (for that use the 'queue'
 >> module).
 >
 > I'm using wxPython for my GUI. I have tried running the model thread 
in the background. But how will I save the state if the whole model is 
running on a thread? When the program is restarted I want the program to 
continue from the same state where it left off for each cell. I was 
thinking of having an idle thread that calls a poll method which polls 
all the cells and checks what each one is doing. But, I don't know how 
to do that. I'm confused.
 >
Please read this:

https://wiki.python.org/moin/GoogleGroupsPython

because Gmail is formatting your email badly, making it harder to read.


When the front-end wants to quit, it tells the back-end and then waits
for it to terminate before itself quitting.

When the back-end receives the message that it should quit, it saves
its state and terminates.

When the front-end starts up again, it starts the back-end.

When the back-end starts, it load the state and runs.



From bc at freeuk.com  Tue Mar  4 08:30:04 2014
From: bc at freeuk.com (BartC)
Date: Tue, 4 Mar 2014 13:30:04 -0000
Subject: Functional programming
In-Reply-To: <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com><mailman.7612.1393810048.18130.python-list@python.org><4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com><mailman.7633.1393849247.18130.python-list@python.org><3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com><mailman.7641.1393855219.18130.python-list@python.org><216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com><mailman.7644.1393856584.18130.python-list@python.org><0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com><mailman.7647.1393858917.18130.python-list@python.org><5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com><mailman.7651.1393871851.18130.python-list@python.org><5315661c$0$2923$c3e8da3$76491128@news.astraweb.com><mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <XzkRu.27$O_6.17@fx04.am4>

"Steven D'Aprano" <steve at pearwood.info> wrote in message
news:53159540$0$2923$c3e8da3$76491128 at news.astraweb.com...

> It's that "explicitly" part that doesn't follow. Having to manage types
> is the most tedious, boring, annoying, *unproductive* part of languages
> like Java, C and Pascal. Almost always, you're telling the compiler stuff
> that it can work out for itself.

Isn't creating classes in Python similar to creating types elsewhere?

> In the same way that managing jumps for GOTO has been automated with for
> loops, while, etc., and managing memory has been automated, there's no
> good reason not to allow the compiler to manage types. Dynamically typed
> languages like Python do so at runtime. Type inference simply allows
> statically typed languages to do the same only at compile time.

Eliminating 'goto' is simple code-generation logic; type inference is more
of an art.

But declaring variables is not just about specifying a type; it registers
the name too so that misspelled names can be picked up very early rather
than at runtime (and that's if you're lucky).

> # Yes
> [1, 3, 4, 2, 5, 9]
> (1, "hello", None, 3.5)
>
> # No
> [1, "hello", None, 3.5]
>
>
> That is, lists are for collections of data of arbitrary length, tuples
> are for records or structs with dedicated fields.
>
> That convention is a bit weaker these days than it used to be. Tuples now
> have list-like methods, and we have namedtuple for record/struct-like
> objects with named fields.

(Aren't tuples immutable? They wouldn't work well for records then, because 
it would be impossible to change a field of a record.)

-- 
Bartc 



From rosuav at gmail.com  Tue Mar  4 08:47:54 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 00:47:54 +1100
Subject: Functional programming
In-Reply-To: <XzkRu.27$O_6.17@fx04.am4>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
Message-ID: <CAPTjJmoRiSqcEybozsBVSJkC89XJdK1fYX4eKSwuxmoQAyy2dA@mail.gmail.com>

On Wed, Mar 5, 2014 at 12:30 AM, BartC <bc at freeuk.com> wrote:
> But declaring variables is not just about specifying a type; it registers
> the name too so that misspelled names can be picked up very early rather
> than at runtime (and that's if you're lucky).

The two are separate. I don't know of any language that lets you
declare a type without catching the names, but there's certainly the
other way around (ECMAScript just has "var x, y, z"). It'd be
theoretically possible to have a Python-style "variable inference"
system (if I can call it that - the rules of "if you assign to it and
don't declare it as global/nonlocal, it's local") coupled with an
optional type declaration system; if you don't declare, then it can
hold anything. I just don't know of any language that does it.

>> That convention is a bit weaker these days than it used to be. Tuples now
>> have list-like methods, and we have namedtuple for record/struct-like
>> objects with named fields.
>
> (Aren't tuples immutable? They wouldn't work well for records then, because
> it would be impossible to change a field of a record.)

They are, including namedtuples. But an object() can be used that way,
if you want.

ChrisA


From breamoreboy at yahoo.co.uk  Tue Mar  4 09:05:44 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 04 Mar 2014 14:05:44 +0000
Subject: Functional programming
In-Reply-To: <XzkRu.27$O_6.17@fx04.am4>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com><mailman.7612.1393810048.18130.python-list@python.org><4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com><mailman.7633.1393849247.18130.python-list@python.org><3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com><mailman.7641.1393855219.18130.python-list@python.org><216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com><mailman.7644.1393856584.18130.python-list@python.org><0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com><mailman.7647.1393858917.18130.python-list@python.org><5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com><mailman.7651.1393871851.18130.python-list@python.org><5315661c$0$2923$c3e8da3$76491128@news.astraweb.com><mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
Message-ID: <lf4mji$b7h$1@ger.gmane.org>

On 04/03/2014 13:30, BartC wrote:
>
> But declaring variables is not just about specifying a type; it registers
> the name too so that misspelled names can be picked up very early rather
> than at runtime (and that's if you're lucky).
>

I've said before that this, to me, is one of the major downsides of 
dynamic typing.  Once a statically typed language has been compiled the 
programmer can head down to the pub.  The programmer using dynamically 
typed languages has to hang around doing long, boring, tedious testing. 
  Unless they're using an IDE like Pydev and have Pylint turned on so it 
picks up errors as they type, in which case they can also head down to 
the pub.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Tue Mar  4 09:06:20 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 01:06:20 +1100
Subject: Reference
In-Reply-To: <5315cd4b$0$6670$9b4e6d93@newsspool2.arcor-online.net>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <mailman.7654.1393872546.18130.python-list@python.org>
 <5315cd4b$0$6670$9b4e6d93@newsspool2.arcor-online.net>
Message-ID: <CAPTjJmqqpEj1NQaG3ao875CHS1nf-V_KSbyK12nK4PuxXmFbhw@mail.gmail.com>

On Tue, Mar 4, 2014 at 11:55 PM, Alexander Blinne <news at blinne.net> wrote:
> Am 03.03.2014 19:48, schrieb Terry Reedy:
>> The 'is' operator has three uses, two intended and one not. In
>> production code, 'is' tests that an object *is* a particular singular
>> object, such as None or a sentinel instance of class object.
>
> Just a bit of statistics on this one from a recent small project:
>
> <13:51:20> alex at firefly$ grep ' is ' *.py | wc
>      65     415    3234
> <13:51:35> alex at firefly$ grep ' is None' *.py | wc
>      43     243    1948
> <13:51:40> alex at firefly$ grep ' is not None' *.py | wc
>      21     167    1241
> <13:51:44> alex at firefly$ grep ' is False' *.py | wc
>       1       5      45
>
> No other uses if 'is' found in almost 3 KLOC...

Lemme spin you up a different way of doing it, which actually looks
for the operators.

https://github.com/Rosuav/ExceptExpr/blob/master/find_except_expr.py

Run across the Python stdlib, that tells me there are 4040 uses of
is/is not, of which 16 compare against False, 18 against True (see?
Python has a bias for truth above falsehood!), and 3386 against None.
The other 620 are probably mostly sentinel objects, but I didn't look
at them.

ChrisA


From rosuav at gmail.com  Tue Mar  4 09:17:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 01:17:43 +1100
Subject: Functional programming
In-Reply-To: <lf4mji$b7h$1@ger.gmane.org>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4> <lf4mji$b7h$1@ger.gmane.org>
Message-ID: <CAPTjJmquguDORm08dPZow=8CRCAvsBot46ae3GrXfytCaF+96w@mail.gmail.com>

On Wed, Mar 5, 2014 at 1:05 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> On 04/03/2014 13:30, BartC wrote:
>>
>>
>> But declaring variables is not just about specifying a type; it registers
>> the name too so that misspelled names can be picked up very early rather
>> than at runtime (and that's if you're lucky).
>>
>
> I've said before that this, to me, is one of the major downsides of dynamic
> typing.  Once a statically typed language has been compiled the programmer
> can head down to the pub.  The programmer using dynamically typed languages
> has to hang around doing long, boring, tedious testing.  Unless they're
> using an IDE like Pydev and have Pylint turned on so it picks up errors as
> they type, in which case they can also head down to the pub.

Type declarations are orthogonal to that. ECMAScript, as mentioned,
just has 'var'. If it didn't have the implicit variables rule
(anything not explicitly declared goes onto the primary object), it'd
give you exactly that functionality, without any type checking at all.

And there's not "static" and "dynamic". It's a spectrum. Each time you
move one direction, you gain a set of potential bugs that the language
can detect; each time you move the other direction, you save on
keyboarding. But at no time do you truly get away from the need to
test, because anything non-trivial can't be proven by the language
anyway.

ChrisA


From steve+comp.lang.python at pearwood.info  Tue Mar  4 09:25:15 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 14:25:15 GMT
Subject: OT Sine Rule [was Re: Functional programming]
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <5315bd68$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7707.1393938071.18130.python-list@python.org>
Message-ID: <5315e24a$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Wed, 05 Mar 2014 00:01:01 +1100, Chris Angelico wrote:

> On Tue, Mar 4, 2014 at 10:47 PM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> Not even close. I'd like to see the compiler that can work out for
>> itself that this function is buggy:
>>
>> def sine_rule(side_a, side_b, angle_a):
>>     """Return the angle opposite side_b.""" return
>>     math.sin(side_b/side_a)*angle_a
>>
>>
>> If you don't remember your Sine Rule from trigonometry, that's okay.
>> Trust me, the function is badly wrong. It's rubbish really.
> 
> I'm not entirely sure what it's trying to do, 

The Sine Rule applies to any triangle, right-angled or not. I'm not going 
to try to draw an ASCII-art triangle here, so you just have to imagine 
one. Label the three sides "a", "b" and "c". Now label the angle opposite 
each side as "A", "B" and "C", so angle A is opposite side a, and so 
forth. The Sine Rule, or Law of Sines, tells us that the ratio of the 
length of a side and the sine of the angle opposite that side is constant 
for any triangle. That is:

a/sin(A) == b/sin(B) == c/sin(C)


Given any two sides and one corresponding angle, let's say a, b and A, 
you can calculate the other angle B. The correct formula would be:

B = asin( sin(A)*b/a )

which is not what my bogus function does.


> but you're taking the sine
> of a ratio. That... seems wrong, gut-feeling-wise. 

Well of course it's wrong. Given the intended geometric meanings of the 
function parameters, the quantity calculated is meaningless. But 
mathematically, it's okay to calculate the sine of a ratio of two other 
quantities. It's just a number. These even a whole lot of double-angle 
formulae that allow you to calculate sin(2*x) given sin(x), or sin(x/2) 
given sin(x), etc.

But, giving that ratio physical or geometric meaning is another story, 
and in this case the semantics of the function is entirely bogus. That 
was my point -- the compiler cannot possibly tell what the function is 
intended to do, it can only check that it is self-consistent.


> You take the sine of
> an angle and get a ratio, or the arcsine of a ratio and get an angle.
> Also, trig functions apply only to right triangles, 

Not quite. Or to put it another way, not at all :-)

Trig functions are *defined* in terms of right-angled triangles, but 
(say) the sine of 30? is 0.5 regardless of whether that 30? angle is in a 
right-angled triangle, an acute triangle or an obtuse triangle. 30? is 
30? regardless of what the rest of the triangle is doing.



Ask-me-about-versine-and-haversine-ly y'rs,

-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Tue Mar  4 09:27:05 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 14:27:05 GMT
Subject: Origin of 'self'
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
 <7edah9989mdjb9mrnrsh5067np0ihv1jml@4ax.com>
 <mailman.7706.1393937237.18130.python-list@python.org>
Message-ID: <5315e2b9$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 12:47:09 +0000, MRAB wrote:

> In AppleScript a script can refer to the title of a window as "title of
> window" or "window's title", and it can refer to the title of its own
> window as "title of window of me" or "me's window's title". Consistent,
> yes, but bad English.
> 
> That's why I prefer a programming language not to be too much like a
> natural language. :-)

But the problem with that is not that it is too much like a natural 
language, but too little like a natural language.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From python.list at tim.thechases.com  Tue Mar  4 09:37:21 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Tue, 4 Mar 2014 08:37:21 -0600
Subject: OT Sine Rule [was Re: Functional programming]
In-Reply-To: <5315e24a$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <5315bd68$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7707.1393938071.18130.python-list@python.org>
 <5315e24a$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <20140304083721.67f81d5d@bigbox.christie.dr>

On 2014-03-04 14:25, Steven D'Aprano wrote:
> Ask-me-about-versine-and-haversine-ly y'rs,

More interested in a karosine, cuisine, and a limousine. ;-)

-tkc




From breamoreboy at yahoo.co.uk  Tue Mar  4 09:42:23 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 04 Mar 2014 14:42:23 +0000
Subject: OT Sine Rule [was Re: Functional programming]
In-Reply-To: <20140304083721.67f81d5d@bigbox.christie.dr>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <5315bd68$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7707.1393938071.18130.python-list@python.org>
 <5315e24a$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <20140304083721.67f81d5d@bigbox.christie.dr>
Message-ID: <lf4oo8$2r6$1@ger.gmane.org>

On 04/03/2014 14:37, Tim Chase wrote:
> On 2014-03-04 14:25, Steven D'Aprano wrote:
>> Ask-me-about-versine-and-haversine-ly y'rs,
>
> More interested in a karosine, cuisine, and a limousine. ;-)
>
> -tkc
>
>

What do you get if you differentiate versines, haversines, karosines, 
cuisines and limosines?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From steve+comp.lang.python at pearwood.info  Tue Mar  4 09:55:32 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 14:55:32 GMT
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
 <mailman.7713.1393941971.18130.python-list@python.org>
Message-ID: <5315e963$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 14:05:44 +0000, Mark Lawrence wrote:

> Once a statically typed language has been compiled the programmer can
> head down to the pub.

"It compiles? Quick! Ship it!"

Well, that certainly explains the quality of some programs...




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From invalid at invalid.invalid  Tue Mar  4 09:59:51 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Tue, 4 Mar 2014 14:59:51 +0000 (UTC)
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <bnkcn8FphikU1@mid.individual.net>
 <mailman.7673.1393885927.18130.python-list@python.org>
Message-ID: <lf4pp7$54n$1@reader1.panix.com>

On 2014-03-03, Ben Finney <ben+python at benfinney.id.au> wrote:
> Gregory Ewing <greg.ewing at canterbury.ac.nz> writes:
>
>> Just because the compiler *can* infer the return type doesn't
>> necessarily mean it *should*. When I was playing around with
>> functional languages, I ended up adopting the practice of always
>> declaring the types of my functions, because it helps the *human*
>> reader.
>
> Sure. In a duck-typed language like Python, it is still helpful to the
> human reader to document the *meaning* of each parameter, beyond what is
> indicated by the name. We have reStructuredText and docstrings for this
> purpose.
>
>     def frobnicate(flang, splets, queeble=False):
>         """ Righteously frobnicate the flang.
>
>             :param flang: A file-like object, opened for reading.
>             :param splets: A sequence of unprocessed Splet instances.
>             :param queeble: If ``True``, re-vitrify the flang during
>                 frobnication.
>             :return: A new list of processed Splet instances.
>
>             The flang is frobnicated according to the Weebly-Ruckford
>             algorithm.
>
>             """
>         for line in flang:

That's fine, if the comments are correct.  

I'm currently working with a library of third party code that was
internally documented like that (though in a different language, with
a slightly different comment formatting). Then they run it through
something (Doxygen?) to produce a giant .CHM file that's pretty much
useless to those of us running Linux.  It turns out it's just as well
I can't read a CHM file: the documentation in the comments is wrong
often enough that I've learned it's best to ignore it completely.
Sometimes the number of parameters and their names don't even match up
with the comments. Sometimes the "docstring" is from a completely
different function which was apparently cut/pasted and then reworked
to do something else.

After a couple decades of working in software development, I've
decided that comments like that are not correct often enough to be
useful. You've got to reverse-engineer the code if there's no such
comment.  If there _is_ a comment, you have to reverse-engineer the
code to see of the comment is accurate.

-- 
Grant Edwards               grant.b.edwards        Yow! I'm young ... I'm
                                  at               HEALTHY ... I can HIKE
                              gmail.com            THRU CAPT GROGAN'S LUMBAR
                                                   REGIONS!


From rosuav at gmail.com  Tue Mar  4 10:06:11 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 02:06:11 +1100
Subject: OT Sine Rule [was Re: Functional programming]
In-Reply-To: <5315e24a$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <5315bd68$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7707.1393938071.18130.python-list@python.org>
 <5315e24a$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmoE4yyf85Fsh_K4jhvtKVmROB_26SvEzb4c608Yo=fq6Q@mail.gmail.com>

On Wed, Mar 5, 2014 at 1:25 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
>
> The Sine Rule, or Law of Sines, tells us that the ratio of the
> length of a side and the sine of the angle opposite that side is constant
> for any triangle. That is:
>
> a/sin(A) == b/sin(B) == c/sin(C)

Oh! Right. Now I remember. Yeah. Still, it looks wrong to... well,
what I said next:

> On Wed, 05 Mar 2014 00:01:01 +1100, Chris Angelico wrote:
>> but you're taking the sine
>> of a ratio. That... seems wrong, gut-feeling-wise.
>
> Well of course it's wrong. Given the intended geometric meanings of the
> function parameters, the quantity calculated is meaningless. But
> mathematically, it's okay to calculate the sine of a ratio of two other
> quantities. It's just a number. These even a whole lot of double-angle
> formulae that allow you to calculate sin(2*x) given sin(x), or sin(x/2)
> given sin(x), etc.

What I meant there was "ratio of side lengths". The definition of sine
is that, in a right triangle, the ratio of the lengths of the side
opposite an angle and the hypotenuse is the sine of that angle. So I
consider sine to be a function that takes an angle and returns a
side-length-ratio, and arcsine does the reverse. It's like asking for
the length of an integer and getting back a string - it just looks
wrong. The sine of double an angle makes sense - it's still an angle.
You don't multiply an angle by a side length, you don't take the sine
of a number of meters per second, and you don't calculate the number
of parsecs it takes you to get to Kessel. The units are just wrong.
Maybe there's some specific situation where that makes sense, but I'd
call it "formula smell". And note that your corrected form still
applies the functions the way I describe - the units are maintained.
(Technically the sine of an angle is a pure number, a straight ratio.
I'm not sure that "pure number" is a unit - it's kinda the absence of
any unit - but that's still something to be maintained.)

> But, giving that ratio physical or geometric meaning is another story,
> and in this case the semantics of the function is entirely bogus. That
> was my point -- the compiler cannot possibly tell what the function is
> intended to do, it can only check that it is self-consistent.

Right. It's a consequence of a type system that distinguishes floating
point from string, but not angle_in_degrees from length_in_meters.
It's theoretically possible to build a type system that's like that
(sometimes you can subclass to do that, and create explicit operations
only), but I've never really felt the need to. But that's the theory
behind some forms of Hungarian notation - identifying a "data type"
concept that's broader than the compiler knows.

>> You take the sine of
>> an angle and get a ratio, or the arcsine of a ratio and get an angle.
>> Also, trig functions apply only to right triangles,
>
> Not quite. Or to put it another way, not at all :-)
>
> Trig functions are *defined* in terms of right-angled triangles, but
> (say) the sine of 30? is 0.5 regardless of whether that 30? angle is in a
> right-angled triangle, an acute triangle or an obtuse triangle. 30? is
> 30? regardless of what the rest of the triangle is doing.

Yes indeed. Like I said, I'm a bit rusty on all that, and forgot about
the ways of using them in non-right triangles :) But that 0.5 doesn't
have intrinsic meaning if you don't have a right triangle around it;
it needs something else to give it useful meaning, like another
angle's sine.

ChrisA


From rosuav at gmail.com  Tue Mar  4 10:13:03 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 02:13:03 +1100
Subject: Functional programming
In-Reply-To: <5315e963$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
 <mailman.7713.1393941971.18130.python-list@python.org>
 <5315e963$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqSfU_28jdonnDeqPZJO+zjpMWXGrBAJwvpKf0ZJVHyNg@mail.gmail.com>

On Wed, Mar 5, 2014 at 1:55 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Tue, 04 Mar 2014 14:05:44 +0000, Mark Lawrence wrote:
>
>> Once a statically typed language has been compiled the programmer can
>> head down to the pub.
>
> "It compiles? Quick! Ship it!"
>
> Well, that certainly explains the quality of some programs...

It explains the quality of other programs too. They were written after
the programmer came back from the pub.

*ducks for cover*

ChrisA


From malaclypse2 at gmail.com  Tue Mar  4 10:19:22 2014
From: malaclypse2 at gmail.com (Jerry Hill)
Date: Tue, 4 Mar 2014 10:19:22 -0500
Subject: Reference
In-Reply-To: <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CADwdpybfBTEq62KDXFPNwE9Wr9T=9pUDK=KMw94MofrJwGHdVQ@mail.gmail.com>

On Mon, Mar 3, 2014 at 11:52 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> If your intention is to treat None as a singleton sentinel, not as a
> value, then you ought to use "is" to signal that intention, rather than
> using == even if you know that there won't be any false positives.

In all of the years I've been on this list, I don't think I've seen
more than one or two cases of someone deliberately treating None as a
singleton sentinel.  In most cases, they're either checking the return
value from a function or using it as a default argument to a function
to force some default behavior when no parameter is passed.  I'm
pretty sure you're going to say that the latter use is exactly where
you should us 'is' instead of '=='.  Respectfully, I disagree.

For a beginning python user, identity checking is an attractive
nuisance. The only time most beginners should use it is when comparing
to None.  But, as soon as they are taught that there are two
comparison operators, I start to see 'is' cropping up in more and more
places where they ought to use '=='.  And the problem is that
sometimes it works for them, and sometimes it doesn't.  Sure, students
eventually need to understand the difference between identity and
equality.  My problem is that by enshrining in python custom that the
only correct way to compare to None is with 'is', we have to explain
that concept way early in the teaching process.  I can't count the
number of times that a thread has completely derailed into identity vs
equality, then into interning of strings and small integers, and
suddenly the thread is 40 messages long, and no one has actually
talked about the code that was originally posted beyond that issue.
In approximately zero cases, have I seen code where 'is' versus '=='
actually made any difference, except where the 'is' is wrong.  I've
also never seen the supposedly ever-present boogie man of an object
that mistakenly compares equal to None, much less seen that object
passed to functions with None-based sentinels.

I feel like 'is' is an operator that ought to be saved for an advanced course.

Out of curiosity, do you think we should be doing truth checking with
'is'?  True and False are singletons, and it seems to me that the
justification for idenity versus equality should be just as strong
there, but I don't think I've ever seen anyone even suggest that.

-- 
Jerry


From steve+comp.lang.python at pearwood.info  Tue Mar  4 10:18:24 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 15:18:24 GMT
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
Message-ID: <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 13:30:04 +0000, BartC wrote:

> "Steven D'Aprano" <steve at pearwood.info> wrote in message
> news:53159540$0$2923$c3e8da3$76491128 at news.astraweb.com...
> 
>> It's that "explicitly" part that doesn't follow. Having to manage types
>> is the most tedious, boring, annoying, *unproductive* part of languages
>> like Java, C and Pascal. Almost always, you're telling the compiler
>> stuff that it can work out for itself.
> 
> Isn't creating classes in Python similar to creating types elsewhere?

Depends on the type: I suppose you can draw an analogy between records or 
structs and classes with no methods.

But I'm not talking about creating types, I'm talking about type 
declarations.

int x=2;  # 2 is an int? Who would have guessed!


>> In the same way that managing jumps for GOTO has been automated with
>> for loops, while, etc., and managing memory has been automated, there's
>> no good reason not to allow the compiler to manage types. Dynamically
>> typed languages like Python do so at runtime. Type inference simply
>> allows statically typed languages to do the same only at compile time.
> 
> Eliminating 'goto' is simple code-generation logic; type inference is
> more of an art.

Type inference is nothing like an art. It's a mathematically provable 
correct algorithm from the lambda calculus.

http://en.wikipedia.org/wiki/Hindley%E2%80%93Milner

Unfortunately the wikipedia page above appears to be complete 
gobbledygook if you aren't an expert in the lambda calculus, which I 
certainly am not, so I'm not even going to try to explain how it works. 
But there is no *guessing* involved, no heuristics which only sometimes 
work. There are certain assumptions involved, e.g. that the type of 
something is, in the absence of a declaration otherwise, the *most* 
general thing it could be (e.g. "it's an integer" rather than "it's an 
integer between 3 and 27"). But they're reasonable, practical assumptions.


> But declaring variables is not just about specifying a type; it
> registers the name too so that misspelled names can be picked up very
> early rather than at runtime (and that's if you're lucky).

You don't need to have static typing to have declared variables. The two 
are independent. E.g. one might have a system like Python, except you 
have to declare your variables before using them:

global x
local a
a = x+1
...

Or a system like (ancient) BASIC, where the type of the variable is given 
by the name. E.g. X is a numeric variable, and X$ is a string variable. 
There's no need for a separate declaration, because the presence or 
absence of the $ sign tells the interpreter whether it is a number or 
string variable. Perl, PHP and many other languages also use sigils.

Having to declare variables, and having to declare their type, are 
independent.


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From python.list at tim.thechases.com  Tue Mar  4 10:21:32 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Tue, 4 Mar 2014 09:21:32 -0600
Subject: OT Sine Rule [was Re: Functional programming]
In-Reply-To: <lf4oo8$2r6$1@ger.gmane.org>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <5315bd68$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7707.1393938071.18130.python-list@python.org>
 <5315e24a$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <20140304083721.67f81d5d@bigbox.christie.dr>
 <lf4oo8$2r6$1@ger.gmane.org>
Message-ID: <20140304092132.523e6440@bigbox.christie.dr>

On 2014-03-04 14:42, Mark Lawrence wrote:
> What do you get if you differentiate versines, haversines,
> karosines, cuisines and limosines?

Well, with cuisines, you can usually differentiate by seasoning:
your Tex/Mex is spicier and tends to have chili & cumin, while your
Indian tends to lean more towards the garam masala.

With your limosines, you have stretch and non-stretch, and some are
these crazy contraptions made out of Hummers or buses rather than
luxury sedans.

And if I could spell "kerosine" instead of "karosine", I guess they
would differentiate from other hydrocarbons by the length of the
carbon chain. ;-)

-tkc




From juraj.ivancic at gmail.com  Tue Mar  4 10:23:32 2014
From: juraj.ivancic at gmail.com (=?ISO-8859-2?Q?Juraj_Ivan=E8i=E6?=)
Date: Tue, 04 Mar 2014 16:23:32 +0100
Subject: how to get bytes from bytearray without copying
In-Reply-To: <CALwzidncPvJS_aPJENre2HfOvV_PoY8mSV4PGA+i8FcwYPFc=A@mail.gmail.com>
References: <lf0h3g$m7r$1@ger.gmane.org>
 <CALwzidncPvJS_aPJENre2HfOvV_PoY8mSV4PGA+i8FcwYPFc=A@mail.gmail.com>
Message-ID: <lf4r5e$756$1@ger.gmane.org>

On 3.3.2014. 2:27, Ian Kelly wrote:

> Python 3.3 has a C API function to create a memoryview for a char*,
> that can be made read-only.
>
>      http://docs.python.org/3/c-api/memoryview.html#PyMemoryView_FromMemory
>
> I don't see a way to do what you want in pure Python, apart from
> perhaps writing an elaborate proxy class that would just be a poor
> man's memoryview.  Or you could bite the bullet and copy everything
> once at the start to create a bytes object, and then never have to
> worry about it again.

Just for reference, it is doable in pure Python, with ctypes help:

pydll = ctypes.cdll.LoadLibrary("python{}{}".format(
     sys.version_info.major, sys.version_info.minor))

def ro_memoryview_from_bytearray(buffer):
     assert isinstance(buffer, bytearray)
     ptr = ctypes.c_char_p(pydll.PyByteArray_AsString(
         ctypes.py_object(buffer)))
     mv_id = pydll.PyMemoryView_FromMemory(ptr, len(buffer), 0)
     return ctypes.cast(mv_id, py_object).value

Note that this is just the jist, in real code I added safeguards to 
prevent misuse of the (temporary) memoryview.




From steve+comp.lang.python at pearwood.info  Tue Mar  4 10:22:52 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 15:22:52 GMT
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <bnkcn8FphikU1@mid.individual.net>
 <mailman.7673.1393885927.18130.python-list@python.org>
 <lf4pp7$54n$1@reader1.panix.com>
Message-ID: <5315efcc$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 14:59:51 +0000, Grant Edwards wrote:

> After a couple decades of working in software development, I've decided
> that comments like that are not correct often enough to be useful.
> You've got to reverse-engineer the code if there's no such comment.  If
> there _is_ a comment, you have to reverse-engineer the code to see of
> the comment is accurate.

http://import-that.dreamwidth.org/956.html




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Tue Mar  4 10:25:57 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 02:25:57 +1100
Subject: Reference
In-Reply-To: <CADwdpybfBTEq62KDXFPNwE9Wr9T=9pUDK=KMw94MofrJwGHdVQ@mail.gmail.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <CADwdpybfBTEq62KDXFPNwE9Wr9T=9pUDK=KMw94MofrJwGHdVQ@mail.gmail.com>
Message-ID: <CAPTjJmorGc83tHebvn_1Kf35fZSkgLsgOqfqaB-wOE21OeYvtA@mail.gmail.com>

On Wed, Mar 5, 2014 at 2:19 AM, Jerry Hill <malaclypse2 at gmail.com> wrote:
> Out of curiosity, do you think we should be doing truth checking with
> 'is'?  True and False are singletons, and it seems to me that the
> justification for idenity versus equality should be just as strong
> there, but I don't think I've ever seen anyone even suggest that.

Normal truth testing is done like this:

if cond:

This isn't truth testing, this is checking the identity of what's in cond:

if cond is True:

And that's specifically testing for something much tighter than
truthiness. As you can see from my stats above, that's actually fairly
rare. Usually you'd just accept that True, 1, "yes", [1,2,3], and
1.2345 are all equally true.

ChrisA


From rosuav at gmail.com  Tue Mar  4 10:28:17 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 02:28:17 +1100
Subject: Functional programming
In-Reply-To: <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
 <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmovSNtrhTRm-FJYKbbWKCOmp8xksEVPsiD-gK-MChgnFw@mail.gmail.com>

On Wed, Mar 5, 2014 at 2:18 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> You don't need to have static typing to have declared variables. The two
> are independent. E.g. one might have a system like Python, except you
> have to declare your variables before using them:
>
> global x
> local a
> a = x+1

Aside: If you declare your locals, you shouldn't need to declare your
globals. Though I could imagine a rule that global rebinding still
needs to be declared, but you certainly shouldn't need to declare
nonlocal if you have a local declaration. Absence of local =>
nonlocal.

ChrisA


From __peter__ at web.de  Tue Mar  4 10:30:51 2014
From: __peter__ at web.de (Peter Otten)
Date: Tue, 04 Mar 2014 16:30:51 +0100
Subject: Logging
References: <CA+FnnTyg1-uP51KdhgSuriw4cb=KDtFQbt_bESiRM8Bnk8TtUA@mail.gmail.com>
Message-ID: <lf4riu$cos$1@ger.gmane.org>

Igor Korot wrote:

> Hi, ALL,
> Could someone please explain to me how the code in
> http://docs.python.org/2/howto/logging#logging-from-multiple-modules
> works?
> In particular I'm interested in how the mylib.py knows about the
> myapp.log.
> 
> What I mean is: logging object is not passed to mylib.py, so
> essentially it should create a new instance of the logging object.
> 
> What am I missing?

loggers are cached and organized in a tree. If you ask for a logger

abc = logging.getLogger("a.b.c")

you get the same logger every time. At the top of the tree there is the root 
logger

>>> import logging
>>> root = logging.getLogger()
>>> abc = logging.getLogger("a.b.c")
>>> ab = logging.getLogger("a.b")
>>> a = logging.getLogger("a")
>>> abc.parent is ab
True
>>> ab.parent is a
True
>>> a.parent is root
True
>>> logging.getLogger("a.b.c") is abc
True
>>> 


logging.info(...) 

is basically a shortcut for

root.info(...)

that also does a basicConfig() if necessary.

By default loggers delegate handling log messages to their parent. You only 
have to tell the root logger what to do with the incoming messages.

There are optimizations (placeholders for the intermediate loggers), but the 
above is the basic concept.

> But this question comes from the following fact about my application.
> I tried to create a logging object which will store the logging
> information to the file in the main class. Then I pass this object to
> another class constructor and use it in that second class.
> 
> Upon running everything is OK, but when the program successfully
> finishes, the log file has 0 length.
> 
> AFAIU, I'm doing it properly and the example referenced is wrong, yet
> the results are completely different.
> 
> Thank you for any expplanation.

Did you run the example consisting of myapp.py and myapp.lib? Did it work? 
If so, what did you differently in your real app?

Please provide a minimal example showing the unexpected behaviour.



From steve+comp.lang.python at pearwood.info  Tue Mar  4 10:42:03 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 15:42:03 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7720.1393946366.18130.python-list@python.org>
Message-ID: <5315f44a$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 10:19:22 -0500, Jerry Hill wrote:

> On Mon, Mar 3, 2014 at 11:52 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> If your intention is to treat None as a singleton sentinel, not as a
>> value, then you ought to use "is" to signal that intention, rather than
>> using == even if you know that there won't be any false positives.
> 
> In all of the years I've been on this list, I don't think I've seen more
> than one or two cases of someone deliberately treating None as a
> singleton sentinel.  In most cases, they're either checking the return
> value from a function 

Okay, that's not *precisely* a sentinel, but it's related. I don't know 
what to call that, but it's a sentinel applied to the return result 
rather than to an input parameter.


> or using it as a default argument to a function to
> force some default behavior when no parameter is passed.

I call that a sentinel. It doesn't match the Wikipedia definition of a 
sentinel, but I think that's wrong. What Wikipedia calls a sentinel, I 
would call a guard.

http://en.wikipedia.org/wiki/Sentinel_value



> I'm pretty
> sure you're going to say that the latter use is exactly where you should
> us 'is' instead of '=='.  

Yes.


> Respectfully, I disagree.
> 
> For a beginning python user, identity checking is an attractive
> nuisance. 

True. In Hypertalk, which was designed for non-coders, the "is" operator 
was a synonym for "==". Even after nearly 20 years of using Python, I 
still sometimes instinctively write "x is y" when I mean equality, 
especially the "if __name__ is __main__" idiom.


> The only time most beginners should use it is when comparing
> to None.

We're agreed on that.


> But, as soon as they are taught that there are two comparison
> operators, I start to see 'is' cropping up in more and more places where
> they ought to use '=='.  And the problem is that sometimes it works for
> them, and sometimes it doesn't.  Sure, students eventually need to
> understand the difference between identity and equality.  My problem is
> that by enshrining in python custom that the only correct way to compare
> to None is with 'is', we have to explain that concept way early in the
> teaching process.  I can't count the number of times that a thread has
> completely derailed into identity vs equality, then into interning of
> strings and small integers, and suddenly the thread is 40 messages long,
> and no one has actually talked about the code that was originally posted
> beyond that issue. 

Heh heh, welcome to the Internet.


> In approximately zero cases, have I seen code where
> 'is' versus '==' actually made any difference, except where the 'is' is
> wrong.  I've also never seen the supposedly ever-present boogie man of
> an object that mistakenly compares equal to None, much less seen that
> object passed to functions with None-based sentinels.
> 
> I feel like 'is' is an operator that ought to be saved for an advanced
> course.
> 
> Out of curiosity, do you think we should be doing truth checking with
> 'is'?  True and False are singletons, and it seems to me that the
> justification for idenity versus equality should be just as strong
> there, but I don't think I've ever seen anyone even suggest that.

Normally you shouldn't compare to True or False at all. Python duck-types 
truth-values, or to put it another way, you should normally only care 
about truthy and falsey values:

# Duck-typing is your friend
if flag: ...

# These are buggy unless you know flag is an actual bool
if flag == True: ...
if flag is True: ...

# Why convert to a canonical bool flag just to do a comparison?
if bool(flag): ...

# Not this
if bool(flag) is True:

# I never know when to stop
if bool(flag) is True is True is True is True is True is True: ...




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Tue Mar  4 10:45:51 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 04 Mar 2014 15:45:51 GMT
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
 <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7724.1393946907.18130.python-list@python.org>
Message-ID: <5315f52f$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Wed, 05 Mar 2014 02:28:17 +1100, Chris Angelico wrote:

> On Wed, Mar 5, 2014 at 2:18 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> You don't need to have static typing to have declared variables. The
>> two are independent. E.g. one might have a system like Python, except
>> you have to declare your variables before using them:
>>
>> global x
>> local a
>> a = x+1
> 
> Aside: If you declare your locals, you shouldn't need to declare your
> globals. Though I could imagine a rule that global rebinding still needs
> to be declared, but you certainly shouldn't need to declare nonlocal if
> you have a local declaration. Absence of local => nonlocal.

You missed that the purpose of the declaration is to avoid accidental 
typos:

local process
procces = 1234


With declarations, the compiler can catch some typos at compile-time.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Tue Mar  4 11:02:24 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 03:02:24 +1100
Subject: Reference
In-Reply-To: <5315f44a$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7720.1393946366.18130.python-list@python.org>
 <5315f44a$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmoN+qLp6GDpycQwymbjc5uykw71vieEKvXbwmBVdq7TwA@mail.gmail.com>

On Wed, Mar 5, 2014 at 2:42 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> # I never know when to stop
> if bool(flag) is True is True is True is True is True is True: ...

The banana problem.

ChrisA


From rosuav at gmail.com  Tue Mar  4 11:04:36 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 03:04:36 +1100
Subject: Functional programming
In-Reply-To: <5315f52f$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
 <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7724.1393946907.18130.python-list@python.org>
 <5315f52f$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmrezxL=2JP82d2fe0Cgms5ZLkqR4UkSYeNrqedQCQsU+A@mail.gmail.com>

On Wed, Mar 5, 2014 at 2:45 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
>> Aside: If you declare your locals, you shouldn't need to declare your
>> globals. Though I could imagine a rule that global rebinding still needs
>> to be declared, but you certainly shouldn't need to declare nonlocal if
>> you have a local declaration. Absence of local => nonlocal.
>
> You missed that the purpose of the declaration is to avoid accidental
> typos:
>
> local process
> procces = 1234
>
>
> With declarations, the compiler can catch some typos at compile-time.

Yep, but if you're declaring all your locals (and globals get declared
at module scope - they're just local to a different and broader
scope), then "procces" will never have been declared anywhere. You
shouldn't need to re-declare everything you're referencing from an
outer scope.

ChrisA


From __peter__ at web.de  Tue Mar  4 11:05:50 2014
From: __peter__ at web.de (Peter Otten)
Date: Tue, 04 Mar 2014 17:05:50 +0100
Subject: Decoding a process output
References: <lf46bg$5qc$1@ger.gmane.org>
Message-ID: <lf4tkk$76i$1@ger.gmane.org>

Francis Moreau wrote:

> Hi,
> 
> In my understanding (I'm relatively new to python), I need to decode any
> bytes data provided, in my case, by a shell command (such as findmnt)
> started by the subprocess module. The goal of my application is to parse
> the command outputs.
> 
> My application runs only on linux BTW and should run fine on both python
> 2.7 and py3k.
> 
> My question is when decoding the output bytes data of the external
> command, which encoding should I use ?
> 
> Should I guess the encoding by inspecting LANG or any LC_* environment
> variables ?
> 
> Should I force one of those environment variable to a specific value
> before running my external command ?
> 
> Thanks for any tips.

You can use locale.getpreferredencoding(), which seems to evaluate LANG:

$ python3 -c 'import locale; print(locale.getpreferredencoding())'
UTF-8
$ LANG= python3 -c 'import locale; print(locale.getpreferredencoding())'
ANSI_X3.4-1968

I haven't seen a Linux system that doesn't use UTF-8 for a while, but you 
have to remember that filenames are still arbitrary byte sequences. You can 
cope with this in Python by not decoding the bytes or using surrogateescape

>>> os.mkdir(bytes([i for i in range(1, 256) if i != b"/"[0]]))
>>> os.listdir(b".")
[b'\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f 
!"#$%&\'()*+,-.0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff']
>>> os.listdir(".")
['\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f 
!"#$%&\'()*+,-.0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7f\udc80\udc81\udc82\udc83\udc84\udc85\udc86\udc87\udc88\udc89\udc8a\udc8b\udc8c\udc8d\udc8e\udc8f\udc90\udc91\udc92\udc93\udc94\udc95\udc96\udc97\udc98\udc99\udc9a\udc9b\udc9c\udc9d\udc9e\udc9f\udca0\udca1\udca2\udca3\udca4\udca5\udca6\udca7\udca8\udca9\udcaa\udcab\udcac\udcad\udcae\udcaf\udcb0\udcb1\udcb2\udcb3\udcb4\udcb5\udcb6\udcb7\udcb8\udcb9\udcba\udcbb\udcbc\udcbd\udcbe\udcbf\udcc0\udcc1\udcc2\udcc3\udcc4\udcc5\udcc6\udcc7\udcc8\udcc9\udcca\udccb\udccc\udccd\udcce\udccf\udcd0\udcd1\udcd2\udcd3\udcd4\udcd5\udcd6\udcd7\udcd8\udcd9\udcda\udcdb\udcdc\udcdd\udcde\udcdf\udce0\udce1\udce2\udce3\udce4\udce5\udce6\udce7\udce8\udce9\udcea\udceb\udcec\udced\udcee\udcef\udcf0\udcf1\udcf2\udcf3\udcf4\udcf5\udcf6\udcf7\udcf8\udcf9\udcfa\udcfb\udcfc\udcfd\udcfe\udcff']

However, the typical shell tools have problems with names containing a 
newline or even space (and if not you may introduce such problems parsing 
the tool's output), so I'd like to see how findmnt responds to a mount point 
like the above directory.



From roy at panix.com  Tue Mar  4 11:14:13 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 04 Mar 2014 11:14:13 -0500
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7720.1393946366.18130.python-list@python.org>
 <5315f44a$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7726.1393948954.18130.python-list@python.org>
Message-ID: <roy-9649B8.11141304032014@news.panix.com>

In article <mailman.7726.1393948954.18130.python-list at python.org>,
 Chris Angelico <rosuav at gmail.com> wrote:

> On Wed, Mar 5, 2014 at 2:42 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
> > # I never know when to stop
> > if bool(flag) is True is True is True is True is True is True: ...
> 
> The banana problem.
> 
> ChrisA

You can refactor that as:

eval(" is ".join(itertools.chain(["if bool(flag)"], [str(t) for t in 
itertools.repeat(True)])))


From stefan_ml at behnel.de  Tue Mar  4 11:19:52 2014
From: stefan_ml at behnel.de (Stefan Behnel)
Date: Tue, 04 Mar 2014 17:19:52 +0100
Subject: how to get bytes from bytearray without copying
In-Reply-To: <lf4r5e$756$1@ger.gmane.org>
References: <lf0h3g$m7r$1@ger.gmane.org>
 <CALwzidncPvJS_aPJENre2HfOvV_PoY8mSV4PGA+i8FcwYPFc=A@mail.gmail.com>
 <lf4r5e$756$1@ger.gmane.org>
Message-ID: <lf4ueq$hoc$1@ger.gmane.org>

Juraj Ivan?i?, 04.03.2014 16:23:
> Just for reference, it is doable in pure Python, with ctypes help

For some questionable meaning of "pure".

Stefan




From rustompmody at gmail.com  Tue Mar  4 11:24:22 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 08:24:22 -0800 (PST)
Subject: Reference
In-Reply-To: <mailman.7720.1393946366.18130.python-list@python.org>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7720.1393946366.18130.python-list@python.org>
Message-ID: <cdf596e2-00c9-4598-bc8f-f8e14bd281d6@googlegroups.com>

On Tuesday, March 4, 2014 8:49:22 PM UTC+5:30, Jerry Hill wrote:
> On Mon, Mar 3, 2014 at 11:52 PM, Steven D'Aprano wrote:
> > If your intention is to treat None as a singleton sentinel, not as a
> > value, then you ought to use "is" to signal that intention, rather than
> > using == even if you know that there won't be any false positives.

> In all of the years I've been on this list, I don't think I've seen
> more than one or two cases of someone deliberately treating None as a
> singleton sentinel.  In most cases, they're either checking the return
> value from a function or using it as a default argument to a function
> to force some default behavior when no parameter is passed.  I'm
> pretty sure you're going to say that the latter use is exactly where
> you should us 'is' instead of '=='.  Respectfully, I disagree.

> For a beginning python user, identity checking is an attractive
> nuisance. The only time most beginners should use it is when comparing
> to None.  But, as soon as they are taught that there are two
> comparison operators, I start to see 'is' cropping up in more and more
> places where they ought to use '=='.  And the problem is that
> sometimes it works for them, and sometimes it doesn't.  Sure, students
> eventually need to understand the difference between identity and
> equality.  My problem is that by enshrining in python custom that the
> only correct way to compare to None is with 'is', we have to explain
> that concept way early in the teaching process.  I can't count the
> number of times that a thread has completely derailed into identity vs
> equality, then into interning of strings and small integers, and
> suddenly the thread is 40 messages long, and no one has actually
> talked about the code that was originally posted beyond that issue.
> In approximately zero cases, have I seen code where 'is' versus '=='
> actually made any difference, except where the 'is' is wrong.  I've
> also never seen the supposedly ever-present boogie man of an object
> that mistakenly compares equal to None, much less seen that object
> passed to functions with None-based sentinels.

Beautifully put -- thanks Jerry!

> I feel like 'is' is an operator that ought to be saved for an advanced course.

+100

My choice: have an isNone function which should take care of 90%
of the cases of valid 'is' (if I got Chris' statistics right) and avoid
most of the metaphysical BS about identity


From sffjunkie at gmail.com  Tue Mar  4 11:41:16 2014
From: sffjunkie at gmail.com (sffjunkie at gmail.com)
Date: Tue, 4 Mar 2014 08:41:16 -0800 (PST)
Subject: How security holes happen
In-Reply-To: <mailman.7678.1393887688.18130.python-list@python.org>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
Message-ID: <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>

On Monday, 3 March 2014 22:55:32 UTC, Chris Kaynor  wrote:
> You can go much simpler than that. Merely port Python to LISP, then write a LISP interpreter in Python. Done.

http://blog.pault.ag/post/46982895940/heres-my-talk-from-pycon-2013-i-tried-to-queue


From donarb at nwlink.com  Tue Mar  4 11:45:09 2014
From: donarb at nwlink.com (donarb)
Date: Tue, 4 Mar 2014 08:45:09 -0800 (PST)
Subject: modification time in Python - Django: datetime != datetime :-(
In-Reply-To: <mailman.7699.1393929204.18130.python-list@python.org>
References: <20140303133541.66fccbbb@lia.custard.shrl.nl>
 <CAPTjJmrp9Ca5zyfo75NKcX_ik0Qi4kOcjhhY6EEWKQ-xJx7KQg@mail.gmail.com>
 <mailman.7646.1393856904.18130.python-list@python.org>
 <04659633-e14e-4d5b-90f2-93af04f056be@googlegroups.com>
 <mailman.7699.1393929204.18130.python-list@python.org>
Message-ID: <d6b15bdd-895c-4efd-bd1c-f682de13b051@googlegroups.com>

Note that it's bad form to post the same question to different forums, you also posted this question to django-users. By posting to multiple forums, you run the risk of not having the question answered or followed up in one of the forums. This frustrates other users who may one day have a similar problem and find your orphaned question.

Remember, these forums are not just about you, they are also about those who follow later.


From python at mrabarnett.plus.com  Tue Mar  4 12:07:15 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 04 Mar 2014 17:07:15 +0000
Subject: Functional programming
In-Reply-To: <CAPTjJmqSfU_28jdonnDeqPZJO+zjpMWXGrBAJwvpKf0ZJVHyNg@mail.gmail.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
 <mailman.7713.1393941971.18130.python-list@python.org>
 <5315e963$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmqSfU_28jdonnDeqPZJO+zjpMWXGrBAJwvpKf0ZJVHyNg@mail.gmail.com>
Message-ID: <53160843.9090406@mrabarnett.plus.com>

On 2014-03-04 15:13, Chris Angelico wrote:
> On Wed, Mar 5, 2014 at 1:55 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> On Tue, 04 Mar 2014 14:05:44 +0000, Mark Lawrence wrote:
>>
>>> Once a statically typed language has been compiled the programmer can
>>> head down to the pub.
>>
>> "It compiles? Quick! Ship it!"
>>
>> Well, that certainly explains the quality of some programs...
>
> It explains the quality of other programs too. They were written after
> the programmer came back from the pub.
>
> *ducks for cover*
>
Or compiled before and tested after?



From rosuav at gmail.com  Tue Mar  4 12:07:44 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 04:07:44 +1100
Subject: How security holes happen
In-Reply-To: <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
Message-ID: <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>

On Wed, Mar 5, 2014 at 3:41 AM,  <sffjunkie at gmail.com> wrote:
> On Monday, 3 March 2014 22:55:32 UTC, Chris Kaynor  wrote:
>> You can go much simpler than that. Merely port Python to LISP, then write a LISP interpreter in Python. Done.
>
> http://blog.pault.ag/post/46982895940/heres-my-talk-from-pycon-2013-i-tried-to-queue

I don't have time to watch an hour-long video... what'd he do, exactly that?

ChrisA


From python at mrabarnett.plus.com  Tue Mar  4 12:10:10 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 04 Mar 2014 17:10:10 +0000
Subject: Origin of 'self'
In-Reply-To: <5315e2b9$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
 <7edah9989mdjb9mrnrsh5067np0ihv1jml@4ax.com>
 <mailman.7706.1393937237.18130.python-list@python.org>
 <5315e2b9$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <531608F2.4080302@mrabarnett.plus.com>

On 2014-03-04 14:27, Steven D'Aprano wrote:
> On Tue, 04 Mar 2014 12:47:09 +0000, MRAB wrote:
>
>> In AppleScript a script can refer to the title of a window as
>> "title of window" or "window's title", and it can refer to the
>> title of its own window as "title of window of me" or "me's
>> window's title". Consistent, yes, but bad English.
>>
>> That's why I prefer a programming language not to be too much like
>> a natural language. :-)
>
> But the problem with that is not that it is too much like a natural
> language, but too little like a natural language.
>
The more it's like a natural language, the more intelligent you expect
it to be, and the more you expect it to be able to work out ambiguities
for itself.


From python at mrabarnett.plus.com  Tue Mar  4 12:12:16 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 04 Mar 2014 17:12:16 +0000
Subject: Reference
In-Reply-To: <CAPTjJmoN+qLp6GDpycQwymbjc5uykw71vieEKvXbwmBVdq7TwA@mail.gmail.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7720.1393946366.18130.python-list@python.org>
 <5315f44a$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmoN+qLp6GDpycQwymbjc5uykw71vieEKvXbwmBVdq7TwA@mail.gmail.com>
Message-ID: <53160970.2090705@mrabarnett.plus.com>

On 2014-03-04 16:02, Chris Angelico wrote:
> On Wed, Mar 5, 2014 at 2:42 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> # I never know when to stop
>> if bool(flag) is True is True is True is True is True is True: ...
>
> The banana problem.
>
Speaking of which:

The 'right' way to peel a banana
http://www.telegraph.co.uk/news/good-to-share/10664935/The-right-way-to-peel-a-banana.html



From skip at pobox.com  Tue Mar  4 12:16:49 2014
From: skip at pobox.com (Skip Montanaro)
Date: Tue, 4 Mar 2014 11:16:49 -0600
Subject: How security holes happen
In-Reply-To: <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
Message-ID: <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>

On Tue, Mar 4, 2014 at 11:07 AM, Chris Angelico <rosuav at gmail.com> wrote:
> I don't have time to watch an hour-long video... what'd he do, exactly that?

If you fast forward to 16:14, his talk is about five minutes long. He
wrote a Lisp compiler whose backend is Python.

Skip


From roy at panix.com  Tue Mar  4 12:43:41 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 04 Mar 2014 12:43:41 -0500
Subject: modification time in Python - Django: datetime != datetime :-(
References: <20140303133541.66fccbbb@lia.custard.shrl.nl>
 <CAPTjJmrp9Ca5zyfo75NKcX_ik0Qi4kOcjhhY6EEWKQ-xJx7KQg@mail.gmail.com>
 <mailman.7646.1393856904.18130.python-list@python.org>
 <04659633-e14e-4d5b-90f2-93af04f056be@googlegroups.com>
 <mailman.7699.1393929204.18130.python-list@python.org>
 <d6b15bdd-895c-4efd-bd1c-f682de13b051@googlegroups.com>
Message-ID: <roy-8A538A.12434104032014@news.panix.com>

In article <d6b15bdd-895c-4efd-bd1c-f682de13b051 at googlegroups.com>,
 donarb <donarb at nwlink.com> wrote:

> Note that it's bad form to post the same question to different forums, you 
> also posted this question to django-users. By posting to multiple forums, you 
> run the risk of not having the question answered or followed up in one of the 
> forums. This frustrates other users who may one day have a similar problem 
> and find your orphaned question.

Even worse, you run the risk of having it answered differently in 
different places, and then you need to figure out which is right :-)


From marko at pacujo.net  Tue Mar  4 14:49:03 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 04 Mar 2014 21:49:03 +0200
Subject: Working with the set of real numbers
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
Message-ID: <87iortoic0.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> As far as I know, there's no simple way, in constant space and/or
> time, to progressively yield more digits of a number's square root,
> working in decimal.

I don't know why the constant space/time requirement is crucial. Anyway,
producing more digits simple: <URL: http://nrich.maths.org/5955>.

I believe producing the nth digit is O(n) in time and space.

Still, there's more to arithmetics than that. For example, if you have
two generated decimal expansions, you don't have an effective algorithm
to generate the decimal expansion of their ratio. That's because there's
no effective algorithm to decide if a < b.


Marko


From marko at pacujo.net  Tue Mar  4 14:49:13 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 04 Mar 2014 21:49:13 +0200
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
Message-ID: <87bnxloibq.fsf@elektro.pacujo.net>

Antoon Pardon <antoon.pardon at rece.vub.ac.be>:

> In the same way writing unit tests is the most tedious, boring,
> annoying, *unproductive* part. Amost always you are giving the program
> results it can work out for itself.

Undoubtedly, explicit type declarations add a dimension of quality to
software. However, they also significantly reduce readability and tempt
you to dirty shortcuts (to avoid writing truckloads of boilerplate
code).

On the balance, I estimate the explicit style reduces code quality.

Example (found by a random Google search):

===JAVA BEGIN===========================================================

class WrappedSqlException extends RuntimeException {
    static final long serialVersionUID = 20130808044800000L;
    public WrappedSqlException(SQLException cause) { super(cause); }
    public SQLException getSqlException() { return (SQLException) getCause(); }
}

public ConnectionPool(int maxConnections, String url) throws SQLException {
    try {
        super(() -> {
            try {
                return DriverManager.getConnection(url);
            } catch ( SQLException ex ) {
                throw new WrappedSqlException(ex);
            }
        }, maxConnections);
    } catch (WrappedSqlException wse) {
        throw wse.getSqlException();
    }
}

===JAVA END=============================================================

===PYTHON BEGIN=========================================================

def __init__(self, max_connections, url):
    super().__init__(lambda: DriverManager.get_connection(url), max_connections)

===PYTHON END===========================================================

or, a bit less cryptically:

===PYTHON BEGIN=========================================================

def __init__(self, max_connections, url):
    def get_connection():
        return DriverManager.get_connection(url)

    super().__init__(get_connection, max_connections)

===PYTHON END===========================================================


Marko


From rosuav at gmail.com  Tue Mar  4 14:58:23 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 06:58:23 +1100
Subject: Working with the set of real numbers
In-Reply-To: <87iortoic0.fsf@elektro.pacujo.net>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>

On Wed, Mar 5, 2014 at 6:49 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> As far as I know, there's no simple way, in constant space and/or
>> time, to progressively yield more digits of a number's square root,
>> working in decimal.
>
> I don't know why the constant space/time requirement is crucial. Anyway,
> producing more digits simple: <URL: http://nrich.maths.org/5955>.
>
> I believe producing the nth digit is O(n) in time and space.

The reason for striving for constant space/time is because the obvious
method (cut-and-try) is already O(n) for the nth digit, which means
it's quadratic on the number of digits desired. That gets pretty
nasty. So what I was asking was: By representing values as continued
fractions rather than as decimal digits, are you able to perform a
straight-forward transformation that produces the square root, in
constant time (which means linear in the length)? And I guess the
answer's no. CF representation doesn't have the advantage I was
wondering about.

ChrisA


From rosuav at gmail.com  Tue Mar  4 15:01:54 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 07:01:54 +1100
Subject: Functional programming
In-Reply-To: <87bnxloibq.fsf@elektro.pacujo.net>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <87bnxloibq.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpgOJ-gZCvhJzZXCLnXtKzkiWa_GLvp_3eHAtZyvevCbQ@mail.gmail.com>

On Wed, Mar 5, 2014 at 6:49 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> public ConnectionPool(int maxConnections, String url) throws SQLException {
>     try {
>         super(() -> {
>             try {
>                 return DriverManager.getConnection(url);
>             } catch ( SQLException ex ) {
>                 throw new WrappedSqlException(ex);
>             }
>         }, maxConnections);
>     } catch (WrappedSqlException wse) {
>         throw wse.getSqlException();
>     }
> }
>
> ===JAVA END=============================================================
>
> ===PYTHON BEGIN=========================================================
>
> def __init__(self, max_connections, url):
>     super().__init__(lambda: DriverManager.get_connection(url), max_connections)

You're not doing the same thing, though. The Java rigmarole is to
ensure that an SQLException thrown in getConnection will propagate up,
despite (presumably) something inside the equivalent of
super().__init__ that swallows SQLExceptions. Of course it looks
tidier when you don't do the messy bit.

ChrisA


From thrinassodon at thrinassodon.thrinassodon  Tue Mar  4 15:02:53 2014
From: thrinassodon at thrinassodon.thrinassodon (Thrinazodji0fecnfv)
Date: Tue, 04 Mar 2014 15:02:53 -0500
Subject: NEW RESEARCH TEARS  PALAEOANTHROPOLOGY APART: THE THRINAXODON TIMES
Message-ID: <lf5bh4$h4p$3@speranza.aioe.org>

===============
  >BREAKING NEWS!
===============
NEW YORK TIMES, THRINAXODON, OHIO
=====================
  >
THRINAXODON RECENTLY FOUND 3 HUMAN FOSSILS FROM DEVONIAN STRATA FROM
GREENLAND, THE EVOLUTIONISTS HAVE NO BONES ABOUT.
  >
ONE EVIL EVOLUTIONIST, BOB CASANOVA HAS ADMITTED THAT HUMAN EVOLUTION IS
IN FREE-FALL.
  >
RICHARD LEAKEY HAS DIED FROM A HEART ATTACK DUE TO THIS GROUND-BREAKING
FIND THAT CONCLUSIVELY SHOWS THAT HUMANS HAVE ORIGINS IN THE DEVONIAN.
  >
NOW, IF YOU PLEASE, I HAVE TO SUE THE SMITHSONIAN FOR YEARS OF CENSORSHIP.
  >
======================================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/6f501c469c7af24f#

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/3aad75c16afb0b82# 

-- 
---Thrinaxodon


From ned at nedbatchelder.com  Tue Mar  4 15:47:26 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Tue, 04 Mar 2014 15:47:26 -0500
Subject: How security holes happen
In-Reply-To: <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
Message-ID: <lf5e4d$lfm$1@ger.gmane.org>

On 3/4/14 12:16 PM, Skip Montanaro wrote:
> On Tue, Mar 4, 2014 at 11:07 AM, Chris Angelico <rosuav at gmail.com> wrote:
>> I don't have time to watch an hour-long video... what'd he do, exactly that?
>
> If you fast forward to 16:14, his talk is about five minutes long. He
> wrote a Lisp compiler whose backend is Python.
>
> Skip
>

It's Hy: http://hylang.org

-- 
Ned Batchelder, http://nedbatchelder.com



From marko at pacujo.net  Tue Mar  4 15:50:30 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 04 Mar 2014 22:50:30 +0200
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <87bnxloibq.fsf@elektro.pacujo.net>
 <mailman.7737.1393963318.18130.python-list@python.org>
Message-ID: <8738ixofhl.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Wed, Mar 5, 2014 at 6:49 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> public ConnectionPool(int maxConnections, String url) throws SQLException {
>>     try {
>>         super(() -> {
>>             try {
>>                 return DriverManager.getConnection(url);
>>             } catch ( SQLException ex ) {
>>                 throw new WrappedSqlException(ex);
>>             }
>>         }, maxConnections);
>>     } catch (WrappedSqlException wse) {
>>         throw wse.getSqlException();
>>     }
>> }
>>
>> ===JAVA END=============================================================
>
> You're not doing the same thing, though. The Java rigmarole is to
> ensure that an SQLException thrown in getConnection will propagate up,
> despite (presumably) something inside the equivalent of
> super().__init__ that swallows SQLExceptions. Of course it looks
> tidier when you don't do the messy bit.

See <URL: http://stackoverflow.com/questions/14039995/
java-8-mandatory-checked-exceptions-handling-in-lambd
a-expressions-for-standard>.

The "rigmarole" is trying to get around Java's mandatory exception
handling limitations, which Python doesn't have.

You are not allowed to pass a lambda to the super constructor that
throws an SQLException. To get around the limitation, a RuntimeException
wrapper is created to smuggle the SQLException through the compiler's
defenses. Any code is free to throw a RuntimeException.

I don't know, though, if this is that good of an example. I don't know
if the lambda gets called within the constructor or, as I would guess,
whenever a new connection is needed. The whole wrapping exercise would
be for nothing, then.

Here's a more prosaic example (probably contains errors):

===JAVA BEGIN===========================================================

private Map<TaxpayerIdNumber, Map<FormId, Form>> filings =
    new TreeMap<TaxpayerIdNumber, Map<FormId, Form>>();

class FormFiling {
    public FormFiling(TaxpayerIdNumber taxpayerId, Form form) {
        this.taxpayerId = taxpayerId;
        this.form = form;
    }

    public TaxpayerIdNumber getTaxpayerId() { return taxpayerId; }
    public Form getForm() { return form; }

    private TaxpayerIdNumber taxpayerId;
    private Form form;
};

List<FormFiling> getForms(FormId formId)
{
    List<FormFiling> forms = new LinkedList<FormFiling>();
    for (Map.Entry<TaxpayerIdNumber, Map<FormId, Form>> payerEntry :
         filings.entrySet()) {
        TaxpayerIdNumber taxpayerId = payerEntry.getKey();
        Map<FormId, Form> filing = payerEntry.getValue();
        if (filing.containsKey(formId))
            forms.add(new FormFiling(taxpayerId, filing.get(formId)))
    }
    return forms;
}

===JAVA END=============================================================

===PYTHON BEGIN=========================================================

filings = {}

def getForms(formId):
    forms = []
    for taxpayerId, filing in filings.iteritems():
         if formId in filing:
             forms.append((taxpayerId, filing[formId]))
    return forms

===PYTHON END===========================================================

or:

===PYTHON BEGIN=========================================================

filings = {}

def getForms(formId):
    return ((taxpayerId, filing[formId])
            for (taxpayerId, filing) in filings.iteritems()
            if formId in filing)

===PYTHON END===========================================================


Marko


From oscar.j.benjamin at gmail.com  Tue Mar  4 15:55:33 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Tue, 4 Mar 2014 20:55:33 +0000
Subject: Working with the set of real numbers
In-Reply-To: <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
Message-ID: <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>

On 4 March 2014 19:58, Chris Angelico <rosuav at gmail.com> wrote:
> On Wed, Mar 5, 2014 at 6:49 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> Chris Angelico <rosuav at gmail.com>:
>>
>>> As far as I know, there's no simple way, in constant space and/or
>>> time, to progressively yield more digits of a number's square root,
>>> working in decimal.
>>
>> I don't know why the constant space/time requirement is crucial. Anyway,
>> producing more digits simple: <URL: http://nrich.maths.org/5955>.
>>
>> I believe producing the nth digit is O(n) in time and space.
>
> The reason for striving for constant space/time is because the obvious
> method (cut-and-try) is already O(n) for the nth digit, which means
> it's quadratic on the number of digits desired. That gets pretty
> nasty.

I don't quite follow your reasoning here. By "cut-and-try" do you mean
bisection? If so it gives the first N decimal digits in N*log2(10)
iterations. However each iteration requires a multiply and when the
number of digits N becomes large the multiplication is worse than
linear. So the result is something like N**2 log(N)log(log(N)),

To me the obvious method is Newton iteration which takes O(sqrt(N))
iterations to obtain N digits of precision. This brings the above
complexity below quadratic:

#!/usr/bin/env python

from decimal import Decimal as D, localcontext

def sqrt(y, prec=1000):
    '''Solve x**2 = y'''
    assert y > 0
    eps = D(10) ** -(prec + 5)
    x = D(y)
    with localcontext() as ctx:
        ctx.prec = prec + 10
        while x ** 2 - y > x * eps:
            x = (x + y/x) / 2
    return x

print(sqrt(2))

Some modification would be required to handle a situation where it
ends in a run of nines or zeros if you really care about the exact
digits rather than having a bounded error.


Oscar


From ikorot01 at gmail.com  Tue Mar  4 15:57:08 2014
From: ikorot01 at gmail.com (Igor Korot)
Date: Tue, 4 Mar 2014 12:57:08 -0800
Subject: Proper conversion of timestamp
Message-ID: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>

Hi, ALL,
I'm getting this:

timestamp out of range for platform localtime()/gmtime() function

trying to convert the timestamp with milliseconds into the datetime object.

The first hit of Google gives me this:

http://stackoverflow.com/questions/12458595/convert-epoch-timestamp-in-python

but the solution described is not good for me since it does not gives
me the milliseconds value.

How do I get the proper datetime value including milliseconds from the
timestamp?

Thank you.


From rosuav at gmail.com  Tue Mar  4 16:06:17 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 08:06:17 +1100
Subject: Functional programming
In-Reply-To: <8738ixofhl.fsf@elektro.pacujo.net>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <87bnxloibq.fsf@elektro.pacujo.net>
 <mailman.7737.1393963318.18130.python-list@python.org>
 <8738ixofhl.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpYbgS6ajiXdC7+as-puociY4dKoh1gPUv+RNDxMWivvw@mail.gmail.com>

On Wed, Mar 5, 2014 at 7:50 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> The "rigmarole" is trying to get around Java's mandatory exception
> handling limitations, which Python doesn't have.
>
> You are not allowed to pass a lambda to the super constructor that
> throws an SQLException. To get around the limitation, a RuntimeException
> wrapper is created to smuggle the SQLException through the compiler's
> defenses. Any code is free to throw a RuntimeException.
>

Oh, it's THAT problem. Well, it's still not really a fair comparison
of declared types. It shows how Python's much easier to work with, but
what you're showing off is the simpler exception handling :)

ChrisA


From marko at pacujo.net  Tue Mar  4 16:05:06 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 04 Mar 2014 23:05:06 +0200
Subject: Working with the set of real numbers
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <mailman.7739.1393966562.18130.python-list@python.org>
Message-ID: <87y50pn08t.fsf@elektro.pacujo.net>

Oscar Benjamin <oscar.j.benjamin at gmail.com>:

> To me the obvious method is Newton iteration which takes O(sqrt(N))
> iterations to obtain N digits of precision. This brings the above
> complexity below quadratic:
>
> #!/usr/bin/env python
>
> from decimal import Decimal as D, localcontext
>
> def sqrt(y, prec=1000):
>     '''Solve x**2 = y'''
>     assert y > 0
>     eps = D(10) ** -(prec + 5)
>     x = D(y)
>     with localcontext() as ctx:
>         ctx.prec = prec + 10
>         while x ** 2 - y > x * eps:
>             x = (x + y/x) / 2
>     return x
>
> print(sqrt(2))

At a quick glance, I believe x ** 2 is O(N?) and so the total complexity
should be O(N ** 2.5).


Marko


From rosuav at gmail.com  Tue Mar  4 16:18:29 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 08:18:29 +1100
Subject: Working with the set of real numbers
In-Reply-To: <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
Message-ID: <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>

On Wed, Mar 5, 2014 at 7:55 AM, Oscar Benjamin
<oscar.j.benjamin at gmail.com> wrote:
> I don't quite follow your reasoning here. By "cut-and-try" do you mean
> bisection? If so it gives the first N decimal digits in N*log2(10)
> iterations. However each iteration requires a multiply and when the
> number of digits N becomes large the multiplication is worse than
> linear. So the result is something like N**2 log(N)log(log(N)),

By "cut and try" I'm talking about the really REALLY simple algorithm
for calculating square roots. It's basically brute force.

epsilon = 0.0001
def sqrt(n):
    guess1, guess2 = 1, n
    while abs(guess1-guess2) > epsilon:
        guess1 = n/guess2
        guess2 = (guess1 + guess2)/2
   return guess1

It's generally going to take roughly O(n*n) time to generate n digits,
give or take. That's the baseline against which anything else can be
compared. There are plenty of better ways to calculate them.

ChrisA


From marko at pacujo.net  Tue Mar  4 16:21:44 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 04 Mar 2014 23:21:44 +0200
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <87bnxloibq.fsf@elektro.pacujo.net>
 <mailman.7737.1393963318.18130.python-list@python.org>
 <8738ixofhl.fsf@elektro.pacujo.net>
 <mailman.7741.1393967180.18130.python-list@python.org>
Message-ID: <87txbdmzh3.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Oh, it's THAT problem. Well, it's still not really a fair comparison
> of declared types. It shows how Python's much easier to work with, but
> what you're showing off is the simpler exception handling :)

The other example I gave is really bread-and-butter Java. An ergonomic
disaster and takes some staring at to figure out what's going on.

Note that Java doesn't possess typedef's so you really are pretty much
forced to write those < , < >>'s a lot.


Marko


From rosuav at gmail.com  Tue Mar  4 16:26:53 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 08:26:53 +1100
Subject: Functional programming
In-Reply-To: <87txbdmzh3.fsf@elektro.pacujo.net>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <87bnxloibq.fsf@elektro.pacujo.net>
 <mailman.7737.1393963318.18130.python-list@python.org>
 <8738ixofhl.fsf@elektro.pacujo.net>
 <mailman.7741.1393967180.18130.python-list@python.org>
 <87txbdmzh3.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmorUSxtjsgojh1OmAu_MvCieTuXyp0koDje=ea078pRnQ@mail.gmail.com>

On Wed, Mar 5, 2014 at 8:21 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> Oh, it's THAT problem. Well, it's still not really a fair comparison
>> of declared types. It shows how Python's much easier to work with, but
>> what you're showing off is the simpler exception handling :)
>
> The other example I gave is really bread-and-butter Java. An ergonomic
> disaster and takes some staring at to figure out what's going on.
>
> Note that Java doesn't possess typedef's so you really are pretty much
> forced to write those < , < >>'s a lot.

C++ at least has typedefs, and in the newer standards, the 'auto'
keyword was repurposed.

ChrisA


From python at mrabarnett.plus.com  Tue Mar  4 16:38:06 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 04 Mar 2014 21:38:06 +0000
Subject: Proper conversion of timestamp
In-Reply-To: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
Message-ID: <531647BE.70104@mrabarnett.plus.com>

On 2014-03-04 20:57, Igor Korot wrote:
> Hi, ALL,
> I'm getting this:
>
> timestamp out of range for platform localtime()/gmtime() function
>
> trying to convert the timestamp with milliseconds into the datetime object.
>
> The first hit of Google gives me this:
>
> http://stackoverflow.com/questions/12458595/convert-epoch-timestamp-in-python
>
> but the solution described is not good for me since it does not gives
> me the milliseconds value.
>
> How do I get the proper datetime value including milliseconds from the
> timestamp?
>
> Thank you.
>
Are you using Python 2? If yes, then try dividing by 1000.0.



From stefan at bytereef.org  Tue Mar  4 16:35:48 2014
From: stefan at bytereef.org (Stefan Krah)
Date: Tue, 4 Mar 2014 21:35:48 +0000 (UTC)
Subject: python decimal library dmath.py v0.3 released
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>
 <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>
 <27d19767-84ee-4ab7-87fd-784e8ac57680@googlegroups.com>
Message-ID: <loom.20140304T222838-808@post.gmane.org>


[I found this via the python-ideas thread]

Wolfgang Maier <wolfgang.maier <at> biologie.uni-freiburg.de> writes:
> math.factorial is accurate and faster than your pure-Python function,
especially for large numbers.

It is slower for huge numbers than decimal if you use this
Python function:

http://www.bytereef.org/mpdecimal/quickstart.html#factorial-in-pure-python


Be sure to set MAX_EMAX and MIN_EMIN, that's missing in the example.


If you want to *see* all digits of a very large number, then decimal is
probably even faster than gmpy. See:

http://www.bytereef.org/mpdecimal/benchmarks.html#arbitrary-precision-libraries



Stefan Krah



From breamoreboy at yahoo.co.uk  Tue Mar  4 16:44:04 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 04 Mar 2014 21:44:04 +0000
Subject: Proper conversion of timestamp
In-Reply-To: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
Message-ID: <lf5hes$ve3$1@ger.gmane.org>

On 04/03/2014 20:57, Igor Korot wrote:
> Hi, ALL,
> I'm getting this:
>
> timestamp out of range for platform localtime()/gmtime() function
>
> trying to convert the timestamp with milliseconds into the datetime object.
>
> The first hit of Google gives me this:
>
> http://stackoverflow.com/questions/12458595/convert-epoch-timestamp-in-python
>
> but the solution described is not good for me since it does not gives
> me the milliseconds value.
>
> How do I get the proper datetime value including milliseconds from the
> timestamp?
>
> Thank you.
>

You have a long record of asking timestamp related questions so you 
should know where the docs are that provide the answer to this question. 
  I'll leave you to go off and read them.  If you don't understand them, 
please cut and paste your code here, state what you expected to happen, 
what actually happened, including any traceback if applicable, and then 
we'll be happy to point you the error of your ways.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From marko at pacujo.net  Tue Mar  4 16:43:05 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 04 Mar 2014 23:43:05 +0200
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <87bnxloibq.fsf@elektro.pacujo.net>
 <mailman.7737.1393963318.18130.python-list@python.org>
 <8738ixofhl.fsf@elektro.pacujo.net>
 <mailman.7741.1393967180.18130.python-list@python.org>
 <87txbdmzh3.fsf@elektro.pacujo.net>
 <mailman.7743.1393968417.18130.python-list@python.org>
Message-ID: <87ppm1myhi.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> C++ at least has typedefs, and in the newer standards, the 'auto'
> keyword was repurposed.

Last I checked, C++ had no satisfactory way to express
callbacks/functors/listeners/lambdas. That's why Qt came up with a
metacompiler to supplement C++'s facilities.

No, STL and Boost can't remedy the situation.

The main reason was the unfortunate way method pointers were defined in
C++. C#'s delegates and Java's anonymous inner classes are something a
C++ developer can only dream of (unless something has already been
dreamt up in a recent standard).

Python, of course, has delegates:

   that_object.register_callback(self.handle_it)

Python doesn't have anonymous inner classes, but it has named inner
classes, and that's quite sufficient.


Marko


From ikorot01 at gmail.com  Tue Mar  4 16:46:21 2014
From: ikorot01 at gmail.com (Igor Korot)
Date: Tue, 4 Mar 2014 13:46:21 -0800
Subject: Proper conversion of timestamp
In-Reply-To: <531647BE.70104@mrabarnett.plus.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <531647BE.70104@mrabarnett.plus.com>
Message-ID: <CA+FnnTwWXnZ_PtNuwa-8dp5VEMzxMj6CKXiFbzBuEUBzHLKdkQ@mail.gmail.com>

MRAB,


On Tue, Mar 4, 2014 at 1:38 PM, MRAB <python at mrabarnett.plus.com> wrote:

> On 2014-03-04 20:57, Igor Korot wrote:
>
>> Hi, ALL,
>> I'm getting this:
>>
>> timestamp out of range for platform localtime()/gmtime() function
>>
>> trying to convert the timestamp with milliseconds into the datetime
>> object.
>>
>> The first hit of Google gives me this:
>>
>> http://stackoverflow.com/questions/12458595/convert-
>> epoch-timestamp-in-python
>>
>> but the solution described is not good for me since it does not gives
>> me the milliseconds value.
>>
>> How do I get the proper datetime value including milliseconds from the
>> timestamp?
>>
>> Thank you.
>>
>>  Are you using Python 2? If yes, then try dividing by 1000.0.
>

Yes, I'm using python 2.7.
But dividing by 1000 will give the precision in seconds, i.e. "YYYY-MM-DD
HH:MM:SS".

What I want is to have this: "YYYY-MM-DD HH:MM:SS.XXX", where "XXX" is a
milliseconds.

Thank you.


>
> --
> https://mail.python.org/mailman/listinfo/python-list
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From breamoreboy at yahoo.co.uk  Tue Mar  4 16:45:50 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 04 Mar 2014 21:45:50 +0000
Subject: Proper conversion of timestamp
In-Reply-To: <531647BE.70104@mrabarnett.plus.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <531647BE.70104@mrabarnett.plus.com>
Message-ID: <lf5hi6$ve3$2@ger.gmane.org>

On 04/03/2014 21:38, MRAB wrote:
> On 2014-03-04 20:57, Igor Korot wrote:
>> Hi, ALL,
>> I'm getting this:
>>
>> timestamp out of range for platform localtime()/gmtime() function
>>
>> trying to convert the timestamp with milliseconds into the datetime
>> object.
>>
>> The first hit of Google gives me this:
>>
>> http://stackoverflow.com/questions/12458595/convert-epoch-timestamp-in-python
>>
>>
>> but the solution described is not good for me since it does not gives
>> me the milliseconds value.
>>
>> How do I get the proper datetime value including milliseconds from the
>> timestamp?
>>
>> Thank you.
>>
> Are you using Python 2? If yes, then try dividing by 1000.0.
>

You learn something new every day, I wasn't aware that you could 
multiply or divide timestamps.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Tue Mar  4 16:52:57 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 08:52:57 +1100
Subject: Functional programming
In-Reply-To: <87ppm1myhi.fsf@elektro.pacujo.net>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
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 <mailman.7700.1393930643.18130.python-list@python.org>
 <87bnxloibq.fsf@elektro.pacujo.net>
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 <8738ixofhl.fsf@elektro.pacujo.net>
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 <87txbdmzh3.fsf@elektro.pacujo.net>
 <mailman.7743.1393968417.18130.python-list@python.org>
 <87ppm1myhi.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpsjfy9ENcHC6qEZRMFREuw7M6rJu_8EQbeBG66P2M0TA@mail.gmail.com>

On Wed, Mar 5, 2014 at 8:43 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> C++ at least has typedefs, and in the newer standards, the 'auto'
>> keyword was repurposed.
>
> Last I checked, C++ had no satisfactory way to express
> callbacks/functors/listeners/lambdas. That's why Qt came up with a
> metacompiler to supplement C++'s facilities.

I think one of the recent standards added some kind of closure for
callbacks. I tried to grok it and couldn't figure out what it was
doing, so I gave it up as a bad job. It got hairy. Really hairy.
Either that, or I was reading a poorly-written article, which is also
possible.

ChrisA


From news at blinne.net  Tue Mar  4 16:53:22 2014
From: news at blinne.net (Alexander Blinne)
Date: Tue, 04 Mar 2014 22:53:22 +0100
Subject: Reference
In-Reply-To: <mailman.7714.1393941984.18130.python-list@python.org>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <mailman.7654.1393872546.18130.python-list@python.org>
 <5315cd4b$0$6670$9b4e6d93@newsspool2.arcor-online.net>
 <mailman.7714.1393941984.18130.python-list@python.org>
Message-ID: <53164b54$0$6663$9b4e6d93@newsspool2.arcor-online.net>

Am 04.03.2014 15:06, schrieb Chris Angelico:
> https://github.com/Rosuav/ExceptExpr/blob/master/find_except_expr.py

I have always found it quite nice that the python parser is so easy to
use from within python itself.

> Run across the Python stdlib, that tells me there are 4040 uses of
> is/is not, of which 16 compare against False, 18 against True (see?
> Python has a bias for truth above falsehood!), and 3386 against None.

I think i will have to rephrase my "is False" condition to make it more
truthy :)


From ikorot01 at gmail.com  Tue Mar  4 16:55:11 2014
From: ikorot01 at gmail.com (Igor Korot)
Date: Tue, 4 Mar 2014 13:55:11 -0800
Subject: Proper conversion of timestamp
In-Reply-To: <lf5hes$ve3$1@ger.gmane.org>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
Message-ID: <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>

Hi, Mark,


On Tue, Mar 4, 2014 at 1:44 PM, Mark Lawrence <breamoreboy at yahoo.co.uk>wrote:

> On 04/03/2014 20:57, Igor Korot wrote:
>
>> Hi, ALL,
>> I'm getting this:
>>
>> timestamp out of range for platform localtime()/gmtime() function
>>
>> trying to convert the timestamp with milliseconds into the datetime
>> object.
>>
>> The first hit of Google gives me this:
>>
>> http://stackoverflow.com/questions/12458595/convert-
>> epoch-timestamp-in-python
>>
>> but the solution described is not good for me since it does not gives
>> me the milliseconds value.
>>
>> How do I get the proper datetime value including milliseconds from the
>> timestamp?
>>
>> Thank you.
>>
>>
> You have a long record of asking timestamp related questions so you should
> know where the docs are that provide the answer to this question.  I'll
> leave you to go off and read them.  If you don't understand them, please
> cut and paste your code here, state what you expected to happen, what
> actually happened, including any traceback if applicable, and then we'll be
> happy to point you the error of your ways.
>

Working with the dates is not that easy and not just in Python.
There are too many different formatting involved with many different
representation.
And on top of it it is possible to use one system in completely different
environment.

But this particular question is easy.

What I have is a timestamp which reads: 1289410678L.

Trying to convert this into the datetime object in Python using:

import datetime
datetime.datetime.fromtimestamp( stamp )

produces the error: timestamp out of range for platform
localtime()/gmtime() function.

This is because this timestamp is not in seconds, but rather in
milliseconds.

Now the question I have is: how do I properly convert this timestamp into
the datetime object with the milliseconds?

Thank you.


>
> --
> My fellow Pythonistas, ask not what our language can do for you, ask what
> you can do for our language.
>
> Mark Lawrence
>
> ---
> This email is free from viruses and malware because avast! Antivirus
> protection is active.
> http://www.avast.com
>
>
> --
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>
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From rosuav at gmail.com  Tue Mar  4 16:55:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 08:55:43 +1100
Subject: Proper conversion of timestamp
In-Reply-To: <CA+FnnTwWXnZ_PtNuwa-8dp5VEMzxMj6CKXiFbzBuEUBzHLKdkQ@mail.gmail.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <531647BE.70104@mrabarnett.plus.com>
 <CA+FnnTwWXnZ_PtNuwa-8dp5VEMzxMj6CKXiFbzBuEUBzHLKdkQ@mail.gmail.com>
Message-ID: <CAPTjJmoq2Vqbc2wajS+-ik4SnJWvX6pz1BKBcE+5y2QZZLt=Lw@mail.gmail.com>

On Wed, Mar 5, 2014 at 8:46 AM, Igor Korot <ikorot01 at gmail.com> wrote:
>> Are you using Python 2? If yes, then try dividing by 1000.0.
>
>
> Yes, I'm using python 2.7.
> But dividing by 1000 will give the precision in seconds, i.e. "YYYY-MM-DD
> HH:MM:SS".

Did you notice the bit at the end there? Try dividing by 1000.0, see
if that's any different.

ChrisA


From ikorot01 at gmail.com  Tue Mar  4 16:57:56 2014
From: ikorot01 at gmail.com (Igor Korot)
Date: Tue, 4 Mar 2014 13:57:56 -0800
Subject: Proper conversion of timestamp
In-Reply-To: <lf5hi6$ve3$2@ger.gmane.org>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <531647BE.70104@mrabarnett.plus.com> <lf5hi6$ve3$2@ger.gmane.org>
Message-ID: <CA+FnnTwu9C2r8ZSQbyw6Ao7vcSuc_A1V8aAMD5sywtjsQNqTrQ@mail.gmail.com>

Mark,


On Tue, Mar 4, 2014 at 1:45 PM, Mark Lawrence <breamoreboy at yahoo.co.uk>wrote:

> On 04/03/2014 21:38, MRAB wrote:
>
>> On 2014-03-04 20:57, Igor Korot wrote:
>>
>>> Hi, ALL,
>>> I'm getting this:
>>>
>>> timestamp out of range for platform localtime()/gmtime() function
>>>
>>> trying to convert the timestamp with milliseconds into the datetime
>>> object.
>>>
>>> The first hit of Google gives me this:
>>>
>>> http://stackoverflow.com/questions/12458595/convert-
>>> epoch-timestamp-in-python
>>>
>>>
>>> but the solution described is not good for me since it does not gives
>>> me the milliseconds value.
>>>
>>> How do I get the proper datetime value including milliseconds from the
>>> timestamp?
>>>
>>> Thank you.
>>>
>>>  Are you using Python 2? If yes, then try dividing by 1000.0.
>>
>>
> You learn something new every day, I wasn't aware that you could multiply
> or divide timestamps.


Of course you can. Its just the number.
And this is exactly what happens on the stackoverflow question I referenced
in the OP.
Problem is I want the milliseconds in the datetime object.

Thank you.


>
>
> --
> My fellow Pythonistas, ask not what our language can do for you, ask what
> you can do for our language.
>
> Mark Lawrence
>
> ---
> This email is free from viruses and malware because avast! Antivirus
> protection is active.
> http://www.avast.com
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>
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From rosuav at gmail.com  Tue Mar  4 17:01:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 09:01:43 +1100
Subject: Reference
In-Reply-To: <53164b54$0$6663$9b4e6d93@newsspool2.arcor-online.net>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <mailman.7654.1393872546.18130.python-list@python.org>
 <5315cd4b$0$6670$9b4e6d93@newsspool2.arcor-online.net>
 <mailman.7714.1393941984.18130.python-list@python.org>
 <53164b54$0$6663$9b4e6d93@newsspool2.arcor-online.net>
Message-ID: <CAPTjJmq2=ua9hk_R5PO0EY2L4ezanmJ5A5kATKTg4VZh6sZTzg@mail.gmail.com>

On Wed, Mar 5, 2014 at 8:53 AM, Alexander Blinne <news at blinne.net> wrote:
> Am 04.03.2014 15:06, schrieb Chris Angelico:
>> https://github.com/Rosuav/ExceptExpr/blob/master/find_except_expr.py
>
> I have always found it quite nice that the python parser is so easy to
> use from within python itself.

Yes. Until I put together the original version of that, to search for
PEP 463 translation candidates, I'd never used the ast module other
than for literal_eval. It's marvelously powerful.

>> Run across the Python stdlib, that tells me there are 4040 uses of
>> is/is not, of which 16 compare against False, 18 against True (see?
>> Python has a bias for truth above falsehood!), and 3386 against None.
>
> I think i will have to rephrase my "is False" condition to make it more
> truthy :)

if x is False:

-->

if not x:

ChrisA


From oscar.j.benjamin at gmail.com  Tue Mar  4 17:02:15 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Tue, 4 Mar 2014 22:02:15 +0000
Subject: Working with the set of real numbers
In-Reply-To: <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
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Message-ID: <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>

On 4 March 2014 21:18, Chris Angelico <rosuav at gmail.com> wrote:
> On Wed, Mar 5, 2014 at 7:55 AM, Oscar Benjamin
> <oscar.j.benjamin at gmail.com> wrote:
>> I don't quite follow your reasoning here. By "cut-and-try" do you mean
>> bisection? If so it gives the first N decimal digits in N*log2(10)
>> iterations. However each iteration requires a multiply and when the
>> number of digits N becomes large the multiplication is worse than
>> linear. So the result is something like N**2 log(N)log(log(N)),
>
> By "cut and try" I'm talking about the really REALLY simple algorithm
> for calculating square roots. It's basically brute force.
>
> epsilon = 0.0001
> def sqrt(n):
>     guess1, guess2 = 1, n
>     while abs(guess1-guess2) > epsilon:
>         guess1 = n/guess2
>         guess2 = (guess1 + guess2)/2
>    return guess1

That's the exact same algorithm I showed! How on earth would you call
that brute force?

> It's generally going to take roughly O(n*n) time to generate n digits,
> give or take.

It does not take O(n*n) time. This is Newton iteration and for
well-behaved problems such as this it generates more than n digits
after n iterations. I modified my code to show the error (x**2 - y) at
each iteration:

$ python3.3 root.py
2
0.2
0.007
0.000006
5E-12
3E-24
8E-49
8E-98
8E-196
9E-392
1E-783

The number of correct digits doubles at each iteration so after n
iterations you have 2**n digits (I misstated this as n**2 before).
This means that it takes log(N) iterations to get N digits. See here
for more:
http://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method

See also the section below that:
http://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Digit-by-digit_calculation

> That's the baseline against which anything else can be
> compared. There are plenty of better ways to calculate them.

Such as?


Oscar


From rosuav at gmail.com  Tue Mar  4 17:03:05 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 09:03:05 +1100
Subject: Proper conversion of timestamp
In-Reply-To: <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
 <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
Message-ID: <CAPTjJmoHOH9tYBuOpiT3vYU5gYBNiaHNPM4t1Zt8nxJSthS0WA@mail.gmail.com>

On Wed, Mar 5, 2014 at 8:55 AM, Igor Korot <ikorot01 at gmail.com> wrote:
>
> This is because this timestamp is not in seconds, but rather in
> milliseconds.
>
> Now the question I have is: how do I properly convert this timestamp into
> the datetime object with the milliseconds?

Read elsewhere in the thread, two people have explained this already.

ChrisA


From oscar.j.benjamin at gmail.com  Tue Mar  4 17:08:44 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Tue, 4 Mar 2014 22:08:44 +0000
Subject: Working with the set of real numbers
In-Reply-To: <87y50pn08t.fsf@elektro.pacujo.net>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <mailman.7739.1393966562.18130.python-list@python.org>
 <87y50pn08t.fsf@elektro.pacujo.net>
Message-ID: <CAHVvXxSxGOEzXntUZB2tOcEJe63bNrWc6JA+27M03Hi=DzvSVA@mail.gmail.com>

On 4 March 2014 21:05, Marko Rauhamaa <marko at pacujo.net> wrote:
> Oscar Benjamin <oscar.j.benjamin at gmail.com>:
>
>> To me the obvious method is Newton iteration which takes O(sqrt(N))
>> iterations to obtain N digits of precision. This brings the above
>> complexity below quadratic:
>>
>> #!/usr/bin/env python
>>
>> from decimal import Decimal as D, localcontext
>>
>> def sqrt(y, prec=1000):
>>     '''Solve x**2 = y'''
>>     assert y > 0
>>     eps = D(10) ** -(prec + 5)
>>     x = D(y)
>>     with localcontext() as ctx:
>>         ctx.prec = prec + 10
>>         while x ** 2 - y > x * eps:
>>             x = (x + y/x) / 2
>>     return x
>>
>> print(sqrt(2))
>
> At a quick glance, I believe x ** 2 is O(N?) and so the total complexity
> should be O(N ** 2.5).

x**2 is just a multiplication which can be done in better than O(N**2):
http://en.wikipedia.org/wiki/Multiplication_algorithm#Fast_multiplication_algorithms_for_large_inputs


Oscar


From rosuav at gmail.com  Tue Mar  4 17:18:33 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 09:18:33 +1100
Subject: Working with the set of real numbers
In-Reply-To: <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
 <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>
 <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>
Message-ID: <CAPTjJmpcM9vLG8pKqDtOBgMDpbo3S2N+7Dv7BAPKbhNTjOTA4g@mail.gmail.com>

On Wed, Mar 5, 2014 at 9:02 AM, Oscar Benjamin
<oscar.j.benjamin at gmail.com> wrote:
> On 4 March 2014 21:18, Chris Angelico <rosuav at gmail.com> wrote:
>> On Wed, Mar 5, 2014 at 7:55 AM, Oscar Benjamin
>> <oscar.j.benjamin at gmail.com> wrote:
>>> I don't quite follow your reasoning here. By "cut-and-try" do you mean
>>> bisection? If so it gives the first N decimal digits in N*log2(10)
>>> iterations. However each iteration requires a multiply and when the
>>> number of digits N becomes large the multiplication is worse than
>>> linear. So the result is something like N**2 log(N)log(log(N)),
>>
>> By "cut and try" I'm talking about the really REALLY simple algorithm
>> for calculating square roots. It's basically brute force.
>>
>> epsilon = 0.0001
>> def sqrt(n):
>>     guess1, guess2 = 1, n
>>     while abs(guess1-guess2) > epsilon:
>>         guess1 = n/guess2
>>         guess2 = (guess1 + guess2)/2
>>    return guess1
>
> That's the exact same algorithm I showed! How on earth would you call
> that brute force?

It uses a lot of division. There are various refinements that can be
done that replace some of that division with multiplication, but I'd
have to go do some research to figure it out.

This is the purest form of attempted-division algorithm. If you're
describing it on a blackboard, you would write it pretty much like
this. At each iteration, you have to divide by a number that's n
digits long, and then do some additional arithmetic.

>> It's generally going to take roughly O(n*n) time to generate n digits,
>> give or take.
>
> It does not take O(n*n) time. This is Newton iteration and for
> well-behaved problems such as this it generates more than n digits
> after n iterations. I modified my code to show the error (x**2 - y) at
> each iteration:
>
> $ python3.3 root.py
> 2
> 0.2
> 0.007
> 0.000006
> 5E-12
> 3E-24
> 8E-49
> 8E-98
> 8E-196
> 9E-392
> 1E-783
>
> The number of correct digits doubles at each iteration so after n
> iterations you have 2**n digits (I misstated this as n**2 before).
> This means that it takes log(N) iterations to get N digits.

It seems I'm partly mistaken, though not entirely. Let's compare two
versions. In the first, you set the precision (I'm talking in terms of
REXX's "NUMERIC DIGITS" statement - anything beyond this many digits
will be rounded (and represented exponentially, if necessary); I'm not
sure if decimal.Decimal precision works this way) such that you get 10
digits. Each iteration requires division by a 10-digit number, which
is an operation that takes a certain amount of time; and it's going to
take some number of iterations to get to the final answer.

Second version, you set the precision so you get 20 digits. Now, it's
going to take you approximately one more iteration to get to the final
answer. (This bit I was mistaken on. I thought it would take something
like 25% more or 50% more iterations.) But each iteration will take
longer. The complexity of division depends on the algorithm - grade
school long division would be O(n) with a fixed-length dividend, I
think, but you could probably pull that down a bit.

So that's why I said it'd be very roughly O(n*n) - because the
division in each step is O(n), and I thought it'd take O(n) steps.
Turns out it's O(n*log(n)), which is a lot better.

>> That's the baseline against which anything else can be
>> compared. There are plenty of better ways to calculate them.
>
> Such as?

Improved versions of the above, and I was under the impression that
there were some completely different techniques that converged a lot
more quickly. But it may be that I was mistaken, as I'd been expecting
this to converge in O(n) steps. Reducing the amount of division would
speed things up significantly, although it probably won't change the
algorithmic complexity.

So, put it down to misremembering and thinking the simple algorithm
was worse than it actually is :)

ChrisA


From ethan at stoneleaf.us  Tue Mar  4 17:05:35 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Tue, 04 Mar 2014 14:05:35 -0800
Subject: Proper conversion of timestamp
In-Reply-To: <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
 <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
Message-ID: <53164E2F.4020807@stoneleaf.us>

On 03/04/2014 01:55 PM, Igor Korot wrote:
>
> Now the question I have is: how do I properly convert this timestamp
> into the datetime object with the milliseconds?

And Mark's point is:  How do the docs say to do it?  What fails when you 
try it that way?

--
~Ethan~



From ethan at stoneleaf.us  Tue Mar  4 16:49:38 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Tue, 04 Mar 2014 13:49:38 -0800
Subject: How security holes happen
In-Reply-To: <lf5e4d$lfm$1@ger.gmane.org>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
Message-ID: <53164A72.3050806@stoneleaf.us>

On 03/04/2014 12:47 PM, Ned Batchelder wrote:
> On 3/4/14 12:16 PM, Skip Montanaro wrote:
>> On Tue, Mar 4, 2014 at 11:07 AM, Chris Angelico <rosuav at gmail.com> wrote:
>>> I don't have time to watch an hour-long video... what'd he do,
>>> exactly that?
>>
>> If you fast forward to 16:14, his talk is about five minutes long. He
>> wrote a Lisp compiler whose backend is Python.
>>
>> Skip
>>
>
> It's Hy: http://hylang.org

Okay, that looks totally cool.  Maybe I'll finally get a handle on LISP!  :)

--
~Ethan~



From rosuav at gmail.com  Tue Mar  4 17:44:03 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 09:44:03 +1100
Subject: find and replace string in binary file
In-Reply-To: <lf4jrk$95v$1@ger.gmane.org>
References: <01951a7d-2ab3-4203-a9c5-2f79017a980d@googlegroups.com>
 <lf4jrk$95v$1@ger.gmane.org>
Message-ID: <CAPTjJmrZPr_QdejVwntYn17LSbuEp_8BsCmR5vfNU9N0PO4QYQ@mail.gmail.com>

On Wed, Mar 5, 2014 at 12:18 AM, Peter Otten <__peter__ at web.de> wrote:
> loial wrote:
>
>> How do I read a binary file, find/identify a character string and replace
>> it with another character string and write out to another file?
>>
>> Its the finding of the string in a binary file that I am not clear on.
>
> That's not possible. You have to convert either binary to string or string
> to binary before you can replace. Whatever you choose, you have to know the
> encoding of the file.

If it's actually a binary file (as in, an executable, or an image, or
something), then the *file* won't have an encoding, so you'll need to
know the encoding of the particular string you want and encode your
string to bytes.

ChrisA


From breamoreboy at yahoo.co.uk  Tue Mar  4 17:46:38 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 04 Mar 2014 22:46:38 +0000
Subject: Proper conversion of timestamp
In-Reply-To: <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
 <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
Message-ID: <lf5l47$8q4$1@ger.gmane.org>

On 04/03/2014 21:55, Igor Korot wrote:
>
> But this particular question is easy.
>

If it's easy why can't you answer it via the docs rather than ask here?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From marko at pacujo.net  Tue Mar  4 17:48:40 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 00:48:40 +0200
Subject: How security holes happen
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
Message-ID: <87d2i1mvg7.fsf@elektro.pacujo.net>

Ethan Furman <ethan at stoneleaf.us>:

> Okay, that looks totally cool. Maybe I'll finally get a handle on
> LISP! :)

Lisp is conceptually simpler than Python, but awe-inspiring. One day, it
will overtake Python, I believe.

Once you have Lisp down pat, you'll be able to appreciate <URL:
http://en.wikipedia.org/wiki/Combinatory_logic>.

The final Nirvana is reached with <URL:
http://semarch.linguistics.fas.nyu.edu/barker/Iota/>.


Marko


From oscar.j.benjamin at gmail.com  Tue Mar  4 17:54:01 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Tue, 4 Mar 2014 22:54:01 +0000
Subject: Working with the set of real numbers
In-Reply-To: <CAPTjJmpcM9vLG8pKqDtOBgMDpbo3S2N+7Dv7BAPKbhNTjOTA4g@mail.gmail.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
 <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>
 <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>
 <CAPTjJmpcM9vLG8pKqDtOBgMDpbo3S2N+7Dv7BAPKbhNTjOTA4g@mail.gmail.com>
Message-ID: <CAHVvXxSZbGFoUEzkR5Zb_NKNJQXvEzcmrJtOzKagvXUnWqVnUw@mail.gmail.com>

On 4 March 2014 22:18, Chris Angelico <rosuav at gmail.com> wrote:
> On Wed, Mar 5, 2014 at 9:02 AM, Oscar Benjamin
> <oscar.j.benjamin at gmail.com> wrote:
>> On 4 March 2014 21:18, Chris Angelico <rosuav at gmail.com> wrote:
>>> On Wed, Mar 5, 2014 at 7:55 AM, Oscar Benjamin
>>> <oscar.j.benjamin at gmail.com> wrote:
>>>
>>> epsilon = 0.0001
>>> def sqrt(n):
>>>     guess1, guess2 = 1, n
>>>     while abs(guess1-guess2) > epsilon:
>>>         guess1 = n/guess2
>>>         guess2 = (guess1 + guess2)/2
>>>    return guess1
>>
>> That's the exact same algorithm I showed! How on earth would you call
>> that brute force?
>
> It uses a lot of division. There are various refinements that can be
> done that replace some of that division with multiplication, but I'd
> have to go do some research to figure it out.

There's a description of such a method here:
http://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Iterative_methods_for_reciprocal_square_roots

I don't know whether that would work out faster (when using decimal -
for float it would probably be slower).

> Let's compare two
> versions. In the first, you set the precision (I'm talking in terms of
> REXX's "NUMERIC DIGITS" statement

I have no idea what that is.

>- anything beyond this many digits
> will be rounded (and represented exponentially, if necessary); I'm not
> sure if decimal.Decimal precision works this way) such that you get 10
> digits.

With the decimal module if you set the precision to 5 digits then it
basically represents the number in "standard form" with 5 digits .e.g:
1.2345 x 10**21.

> Each iteration requires division by a 10-digit number, which
> is an operation that takes a certain amount of time; and it's going to
> take some number of iterations to get to the final answer.
>
> Second version, you set the precision so you get 20 digits.

If we're talking about 10-20 digits then the decimal module is
overkill: just use float. The speed up from hardware arithmetic will
massively out-weigh any other performance considerations. My version
was intended to produce large numbers of digits which is when the
big-O comes in:

$ python3.3 -m timeit -s 'from root import sqrt' 'sqrt(2, 10)'
10000 loops, best of 3: 22.4 usec per loop
$ python3.3 -m timeit -s 'from root import sqrt' 'sqrt(2, 100)'
10000 loops, best of 3: 59.1 usec per loop
$ python3.3 -m timeit -s 'from root import sqrt' 'sqrt(2, 1000)'
1000 loops, best of 3: 1.15 msec per loop
$ python3.3 -m timeit -s 'from root import sqrt' 'sqrt(2, 10000)'
10 loops, best of 3: 85.9 msec per loop
$ python3.3 -m timeit -s 'from root import sqrt' 'sqrt(2, 100000)'
10 loops, best of 3: 1.59 sec per loop


Oscar


From rosuav at gmail.com  Tue Mar  4 17:57:20 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 09:57:20 +1100
Subject: How security holes happen
In-Reply-To: <87d2i1mvg7.fsf@elektro.pacujo.net>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmrnooe7-qBp9exh053_N191a_qfDv22qEzL8xFHsoJ2nA@mail.gmail.com>

On Wed, Mar 5, 2014 at 9:48 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Lisp is conceptually simpler than Python, but awe-inspiring. One day, it
> will overtake Python, I believe.
>
> The final Nirvana is reached with...

No no no. The final Nirvana is achieved when you no longer write text
at all, but simply edit an empty file. When you are done, the file is
still empty, and you have truly reached nirvana.

Either that, or you code in
http://en.wikipedia.org/wiki/Whitespace_(programming_language) ...

ChrisA


From roy at panix.com  Tue Mar  4 17:59:23 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 04 Mar 2014 17:59:23 -0500
Subject: How security holes happen
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7763.1393973842.18130.python-list@python.org>
Message-ID: <roy-8911FF.17592304032014@news.panix.com>

In article <mailman.7763.1393973842.18130.python-list at python.org>,
 Chris Angelico <rosuav at gmail.com> wrote:

> On Wed, Mar 5, 2014 at 9:48 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> > Lisp is conceptually simpler than Python, but awe-inspiring. One day, it
> > will overtake Python, I believe.
> >
> > The final Nirvana is reached with...
> 
> No no no. The final Nirvana is achieved when you no longer write text
> at all, but simply edit an empty file. When you are done, the file is
> still empty, and you have truly reached nirvana.
> 
> Either that, or you code in
> http://en.wikipedia.org/wiki/Whitespace_(programming_language) ...
> 
> ChrisA

Man, imagine what you could do with a Unicode version of Whitespace?


From rosuav at gmail.com  Tue Mar  4 18:01:27 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 10:01:27 +1100
Subject: Working with the set of real numbers
In-Reply-To: <CAHVvXxSZbGFoUEzkR5Zb_NKNJQXvEzcmrJtOzKagvXUnWqVnUw@mail.gmail.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
 <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>
 <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>
 <CAPTjJmpcM9vLG8pKqDtOBgMDpbo3S2N+7Dv7BAPKbhNTjOTA4g@mail.gmail.com>
 <CAHVvXxSZbGFoUEzkR5Zb_NKNJQXvEzcmrJtOzKagvXUnWqVnUw@mail.gmail.com>
Message-ID: <CAPTjJmrf4-oEVKipFBYYhVNsCg-b-G0T2JKFj3ZtiYbnK7SdVw@mail.gmail.com>

On Wed, Mar 5, 2014 at 9:54 AM, Oscar Benjamin
<oscar.j.benjamin at gmail.com> wrote:
>> Let's compare two
>> versions. In the first, you set the precision (I'm talking in terms of
>> REXX's "NUMERIC DIGITS" statement
>
> I have no idea what that is.
>
>>- anything beyond this many digits
>> will be rounded (and represented exponentially, if necessary); I'm not
>> sure if decimal.Decimal precision works this way) such that you get 10
>> digits.
>
> With the decimal module if you set the precision to 5 digits then it
> basically represents the number in "standard form" with 5 digits .e.g:
> 1.2345 x 10**21.

That's how NUMERIC DIGITS works, so we're on the same page. I'm not
familiar enough with decimal.Decimal and how precision is configured,
but it seems to function the same way.

>> Each iteration requires division by a 10-digit number, which
>> is an operation that takes a certain amount of time; and it's going to
>> take some number of iterations to get to the final answer.
>>
>> Second version, you set the precision so you get 20 digits.
>
> If we're talking about 10-20 digits then the decimal module is
> overkill: just use float. The speed up from hardware arithmetic will
> massively out-weigh any other performance considerations.

Yeah, I'm just digging into the algorithm. The same concept applies
when going from 100 to 200 digits, or 1000 to 2000, and in each case,
the division will get way slower, but the number of iterations won't
go up as fast as I thought it would.

In theory, it should be possible to do the first few divisions at
lower precision, and scale up as you have need. In practice, would the
churning of precisions mean that you lose all the benefit?

ChrisA


From notbob at nothome.com  Tue Mar  4 18:03:13 2014
From: notbob at nothome.com (notbob)
Date: 4 Mar 2014 23:03:13 GMT
Subject: Geezer learns python
Message-ID: <bnn4dhFcq4jU2@mid.individual.net>

I'm trying to learn python.  I'm doing it via Zed Shaw's Learn Python
the Hard Way.  Sure enough, 16 lessons in and I've run aground.  Is it
OK for a painfully stupid ol' fart to ask painfully stupid noob
questions, here?  I'm a long time usenet fan and prefer it to irc.

I've run Slackware for many yrs and know jes enough bash to get the
drift of a slack script, but am no programmer, not by any stretch of
the imagination.  I really wanna succeed on this one and have signed
up for an online python class from Rice U.  I'd like to finish Zed's
tutorial by the 24th of this month.  I'm retired, so have the time to
burn.  Thnx.  ;)

nb


From toby at tobiah.org  Tue Mar  4 18:05:52 2014
From: toby at tobiah.org (Tobiah)
Date: Tue, 04 Mar 2014 15:05:52 -0800
Subject: Geezer learns python
In-Reply-To: <bnn4dhFcq4jU2@mid.individual.net>
References: <bnn4dhFcq4jU2@mid.individual.net>
Message-ID: <53165C50.6030602@tobiah.org>

On 03/04/2014 03:03 PM, notbob wrote:
> I'm trying to learn python.  I'm doing it via Zed Shaw's Learn Python
> the Hard Way.  Sure enough, 16 lessons in and I've run aground.  Is it
> OK for a painfully stupid ol' fart to ask painfully stupid noob
> questions, here?  I'm a long time usenet fan and prefer it to irc.
>
> I've run Slackware for many yrs and know jes enough bash to get the
> drift of a slack script, but am no programmer, not by any stretch of
> the imagination.  I really wanna succeed on this one and have signed
> up for an online python class from Rice U.  I'd like to finish Zed's
> tutorial by the 24th of this month.  I'm retired, so have the time to
> burn.  Thnx.  ;)
>
> nb
>

All are welcome here.  Try to narrow down the focus of the
question, and where applicable, post source code and program
output.




From rosuav at gmail.com  Tue Mar  4 18:10:47 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 10:10:47 +1100
Subject: Geezer learns python
In-Reply-To: <bnn4dhFcq4jU2@mid.individual.net>
References: <bnn4dhFcq4jU2@mid.individual.net>
Message-ID: <CAPTjJmrqY393uB46BmpwEcD3tHZ59_7-G9A_Hm82DxW1Hz0NBg@mail.gmail.com>

On Wed, Mar 5, 2014 at 10:03 AM, notbob <notbob at nothome.com> wrote:
> I'm trying to learn python.  I'm doing it via Zed Shaw's Learn Python
> the Hard Way.  Sure enough, 16 lessons in and I've run aground.  Is it
> OK for a painfully stupid ol' fart to ask painfully stupid noob
> questions, here?  I'm a long time usenet fan and prefer it to irc.

Yep! Either here or on the python-tutor list:

https://mail.python.org/mailman/listinfo/tutor

Just remember to give your question a good subject line, and have all
the necessary details there. This is long, but if you want to know how
to "get the most" out of a community like this, consider this to be
the cheat modes. IDKFA!

http://www.catb.org/esr/faqs/smart-questions.html

ChrisA


From torriem at gmail.com  Tue Mar  4 18:11:31 2014
From: torriem at gmail.com (Michael Torrie)
Date: Tue, 04 Mar 2014 16:11:31 -0700
Subject: Geezer learns python
In-Reply-To: <bnn4dhFcq4jU2@mid.individual.net>
References: <bnn4dhFcq4jU2@mid.individual.net>
Message-ID: <53165DA3.3020400@gmail.com>

On 03/04/2014 04:03 PM, notbob wrote:
> I'm trying to learn python.  I'm doing it via Zed Shaw's Learn Python
> the Hard Way.  Sure enough, 16 lessons in and I've run aground.  Is it
> OK for a painfully stupid ol' fart to ask painfully stupid noob
> questions, here?  I'm a long time usenet fan and prefer it to irc.
> 
> I've run Slackware for many yrs and know jes enough bash to get the
> drift of a slack script, but am no programmer, not by any stretch of
> the imagination.  I really wanna succeed on this one and have signed
> up for an online python class from Rice U.  I'd like to finish Zed's
> tutorial by the 24th of this month.  I'm retired, so have the time to
> burn.  Thnx.  ;)

I say, fire away.  I think you'll find a decent reception here.


From davea at davea.name  Tue Mar  4 18:20:20 2014
From: davea at davea.name (Dave Angel)
Date: Tue, 4 Mar 2014 18:20:20 -0500 (EST)
Subject: Working with the set of real numbers
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
 <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>
 <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>
Message-ID: <lf5mr8$ttr$1@ger.gmane.org>

 Oscar Benjamin <oscar.j.benjamin at gmail.com> Wrote in message:
> On 4 March 2014 21:18, Chris Angelico <rosuav at gmail.com> wrote:
>
> 
> It does not take O(n*n) time. This is Newton iteration and for
> well-behaved problems such as this it generates more than n digits
> after n iterations. I modified my code to show the error (x**2 - y) at
> each iteration:
> 
> $ python3.3 root.py
> 2
> 0.2
> 0.007
> 0.000006
> 5E-12
> 3E-24
> 8E-49
> 8E-98
> 8E-196
> 9E-392
> 1E-783
> 
> The number of correct digits doubles at each iteration so after n
> iterations you have 2**n digits (I misstated this as n**2 before).
> This means that it takes log(N) iterations to get N digits. See here
> for more:
> http://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method
> 
> See also the section below that:
> http://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Digit-by-digit_calculation
> 
>> That's the baseline against which anything else can be
>> compared. There are plenty of better ways to calculate them.
> 
> Such as?
> 

One problem with complexity claims is that it's easy to miss some
 contributing time eaters. I haven't done any measuring on modern
 machines nor in python, but I'd assume that multiplies take
 *much* longer for large integers, and that divides are much
 worse. So counting iterations isn't the whole story.
 

On the assumption that division by 2 is very fast,  and that a
 general multiply isn't too bad, you could improve on Newton by
 observing that the slope is 2.

   err = n - guess * guess
    guess += err/2

Some 37 years ago I microcoded  a math package which included
 square root.  All the math was decimal, and there was no hardware
 multiply or divide. The algorithm I came up with generated the
 answer one digit at a time, with no subsequent rounding needed.
 And it took just a little less time than two divides. For that
 architecture,  Newton's method would've been too
 slow.

Incidentally, the algorithm did no divides, not even by 2. No
 multiplies either.  Just repeated subtraction,  sorta like divide
 was done.

If anyone is curious,  I'll be glad to describe the algorithm; 
 I've never seen it published, before or since.  I got my
 inspiration from a method used in mechanical,  non-motorized, 
 adding machines.  My father had shown me that approach in the
 50's. 



-- 
DaveA



From breamoreboy at yahoo.co.uk  Tue Mar  4 18:16:48 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 04 Mar 2014 23:16:48 +0000
Subject: How security holes happen
In-Reply-To: <roy-8911FF.17592304032014@news.panix.com>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7763.1393973842.18130.python-list@python.org>
 <roy-8911FF.17592304032014@news.panix.com>
Message-ID: <lf5msq$ui6$1@ger.gmane.org>

On 04/03/2014 22:59, Roy Smith wrote:
> In article <mailman.7763.1393973842.18130.python-list at python.org>,
>   Chris Angelico <rosuav at gmail.com> wrote:
>
>> On Wed, Mar 5, 2014 at 9:48 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> Lisp is conceptually simpler than Python, but awe-inspiring. One day, it
>>> will overtake Python, I believe.
>>>
>>> The final Nirvana is reached with...
>>
>> No no no. The final Nirvana is achieved when you no longer write text
>> at all, but simply edit an empty file. When you are done, the file is
>> still empty, and you have truly reached nirvana.
>>
>> Either that, or you code in
>> http://en.wikipedia.org/wiki/Whitespace_(programming_language) ...
>>
>> ChrisA
>
> Man, imagine what you could do with a Unicode version of Whitespace?
>

Yes, but how do we pursuade the Python core devs to give us a decent 
implementation?  Let's face it, according to our resident unicode 
expert, they can't get anything right about unicode.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Tue Mar  4 18:22:49 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 10:22:49 +1100
Subject: How security holes happen
In-Reply-To: <lf5msq$ui6$1@ger.gmane.org>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7763.1393973842.18130.python-list@python.org>
 <roy-8911FF.17592304032014@news.panix.com>
 <lf5msq$ui6$1@ger.gmane.org>
Message-ID: <CAPTjJmog_NKRajbzZ28R0OGnrXr3jJeNxAu+=ueonkGsuG1Mxw@mail.gmail.com>

On Wed, Mar 5, 2014 at 10:16 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>> Man, imagine what you could do with a Unicode version of Whitespace?
>>
>
> Yes, but how do we pursuade the Python core devs to give us a decent
> implementation?  Let's face it, according to our resident unicode expert,
> they can't get anything right about unicode.

Easy. We get him to implement it.

ChrisA


From breamoreboy at yahoo.co.uk  Tue Mar  4 18:27:07 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 04 Mar 2014 23:27:07 +0000
Subject: Geezer learns python
In-Reply-To: <bnn4dhFcq4jU2@mid.individual.net>
References: <bnn4dhFcq4jU2@mid.individual.net>
Message-ID: <lf5ng5$63p$1@ger.gmane.org>

On 04/03/2014 23:03, notbob wrote:
> I'm trying to learn python.  I'm doing it via Zed Shaw's Learn Python
> the Hard Way.  Sure enough, 16 lessons in and I've run aground.  Is it
> OK for a painfully stupid ol' fart to ask painfully stupid noob
> questions, here?  I'm a long time usenet fan and prefer it to irc.
>
> I've run Slackware for many yrs and know jes enough bash to get the
> drift of a slack script, but am no programmer, not by any stretch of
> the imagination.  I really wanna succeed on this one and have signed
> up for an online python class from Rice U.  I'd like to finish Zed's
> tutorial by the 24th of this month.  I'm retired, so have the time to
> burn.  Thnx.  ;)
>
> nb
>

You might feel more comfortable on the tutor mailing list 
https://mail.python.org/mailman/listinfo/tutor

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From breamoreboy at yahoo.co.uk  Tue Mar  4 18:40:10 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 04 Mar 2014 23:40:10 +0000
Subject: How security holes happen
In-Reply-To: <CAPTjJmog_NKRajbzZ28R0OGnrXr3jJeNxAu+=ueonkGsuG1Mxw@mail.gmail.com>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7763.1393973842.18130.python-list@python.org>
 <roy-8911FF.17592304032014@news.panix.com> <lf5msq$ui6$1@ger.gmane.org>
 <CAPTjJmog_NKRajbzZ28R0OGnrXr3jJeNxAu+=ueonkGsuG1Mxw@mail.gmail.com>
Message-ID: <lf5o8j$bno$1@ger.gmane.org>

On 04/03/2014 23:22, Chris Angelico wrote:
> On Wed, Mar 5, 2014 at 10:16 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>>> Man, imagine what you could do with a Unicode version of Whitespace?
>>>
>>
>> Yes, but how do we pursuade the Python core devs to give us a decent
>> implementation?  Let's face it, according to our resident unicode expert,
>> they can't get anything right about unicode.
>
> Easy. We get him to implement it.
>
> ChrisA
>

Bingo, nail struck firmly on head with steam roller :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From greg.ewing at canterbury.ac.nz  Tue Mar  4 18:57:00 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 05 Mar 2014 12:57:00 +1300
Subject: Functional programming
In-Reply-To: <87ppm1myhi.fsf@elektro.pacujo.net>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>	<mailman.7641.1393855219.18130.python-list@python.org>	<216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>	<mailman.7644.1393856584.18130.python-list@python.org>	<0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>	<mailman.7647.1393858917.18130.python-list@python.org>	<5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>	<mailman.7651.1393871851.18130.python-list@python.org>	<5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>	<mailman.7695.1393913099.18130.python-list@python.org>	<53159540$0$2923$c3e8da3$76491128@news.astraweb.com>	<mailman.7700.1393930643.18130.python-list@python.org>	<87bnxloibq.fsf@elektro.pacujo.net>	<mailman.7737.1393963318.18130.python-list@python.org>	<8738ixofhl.fsf@elektro.pacujo.net>	<mailman.7741.1393967180.18130.python-list@python.org>	<87txbdmzh3.fsf@elektro.pacujo.net>	<mailman.7743.1393968417.18130.python-list@python.org>
 <87ppm1myhi.fsf@elektro.pacujo.net>
Message-ID: <bnn7idFdlqhU1@mid.individual.net>

Marko Rauhamaa wrote:
> Python doesn't have anonymous inner classes, but it has named inner
> classes, and that's quite sufficient.

I would say it's Python's closures that make up for
not having Java's inner classes.

Or to put it another way, inner classes are Java's
kludgy way of working around a lack of closures.

-- 
Greg


From cs at zip.com.au  Tue Mar  4 19:07:37 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Wed, 5 Mar 2014 11:07:37 +1100
Subject: How security holes happen
In-Reply-To: <CAPTjJmrnooe7-qBp9exh053_N191a_qfDv22qEzL8xFHsoJ2nA@mail.gmail.com>
References: <CAPTjJmrnooe7-qBp9exh053_N191a_qfDv22qEzL8xFHsoJ2nA@mail.gmail.com>
Message-ID: <20140305000737.GA9013@cskk.homeip.net>

On 05Mar2014 09:57, Chris Angelico <rosuav at gmail.com> wrote:
> On Wed, Mar 5, 2014 at 9:48 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> > Lisp is conceptually simpler than Python, but awe-inspiring. One day, it
> > will overtake Python, I believe.
> >
> > The final Nirvana is reached with...
> 
> No no no. The final Nirvana is achieved when you no longer write text
> at all, but simply edit an empty file. When you are done, the file is
> still empty, and you have truly reached nirvana.

  Every program has at least one bug and can be shortened by at least one
  instruction -- from which, by induction, it is evident that every
  program can be reduced to one instruction that does not work.
        - Ken Arnold

Cheers,
Cameron Simpson <cs at zip.com.au>


From emile at fenx.com  Tue Mar  4 19:13:00 2014
From: emile at fenx.com (emile)
Date: Tue, 04 Mar 2014 16:13:00 -0800
Subject: find and replace string in binary file
In-Reply-To: <CAPTjJmrZPr_QdejVwntYn17LSbuEp_8BsCmR5vfNU9N0PO4QYQ@mail.gmail.com>
References: <01951a7d-2ab3-4203-a9c5-2f79017a980d@googlegroups.com>
 <lf4jrk$95v$1@ger.gmane.org>
 <CAPTjJmrZPr_QdejVwntYn17LSbuEp_8BsCmR5vfNU9N0PO4QYQ@mail.gmail.com>
Message-ID: <lf5q63$49r$1@ger.gmane.org>

On 03/04/2014 02:44 PM, Chris Angelico wrote:
> On Wed, Mar 5, 2014 at 12:18 AM, Peter Otten <__peter__ at web.de> wrote:
>> loial wrote:
>>
>>> How do I read a binary file, find/identify a character string and replace
>>> it with another character string and write out to another file?
>>>
>>> Its the finding of the string in a binary file that I am not clear on.
>>
>> That's not possible. You have to convert either binary to string or string
>> to binary before you can replace. Whatever you choose, you have to know the
>> encoding of the file.
>
> If it's actually a binary file (as in, an executable, or an image, or
> something), then the *file* won't have an encoding, so you'll need to
> know the encoding of the particular string you want and encode your
> string to bytes.


On 2.7 it's as easy as it sounds without having to think much about 
encodings and such.  I find it mostly just works.

emile at paj39:~$ which python
/usr/bin/python
emile at paj39:~$ python
Python 2.7.3 (default, Sep 26 2013, 16:38:10)
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
 >>> image = open('/usr/bin/python','rb').read()
 >>> image.find("""Type "help", "copyright", "credits" """)
1491592
 >>> image = image[:1491592]+"Echo"+image[1491592+4:]
 >>> open('/home/emile/pyecho','wb').write(image)
 >>>
emile at paj39:~$ chmod a+x /home/emile/pyecho
emile at paj39:~$ /home/emile/pyecho
Python 2.7.3 (default, Sep 26 2013, 16:38:10)
[GCC 4.7.2] on linux2
Echo "help", "copyright", "credits" or "license" for more information.

YMMV,

Emile




From marko at pacujo.net  Tue Mar  4 19:11:05 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 02:11:05 +0200
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <87bnxloibq.fsf@elektro.pacujo.net>
 <mailman.7737.1393963318.18130.python-list@python.org>
 <8738ixofhl.fsf@elektro.pacujo.net>
 <mailman.7741.1393967180.18130.python-list@python.org>
 <87txbdmzh3.fsf@elektro.pacujo.net>
 <mailman.7743.1393968417.18130.python-list@python.org>
 <87ppm1myhi.fsf@elektro.pacujo.net> <bnn7idFdlqhU1@mid.individual.net>
Message-ID: <878uspmrmu.fsf@elektro.pacujo.net>

Gregory Ewing <greg.ewing at canterbury.ac.nz>:

> Marko Rauhamaa wrote:
>> Python doesn't have anonymous inner classes, but it has named inner
>> classes, and that's quite sufficient.
>
> I would say it's Python's closures that make up for not having Java's
> inner classes.
>
> Or to put it another way, inner classes are Java's kludgy way of
> working around a lack of closures.

I actually quite like Java's inner classes. In fact, I think introducing
lambdas into Java was a grave mistake; the silly competitive pressure
from C# made them accept a very ugly and disheveled syntax.

Inner classes *are* closures. They are more general than (Lisp-style)
lambda's because they accept more than one method.

Python, of course, has all of the above.


Marko


From galaxyblue63 at gmail.com  Tue Mar  4 19:14:20 2014
From: galaxyblue63 at gmail.com (Bill)
Date: Tue, 4 Mar 2014 16:14:20 -0800 (PST)
Subject: How to create an instance of a python class from C++
Message-ID: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>

Hello:

I can't figure out how to create an instance
of a python class from 'C++':

( I am relatively new to Python so excuse some of
  the following. )

In a .py file I create an ABC and then specialize it:

    from MyMod import *
    from abc import ABCMeta, abstractmethod

    # Declare an abstract base class.
    class Base(metaclass=ABCMeta):
        """Base class."""
        @abstractmethod
        def description(self):
            return "From the base class."

    # Declare a class that inerits from the base.
    class Derived(Base):
        """Derived class."""
        def description(self):
            return "From the Derived."

    # Register the derived class.
    RegisterClass(Derived)

Then from 'C++' (my implementation of RegisterClass)
I try to create an instance

    static PyObject *
    RegisterClass( PyObject *, PyObject *args ) {       // This gets called ok.

        PyObject *class_decl;
        if( ! PyArg_ParseTuple(args, "O", &class_decl) )
            return NULL;
        Py_INCREF(class_decl);

        PyTypeObject *typ = class_decl->ob_type;

        // Tried this.
        // PyObject *an = _PyObject_New(class_decl->ob_type); assert(an);
        // PyObject *desc = PyObject_CallMethod(an,"description",NULL); assert(desc);

        // Tried this.
        // PyObject *an = PyType_GenericNew((PyTypeObject *)class_decl->ob_type, NULL, NULL); assert(an);
        // assert(class_decl); assert(class_decl->ob_type); assert(class_decl->ob_type->tp_new);

        // This returns something.
        assert(class_decl); assert(class_decl->ob_type); assert(class_decl->ob_type->tp_new);
        PyObject *an_inst = class_decl->ob_type->tp_new(class_decl->ob_type,NULL, NULL); assert(an_inst);
        assert(class_decl->ob_type->tp_init);

        // This crashes.
        int ret = class_decl->ob_type->tp_init(an_inst,NULL, NULL); assert(ret == 0);
        // PyObject_CallMethod(an_inst,"__init__",NULL);
        // PyObject *an_inst = PyObject_CallMethod(class_decl,"__new__",NULL); assert(an_inst);

        // Never get here.
        PyObject *desc = PyObject_CallMethod(an_inst,"description",NULL); assert(desc);
        char *cp = _PyUnicode_AsString(desc);
        cerr << "Description:" << cp << endl;

        return PyLong_FromLong(0);
    }

    static PyMethodDef MyModMethods[] = {
        { "RegisterClass", RegisterClass, METH_VARARGS, "Register class." },
        {  NULL,           NULL,          0,             NULL             }
    };

    static struct PyModuleDef MyModMod = {
       PyModuleDef_HEAD_INIT,
       "MyMod",            // name of module
       NULL,                // module documentation, may be NULL
       -1,
       MyModMethods,
       NULL,
       NULL,
       NULL,
       NULL
    };

    PyMODINIT_FUNC
    PyInit_MyMod( void ) {
        PyObject* m = PyModule_Create(&MyModMod);
        if( m == NULL )
            return NULL;
            return m;
    }

    int
    main( int, char ** ) {

        PyImport_AppendInittab( "MyMod", PyInit_MyMod );

        Py_Initialize();

        const char *file_name = "z.py";
        FILE *fp = fopen(file_name,"r");
        if( fp ) {
            PyRun_SimpleFileExFlags(fp,file_name,1,0);
        }

        Py_Finalize();

        return 0;
    }


From rhodri at wildebst.org.uk  Tue Mar  4 19:25:36 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Wed, 05 Mar 2014 00:25:36 -0000
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au>
 <mailman.7663.1393882574.18130.python-list@python.org>
 <87wqgb6imm.fsf@elektro.pacujo.net>
 <mailman.7671.1393885206.18130.python-list@python.org>
 <KwiRu.19$Cd2.6@fx19.am4>
 <5315bd9e$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <op.xb73gypp5079vu@gnudebeest>

On Tue, 04 Mar 2014 11:48:46 -0000, Steven D'Aprano  
<steve+comp.lang.python at pearwood.info> wrote:

> On Tue, 04 Mar 2014 11:10:34 +0000, Alister wrote:
>
>> Definition of insanity
>>
>> Doing the same thing over and over again & expecting different results
>
> *rolls dice*

As any gamer will tell you, dice are not random number generators.  They  
are far too cussed for that :-)


-- 
Rhodri James *-* Wildebeest Herder to the Masses


From python at mrabarnett.plus.com  Tue Mar  4 19:42:51 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 05 Mar 2014 00:42:51 +0000
Subject: Proper conversion of timestamp
In-Reply-To: <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
 <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
Message-ID: <5316730B.3080706@mrabarnett.plus.com>

On 2014-03-04 21:55, Igor Korot wrote:
> Hi, Mark,
>
>
> On Tue, Mar 4, 2014 at 1:44 PM, Mark Lawrence <breamoreboy at yahoo.co.uk
> <mailto:breamoreboy at yahoo.co.uk>> wrote:
>
>     On 04/03/2014 20:57, Igor Korot wrote:
>
>         Hi, ALL,
>         I'm getting this:
>
>         timestamp out of range for platform localtime()/gmtime() function
>
>         trying to convert the timestamp with milliseconds into the
>         datetime object.
>
>         The first hit of Google gives me this:
>
>         http://stackoverflow.com/__questions/12458595/convert-__epoch-timestamp-in-python
>         <http://stackoverflow.com/questions/12458595/convert-epoch-timestamp-in-python>
>
>         but the solution described is not good for me since it does not
>         gives
>         me the milliseconds value.
>
>         How do I get the proper datetime value including milliseconds
>         from the
>         timestamp?
>
>         Thank you.
>
>
>     You have a long record of asking timestamp related questions so you
>     should know where the docs are that provide the answer to this
>     question.  I'll leave you to go off and read them.  If you don't
>     understand them, please cut and paste your code here, state what you
>     expected to happen, what actually happened, including any traceback
>     if applicable, and then we'll be happy to point you the error of
>     your ways.
>
>
> Working with the dates is not that easy and not just in Python.
> There are too many different formatting involved with many different
> representation.
> And on top of it it is possible to use one system in completely
> different environment.
>
> But this particular question is easy.
>
> What I have is a timestamp which reads: 1289410678L.
>
That's an integer. It looks like the timestamp is a whole number of
seconds, so the number of milliseconds is 0. (I make it '2010-11-10
17:37:58'.)

> Trying to convert this into the datetime object in Python using:
>
> import datetime
> datetime.datetime.fromtimestamp( stamp )
>
> produces the error: timestamp out of range for platform
> localtime()/gmtime() function.
>
> This is because this timestamp is not in seconds, but rather in
> milliseconds.
>
> Now the question I have is: how do I properly convert this timestamp
> into the datetime object with the milliseconds?
>
Using the datetime's .strftime method, you can include the number of
microseconds in the format with '%f' (it'll write the microseconds as 6
digits).

If you want it to the nearest millisecond (the timestamp would be a
float), you could round the timestamp to 3 decimal places, use the '%f'
in the format, and then truncate the string result to remove the last 3
digits.



From root at 127.0.0.1  Tue Mar  4 19:52:31 2014
From: root at 127.0.0.1 (Andrew Cooper)
Date: Wed, 05 Mar 2014 00:52:31 +0000
Subject: How security holes happen
In-Reply-To: <mailman.7670.1393885170.18130.python-list@python.org>
References: <lf22t1$sgh$1@ger.gmane.org>
 <mailman.7670.1393885170.18130.python-list@python.org>
Message-ID: <izuRu.12475$wf3.1354@fx10.am4>

On 03/03/2014 22:19, Cameron Simpson wrote:
> On 03Mar2014 09:17, Neal Becker <ndbecker2 at gmail.com> wrote:
>>  Charles R Harris <charlesr.harris at gmail.com> Wrote in message:
>>>
>>
>> Imo the lesson here is never write in low level c. Use modern
>>  languages with well designed exception handling.
> 
> What, and rely on someone else's low level C?
> 

Why is C the lowest denominator?

Even with correctly written C and assembly, how can you be sure that
your processor is executing the SYSRET instruction safely?
(CVE-2012-0217 for anyone interested)

~Andrew


From rhodri at wildebst.org.uk  Tue Mar  4 20:08:57 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Wed, 05 Mar 2014 01:08:57 -0000
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
Message-ID: <op.xb75g7ap5079vu@gnudebeest>

On Tue, 04 Mar 2014 05:24:03 -0000, Chris Angelico <rosuav at gmail.com>  
wrote:

> Code should look like its intent. Warping it around performance is
> hardly ever worthwhile.

That depends.  In Python, I'd agree with you; if I'm worrying about  
performance in Python, I'm worrying at the level of the algorithms I'm  
using.  In a constrained embedded C environment, which is where I spend  
most of my working life, writing your code so that the compiler chooses  
the right optimisation is critical.  Sometimes it matters a great deal to  
me that something like "x *= 5" compiles to a single ARM instruction, or  
that splitting a loop into two to avoid a conditional test will let an  
DSP's optimiser double the speed of a section of code.

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From ian.g.kelly at gmail.com  Tue Mar  4 20:55:04 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 4 Mar 2014 18:55:04 -0700
Subject: How to create an instance of a python class from C++
In-Reply-To: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>
References: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>
Message-ID: <CALwzid=T2Twmh4Ynh+EK5J97rqKZehqsS2M3uWdk1ShpaRif4w@mail.gmail.com>

On Tue, Mar 4, 2014 at 5:14 PM, Bill <galaxyblue63 at gmail.com> wrote:
> Hello:
>
> I can't figure out how to create an instance
> of a python class from 'C++':
>
> ( I am relatively new to Python so excuse some of
>   the following. )
>
> In a .py file I create an ABC and then specialize it:

Why are you creating an ABC?  Most Python classes do not use them.
Maybe you have a reason for it, but it's irrelevant to what you're
currently trying to do.

> Then from 'C++' (my implementation of RegisterClass)
> I try to create an instance
>
>     static PyObject *
>     RegisterClass( PyObject *, PyObject *args ) {       // This gets called ok.
>
>         PyObject *class_decl;
>         if( ! PyArg_ParseTuple(args, "O", &class_decl) )
>             return NULL;
>         Py_INCREF(class_decl);

So far, so good.  The object that was passed in was the "Derived"
class object.  Since you presumably only want class objects to be
passed in, you might want to check that here using PyType_Check.

>         PyTypeObject *typ = class_decl->ob_type;

Okay, now if class_decl is the class object that was passed in, then
class_decl->ob_type is the *type* of that class object -- the
metaclass, which in this case would be ABCMeta.  You probably don't
need this, because you want to instantiate Derived, not ABCMeta.

>         // Tried this.
>         // PyObject *an = _PyObject_New(class_decl->ob_type); assert(an);
>         // PyObject *desc = PyObject_CallMethod(an,"description",NULL); assert(desc);

In Python, you instantiate a class by calling it.  You should do the
same in C, using PyObject_CallFunction.  But as above, note that you
want to call class_decl, not class_decl->ob_type.

PyObject_New doesn't do any initialization and is, I believe, meant to
be used when implementing types in C.


From roy at panix.com  Tue Mar  4 20:57:43 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 04 Mar 2014 20:57:43 -0500
Subject: How security holes happen
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
Message-ID: <roy-4E7DBB.20574304032014@news.panix.com>

In article <mailman.7777.1393980007.18130.python-list at python.org>,
 Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:

> On Wed, 05 Mar 2014 00:48:40 +0200, Marko Rauhamaa <marko at pacujo.net>
> declaimed the following:
> 
> >Ethan Furman <ethan at stoneleaf.us>:
> >
> >> Okay, that looks totally cool. Maybe I'll finally get a handle on
> >> LISP! :)
> >
> >Lisp is conceptually simpler than Python, but awe-inspiring. One day, it
> >will overtake Python, I believe.

I first played with Lisp in 1976.  The only time I ever used it for 
anything serious was an A/I course I took in the mid 80's.  At the end 
of the semester, I was just starting to write things in Lisp (as opposed 
to writing C transliterated to Lisp syntax and keywords).

>  It's already had 54 years to become a major language...
> 
>  Instead it has schismed into Common Lisp and Scheme (and a few other
> dialects)

Python has had 23 years to become a major language...

Instead it has schismed into Python 2.x and Python 3.x.

[holding hands over ears to avoid the howls of derision, while ducking 
and running]


From roy at panix.com  Tue Mar  4 21:09:17 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 04 Mar 2014 21:09:17 -0500
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
Message-ID: <roy-A9E76C.21091704032014@news.panix.com>

In article <op.xb75g7ap5079vu at gnudebeest>,
 "Rhodri James" <rhodri at wildebst.org.uk> wrote:

> On Tue, 04 Mar 2014 05:24:03 -0000, Chris Angelico <rosuav at gmail.com>  
> wrote:
> 
> > Code should look like its intent. Warping it around performance is
> > hardly ever worthwhile.
> 
> That depends.  In Python, I'd agree with you; if I'm worrying about  
> performance in Python, I'm worrying at the level of the algorithms I'm  
> using.  In a constrained embedded C environment, which is where I spend  
> most of my working life, writing your code so that the compiler chooses  
> the right optimisation is critical.  Sometimes it matters a great deal to  
> me that something like "x *= 5" compiles to a single ARM instruction, or  
> that splitting a loop into two to avoid a conditional test will let an  
> DSP's optimiser double the speed of a section of code.

Yeah.  BTDT.  I've stolen the bottom three bits of a pointer for my own 
use because I know everything is 64-bit aligned so it's all zeros 
anyway.  I feel like there must be some organization I should be going 
to every month that meets in a church basement and I can get up in front 
of the room and say, "Hi, my name is Roy and I'm a C++ hacker", and have 
everybody be supportive.

I mostly live in the Python world these days, where I'm firmly in the 
camp of, "Stay away from O(n^2) and don't hit the database with 
unindexed queries, and you're probably good".  But, that's because we 
push most of the hard work off onto C and C++ code that is written by 
guys who worry about the bottom three bits.

One of those really awesome tools is haproxy.  It's just amazing how 
fast (and stable) that thing is.  It's all written in C.  Most of the if 
statements are decorated with #pragmas telling the compiler which branch 
is the most likely to be taken, so it can optimize better.  We need 
people like that down in the trenches, so the rest of us can run around 
naked in the park with flowers in our hair and not worry about the 
bottom three bits any more.


From ikorot01 at gmail.com  Tue Mar  4 21:13:43 2014
From: ikorot01 at gmail.com (Igor Korot)
Date: Tue, 4 Mar 2014 18:13:43 -0800
Subject: Proper conversion of timestamp
In-Reply-To: <lf5l47$8q4$1@ger.gmane.org>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
 <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
 <lf5l47$8q4$1@ger.gmane.org>
Message-ID: <CA+FnnTzEBV2Zh-nMY7AgCbEH57uj6wVt6x5Fch-oeZmqHRTDng@mail.gmail.com>

Hi, Mark,

On Tue, Mar 4, 2014 at 2:46 PM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> On 04/03/2014 21:55, Igor Korot wrote:
>>
>>
>> But this particular question is easy.
>>
>
> If it's easy why can't you answer it via the docs rather than ask here?

What I meant to say is: it is easy for all you people and it is
definitely easier than
trying to figure out how to process and display different dates.

Thank you.

>
>
> --
> My fellow Pythonistas, ask not what our language can do for you, ask what
> you can do for our language.
>
> Mark Lawrence
>
> ---
> This email is free from viruses and malware because avast! Antivirus
> protection is active.
> http://www.avast.com
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list


From ikorot01 at gmail.com  Tue Mar  4 21:19:48 2014
From: ikorot01 at gmail.com (Igor Korot)
Date: Tue, 4 Mar 2014 18:19:48 -0800
Subject: Proper conversion of timestamp
In-Reply-To: <5316730B.3080706@mrabarnett.plus.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
 <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
 <5316730B.3080706@mrabarnett.plus.com>
Message-ID: <CA+FnnTyvXW83OR-L78Xqx5gttv1BANiNHUGh7r5XFJkJ-bGedA@mail.gmail.com>

MRAB,

On Tue, Mar 4, 2014 at 4:42 PM, MRAB <python at mrabarnett.plus.com> wrote:
> On 2014-03-04 21:55, Igor Korot wrote:
>>
>> Hi, Mark,
>>
>>
>> On Tue, Mar 4, 2014 at 1:44 PM, Mark Lawrence <breamoreboy at yahoo.co.uk
>> <mailto:breamoreboy at yahoo.co.uk>> wrote:
>>
>>     On 04/03/2014 20:57, Igor Korot wrote:
>>
>>         Hi, ALL,
>>         I'm getting this:
>>
>>         timestamp out of range for platform localtime()/gmtime() function
>>
>>         trying to convert the timestamp with milliseconds into the
>>         datetime object.
>>
>>         The first hit of Google gives me this:
>>
>>
>> http://stackoverflow.com/__questions/12458595/convert-__epoch-timestamp-in-python
>>
>>
>> <http://stackoverflow.com/questions/12458595/convert-epoch-timestamp-in-python>
>>
>>         but the solution described is not good for me since it does not
>>         gives
>>         me the milliseconds value.
>>
>>         How do I get the proper datetime value including milliseconds
>>         from the
>>         timestamp?
>>
>>         Thank you.
>>
>>
>>     You have a long record of asking timestamp related questions so you
>>     should know where the docs are that provide the answer to this
>>     question.  I'll leave you to go off and read them.  If you don't
>>     understand them, please cut and paste your code here, state what you
>>     expected to happen, what actually happened, including any traceback
>>     if applicable, and then we'll be happy to point you the error of
>>     your ways.
>>
>>
>> Working with the dates is not that easy and not just in Python.
>> There are too many different formatting involved with many different
>> representation.
>> And on top of it it is possible to use one system in completely
>> different environment.
>>
>> But this particular question is easy.
>>
>> What I have is a timestamp which reads: 1289410678L.
>>
> That's an integer. It looks like the timestamp is a whole number of
> seconds, so the number of milliseconds is 0. (I make it '2010-11-10
> 17:37:58'.)

Well it is this particular timestamp.
But I have a lot of files to process and some do have a timestamp with
the milliseconds.

>
>
>> Trying to convert this into the datetime object in Python using:
>>
>> import datetime
>> datetime.datetime.fromtimestamp( stamp )
>>
>> produces the error: timestamp out of range for platform
>> localtime()/gmtime() function.
>>
>> This is because this timestamp is not in seconds, but rather in
>> milliseconds.
>>
>> Now the question I have is: how do I properly convert this timestamp
>> into the datetime object with the milliseconds?
>>
> Using the datetime's .strftime method, you can include the number of
> microseconds in the format with '%f' (it'll write the microseconds as 6
> digits).
>
> If you want it to the nearest millisecond (the timestamp would be a
> float), you could round the timestamp to 3 decimal places, use the '%f'
> in the format, and then truncate the string result to remove the last 3
> digits.

Right.
The question is: how to get the number of milliseconds out of timestamp?
Once again: I can get the datetime object with the seconds precision
by dividing it on 1000. But that will produce the datetime object with
the seconds precision.

I can actually produce another timestamp with the milliseconds from a
different file...

Thank you.

>
> --
> https://mail.python.org/mailman/listinfo/python-list


From albert at spenarnc.xs4all.nl  Tue Mar  4 21:27:51 2014
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 05 Mar 2014 02:27:51 GMT
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <CAPTjJmp-iQLL_VypbMqzgHmQHiNQU-hvAgzR-zh32h05av4p4A@mail.gmail.com>
 <mailman.7702.1393932047.18130.python-list@python.org>
Message-ID: <53168ba7$0$25064$e4fe514c@dreader37.news.xs4all.nl>

In article <mailman.7702.1393932047.18130.python-list at python.org>,
Ian Kelly  <ian.g.kelly at gmail.com> wrote:
>On Mon, Mar 3, 2014 at 11:35 PM, Chris Angelico <rosuav at gmail.com> wrote:
>> In constant space, that will produce the sum of two infinite sequences
>> of digits. (And it's constant time, too, except when it gets a stream
>> of nines. Adding three thirds together will produce an infinite loop
>> as it waits to see if there'll be anything that triggers an infinite
>> cascade of carries.) Now, if there's a way to do that for square
>> rooting a number, then the CF notation has a distinct benefit over the
>> decimal expansion used here. As far as I know, there's no simple way,
>> in constant space and/or time, to progressively yield more digits of a
>> number's square root, working in decimal.
>
>The code for that looks like this:
>
>def cf_sqrt(n):
>    """Yield the terms of the square root of n as a continued fraction."""
>   m = 0
>    d = 1
>    a = a0 = floor_sqrt(n)
>    while True:
>        yield a
>        next_m = d * a - m
>        next_d = (n - next_m * next_m) // d
>        if next_d == 0:
>            break
>        next_a = (a0 + next_m) // next_d
>        m, d, a = next_m, next_d, next_a
>
>
>def floor_sqrt(n):
>    """Return the integer part of the square root of n."""
>    n = int(n)
>    if n == 0: return 0
>    lower = 2 ** int(math.log(n, 2) // 2)
>    upper = lower * 2
>    while upper - lower > 1:
>        mid = (upper + lower) // 2
>        if n < mid * mid:
>            upper = mid
>        else:
>            lower = mid
>    return lower
>
>
>The floor_sqrt function is merely doing a simple binary search and
>could probably be optimized, but then it's only called once during
>initialization anyway.  The meat of the loop, as you can see, is just
>a constant amount of integer arithmetic.  If it were desired to halt
>once the continued fraction starts to repeat, that would just be a
>matter of checking whether the triple (m, d, a) has been seen already.
>
>Going back to your example of adding generated digits though, I don't
>know how to add two continued fractions together without evaluating
>them.

That is highly non-trivial indeed. See the gosper.txt reference
I gave in another post.

Groetjes Albert
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From harrismh777 at gmail.com  Tue Mar  4 21:28:30 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Tue, 4 Mar 2014 18:28:30 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <mailman.7745.1393969211.18130.python-list@python.org>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <44cb976d-cb25-468a-8525-edbf4b539f60@googlegroups.com>
 <1ba60da3-93d4-4bca-ab96-9f94e6afe519@googlegroups.com>
 <27d19767-84ee-4ab7-87fd-784e8ac57680@googlegroups.com>
 <mailman.7745.1393969211.18130.python-list@python.org>
Message-ID: <8386c37e-239a-4c60-9fbb-0a368d0c5d82@googlegroups.com>

On Tuesday, March 4, 2014 3:35:48 PM UTC-6, Stefan Krah wrote:

> http://www.bytereef.org/mpdecimal/quickstart.html#factorial-in-pure-python

> Be sure to set MAX_EMAX and MIN_EMIN, that's missing in the example.

> http://www.bytereef.org/mpdecimal/benchmarks.html#arbitrary-precision-libraries
> Stefan Krah

hi Stefan!

   Good to hear from you, sir. My hat is off to you for sure, 
and thank you very kindly for your good work on the 
decimal.Decimal code;  ~very nice!   {hands clapping}

   Thanks for the input above, will read.

   Stay in touch. I have an expansion of my decimal idea for 
python (stay tuned on python-ideas) which I think will be
for the better, if we can convince wide adoption; could be
an up-hill climb, but who knows.

   Its been good to meet you in the code, and now a true 
pleasure to meet you on-line as well. Hope to see you sometime 
at a python convention perhaps.

Best regards,

Mark H Harris


   


From wuwei23 at gmail.com  Tue Mar  4 21:28:45 2014
From: wuwei23 at gmail.com (alex23)
Date: Wed, 05 Mar 2014 12:28:45 +1000
Subject: How do I process this?
In-Reply-To: <mailman.7690.1393905834.18130.python-list@python.org>
References: <mailman.7690.1393905834.18130.python-list@python.org>
Message-ID: <lf624v$ehb$1@dont-email.me>

On 4/03/2014 2:03 PM, Igor Korot wrote:
> Hi, ALL,
> I have a csv file which depending on how it was produced gives 2
> different strings as shown in the example below (test1 and test2).
> I am only interested in the first field in test1 and obviously in the
> whole string of test2.
>  >>> test1 = "a,,,,"
>  >>> test2 = "a"

Try using the csv module:

     >>> from StringIO import StringIO
     >>> csvfile = StringIO()
     >>> csvfile.write('a,,,,\n')
     >>> csvfile.write('a\n')
     >>> csvfile.seek(0)
     >>>
     >>> import csv
     >>> reader = csv.reader(csvfile)
     >>> [x[0] for x in reader]
     ['a', 'a']


From ben+python at benfinney.id.au  Tue Mar  4 21:33:47 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 05 Mar 2014 13:33:47 +1100
Subject: Proper conversion of timestamp
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
 <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
 <5316730B.3080706@mrabarnett.plus.com>
 <CA+FnnTyvXW83OR-L78Xqx5gttv1BANiNHUGh7r5XFJkJ-bGedA@mail.gmail.com>
Message-ID: <85siqxfk6s.fsf@benfinney.id.au>

Igor Korot <ikorot01 at gmail.com> writes:

> On Tue, Mar 4, 2014 at 4:42 PM, MRAB <python at mrabarnett.plus.com> wrote:
> >> But this particular question is easy.
> >>
> >> What I have is a timestamp which reads: 1289410678L.
> >>
> > That's an integer. It looks like the timestamp is a whole number of
> > seconds, so the number of milliseconds is 0. (I make it '2010-11-10
> > 17:37:58'.)
>
> Well it is this particular timestamp.

Which is what you presented as ?what I have?.

> But I have a lot of files to process and some do have a timestamp with
> the milliseconds.

So, if you want help with such timestamps, you'll need to present a real
example (or preferably several exmaples) of timestamps that need this
handling.

> Right.
> The question is: how to get the number of milliseconds out of
> timestamp?

>From the timestamp you showed: The number of milliseconds is zero, since
it's an integer. That datatype will *always* have zero milliseconds.

> Once again: I can get the datetime object with the seconds precision
> by dividing it on 1000. But that will produce the datetime object with
> the seconds precision.

Because that's the data you're showing us: A timestamp with an integer
number of seconds.

> I can actually produce another timestamp with the milliseconds from a
> different file...

Then you won't be able to represent it as an integer number of seconds.
What are you receiving in the data? What data type is it?

-- 
 \      ?He who allows oppression, shares the crime.? ?Erasmus Darwin, |
  `\                                     grandfather of Charles Darwin |
_o__)                                                                  |
Ben Finney



From albert at spenarnc.xs4all.nl  Tue Mar  4 21:15:14 2014
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 05 Mar 2014 02:15:14 GMT
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
Message-ID: <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>

In article <mailman.7687.1393902132.18130.python-list at python.org>,
Chris Angelico  <rosuav at gmail.com> wrote:
>On Tue, Mar 4, 2014 at 1:45 PM, Albert van der Horst
><albert at spenarnc.xs4all.nl> wrote:
>>>No, the Python built-in float type works with a subset of real numbers:
>>
>> To be more precise: a subset of the rational numbers, those with a denominator
>> that is a power of two.
>
>And no more than N bits (53 in a 64-bit float) in the numerator, and
>the denominator between the limits of the exponent. (Unless it's
>subnormal. That adds another set of small numbers.) It's a pretty
>tight set of restrictions, and yet good enough for so many purposes.
>
>But it's a far cry from "all real numbers". Even allowing for
>continued fractions adds only some more; I don't think you can
>represent surds that way.

Adding cf's adds all computable numbers in infinite precision.
However that is not even a drop in the ocean, as the computable
numbers have measure zero.
A cf object yielding its coefficients amounts to a program that generates
an infinite amount of data (in infinite time), so it is not
very surprising it can represent any computable number.

Pretty humbling really.

>
>ChrisA

Groetjes Albert
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From breamoreboy at yahoo.co.uk  Tue Mar  4 21:39:34 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 05 Mar 2014 02:39:34 +0000
Subject: Proper conversion of timestamp
In-Reply-To: <CA+FnnTzEBV2Zh-nMY7AgCbEH57uj6wVt6x5Fch-oeZmqHRTDng@mail.gmail.com>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
 <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
 <lf5l47$8q4$1@ger.gmane.org>
 <CA+FnnTzEBV2Zh-nMY7AgCbEH57uj6wVt6x5Fch-oeZmqHRTDng@mail.gmail.com>
Message-ID: <lf62os$pse$1@ger.gmane.org>

On 05/03/2014 02:13, Igor Korot wrote:
> Hi, Mark,
>
> On Tue, Mar 4, 2014 at 2:46 PM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>> On 04/03/2014 21:55, Igor Korot wrote:
>>>
>>>
>>> But this particular question is easy.
>>>
>>
>> If it's easy why can't you answer it via the docs rather than ask here?
>
> What I meant to say is: it is easy for all you people and it is
> definitely easier than
> trying to figure out how to process and display different dates.
>
> Thank you.
>

You've never once referred to anything that you've read in the docs but 
don't understand, so how can we help you?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
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From albert at spenarnc.xs4all.nl  Tue Mar  4 21:38:18 2014
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 05 Mar 2014 02:38:18 GMT
Subject: Working with the set of real numbers
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <871tz7864a.fsf@elektro.pacujo.net>
 <mailman.6861.1392319546.18130.python-list@python.org>
 <87fvnm7q1n.fsf@elektro.pacujo.net>
Message-ID: <53168e1a$0$25064$e4fe514c@dreader37.news.xs4all.nl>

In article <87fvnm7q1n.fsf at elektro.pacujo.net>,
Marko Rauhamaa  <marko at pacujo.net> wrote:
>Chris Angelico <rosuav at gmail.com>:
>
>> On Fri, Feb 14, 2014 at 1:00 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> Well, if your idealized, infinite, digital computer had ?????? bytes of RAM
>>> and ran at ?????? hertz and Python supported transfinite iteration, you
>>> could easily do reals:
>>>
>>>         for x in continuum(0, max(1, y)):
>>
>> How exactly do you iterate over a continuum, with a digital computer?
>
>How "digital" our idealized computers are is a matter for a debate.
>However, iterating over the continuum is provably "possible:"
>
>  http://en.wikipedia.org/wiki/Transfinite_induction
>
>> it would take a finite amount of time to assign to x the "next
>> number", ergo your algorithm can't guarantee to finish in finite time.
>
>My assumption was you could execute ?????? statements per second. That
>doesn't guarantee a finite finish time but would make it possible. That
>is because
>
>   ?????? * ?????? = ?????? = ?????? * 1
>
>This computer is definitely more powerful than a Turing machine, which
>only has ?????? bytes of RAM and thus can't even store an arbitrary real
>value in memory.

You're very much off the track here. A Turing machine is an abstraction
for a computer were the limitations of size are gone.
The most obvious feature of a Turing machine is an infinite tape.
A Turing machine happily calculates Ackerman functions long after
a real machine runs out of memory to represent it, with as a result
a number of ones on that tape.
But it only happens in the mathematicians mind.

>
>
>Marko
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From breamoreboy at yahoo.co.uk  Tue Mar  4 22:06:05 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 05 Mar 2014 03:06:05 +0000
Subject: 3.4rc2 and pip on windows
In-Reply-To: <lf3oi5$h9c$1@ger.gmane.org>
References: <lf0ge3$fbv$1@ger.gmane.org> <lf0h42$l88$2@ger.gmane.org>
 <lf2m8g$ouv$1@ger.gmane.org> <lf3oi5$h9c$1@ger.gmane.org>
Message-ID: <lf64ai$8it$1@ger.gmane.org>

On 04/03/2014 05:32, Terry Reedy wrote:
> On 3/3/2014 2:47 PM, Mark Lawrence wrote:
>> On 03/03/2014 00:07, Terry Reedy wrote:
>>> On 3/2/2014 6:55 PM, Mark Lawrence wrote:
>>>> Trying to install pyttsx, it doesn't strike me as very clever that, as
>>>> seen below, you get "Successfully installed pyttsx" despite the syntax
>>>> errors and you can't actually do an import.
>>>>
>>>> c:\Users\Mark\CrossCode>c:\Python34\Scripts\pip3.4.exe install pyttsx
>>>> Downloading/unpacking pyttsx
>>>>    Downloading pyttsx-1.1.tar.gz
>>>>    Running setup.py
>>>> (path:C:\Users\Mark\AppData\Local\Temp\pip_build_Mark\pyttsx\setup.py)
>>>> egg_info for package pyttsx
>>>>
>>>> Installing collected packages: pyttsx
>>>>    Running setup.py install for pyttsx
>>>>        File "C:\Python34\Lib\site-packages\pyttsx\driver.py", line 105
>>>>          except Exception, e
>>>>                          ^
>>>>      SyntaxError: invalid syntax
>
> This is from setup.py
>
>
>>>> [other syntax errors snipped]
>>>>
>>>> Successfully installed pyttsx
>
> This is from pip, saying that it successfully downloaded and installed
> the files on your disk, which it did.
>
>>> A bug it seems to me.
>
> After reading the responses on the tracker and here, the bug is in the
> total systen of interaction of multiple parts. It is not a bug for the
> part covered by the tracker.
>
>>>> Cleaning up...
>>>>
>>>> c:\Users\Mark\CrossCode>py -3.4
>>>> Python 3.4.0rc2 (v3.4.0rc2:a300712ed38c, Feb 23 2014, 10:49:04) [MSC
>>>> v.1600 32 bit (Intel)] on win32
>>>> Type "help", "copyright", "credits" or "license" for more information.
>>>>  >>> import pyttsx
>>>> Traceback (most recent call last):
>>>>    File "<stdin>", line 1, in <module>
>>>>    File "C:\Python34\lib\site-packages\pyttsx\__init__.py", line 18, in
>>>> <module>
>>>>      from engine import Engine
>>>>
>>>> I've looked at pyttsx in my 3.3 site-packages and it appears that I've
>>>> manually run 2to3.  Is this something that could be done automatically
>>>> by pip?  Your thoughts please, ladies and gentlemen.
>>>
>>> I should hope so.
>
>> FTR I raised this as http://bugs.python.org/issue20846 and it was closed
>> 11 minutes after I raised it.  I won't say anything else as I'm
>> extremely tired and irritable and might well regret it later.
>
> The issue brought to attention that the parts do not work together
> perfectly yet and stimulated some thought and some clarification on what
> needs to be done. I understand the irritation, but sleeping on it and
> letting it go is a good idea.
>

Attempted overnight sleep failed :(  Sleeping late afternoon and early 
evening GMT yesterday 04/03/2014 succeeded :)

Having raised the issue I certainly understand things much better, 
especially because of the words from Ned Deilly.

So a question springs to my mind.

How do we educate the people putting their code on pypi to correctly set 
up the relevant fields so that it can be correctly handled by any tools 
that want to download from pypi?

How does the lack of correct data and/or code on pypi add more credence 
to the impression that libraries are not ready for Python 3 when in 
actual fact they are?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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This email is free from viruses and malware because avast! Antivirus protection is active.
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From rustompmody at gmail.com  Tue Mar  4 22:36:38 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 19:36:38 -0800 (PST)
Subject: Reference
In-Reply-To: <roy-A9E76C.21091704032014@news.panix.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
Message-ID: <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>

On Wednesday, March 5, 2014 7:39:17 AM UTC+5:30, Roy Smith wrote:
>  "Rhodri James" wrote:
> > wrote:
> > > Code should look like its intent. Warping it around performance is
> > > hardly ever worthwhile.
> > That depends.  In Python, I'd agree with you; if I'm worrying about  
> > performance in Python, I'm worrying at the level of the algorithms I'm  
> > using.  In a constrained embedded C environment, which is where I spend  
> > most of my working life, writing your code so that the compiler chooses  
> > the right optimisation is critical.  Sometimes it matters a great deal to  
> > me that something like "x *= 5" compiles to a single ARM instruction, or  
> > that splitting a loop into two to avoid a conditional test will let an  
> > DSP's optimiser double the speed of a section of code.

> Yeah.  BTDT.  I've stolen the bottom three bits of a pointer for my own 
> use because I know everything is 64-bit aligned so it's all zeros 
> anyway.  I feel like there must be some organization I should be going 
> to every month that meets in a church basement and I can get up in front 
> of the room and say, "Hi, my name is Roy and I'm a C++ hacker", and have 
> everybody be supportive.

> I mostly live in the Python world these days, where I'm firmly in the 
> camp of, "Stay away from O(n^2) and don't hit the database with 
> unindexed queries, and you're probably good".  But, that's because we 
> push most of the hard work off onto C and C++ code that is written by 
> guys who worry about the bottom three bits.

> One of those really awesome tools is haproxy.  It's just amazing how 
> fast (and stable) that thing is.  It's all written in C.  Most of the if 
> statements are decorated with #pragmas telling the compiler which branch 
> is the most likely to be taken, so it can optimize better.  We need 
> people like that down in the trenches, so the rest of us can run around 
> naked in the park with flowers in our hair and not worry about the 
> bottom three bits any more.

I agree with most of the sentiment above...
Except the implication that C and C++ are equivalent

I wrote http://www.the-magus.in/Publications/chor.pdf
25 years ago criticising C *in education*.
I was half my age then and used stronger language then than I would now
Ive tried to express some pangs of conscience here
http://blog.languager.org/2013/02/c-in-education-and-software-engineering.html

However my point then as now was:
"C is dangerous to TEACH CS/programming with.
Its sweet if you KNOW what you are up to."

With C++ its horrible all the way

- C++ has pretentious abstractions that invariably leak*
  C is honest in having few abstractions

- C++ syntax is ridiculously brittle. C syntax is mostly straightforward     

- One of C's difficulties is complex binding-times: pre-process, compile, link
  load, run.  Needs work but is master-able. With C++ Ive not got the
  basics after 25 years -- order of static constructors, templates...

- I dont believe its coincidence that most of the rock-solid software
  I use has a C (not C++) under-belly -- python, linux-kernel,
  emacs, gcc, haskell, git, latex
  With apps in C++ its always catching-cook -- will it segfault me before 
  I save my file?
- Some guys with a wee bit more reputation who seem to agree with
  yours truly
  o http://article.gmane.org/gmane.comp.version-control.git/57918
  o http://harmful.cat-v.org/software/c++/rms

* ... which summarizes my objection in this thread: Python's 'is' leaks the 
machine abstraction. 'id' does it legitimately (somewhat), 
'is' does it illegitimately


From steve at pearwood.info  Tue Mar  4 22:41:13 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 03:41:13 GMT
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
Message-ID: <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>

On Wed, 05 Mar 2014 02:15:14 +0000, Albert van der Horst wrote:

> Adding cf's adds all computable numbers in infinite precision. However
> that is not even a drop in the ocean, as the computable numbers have
> measure zero.

On the other hand, it's not really clear that the non-computable numbers 
are useful or necessary for anything. They exist as mathematical 
abstractions, but they'll never be the result of any calculation or 
measurement that anyone might do.



-- 
Steven


From rustompmody at gmail.com  Tue Mar  4 22:45:04 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 19:45:04 -0800 (PST)
Subject: Origin of 'self'
In-Reply-To: <mailman.7706.1393937237.18130.python-list@python.org>
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
 <7edah9989mdjb9mrnrsh5067np0ihv1jml@4ax.com>
 <mailman.7706.1393937237.18130.python-list@python.org>
Message-ID: <49693163-cb83-4651-81c5-241fad6145d5@googlegroups.com>

On Tuesday, March 4, 2014 6:17:09 PM UTC+5:30, MRAB wrote:
> On 2014-03-04 02:09, Dennis Lee Bieber wrote:
> > On Sun, 2 Mar 2014 22:16:31 -0800 (PST), Westley Mart?nez declaimed:
> >> I understand that in an object method the first argument in the
> >> object itself, called self.  However, it doesn't have to be called
> >> self, and can be called anything.  So my question is why is it
> >> called self and not this like from C++ and Java.  It's kind of a
> >> silly question, but one that I'm curious about nevertheless.
> > It didn't want to be egotistical (as I recall, M$ VB uses "me")
> So does AppleScript.

> <OT>

> In AppleScript a script can refer to the title of a window as "title of
> window" or "window's title", and it can refer to the title of its own
> window as "title of window of me" or "me's window's title". Consistent,
> yes, but bad English.

> That's why I prefer a programming language not to be too much like a
> natural language. :-)

> </OT>

<Continue-OT>

There could be other conclusions.  Such as that English could learn
from AppleScript to not make bogus distinctions between me and my. Or
latin in which case is sufficiently explicit that word-order does not matter

<Even-more-OT>
Reminds me of
"How do we know whether smoking causes cancer or cancer causes smoking?"
</Even-more-OT>

</Continue-OT>



From python at mrabarnett.plus.com  Tue Mar  4 22:58:33 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 05 Mar 2014 03:58:33 +0000
Subject: Origin of 'self'
In-Reply-To: <49693163-cb83-4651-81c5-241fad6145d5@googlegroups.com>
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
 <7edah9989mdjb9mrnrsh5067np0ihv1jml@4ax.com>
 <mailman.7706.1393937237.18130.python-list@python.org>
 <49693163-cb83-4651-81c5-241fad6145d5@googlegroups.com>
Message-ID: <5316A0E9.90003@mrabarnett.plus.com>

On 2014-03-05 03:45, Rustom Mody wrote:
> On Tuesday, March 4, 2014 6:17:09 PM UTC+5:30, MRAB wrote:
>> On 2014-03-04 02:09, Dennis Lee Bieber wrote:
>> > On Sun, 2 Mar 2014 22:16:31 -0800 (PST), Westley Mart?nez declaimed:
>
>> >> I understand that in an object method the first argument in the
>> >> object itself, called self.  However, it doesn't have to be called
>> >> self, and can be called anything.  So my question is why is it
>> >> called self and not this like from C++ and Java.  It's kind of a
>> >> silly question, but one that I'm curious about nevertheless.
>> > It didn't want to be egotistical (as I recall, M$ VB uses "me")
>> So does AppleScript.
>
>> <OT>
>
>> In AppleScript a script can refer to the title of a window as "title of
>> window" or "window's title", and it can refer to the title of its own
>> window as "title of window of me" or "me's window's title". Consistent,
>> yes, but bad English.
>
>> That's why I prefer a programming language not to be too much like a
>> natural language. :-)
>
>> </OT>
>
> <Continue-OT>
>
> There could be other conclusions.  Such as that English could learn
> from AppleScript to not make bogus distinctions between me and my. Or
> latin in which case is sufficiently explicit that word-order does not matter
>
Latin's not that explicit: the endings aren't unique within a
declension.

> <Even-more-OT>
> Reminds me of
> "How do we know whether smoking causes cancer or cancer causes smoking?"
> </Even-more-OT>
>
> </Continue-OT>
>



From harrismh777 at gmail.com  Tue Mar  4 23:03:13 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Tue, 4 Mar 2014 20:03:13 -0800 (PST)
Subject: Geezer learns python
In-Reply-To: <bnn4dhFcq4jU2@mid.individual.net>
References: <bnn4dhFcq4jU2@mid.individual.net>
Message-ID: <04771cd8-4702-4fb6-a49d-29e265f51927@googlegroups.com>

On Tuesday, March 4, 2014 5:03:13 PM UTC-6, notbob wrote:
{snip}

hi notbob,
   Get a good book on python3 programming {Barnes and Noble, 
Amazon} and please, start with python (3).

   Great book:  & fabulous tutorial:

Summerfield, Mark. Programming in Python 3: A Complete Introduction to the Python Language.
Developer's Library. 2nd Edition. (Upper Saddle River: Addison-Wesley, 2010)

The book is 630 pages, illustrated, and explains everything with very 
clear insightful use cases, example coding, and exercises. It is also
not a bad reference, although there are better ones.  IMHO if you can
purchase just one book on python programming, this is it.

Also, don't forget that google is your friend. You will find the python
community very friendly (as compared to some groups) but folks can
be short if the questions show little or no research. There are great 
tutorials on-line for python too, and very good doc. 

Start here:  http://docs.python.org/3.3/tutorial/

Also Docs:  http://docs.python.org/3.3/#

Cheers
marcus




From ian.g.kelly at gmail.com  Tue Mar  4 23:08:58 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 4 Mar 2014 21:08:58 -0700
Subject: Reference
In-Reply-To: <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
Message-ID: <CALwzidkLua8pm_uV=BeMkBvg784y6=7kuZo30yGBAvpYuxu8Xg@mail.gmail.com>

On Tue, Mar 4, 2014 at 8:36 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> * ... which summarizes my objection in this thread: Python's 'is' leaks the
> machine abstraction. 'id' does it legitimately (somewhat),
> 'is' does it illegitimately

Well, since "if x == None" is buggy as a test for sentinel values,
that means the only legitimate non-buggy way to do it is with "if
id(x) == id(None)", which just seems gross to me.


From greg.ewing at canterbury.ac.nz  Tue Mar  4 23:06:47 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 05 Mar 2014 17:06:47 +1300
Subject: Proper conversion of timestamp
In-Reply-To: <mailman.7750.1393970120.18130.python-list@python.org>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
 <mailman.7750.1393970120.18130.python-list@python.org>
Message-ID: <bnnm6oFgcj1U1@mid.individual.net>

Igor Korot wrote:
> What I have is a timestamp which reads: 1289410678L.
> 
> Trying to convert this into the datetime object in Python using:
> 
> import datetime
> datetime.datetime.fromtimestamp( stamp )
> 
> produces the error: timestamp out of range for platform 
> localtime()/gmtime() function.

Divide the timestamp by 1000.0 to give floating point
seconds, and then use datetime.fromtimestamp().

 >>> d = datetime.datetime.fromtimestamp(1289410678 / 1000.0)
 >>> d
datetime.datetime(1970, 1, 16, 10, 10, 10, 678000)
 >>> d.strftime("%Y-%m-%d-%H:%M:%S.%f")[:-3]
'1970-01-16-10:10:10.678'

-- 
Greg


From python at mrabarnett.plus.com  Tue Mar  4 23:11:05 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 05 Mar 2014 04:11:05 +0000
Subject: Proper conversion of timestamp
In-Reply-To: <85siqxfk6s.fsf@benfinney.id.au>
References: <CA+FnnTy2zoJYzx+ExkHf8SsENppBLaQzp2zOC9WFYsLBYwK9Qg@mail.gmail.com>
 <lf5hes$ve3$1@ger.gmane.org>
 <CA+FnnTxuiNTeaTu7LEdPWvsSnbbirgXqaCS67p5HOrruQPcZ9A@mail.gmail.com>
 <5316730B.3080706@mrabarnett.plus.com>
 <CA+FnnTyvXW83OR-L78Xqx5gttv1BANiNHUGh7r5XFJkJ-bGedA@mail.gmail.com>
 <85siqxfk6s.fsf@benfinney.id.au>
Message-ID: <5316A3D9.4050305@mrabarnett.plus.com>

On 2014-03-05 02:33, Ben Finney wrote:
> Igor Korot <ikorot01 at gmail.com> writes:
>
>> On Tue, Mar 4, 2014 at 4:42 PM, MRAB <python at mrabarnett.plus.com> wrote:
>> >> But this particular question is easy.
>> >>
>> >> What I have is a timestamp which reads: 1289410678L.
>> >>
>> > That's an integer. It looks like the timestamp is a whole number of
>> > seconds, so the number of milliseconds is 0. (I make it '2010-11-10
>> > 17:37:58'.)
>>
>> Well it is this particular timestamp.
>
> Which is what you presented as ?what I have?.
>
I'd expect all of the timestamps to be the same type. That example is
an integer (a 'long' to be exact).

>> But I have a lot of files to process and some do have a timestamp with
>> the milliseconds.
>
> So, if you want help with such timestamps, you'll need to present a real
> example (or preferably several exmaples) of timestamps that need this
> handling.
>
>> Right.
>> The question is: how to get the number of milliseconds out of
>> timestamp?
>
>  From the timestamp you showed: The number of milliseconds is zero, since
> it's an integer. That datatype will *always* have zero milliseconds.
>
>> Once again: I can get the datetime object with the seconds precision
>> by dividing it on 1000. But that will produce the datetime object with
>> the seconds precision.
>
> Because that's the data you're showing us: A timestamp with an integer
> number of seconds.
>
And in Python 2, an integer divided by an integer gives an integer.

>> I can actually produce another timestamp with the milliseconds from a
>> different file...
>
> Then you won't be able to represent it as an integer number of seconds.
> What are you receiving in the data? What data type is it?
>



From python at mrabarnett.plus.com  Tue Mar  4 23:11:58 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 05 Mar 2014 04:11:58 +0000
Subject: How security holes happen
In-Reply-To: <roy-4E7DBB.20574304032014@news.panix.com>
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
Message-ID: <5316A40E.2080903@mrabarnett.plus.com>

On 2014-03-05 01:57, Roy Smith wrote:
> In article <mailman.7777.1393980007.18130.python-list at python.org>,
>   Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>
>> On Wed, 05 Mar 2014 00:48:40 +0200, Marko Rauhamaa <marko at pacujo.net>
>> declaimed the following:
>>
>> >Ethan Furman <ethan at stoneleaf.us>:
>> >
>> >> Okay, that looks totally cool. Maybe I'll finally get a handle on
>> >> LISP! :)
>> >
>> >Lisp is conceptually simpler than Python, but awe-inspiring. One day, it
>> >will overtake Python, I believe.
>
> I first played with Lisp in 1976.  The only time I ever used it for
> anything serious was an A/I course I took in the mid 80's.  At the end
> of the semester, I was just starting to write things in Lisp (as opposed
> to writing C transliterated to Lisp syntax and keywords).
>
>>  It's already had 54 years to become a major language...
>>
>>  Instead it has schismed into Common Lisp and Scheme (and a few other
>> dialects)
>
> Python has had 23 years to become a major language...
>
> Instead it has schismed into Python 2.x and Python 3.x.
>
Into how many versions did Lisp split in its first 23 years? :-)

> [holding hands over ears to avoid the howls of derision, while ducking
> and running]
>



From rustompmody at gmail.com  Tue Mar  4 23:15:19 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 20:15:19 -0800 (PST)
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>

On Wednesday, March 5, 2014 9:11:13 AM UTC+5:30, Steven D'Aprano wrote:
> On Wed, 05 Mar 2014 02:15:14 +0000, Albert van der Horst wrote:

> > Adding cf's adds all computable numbers in infinite precision. However
> > that is not even a drop in the ocean, as the computable numbers have
> > measure zero.

> On the other hand, it's not really clear that the non-computable numbers 
> are useful or necessary for anything. They exist as mathematical 
> abstractions, but they'll never be the result of any calculation or 
> measurement that anyone might do.

There are even more extreme versions of this amounting to roughly this view:
"Any infinity supposedly 'larger' than the natural numbers is a nonsensical notion."

See eg
http://en.wikipedia.org/wiki/Controversy_over_Cantor%27s_theory

and Weyl/Polya bet (pg 10 of http://research.microsoft.com/en-us/um/people/gurevich/Opera/123.pdf )

I cannot find the exact quote so from memory Weyl says something to this effect:

Cantor's diagonalization PROOF is not in question.
Its CONCLUSION very much is.
The classical/platonic mathematician (subject to wooly thinking) concludes that 
the real numbers are a superset of the integers

The constructvist mathematician (who supposedly thinks clearly) only concludes
the obvious, viz that real numbers cannot be enumerated

To go from 'cannot be enumerated' to 'is a proper superset of' requires the 
assumption of 'completed infinities' and that is not math but theology


From gheskett at wdtv.com  Tue Mar  4 23:27:13 2014
From: gheskett at wdtv.com (Gene Heskett)
Date: Tue, 4 Mar 2014 23:27:13 -0500
Subject: How security holes happen
In-Reply-To: <izuRu.12475$wf3.1354@fx10.am4>
References: <lf22t1$sgh$1@ger.gmane.org>
 <mailman.7670.1393885170.18130.python-list@python.org>
 <izuRu.12475$wf3.1354@fx10.am4>
Message-ID: <201403042327.14066.gheskett@wdtv.com>

On Tuesday 04 March 2014 23:17:40 Andrew Cooper did opine:

> On 03/03/2014 22:19, Cameron Simpson wrote:
> > On 03Mar2014 09:17, Neal Becker <ndbecker2 at gmail.com> wrote:
> >>  Charles R Harris <charlesr.harris at gmail.com> Wrote in message:
> >> Imo the lesson here is never write in low level c. Use modern
> >> 
> >>  languages with well designed exception handling.
> > 
> > What, and rely on someone else's low level C?
> 
> Why is C the lowest denominator?
> 
> Even with correctly written C and assembly, how can you be sure that
> your processor is executing the SYSRET instruction safely?
> (CVE-2012-0217 for anyone interested)
> 
If you do not have the system tools to determine that, the system is 
seriously incomplete.  Change os's, its that simple when you are down to 
the bare metal.

If I wanted to determine that was correct on the TRS-80 Color Computer 3 in 
the basement, running nitros9 right now, I would put 3 calls to F$RegDump 
in the assembly code, one in the caller as the last thing done before the 
call, one in the subroutine immediately in front of the return, and one as 
the first operation done when the return register image has been pulled 
from the stack.

> ~Andrew


Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

NOTICE: Will pay 100 USD for an HP-4815A defective but
complete probe assembly.



From roy at panix.com  Tue Mar  4 23:25:37 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 04 Mar 2014 23:25:37 -0500
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
Message-ID: <roy-38F1BC.23253704032014@news.panix.com>

In article <c39d5b44-6c7b-40d1-bbb5-791a36af6857 at googlegroups.com>,
 Rustom Mody <rustompmody at gmail.com> wrote:

> I cannot find the exact quote so from memory Weyl says something to this 
> effect:
> 
> Cantor's diagonalization PROOF is not in question.
> Its CONCLUSION very much is.
> The classical/platonic mathematician (subject to wooly thinking) concludes 
> that 
> the real numbers are a superset of the integers
> 
> The constructvist mathematician (who supposedly thinks clearly) only 
> concludes
> the obvious, viz that real numbers cannot be enumerated
> 
> To go from 'cannot be enumerated' to 'is a proper superset of' requires the 
> assumption of 'completed infinities' and that is not math but theology

I stopped paying attention to mathematicians when they tried to convince 
me that the sum of all natural numbers is -1/12.  Sure, you can 
manipulate the symbols in a way which is consistent with some set of 
rules that we believe govern the legal manipulation of symbols, but it 
just plain doesn't make sense.


From ben+python at benfinney.id.au  Tue Mar  4 23:32:16 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 05 Mar 2014 15:32:16 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
Message-ID: <85ob1lfepb.fsf@benfinney.id.au>

Rustom Mody <rustompmody at gmail.com> writes:

> * ... which summarizes my objection in this thread:

Your long post references many things. Which is the ?which? to which you
refer? What is it you're referring to that summarises your position?

> Python's 'is' leaks the machine abstraction.

No, it does not. The ?is? operator compares object identity, which is
itself an abstraction. What is leaking?

Note that the ?location of the object in memory? is not a guarantee made
by either Python's object identity nor the ?id? function. There's no
need to treat ?object location in memory? as equal to ?object identity?,
and code which makes that assumption is buggy. The documentation doesn't
promise they will be the same.

So, the fact that some Python implementations happen to present
?id(foo)? values that coincide with a representation of memory location,
does not constitute a leaky abstraction: there is no need for any Python
programmer to care about what the memory location is. So if that's the
basis of your objection, I don't consider that objection to be
legitimate.

> 'id' does it legitimately (somewhat), 'is' does it illegitimately

What would, in your view, be a legitimate way for Python to present
object identity to the programmer? How would it differ substantially
from Python's existing abstraction of object identity?

-- 
 \          ?That's all very good in practice, but how does it work in |
  `\                                             *theory*?? ?anonymous |
_o__)                                                                  |
Ben Finney



From rustompmody at gmail.com  Tue Mar  4 23:31:52 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 20:31:52 -0800 (PST)
Subject: Reference
In-Reply-To: <mailman.7787.1393992587.18130.python-list@python.org>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <mailman.7787.1393992587.18130.python-list@python.org>
Message-ID: <16c6d0af-924c-4b44-9d0a-614ccde61720@googlegroups.com>

On Wednesday, March 5, 2014 9:38:58 AM UTC+5:30, Ian wrote:
> On Tue, Mar 4, 2014 at 8:36 PM, Rustom Mody wrote:
> > * ... which summarizes my objection in this thread: Python's 'is' leaks the
> > machine abstraction. 'id' does it legitimately (somewhat),
> > 'is' does it illegitimately

> Well, since "if x == None" is buggy as a test for sentinel values,
> that means the only legitimate non-buggy way to do it is with "if
> id(x) == id(None)", which just seems gross to me.

Ha Ha! -- Fully agreed!
One should not need to leak the machine abstraction for something as basic
as None testing

As I said earlier my current preference which is least disruptive is to have
as builtin

def isNone(x): return x is None

which should obviate most (basic) uses of is


From ben+python at benfinney.id.au  Tue Mar  4 23:37:44 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 05 Mar 2014 15:37:44 +1100
Subject: Working with the set of real numbers
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
Message-ID: <85k3c9feg7.fsf@benfinney.id.au>

Roy Smith <roy at panix.com> writes:

> I stopped paying attention to mathematicians when they tried to convince 
> me that the sum of all natural numbers is -1/12.

I stopped paying attention to a particular person when they said ?I
stopped paying attention to an entire field of study because one
position expressed by some practicioners was disagreeable to me?.

Would you think ?I stopped listening to logicians when some of them
expressed Zeno's paradox of the impossibility of motion? to be a good
justification for ignoring the entire field of logic?

Rather, a more honest response is to say why that position is incorrect,
and not dismiss the entire field of study merely for a disagreement with
that position.

-- 
 \      ?Life does not cease to be funny when people die any more than |
  `\  it ceases to be serious when people laugh.? ?George Bernard Shaw |
_o__)                                                                  |
Ben Finney



From rustompmody at gmail.com  Tue Mar  4 23:47:36 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 20:47:36 -0800 (PST)
Subject: Reference
In-Reply-To: <mailman.7791.1393993951.18130.python-list@python.org>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <mailman.7791.1393993951.18130.python-list@python.org>
Message-ID: <79068c6c-b0bc-4917-af6e-80f497a0474c@googlegroups.com>

On Wednesday, March 5, 2014 10:02:16 AM UTC+5:30, Ben Finney wrote:
> Rustom Mody writes:

> > * ... which summarizes my objection in this thread:

> Your long post references many things. Which is the "which" to which you
> refer? What is it you're referring to that summarises your position?

Text : C++ has pretentious abstractions that invariably leak* 

Footnote: * ... which summarizes my objection in this thread: Python's 'is' 
leaks the machine abstraction. 'id' does it legitimately (somewhat),
'is' does it illegitimately 

Not sure whats not clear: "is" in python leaks machine representations 
into the otherwise clean HLL abstraction in python like <dozens of things> in C++


From rustompmody at gmail.com  Tue Mar  4 23:57:09 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 20:57:09 -0800 (PST)
Subject: Working with the set of real numbers
In-Reply-To: <mailman.7792.1393994283.18130.python-list@python.org>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <mailman.7792.1393994283.18130.python-list@python.org>
Message-ID: <deb5b4f8-9453-4ed3-84fe-571fd1796d51@googlegroups.com>

On Wednesday, March 5, 2014 10:07:44 AM UTC+5:30, Ben Finney wrote:
> Roy Smith writes:

> > I stopped paying attention to mathematicians when they tried to convince 
> > me that the sum of all natural numbers is -1/12.

> I stopped paying attention to a particular person when they said "I
> stopped paying attention to an entire field of study because one
> position expressed by some practicioners was disagreeable to me".

In general this is a correct response
In this particular case (apart from Roy speaking tongue-in-cheek)
it (Roy's viewpoint) is more appropriate and central to our field than you
perhaps realize:

Nonsensical results believed in by a small minority (Cantor's time)
became full scale war between platonists (Hilbert) and constructivists
(Brouwer) a generation later.

G?del staunchly in Hilbert camp made his incompleteness theorem to rebut the
constructivists

Turing unable to disagree with G?del's result but disagreeing with platonic
philosophy made his 'machine'. The negative result that he did not like but
had to admit was uncomputability/undecidability. However he trumped G?del in
making a 'universal' machine

And so we are here :-)



From steve at pearwood.info  Wed Mar  5 00:06:37 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 05:06:37 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
Message-ID: <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>

On Tue, 04 Mar 2014 19:36:38 -0800, Rustom Mody wrote:

> Python's 'is' leaks
> the machine abstraction. 'id' does it legitimately (somewhat), 'is' does
> it illegitimately

and then later in another post:

> "is" in python leaks machine representations
> into the otherwise clean HLL abstraction in python


Rather than respond with incredulity and declare that you have no idea 
what you are talking about, I'll give you the benefit of the doubt, and 
accept the possibility that I am wrong, or possibly misunderstanding you.

Can you explain what machine representations are leaked into Python by 
the is operator?

Do you see this as an accident of implementation, a bug that might be 
fixed, or a misfeature that was deliberately designed?

Can you elaborate on why id() is legitimate and "is" is not?


-- 
Steven


From roy at panix.com  Wed Mar  5 00:29:43 2014
From: roy at panix.com (Roy Smith)
Date: Wed, 05 Mar 2014 00:29:43 -0500
Subject: Working with the set of real numbers
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <mailman.7792.1393994283.18130.python-list@python.org>
Message-ID: <roy-778104.00294305032014@news.panix.com>

In article <mailman.7792.1393994283.18130.python-list at python.org>,
 Ben Finney <ben+python at benfinney.id.au> wrote:

> Roy Smith <roy at panix.com> writes:
> 
> > I stopped paying attention to mathematicians when they tried to convince 
> > me that the sum of all natural numbers is -1/12.
> 
> I stopped paying attention to a particular person when they said ???I
> stopped paying attention to an entire field of study because one
> position expressed by some practicioners was disagreeable to me???.
> 
> Would you think ???I stopped listening to logicians when some of them
> expressed Zeno's paradox of the impossibility of motion??? to be a good
> justification for ignoring the entire field of logic?
> 
> Rather, a more honest response is to say why that position is incorrect,
> and not dismiss the entire field of study merely for a disagreement with
> that position.

I *was* partly joking (but only partly).

Still, there's lots of stuff mathematicians do which I don't understand.  
I cannot understand, for example, Andrew's Wiles's proof of Fermat's 
Last Theorm.  I can't even get past the first few paragraphs of the 
Wikipedia article.  But, that doesn't sour me on the proof.  I can 
accept that there are things I don't understand.  I don't know how to 
speak Chinese.  I don't know how to paint a flower.  I don't know how to 
run a mile in 4 minutes.  But I accept that there are people who do know 
how to do those things.

I can watch a friend pick up a piece of paper, a brush, and some 
watercolors and 5 minutes later, she's got a painting of a flower.  I 
watched her hands hold the brush and move it over the paper.  There's 
nothing mystical about what she did.  Her hands made no motions which 
are fundamentally impossible for my hands to make, yet I know that my 
attempt at reproducing her work would not result in a painting of a 
flower.

But, as I watch the -1/12 proof unfold, I don't get the same feeling.  I 
understand every step.  I wouldn't have thought to manipulate the 
symbols that way, but once I've seen it done, I can reproduce the steps 
myself.  It's all completely understandable.  The only problem is, it 
results in a conclusion which makes no sense.  I can *prove* that it 
makes no sense, by manipulating the symbols in different ways.  The sum 
of any two positive numbers must be positive.  I can group them and add 
them up any way I want and that's still true.

But, here I've got some guy telling me it's not true.  If you just slide 
this over that way, and add these parts up this way, it's -1/12.  That 
does not compute.  But it doesn't not compute in the sense of, "that's 
so complicated, I have no idea what you did", but in the sense of "thats 
so simple, I know exactly what you did, and it's bullshit" :-)


From rustompmody at gmail.com  Wed Mar  5 00:47:21 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 21:47:21 -0800 (PST)
Subject: Reference
In-Reply-To: <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>

On Wednesday, March 5, 2014 10:36:37 AM UTC+5:30, Steven D'Aprano wrote:
> On Tue, 04 Mar 2014 19:36:38 -0800, Rustom Mody wrote:

> > Python's 'is' leaks
> > the machine abstraction. 'id' does it legitimately (somewhat), 'is' does
> > it illegitimately

> and then later in another post:

> > "is" in python leaks machine representations
> > into the otherwise clean HLL abstraction in python

> Rather than respond with incredulity and declare that you have no idea 
> what you are talking about, I'll give you the benefit of the doubt, and 
> accept the possibility that I am wrong, or possibly misunderstanding you.

Umm...
I guess my language was sloppy (a bit)
A machine is ultimately also an abstraction --
What is firmware/microcode? Is it a virtual machine? etc
Lets leave that however and just take 'machine' as a given.

Using machines as given, we build reprs for our (programmer's) data structures

So data structures are abstractions that have two 'faces' -- 
the machine-facing and the programmer-facing

For clarity of expression (and where you perhaps found me sloppy?? not sure...)
its best to call the machine-face 'a representation' and the programmer-face
'an abstraction'

Clearly this is a programmer-biased viewpoint. A hardware engineer would see
things differently. As would the user of the app the programmer programs.

Which is why to use the locution "is" without appropriate framing is philosopical
is a pretension to a 'God's-eye-view'.
If you are privy to such a viewpoint I'd be interested to know
But for the rest of us who are not, its good to remember there are only
perspectives no absolute truth.

That python is a hll means that machine reprs are intended to be abstracted
away. 'is' fails to do that -- proof of that being the discrepancy between
is and ==

> Can you explain what machine representations are leaked into Python by 
> the is operator?

> Do you see this as an accident of implementation, a bug that might be 
> fixed, or a misfeature that was deliberately designed?

> Can you elaborate on why id() is legitimate and "is" is not?

Let me talk of Lisp which is IMHO more philosophically sane.
Lisp has eq eql equal and a few type-specific others such as = for numbers
string-= for strings etc

eq is roughly python's 'is'
equal is roughl python's ==
The type-specific ones error out rather than returning false for out-of-bounds types.

So much for the technology

Now to the philosophy behind it:
Decide the viewpoint  -- choose the appropriate equivence predicate
No claim even remotely to having a clue to metaphysical being that python's 'is' implies


From wuwei23 at gmail.com  Wed Mar  5 01:01:04 2014
From: wuwei23 at gmail.com (alex23)
Date: Wed, 05 Mar 2014 16:01:04 +1000
Subject: Reference
In-Reply-To: <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
Message-ID: <lf6ej2$hum$1@dont-email.me>

On 5/03/2014 3:47 PM, Rustom Mody wrote:
> That python is a hll means that machine reprs are intended to be abstracted
> away. 'is' fails to do that -- proof of that being the discrepancy between
> is and ==

The "discrepancy" is because _they're fundamentally different_:

     >>> a = b = [1,2]
     >>> c = [1,2]
     >>> a is b
     True
     >>> a is c
     False
     >>> a == b
     True
     >>> a == c
     True

`is` is used to determine if two names refer to the same object.
`==` is used to determine if they're equivalent in value.

Both have their uses.


From rustompmody at gmail.com  Wed Mar  5 01:03:36 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 22:03:36 -0800 (PST)
Subject: Reference
In-Reply-To: <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>

On Wednesday, March 5, 2014 10:36:37 AM UTC+5:30, Steven D'Aprano wrote:
> On Tue, 04 Mar 2014 19:36:38 -0800, Rustom Mody wrote:

> > Python's 'is' leaks
> > the machine abstraction. 'id' does it legitimately (somewhat), 'is' does
> > it illegitimately


> Can you elaborate on why id() is legitimate and "is" is not?

Mostly a question of more or less infelicitous English leading to philosophical
nonsense. [And note I put a 'somewhat']

I can say "'id' is just 'machine-id' is just address at some low level"

Its uglier to say "Is is machine-is"

And before you bring it up, "Jython's id is not machine-id" is putting
the cart before the horse.

"Jython is an imitation of Cpython and does a good job but not quite as
in the case of 'id'"

is the right order (IMHO)


From rustompmody at gmail.com  Wed Mar  5 01:10:12 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 22:10:12 -0800 (PST)
Subject: Reference
In-Reply-To: <lf6ej2$hum$1@dont-email.me>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <lf6ej2$hum$1@dont-email.me>
Message-ID: <f82e009f-3701-44ec-85a5-6680529f65b3@googlegroups.com>

On Wednesday, March 5, 2014 11:31:04 AM UTC+5:30, alex23 wrote:
> On 5/03/2014 3:47 PM, Rustom Mody wrote:
> > That python is a hll means that machine reprs are intended to be abstracted
> > away. 'is' fails to do that -- proof of that being the discrepancy between
> > is and ==

> The "discrepancy" is because _they're fundamentally different_:

Yeah I know :D


> Both have their uses.

Yes -- see my lisp example above

>      >>> a = b = [1,2]
>      >>> c = [1,2]
>      >>> a is b
>      True
>      >>> a is c
>      False
>      >>> a == b
>      True
>      >>> a == c
>      True

> `==` is used to determine if they're equivalent in value.

Right

> `is` is used to determine if two names refer to the same object.


'Same' is 'is' in a different guise and is what I object to.

A python programmer who needs/wants to think of same/is in this sense
should probably be using C or assembly

In the exceptional circumstances when 'low-level-machine-equivalence-relation'
is desired, a name carrying some of those connotations would be ok


From ben+python at benfinney.id.au  Wed Mar  5 01:20:46 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 05 Mar 2014 17:20:46 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
Message-ID: <85fvmxf9oh.fsf@benfinney.id.au>

Rustom Mody <rustompmody at gmail.com> writes:

> That python is a hll means that machine reprs are intended to be abstracted
> away. 'is' fails to do that -- proof of that being the discrepancy between
> is and ==

That's your proof? That is a non sequitur. Those two operators are
*designed to be* different, to compare different things.

How does the difference between ?==? versus ?is?, which are designed and
documented to have different behaviour, lead to your assertion of a
?leaky abstraction??

You have yet to respond to this question asked several times:

> > Can you explain what machine representations are leaked into Python
> > by the is operator?

So, what machine represenatation is leaked?

I'll re-iterate that ?memory location of the object? isn't a valid
response. There is no necessary relation between the memory location of
the object referenced by ?foo? and the return value of ?id(foo)?. The
latter is useable with utter ignorance of the concept of memory
location, so it is not a leaky abstraction.

Note that for an abstraction to be leaky, the programmer must *be
required* to have an understanding of what lies beneath the abstraction.
If the values that the programmer deals with can be dealt with entirely
at the level of the abstraction, and no knowledge of what's under the
hood is needed, then the abstraction does not leak.

> No claim even remotely to having a clue to metaphysical being that
> python's 'is' implies

Yes, exactly. You have no need to know what is under the hood: it is the
object's identity, which is simply a property which is unique to that
object among all other concurrently-existing objects.

The value returned by ?id(foo)? and compared by ?is? means nothing else
other than the abstraction of ?object identity?. The value has to be
*something*, so it may resemble other things ? such as the object's
memory location, or not ? but that resemblance is not promised by
anything, and is irrelevant to the user of the abstraction.

-- 
 \       ?As far as the laws of mathematics refer to reality, they are |
  `\    not certain, and as far as they are certain, they do not refer |
_o__)                              to reality.? ?Albert Einstein, 1983 |
Ben Finney



From marko at pacujo.net  Wed Mar  5 01:23:21 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 08:23:21 +0200
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
Message-ID: <8761ntp3ja.fsf@elektro.pacujo.net>

Rustom Mody <rustompmody at gmail.com>:

> * ... which summarizes my objection in this thread: Python's 'is'
> leaks the machine abstraction. 'id' does it legitimately (somewhat),
> 'is' does it illegitimately

I agree that the Python data model can be exceedingly challenging to a
beginner. However, I wouldn't throw the baby away with the bathwater,
but look for ingenious ways to teach it.

The Spanish say, "Mal de muchos, consuelo de tontos." Python is hardly
alone in this mess. For example, Java's '==' operator corresponds to
Python's "is". Nobody would consider throwing Java's "==" away. Instead,
we are offered esoteric rules like:

   If the value p being boxed is true, false, a byte, a char in the
   range \u0000 to \u007f, or an int or short number between -128 and
   127, then let r1 and r2 be the results of any two boxing conversions
   of p. It is always the case that r1 == r2. <URL: http://docs.ora
   cle.com/javase/specs/jls/se5.0/html/conversions.html#5.1.7>

For Python's "==", Java offers the "equals()" method. So is it wrong in
Java to check:

   if (list.equals(null)) {

The spec says:

   For any non-null reference value x, x.equals(null) should return
   false. <URL: http://docs.oracle.com/javase/7/docs/api/java/lang/O
   bject.html#equals%28java.lang.Object%29>

So it *should* work, but why would you avoid the more natural test:

   if (list == null) {


Similarly, in Python:

   if the_list == None:

*should* work (even if there's no such stipulation in Python's reference
 material), but why wouldn't you use the more natural:

   if the_list is None:


Marko


From ben+python at benfinney.id.au  Wed Mar  5 01:22:31 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 05 Mar 2014 17:22:31 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <lf6ej2$hum$1@dont-email.me>
 <f82e009f-3701-44ec-85a5-6680529f65b3@googlegroups.com>
Message-ID: <85bnxlf9lk.fsf@benfinney.id.au>

Rustom Mody <rustompmody at gmail.com> writes:

> A python programmer who needs/wants to think of same/is in this sense
> should probably be using C or assembly

Please back up that bald assertion. How does the usefulness of the
?object identity? abstraction oblige the programmer to not use Python?

-- 
 \      ?Software patents provide one more means of controlling access |
  `\      to information. They are the tool of choice for the internet |
_o__)                                     highwayman.? ?Anthony Taylor |
Ben Finney



From wuwei23 at gmail.com  Wed Mar  5 01:28:53 2014
From: wuwei23 at gmail.com (alex23)
Date: Wed, 05 Mar 2014 16:28:53 +1000
Subject: Reference
In-Reply-To: <f82e009f-3701-44ec-85a5-6680529f65b3@googlegroups.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <lf6ej2$hum$1@dont-email.me>
 <f82e009f-3701-44ec-85a5-6680529f65b3@googlegroups.com>
Message-ID: <lf6g75$pao$1@dont-email.me>

On 5/03/2014 4:10 PM, Rustom Mody wrote:
> A python programmer who needs/wants to think of same/is in this sense
> should probably be using C or assembly

Any programmer who is obsessing about some idea of philosophical purity 
should probably not be using Python.



From ben+python at benfinney.id.au  Wed Mar  5 01:26:25 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 05 Mar 2014 17:26:25 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
Message-ID: <857g89f9f2.fsf@benfinney.id.au>

Rustom Mody <rustompmody at gmail.com> writes:

> I can say "'id' is just 'machine-id' is just address at some low
> level"

You could say that, but it's wrong. The only thing promised by ?object
identity? is that each object has it, and that it is different from the
identity of every other object concurrently existing.

?Machine id? is not entailed within that at all.

> And before you bring it up, "Jython's id is not machine-id" is putting
> the cart before the horse.

You have a false idea of what Python's object identity means, and it has
warped your understanding of what implementations do.

> "Jython is an imitation of Cpython and does a good job but not quite as
> in the case of 'id'"

Wrong. Jython and CPython both adhere to the guarantees of object
identity. Both implementations follow the language reference, and
neither implementation does object identity better or worse than the
other.

-- 
 \       ?Science shows that belief in God is not only obsolete. It is |
  `\                        also incoherent.? ?Victor J. Stenger, 2001 |
_o__)                                                                  |
Ben Finney



From rosuav at gmail.com  Wed Mar  5 01:32:57 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 17:32:57 +1100
Subject: Reference
In-Reply-To: <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
Message-ID: <CAPTjJmo7qWKGFmXuMPjggeRyrufu749EmVEB5vzsSrryoKdx+Q@mail.gmail.com>

On Wed, Mar 5, 2014 at 5:03 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> I can say "'id' is just 'machine-id' is just address at some low level"

And I can say that "id" returns a list of digits, but that doesn't
make either statement true.

The id() function returns a number which (a) never changes for any
given object, and (b) will never be the same for any two
concurrently-existing objects. It's a proxy for object identity.
That's all.

ChrisA


From rustompmody at gmail.com  Wed Mar  5 01:33:58 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 4 Mar 2014 22:33:58 -0800 (PST)
Subject: Reference
In-Reply-To: <8761ntp3ja.fsf@elektro.pacujo.net>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <8761ntp3ja.fsf@elektro.pacujo.net>
Message-ID: <89e7d1ac-af88-4781-b23d-b64e571e811b@googlegroups.com>

On Wednesday, March 5, 2014 11:53:21 AM UTC+5:30, Marko Rauhamaa wrote:
> Rustom Mody :

> > * ... which summarizes my objection in this thread: Python's 'is'
> > leaks the machine abstraction. 'id' does it legitimately (somewhat),
> > 'is' does it illegitimately

> I agree that the Python data model can be exceedingly challenging to a
> beginner. However, I wouldn't throw the baby away with the bathwater,
> but look for ingenious ways to teach it.

I'm curious how you understand my position on this
You hear me as saying 'is' should go??

No I am not saying that

All I am saying is that 'is' should have (be!) a name that is not
philosophically grandiloquent bullshit but rather a name that more
accurately conveys 'machine-representation-equivalence'


From marko at pacujo.net  Wed Mar  5 01:37:42 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 08:37:42 +0200
Subject: How security holes happen
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
Message-ID: <871tyhp2vd.fsf@elektro.pacujo.net>

MRAB <python at mrabarnett.plus.com>:

> Into how many versions did Lisp split in its first 23 years? :-)

I'm partial to Scheme, but I'll take any version.

If you had tried Python 30 years ago, you'd give it up for any serious
work because it would be so slow and consume so much memory. C++ virtual
functions used to be avoided because of performance reasons. These are
truly amazing times for computing: Java, C#, Python etc are now
mainstream, and advanced programming concepts like closures are
available to and expected from run-of-the-mill code pushers.

Java programmers were afflicted by XML and didn't know of anything
better. They are now being exposed to Clojure.

Python programmers are starting to see glimpses of a better world with
ast.literal_eval().

So we are getting there. Give it a few more decades.


Marko


From ben+python at benfinney.id.au  Wed Mar  5 01:40:40 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 05 Mar 2014 17:40:40 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <8761ntp3ja.fsf@elektro.pacujo.net>
 <89e7d1ac-af88-4781-b23d-b64e571e811b@googlegroups.com>
Message-ID: <8538ixf8rb.fsf@benfinney.id.au>

Rustom Mody <rustompmody at gmail.com> writes:

> All I am saying is that 'is' should have (be!) a name that is not
> philosophically grandiloquent bullshit but rather a name that more
> accurately conveys 'machine-representation-equivalence'

You haven't made either case.

How is the simple abstraction of object identity characterised as
?philosophically grandiloquent bullshit??

Why should we discard the useful abstraction of object identity as it
currently is in Python, for some different concept that you prefer
(?machine representation equivalence?, whatever that's supposed to be ?
I don't care right now, only that you want something different from what
is now) and have not justified why?

-- 
 \      ?The opposite of a correct statement is a false statement. But |
  `\     the opposite of a profound truth may well be another profound |
_o__)                                              truth.? ?Niels Bohr |
Ben Finney



From harrismh777 at gmail.com  Wed Mar  5 02:09:43 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Tue, 4 Mar 2014 23:09:43 -0800 (PST)
Subject: python decimal library dmath.py v0.3 released
In-Reply-To: <4c40a0a4-e8ee-422a-a227-4a1a0597bb81@googlegroups.com>
References: <55fc232e-f1a5-4c28-8fc0-06b3e3c63a68@googlegroups.com>
 <4c40a0a4-e8ee-422a-a227-4a1a0597bb81@googlegroups.com>
Message-ID: <95331e0f-2775-4927-b3d2-ca6129febc9b@googlegroups.com>

On Monday, March 3, 2014 7:46:38 PM UTC-6, Mark H. Harris wrote:
> On Monday, March 3, 2014 5:34:30 AM UTC-6, Mark H. Harris wrote:
> 
> > https://code.google.com/p/pythondecimallibrary/
> 
>    https://pypi.python.org/pypi/pdeclib/0.3

Greetings, just a minor update here for version testing and portability.
I have tested pdeclib.py | pilib.py on the following distributions:

Py2.5     [ not supported, problems with "with" and localcontext ]
Py2.6.1  [ runs correctly as written ]
Py2.7.2  [ runs correctly as written ]
Py2.7.6  [ runs correctly as written ]
Py3.2.0  [ runs correctly as written ]
Py3.3.4  [ runs very fast ]

Py2.7.2 was interesting for me to verify, because that is the version
that is currently supported by the QPython people, for the Android
platform. I now have pdeclib module loaded on my phone running
quite well, Samsung Galaxy SII Android 4.1.2 QPython 0.9.7.2 (Py2.7.2), 
although not as speedy as 3.3, it imports & runs without errors so far.

If you put pdeclib on your Android tablet|phone, you may run the script
from your personal directory, of course, or you may place it in the
python2.7 lib/site-packages folder and it will be on the PYTHONPATH
regardless of which directory you open python2.7.2 over.

marcus


From christoff.kok at ex-mente.co.za  Wed Mar  5 02:10:33 2014
From: christoff.kok at ex-mente.co.za (Christoff Kok)
Date: Tue, 4 Mar 2014 23:10:33 -0800 (PST)
Subject: Struggling to create an extension wrapping a 3rd party dll
Message-ID: <4f813ff8-d0c8-4370-b669-5484f3dcd467@googlegroups.com>

Hi,

We are trying to wrap a 3rd party dll (written in C) to access it through python.
The dll has a .lib .c and a .h file with it. We are accessing the dll through the .c file.

Outisde of the extension (running as a console application), the code works without an issue. without the 3rd party dll, the python extension works without an issue. The issue comes in when trying combine the third party dll with the python extension.

Here is the distutil installation script

################ Setup.py ################################

from distutils.core import setup, Extension

chemAppPython_mod = Extension('chemAppPython', sources = ['chemAppPython.c', 'cacint.c'], libraries=['ca_vc_opt_e'], depends = ['cacint.h'])

setup(name = "chemAppPython",
    version = "1.0",
    description = "The ChemnApp Python module",
    ext_modules = [chemAppPython_mod],
	data_files = [('',['ca_vc_e.dll'])]
)

##########################################################

* ca_vc_opt_e.lib and ca_vc_e.dll is the library containing the third party methods we want to access.

* cacint.h and cacint.c is the files acting as an interface to the ca_vc_opt_e.lib and ca_vc_e.dll.
* chemAppPython.c is file containing the code wrapping the calls to the cacint.c (and in effect, the third party dll)

The errors we are receiving are:
C:\Python33\source\Python-3.3.4\ChemAppPython>setup.py install
running install
running build
running build_ext
building 'chemAppPython' extension
creating build
creating build\temp.win-amd64-3.3
creating build\temp.win-amd64-3.3\Release
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -IC:\Python33\include -IC:\Python33\include /TcchemAppPython.c /Fobuild\temp.win-amd64-3.3\Release\chemAppPython.obj
chemAppPython.c
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -IC:\Python33\include -IC:\Python33\include /Tccacint.c /Fobuild\temp.win-amd64-3.3\Release\cacint.obj
cacint.c
cacint.c(357) : warning C4267: 'function' : conversion from 'size_t' to 'long', possible loss of data
cacint.c(390) : warning C4267: 'function' : conversion from 'size_t' to 'long', possible loss of data
.
.
. (some more of the same warning message for different functions.)
.
cacint.c(619) : warning C4996: 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
.
.
. 
. (some more of the same warning message at different positions in code.)
.
creating build\lib.win-amd64-3.3
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\link.exe /DLL /nologo /INCREMENTAL:NO /LIBPATH:C:\Python33\libs /LIBPATH:C:\Python33\PCbuild\amd64 ca_vc_opt_e.lib /EXPORT:PyInit_chemAppPython build\temp.win-amd64-3.3\Release\chemAppPython.obj build\temp.win-amd64-3.3\Rele
chemAppPython.obj : warning LNK4197: export 'PyInit_chemAppPython' specified multiple times; using first specification
   Creating library build\temp.win-amd64-3.3\Release\chemAppPython.lib and object build\temp.win-amd64-3.3\Release\chemAppPython.exp
cacint.obj : error LNK2019: unresolved external symbol TQINI referenced in function tqini
cacint.obj : error LNK2019: unresolved external symbol TQOPEN referenced in function tqopen
.
.
. (a lot more of them, for different methods. Again, it builds and runs fine in the console app host application.)
.
build\lib.win-amd64-3.3\chemAppPython.pyd : fatal error LNK1120: 74 unresolved externals
error: command '"C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\link.exe"' failed with exit status 1120


Help would really be appreciated.


From bouncingcats at gmail.com  Wed Mar  5 02:52:31 2014
From: bouncingcats at gmail.com (David)
Date: Wed, 5 Mar 2014 18:52:31 +1100
Subject: Geezer learns python
In-Reply-To: <bnn4dhFcq4jU2@mid.individual.net>
References: <bnn4dhFcq4jU2@mid.individual.net>
Message-ID: <CAMPXz=oaStML2FyVM1kKV1_+Y+TpaABzQ5zQqfmrnxdT4RXJgQ@mail.gmail.com>

On 5 March 2014 10:03, notbob <notbob at nothome.com> wrote:
>
> I'm trying to learn python.  I'm doing it via Zed Shaw's Learn Python
> the Hard Way.  Sure enough, 16 lessons in and I've run aground.  Is it
> OK for a painfully stupid ol' fart to ask painfully stupid noob
> questions, here?  I'm a long time usenet fan and prefer it to irc.

The python-tutor mailing list exists for precisely those kind of questions:

  https://mail.python.org/mailman/listinfo/tutor

You might also find it interesting to browse/download previous messages
in the archive at that link.

See you there :)


From steve at pearwood.info  Wed Mar  5 02:52:01 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 07:52:01 GMT
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
Message-ID: <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>

On Tue, 04 Mar 2014 23:25:37 -0500, Roy Smith wrote:

> I stopped paying attention to mathematicians when they tried to convince
> me that the sum of all natural numbers is -1/12.  

I'm pretty sure they did not. Possibly a physicist may have tried to tell 
you that, but most mathematicians consider physicists to be lousy 
mathematicians, and the mere fact that they're results seem to actually 
work in practice is an embarrassment for the entire universe. A 
mathematician would probably have said that the sum of all natural 
numbers is divergent and therefore there is no finite answer.

Well, that is, apart from mathematicians like Euler and Ramanujan. When 
people like them tell you something, you better pay attention.

We have an intuitive understanding of the properties of addition. You 
can't add 1000 positive whole numbers and get a negative fraction, that's 
obvious. But that intuition only applies to *finite* sums. They don't 
even apply to infinite *convergent* series, and they're *easy*. Remember 
Zeno's Paradoxes? People doubted that the convergent series:

1/2 + 1/4 + 1/8 + 1/16 + ... 

added up to 1 for the longest time, even though they could see with their 
own eyes that it had to. Until they worked out what *infinite* sums 
actually meant, their intuitions were completely wrong. This is a good 
lesson for us all.

The sum of all the natural numbers is a divergent infinite series, so we 
shouldn't expect that our intuitions hold. We can't add it up as if it 
were a convergent series, because it's not convergent. Nobody disputes 
that. But perhaps there's another way?

Normally mathematicians will tell you that divergent series don't have a 
total. That's because often the total you get can vary depending on how 
you add them up. The classic example is summing the infinite series:

1 - 1 + 1 - 1 + 1 - ... 

Depending on how you group them, you can get:

(1 - 1) + (1 - 1) + (1 - 1) ...  
= 0 + 0 + 0 + ... = 0

or you can get:

1 - (1 - 1 + 1 - 1 + ... ) 
= 1 - (1 - 1) - (1 - 1) - ... )
= 1 - 0 - 0 - 0 ... 
= 1

Or you can do a neat little trick where we define the sum as "x":

x = 1 - 1 + 1 - 1 + 1 - ... 
x = 1 - (1 - 1 + 1 - 1 + ... )
x = 1 - x
2x = 1
x = 1/2


So at first glance, summing a divergent series is like dividing by zero. 
You get contradictory results, at least in this case.

But that's not necessarily always the case. You do have to be careful 
when summing divergent series, but that doesn't always mean you can't do 
it and get a meaningful answer. Sometimes you can, sometimes you can't, 
it depends on the specific series. With the sum of the natural numbers, 
rather than getting three different results from three different methods, 
mathematicians keep getting the same -1/12 result using various methods. 
That's a good hint that there is something logically sound going on here, 
even if it seems unintuitive.

Remember Zeno's Paradoxes? Our intuitions about equality and plus and 
sums of numbers don't apply to infinite series. We should be at least 
open to the possibility that while all the *finite* sums:

1 + 2
1 + 2 + 3
1 + 2 + 3 + 4
...

and so on sum to positive whole numbers, that doesn't mean that the 
*infinite* sum has to total to a positive whole number. Maybe that's not 
how addition works. I don't know about you, but I've never personally 
added up an infinite number of every-increasing quantities to see what 
the result is. Maybe it is a negative fraction. (I'd say "try it and 
see", but I don't have an infinite amount of time to spend on it.)

And in fact that's exactly what seems to be case here. Mathematicians can 
demonstrate an identity (that is, equality) between the divergent sum of 
the natural numbers with the zeta function ?(-1), and *that* can be 
worked out independently, and equals -1/12.

So there are a bunch of different ways to show that the divergent sum 
adds up to -1/12, some of them are more vigorous than others. The zeta 
function method is about as vigorous as they come. The addition of an 
infinite number of things behaves differently than the addition of finite 
numbers of things.

More here:

http://scitation.aip.org/content/aip/magazine/physicstoday/news/10.1063/PT.5.8029

http://math.ucr.edu/home/baez/week126.html

http://en.wikipedia.org/wiki/1_+_2_+_3_+_4_+_%E2%8B%AF

and even here:

http://scientopia.org/blogs/goodmath/2014/01/20/oy-veh-power-series-analytic-continuations-and-riemann-zeta/

where a mathematician tries *really hard* to discredit the idea that the 
sum equals -1/12, but ends up proving that it does. So he simply plays a 
linguistic slight of hand and claims that despite the series and the zeta 
function being equal, they're not *actually* equal.

In effect, the author Mark Carrol-Chu in the "GoodMath" blog above wants 
to make the claim that the divergent sum is not equal to ?(-1), but 
everywhere you find that divergent sum in your calculations you can rub 
it out and replace it with ?(-1), which is -1/12. In other words, he's 
accepting that the divergent sum behaves *as if* it were equal to -1/12, 
he just doesn't want to say that it *is* equal to -1/12.

Is this a mere semantic trick, or a difference of deep and fundamental 
importance? Mark C-C thinks it's an important difference. Mathematicians 
who actually work on this stuff all the time think he's making a semantic 
trick to avoid facing up to the fact that sums of infinite sequences 
don't always behave like sums of finite sequences.



-- 
Steven


From francis.moro at gmail.com  Wed Mar  5 03:07:18 2014
From: francis.moro at gmail.com (Francis Moreau)
Date: Wed, 05 Mar 2014 09:07:18 +0100
Subject: Decoding a process output
In-Reply-To: <lf4tkk$76i$1@ger.gmane.org>
References: <lf46bg$5qc$1@ger.gmane.org> <lf4tkk$76i$1@ger.gmane.org>
Message-ID: <lf6lst$r2q$1@ger.gmane.org>

On 03/04/2014 05:05 PM, Peter Otten wrote:
> Francis Moreau wrote:
> 
>> Hi,
>>
>> In my understanding (I'm relatively new to python), I need to decode any
>> bytes data provided, in my case, by a shell command (such as findmnt)
>> started by the subprocess module. The goal of my application is to parse
>> the command outputs.
>>
>> My application runs only on linux BTW and should run fine on both python
>> 2.7 and py3k.
>>
>> My question is when decoding the output bytes data of the external
>> command, which encoding should I use ?
>>
>> Should I guess the encoding by inspecting LANG or any LC_* environment
>> variables ?
>>
>> Should I force one of those environment variable to a specific value
>> before running my external command ?
>>
>> Thanks for any tips.
> 
> You can use locale.getpreferredencoding(), which seems to evaluate LANG:
> 
> $ python3 -c 'import locale; print(locale.getpreferredencoding())'
> UTF-8
> $ LANG= python3 -c 'import locale; print(locale.getpreferredencoding())'
> ANSI_X3.4-1968

Hmm I'm confused here: when unsetting or changing LANG, the encoding is
changed on the fly that makes me wonder which part of the linux system
encodes the command output. I don't think it's the latter, is the libc ?

Thanks



From steve at pearwood.info  Wed Mar  5 03:26:12 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 08:26:12 GMT
Subject: How security holes happen
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
Message-ID: <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>

On Wed, 05 Mar 2014 08:37:42 +0200, Marko Rauhamaa wrote:

> MRAB <python at mrabarnett.plus.com>:
> 
>> Into how many versions did Lisp split in its first 23 years? :-)
> 
> I'm partial to Scheme, but I'll take any version.
> 
> If you had tried Python 30 years ago, you'd give it up for any serious
> work because it would be so slow and consume so much memory.

/facepalm

Python is only 23 years old, so it would have been a good trick to have 
tried it 30 years ago. While it was slow back then, it used LESS memory, 
not more. (Trading off more memory for speed is one of the ways that 
Python has gotten faster.) Nevertheless, people did use it for serious 
work, at least by the time it got to version 1.4 and quite likely much 
earlier.



-- 
Steven


From steve at pearwood.info  Wed Mar  5 03:38:16 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 08:38:16 GMT
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <5316e278$0$2923$c3e8da3$76491128@news.astraweb.com>

Following up on my own post.

On Wed, 05 Mar 2014 07:52:01 +0000, Steven D'Aprano wrote:

> On Tue, 04 Mar 2014 23:25:37 -0500, Roy Smith wrote:
> 
>> I stopped paying attention to mathematicians when they tried to
>> convince me that the sum of all natural numbers is -1/12.
[...]
> In effect, the author Mark Carrol-Chu in the "GoodMath" blog above wants
> to make the claim that the divergent sum is not equal to ?(-1), but
> everywhere you find that divergent sum in your calculations you can rub
> it out and replace it with ?(-1), which is -1/12. In other words, he's
> accepting that the divergent sum behaves *as if* it were equal to -1/12,
> he just doesn't want to say that it *is* equal to -1/12.
> 
> Is this a mere semantic trick, or a difference of deep and fundamental
> importance? Mark C-C thinks it's an important difference. Mathematicians
> who actually work on this stuff all the time think he's making a
> semantic trick to avoid facing up to the fact that sums of infinite
> sequences don't always behave like sums of finite sequences.

Here's another mathematician who is even more explicit about what she's 
complaining about:

http://blogs.scientificamerican.com/roots-of-unity/2014/01/20/is-the-sum-of-positive-integers-negative/

    [quote]
    There is a meaningful way to associate the number -1/12 to the 
    series 1+2+3+4?, but in my opinion, it is misleading to call 
    it the sum of the series.
    [end quote]

Evelyn Lamb's objection isn't about the mathematics that leads to the 
conclusion that the sum of natural numbers is equivalent to -1/12. That's 
conclusion is pretty much bulletproof. Her objection is over the use of 
the word "equals" to describe that association. Or possibly the use of 
the word "sum" to describe what we're doing when we replace the infinite 
series with -1/12.

Whatever it is that we're doing, it doesn't seem to have the same 
behavioural properties as summing finitely many finite numbers. So 
perhaps she is right, and we shouldn't call the sum of a divergent series 
a sum?


-- 
Steven


From ben+python at benfinney.id.au  Wed Mar  5 03:57:49 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 05 Mar 2014 19:57:49 +1100
Subject: How security holes happen
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
 <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <85y50pdnua.fsf@benfinney.id.au>

Steven D'Aprano <steve at pearwood.info> writes:

> On Wed, 05 Mar 2014 08:37:42 +0200, Marko Rauhamaa wrote:
>
> > If you had tried Python 30 years ago, you'd give it up for any
> > serious work because it would be so slow and consume so much memory.
>
> /facepalm
>
> Python is only 23 years old, so it would have been a good trick to have 
> tried it 30 years ago. While it was slow back then, it used LESS memory, 
> not more.

Moreover, this is not an issue of Python the language as much as
*implementations* (the CPython implementation has improved markedly in
the intervening decades), and of *resources* very different then and
now.

The available CPU and memory resources for a language implementation is
vastly greater today than 30 years ago. You could re-implement exactly
the same compiler today as was run 30 years ago, and have its speed and
memory performance remarkably better without any change in the language.

If you'd run an implementation of *any* language of the time 30 years
ago, it would have been far slower than implementations on today's
hardware, and doubless improvements in the implementation (if the
community was motivated to improve it for that long) would account for
even greater speed differences.

None of this is argument in favour of the changing applicability of the
*language*, which is what Marko apparently wants to imply.

-- 
 \          ?I got an answering machine for my phone. Now when someone |
  `\      calls me up and I'm not home, they get a recording of a busy |
_o__)                                          signal.? ?Steven Wright |
Ben Finney



From antoon.pardon at rece.vub.ac.be  Wed Mar  5 03:59:14 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 05 Mar 2014 09:59:14 +0100
Subject: Functional programming
In-Reply-To: <5315bd68$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7700.1393930643.18130.python-list@python.org>
 <5315bd68$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5316E762.6090701@rece.vub.ac.be>

Op 04-03-14 12:47, Steven D'Aprano schreef:

> On Tue, 04 Mar 2014 11:56:07 +0100, Antoon Pardon wrote:
>
>> Op 04-03-14 09:56, Steven D'Aprano schreef:
>>>> If you
>>>> explicitly say that this is an int, then yes, that should be
>>>> disallowed;
>>> It's that "explicitly" part that doesn't follow. Having to manage types
>>> is the most tedious, boring, annoying, *unproductive* part of languages
>>> like Java, C and Pascal. Almost always, you're telling the compiler
>>> stuff that it can work out for itself.
>> In the same way writing unit tests is the most tedious, boring,
>> annoying, *unproductive* part. 
> Actually, I like writing unit tests. How do you know what the function 
> does until you test it? I'm not a TDD fanatic, but often I write tests 
> before I write the code, and there's really nothing nicer than seeing a 
> whole lot of failing unit tests suddenly start working.

You examine the code. Just like you examine the code to interfere the type. 

> Well, maybe a nice BLT sandwich, when the bacon is nice and lean and the 
> lettuce crisp and the tomato flavourful and not too soggy. But other than 
> that, writing unit tests and seeing them pass is great.
>
> On the other hand, writing
>
>     int n, m
>     double x, y
>
> and similar three hundred times throughout your program is not terribly 
> exciting. Even when it compiles, it doesn't mean it works.

Even if your unit tests pass, that doesn't mean your program works.
 

>> Amost always you are giving the program 
>> results it can work out for itself.
> Not even close. I'd like to see the compiler that can work out for itself 
> that this function is buggy:

Who said anything about buggy. If you want to test the function add1, what do you do?
You call for example add1(5) and check that it is equal to 6. In other words you provide
the result yourself you want the function to produce.

> def sine_rule(side_a, side_b, angle_a):
>     """Return the angle opposite side_b."""
>     return math.sin(side_b/side_a)*angle_a
>
>
> If you don't remember your Sine Rule from trigonometry, that's okay. 
> Trust me, the function is badly wrong. It's rubbish really. But short of 
> some really impressive AI coupled with a Mathematica-level of maths 
> knowledge, how is the compiler supposed to know that?
>
> Static type testing, while valuable, cannot tell you that the program 
> does what you wanted it to do.

In the same way it can't interfere the return type you want the function to have.



From wxjmfauth at gmail.com  Wed Mar  5 04:00:50 2014
From: wxjmfauth at gmail.com (wxjmfauth at gmail.com)
Date: Wed, 5 Mar 2014 01:00:50 -0800 (PST)
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <5316e278$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <5316e278$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <a3a15dce-69ba-41bc-89cd-21b84be35627@googlegroups.com>

Mathematics?
The Flexible String Representation is a very nice example
of a mathematical absurdity.

jmf

PS Do not even think to expect to contradict me. Hint:
sheet of paper and pencil.



From marko at pacujo.net  Wed Mar  5 04:01:08 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 11:01:08 +0200
Subject: How security holes happen
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
 <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <878usprpd7.fsf@elektro.pacujo.net>

Steven D'Aprano <steve at pearwood.info>:

> On Wed, 05 Mar 2014 08:37:42 +0200, Marko Rauhamaa wrote:
>> If you had tried Python 30 years ago, you'd give it up for any
>> serious work because it would be so slow and consume so much memory.
>
> /facepalm
>
> Python is only 23 years old,

Some explorers roamed in Siberia around 1900 and encountered small
nations with undocumented languages. They stayed with the people for
some time and tried to record the basic vocabulary and grammar. The
dialog sometimes went like this:

  - In your language, is it correct to say, "I went fishing yesterday."

  - No.

  - What's wrong with it?

  - I didn't go fishing yesterday.


Marko


From antoon.pardon at rece.vub.ac.be  Wed Mar  5 04:09:28 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 05 Mar 2014 10:09:28 +0100
Subject: Functional programming
In-Reply-To: <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
 <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5316E9C8.9000403@rece.vub.ac.be>

Op 04-03-14 16:18, Steven D'Aprano schreef:
> Depends on the type: I suppose you can draw an analogy between records or 
> structs and classes with no methods.
>
> But I'm not talking about creating types, I'm talking about type 
> declarations.
>
> int x=2;  # 2 is an int? Who would have guessed!

How about:

decimal[precision=4] x = 2.6;
int[min = -10, max = 20] n = 7;

-- 
Antoon Pardon


From jldunn2000 at gmail.com  Wed Mar  5 04:59:00 2014
From: jldunn2000 at gmail.com (loial)
Date: Wed, 5 Mar 2014 01:59:00 -0800 (PST)
Subject: find and replace string in binary file
In-Reply-To: <mailman.7773.1393978398.18130.python-list@python.org>
References: <01951a7d-2ab3-4203-a9c5-2f79017a980d@googlegroups.com>
 <lf4jrk$95v$1@ger.gmane.org>
 <CAPTjJmrZPr_QdejVwntYn17LSbuEp_8BsCmR5vfNU9N0PO4QYQ@mail.gmail.com>
 <mailman.7773.1393978398.18130.python-list@python.org>
Message-ID: <687bff67-c486-402d-9f50-82e018c75585@googlegroups.com>

Thanks Emile.

Unfortunately I have to use python 2.6 for this


On Wednesday, 5 March 2014 00:13:00 UTC, emile  wrote:
> On 03/04/2014 02:44 PM, Chris Angelico wrote:
> 
> > On Wed, Mar 5, 2014 at 12:18 AM, Peter Otten <__peter__ at web.de> wrote:
> 
> >> loial wrote:
> 
> >>
> 
> >>> How do I read a binary file, find/identify a character string and replace
> 
> >>> it with another character string and write out to another file?
> 
> >>>
> 
> >>> Its the finding of the string in a binary file that I am not clear on.
> 
> >>
> 
> >> That's not possible. You have to convert either binary to string or string
> 
> >> to binary before you can replace. Whatever you choose, you have to know the
> 
> >> encoding of the file.
> 
> >
> 
> > If it's actually a binary file (as in, an executable, or an image, or
> 
> > something), then the *file* won't have an encoding, so you'll need to
> 
> > know the encoding of the particular string you want and encode your
> 
> > string to bytes.
> 
> 
> 
> 
> 
> On 2.7 it's as easy as it sounds without having to think much about 
> 
> encodings and such.  I find it mostly just works.
> 
> 
> 
> emile at paj39:~$ which python
> 
> /usr/bin/python
> 
> emile at paj39:~$ python
> 
> Python 2.7.3 (default, Sep 26 2013, 16:38:10)
> 
> [GCC 4.7.2] on linux2
> 
> Type "help", "copyright", "credits" or "license" for more information.
> 
>  >>> image = open('/usr/bin/python','rb').read()
> 
>  >>> image.find("""Type "help", "copyright", "credits" """)
> 
> 1491592
> 
>  >>> image = image[:1491592]+"Echo"+image[1491592+4:]
> 
>  >>> open('/home/emile/pyecho','wb').write(image)
> 
>  >>>
> 
> emile at paj39:~$ chmod a+x /home/emile/pyecho
> 
> emile at paj39:~$ /home/emile/pyecho
> 
> Python 2.7.3 (default, Sep 26 2013, 16:38:10)
> 
> [GCC 4.7.2] on linux2
> 
> Echo "help", "copyright", "credits" or "license" for more information.
> 
> 
> 
> YMMV,
> 
> 
> 
> Emile



From ned at nedbatchelder.com  Wed Mar  5 06:23:28 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Wed, 05 Mar 2014 06:23:28 -0500
Subject: Working with the set of real numbers
In-Reply-To: <a3a15dce-69ba-41bc-89cd-21b84be35627@googlegroups.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <5316e278$0$2923$c3e8da3$76491128@news.astraweb.com>
 <a3a15dce-69ba-41bc-89cd-21b84be35627@googlegroups.com>
Message-ID: <lf71f3$unn$1@ger.gmane.org>

On 3/5/14 4:00 AM, wxjmfauth at gmail.com wrote:
> Mathematics?
> The Flexible String Representation is a very nice example
> of a mathematical absurdity.
>
> jmf
>
> PS Do not even think to expect to contradict me. Hint:
> sheet of paper and pencil.
>

Reminder to everyone: JMF makes no sense when he talks about the FSR, 
and absurdly seems to think hinting at paper and pencil will convince us 
he is right.  Don't engage with him on this topic.

-- 
Ned Batchelder, http://nedbatchelder.com



From bc at freeuk.com  Wed Mar  5 06:28:31 2014
From: bc at freeuk.com (BartC)
Date: Wed, 5 Mar 2014 11:28:31 -0000
Subject: Functional programming
In-Reply-To: <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com><mailman.7612.1393810048.18130.python-list@python.org><4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com><mailman.7633.1393849247.18130.python-list@python.org><3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com><mailman.7641.1393855219.18130.python-list@python.org><216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com><mailman.7644.1393856584.18130.python-list@python.org><0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com><mailman.7647.1393858917.18130.python-list@python.org><5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com><mailman.7651.1393871851.18130.python-list@python.org><5315661c$0$2923$c3e8da3$76491128@news.astraweb.com><mailman.7695.1393913099.18130.python-list@python.org><53159540$0$2923$c3e8da3$76491128@news.astraweb.com><XzkRu.27$O_6.17@fx04.am4>
 <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <fVDRu.1902$rC1.875@fx34.am4>

"Steven D'Aprano" <steve+comp.lang.python at pearwood.info> wrote in message
news:5315eec0$0$29985$c3e8da3$5496439d at news.astraweb.com...
> On Tue, 04 Mar 2014 13:30:04 +0000, BartC wrote:

>> Isn't creating classes in Python similar to creating types elsewhere?
>
> Depends on the type: I suppose you can draw an analogy between records or
> structs and classes with no methods.
>
> But I'm not talking about creating types, I'm talking about type
> declarations.
>
> int x=2;  # 2 is an int? Who would have guessed!

Think of the int as a 'var' then:

var x=2;

Now you're just declaring the names. But writing 'var' as 'int' is exactly
the same amount of work.

However, in the sorts of languages that require you to describe types in
this much detail, then the exact kind of type can be important:
float/integer, signed/unsigned, short/long, character/numeric etc.

Especially when declaring an array or struct element, or a pointer; in these
cases, providing a sample value in initialisation data is more awkward (for
one thing, because you need to initialise the instance, whereas a struct is
usually declared separately as a type).

But I agree that in many cases, an initialised declaration *could* often be
used to infer the likely type without too much trouble:

var x=2     # integer
var y=3.0   # real
var z="A"   # probably, a C-style string pointer ('char*')

(And since I'm working on such a language at the moment, I felt obliged to
implement exactly this. And yes, with 10 minutes' effort, something like
this was working, to prove my assertion.

However it is not satisfactory, which is one reason why no well-established
static language is likely to adopt such a feature. It is just too untidy,
too ad-hoc and undisciplined, to say that usually you need to provide an
exact type, but sometimes, in such and such an instance, you don't need to
bother!)

-- 
Bartc
 



From oscar.j.benjamin at gmail.com  Wed Mar  5 06:59:47 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Wed, 5 Mar 2014 11:59:47 +0000
Subject: Working with the set of real numbers
In-Reply-To: <lf5mr8$ttr$1@ger.gmane.org>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
 <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>
 <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>
 <lf5mr8$ttr$1@ger.gmane.org>
Message-ID: <CAHVvXxQo2-B8t+xmG04Awr1Z9V0o+w9az5UtpSEY=AmaW9pe0A@mail.gmail.com>

On 4 March 2014 23:20, Dave Angel <davea at davea.name> wrote:
>
> One problem with complexity claims is that it's easy to miss some
>  contributing time eaters. I haven't done any measuring on modern
>  machines nor in python, but I'd assume that multiplies take
>  *much* longer for large integers, and that divides are much
>  worse. So counting iterations isn't the whole story.

Agreed but there's a big difference between log(N) iterations and N iterations!

> On the assumption that division by 2 is very fast,  and that a
>  general multiply isn't too bad, you could improve on Newton by
>  observing that the slope is 2.
>
>    err = n - guess * guess
>     guess += err/2

I gues you mean like this:

def sqrt(n):
    err = guess = 1
    while err > 1e-10:
        err = n - guess * guess
        guess += err/2
    return guess

This requires log2(10)*N iterations to get N digits. So the penalty
for using division would have to be extreme in order for this to
better. Using Decimal to get many digits we can write that as:

def sqrt2(n, prec=1000):
    '''Solve x**2 = y'''
    eps = D(10) ** -(prec + 5)
    err = guess = D(1)
    with localcontext() as ctx:
        ctx.prec = prec + 10
        while abs(err) > eps:
            err = n - guess*guess
            guess += err/2
    return guess

This method works out much slower than Newton with division at 10000
digits: 40s (based on a single trial) vs 80ms (timeit result).

> Some 37 years ago I microcoded  a math package which included
>  square root.  All the math was decimal, and there was no hardware
>  multiply or divide. The algorithm I came up with generated the
>  answer one digit at a time, with no subsequent rounding needed.
>  And it took just a little less time than two divides. For that
>  architecture,  Newton's method would've been too
>  slow.

If you're working with a fixed small precision then it might be.

> Incidentally, the algorithm did no divides, not even by 2. No
>  multiplies either.  Just repeated subtraction,  sorta like divide
>  was done.
>
> If anyone is curious,  I'll be glad to describe the algorithm;
>  I've never seen it published, before or since.  I got my
>  inspiration from a method used in mechanical,  non-motorized,
>  adding machines.  My father had shown me that approach in the
>  50's.

I'm curious.


Oscar


From davea at davea.name  Wed Mar  5 07:06:11 2014
From: davea at davea.name (Dave Angel)
Date: Wed, 5 Mar 2014 07:06:11 -0500 (EST)
Subject: find and replace string in binary file
References: <01951a7d-2ab3-4203-a9c5-2f79017a980d@googlegroups.com>
Message-ID: <lf73n2$ump$1@ger.gmane.org>

 loial <jldunn2000 at gmail.com> Wrote in message:
> How do I read a binary file, find/identify a character string and replace it with another character string and write out to another file?
> 
> Its the finding of the string in a binary file that I am not clear on.
> 
> Any help appreciated
> 

I see from another message that you're using Python 2.6. That
 makes a huge difference and should have been in your query, along
 with a minimal code sample.

Is the binary file under 100 MB or so? Then open it (in binary
 mode 'rb'), and read it. You'll now have a (large) byte string
 containing the entire file. 

The next question is whether you're sure that your search and
 replace strings are ASCII. Assuming that is probably a mistake, 
 but it will get you started. 

Now the substitution is trivial:
        new_bytes = old_bytes.replace (search, replace)
It's also possible to emulate that with find and slice, mainly if
 you need to report progress to the user.

If the search and/or replace strings are not ASCII, you have to
 know what encoding the file may have used for them.  You need to
 build a Unicode string, encode it the same way as the file uses,
 and then call the replace method. 

Now for a huge caveat.  If you don't know the binary format,
 you're risking the creation of pure junk. Here are just two
 examples of what might go wrong, assuming the file is an
 executable.  The same risks exist for other files, but I'm just
 supposing. 

If the two byte strings are not the same length, then all the
 remaining code and data in the file will be moved to a new spot. 
 If you're lucky,  the code will crash quickly,  since all
 pointers referencing that code and data are incorrect.

If some non-textual part of the file happens to match your search
 string you're going to likely trash that portion of the code.  If
 the search string is large enough,  maybe this is unlikely.  But
 I recall taking the challenge of writing assembly programs which
 could be generated entirely from one or more type commands
 (msdos)



-- 
DaveA



From rosuav at gmail.com  Wed Mar  5 07:04:20 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 23:04:20 +1100
Subject: Functional programming
In-Reply-To: <fVDRu.1902$rC1.875@fx34.am4>
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
 <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <fVDRu.1902$rC1.875@fx34.am4>
Message-ID: <CAPTjJmqbVjtzARFoa0yo8iS8hEJwJ2jREQt6LucMAtr5vet6rg@mail.gmail.com>

On Wed, Mar 5, 2014 at 10:28 PM, BartC <bc at freeuk.com> wrote:
> But I agree that in many cases, an initialised declaration *could* often be
> used to infer the likely type without too much trouble:
>
> var x=2     # integer
> var y=3.0   # real
> var z="A"   # probably, a C-style string pointer ('char*')
>
> (And since I'm working on such a language at the moment, I felt obliged to
> implement exactly this. And yes, with 10 minutes' effort, something like
> this was working, to prove my assertion.
>
> However it is not satisfactory, which is one reason why no well-established
> static language is likely to adopt such a feature. It is just too untidy,
> too ad-hoc and undisciplined, to say that usually you need to provide an
> exact type, but sometimes, in such and such an instance, you don't need to
> bother!)

C++ has something very like this, with the 'auto' keyword. It's not
particularly useful for the examples you give, but can be much more so
when you have templates, iterators, and so on - where the exact type
declaration might be a couple dozen characters of pure syntactic salt,
since you're initializing it to some function's return value.

ChrisA


From marko at pacujo.net  Wed Mar  5 07:11:56 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 14:11:56 +0200
Subject: Functional programming
References: <B512F079-4F01-4865-BEF3-07DF94F21832@gmail.com>
 <mailman.7612.1393810048.18130.python-list@python.org>
 <4c7dbc57-eef9-4582-aecd-aac13a39b45f@googlegroups.com>
 <mailman.7633.1393849247.18130.python-list@python.org>
 <3b54a279-03a1-4a81-a428-ecad6eb16036@googlegroups.com>
 <mailman.7641.1393855219.18130.python-list@python.org>
 <216bb5f4-32c4-4f86-a9f4-1b0dd37a2a81@googlegroups.com>
 <mailman.7644.1393856584.18130.python-list@python.org>
 <0129a5b9-b85f-4ad5-b5e2-bfb2a48041d5@googlegroups.com>
 <mailman.7647.1393858917.18130.python-list@python.org>
 <5314bb96$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7651.1393871851.18130.python-list@python.org>
 <5315661c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7695.1393913099.18130.python-list@python.org>
 <53159540$0$2923$c3e8da3$76491128@news.astraweb.com>
 <XzkRu.27$O_6.17@fx04.am4>
 <5315eec0$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <fVDRu.1902$rC1.875@fx34.am4>
 <mailman.7812.1394021064.18130.python-list@python.org>
Message-ID: <87vbvsrgj7.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> C++ has something very like this, with the 'auto' keyword. It's not
> particularly useful for the examples you give, but can be much more so
> when you have templates, iterators, and so on - where the exact type
> declaration might be a couple dozen characters of pure syntactic salt,
> since you're initializing it to some function's return value.

Java has a widely practiced ideal that you should not tie variables to
class types but instead stick to interface types. Thus, you want to
declare:

   List<Integer> li = new LinkedList<Integer>();

Thing is, though, you can't automatically guess this. After all, you
might be after:

   Iterable<Integer> li = new LinkedList<Integer>();

or maybe:

   Collection<Integer> li = new LinkedList<Integer>();

This principle doesn't concern only collections. A well-designed
application should specify interfaces for pretty much all classes to
separate design blocks and APIs from implementations du jour.

(Again, something that has no relevance for Python users.)


Marko


From breamoreboy at yahoo.co.uk  Wed Mar  5 07:21:38 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 05 Mar 2014 12:21:38 +0000
Subject: Reference
In-Reply-To: <f82e009f-3701-44ec-85a5-6680529f65b3@googlegroups.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <lf6ej2$hum$1@dont-email.me>
 <f82e009f-3701-44ec-85a5-6680529f65b3@googlegroups.com>
Message-ID: <lf74sb$6df$1@ger.gmane.org>

On 05/03/2014 06:10, Rustom Mody wrote:
> On Wednesday, March 5, 2014 11:31:04 AM UTC+5:30, alex23 wrote:
>> On 5/03/2014 3:47 PM, Rustom Mody wrote:
>>> That python is a hll means that machine reprs are intended to be abstracted
>>> away. 'is' fails to do that -- proof of that being the discrepancy between
>>> is and ==
>
>> The "discrepancy" is because _they're fundamentally different_:
>
> Yeah I know :D
>
>
>> Both have their uses.
>
> Yes -- see my lisp example above
>
>>       >>> a = b = [1,2]
>>       >>> c = [1,2]
>>       >>> a is b
>>       True
>>       >>> a is c
>>       False
>>       >>> a == b
>>       True
>>       >>> a == c
>>       True
>
>> `==` is used to determine if they're equivalent in value.
>
> Right
>
>> `is` is used to determine if two names refer to the same object.
>
>
> 'Same' is 'is' in a different guise and is what I object to.
>
> A python programmer who needs/wants to think of same/is in this sense
> should probably be using C or assembly
>
> In the exceptional circumstances when 'low-level-machine-equivalence-relation'
> is desired, a name carrying some of those connotations would be ok
>

Quite frankly I haven't got the faintest idea what you're going on 
about, so I'll just stick with writing plain, boring, working Python code.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From breamoreboy at yahoo.co.uk  Wed Mar  5 07:24:23 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 05 Mar 2014 12:24:23 +0000
Subject: Reference
In-Reply-To: <lf6g75$pao$1@dont-email.me>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <lf6ej2$hum$1@dont-email.me>
 <f82e009f-3701-44ec-85a5-6680529f65b3@googlegroups.com>
 <lf6g75$pao$1@dont-email.me>
Message-ID: <lf751g$6df$2@ger.gmane.org>

On 05/03/2014 06:28, alex23 wrote:
> On 5/03/2014 4:10 PM, Rustom Mody wrote:
>> A python programmer who needs/wants to think of same/is in this sense
>> should probably be using C or assembly
>
> Any programmer who is obsessing about some idea of philosophical purity
> should probably not be using Python.
>

The Python philosophy is beautifully put in The Zen.  I particularly 
like "Practicality beats purity" although there's plenty of other pieces 
of the whole to consider.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From oscar.j.benjamin at gmail.com  Wed Mar  5 07:21:37 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Wed, 5 Mar 2014 12:21:37 +0000
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CAHVvXxS+t6e8b_jjyeQcCwLod4_NVfbHjUwPnr5L-TuEzhLwgQ@mail.gmail.com>

On 5 March 2014 07:52, Steven D'Aprano <steve at pearwood.info> wrote:
> On Tue, 04 Mar 2014 23:25:37 -0500, Roy Smith wrote:
>
>> I stopped paying attention to mathematicians when they tried to convince
>> me that the sum of all natural numbers is -1/12.
>
> I'm pretty sure they did not. Possibly a physicist may have tried to tell
> you that, but most mathematicians consider physicists to be lousy
> mathematicians, and the mere fact that they're results seem to actually
> work in practice is an embarrassment for the entire universe. A
> mathematician would probably have said that the sum of all natural
> numbers is divergent and therefore there is no finite answer.

Why the dig at physicists? I think most physicists would be able to
tell you that the sum of all natural numbers is not -1/12. In fact
most people with very little background in mathematics can tell you
that.

The argument that the sum of all natural numbers comes to -1/12 is
just some kind of hoax. I don't think *anyone* seriously believes it.

> Well, that is, apart from mathematicians like Euler and Ramanujan. When
> people like them tell you something, you better pay attention.

Really? Euler didn't even know about absolutely convergent series (the
point in question) and would quite happily combine infinite series to
obtain a formula.

<snip>
> Normally mathematicians will tell you that divergent series don't have a
> total. That's because often the total you get can vary depending on how
> you add them up. The classic example is summing the infinite series:
>
> 1 - 1 + 1 - 1 + 1 - ...

There is a distinction between absolute convergence and convergence.
Rearranging the order of the terms in the above infinite sum is
invalid because the series is not absolutely convergent. For this
particular series there is no sense in which its sum converges on an
answer but there are other series that cannot be rearranged while
still being convergent:
http://en.wikipedia.org/wiki/Harmonic_series_(mathematics)#Alternating_harmonic_series

Personally I think it's reasonable to just say that the sum of the
natural numbers is infinite rather than messing around with terms like
undefined, divergent, or existence. There is a clear difference
between a series (or any limit) that fails to converge  asymptotically
and another that just goes to +-infinity. The difference is usually
also relevant to any practical application of this kind of maths.


Oscar


From breamoreboy at yahoo.co.uk  Wed Mar  5 07:35:05 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 05 Mar 2014 12:35:05 +0000
Subject: Reference
In-Reply-To: <8761ntp3ja.fsf@elektro.pacujo.net>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <8761ntp3ja.fsf@elektro.pacujo.net>
Message-ID: <lf75lh$mci$1@ger.gmane.org>

On 05/03/2014 06:23, Marko Rauhamaa wrote:
> Rustom Mody <rustompmody at gmail.com>:
>
>> * ... which summarizes my objection in this thread: Python's 'is'
>> leaks the machine abstraction. 'id' does it legitimately (somewhat),
>> 'is' does it illegitimately
>
> I agree that the Python data model can be exceedingly challenging to a
> beginner. However, I wouldn't throw the baby away with the bathwater,
> but look for ingenious ways to teach it.

[snip Java]

>
> Similarly, in Python:
>
>     if the_list == None:
>
> *should* work (even if there's no such stipulation in Python's reference
>   material), but why wouldn't you use the more natural:
>
>     if the_list is None:
>
>
> Marko
>

Really great thinking, test the name the_list, which strangely enough 
tells me that this beast is a list, in the same way that 
THIS_IS_A_CONSTANT is a constant, to see if it's None.  Congratulations, 
you've been promoted to captain of my dream team.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From breamoreboy at yahoo.co.uk  Wed Mar  5 07:42:28 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 05 Mar 2014 12:42:28 +0000
Subject: find and replace string in binary file
In-Reply-To: <687bff67-c486-402d-9f50-82e018c75585@googlegroups.com>
References: <01951a7d-2ab3-4203-a9c5-2f79017a980d@googlegroups.com>
 <lf4jrk$95v$1@ger.gmane.org>
 <CAPTjJmrZPr_QdejVwntYn17LSbuEp_8BsCmR5vfNU9N0PO4QYQ@mail.gmail.com>
 <mailman.7773.1393978398.18130.python-list@python.org>
 <687bff67-c486-402d-9f50-82e018c75585@googlegroups.com>
Message-ID: <lf763d$rhk$1@ger.gmane.org>

On 05/03/2014 09:59, loial wrote:

I'm pleased to see that you have answers.  In return would you please 
read and action this https://wiki.python.org/moin/GoogleGroupsPython to 
prevent us seeing double line spacing, thanks.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From rosuav at gmail.com  Wed Mar  5 07:45:25 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 5 Mar 2014 23:45:25 +1100
Subject: Reference
In-Reply-To: <lf75lh$mci$1@ger.gmane.org>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <8761ntp3ja.fsf@elektro.pacujo.net> <lf75lh$mci$1@ger.gmane.org>
Message-ID: <CAPTjJmqx4ffyqCQKB_ZYNycvKjrAnmFKgQweRMu4fyjmg5FFSw@mail.gmail.com>

On Wed, Mar 5, 2014 at 11:35 PM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>>     if the_list is None:
>>
>>
>> Marko
>>
>
> Really great thinking, test the name the_list, which strangely enough tells
> me that this beast is a list, in the same way that THIS_IS_A_CONSTANT is a
> constant, to see if it's None.  Congratulations, you've been promoted to
> captain of my dream team.

Uhh... why? What's wrong with something either being a list or being
None to indicate no list?

def foo(x, target_list=None):
    if target_list is not None: target_list = default_targets

You can't use "if target_list:" here, because that would also catch an
empty list. You need some kind of sentinel that says "there isn't a
list here".

ChrisA


From breamoreboy at yahoo.co.uk  Wed Mar  5 07:50:06 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 05 Mar 2014 12:50:06 +0000
Subject: Working with the set of real numbers
In-Reply-To: <CAHVvXxS+t6e8b_jjyeQcCwLod4_NVfbHjUwPnr5L-TuEzhLwgQ@mail.gmail.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <CAHVvXxS+t6e8b_jjyeQcCwLod4_NVfbHjUwPnr5L-TuEzhLwgQ@mail.gmail.com>
Message-ID: <lf76hn$16n$1@ger.gmane.org>

On 05/03/2014 12:21, Oscar Benjamin wrote:
>
> Why the dig at physicists? I think most physicists would be able to
> tell you that the sum of all natural numbers is not -1/12. In fact
> most people with very little background in mathematics can tell you
> that.
>

I'll put that one to the test tomorrow morning when the bin men come 
round.  I fully expect them to dial 999 and ask that the paramedics are 
armed with plenty of sedatives.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From davea at davea.name  Wed Mar  5 07:57:49 2014
From: davea at davea.name (Dave Angel)
Date: Wed, 5 Mar 2014 07:57:49 -0500 (EST)
Subject: Working with the set of real numbers
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
 <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>
 <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>
 <lf5mr8$ttr$1@ger.gmane.org>
 <CAHVvXxQo2-B8t+xmG04Awr1Z9V0o+w9az5UtpSEY=AmaW9pe0A@mail.gmail.com>
Message-ID: <lf76nv$3s9$1@ger.gmane.org>

 Oscar Benjamin <oscar.j.benjamin at gmail.com> Wrote in message:
> On 4 March 2014 23:20, Dave Angel <davea at davea.name> wrote:
>>
>> One problem with complexity claims is that it's easy to miss some
>>  contributing time eaters. I haven't done any measuring on modern
>>  machines nor in python, but I'd assume that multiplies take
>>  *much* longer for large integers, and that divides are much
>>  worse. So counting iterations isn't the whole story.
> 
> Agreed but there's a big difference between log(N) iterations and N iterations!
> 
>> On the assumption that division by 2 is very fast,  and that a
>>  general multiply isn't too bad, you could improve on Newton by
>>  observing that the slope is 2.
>>
>>    err = n - guess * guess
>>     guess += err/2
> 
> I gues you mean like this:
> 
> def sqrt(n):
>     err = guess = 1
>     while err > 1e-10:
>         err = n - guess * guess
>         guess += err/2
>     return guess
> 
> This requires log2(10)*N iterations to get N digits. 

No idea how you came up with that,  but I see an error in my
 stated algorithm,  which does surely penalize it. The slope isn't
 2, but 2x.  So the line should have been
        guess += err/(2*guess)

Now if you stop the loop after 3 iterations (or use some other
 approach to get a low-precision estimate,  then you can calculate
 scale = 1/(2*estimate)

and then for remaining iterations, 
        guess += err *scale

> So the penalty
> for using division would have to be extreme in order for this to
> better. Using Decimal to get many digits we can write that as:
> 
> def sqrt2(n, prec=1000):
>     '''Solve x**2 = y'''
>     eps = D(10) ** -(prec + 5)
>     err = guess = D(1)
>     with localcontext() as ctx:
>         ctx.prec = prec + 10
>         while abs(err) > eps:
>             err = n - guess*guess
>             guess += err/2
>     return guess
> 
> This method works out much slower than Newton with division at 10000
> digits: 40s (based on a single trial) vs 80ms (timeit result).

Well considering you did not special-case the divide by 2, I'm not
 surprised it's slower.

> 
>> Some 37 years ago I microcoded  a math package which included
>>  square root.  All the math was decimal, and there was no hardware
>>  multiply or divide. The algorithm I came up with generated the
>>  answer one digit at a time, with no subsequent rounding needed.
>>  And it took just a little less time than two divides. For that
>>  architecture,  Newton's method would've been too
>>  slow.
> 
> If you're working with a fixed small precision then it might be.
> 
>> Incidentally, the algorithm did no divides, not even by 2. No
>>  multiplies either.  Just repeated subtraction,  sorta like divide
>>  was done.
>>
>> If anyone is curious,  I'll be glad to describe the algorithm;
>>  I've never seen it published, before or since.  I got my
>>  inspiration from a method used in mechanical,  non-motorized,
>>  adding machines.  My father had shown me that approach in the
>>  50's.
> 
> I'm curious.
> 

A later message,  I guess.  I can't write that much on the tablet.


-- 
DaveA



From davea at davea.name  Wed Mar  5 08:32:30 2014
From: davea at davea.name (Dave Angel)
Date: Wed, 5 Mar 2014 08:32:30 -0500 (EST)
Subject: Working with the set of real numbers
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
 <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>
 <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>
 <lf5mr8$ttr$1@ger.gmane.org>
 <CAHVvXxQo2-B8t+xmG04Awr1Z9V0o+w9az5UtpSEY=AmaW9pe0A@mail.gmail.com>
 <lf76nv$3s9$1@ger.gmane.org>
Message-ID: <lf78os$r7m$1@ger.gmane.org>

 Dave Angel <davea at davea.name> Wrote in message:
>  Oscar Benjamin <oscar.j.benjamin at gmail.com> Wrote in message:
>> On 4 March 2014 23:20, Dave Angel <davea at davea.name> wrote:

>>>
>>> If anyone is curious,  I'll be glad to describe the algorithm;
>>>  I've never seen it published, before or since.  I got my
>>>  inspiration from a method used in mechanical,  non-motorized,
>>>  adding machines.  My father had shown me that approach in the
>>>  50's.
>> 
>> I'm curious.
>> 
> 
> A later message,  I guess.  I can't write that much on the tablet.
> 
> 
 Given a microcodable architecture with no hardware support for multiply or divide, clearly multiply will be several times as fast as divide (at least). ??There was a BCD ALU, so add and subtract of decimal values was quite reasonable. ??All floating point logic, however, is just microcode.

Divide is implemented via repeated subtraction of the divisor from
 the dividend. ??The count of how many subtracts is done is the
 quotient. Naturally, this is combined with digit shifts, so you
 find one quotient digit at a time. ??For a 13 digit result, the
 maximum subtracts are 13*10.

Multiply is much faster, as you know ahead of time for each column
 how many adds you're supposed to do. ??So you can have
 precalculated multiples of the divisor on hand, and you can
 subtract instead of add when appropriate.

Square root is implemented as a kind of variable division, where
 the "divisor" is changing constantly. ??Everyone knows that the
 sum of the first n odd numbers is n squared. ??So if you started
 with a square, you could repeatedly subtract odd numbers from it
 till you reached zero, and the square root will be roughly half
 the last odd number subtracted.

So to make this work across multiple columns it turns out you can
 accumulate these odd numbers, doing the appropriate shifts after
 each column, and if you take the last number shifted, you can
 just add 1 and divide by 2.

In many architectures, that would be as far as you can go, but in
 the particular one I was using, generating those pesky odd
 numbers was more expensive than you'd expect. ??So it turned out
 to be quicker to just do twice as many subtracts.

Instead of subtracting 1,3, 5, etc., till the value went negative,
 we subtract 0 and 1, 1 and 2, 2 and 3, etc. ??You have twice as
 many subtracts, but no divide by 2 at the end. ??And for each
 column, you need not go beyond 8 + 9, since if it were more than
 that, we would have picked it up in the previous column. ??So you
 do not have to propagate the carry across the trial
 divisor.

Supposing the correct result will be 7.1234567, you will at one
 stage of operations, be subtracting
?? ?? ?? ??71230
?? ?? ?? ??71231
?? ?? ?? ??71231
?? ?? ?? ??71232
?? ?? ?? ??71232
?? ?? ?? ??71233
?? ?? ?? ??71233
?? ?? ?? ??71234
The next subtract will make the result go negative, so you either
 do it, detect negative and undo it, or you do some compare
 operation.


I am here glossing over all the details of normalizing the
 dividend so the exponent is even, and calculating the final
 exponent, which at first approximation is half the original
 one.


-- 
DaveA



From antoon.pardon at rece.vub.ac.be  Wed Mar  5 08:37:15 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 05 Mar 2014 14:37:15 +0100
Subject: Reference
In-Reply-To: <CAPTjJmorGc83tHebvn_1Kf35fZSkgLsgOqfqaB-wOE21OeYvtA@mail.gmail.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <CADwdpybfBTEq62KDXFPNwE9Wr9T=9pUDK=KMw94MofrJwGHdVQ@mail.gmail.com>
 <CAPTjJmorGc83tHebvn_1Kf35fZSkgLsgOqfqaB-wOE21OeYvtA@mail.gmail.com>
Message-ID: <5317288B.8090801@rece.vub.ac.be>

Op 04-03-14 16:25, Chris Angelico schreef:

> On Wed, Mar 5, 2014 at 2:19 AM, Jerry Hill <malaclypse2 at gmail.com> wrote:
>> Out of curiosity, do you think we should be doing truth checking with
>> 'is'?  True and False are singletons, and it seems to me that the
>> justification for idenity versus equality should be just as strong
>> there, but I don't think I've ever seen anyone even suggest that.
> Normal truth testing is done like this:
>
> if cond:

In an other language with real booleans where an if only accepts a
boolean that would be true. In python this is testing for "something."

> This isn't truth testing, this is checking the identity of what's in cond:
>
> if cond is True:
>
> And that's specifically testing for something much tighter than
> truthiness. As you can see from my stats above, that's actually fairly
> rare. Usually you'd just accept that True, 1, "yes", [1,2,3], and
> 1.2345 are all equally true.

No I usually don't accept that. A number different from 0 is not the same
as a none-empty list. I usally don't want to treat them the same.

-- 
Antoon Pardon 



From galaxyblue63 at gmail.com  Wed Mar  5 08:42:20 2014
From: galaxyblue63 at gmail.com (Bill)
Date: Wed, 5 Mar 2014 05:42:20 -0800 (PST)
Subject: How to create an instance of a python class from C++
In-Reply-To: <mailman.7780.1393984546.18130.python-list@python.org>
References: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>
 <mailman.7780.1393984546.18130.python-list@python.org>
Message-ID: <0844f51e-151f-46ce-b0ea-456098d020e3@googlegroups.com>

> 
> So far, so good.  The object that was passed in was the "Derived"
> class object.  Since you presumably only want class objects to be
> passed in, you might want to check that here using PyType_Check.
>
    Yes. Will do.
> 
> >         PyTypeObject *typ = class_decl->ob_type;
> 
> In Python, you instantiate a class by calling it.  You should do the 
> same in C, using PyObject_CallFunction.  But as above, note that you
> want to call class_decl, not class_decl->ob_type.
> 

    Of course. That works.

Thanks.

Bill


From harrismh777 at gmail.com  Wed Mar  5 09:11:04 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Wed, 5 Mar 2014 06:11:04 -0800 (PST)
Subject: How security holes happen
In-Reply-To: <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
 <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <d83922b0-2969-4fa1-aa3a-075f7ad4c44a@googlegroups.com>

On Wednesday, March 5, 2014 2:26:12 AM UTC-6, Steven D'Aprano wrote:
> On Wed, 05 Mar 2014 08:37:42 +0200, Marko Rauhamaa wrote:
> 
> > If you had tried Python 30 years ago, you'd give it up for any serious
> > work because it would be so slow and consume so much memory.
> 
> /facepalm
>
> Python is only 23 years old, so it would have been a good trick to have 
> tried it 30 years ago. 

hi Steven,  QOTD,  I go back to the day of the MITS Altair 8800.  My 
high school had one. I was writing machine code for the Wang 700 series
programmable desk calculator, and punching in code on the Altair 8800,
with toggle switches. I'm one of the guys Bill Gates wrote his famous 
open letter to in 1976. I was there.  In 1984 the only language being used
to write *anything* in the general sphere of personal computing was either
MS DEBUG.COM (one of my favorites) or BASIC---which was ubiquitous, 
where like almost *every* computer booted directly into a BASIC interpreter,
the noted exception being the first IBM PC.

The pre-cursor to python was ABC created at CWI in about 1991. One of 
its purposes (according to Guido) was to, and I quote, "Stamp out BASIC".

My first IBM machine was the famous PCjr... booted directly into cartridge 
BASIC, or would optionally boot DOS 2.1 from 5" floppy, where I could 
run, you guessed it BASICA, using the cartridge rom,  or I could optionally
run DEBUG.COM and code up 8086 machine code (not assembler, mind you).

Well, I used my PCjr until 1992 (python was one year old, and ABC would
not run on a PC); when I purchased my 486 SX. Guess what?  ---still 
coding BASIC, DEBUG.COM... and whoohoo, Turbo Pascal........  

At IBM we were coding Rexx on the VM370 systems, and then Rexx on the
OS/2 systems; no python, and nothing much else either , oh yes, Turbo BASIC,
Visual BASIC, and of course BASICA although you could then get it as GWBASIC,
... still no python. 

Did anyone mention that PCs back in that day were toys. And I do mean toys. 
They were slow, they crashed, their graphics sucked, and your storage medium 
was a floppy disk.  Linus was working in Finland on basic... Richard Stallman was
working on GNU, Guido was working at CWI on python. The PC really didn't come
into its own (and they were still slow) until the Pentium4. Personal computers
really did not begin to really shine until about 1998 (a mere 16 years ago) when
IBM and other began to take a serious look into gnu/linux research. 

PCs were fast enough, had enough memory, and even had python. Of course
most of us were not using it... mostly C of various brands (notably MIX) and
Visual BASIC.  Quick BASIC was ubiquitous by that time, and MASM had taken
over for DEBUG.com.   Those were the days.  

There has been a resurgence of interest in BASIC today; notably Mintoris, and 
Chipmunk. But now everyone usually has some flavor of python installed on
their computer (and most don't know it) because python is being used under
the covers as a scripting language of choice. Wide adoption is still coming, 
in the future, but the future looks good for python; competing of course with
(notably) Java or Dalvik (Android Java). 

In my day computers were slide-rules. Businesses were still using Comptometers
(still being taught on my high school) and the modern age of computing 
would not occur for forty years. Trust me, thirty years ago was like the dark
ages of personal computing and python wasn't even a gleam in her daddy's eye.....

If fact, now that I think of it, Monte Python and the Holy Grail came out in 1975,
one year before the MITS Altair 8800 Bill Gates open letter, and one year after I
graduated from high school. 

{world according to me}
marcus


From neilc at norwich.edu  Wed Mar  5 09:19:27 2014
From: neilc at norwich.edu (Neil Cerutti)
Date: Wed, 5 Mar 2014 14:19:27 +0000 (UTC)
Subject: How security holes happen
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <qsrch9lgi81sd33hu8kag5s6cvhhj637g9@4ax.com>
Message-ID: <lf7bpf$pdg$1@ger.gmane.org>

On 2014-03-05, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> On Wed, 05 Mar 2014 00:48:40 +0200, Marko Rauhamaa
> <marko at pacujo.net> declaimed the following:
>>Ethan Furman <ethan at stoneleaf.us>:
>>> Okay, that looks totally cool. Maybe I'll finally get a
>>> handle on LISP! :)
>>
>> Lisp is conceptually simpler than Python, but awe-inspiring.
>> One day, it will overtake Python, I believe.
>>
>
> It's already had 54 years to become a major language...
>
> Instead it has schismed into Common Lisp and Scheme (and a few
> other dialects)
>
> Granted, my experience was toying with /cassette-based/
> SuperSoft LISP on a TRS-80 Model III

Personally, I think it hasn't taken off because special forms are
harder to remember than syntax. And there are, like, *way* more
than mammals needs. And then the coolest feature of the language,
macros, is designed to let you, gulp, add more.

Well, that or lisp's designers severely underestimated how much
we like to use our programming languages as non-RPN calculators.

-- 
Neil Cerutti



From python.list at tim.thechases.com  Wed Mar  5 09:24:30 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Wed, 5 Mar 2014 08:24:30 -0600
Subject: Reference
In-Reply-To: <857g89f9f2.fsf@benfinney.id.au>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <857g89f9f2.fsf@benfinney.id.au>
Message-ID: <20140305082430.4f9742a7@bigbox.christie.dr>

On 2014-03-05 17:26, Ben Finney wrote:
> > "Jython is an imitation of Cpython and does a good job but not
> > quite as in the case of 'id'"  
> 
> Wrong. Jython and CPython both adhere to the guarantees of object
> identity. Both implementations follow the language reference, and
> neither implementation does object identity better or worse than the
> other.

I think he means "but not quite as [good in making my argument,
despite the fact that the language definition runs contrary to my
mistaken belief] as in [my interpretation of] 'id'"

:-)


-tkc





From marko at pacujo.net  Wed Mar  5 09:54:59 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 16:54:59 +0200
Subject: How security holes happen
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <qsrch9lgi81sd33hu8kag5s6cvhhj637g9@4ax.com>
 <mailman.7823.1394029216.18130.python-list@python.org>
Message-ID: <87zjl47l18.fsf@elektro.pacujo.net>

Neil Cerutti <neilc at norwich.edu>:

> Personally, I think it hasn't taken off because special forms are
> harder to remember than syntax. And there are, like, *way* more than
> mammals needs.

It hasn't taken off yet, but even mammals can evolve.

> Well, that or lisp's designers severely underestimated how much we
> like to use our programming languages as non-RPN calculators.

I don't think Lisp was really originally designed. It just came out and,
surprisingly, ran.

As for the anti-RPN notation, yes, it can be hard to get used to. Then
again, Python notation requires an initiation as well. For example:

   invoc = "{}({})".format(fname, ', '.join(repr(x) for _, x in named_args))


Marko


From rosuav at gmail.com  Wed Mar  5 10:16:53 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 6 Mar 2014 02:16:53 +1100
Subject: How security holes happen
In-Reply-To: <d83922b0-2969-4fa1-aa3a-075f7ad4c44a@googlegroups.com>
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
 <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
 <d83922b0-2969-4fa1-aa3a-075f7ad4c44a@googlegroups.com>
Message-ID: <CAPTjJmpCiNC7HHSQwmD4piTQt2VJY4mjQVSMvH=uCVqywm8ifQ@mail.gmail.com>

On Thu, Mar 6, 2014 at 1:11 AM, Mark H. Harris <harrismh777 at gmail.com> wrote:
> My first IBM machine was the famous PCjr... booted directly into cartridge
> BASIC, or would optionally boot DOS 2.1 from 5" floppy, where I could
> run, you guessed it BASICA, using the cartridge rom,  or I could optionally
> run DEBUG.COM and code up 8086 machine code (not assembler, mind you).

My first IBM machine (first I used - the first computer I actually
personally *owned* wasn't till this century) was an Epson
XT-compatible. We had GW-BASIC and Q-BASIC, and a much superior form
of DEBUG.EXE that came with, get this, an inbuilt mini-assembler! Yes,
I could do this:

-a
xxxx:0100 mov ah,09
xxxx:0102 mov dx,0109
xxxx:0105 int 21
xxxx:0107 int 20
xxxx:0109 db "Hello, world!",13,10,24

And it'd produce the appropriate bytes. From memory, that would be B4
09 BA 09 01 CD 21 CD 20, followed by the text string. I actually used
that to write seriously-useful programs, like one that helped us keep
track of which treasures we'd picked up in Colossal Caves. (For some
definition of "seriously-useful", anyway.)

> At IBM we were coding Rexx on the VM370 systems, and then Rexx on the
> OS/2 systems; no python, and nothing much else either , oh yes, Turbo BASIC,
> Visual BASIC, and of course BASICA although you could then get it as GWBASIC,
> ... still no python.

I wasn't working at IBM itself, but when Dad switched to OS/2 for our
home business, we switched too. That would have been about 1992; we
used OS/2 2.1 briefly, but got properly into things with Warp 3
(Connect, and I can never remember whether it was red-box or blue-box
- we had the one that came with a Windows license for Win-OS/2). Ooh,
we had the most amazing fun with that... we set up, to quote my older
brother, our very own personal World Wide Web! (Not very accurate, but
that was the big buzz-word at the time, and hey, we did have a LAN.)
And over the ensuing years, we got to know which network cards were
the most reliable - mainly the Realtek ones, we had some RTL8029 cards
that went into so many different computers - and if anything went
wrong with drivers or anything, I'd pop the case and stick in one of
my stand-bys. Either that, or we'd go search for the drivers on
Hobbes, and either download 'em onto a floppy disk or LinkWiz them
across - because one of the very first things we'd put onto any
computer was the comms software that uses a special serial-port or
parallel-port cable to transfer files. Immensely useful, until generic
network drivers got better :)

> Did anyone mention that PCs back in that day were toys. And I do mean toys.
> They were slow, they crashed, their graphics sucked...

Oh no! No no no! Graphics didn't suck for everyone. Maybe they did for
you, you with the horrible CGA card plugged into your TV. Maybe they
did for the people who used the default IBM Monochrome card that
didn't do graphics at all. But no, my dad was forward-looking. He got
the best. He got a Hercules Graphics Card, capable of driving the same
screens the IBM Mono would, but giving us the tremendous capability of
720x348 monochrome graphics! It was awesome! Plus, for text colors we
had black, white, bold black, and bold white, and - get this -
underlined! Nobody else got that.

Yes, those were the days.

ChrisA


From invalid at invalid.invalid  Wed Mar  5 10:28:10 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Wed, 5 Mar 2014 15:28:10 +0000 (UTC)
Subject: How security holes happen
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
Message-ID: <lf7fqa$2fv$1@reader1.panix.com>

On 2014-03-04, Marko Rauhamaa <marko at pacujo.net> wrote:
> Ethan Furman <ethan at stoneleaf.us>:
>
>> Okay, that looks totally cool. Maybe I'll finally get a handle on
>> LISP! :)
>
> Lisp is conceptually simpler than Python, but awe-inspiring. One day, it
> will overtake Python, I believe.

Seriously?

LISP had a _30_year_head_start_ yet Python is far ahead and pulling
away...

-- 
Grant Edwards               grant.b.edwards        Yow! I'm continually AMAZED
                                  at               at th'breathtaking effects
                              gmail.com            of WIND EROSION!!


From steve+comp.lang.python at pearwood.info  Wed Mar  5 10:47:40 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 15:47:40 GMT
Subject: How security holes happen
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
Message-ID: <5317471b$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Wed, 05 Mar 2014 00:48:40 +0200, Marko Rauhamaa wrote:

> Ethan Furman <ethan at stoneleaf.us>:
> 
>> Okay, that looks totally cool. Maybe I'll finally get a handle on LISP!
>> :)
> 
> Lisp is conceptually simpler than Python, but awe-inspiring. One day, it
> will overtake Python, I believe.

That day was 25 years ago. According to the long-term TIOBE index, 25 
years ago Lisp was the second most popular programming language in the 
world, behind only C.

http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html

I don't think Lisp has gotten easier, or the average programmer smarter, 
since then. The average programmer has difficulty with while loops, do 
you really think that someday they'll grok lambda calculus? *wink*

Seriously, Lisp is not only one of the oldest high-level languages 
around, being almost as old as Fortran and Cobol, but it was one of the 
biggest languages of the 1970s and even into the 80s. Companies spent 
millions developing, and using, Lisp compilers. There were even Lisp 
machines, actual hardware machines not virtual, where the CPU could 
execute Lisp instructions directly in hardware.

It did not last. It's not that the computer industry hasn't discovered 
Lisp, it is that they discovered it, gave it a solid workout for 20 
years, and then said "Nope, this isn't for us."



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From invalid at invalid.invalid  Wed Mar  5 11:08:00 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Wed, 5 Mar 2014 16:08:00 +0000 (UTC)
Subject: How to create an instance of a python class from C++
References: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>
 <mailman.7780.1393984546.18130.python-list@python.org>
Message-ID: <lf7i50$2fv$2@reader1.panix.com>

On 2014-03-05, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Tue, Mar 4, 2014 at 5:14 PM, Bill <galaxyblue63 at gmail.com> wrote:
>> Hello:
>>
>> I can't figure out how to create an instance
>> of a python class from 'C++':
>>
>> ( I am relatively new to Python so excuse some of the following. )
>>
>> In a .py file I create an ABC and then specialize it:
>
> Why are you creating an ABC?

Because it was the first binary computer that did calculations with
electronic switching elements (gates), and it would be really cool to
have one! The ABC also pioneered the use of capciators as regenerative
storage elements (it's how DRAM still works today).

http://en.wikipedia.org/wiki/Atanasoff%E2%80%93Berry_Computer

It predated ENIAC, and it's clear that some of the features of ENIAC
were inspired by the ABC after John Mauchly visited Iowa State and saw
the ABC.

-- 
Grant Edwards               grant.b.edwards        Yow! I can't decide which
                                  at               WRONG TURN to make first!!
                              gmail.com            I wonder if BOB GUCCIONE
                                                   has these problems!


From harrismh777 at gmail.com  Wed Mar  5 11:37:04 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Wed, 5 Mar 2014 08:37:04 -0800 (PST)
Subject: How security holes happen
In-Reply-To: <5317471b$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <lf22t1$sgh$1@ger.gmane.org>
 <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <5317471b$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <faab1e96-4183-4e11-9526-29cded7bcd96@googlegroups.com>

On Wednesday, March 5, 2014 9:47:40 AM UTC-6, Steven D'Aprano wrote:

> Seriously, Lisp is not only one of the oldest high-level languages 
> around, being almost as old as Fortran and Cobol, but it was one of the  
> biggest languages of the 1970s and even into the 80s. 

Lisp was specified by John McCarthy (of Berkeley, CA) in 1958.  It is the second
oldest computer language behind Fortran, by one year.

There is a resurgence of interest in Lisp today (yes, not so much for common lisp) 
in the Scheme arena. The irony for AI today is that we are finally at the point 
where the technology can finally do what Alonzo Church and Alan Turing dreamed 
about. John McCarthy was *way* ahead of his time too. We are at the point where 
we are wondering again if computer science & technology in software engineering
will ever generate a "thinking" entity---self aware, creative, and of course able to
generate on it's own, "Cogito ergo sum"> 

Lisp/Scheme is awesome. But, if I want to have my little 'ol puter do some real work,
up comes IDLE and out comes a script in a couple of hours that's "awesome"!  
I still play around with gnu emacs and lisp. Its fun, educational, and truly enriching
beyond words. Check out the site, "Lambda the Ultimate" sometime:

http://lambda-the-ultimate.org/

marcus


From alister.ware at ntlworld.com  Wed Mar  5 12:00:19 2014
From: alister.ware at ntlworld.com (Alister)
Date: Wed, 05 Mar 2014 17:00:19 GMT
Subject: How to create an instance of a python class from C++
References: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>
 <mailman.7780.1393984546.18130.python-list@python.org>
 <lf7i50$2fv$2@reader1.panix.com>
Message-ID: <DKIRu.5674$NZ3.5621@fx33.am4>

On Wed, 05 Mar 2014 16:08:00 +0000, Grant Edwards wrote:

> On 2014-03-05, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> On Tue, Mar 4, 2014 at 5:14 PM, Bill <galaxyblue63 at gmail.com> wrote:
>>> Hello:
>>>
>>> I can't figure out how to create an instance of a python class from
>>> 'C++':
>>>
>>> ( I am relatively new to Python so excuse some of the following. )
>>>
>>> In a .py file I create an ABC and then specialize it:
>>
>> Why are you creating an ABC?
> 
> Because it was the first binary computer that did calculations with
> electronic switching elements (gates), and it would be really cool to
> have one! The ABC also pioneered the use of capciators as regenerative
> storage elements (it's how DRAM still works today).
> 
> http://en.wikipedia.org/wiki/Atanasoff%E2%80%93Berry_Computer
> 
> It predated ENIAC, and it's clear that some of the features of ENIAC
> were inspired by the ABC after John Mauchly visited Iowa State and saw
> the ABC.

But it was not programmable

the first programmable electronic computer was 'Colossus'
which was developed during WWII but remained classified by the UK govt 
for many years afterwards 

http://en.wikipedia.org/wiki/Colossus_computer





-- 
You are not dead yet.  But watch for further reports.


From invalid at invalid.invalid  Wed Mar  5 12:14:17 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Wed, 5 Mar 2014 17:14:17 +0000 (UTC)
Subject: How to create an instance of a python class from C++
References: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>
 <mailman.7780.1393984546.18130.python-list@python.org>
 <lf7i50$2fv$2@reader1.panix.com> <DKIRu.5674$NZ3.5621@fx33.am4>
Message-ID: <lf7m19$pk2$1@reader1.panix.com>

On 2014-03-05, Alister <alister.ware at ntlworld.com> wrote:
>>
>>> Why are you creating an ABC?
>> 
>> Because it was the first binary computer that did calculations with
>> electronic switching elements (gates), and it would be really cool to
>> have one! The ABC also pioneered the use of capciators as regenerative
>> storage elements (it's how DRAM still works today).
>> 
>> http://en.wikipedia.org/wiki/Atanasoff%E2%80%93Berry_Computer
>> 
>> It predated ENIAC, and it's clear that some of the features of ENIAC
>> were inspired by the ABC after John Mauchly visited Iowa State and saw
>> the ABC.
>
> But it was not programmable

True.  It had only one program that was hard-wired into it when it was
built as opposed to the external patch-cords and switches that were
used on machines like Colossus and ENIAC to alter the wiring.

> the first programmable electronic computer was 'Colossus' which was
> developed during WWII but remained classified by the UK govt for many
> years afterwards 
>
> http://en.wikipedia.org/wiki/Colossus_computer

-- 
Grant Edwards               grant.b.edwards        Yow! Hmmm ... A hash-singer
                                  at               and a cross-eyed guy were
                              gmail.com            SLEEPING on a deserted
                                                   island, when ...


From rustompmody at gmail.com  Wed Mar  5 12:40:53 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Wed, 5 Mar 2014 09:40:53 -0800 (PST)
Subject: Reference
In-Reply-To: <mailman.7793.1394000462.18130.python-list@python.org>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <mailman.7793.1394000462.18130.python-list@python.org>
Message-ID: <60b9aaba-7991-415d-b3c6-dc18c5539502@googlegroups.com>

On Wednesday, March 5, 2014 11:50:46 AM UTC+5:30, Ben Finney wrote:
> Rustom Mody writes:

> > That python is a hll means that machine reprs are intended to be abstracted
> > away. 'is' fails to do that -- proof of that being the discrepancy between
> > is and ==

> That's your proof? That is a non sequitur. Those two operators are
> *designed to be* different, to compare different things.

> How does the difference between '==' versus 'is', which are designed and
> documented to have different behaviour, lead to your assertion of a
> "leaky abstraction"?

> You have yet to respond to this question asked several times:


If you wish to disagree with me, you are welcome to do so
and I am obliged (up to a point I guess) to assume the disagreement is in 
good faith towards better understanding/usage etc of python.  However...


> > > Can you explain what machine representations are leaked into Python
> > > by the is operator?

> So, what machine represenatation is leaked?

> I'll re-iterate that "memory location of the object" isn't a valid
> response. There is no necessary relation between the memory location of
> the object referenced by "foo" and the return value of 'id(foo)'.

... however you are both disagreeing with me and also saying Ive not given
the answer and further disagreeing with the python standard, which I quote:

Every object has an identity, a type and a value. An object's identity
never changes once it has been created; you may think of it as the
object's address in memory. The 'is' operator compares the identity of
two objects; the id() function returns an integer representing its
identity (currently implemented as its address).

from http://docs.python.org/2/reference/datamodel.html

So when you say
> I'll re-iterate that "memory location of the object" isn't a valid
> response. 

well... all I can say is I dont know what to say :-)


From steve+comp.lang.python at pearwood.info  Wed Mar  5 12:43:02 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 17:43:02 GMT
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7815.1394022463.18130.python-list@python.org>
Message-ID: <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>

On Wed, 05 Mar 2014 12:21:37 +0000, Oscar Benjamin wrote:

> On 5 March 2014 07:52, Steven D'Aprano <steve at pearwood.info> wrote:
>> On Tue, 04 Mar 2014 23:25:37 -0500, Roy Smith wrote:
>>
>>> I stopped paying attention to mathematicians when they tried to
>>> convince me that the sum of all natural numbers is -1/12.
>>
>> I'm pretty sure they did not. Possibly a physicist may have tried to
>> tell you that, but most mathematicians consider physicists to be lousy
>> mathematicians, and the mere fact that they're results seem to actually
>> work in practice is an embarrassment for the entire universe. A
>> mathematician would probably have said that the sum of all natural
>> numbers is divergent and therefore there is no finite answer.
> 
> Why the dig at physicists? 

There is considerable professional rivalry between the branches of 
science. Physicists tend to look at themselves as the paragon of 
scientific "hardness", and look down at mere chemists, who look down at 
biologists. (Which is ironic really, since the actual difficulty in doing 
good science is in the opposite order. Hundreds of years ago, using quite 
primitive techniques, people were able to predict the path of comets 
accurately. I'd like to see them predict the path of a house fly.) 
According to this "greedy reductionist" viewpoint, since all living 
creatures are made up of chemicals, biology is just a subset of 
chemistry, and since chemicals are made up of atoms, chemistry is 
likewise just a subset of physics.

Physics is the fundamental science, at least according to the physicists, 
and Real Soon Now they'll have a Theory Of Everything, something small 
enough to print on a tee-shirt, which will explain everything. At least 
in principle.

Theoretical physicists who work on the deep, fundamental questions of 
Space and Time tend to be the worst for this reductionist streak. They 
have a tendency to think of themselves as elites in an elite field of 
science. Mathematicians, possibly out of professional jealousy, like to 
look down at physics as mere applied maths.

They also get annoyed that physicists often aren't as vigorous with their 
maths as they should be. The controversy over renormalisation in Quantum 
Electrodynamics (QED) is a good example. When you use QED to try to 
calculate the strength of the electron's electric field, you end up 
trying to sum a lot of infinities. Basically, the interaction of the 
electron's charge with it's own electric field gets larger the more 
closely you look. The sum of all those interactions is a divergent 
series. So the physicists basically cancelled out all the infinities, and 
lo and behold just like magic what's left over gives you the right 
answer. Richard Feynman even described it as "hocus-pocus".

The mathematicians *hated* this, and possibly still do, because it looks 
like cheating. It's certainly not vigorous, at least it wasn't back in 
the 1940s. The mathematicians were appalled, and loudly said "You can't 
do that!" and the physicists basically said "Oh yeah, watch us!" and 
ignored them, and then the Universe had the terribly bad manners to side 
with the physicists. QED has turned out to be *astonishingly* accurate, 
the most accurate physical theory of all time. The hocus-pocus worked.


> I think most physicists would be able to tell
> you that the sum of all natural numbers is not -1/12. In fact most
> people with very little background in mathematics can tell you that.

Ah, but there's the rub. People with *very little* background in 
mathematics will tell you that. People with *a very deep and solid* 
background in mathematics will tell you different, particularly if their 
background is complex analysis. (That's *complex numbers*, not 
"complicated" -- although it is complicated too.)


> The argument that the sum of all natural numbers comes to -1/12 is just
> some kind of hoax. I don't think *anyone* seriously believes it.

You would be wrong. I suggest you read the links I gave earlier. Even the 
mathematicians who complain about describing this using the word "equals" 
don't try to dispute the fact that you can identify the sum of natural 
numbers with ?(-1), or that ?(-1) = -1/12. They simply dispute that we 
should describe this association as "equals".

What nobody believes is that the sum of natural numbers is a convergent 
series that sums to -1/12, because it is provably not.

In other words, this is not an argument about the maths. Everyone who 
looks at the maths has to admit that it is sound. It's an argument about 
the words we use to describe this. Is it legitimate to say that the 
infinite sum *equals* -1/12? Or only that the series has the value -1/12? 
Or that we can "associate" (talk about a sloppy, non-vigorous term!) the 
series with -1/12?


>> Well, that is, apart from mathematicians like Euler and Ramanujan. When
>> people like them tell you something, you better pay attention.
> 
> Really? Euler didn't even know about absolutely convergent series (the
> point in question) and would quite happily combine infinite series to
> obtain a formula.

(I note that you avoided criticising Ramanujan's work. Very wise.)

Euler was working on infinite series in the 1700s. There's no doubt that 
his work doesn't meet modern standards of mathematical rigour, but those 
modern standards didn't exist back then. Morris Kline writes of Euler:

    Euler's work lacks rigor, is often ad hoc, and contains blunders, 
    but despite this, his calculations reveal an uncanny ability to 
    judge when his methods might lead to correct results.

http://dept.math.lsa.umich.edu/~krasny/math156_Euler-Kline.pdf

Euler certainly deserves to be in the pantheon of maths demigods, 
possibly the greatest mathematician who ever lived. There is a quip made 
that discoveries in mathematics are usually named after Euler, or the 
first person to discover them after Euler.

Euler also wrote that one should not use the term "sum" to describe the 
total of a divergent series, since that implies regular addition, but 
that one can say that when a divergent series comes from an algebraic 
expression, then the value of the series is the value of the expression 
from which is came. Notice that he carefully avoids using the word 
"equals". (See above URL.)

At one time, Euler summed an infinite series and got -1, from which he 
concluded that -1 was (in some sense) larger than infinity. I don't know 
what justification he gave, but the way I think of it is to take the 
number line from -? to +? and then bend it back upon itself so that there 
is a single infinity, rather like the projective plane only in a single 
dimension. If you start at zero and move towards increasingly large 
numbers, then like Buzz Lightyear you can go to infinity and beyond:

0 -> 1 -> 10 -> 10000 -> ... ? -> ... -10000 -> -10 -> -1 -> 0

In this sense, -1/12 is larger than infinity.

Now of course this is an ad hoc sloppy argument, but I'm not a 
professional mathematician. However I can tell you that it's pretty close 
to what the professional mathematicians and physicists do with negative 
absolute temperatures, and that is rigorous.

http://en.wikipedia.org/wiki/Negative_temperature



[...]
> Personally I think it's reasonable to just say that the sum of the
> natural numbers is infinite rather than messing around with terms like
> undefined, divergent, or existence. There is a clear difference between
> a series (or any limit) that fails to converge  asymptotically and
> another that just goes to +-infinity. The difference is usually also
> relevant to any practical application of this kind of maths.

And this is where you get it exactly backwards. The *practical 
application* comes from physics, where they do exactly what you argue 
against: they associate ?(-1) with the sum of the natural numbers (see, I 
too can avoid the word "equals" too), and *it works*.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From emile at fenx.com  Wed Mar  5 12:46:04 2014
From: emile at fenx.com (Emile van Sebille)
Date: Wed, 05 Mar 2014 09:46:04 -0800
Subject: find and replace string in binary file
In-Reply-To: <687bff67-c486-402d-9f50-82e018c75585@googlegroups.com>
References: <01951a7d-2ab3-4203-a9c5-2f79017a980d@googlegroups.com>
 <lf4jrk$95v$1@ger.gmane.org>
 <CAPTjJmrZPr_QdejVwntYn17LSbuEp_8BsCmR5vfNU9N0PO4QYQ@mail.gmail.com>
 <mailman.7773.1393978398.18130.python-list@python.org>
 <687bff67-c486-402d-9f50-82e018c75585@googlegroups.com>
Message-ID: <lf7nse$3ib$1@ger.gmane.org>

On 3/5/2014 1:59 AM, loial wrote:

> Unfortunately I have to use python 2.6 for this

Did you try it?

Emile





From steve+comp.lang.python at pearwood.info  Wed Mar  5 12:49:32 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 17:49:32 GMT
Subject: Working with the set of real numbers
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <CAHVvXxS+t6e8b_jjyeQcCwLod4_NVfbHjUwPnr5L-TuEzhLwgQ@mail.gmail.com>
 <mailman.7819.1394023826.18130.python-list@python.org>
Message-ID: <531763ab$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Wed, 05 Mar 2014 12:50:06 +0000, Mark Lawrence wrote:

> On 05/03/2014 12:21, Oscar Benjamin wrote:
>>
>> Why the dig at physicists? I think most physicists would be able to
>> tell you that the sum of all natural numbers is not -1/12. In fact most
>> people with very little background in mathematics can tell you that.
>>
>>
> I'll put that one to the test tomorrow morning when the bin men come
> round.

Do you seriously think that garbos (bin men) know more about mathematics 
than mathematicians?


> I fully expect them to dial 999 and ask that the paramedics are
> armed with plenty of sedatives.

You know that rather large piece of machinery in Europe called the Large 
Hadron Collider? The one which is generating some rather extraordinary 
proofs of fundamental physics, such as the Higgs Boson? A lot of that 
physics is based on theory which uses the same logic and mathematics that 
you are mocking.

Laugh away, but the universe behaves as if the sum of the natural numbers 
is -1/12.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Wed Mar  5 13:01:45 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 6 Mar 2014 05:01:45 +1100
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7815.1394022463.18130.python-list@python.org>
 <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmrR3CCTLBV70z+UTrBjbVYGWmOAywS_LrbhtppXH9pU_g@mail.gmail.com>

On Thu, Mar 6, 2014 at 4:43 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Physics is the fundamental science, at least according to the physicists,
> and Real Soon Now they'll have a Theory Of Everything, something small
> enough to print on a tee-shirt, which will explain everything. At least
> in principle.

Everything is, except what isn't.

That's my theory, and I'm sticking to it!

ChrisA


From ckaynor at zindagigames.com  Wed Mar  5 13:03:02 2014
From: ckaynor at zindagigames.com (Chris Kaynor)
Date: Wed, 5 Mar 2014 10:03:02 -0800
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7815.1394022463.18130.python-list@python.org>
 <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALvWhxu7-WpoJUSFSCdO+ToKBDAnP8wDdnSvg05i_xzpzLe=LA@mail.gmail.com>

On Wed, Mar 5, 2014 at 9:43 AM, Steven D'Aprano <
steve+comp.lang.python at pearwood.info> wrote:

> At one time, Euler summed an infinite series and got -1, from which he
> concluded that -1 was (in some sense) larger than infinity. I don't know
> what justification he gave, but the way I think of it is to take the
> number line from -? to +? and then bend it back upon itself so that there
> is a single infinity, rather like the projective plane only in a single
> dimension. If you start at zero and move towards increasingly large
> numbers, then like Buzz Lightyear you can go to infinity and beyond:
>
> 0 -> 1 -> 10 -> 10000 -> ... ? -> ... -10000 -> -10 -> -1 -> 0
>

This makes me think that maybe the universe is using ones or two complement
math (is there a negative zero?)...

Chris
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From python.list at tim.thechases.com  Wed Mar  5 13:12:54 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Wed, 5 Mar 2014 12:12:54 -0600
Subject: Reference
In-Reply-To: <60b9aaba-7991-415d-b3c6-dc18c5539502@googlegroups.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <mailman.7793.1394000462.18130.python-list@python.org>
 <60b9aaba-7991-415d-b3c6-dc18c5539502@googlegroups.com>
Message-ID: <20140305121254.7932731e@bigbox.christie.dr>

On 2014-03-05 09:40, Rustom Mody wrote:
> Every object has an identity, a type and a value. An object's
> identity never changes once it has been created; you may think of
> it as the object's address in memory. The 'is' operator compares
> the identity of two objects; the id() function returns an integer
> representing its identity (currently implemented as its address).
> 
> from http://docs.python.org/2/reference/datamodel.html

Note the "currently", which does not mean "now, always, and forever
for every implementation".

From http://docs.python.org/3/library/functions.html#id

"""
    Return the ?identity? of an object. This is an integer which is
    guaranteed to be unique and constant for this object during its
    lifetime. Two objects with non-overlapping lifetimes may have the
    same id() value.

    CPython implementation detail: This is the address of the object
    in memory.
"""

This is clearly documented as a *CPython implementation detail*.  The
id() function is free to return sequential integers, arbitrary
integers, memory addresses, GUIDs-as-integers, or hashes-as-integers
for some internal representation.

The only thing that matters is (1) that id() returns *some* integer
identifying the object, and (2) the ability to compare id(thing1) with
id(thing2) and see if they are the same or different (assuming thing1
and thing2 share lifetimes during their id() calls), regardless of
what is actually returned.

> So when you say
> > I'll re-iterate that "memory location of the object" isn't a valid
> > response. 
> 
> well... all I can say is I dont know what to say :-)

That you live in a CPython world, unencumbered by experience in other
flavors of language-spec-compliant Python interpreters where id()
returns integers that *aren't* memory addresses?

-tkc






From steve+comp.lang.python at pearwood.info  Wed Mar  5 13:19:25 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 18:19:25 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
Message-ID: <53176aac$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 21:47:21 -0800, Rustom Mody wrote:

> On Wednesday, March 5, 2014 10:36:37 AM UTC+5:30, Steven D'Aprano wrote:
>> On Tue, 04 Mar 2014 19:36:38 -0800, Rustom Mody wrote:
> 
>> > Python's 'is' leaks
>> > the machine abstraction. 'id' does it legitimately (somewhat), 'is'
>> > does it illegitimately
> 
>> and then later in another post:
> 
>> > "is" in python leaks machine representations into the otherwise clean
>> > HLL abstraction in python
> 
>> Rather than respond with incredulity and declare that you have no idea
>> what you are talking about, I'll give you the benefit of the doubt, and
>> accept the possibility that I am wrong, or possibly misunderstanding
>> you.
> 
> Umm...
> I guess my language was sloppy (a bit) A machine is ultimately also an
> abstraction -- What is firmware/microcode? Is it a virtual machine? etc
> Lets leave that however and just take 'machine' as a given.
> 
> Using machines as given, we build reprs for our (programmer's) data
> structures
> 
> So data structures are abstractions that have two 'faces' -- the
> machine-facing and the programmer-facing

What you are describing is normally called the implementation and the 
interface.


> For clarity of expression (and where you perhaps found me sloppy?? not
> sure...) its best to call the machine-face 'a representation' and the
> programmer-face 'an abstraction'

Only if you wish to ignore the standard terminology used by the rest of 
the computing world, and furthermore re-define the term "abstraction".


> Clearly this is a programmer-biased viewpoint. A hardware engineer would
> see things differently. As would the user of the app the programmer
> programs.

This doesn't seem to be relevant.


> Which is why to use the locution "is" without appropriate framing is
> philosopical is a pretension to a 'God's-eye-view'. If you are privy to
> such a viewpoint I'd be interested to know But for the rest of us who
> are not, its good to remember there are only perspectives no absolute
> truth.

And this appears to be meaningless. The best I can come up with is that 
you're concerned about the philosophical implications of stating that 
object x is object y.

Quite frankly, I think that's silly. Such concerns about identity of 
physical entities in the real world are *irrelevant*. You seem to be 
making a category mistake: the word "is" has certain meanings in plain 
English, with associated philosophical problems, therefore the Python 
"is" operator must have exactly the same meanings and problems. But this 
is as silly as thinking that we should be able to use a computer file to 
cut through metal, or that equality between 1+1 and 2 is a question of 
human rights.

The "is" operator has a well-defined meaning in Python. The "axe of my 
grandfather" paradox does not apply to the "is" operator. That definition 
in Python is very simple: the "is" operator returns True if the two 
operands are the same object, and false if they are different objects.

> That python is a hll means that machine reprs are intended to be
> abstracted away. 'is' fails to do that -- proof of that being the
> discrepancy between is and ==

There is no discrepancy between "is" and ==, since they are different 
operators with different semantics. You might as well claim that there is 
a discrepancy between + and * because 5+7 and 5*7 return different 
answers.


>> Can you explain what machine representations are leaked into Python by
>> the is operator?
> 
>> Do you see this as an accident of implementation, a bug that might be
>> fixed, or a misfeature that was deliberately designed?
> 
>> Can you elaborate on why id() is legitimate and "is" is not?
> 
> Let me talk of Lisp which is IMHO more philosophically sane. 

I'd rather you answer the questions I asked rather than change the 
subject to an irrelevance.

[...]
> Decide the viewpoint  -- choose the appropriate equivence predicate No
> claim even remotely to having a clue to metaphysical being that python's
> 'is' implies

There is no metaphysical implication from Python's "is" operator. If the 
operator had precisely the same behaviour, but was called "same", as in:

a same b
=> returns True if a and b are the same object
=> returns False if a and b are not the same object

would you claim there was a metaphysical implication?

How about if it were called "eq", like Lisp uses?



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Wed Mar  5 13:29:18 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 18:29:18 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
Message-ID: <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Tue, 04 Mar 2014 22:03:36 -0800, Rustom Mody wrote:

> On Wednesday, March 5, 2014 10:36:37 AM UTC+5:30, Steven D'Aprano wrote:
>> On Tue, 04 Mar 2014 19:36:38 -0800, Rustom Mody wrote:
> 
>> > Python's 'is' leaks
>> > the machine abstraction. 'id' does it legitimately (somewhat), 'is'
>> > does it illegitimately
> 
> 
>> Can you elaborate on why id() is legitimate and "is" is not?
> 
> Mostly a question of more or less infelicitous English leading to
> philosophical nonsense. [And note I put a 'somewhat']

Well it is certainly true that this discussion has lead to philosophical 
nonsense from one of us.



> I can say "'id' is just 'machine-id' is just address at some low level"

You can say it, but you would be wrong.

I don't know how many times you have to be told. The id() function in 
Python is not defined as returning the address of the object. There is no 
guarantee that objects even have a consistent, stable addresses. Some 
garbage collectors will move objects around. The Python language does not 
claim that the id() function will return the address of objects, it says 
that it will return an abstract ID number that is unique for that object 
while the object exists.


> Its uglier to say "Is is machine-is"
> And before you bring it up, "Jython's id is not machine-id" is putting
> the cart before the horse.
> 
> "Jython is an imitation of Cpython

That's wrong. Jython is not an imitation, it is an independent 
implementation of the same language. Since both CPython and Jython follow 
the specification of the language, both are legitimate Python compilers. 

Both the Jython and CPython id() functions are compliant with the 
language definition. The Jython id() function is better, because it 
doesn't encourage people to mistakenly and foolishly imagine that id() 
equals address.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ben+python at benfinney.id.au  Wed Mar  5 13:33:49 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 06 Mar 2014 05:33:49 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <mailman.7793.1394000462.18130.python-list@python.org>
 <60b9aaba-7991-415d-b3c6-dc18c5539502@googlegroups.com>
Message-ID: <85siqwebqq.fsf@benfinney.id.au>

Rustom Mody <rustompmody at gmail.com> writes:

> On Wednesday, March 5, 2014 11:50:46 AM UTC+5:30, Ben Finney wrote:
> > So, what machine represenatation is leaked?
>
> > I'll re-iterate that "memory location of the object" isn't a valid
> > response. There is no necessary relation between the memory location of
> > the object referenced by "foo" and the return value of 'id(foo)'.
>
> ... however you are both disagreeing with me and also saying Ive not
> given the answer and further disagreeing with the python standard,
> which I quote:
>
> Every object has an identity, a type and a value. An object's identity
> never changes once it has been created; you may think of it as the
> object's address in memory. The 'is' operator compares the identity of
> two objects; the id() function returns an integer representing its
> identity (currently implemented as its address).
>
> from http://docs.python.org/2/reference/datamodel.html

Right. None of which constitutes a leaking abstraction. I'll repeat the
point: the abstraction does not leak if the user of that abstraction has
no need to deal with what lies beneath it.

In other words: A helpful ?you may think of it as the object's address
in memory? does not constitute a leaky abstraction, because it would be
just as correct to say ?you may think of it as a snowflake?.

There is no need for the user of the abstraction ?object identity? to
know anything about the object's location in memory (nor of snowflakes),
nor ever to think about it when using the abstraction. You may, as the
documentation suggests, think of it that way; but you may also think of
it as anything else which agrees with the abstraction.

The clause about ?object's location in memory? is not normative, does
not matter for using the abstraction, and is not part of the definition.
It literally does not matter for the purpose of using the abstraction,
so there's no leak.

In fact, in the current Python documentation the description has changed:

    Every object has an identity, a type and a value. An object?s
    identity never changes once it has been created; you may think of it
    as the object?s address in memory. The ?is? operator compares the
    identity of two objects; the id() function returns an integer
    representing its identity.

    CPython implementation detail: For CPython, id(x) is the memory
    address where x is stored.

    <URL:http://docs.python.org/3/reference/datamodel.html>

So it's now even clearer that ?memory address where the object is
stored? is *not* part of the abstraction, is *not* guaranteed to be what
?id(foo)? returns, and is an implementation detail of one particular
implementation, that can be ignored.

The abstraction ?object identity? behaves exactly as the documentation
says it does, in the absence of any ?object address in memory? concept,
and this is not undermined by suggestions that the reader may already
have a concept in mind which can help them to imagine the abstraction.

> So when you say
> > I'll re-iterate that "memory location of the object" isn't a valid
> > response. 
>
> well... all I can say is I dont know what to say :-)

I'd encourage you to read the documentation for comprehension. Not every
word in a discussion of a concept must be normative.

I'd also encourage you to report a bug, suggesting a documentation
improvement if you have been misled by (the latest version of) the
language reference.

-- 
 \        ?Of course, everybody says they're for peace. Hitler was for |
  `\      peace. Everybody is for peace. The question is: what kind of |
_o__)                                peace?? ?Noam Chomsky, 1984-05-14 |
Ben Finney



From steve+comp.lang.python at pearwood.info  Wed Mar  5 13:42:46 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 05 Mar 2014 18:42:46 GMT
Subject: How security holes happen
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <qsrch9lgi81sd33hu8kag5s6cvhhj637g9@4ax.com>
 <mailman.7823.1394029216.18130.python-list@python.org>
 <87zjl47l18.fsf@elektro.pacujo.net>
Message-ID: <53177025$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Wed, 05 Mar 2014 16:54:59 +0200, Marko Rauhamaa wrote:

> I don't think Lisp was really originally designed.

The history of Lisp is described here in detail:

http://www-formal.stanford.edu/jmc/history/lisp/lisp.html

Like all complex systems, it did not appear fully-formed in a flash of 
inspiration. It was both designed and evolved through experimentation. 
That process of *trying things* and keeping those that work is usually 
called "design".


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Wed Mar  5 14:00:10 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 6 Mar 2014 06:00:10 +1100
Subject: How security holes happen
In-Reply-To: <53177025$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <20140303221926.GA57537@cskk.homeip.net>
 <CAPTjJmpk+5hRUS7Xp1C73Hypc5qhm4HXZwMTJOdqfx_8JjfKSA@mail.gmail.com>
 <mailman.7678.1393887688.18130.python-list@python.org>
 <99ca7396-bcb8-49f9-b486-56ae88aa00e5@googlegroups.com>
 <CAPTjJmpedFgRigss0S2rM-v3dDR++ivy88Xs_ZMEyXpX2b1wdQ@mail.gmail.com>
 <CANc-5Uzw703CBdWQOntoPDMtj6BaxrHNPyVC226ctVxhXgFO1Q@mail.gmail.com>
 <lf5e4d$lfm$1@ger.gmane.org>
 <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <qsrch9lgi81sd33hu8kag5s6cvhhj637g9@4ax.com>
 <mailman.7823.1394029216.18130.python-list@python.org>
 <87zjl47l18.fsf@elektro.pacujo.net>
 <53177025$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmoD21+JFDBNn0Ypqc_MZ0c-Dyrtp0CWpyKrXs2rOpHoCA@mail.gmail.com>

On Thu, Mar 6, 2014 at 5:42 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Wed, 05 Mar 2014 16:54:59 +0200, Marko Rauhamaa wrote:
>
>> I don't think Lisp was really originally designed.
>
> The history of Lisp is described here in detail:
>
> http://www-formal.stanford.edu/jmc/history/lisp/lisp.html
>
> Like all complex systems, it did not appear fully-formed in a flash of
> inspiration. It was both designed and evolved through experimentation.
> That process of *trying things* and keeping those that work is usually
> called "design".

There's a difference between iterative design of that nature and
initial design. An initial clean design is a good basis for further
iterative design; a messy initial design means backward compatibility
shackles you. "Originally designed" is different from "constantly
worked on".

But Lisp has enough variants that the backward compat issue isn't as
major. There's no specific need for Scheme to maintain every mistake
of Common Lisp, or Clojure to support everything that elisp does.

ChrisA


From invalid at invalid.invalid  Wed Mar  5 14:13:01 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Wed, 5 Mar 2014 19:13:01 +0000 (UTC)
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7815.1394022463.18130.python-list@python.org>
 <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7828.1394043041.18130.python-list@python.org>
Message-ID: <lf7svs$df2$1@reader1.panix.com>

On 2014-03-05, Chris Kaynor <ckaynor at zindagigames.com> wrote:
> On Wed, Mar 5, 2014 at 9:43 AM, Steven D'Aprano <
> steve+comp.lang.python at pearwood.info> wrote:
>
>> At one time, Euler summed an infinite series and got -1, from which he
>> concluded that -1 was (in some sense) larger than infinity. I don't know
>> what justification he gave, but the way I think of it is to take the
>> number line from -? to +? and then bend it back upon itself so that there
>> is a single infinity, rather like the projective plane only in a single
>> dimension. If you start at zero and move towards increasingly large
>> numbers, then like Buzz Lightyear you can go to infinity and beyond:
>>
>> 0 -> 1 -> 10 -> 10000 -> ... ? -> ... -10000 -> -10 -> -1 -> 0
>>
>
> This makes me think that maybe the universe is using ones or two complement
> math (is there a negative zero?)...

If the Universe (like most all Python implementations) is using
IEEE-754 floating point, there is.

-- 
Grant Edwards               grant.b.edwards        Yow! This PIZZA symbolizes
                                  at               my COMPLETE EMOTIONAL
                              gmail.com            RECOVERY!!


From marko at pacujo.net  Wed Mar  5 15:23:46 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 22:23:46 +0200
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <53176aac$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87r46g75t9.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> There is no metaphysical implication from Python's "is" operator. If the 
> operator had precisely the same behaviour, but was called "same", as in:
>
> a same b
> => returns True if a and b are the same object
> => returns False if a and b are not the same object
>
> would you claim there was a metaphysical implication?

I would. You are not defining anything because you are not explaining
what "same object" means.

Set theory obeys the so-called extensionality principle: if two objects
are indistinguishable in every way, they are one and the same object.
Fermions in particle physics are the same way: if two fermions' quantum
states coincide, they are one and the same particle.

Now, that's not true for Pythons "bosonic" objects. You can have two
objects that are identical except they are not the same.

There are (at least) two ways to break the circularity between "is" and
"same-objectness:"

  1. Give a real or hypothetical reference implementation and state that
     any other implementation that produces same (or similar enough)
     outcomes is valid. ("Each object is allocated with the malloc(3)
     function call. The identity of an object is the value returned by
     malloc(3).")

  2. Give formal axioms that characterize any valid implementation.
     ("After x = y, x is y" plus a couple of dozen more formal
     stipulations.)


As for teaching the concept in practice, both of the above approaches
are probably bad. Take abstract algebra. You don't start teaching a
first-grader about groups and rings and work your way down to
arithmetics. Rather, you start with counting, move on to arithmetics,
bring in vectors and maybe Rubik's Cube and finally try to get the
students to understand the general, abstract idea behind it all.

Analogously, it may be necessary to teach the "children" first the
theory of linear memory, then variables and arrays, then pointers and
singly-linked lists. Once these concrete ideas have been understood, the
principles behind Python and other higher-level programming languages
can be learned.

> How about if it were called "eq", like Lisp uses?

You are correct. Lisp suffers from the same problem. The underlying
reference machine is simpler to present, though, as there are no classes
or methods. There are only memory cells and a handful of data types
(number, cons, symbol, string or nil). You really get a feel of a
physical steam engine.

Ten years ago a whole generation of programmers was raised who knew
nothing of computing except Java. I wonder how difficult it was for them
to get objects, references and identity.


Marko


From invalid at invalid.invalid  Wed Mar  5 15:31:27 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Wed, 5 Mar 2014 20:31:27 +0000 (UTC)
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <53176aac$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87r46g75t9.fsf@elektro.pacujo.net>
Message-ID: <lf81iu$rti$1@reader1.panix.com>

On 2014-03-05, Marko Rauhamaa <marko at pacujo.net> wrote:

> Set theory obeys the so-called extensionality principle: if two
> objects are indistinguishable in every way, they are one and the same
> object. Fermions in particle physics are the same way: if two
> fermions' quantum states coincide, they are one and the same
> particle.
>
> Now, that's not true for Pythons "bosonic" objects. You can have two
> objects that are identical except they are not the same.

Wrong.  If the two objects are not the same, then they will have
different ID values.  If the ID values are the same, then you've only
got one object.

Two different objects are always distinguishable in Python because
they will always have different ID values.

> There are (at least) two ways to break the circularity between "is" and
> "same-objectness:"

I'm sorry, what problem are you trying to solve?

-- 
Grant Edwards               grant.b.edwards        Yow! I'm definitely not
                                  at               in Omaha!
                              gmail.com            


From marko at pacujo.net  Wed Mar  5 15:34:31 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 22:34:31 +0200
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87mwh475bc.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> The id() function in Python is not defined as returning the address of
> the object.

It might as well. If I said id() returns the address of the object in
the Python VM's virtual address space, you couldn't call my bluff.

Say id() returned the intantiation sequence number. I could say, the
infinite linear memory starts from address 0 and each object occupies a
single memory slot.

> That's wrong. Jython is not an imitation, it is an independent
> implementation of the same language. Since both CPython and Jython
> follow the specification of the language, both are legitimate Python
> compilers.
>
> Both the Jython and CPython id() functions are compliant with the
> language definition. The Jython id() function is better, because it
> doesn't encourage people to mistakenly and foolishly imagine that id()
> equals address.

I agree with everything (how could I not) except the foolishness part:
what bad consequence is there for "imagining" that id() equals address?
If id() offers the only glimpse into the "memory," we can say that id()
*is* the address.


Marko


From prologic at shortcircuit.net.au  Wed Mar  5 15:47:20 2014
From: prologic at shortcircuit.net.au (James Mills)
Date: Thu, 6 Mar 2014 06:47:20 +1000
Subject: ANN: Python Job Board - Call for volunteers
In-Reply-To: <530F52DB.9030708@python.org>
References: <530F52DB.9030708@python.org>
Message-ID: <CALGqR9JAPZo9VvubhDWo3c5VXPm4iuz8rBkFVqobqxUbAwNjNg@mail.gmail.com>

I'd like to volunteer!
On Mar 5, 2014 7:13 PM, "M.-A. Lemburg" <mal at python.org> wrote:

> [Please help spread the word by forwarding to other relevant mailing lists,
>  user groups, etc. world-wide; thanks :-)]
>
> Dear Python Community,
>
> for many years, the Python Job board (
> http://legacy.python.org/community/jobs/)
> was run by volunteers - most of the time by just one volunteer at a
> time until they moved on to spend their time on other things.
> We've now reached such a point again.
>
> In these years, the volume on the job board has significantly
> increased, as it got more and more popular. It is now at around
> 2-5 postings per day and most of those positions get filled quickly
> - which is an indication of how useful this service is to the
> Python community.
>
> To scale up and revive the job board, the PSF would now like to setup
> a *team of volunteers* to run the job board and this is our call for
> help.
>
>
> How does the job board work ?
> -----------------------------
>
> At the moment, the job board is maintained on the legacy site
> (http://legacy.python.org/community/jobs/), but since we've
> launched our brand new website (http://www.python.org/), we'd like
> to move the job board over to that site.
>
> Instead of the repository based approach used on the old site,
> the new site has database support to aid in more easily processing
> and filing job listings.
>
> There's a job board mailing list which helps coordinate the
> task of reviewing and filing job offers. Currently, all job
> submissions get sent to this mailing list, but with the job board
> app, the submission process can be moved over to the website's
> database.
>
>
> What does it take to run the job board ?
> ----------------------------------------
>
> You have to review the job postings, request changes if they are too
> long, don't clearly state the need for Python skills, or have quality
> issues.
>
> After review, the job board app will then allow posting the jobs
> on the website by simply setting the status to published.
>
> Communication with the submitters is usually done by email
> and via the mailing list, so all team members can see the
> communication and help out if necessary.
>
> Please note: This is just a high level overview. The details
> need to be hashed out by the new team.
>
>
> Does the job board app work already ?
> -------------------------------------
>
> It does, but is disabled at the moment due to lack of volunteers.
>
> Since the site just launched there may also well be some issues
> with the job board app.
>
> On the positive side there's a lot happening around the site at the
> moment, so if you have change requests, these will usually be
> implemented quickly - or you can jump in, hack on the
> job board app and submit a pull request yourself:
>
> https://github.com/python/pythondotorg/tree/master/jobs
>
> These are exciting times and this is your chance to make a
> difference !
>
>
> Ok, I like new challenges - where do I sign up ?
> ------------------------------------------------
>
> Great :-) Please write to jobs at python.org
>
>
> I have a question...
> --------------------
>
> If you have questions, you can write me or the PSF board
> at psf at python.org.
>
>
> Many thanks,
> --
> Marc-Andre Lemburg
> Director
> Python Software Foundation
> http://www.python.org/psf/
> --
> https://mail.python.org/mailman/listinfo/python-announce-list
>
>         Support the Python Software Foundation:
>         http://www.python.org/psf/donations/
>
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From marko at pacujo.net  Wed Mar  5 15:46:29 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 22:46:29 +0200
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <53176aac$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87r46g75t9.fsf@elektro.pacujo.net> <lf81iu$rti$1@reader1.panix.com>
Message-ID: <87iors74re.fsf@elektro.pacujo.net>

Grant Edwards <invalid at invalid.invalid>:

> Wrong. If the two objects are not the same, then they will have
> different ID values. If the ID values are the same, then you've only
> got one object.

Ok, that circularity again.

Say I implement Python. Say I returned a random number for id(), how
would that violate the language spec?

It would violate the spec. But there would have to be a paragraph in the
specification that was violated or a reference test case that failed.

For example, this test would demonstrate obviously invalid behavior:

   >>> print(id(x))
   129
   >>> print(id(x))
   201

> I'm sorry, what problem are you trying to solve?

I think the discussion spawned from the problem of teaching programming
students the right idea of values and objects. A teacher would like to
bring in advanced concepts last, but Python seems to force you to get
them at the very beginning.


Marko


From ben+python at benfinney.id.au  Wed Mar  5 16:01:21 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 06 Mar 2014 08:01:21 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
Message-ID: <85iorse4wu.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
> > Both the Jython and CPython id() functions are compliant with the
> > language definition. The Jython id() function is better, because it
> > doesn't encourage people to mistakenly and foolishly imagine that
> > id() equals address.
>
> I agree with everything (how could I not) except the foolishness part:
> what bad consequence is there for "imagining" that id() equals
> address?

It is a false inference.

A reference-compliant implementation can contradict your inference (by
returning an object identity that is *not* the object's memory address).
Any code you've written based on that false inference will break.

The fault will be yours, for inferring an assertion that isn't implied
by the definition.

-- 
 \       ?The surest way to corrupt a youth is to instruct him to hold |
  `\       in higher esteem those who think alike than those who think |
_o__)             differently.? ?Friedrich Nietzsche, _The Dawn_, 1881 |
Ben Finney



From ben+python at benfinney.id.au  Wed Mar  5 16:07:25 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 06 Mar 2014 08:07:25 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <53176aac$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87r46g75t9.fsf@elektro.pacujo.net> <lf81iu$rti$1@reader1.panix.com>
 <87iors74re.fsf@elektro.pacujo.net>
Message-ID: <85eh2ge4mq.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Say I implement Python. Say I returned a random number for id(), how
> would that violate the language spec?

You could do that, certainly. So long as that randomly-chosen integer
was always the same for every object, and never the same for any other
concurrently-existing object, it can just as well be assigned randomly.

If you're saying that your implementation of ?id(foo)? would return a
*different* integer when called at different times for the same object,
then yes, that violates the specification for that function.

> It would violate the spec. But there would have to be a paragraph in
> the specification that was violated or a reference test case that
> failed.

Yes. It would violate this paragraph:

    Every object has an identity, a type and a value. An object?s
    identity never changes once it has been created [?] the id()
    function returns an integer representing its identity.

    <URL:http://docs.python.org/3/reference/datamodel.html>

Again, I ask you to read these documents for comprehension.

> For example, this test would demonstrate obviously invalid behavior:
>
>    >>> print(id(x))
>    129
>    >>> print(id(x))
>    201

Yes. That violates the paragraph above, and so that implementation is
not compliant with the Python language reference.

-- 
 \       ?I watched the Indy 500, and I was thinking that if they left |
  `\         earlier they wouldn't have to go so fast.? ?Steven Wright |
_o__)                                                                  |
Ben Finney



From ben+python at benfinney.id.au  Wed Mar  5 16:10:32 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 06 Mar 2014 08:10:32 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <53176aac$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87r46g75t9.fsf@elektro.pacujo.net> <lf81iu$rti$1@reader1.panix.com>
 <87iors74re.fsf@elektro.pacujo.net>
Message-ID: <85a9d4e4hj.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Grant Edwards <invalid at invalid.invalid>:
>
> > Wrong. If the two objects are not the same, then they will have
> > different ID values. If the ID values are the same, then you've only
> > got one object.
>
> Ok, that circularity again.

Yes, it's circular. In an abstract system like a programming language,
where the definition only needs to describe behaviour of that system,
what is your objection to circularity of definition?

A great many abstract systems designed by humans are defined in terms
that are ultimately circular. This does not in any way hinder them from
being useful definitions of useful systems.

-- 
 \        ?All opinions are not equal. Some are a very great deal more |
  `\    robust, sophisticated and well supported in logic and argument |
_o__)                                     than others.? ?Douglas Adams |
Ben Finney



From marko at pacujo.net  Wed Mar  5 16:14:44 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 23:14:44 +0200
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
Message-ID: <87bnxk73gb.fsf@elektro.pacujo.net>

Ben Finney <ben+python at benfinney.id.au>:

> A reference-compliant implementation can contradict your inference (by
> returning an object identity that is *not* the object's memory
> address). Any code you've written based on that false inference will
> break.
>
> The fault will be yours, for inferring an assertion that isn't implied
> by the definition.

Show me a few lines of Python that demonstrate the error of the false
inference, please.

When I talk about an object's memory address, I'm not referring to what
might be revealed by gdb, for example. That is, I'm not talking about
the process's virtual address space, nor am I talking about the physical
address on the address bus. I can simply define that the object's memory
address is whatever id() returns.


Marko


From oscar.j.benjamin at gmail.com  Wed Mar  5 16:22:15 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Wed, 5 Mar 2014 21:22:15 +0000
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7815.1394022463.18130.python-list@python.org>
 <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAHVvXxTKC87XFsXJfpY2pLpJe7GdFNeSy9FqOUAHgDyAhm=Hyw@mail.gmail.com>

On 5 March 2014 17:43, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Wed, 05 Mar 2014 12:21:37 +0000, Oscar Benjamin wrote:
>>
>> The argument that the sum of all natural numbers comes to -1/12 is just
>> some kind of hoax. I don't think *anyone* seriously believes it.
>
> You would be wrong. I suggest you read the links I gave earlier. Even the
> mathematicians who complain about describing this using the word "equals"
> don't try to dispute the fact that you can identify the sum of natural
> numbers with ?(-1), or that ?(-1) = -1/12. They simply dispute that we
> should describe this association as "equals".
>
> What nobody believes is that the sum of natural numbers is a convergent
> series that sums to -1/12, because it is provably not.
>
> In other words, this is not an argument about the maths. Everyone who
> looks at the maths has to admit that it is sound. It's an argument about
> the words we use to describe this. Is it legitimate to say that the
> infinite sum *equals* -1/12? Or only that the series has the value -1/12?
> Or that we can "associate" (talk about a sloppy, non-vigorous term!) the
> series with -1/12?

This is the point. You can "identify" numbers with many different
things. It does not mean to say that the thing is equal to that
number. I can associate the number 2 with my bike since it has 2
wheels. That doesn't mean that the bike is equal to 2.

So the problem with saying that "the sum of the natural numbers equals
-1/12" is precisely as you say with the word "equals" because they're
not equal!

If you restate the conclusion in more accurate (but technical and less
accessible) way that "the analytic continuation of a related set of
convergent series has the value -1/12 at the value that would
correspond to this divergent series" then it becomes less mysterious.
Do I really have to associate the finite negative value found in the
analytic continuation with the sum of the series that is provably
greater than any finite number?

<snip>
>
> At one time, Euler summed an infinite series and got -1, from which he
> concluded that -1 was (in some sense) larger than infinity. I don't know
> what justification he gave, but the way I think of it is to take the
> number line from -? to +? and then bend it back upon itself so that there
> is a single infinity, rather like the projective plane only in a single
> dimension. If you start at zero and move towards increasingly large
> numbers, then like Buzz Lightyear you can go to infinity and beyond:
>
> 0 -> 1 -> 10 -> 10000 -> ... ? -> ... -10000 -> -10 -> -1 -> 0
>
> In this sense, -1/12 is larger than infinity.

There are many examples that appear to show wrapping round from
+infinity to -infinity e.g. the tan function. The thing is that it is
not really "physical" (or meaningful in any direct sense).

So for example I might consider the forces on a particle, apply
Newton's 2nd law and arrive at a differential equation for the
acceleration of the particle, solve the equation and find that the
position of the particle at time t is given by tan(t). This would seem
to imply that as t increases toward pi/2 the particle heads off
infinity miles West but at the exact time pi/2 it wraps around to
reappear at infinity miles East and starts heading back toward its
starting point. The truth is less interesting: the solution tan(t)
becomes invalid at pi/2 and mathematics can tell us nothing about what
happens after that even if all the physics we used was exactly true.

> Now of course this is an ad hoc sloppy argument, but I'm not a
> professional mathematician. However I can tell you that it's pretty close
> to what the professional mathematicians and physicists do with negative
> absolute temperatures, and that is rigorous.
>
> http://en.wikipedia.org/wiki/Negative_temperature

The key point from that page is the sentence "A definition of
temperature can be based on the relationship...".  It is clear that
temperature is a theoretical abstraction. We have intuitive
understandings of what it means but in order for the current body of
thermodynamic theory to be consistent it is necessary to sometimes
give negative values to the temperature. There's nothing unintuitive
about negative temperatures if you understand the usual thermodynamic
definitions of "temperature".

>> Personally I think it's reasonable to just say that the sum of the
>> natural numbers is infinite rather than messing around with terms like
>> undefined, divergent, or existence. There is a clear difference between
>> a series (or any limit) that fails to converge  asymptotically and
>> another that just goes to +-infinity. The difference is usually also
>> relevant to any practical application of this kind of maths.
>
> And this is where you get it exactly backwards. The *practical
> application* comes from physics, where they do exactly what you argue
> against: they associate ?(-1) with the sum of the natural numbers (see, I
> too can avoid the word "equals" too), and *it works*.

I don't know all the details of what they do there and whether or not
there's a better way of doing it or perhaps a better way of thinking
about the mathematical procedures they apply. (I'm assuming you're
talking about the Casimir effect here).

Let's use a more down to earth example though. Every day from now I'll
give you N pounds where N is the number of days from today. so
tomorrow I'll give you 1 pound, the next day 2 pounds and so on. If
this continues for an infinitely long time then you will have been
given an infinite amount of money. If you phrase the question like
this then I think the professional mathematicians you're referring to
will agree that the sum is infinite.

(It's possible that the money I said I'd send will not materialise. If
you receive a bill for 8 pence you'll know that I was wrong which
should console you for the missing infinite amounts of money).


Oscar


From rosuav at gmail.com  Wed Mar  5 16:26:22 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 6 Mar 2014 08:26:22 +1100
Subject: Reference
In-Reply-To: <87bnxk73gb.fsf@elektro.pacujo.net>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
 <87bnxk73gb.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpDfoEYgbpchz=kWj1p03yobzW9WXwYHtH+VzMh+C+rfg@mail.gmail.com>

On Thu, Mar 6, 2014 at 8:14 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> When I talk about an object's memory address, I'm not referring to what
> might be revealed by gdb, for example. That is, I'm not talking about
> the process's virtual address space, nor am I talking about the physical
> address on the address bus. I can simply define that the object's memory
> address is whatever id() returns.

Where's the complaints about circularity now? You're saying "But of
course id() returns the address, as long as we define the address as
'whatever id() returns'.". Unimpeachably logical and utterly
unhelpful.

ChrisA


From python.list at tim.thechases.com  Wed Mar  5 16:33:53 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Wed, 5 Mar 2014 15:33:53 -0600
Subject: Reference
In-Reply-To: <87bnxk73gb.fsf@elektro.pacujo.net>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
 <87bnxk73gb.fsf@elektro.pacujo.net>
Message-ID: <20140305153353.4b948c31@bigbox.christie.dr>

On 2014-03-05 23:14, Marko Rauhamaa wrote:
> When I talk about an object's memory address, I'm not referring to
> what might be revealed by gdb, for example. That is, I'm not
> talking about the process's virtual address space, nor am I talking
> about the physical address on the address bus. I can simply define
> that the object's memory address is whatever id() returns.

Let me translate what the rest of the group hears:

"""
When I talk about an object's memory address, I'm not referring to
*what every other computer scientist/professional means by "memory
address" rather I can simply make up my own definition for "memory
address" so that it means something that proves my point.*
"""

It's perfectly valid for the definition of id() to return negative
numbers, yet in just about every situation (both hypothetical CS
worlds and out in the real world), a memory-address is defined as an
unsigned number.

-tkc




From breamoreboy at yahoo.co.uk  Wed Mar  5 16:34:40 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 05 Mar 2014 21:34:40 +0000
Subject: Reference
In-Reply-To: <87iors74re.fsf@elektro.pacujo.net>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <53176aac$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87r46g75t9.fsf@elektro.pacujo.net> <lf81iu$rti$1@reader1.panix.com>
 <87iors74re.fsf@elektro.pacujo.net>
Message-ID: <lf859a$bae$1@ger.gmane.org>

On 05/03/2014 20:46, Marko Rauhamaa wrote:
>
> I think the discussion spawned from the problem of teaching programming
> students the right idea of values and objects. A teacher would like to
> bring in advanced concepts last, but Python seems to force you to get
> them at the very beginning.
>

Nonsense, people starting out with Python have stated how easy it is to 
just start writing Python code.  This would obviously not be possible if 
advanced concepts had to be learned up front.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ben+python at benfinney.id.au  Wed Mar  5 16:37:19 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 06 Mar 2014 08:37:19 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
 <87bnxk73gb.fsf@elektro.pacujo.net>
Message-ID: <851tyge38w.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Ben Finney <ben+python at benfinney.id.au>:
>
> > A reference-compliant implementation can contradict your inference (by
> > returning an object identity that is *not* the object's memory
> > address). Any code you've written based on that false inference will
> > break.
> >
> > The fault will be yours, for inferring an assertion that isn't implied
> > by the definition.
>
> Show me a few lines of Python that demonstrate the error of the false
> inference, please.

It need not be Python; it could be an extension library to which you
pass the ?id(foo)? result, on the false assumption that it must be a
memory location.

Besides which, it is *you* that declares this abstraction to be leaky.
If you're unable to show how that's the case, I rest on the null
hypothesis: your assertion is untrue.

> When I talk about an object's memory address, I'm not referring to
> what might be revealed by gdb, for example. That is, I'm not talking
> about the process's virtual address space, nor am I talking about the
> physical address on the address bus. I can simply define that the
> object's memory address is whatever id() returns.

Then this does not count as a leaky abstraction. All you're saying is
that the ?id(foo)? result is a representation of the object identity,
which is entirely at the level of the abstraction. Nothing is leaked.

-- 
 \      ?God forbid that any book should be banned. The practice is as |
  `\                  indefensible as infanticide.? ?Dame Rebecca West |
_o__)                                                                  |
Ben Finney



From keplero1 at hotmail.com  Wed Mar  5 16:41:10 2014
From: keplero1 at hotmail.com (Luciano Trespidi)
Date: Wed, 5 Mar 2014 22:41:10 +0100
Subject: Program Python
Message-ID: <DUB406-EAS5040C6D80CD82DA8BF4F2094890@phx.gbl>

I'm very grateful if anyone can helpme to find a good program to develop in python lenguage.
Thanks


Inviato da:
Ernesto Luciano Trespidi
Email: keplero1 at hotmail.com
Tel.  3299255463

From breamoreboy at yahoo.co.uk  Wed Mar  5 16:46:29 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 05 Mar 2014 21:46:29 +0000
Subject: Reference
In-Reply-To: <20140305153353.4b948c31@bigbox.christie.dr>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
 <87bnxk73gb.fsf@elektro.pacujo.net>
 <20140305153353.4b948c31@bigbox.christie.dr>
Message-ID: <lf85vf$jf8$1@ger.gmane.org>

On 05/03/2014 21:33, Tim Chase wrote:
> On 2014-03-05 23:14, Marko Rauhamaa wrote:
>> When I talk about an object's memory address, I'm not referring to
>> what might be revealed by gdb, for example. That is, I'm not
>> talking about the process's virtual address space, nor am I talking
>> about the physical address on the address bus. I can simply define
>> that the object's memory address is whatever id() returns.
>
> Let me translate what the rest of the group hears:
>
> """
> When I talk about an object's memory address, I'm not referring to
> *what every other computer scientist/professional means by "memory
> address" rather I can simply make up my own definition for "memory
> address" so that it means something that proves my point.*
> """
>
> It's perfectly valid for the definition of id() to return negative
> numbers, yet in just about every situation (both hypothetical CS
> worlds and out in the real world), a memory-address is defined as an
> unsigned number.
>
> -tkc
>
>

I actually hear the spam song, except s/spam/troll/

Didn't we learn anything from the sadly still ongoing saga of our 
resident unicode expert? :(
-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ben+python at benfinney.id.au  Wed Mar  5 16:53:05 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 06 Mar 2014 08:53:05 +1100
Subject: Program Python
References: <DUB406-EAS5040C6D80CD82DA8BF4F2094890@phx.gbl>
Message-ID: <85wqg8cny6.fsf@benfinney.id.au>

Luciano Trespidi <keplero1 at hotmail.com> writes:

> I'm very grateful if anyone can helpme to find a good program to develop in python lenguage.
> Thanks

The best program to use for developing in the Python language is the
Python interpreter :-)

Beyond which, you may be interested in the Python community's ?tutor?
forum <URL:https://mail.python.org/mailman/listinfo/tutor>, a great
resource for asking questions about the basics of Python.

-- 
 \       ?The most common of all follies is to believe passionately in |
  `\    the palpably not true. It is the chief occupation of mankind.? |
_o__)                                                ?Henry L. Mencken |
Ben Finney



From marko at pacujo.net  Wed Mar  5 16:50:26 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 05 Mar 2014 23:50:26 +0200
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
 <87bnxk73gb.fsf@elektro.pacujo.net>
 <mailman.7837.1394054791.18130.python-list@python.org>
Message-ID: <874n3c71st.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Thu, Mar 6, 2014 at 8:14 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> When I talk about an object's memory address, I'm not referring to
>> what might be revealed by gdb, for example. That is, I'm not talking
>> about the process's virtual address space, nor am I talking about the
>> physical address on the address bus. I can simply define that the
>> object's memory address is whatever id() returns.
>
> Where's the complaints about circularity now? You're saying "But of
> course id() returns the address, as long as we define the address as
> 'whatever id() returns'.". Unimpeachably logical and utterly
> unhelpful.

Main thing, no harm done.

The memory address is neither right nor wrong. It's completely
irrelevant since it doesn't occupy a place in Python's data model.


Marko


From gheskett at wdtv.com  Wed Mar  5 17:21:03 2014
From: gheskett at wdtv.com (Gene Heskett)
Date: Wed, 5 Mar 2014 17:21:03 -0500
Subject: How to create an instance of a python class from C++
In-Reply-To: <lf7m19$pk2$1@reader1.panix.com>
References: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>
 <DKIRu.5674$NZ3.5621@fx33.am4> <lf7m19$pk2$1@reader1.panix.com>
Message-ID: <201403051721.03598.gheskett@wdtv.com>

On Wednesday 05 March 2014 17:09:53 Grant Edwards did opine:

> On 2014-03-05, Alister <alister.ware at ntlworld.com> wrote:
> >>> Why are you creating an ABC?
> >> 
> >> Because it was the first binary computer that did calculations with
> >> electronic switching elements (gates), and it would be really cool to
> >> have one! The ABC also pioneered the use of capciators as
> >> regenerative storage elements (it's how DRAM still works today).
> >> 
> >> http://en.wikipedia.org/wiki/Atanasoff%E2%80%93Berry_Computer
> >> 
> >> It predated ENIAC, and it's clear that some of the features of ENIAC
> >> were inspired by the ABC after John Mauchly visited Iowa State and
> >> saw the ABC.
> > 
> > But it was not programmable
> 
> True.  It had only one program that was hard-wired into it when it was
> built as opposed to the external patch-cords and switches that were
> used on machines like Colossus and ENIAC to alter the wiring.
> 
> > the first programmable electronic computer was 'Colossus' which was
> > developed during WWII but remained classified by the UK govt for many
> > years afterwards
> > 
> > http://en.wikipedia.org/wiki/Colossus_computer

What machine was it that had about 12,000 12AU7 vacuum tubes in it for 
logic?  They had one of those, adapted to read the output of a bed of 
photocells installed in a Harris sheet fed press on the SUI campus in the 
later 1950's.  I saw it running once, grading the test score sheets from 
the Iowa Tests that were being used in lieu of the high price per seat S-B 
IQ test in the Iowa schools.  It was IIRC a somewhat difficult test when 
they threw it at me in the 7th grade a decade earlier, they claimed the 
test score were interchangeable with the S-B scores, but I somehow managed 
a 147 on it at the time.

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

NOTICE: Will pay 100 USD for an HP-4815A defective but
complete probe assembly.



From larry.martell at gmail.com  Wed Mar  5 17:27:31 2014
From: larry.martell at gmail.com (Larry Martell)
Date: Wed, 5 Mar 2014 17:27:31 -0500
Subject: script uses up all memory
Message-ID: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>

I have a script that forks off other processes and attempts to manage
them. Here is a stripped down version of the script:

        self.sleepTime = 300
        self.procs = {}
        self.startTimes = {}
        self.cmd = ['python', '/usr/local/motor/motor/app/some_other_script.py']

        while True:
            try:
                self.tools = Tool.objects.filter(ip__isnull=False)
            except Exception, e:
                print 'error from django call: ' + str(e)
                sys.exit(1)

            for tool in self.tools:
                name = tool.name
                if name in self.procs:
                    if self.procs[name].poll() is None:
                        if
(datetime.datetime.now()-self.startTimes[name]) >
datetime.timedelta(hours=12):
                            # it's been running too long - kill it
                            print 'killing script for ' + name + "
it's been running too long"
                            self.procs[name].kill()
                        else:
                            continue

                    if self.procs[name].returncode:
                        print 'scrikpt failed for ' + name + ', error
= ' + str(self.procs[name].returncode)

                    print 'starting script.py for ' + name + ' at ' +
str(datetime.datetime.now())
                    try:
                        self.procs[name] = subprocess.Popen(self.cmd)
                        self.startTimes[name] = datetime.datetime.now()
                    except Exception, e:
                        print 'error from Popen: ' + str(e)
                        sys.exit(1)
                else:
                    print 'starting script.py for ' + name + ' at ' +
str(datetime.datetime.now())
                    try:
                        self.procs[name] = subprocess.Popen(self.cmd)
                        self.startTimes[name] = datetime.datetime.now()
                    except Exception, e:
                        print 'error from Popen: ' + str(e)
                        sys.exit(1)

                time.sleep(self.sleepTime)


The script does what it's intended to do, however after about 2 hours
it has used up all the memory available and the machine hangs. Can
anyone see something that I am doing here that would be using memory
like this? Perhaps some immutable object needs to be repeatedly
recreated?


From rosuav at gmail.com  Wed Mar  5 17:39:47 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 6 Mar 2014 09:39:47 +1100
Subject: script uses up all memory
In-Reply-To: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
Message-ID: <CAPTjJmpzpVC-aDX36mQfnLLOPMrrkkaW7tTo=yYJ0bu1XsrPxA@mail.gmail.com>

On Thu, Mar 6, 2014 at 9:27 AM, Larry Martell <larry.martell at gmail.com> wrote:
> I have a script that forks off other processes and attempts to manage
> them. Here is a stripped down version of the script:
>
>         self.sleepTime = 300

That's not a stand-alone script. What environment is it running in?
Can you reproduce the problem outside of that environment?

Also: Can you simply use multiprocessing rather than going through all
the effort of subprocess.Popen?

ChrisA


From drsalists at gmail.com  Wed Mar  5 17:42:09 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Wed, 5 Mar 2014 14:42:09 -0800
Subject: ANN: Python Job Board - Call for volunteers
In-Reply-To: <530F52DE.9000704@python.org>
References: <530F52DE.9000704@python.org>
Message-ID: <CAGGBd_qPWzPhen2pEPGaEmxM6YvQymyw2t5Ww3aCxBPQpE+_NA@mail.gmail.com>

I hope this means there'll soon be an option to restrict ads seen by
some form of postal code or phone area code (with telecommute
hopefully being an optional wildcard).

On Thu, Feb 27, 2014 at 6:59 AM, M.-A. Lemburg <mal at python.org> wrote:
> [Please help spread the word by forwarding to other relevant mailing lists,
>  user groups, etc. world-wide; thanks :-)]
>
> Dear Python Community,
>
> for many years, the Python Job board (http://legacy.python.org/community/jobs/)
> was run by volunteers - most of the time by just one volunteer at a
> time until they moved on to spend their time on other things.
> We've now reached such a point again.


From tjreedy at udel.edu  Wed Mar  5 18:00:57 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 05 Mar 2014 18:00:57 -0500
Subject: Reference
In-Reply-To: <87iors74re.fsf@elektro.pacujo.net>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <53176aac$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87r46g75t9.fsf@elektro.pacujo.net> <lf81iu$rti$1@reader1.panix.com>
 <87iors74re.fsf@elektro.pacujo.net>
Message-ID: <lf8ab8$8au$1@ger.gmane.org>

On 3/5/2014 3:46 PM, Marko Rauhamaa wrote:
> Grant Edwards <invalid at invalid.invalid>:
>
>> Wrong. If the two objects are not the same, then they will have
>> different ID values. If the ID values are the same, then you've only
>> got one object.
>
> Ok, that circularity again.

Every deductive system starts with some undefined terms. These, along 
with axioms or postulates, are how circularity is avoided. There 
typically is a choice as to which concepts are taken as primitive and 
which are defined in terms of them. In Python, one could take 'object' 
and the notions of same versus different object as primitive.

> Say I implement Python. Say I returned a random number for id(),

In CPython, the int id of an object is arbitrary, somewhat haphazard, 
and effectively random in the colloquial sense of the term.

 > how would that violate the language spec?

It obviously does not as long as the 'random' id obeys the id axioms of 
persistence and uniqueness.

> I think the discussion spawned from the problem of teaching programming
> students the right idea of values and objects. A teacher would like to
> bring in advanced concepts last, but Python seems to force you to get
> them at the very beginning.

Kids learn the notion of object persistence quite early (first year, I 
think). Kids also learn that there are multiple ways of referring to one 
and the same person or object, and that some references ('teacher') can 
be rebound to a different person or object.

-- 
Terry Jan Reedy



From python.list at tim.thechases.com  Wed Mar  5 16:56:51 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Wed, 5 Mar 2014 15:56:51 -0600
Subject: Program Python
In-Reply-To: <DUB406-EAS5040C6D80CD82DA8BF4F2094890@phx.gbl>
References: <DUB406-EAS5040C6D80CD82DA8BF4F2094890@phx.gbl>
Message-ID: <20140305155651.3eb8094d@bigbox.christie.dr>

On 2014-03-05 22:41, Luciano Trespidi wrote:
> I'm very grateful if anyone can helpme to find a good program to
> develop in python lenguage. Thanks

This reminds me of the old joke:

Q: Why are you scratching yourself?

A: Because I'm the only one who knows where I itch!



The best place to find a good program to develop in Python is to look
at what you want to be able to do, but haven't found something that
does what you want.

Perhaps you tire of manually processing files at work and want to
automate it.  Perhaps you want to email your Mum on one random day
each month.  Perhaps you want to calculate lottery numbers according
to your own personal preference. Perhaps you want to make a game.  So
many possibilities.

So look for something that would scratch an itch you have, and go for
it! :-)

-tkc




From larry.martell at gmail.com  Wed Mar  5 19:20:13 2014
From: larry.martell at gmail.com (Larry Martell)
Date: Wed, 5 Mar 2014 19:20:13 -0500
Subject: script uses up all memory
In-Reply-To: <CAPTjJmpzpVC-aDX36mQfnLLOPMrrkkaW7tTo=yYJ0bu1XsrPxA@mail.gmail.com>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CAPTjJmpzpVC-aDX36mQfnLLOPMrrkkaW7tTo=yYJ0bu1XsrPxA@mail.gmail.com>
Message-ID: <CACwCsY4X=yY-xiWgBnaoZ+d0iY=kyZLg_zxuRY=tU-D-McoFZg@mail.gmail.com>

On Wed, Mar 5, 2014 at 5:39 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Thu, Mar 6, 2014 at 9:27 AM, Larry Martell <larry.martell at gmail.com> wrote:
>> I have a script that forks off other processes and attempts to manage
>> them. Here is a stripped down version of the script:
>>
>>         self.sleepTime = 300
>
> That's not a stand-alone script.

No, that is just the part that does the work (inside the 'while
true'). I'll try and post a standalone script tomorrow.

> What environment is it running in?

CentOS 6,4

> Can you reproduce the problem outside of that environment?

I will try that tomorrow.

> Also: Can you simply use multiprocessing rather than going through all
> the effort of subprocess.Popen?

Perhaps. I didn't write this. A client gave it to me and said 'figure
out why it uses up all the memory and hangs.' I've messed around with
for days and cannot see anything that would consume so much memory.


From rosuav at gmail.com  Wed Mar  5 19:33:45 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 6 Mar 2014 11:33:45 +1100
Subject: script uses up all memory
In-Reply-To: <CACwCsY4X=yY-xiWgBnaoZ+d0iY=kyZLg_zxuRY=tU-D-McoFZg@mail.gmail.com>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CAPTjJmpzpVC-aDX36mQfnLLOPMrrkkaW7tTo=yYJ0bu1XsrPxA@mail.gmail.com>
 <CACwCsY4X=yY-xiWgBnaoZ+d0iY=kyZLg_zxuRY=tU-D-McoFZg@mail.gmail.com>
Message-ID: <CAPTjJmqqUDF5KTyegtK8F==voeUjTYV0c=NmX2icwtisVfgrmA@mail.gmail.com>

On Thu, Mar 6, 2014 at 11:20 AM, Larry Martell <larry.martell at gmail.com> wrote:
> On Wed, Mar 5, 2014 at 5:39 PM, Chris Angelico <rosuav at gmail.com> wrote:
>> On Thu, Mar 6, 2014 at 9:27 AM, Larry Martell <larry.martell at gmail.com> wrote:
>>> I have a script that forks off other processes and attempts to manage
>>> them. Here is a stripped down version of the script:
>>>
>>>         self.sleepTime = 300
>>
>> That's not a stand-alone script.
>
> No, that is just the part that does the work (inside the 'while
> true'). I'll try and post a standalone script tomorrow.
>
>> What environment is it running in?
>
> CentOS 6,4

That's not the whole environment, though. There's a mention of Django
- does this run inside some framework?

>> Can you reproduce the problem outside of that environment?
>
> I will try that tomorrow.

Running as a stand-alone script, still under CentOS, would be what I
mean by "outside of that environment". I'm talking about making
something that can be saved to my drive and executed, perhaps with a
stubby subprocess script (eg "import time; time.sleep(86400)").

>> Also: Can you simply use multiprocessing rather than going through all
>> the effort of subprocess.Popen?
>
> Perhaps. I didn't write this. A client gave it to me and said 'figure
> out why it uses up all the memory and hangs.' I've messed around with
> for days and cannot see anything that would consume so much memory.

Ah. Yeah, that would be a fun little job to play with. My random
thought: Do the subprocesses produce spammy log output? If so, the
monitor might be collecting it all and holding it in memory in case
you want it (not knowing that you don't). The default should be to
leave them connected to your process's stdio streams, though, so that
shouldn't be the issue.

ChrisA


From steve+comp.lang.python at pearwood.info  Wed Mar  5 19:35:33 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 06 Mar 2014 00:35:33 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
 <87bnxk73gb.fsf@elektro.pacujo.net>
 <mailman.7837.1394054791.18130.python-list@python.org>
Message-ID: <5317c2d5$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Thu, 06 Mar 2014 08:26:22 +1100, Chris Angelico wrote:

> On Thu, Mar 6, 2014 at 8:14 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> When I talk about an object's memory address, I'm not referring to what
>> might be revealed by gdb, for example. That is, I'm not talking about
>> the process's virtual address space, nor am I talking about the
>> physical address on the address bus. I can simply define that the
>> object's memory address is whatever id() returns.
> 
> Where's the complaints about circularity now? You're saying "But of
> course id() returns the address, as long as we define the address as
> 'whatever id() returns'.". Unimpeachably logical and utterly unhelpful.

That last sentence is wrong. There is nothing logical about just making 
up arbitrary definitions in this way. He could invent *any* definition, 
each more ridiculous than the last:

- it's the object's memory address;

- it's the object's phone number;

- it's the number of baby elephants killed by the object;

- it's the number of intergalactic empires that are, even as we 
  speak, rushing to Earth to invade to gain possession of that
  object;

- it's the weight in metric tonnes of the electrons in the object;

  (Not *actual* electrons of course, just these arbitrary inventions 
  of Marko's definition.)

- it's the length measured in seconds of the bitterness of the 
  object's kidney;


and of course:

- the number of angels that can dance on the object.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From larry.martell at gmail.com  Wed Mar  5 19:43:23 2014
From: larry.martell at gmail.com (Larry Martell)
Date: Wed, 5 Mar 2014 19:43:23 -0500
Subject: script uses up all memory
In-Reply-To: <CAPTjJmqqUDF5KTyegtK8F==voeUjTYV0c=NmX2icwtisVfgrmA@mail.gmail.com>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CAPTjJmpzpVC-aDX36mQfnLLOPMrrkkaW7tTo=yYJ0bu1XsrPxA@mail.gmail.com>
 <CACwCsY4X=yY-xiWgBnaoZ+d0iY=kyZLg_zxuRY=tU-D-McoFZg@mail.gmail.com>
 <CAPTjJmqqUDF5KTyegtK8F==voeUjTYV0c=NmX2icwtisVfgrmA@mail.gmail.com>
Message-ID: <CACwCsY5jmsNxU1-JMiK2_S7PsEy+2LV-kEo1gXktv7sd_q9GKg@mail.gmail.com>

On Wed, Mar 5, 2014 at 7:33 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Thu, Mar 6, 2014 at 11:20 AM, Larry Martell <larry.martell at gmail.com> wrote:
>> On Wed, Mar 5, 2014 at 5:39 PM, Chris Angelico <rosuav at gmail.com> wrote:
>>> On Thu, Mar 6, 2014 at 9:27 AM, Larry Martell <larry.martell at gmail.com> wrote:
>>>> I have a script that forks off other processes and attempts to manage
>>>> them. Here is a stripped down version of the script:
>>>>
>>>>         self.sleepTime = 300
>>>
>>> That's not a stand-alone script.
>>
>> No, that is just the part that does the work (inside the 'while
>> true'). I'll try and post a standalone script tomorrow.
>>
>>> What environment is it running in?
>>
>> CentOS 6.4
>
> That's not the whole environment, though. There's a mention of Django
> - does this run inside some framework?

The system this is part of uses Django, and this script makes use of
the django ORM, but it doesn't do any web stuff itself. It just kicks
off another script once for each tool found in the database, and
ensure that there's just one script pre tool running at a time, and
that no single script runs too long. The django part can easily be
removed.

>>> Can you reproduce the problem outside of that environment?
>>
>> I will try that tomorrow.
>
> Running as a stand-alone script, still under CentOS, would be what I
> mean by "outside of that environment". I'm talking about making
> something that can be saved to my drive and executed, perhaps with a
> stubby subprocess script (eg "import time; time.sleep(86400)").

Yes, I understand what you mean.

>
>>> Also: Can you simply use multiprocessing rather than going through all
>>> the effort of subprocess.Popen?
>>
>> Perhaps. I didn't write this. A client gave it to me and said 'figure
>> out why it uses up all the memory and hangs.' I've messed around with
>> for days and cannot see anything that would consume so much memory.
>
> Ah. Yeah, that would be a fun little job to play with. My random
> thought: Do the subprocesses produce spammy log output? If so, the
> monitor might be collecting it all and holding it in memory in case
> you want it (not knowing that you don't). The default should be to
> leave them connected to your process's stdio streams, though, so that
> shouldn't be the issue.

Ohh, that's a good random thought. I'll try that tomorrow and see if
that's the issue.


From rosuav at gmail.com  Wed Mar  5 19:50:10 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 6 Mar 2014 11:50:10 +1100
Subject: Reference
In-Reply-To: <5317c2d5$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
 <87bnxk73gb.fsf@elektro.pacujo.net>
 <mailman.7837.1394054791.18130.python-list@python.org>
 <5317c2d5$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmrroQkocnwWw0-S75bKObxqTSpiixxPn=bzu=W5VnEe8g@mail.gmail.com>

On Thu, Mar 6, 2014 at 11:35 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Thu, 06 Mar 2014 08:26:22 +1100, Chris Angelico wrote:
>
>> Where's the complaints about circularity now? You're saying "But of
>> course id() returns the address, as long as we define the address as
>> 'whatever id() returns'.". Unimpeachably logical and utterly unhelpful.
>
> That last sentence is wrong. There is nothing logical about just making
> up arbitrary definitions in this way. He could invent *any* definition,
> each more ridiculous than the last:

I mean logical in the sense of pure logic.

If all spam is edible-food
And if this-can is spam
Then this-can is edible-food

The opening premise is false (I wouldn't want to eat a punctured can
that's been sitting around for a few months), but it's still perfectly
logical. The conclusion is guaranteed to be true as long as the
premises are.

In that sense of the word, the statement is indeed logical. That
doesn't stop it from being wrong, but it is logical.

If the 'is' comparison is reflexive,
And if three is four,
Then four is three.

Perfectly logical.

He's saying that the address of an object is simply "whatever id()
returns for that object". Since Python doesn't currently have any
other concept of object addresses, that definition isn't in conflict
with anything. Then he says, look! the id() function returns the
object's address. Well, duh, that's how you defined the address. It's
logical. Of course it returns "the address", since "the address" has
been defined as what it returns. But it doesn't achieve anything to
prove that.

ChrisA


From marko at pacujo.net  Wed Mar  5 19:52:38 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 06 Mar 2014 02:52:38 +0200
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
 <87bnxk73gb.fsf@elektro.pacujo.net>
 <mailman.7840.1394055453.18130.python-list@python.org>
Message-ID: <87mwh45esp.fsf@elektro.pacujo.net>

Ben Finney <ben+python at benfinney.id.au>:

> Marko Rauhamaa <marko at pacujo.net> writes:
>> When I talk about an object's memory address, I'm not referring to
>> what might be revealed by gdb, for example. That is, I'm not talking
>> about the process's virtual address space, nor am I talking about the
>> physical address on the address bus. I can simply define that the
>> object's memory address is whatever id() returns.
>
> Then this does not count as a leaky abstraction. All you're saying is
> that the ?id(foo)? result is a representation of the object identity,
> which is entirely at the level of the abstraction. Nothing is leaked.

I wasn't making a point about a leaky abstraction.

I was just saying talking about id() as a memory address isn't all that
bad. It's a bit like rolling down your power windows or turning up the
volume, when there's nothing to roll or turn. There's no risk of getting
your program wrong.


Marko


From ben+python at benfinney.id.au  Wed Mar  5 20:05:18 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 06 Mar 2014 12:05:18 +1100
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest>
 <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
 <87bnxk73gb.fsf@elektro.pacujo.net>
 <mailman.7840.1394055453.18130.python-list@python.org>
 <87mwh45esp.fsf@elektro.pacujo.net>
Message-ID: <85eh2gcf1t.fsf@benfinney.id.au>

Marko Rauhamaa <marko at pacujo.net> writes:

> Ben Finney <ben+python at benfinney.id.au>:
>
> > Then this does not count as a leaky abstraction. All you're saying is
> > that the ?id(foo)? result is a representation of the object identity,
> > which is entirely at the level of the abstraction. Nothing is leaked.
>
> I wasn't making a point about a leaky abstraction.

Can we conclude that you've changed your position on this, then? You now
accept that Python's object identity abstraction is not leaky?

In the absence of you demonstrating a leak in that abstraction, we can
ignore the assertion.

-- 
 \     ?For myself, I am an optimist ? it does not seem to be much use |
  `\              being anything else.? ?Winston Churchill, 1954-11-09 |
_o__)                                                                  |
Ben Finney



From harrismh777 at gmail.com  Wed Mar  5 20:24:44 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Wed, 5 Mar 2014 17:24:44 -0800 (PST)
Subject: How security holes happen
In-Reply-To: <mailman.7850.1394065503.18130.python-list@python.org>
References: <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
 <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
 <d83922b0-2969-4fa1-aa3a-075f7ad4c44a@googlegroups.com>
 <CAPTjJmpCiNC7HHSQwmD4piTQt2VJY4mjQVSMvH=uCVqywm8ifQ@mail.gmail.com>
 <mailman.7850.1394065503.18130.python-list@python.org>
Message-ID: <5adebc12-aa37-4139-82d8-563f46a27dc0@googlegroups.com>

On Wednesday, March 5, 2014 6:24:52 PM UTC-6, Dennis Lee Bieber wrote:
> 	I must have had a deprived life...
> 
> 	The only "debug" on a home system I ever used was the one in LS-DOS.
> And even then, it was only because an OS update disk arrived with a bad
> sector and could not be copied.

   Not many people realized what they had in front of them. The only reason you
might is if you 'grew up' on a system that required machine coding;  like the
Wang 700 series, or the MITS Altair 8800, or the VIC 20 with VicMon.

   I grew up with all three. So, before I ever learned a line of BASIC I was coding 
machine language (not assembler) on the three platforms above... the wang 
used integrated circuits, but had to processor chip;  the MITS used the very first
8080 chip from Intel, and the VIC 20 used the 6502 from Motorola. My first 
personal computer (I did not own it, it was temporarily loaned to me) was the 
VIC 20.  It only had 5k of memory, so anyone who did any real programming 
on it purchased the VicMon cartridge which was a 'machine language monitor'.
It was "DEBUG.COM" for the VIC 20. 

   When I got the first copy of DOS on floppy and saw DEBUG.COM I knew 
instantly what it was... a machine language monitor system for reading and 
writing machine code (8086 / 8088) in memory, or to disk sectors, or to disk
as a file-name.  It wasn't just a debugger---hardly! It was (and still is, yes, I 
still use it) a simple clean full-blown machine language monitor capable today
just as then, to build sophisticated applications with 1's and 0's/

   It was also my cup of tea, as it were.  The folks who used the MITS Altair 8800
hated punching code in by hand; gets old fast.  But not for me. I loved it, because
I was as interested in the 8080 processor as I was in writing programs for it; it was
great fun experimenting with memory and the processor.

   marcus


From harrismh777 at gmail.com  Wed Mar  5 20:36:55 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Wed, 5 Mar 2014 17:36:55 -0800 (PST)
Subject: test
Message-ID: <bd339837-a628-4541-9813-6fea8745a498@googlegroups.com>

test please disregard


From python at mrabarnett.plus.com  Wed Mar  5 20:40:05 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Thu, 06 Mar 2014 01:40:05 +0000
Subject: How security holes happen
In-Reply-To: <5adebc12-aa37-4139-82d8-563f46a27dc0@googlegroups.com>
References: <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
 <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
 <d83922b0-2969-4fa1-aa3a-075f7ad4c44a@googlegroups.com>
 <CAPTjJmpCiNC7HHSQwmD4piTQt2VJY4mjQVSMvH=uCVqywm8ifQ@mail.gmail.com>
 <mailman.7850.1394065503.18130.python-list@python.org>
 <5adebc12-aa37-4139-82d8-563f46a27dc0@googlegroups.com>
Message-ID: <5317D1F5.5080907@mrabarnett.plus.com>

On 2014-03-06 01:24, Mark H. Harris wrote:
> On Wednesday, March 5, 2014 6:24:52 PM UTC-6, Dennis Lee Bieber
> wrote:
>> I must have had a deprived life...
>>
>> The only "debug" on a home system I ever used was the one in
>> LS-DOS. And even then, it was only because an OS update disk
>> arrived with a bad sector and could not be copied.
>
> Not many people realized what they had in front of them. The only
> reason you might is if you 'grew up' on a system that required
> machine coding;  like the Wang 700 series, or the MITS Altair 8800,
> or the VIC 20 with VicMon.
>
> I grew up with all three. So, before I ever learned a line of BASIC I
> was coding machine language (not assembler) on the three platforms
> above... the wang used integrated circuits, but had to processor
> chip;  the MITS used the very first 8080 chip from Intel, and the VIC
> 20 used the 6502 from Motorola.
>
The 6502 came from MOS Technology. Motorola made the 6800.

> My first personal computer (I did not own it, it was temporarily
> loaned to me) was the VIC 20.  It only had 5k of memory, so anyone
> who did any real programming on it purchased the VicMon cartridge
> which was a 'machine language monitor'. It was "DEBUG.COM" for the
> VIC 20.
>
5K? Luxury! I started with the Science of Cambridge Mk14. Including the
RAM on the I/O chip, it had 640 bytes.

> When I got the first copy of DOS on floppy and saw DEBUG.COM I knew
> instantly what it was... a machine language monitor system for
> reading and writing machine code (8086 / 8088) in memory, or to disk
>  sectors, or to disk as a file-name.  It wasn't just a
> debugger---hardly! It was (and still is, yes, I still use it) a
> simple clean full-blown machine language monitor capable today just
> as then, to build sophisticated applications with 1's and 0's/
>
> It was also my cup of tea, as it were.  The folks who used the MITS
> Altair 8800 hated punching code in by hand; gets old fast.  But not
> for me. I loved it, because I was as interested in the 8080 processor
> as I was in writing programs for it; it was great fun experimenting
> with memory and the processor.
>


From anikom15 at gmail.com  Wed Mar  5 20:56:14 2014
From: anikom15 at gmail.com (=?ISO-8859-1?Q?Westley_Mart=EDnez?=)
Date: Wed, 5 Mar 2014 17:56:14 -0800 (PST)
Subject: Origin of 'self'
In-Reply-To: <531426b8$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
 <531426b8$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <1634feec-9f23-4f46-bd38-f5f6ef3b0113@googlegroups.com>

Why did C++ use this? I don't really like this. It doesn't sound right. I think it's because I have trouble saying the th sound without getting my mouth full of spit.

Thankfully you don't often need to use this in C++ like you do with self in Python.


From harrismh777 at gmail.com  Wed Mar  5 21:07:10 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Wed, 5 Mar 2014 18:07:10 -0800 (PST)
Subject: How security holes happen
In-Reply-To: <mailman.7856.1394070008.18130.python-list@python.org>
References: <mailman.7759.1393972610.18130.python-list@python.org>
 <87d2i1mvg7.fsf@elektro.pacujo.net>
 <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
 <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
 <d83922b0-2969-4fa1-aa3a-075f7ad4c44a@googlegroups.com>
 <CAPTjJmpCiNC7HHSQwmD4piTQt2VJY4mjQVSMvH=uCVqywm8ifQ@mail.gmail.com>
 <mailman.7850.1394065503.18130.python-list@python.org>
 <5adebc12-aa37-4139-82d8-563f46a27dc0@googlegroups.com>
 <mailman.7856.1394070008.18130.python-list@python.org>
Message-ID: <76ee4081-4494-4a53-a05e-3da8fdcb90d1@googlegroups.com>

On Wednesday, March 5, 2014 7:40:05 PM UTC-6, MRAB wrote:
> 
> The 6502 came from MOS Technology. Motorola made the 6800.

    Well, not exactly. The MOS 6502 is to the Motorola 6800 what the Zilog
Z80 was to the Intel 8080.  
    The same engineers who designed the 6800 moved out and then designed
the 6502; actually ended up in a law suit of sorts--- but I don't remember the
details. Anyway, the 6502 was bought outright by Commodore, and the rest
is history with the VIC20.
    The engineers at Intel did the same thing... moved out and started Zilog
(which still exists today) and began their work on the Z80.  By the by, the Z80
is still embedded in many applications today. Although, its not on a 40 pin dip
any longer; its a small square about the size of a postage stamp. That is what 
powers the TI 84+ and the TI 83+ graphing programable calculators. I do some
machine coding on the TI 84+ because it can be done on-the-device!
    The 68000 is the motorola chip that powers the TI89 graphing programable
calculator ( my favorite ).  Its not so easy to program it with machine code, because
the kernel binaries are not well documented (TI hides them) and the user community
hasn't probed it enough to know how does it really work.

> 5K? Luxury! I started with the Science of Cambridge Mk14. Including the
> RAM on the I/O chip, it had 640 bytes.

    Oh, I know. I thought 5k was a tremendous about of memory at the time, but we
soon built and expanded for the slot, added 16k of memory (hand wire-wrapped thank
you) and then plugged the VicMon (actually HES MON) into that.
    Do you remember the IAS (Maniac) at the Institute for Advanced Study (Johnny von Neumann's
baby) ?   It only had 5k of memory too!  They had to use punched cards or punched tape 
for intermediate results when they were doing their runs calculating the wave function for
the hydrogen bomb.   At the time, Johnny said, " there will never be a need for for than
five machines like this in the whole world!"

     marcus


From wuwei23 at gmail.com  Wed Mar  5 21:12:15 2014
From: wuwei23 at gmail.com (alex23)
Date: Thu, 06 Mar 2014 12:12:15 +1000
Subject: Reference
In-Reply-To: <87mwh45esp.fsf@elektro.pacujo.net>
References: <53144e8d$0$2149$426a74cc@news.free.fr>	<1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>	<85ppm3httu.fsf@benfinney.id.au>
 <lf2sjk$7d4$1@ger.gmane.org>	<20140303155112.46e34ff8@bigbox.christie.dr>	<mailman.7666.1393884138.18130.python-list@python.org>	<87siqy7whs.fsf@elektro.pacujo.net>	<53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>	<mailman.7693.1393910647.18130.python-list@python.org>	<op.xb75g7ap5079vu@gnudebeest>	<roy-A9E76C.21091704032014@news.panix.com>	<164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>	<5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>	<e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>	<53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>	<87mwh475bc.fsf@elektro.pacujo.net>	<mailman.7833.1394053296.18130.python-list@python.org>	<87bnxk73gb.fsf@elektro.pacujo.net>	<mailman.7840.1394055453.18130.python-list@python.org>
 <87mwh45esp.fsf@elektro.pacujo.net>
Message-ID: <lf8lhv$t6c$1@dont-email.me>

On 6/03/2014 10:52 AM, Marko Rauhamaa wrote:
> I was just saying talking about id() as a memory address isn't all that
> bad. It's a bit like rolling down your power windows or turning up the
> volume, when there's nothing to roll or turn. There's no risk of getting
> your program wrong.

Unless you're talking about, say, the PyPy implementation, for which id 
is _not_ a memory address at all.

Why insist on using "memory address" rather than "unique identifier", 
when the latter is fundamentally more correct?



From roy at panix.com  Wed Mar  5 21:31:51 2014
From: roy at panix.com (Roy Smith)
Date: Wed, 05 Mar 2014 21:31:51 -0500
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7815.1394022463.18130.python-list@python.org>
 <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-3C3E69.21315105032014@news.panix.com>

In article <53176225$0$29987$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> Physics is the fundamental science, at least according to the physicists, 
> and Real Soon Now they'll have a Theory Of Everything, something small 
> enough to print on a tee-shirt, which will explain everything. At least 
> in principle.

A mathematician, a chemist, and a physicist are arguing the nature of 
prime numbers.  The chemist says, "All odd numbers are prime.  Look, I 
can prove it.  Three is prime.  Five is prime.  Seven is prime".  The 
mathematician says, "That's nonsense.  Nine is not prime".  The 
physicist looks at him and says, "Hmmmm, you may be right, but eleven 
is prime, and thirteen is prime.  It appears that within the limits of 
experimental error, all odd number are indeed prime!"


From dihedral88888 at gmail.com  Wed Mar  5 21:39:49 2014
From: dihedral88888 at gmail.com (88888 Dihedral)
Date: Wed, 5 Mar 2014 18:39:49 -0800 (PST)
Subject: How security holes happen
In-Reply-To: <izuRu.12475$wf3.1354@fx10.am4>
References: <lf22t1$sgh$1@ger.gmane.org>
 <mailman.7670.1393885170.18130.python-list@python.org>
 <izuRu.12475$wf3.1354@fx10.am4>
Message-ID: <a52ca76f-0c69-41f7-9dcd-47b0d6a620f3@googlegroups.com>

On Wednesday, March 5, 2014 8:52:31 AM UTC+8, Andrew Cooper wrote:
> On 03/03/2014 22:19, Cameron Simpson wrote:
> 
> > On 03Mar2014 09:17, Neal Becker <ndbecker2 at gmail.com> wrote:
> 
> >>  Charles R Harris <charlesr.harris at gmail.com> Wrote in message:
> 
> >>>
> 
> >>
> 
> >> Imo the lesson here is never write in low level c. Use modern
> 
> >>  languages with well designed exception handling.
> 
> > 
> 
> > What, and rely on someone else's low level C?
> 
> > 
> 
> 
> 
> Why is C the lowest denominator?
> 
> 
> 
> Even with correctly written C and assembly, how can you be sure that
> 
> your processor is executing the SYSRET instruction safely?
> 
> (CVE-2012-0217 for anyone interested)
> 
> 
> 
> ~Andrew

It is not  difficult to write C with
mixed assembly codes for different
CPUs. 

#ifdef ASM  
/* asm follows */
....

#ifdef CPUTYPES 
/* insert CPU ASMS for different 
CPUs carefully here */



From albert at spenarnc.xs4all.nl  Wed Mar  5 21:51:54 2014
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 06 Mar 2014 02:51:54 GMT
Subject: Python programming
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <mailman.6815.1392256827.18130.python-list@python.org>
 <ldhcau$d9v$1@reader1.panix.com> <roy-A94C1B.22041912022014@news.panix.com>
Message-ID: <5317e2ca$0$9232$e4fe514c@dreader35.news.xs4all.nl>

In article <roy-A94C1B.22041912022014 at news.panix.com>,
Roy Smith  <roy at panix.com> wrote:
>In article <ldhcau$d9v$1 at reader1.panix.com>,
> Grant Edwards <invalid at invalid.invalid> wrote:
>
>> On 2014-02-13, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>>
>> >    An S-100 wire-wrap board.
>>
>> Yup, been there done that!
>
>Never did S-100, but I did do a custom Unibus card (wirewrap).
>
>You know you're working with a Real Computer (tm) when the +5V power
>supply can deliver as much current as an arc welder.

I've a 64 node Parsytec transputer system in the hall way with
dual 5V 100A power supplies. Does that count?

Groetjes Albert
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From steve+comp.lang.python at pearwood.info  Wed Mar  5 22:01:15 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 06 Mar 2014 03:01:15 GMT
Subject: Reference
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <55d6a455-1856-4fd6-ac4b-c277ff7e2bd1@googlegroups.com>
 <53176aac$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87r46g75t9.fsf@elektro.pacujo.net>
Message-ID: <5317e4fb$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Wed, 05 Mar 2014 22:23:46 +0200, Marko Rauhamaa wrote:

> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
> 
>> There is no metaphysical implication from Python's "is" operator. If
>> the operator had precisely the same behaviour, but was called "same",
>> as in:
>>
>> a same b
>> => returns True if a and b are the same object => returns False if a
>> and b are not the same object
>>
>> would you claim there was a metaphysical implication?
> 
> I would. You are not defining anything because you are not explaining
> what "same object" means.

I mean exactly the same thing by "same object" as you do when you use it:

> Set theory obeys the so-called extensionality principle: if two objects
> are indistinguishable in every way, they are one and the same object.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From felixonmars at gmail.com  Wed Mar  5 22:09:06 2014
From: felixonmars at gmail.com (Felix Yan)
Date: Thu, 06 Mar 2014 11:09:06 +0800
Subject: Diagnose a segfault in ipython/readline
Message-ID: <2114014.zHAFJyoHbS@felix-arch>

Hi,

I'm getting a reproducible crash in ipython, but not sure what upstream it 
should belong to.

The crash happens with python 2.7.6/3.3.4, with readline 6.3.

Steps to reproduce:

- run ipython
- input some random char sequence that you never inputed (like 
"ae3r0gka03k0k23"), don't press Enter
- press "Up", followed by any key

Backtrace pasted here: https://paste.xinu.at/cg7/
Downstream bug report on Arch Linux: https://bugs.archlinux.org/task/39144

Any help would be really appreciated!

Regards,
Felix Yan
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From steve+comp.lang.python at pearwood.info  Wed Mar  5 22:06:40 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 06 Mar 2014 03:06:40 GMT
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7815.1394022463.18130.python-list@python.org>
 <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
 <roy-3C3E69.21315105032014@news.panix.com>
Message-ID: <5317e640$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Wed, 05 Mar 2014 21:31:51 -0500, Roy Smith wrote:

> In article <53176225$0$29987$c3e8da3$5496439d at news.astraweb.com>,
>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
> 
>> Physics is the fundamental science, at least according to the
>> physicists, and Real Soon Now they'll have a Theory Of Everything,
>> something small enough to print on a tee-shirt, which will explain
>> everything. At least in principle.
> 
> A mathematician, a chemist, and a physicist are arguing the nature of
> prime numbers.  The chemist says, "All odd numbers are prime.  Look, I
> can prove it.  Three is prime.  Five is prime.  Seven is prime".  The
> mathematician says, "That's nonsense.  Nine is not prime".  The
> physicist looks at him and says, "Hmmmm, you may be right, but eleven is
> prime, and thirteen is prime.  It appears that within the limits of
> experimental error, all odd number are indeed prime!"

They ask a computer programmer to adjudicate who is right, so he writes a 
program to print out all the primes:

1 is prime
1 is prime
1 is prime
1 is prime
1 is prime
...



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Wed Mar  5 22:14:49 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 6 Mar 2014 14:14:49 +1100
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
In-Reply-To: <5317e640$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7815.1394022463.18130.python-list@python.org>
 <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
 <roy-3C3E69.21315105032014@news.panix.com>
 <5317e640$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmpUjy6cqP43U9QCFELdGEdEqv8YWftEPY1O37ZcAnttTg@mail.gmail.com>

On Thu, Mar 6, 2014 at 2:06 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> They ask a computer programmer to adjudicate who is right, so he writes a
> program to print out all the primes:
>
> 1 is prime
> 1 is prime
> 1 is prime
> 1 is prime
> 1 is prime

And he claimed that he was correct, because he had - as is known to be
true in reality - a countably infinite number of primes.

ChrisA


From invalid at invalid.invalid  Wed Mar  5 22:34:10 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Thu, 6 Mar 2014 03:34:10 +0000 (UTC)
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7815.1394022463.18130.python-list@python.org>
 <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
 <roy-3C3E69.21315105032014@news.panix.com>
Message-ID: <lf8qbi$5v$1@reader1.panix.com>

On 2014-03-06, Roy Smith <roy at panix.com> wrote:
> In article <53176225$0$29987$c3e8da3$5496439d at news.astraweb.com>,
>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>
>> Physics is the fundamental science, at least according to the
>> physicists, and Real Soon Now they'll have a Theory Of Everything,
>> something small enough to print on a tee-shirt, which will explain
>> everything. At least in principle.
>
> A mathematician, a chemist, and a physicist are arguing the nature of 
> prime numbers.  The chemist says, "All odd numbers are prime.  Look, I 
> can prove it.  Three is prime.  Five is prime.  Seven is prime".  The 
> mathematician says, "That's nonsense.  Nine is not prime".  The 
> physicist looks at him and says, "Hmmmm, you may be right, but eleven 
> is prime, and thirteen is prime.  It appears that within the limits of 
> experimental error, all odd number are indeed prime!"

Assuming spherical odd numbers in a vacuum on a frictionless surface,
of course.

-- 
Grant




From roy at panix.com  Wed Mar  5 23:05:02 2014
From: roy at panix.com (Roy Smith)
Date: Wed, 05 Mar 2014 23:05:02 -0500
Subject: Working with the set of real numbers (was: Finding size of
 Variable)
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <531688b1$0$25064$e4fe514c@dreader37.news.xs4all.nl>
 <53169cd9$0$2923$c3e8da3$76491128@news.astraweb.com>
 <c39d5b44-6c7b-40d1-bbb5-791a36af6857@googlegroups.com>
 <roy-38F1BC.23253704032014@news.panix.com>
 <5316d7a0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7815.1394022463.18130.python-list@python.org>
 <53176225$0$29987$c3e8da3$5496439d@news.astraweb.com>
 <roy-3C3E69.21315105032014@news.panix.com>
 <5317e640$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-80F6FB.23050205032014@news.panix.com>

In article <5317e640$0$29985$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> On Wed, 05 Mar 2014 21:31:51 -0500, Roy Smith wrote:
> 
> > In article <53176225$0$29987$c3e8da3$5496439d at news.astraweb.com>,
> >  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
> > 
> >> Physics is the fundamental science, at least according to the
> >> physicists, and Real Soon Now they'll have a Theory Of Everything,
> >> something small enough to print on a tee-shirt, which will explain
> >> everything. At least in principle.
> > 
> > A mathematician, a chemist, and a physicist are arguing the nature of
> > prime numbers.  The chemist says, "All odd numbers are prime.  Look, I
> > can prove it.  Three is prime.  Five is prime.  Seven is prime".  The
> > mathematician says, "That's nonsense.  Nine is not prime".  The
> > physicist looks at him and says, "Hmmmm, you may be right, but eleven is
> > prime, and thirteen is prime.  It appears that within the limits of
> > experimental error, all odd number are indeed prime!"
> 
> They ask a computer programmer to adjudicate who is right, so he writes a 
> program to print out all the primes:
> 
> 1 is prime
> 1 is prime
> 1 is prime
> 1 is prime
> 1 is prime
> ...

So, a mathematician, a biologist, and a physicist are watching a house.  
The physicist says, "It appears to be empty".  Sometime later, a man and 
a woman go into the house.  Shortly after that, the man and the woman 
come back out, with a child.  The biologist says, "They must have 
reproduced".  The mathematician says, "If one more person goes into the 
house, it'll be empty again".


From dihedral88888 at gmail.com  Wed Mar  5 23:05:28 2014
From: dihedral88888 at gmail.com (88888 Dihedral)
Date: Wed, 5 Mar 2014 20:05:28 -0800 (PST)
Subject: Python programming
In-Reply-To: <mailman.6844.1392305455.18130.python-list@python.org>
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <CACwCsY5jdmbp-atiL7jjHLUkUmtG6uOrJ1Bj2mWRG+7s-KdN-w@mail.gmail.com>
 <CAN8CLgkF9wy41Q9YckU2_+_xMZYgshkuUWT2rLeqAuTAeeBfbA@mail.gmail.com>
 <mailman.6844.1392305455.18130.python-list@python.org>
Message-ID: <bcf71212-77b9-403b-b3de-ba2172c621be@googlegroups.com>

On Thursday, February 13, 2014 11:30:27 PM UTC+8, Neil Cerutti wrote:
> On 2014-02-12, Tim Delaney <timothy.c.delaney at gmail.com> wrote:
> 
> > OK - it's degenerated into one of these threads - I'm going to
> 
> > participate.
> 
> 
> 
> Me, too!
> 
> 
> 
> I wrote lots of programs, strictly for fun, on every personal
> 
> computer I got my hands on. Toward the end of the 80's personal
> 
> computer's stopped coming equipped with programming environments,
> 
> and I stopped programming.
> 
> 
> 
> I eventually learned  some computing theory in college where they
> 
> taught C and the rudiments of C++.
> 
> 
> 
> Thanks to the open-source movement we've returned to the days
> 
> when anybody can program for zero cash. You can program well
> 
> enough to amuse yourself with very little effort indeed.
> 
> 
> 
> To get from there to being able to write programs to do useful
> 
> things for yourself is a lot harder, but this is the niche that
> 
> Python fills excellent well. If this is what you want to do,
> 
> Python is a good way to go.
> 
> 
> 
> That's still just the beginning, but it's a pretty good place.
> 
> 
> 
> -- 
> 
> Neil Cerutti

I wrote programs for viewing gif, pcx,
bmp, and jpg images in 1991 to 1992.

Also I was planning to write an 
Lotus123 clone at the time, but 
I was too lazy to chunk out that
project in 1993.

 


From nad at acm.org  Wed Mar  5 23:15:31 2014
From: nad at acm.org (Ned Deily)
Date: Wed, 05 Mar 2014 20:15:31 -0800
Subject: Diagnose a segfault in ipython/readline
References: <2114014.zHAFJyoHbS@felix-arch>
Message-ID: <nad-F1D106.20153105032014@news.gmane.org>

In article <2114014.zHAFJyoHbS at felix-arch>,
 Felix Yan <felixonmars at gmail.com> wrote:
> I'm getting a reproducible crash in ipython, but not sure what upstream it 
> should belong to.
> 
> The crash happens with python 2.7.6/3.3.4, with readline 6.3.
> 
> Steps to reproduce:
> 
> - run ipython
> - input some random char sequence that you never inputed (like 
> "ae3r0gka03k0k23"), don't press Enter
> - press "Up", followed by any key
> 
> Backtrace pasted here: https://paste.xinu.at/cg7/
> Downstream bug report on Arch Linux: https://bugs.archlinux.org/task/39144
> 
> Any help would be really appreciated!

AFAIK, the only recent Python issue related to GNU readline was 
Issue20374 but it seems you've already eliminated that.  The current 
assumption is that Python 2.7.6+, 3.3.5, and 3.4.0 have no problems with 
readline 6.3.  If you end up believing that there is a Python problem 
with it, please open an issue on the Python bug tracker.  Thanks!

http://bugs.python.org

-- 
 Ned Deily,
 nad at acm.org



From offroad.adventures.engr at gmail.com  Wed Mar  5 23:19:56 2014
From: offroad.adventures.engr at gmail.com (Beowulf)
Date: Wed, 5 Mar 2014 20:19:56 -0800 (PST)
Subject: Python programming
In-Reply-To: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
Message-ID: <98df529b-afe3-4f96-92ff-ff6e936d3dda@googlegroups.com>

Once you master one language it is easy to understand other.  I mastered C in my younger years, writing signal handlers and thread on Solaris and AIX.

It it not the syntax, that comes easy, it is building the correct algorithm that matters.

The best way to learn is make some thing useful that you need.  I would suggest project with Raspberry Pi to learn python.

On Tuesday, February 11, 2014 4:21:29 PM UTC-8, ngangsia akumbo wrote:
> Please i have a silly question to ask.
> 
> 
> 
> How long did it take you to learn how to write programs?
> 
> 
> 
> What is the best way i can master thinker?
> 
> I know the syntax but using it to write a program is a problem


From dan at tombstonezero.net  Wed Mar  5 23:43:35 2014
From: dan at tombstonezero.net (Dan Sommers)
Date: Thu, 6 Mar 2014 04:43:35 +0000 (UTC)
Subject: Python programming
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <98df529b-afe3-4f96-92ff-ff6e936d3dda@googlegroups.com>
Message-ID: <lf8udn$eag$1@dont-email.me>

On Wed, 05 Mar 2014 20:19:56 -0800, Beowulf wrote:

> Once you master one language it is easy to understand other ...

Once you master one language, the next one is hard.  After that, they
get easier.


From roy at panix.com  Wed Mar  5 23:51:28 2014
From: roy at panix.com (Roy Smith)
Date: Wed, 05 Mar 2014 23:51:28 -0500
Subject: Python programming
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <98df529b-afe3-4f96-92ff-ff6e936d3dda@googlegroups.com>
 <lf8udn$eag$1@dont-email.me>
Message-ID: <roy-9164B8.23512805032014@news.panix.com>

In article <lf8udn$eag$1 at dont-email.me>,
 Dan Sommers <dan at tombstonezero.net> wrote:

> On Wed, 05 Mar 2014 20:19:56 -0800, Beowulf wrote:
> 
> > Once you master one language it is easy to understand other ...
> 
> Once you master one language, the next one is hard.  After that, they
> get easier.

And then you get to PHP.


From felixonmars at gmail.com  Thu Mar  6 01:11:10 2014
From: felixonmars at gmail.com (Felix Yan)
Date: Thu, 06 Mar 2014 14:11:10 +0800
Subject: Diagnose a segfault in ipython/readline
In-Reply-To: <nad-F1D106.20153105032014@news.gmane.org>
References: <2114014.zHAFJyoHbS@felix-arch>
 <nad-F1D106.20153105032014@news.gmane.org>
Message-ID: <1779169.vC7H4N7YzS@felix-arch>

On Wednesday, March 05, 2014 20:15:31 Ned Deily wrote:
> The current
> assumption is that Python 2.7.6+, 3.3.5, and 3.4.0 have no problems with
> readline 6.3.

Thank you.

I just gave a try to 3.4.0b2 with readline 6.3, and still get the same 
segfault. Not sure the version is new enough though.

Also we reported the problem on readline mailing list first, so if they end up 
thinking there's something that python need to fix, I'll open a bug on the 
Python bug tracker.

Thanks again!

Regards,
Felix Yan
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From steve at pearwood.info  Thu Mar  6 01:17:05 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 06 Mar 2014 06:17:05 GMT
Subject: Python programming
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <98df529b-afe3-4f96-92ff-ff6e936d3dda@googlegroups.com>
Message-ID: <531812e0$0$2923$c3e8da3$76491128@news.astraweb.com>

On Wed, 05 Mar 2014 20:19:56 -0800, Beowulf wrote:

> Once you master one language it is easy to understand other.  

Depends on the languages. Learning Forth doesn't make it easier to learn 
Perl. Learning Pascal doesn't make Smalltalk easier.


-- 
Steven


From shulamitmi3 at gmail.com  Thu Mar  6 01:53:46 2014
From: shulamitmi3 at gmail.com (=?UTF-8?B?16nXldec157XmdeqINee15nXqNec?=)
Date: Wed, 5 Mar 2014 22:53:46 -0800 (PST)
Subject: NameError: name 'pyver' is not defined
Message-ID: <be63ef8b-c37b-4cbb-93ac-edb72f64aa41@googlegroups.com>

Hello,

We have python 2.6 & 3.2 installed on Sun solaris.
When running py utility, we get the below error:

"NameError: global name 'execfile' is not defined"


> p4convert-cvs.py
EXCEPTION: [Errno 17] File exists: './LOGS'
Traceback (most recent call last):
  File "p4convert-cvs.py", line 134, in <module>
    cvstop4lib.readconfig(configfile=args.config)
  File "/bzqchome/bzq/ccbzq/mb_ccbzq/Perforce/p4convert/cvstop4lib.py", line 61, in readconfig
    execfile(configfile,globals()) # read in the config file - must be valid Python, evaluated in the context of this file
NameError: global name 'execfile' is not defined


How to solve this problem?

Thank you!


From steve at pearwood.info  Thu Mar  6 03:14:45 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 06 Mar 2014 08:14:45 GMT
Subject: NameError: name 'pyver' is not defined
References: <be63ef8b-c37b-4cbb-93ac-edb72f64aa41@googlegroups.com>
Message-ID: <53182e74$0$2923$c3e8da3$76491128@news.astraweb.com>

On Wed, 05 Mar 2014 22:53:46 -0800, ?????? ???? wrote:

> Hello,
> 
> We have python 2.6 & 3.2 installed on Sun solaris. When running py
> utility, we get the below error:
> 
> "NameError: global name 'execfile' is not defined"

Sounds like you are accidentally running a script intended for Python2.6 
under Python3.2 instead.

execfile is removed from 3.2, so you need to either edit the script to 
update it for 3.2, or you need to make sure you are running it under 2.6. 

Do you need help with that?



-- 
Steven


From nad at acm.org  Thu Mar  6 03:26:34 2014
From: nad at acm.org (Ned Deily)
Date: Thu, 06 Mar 2014 00:26:34 -0800
Subject: NameError: name 'pyver' is not defined
References: <be63ef8b-c37b-4cbb-93ac-edb72f64aa41@googlegroups.com>
Message-ID: <nad-C4D344.00263406032014@news.gmane.org>

In article <be63ef8b-c37b-4cbb-93ac-edb72f64aa41 at googlegroups.com>,
 ?AIOE??OE?I <shulamitmi3 at gmail.com> wrote:
> We have python 2.6 & 3.2 installed on Sun solaris.
> When running py utility, we get the below error:
> 
> "NameError: global name 'execfile' is not defined"
> 
> 
> > p4convert-cvs.py
> EXCEPTION: [Errno 17] File exists: './LOGS'
> Traceback (most recent call last):
>   File "p4convert-cvs.py", line 134, in <module>
>     cvstop4lib.readconfig(configfile=args.config)
>   File "/bzqchome/bzq/ccbzq/mb_ccbzq/Perforce/p4convert/cvstop4lib.py", line 
>   61, in readconfig
>     execfile(configfile,globals()) # read in the config file - must be valid 
>     Python, evaluated in the context of this file
> NameError: global name 'execfile' is not defined

execfile() no long exists in Python 3 so chances are you are trying to 
run a Python 3 program with Python 2.  Try running the script explicitly 
under Python 2:

  python2.6 p4convert-cvs.py

You may have inadvertently done a "make install" with Python 3.2 that 
has created a link from "python" to "python3.2".  Later versions of 
Python 3 are a little more careful about reserving "python" for Python 2 
and "python3" for Python 3, although some distributions (notably Arch 
Linux) do it differently.

-- 
 Ned Deily,
 nad at acm.org



From nad at acm.org  Thu Mar  6 03:30:40 2014
From: nad at acm.org (Ned Deily)
Date: Thu, 06 Mar 2014 00:30:40 -0800
Subject: NameError: name 'pyver' is not defined
References: <be63ef8b-c37b-4cbb-93ac-edb72f64aa41@googlegroups.com>
 <nad-C4D344.00263406032014@news.gmane.org>
Message-ID: <nad-6B83B6.00304006032014@news.gmane.org>

In article <nad-C4D344.00263406032014 at news.gmane.org>,
 Ned Deily <nad at acm.org> wrote:
> execfile() no long exists in Python 3 so chances are you are trying to 
> run a Python 3 program with Python 2.  Try running the script explicitly 
> under Python 2:

Er, "trying to run a Python 2 program with Python 3", of course.

-- 
 Ned Deily,
 nad at acm.org



From shulamitmi3 at gmail.com  Thu Mar  6 03:36:56 2014
From: shulamitmi3 at gmail.com (=?UTF-8?B?16nXldec157XmdeqINee15nXqNec?=)
Date: Thu, 6 Mar 2014 00:36:56 -0800 (PST)
Subject: NameError: name 'pyver' is not defined
In-Reply-To: <mailman.7861.1394094410.18130.python-list@python.org>
References: <be63ef8b-c37b-4cbb-93ac-edb72f64aa41@googlegroups.com>
 <mailman.7861.1394094410.18130.python-list@python.org>
Message-ID: <61dc1068-866f-4f9c-9765-1ba4a0341580@googlegroups.com>

?????? ??? ?????, 6 ???? 2014 10:26:34 UTC+2, ??? Ned Deily: > In article <be63ef8b-c37b-4cbb-93ac-edb72f64aa41 at googlegroups.com>, ?AIOE??OE?I <shulamitmi3 at gmail.com> wrote: > We have python 2.6 & 3.2 installed on Sun solaris. > When running py utility, we get the below error: > > "NameError: global name 'execfile' is not defined" > > > > p4convert-cvs.py > EXCEPTION: [Errno 17] File exists: './LOGS' > Traceback (most recent call last): > File "p4convert-cvs.py", line 134, in <module> > cvstop4lib.readconfig(configfile=args.config) > File "/bzqchome/bzq/ccbzq/mb_ccbzq/Perforce/p4convert/cvstop4lib.py", line > 61, in readconfig > execfile(configfile,globals()) # read in the config file - must be valid > Python, evaluated in the context of this file > NameError: global name 'execfile' is not defined execfile() no long exists in Python 3 so chances are you are trying to run a Python 3 program with Python 2. Try running the script explicitly under Python 2: python2.6 p4convert-cvs.py You may have inadvertently done a "make install" with Python 3.2 that has created a link from "python" to "python3.2". Later versions of Python 3 are a little more careful about reserving "python" for Python 2 and "python3" for Python 3, although some distributions (notably Arch Linux) do it differently. -- Ned Deily, nad at acm.org thanks for your help! I tried first to run the script under 2.6 version, but than the "argparse" was missing. I couldn't find python 2.7 for unix download.


From shulamitmi3 at gmail.com  Thu Mar  6 03:40:57 2014
From: shulamitmi3 at gmail.com (=?UTF-8?B?16nXldec157XmdeqINee15nXqNec?=)
Date: Thu, 6 Mar 2014 00:40:57 -0800 (PST)
Subject: NameError: name 'pyver' is not defined
In-Reply-To: <mailman.7861.1394094410.18130.python-list@python.org>
References: <be63ef8b-c37b-4cbb-93ac-edb72f64aa41@googlegroups.com>
 <mailman.7861.1394094410.18130.python-list@python.org>
Message-ID: <c34565dc-276d-42e1-87c3-12302e098f76@googlegroups.com>

I tried first to run the script under 2.6 version, but than the "argparse" was missing. I couldn't find python 2.7 for unix download


From pavan.rikhi at gmail.com  Thu Mar  6 03:53:40 2014
From: pavan.rikhi at gmail.com (Pavan Rikhi)
Date: Thu, 6 Mar 2014 03:53:40 -0500
Subject: NameError: name 'pyver' is not defined
In-Reply-To: <be63ef8b-c37b-4cbb-93ac-edb72f64aa41@googlegroups.com>
References: <be63ef8b-c37b-4cbb-93ac-edb72f64aa41@googlegroups.com>
Message-ID: <20140306085340.GA1083@Lucy.acorn>

On Wed, Mar 05, 2014 at 10:53:46PM -0800, ?????? ???? wrote:
> execfile(configfile,globals())

You could replace the above line in cvstop4lib.py with the following:

    exec(open(configfile).read(), globals())
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From c.candide at laposte.net  Thu Mar  6 06:34:49 2014
From: c.candide at laposte.net (candide)
Date: Thu, 6 Mar 2014 03:34:49 -0800 (PST)
Subject: Ternary operator associativity
Message-ID: <f3bd8da6-dc2e-4b05-b50b-3a2c9d825367@googlegroups.com>

According to the official documentation, the ternary operator has left-to-right associativity :

-------------------
Operators in the same box group left to right (except for comparisons, including tests, which all have the same precedence and chain from left to right -- see section Comparisons -- and exponentiation, which groups from right to left).
-------------------


Nevertheless, the ternary operator grouping seems to be from right to left, compare :


>>> p = 0 if 1 else 0 if 0 else 1
>>> p
0
>>> left_to_right = (0 if 1 else 0) if 0 else 1
>>> right_to_left = 0 if 1 else (0 if 0 else 1)
>>> p == left_to_right
False
>>> p == right_to_left
True
>>> 


From oscar.j.benjamin at gmail.com  Thu Mar  6 07:27:16 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Thu, 6 Mar 2014 12:27:16 +0000
Subject: Working with the set of real numbers
In-Reply-To: <lf76nv$3s9$1@ger.gmane.org>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
 <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>
 <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>
 <lf5mr8$ttr$1@ger.gmane.org>
 <CAHVvXxQo2-B8t+xmG04Awr1Z9V0o+w9az5UtpSEY=AmaW9pe0A@mail.gmail.com>
 <lf76nv$3s9$1@ger.gmane.org>
Message-ID: <CAHVvXxTVZy5wyp5_VZT4PUTDd+zOnK6zzrAgE4qo42e3Oqvzcg@mail.gmail.com>

On 5 March 2014 12:57, Dave Angel <davea at davea.name> wrote:
>  Oscar Benjamin <oscar.j.benjamin at gmail.com> Wrote in message:
>> On 4 March 2014 23:20, Dave Angel <davea at davea.name> wrote:
>>>
>>> On the assumption that division by 2 is very fast,  and that a
>>>  general multiply isn't too bad, you could improve on Newton by
>>>  observing that the slope is 2.
>>>
>>>    err = n - guess * guess
>>>     guess += err/2
>>
>> I gues you mean like this:
>>
>> def sqrt(n):
>>     err = guess = 1
>>     while err > 1e-10:
>>         err = n - guess * guess
>>         guess += err/2
>>     return guess
>>
>> This requires log2(10)*N iterations to get N digits.
>
> No idea how you came up with that,  but I see an error in my
>  stated algorithm,  which does surely penalize it. The slope isn't
>  2, but 2x.  So the line should have been
>         guess += err/(2*guess)

Ah, now I understand. This is the same algorithm that Chris posted
which in turn is the same as the one that I had previously posted: all
three are just using Newton's method.

Newton's method uses the slope argument to find a root of f(x) i.e. an
x0 such that f(x0) = 0. We start with a guess x[n]. We then find the
value of the function f(x[n]) and slope fp(x[n]) and extrapolating to
the point where f(x) hits the x-axis we find an improved estimate with

    x[n+1] = x[n] - f(x[n]) / fp(x[n])

In our case f(x) = x**2 - y and so fp(x) = 2*x which gives

    x[n+1] = x[n] - (x[n]**2 - y) / (2*x[n])

and after rearranging we can express this as

    x[n+1] = (x[n] + y/x[n]) / 2.

So my loop

        while x ** 2 - y > x * eps:
            x = (x + y/x) / 2

and Chris' loop:

    while abs(guess1-guess2) > epsilon:
        guess1 = n/guess2
        guess2 = (guess1 + guess2)/2

and now your loop

    while err > 1e-10:
        err = n - guess * guess
        guess += err/(2 * guess)

are all performing the same basic algorithm. The only significant
difference is that mine tests for a relative error condition where as
the other two test for absolute error. This means that it will still
converge to an answer with the correct precision even when the root is
large e.g. sqrt(1e100). The other two are susceptible to infinite
loops in this case.

> Now if you stop the loop after 3 iterations (or use some other
>  approach to get a low-precision estimate,  then you can calculate
>  scale = 1/(2*estimate)
>
> and then for remaining iterations,
>         guess += err *scale

Fair enough. That's a reasonable suggestion for improvement. This is
often known as the "modified Newton's method". For lack of a better
reference see here:
http://math.stackexchange.com/questions/645088/modified-newtons-method

Using an approximate slope to avoid division can be a significant
optimisation. This is especially true when using the multidimensional
generalisation of Newton's method since in this case the division is
replaced with solving a system of linear equations (vastly more
expensive). However as noted in that stackexchange answer the use of
an approximate slope prevents quadratic convergence so in the
asymptotic case where we want large numbers of digits it can be much
slower.

Actually it's worse than that since we are guaranteed to converge to
an incorrect answer. The update step x = (x + y/x) / 2 will converge
when x^2 = y but we replace it with x = (x + y/x0)/2 where x0 is near
to the true root. This will converge when x == (x + y/x0)/2 i.e. when
x = y/x0 which is not the correct answer (and can be computed without
a loop in any case). It's possible to fix that by alternating between
steps where we improve our estimate  of the slope and steps where we
use that estimate for refinement but I don't think that the advantage
of not using division counts against the loss of quadratic convergence
once we get to more than 10s of digits.

You can compare them yourself with this code:

def sqrt1(y, prec=1000):
    '''Solve x**2 = y'''
    assert y > 0
    eps = D(10) ** -(prec + 5)
    x = D(y)
    with localcontext() as ctx:
        ctx.prec = prec + 10
        while abs(x ** 2 - y) > x * eps:
            x = (x + y/x) / 2
    return x

def sqrt2(y, prec=1000):
    '''Solve x**2 = y'''
    assert y > 0
    eps = D(10) ** -(prec + 5)
    x = D(y)
    with localcontext() as ctx:
        ctx.prec = prec + 10
        for n in range(7):
            x = (x + y/x) / 2
        x0r = 1 / x
        while abs(x ** 2 - y) > x * eps:
            err = x**2 - y
            err2 = x - x0r * y
            x = (x + x0r * y) / 2
    return x

sqrt2(2) goes into an infinite loop at an error level of ~1e-100 (the
exact point where this happens depends on how many warmup iterations
it uses).

[snip]
>>
>> This method works out much slower than Newton with division at 10000
>> digits: 40s (based on a single trial) vs 80ms (timeit result).
>
> Well considering you did not special-case the divide by 2, I'm not
>  surprised it's slower.

Multiplying by D('0.5') instead of dividing by 2 makes no measurable
difference to the timings. I don't know whether that's because it's
already special-cased by Decimal or just that the performance costs
don't match up in the same way for the multiprecision algorithms (when
the divisor is a single digit number).


Oscar


From rustompmody at gmail.com  Thu Mar  6 07:43:00 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 6 Mar 2014 04:43:00 -0800 (PST)
Subject: Program Python
In-Reply-To: <mailman.7841.1394055738.18130.python-list@python.org>
References: <mailman.7841.1394055738.18130.python-list@python.org>
Message-ID: <9eeb3673-f629-4b43-9b6b-d8510d88333e@googlegroups.com>

On Thursday, March 6, 2014 3:11:10 AM UTC+5:30, Luciano Trespidi wrote:
> I'm very grateful if anyone can helpme to find a good program to develop in python lenguage.
> Thanks

> Inviato da:
> Ernesto Luciano Trespidi
> Email: keplero1...
> Tel.  32...

Hi and welcome

Just a small warning in addition to what others have said
Information such as your email and phone posted above will be
publicly available on the net.  You perhaps dont want that??


From python.list at tim.thechases.com  Thu Mar  6 08:09:40 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Thu, 6 Mar 2014 07:09:40 -0600
Subject: Python programming
In-Reply-To: <531812e0$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <98df529b-afe3-4f96-92ff-ff6e936d3dda@googlegroups.com>
 <531812e0$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <20140306070940.4d719e9f@bigbox.christie.dr>

On 2014-03-06 06:17, Steven D'Aprano wrote:
> On Wed, 05 Mar 2014 20:19:56 -0800, Beowulf wrote:
> 
> > Once you master one language it is easy to understand other.  
> 
> Depends on the languages. Learning Forth doesn't make it easier to
> learn Perl. Learning Pascal doesn't make Smalltalk easier.

And despite having a couple dozen languages worth of (varying levels
of) experience under my belt, Prolog still feels to me like
programming by epiphany.

-tkc





From rosuav at gmail.com  Thu Mar  6 08:16:24 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 00:16:24 +1100
Subject: Working with the set of real numbers
In-Reply-To: <CAHVvXxTVZy5wyp5_VZT4PUTDd+zOnK6zzrAgE4qo42e3Oqvzcg@mail.gmail.com>
References: <8e4c1ab1-e65d-483f-ad9d-6933ae2052c3@googlegroups.com>
 <CAPTjJmo4qD2B7isr8yAK2t+22KqwaoFrT5b5U66mYe+VgwDkWA@mail.gmail.com>
 <85r478bv99.fsf_-_@benfinney.id.au>
 <mailman.6735.1392194885.18130.python-list@python.org>
 <53153e66$0$24931$e4fe514c@dreader36.news.xs4all.nl>
 <mailman.7687.1393902132.18130.python-list@python.org>
 <59dd57ad-39b0-4c71-a58e-b4ae6517b385@googlegroups.com>
 <mailman.7689.1393904790.18130.python-list@python.org>
 <53156a42$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7696.1393914922.18130.python-list@python.org>
 <87iortoic0.fsf@elektro.pacujo.net>
 <CAPTjJmpKASpOEscAjVDC5bpqK1kQt3rLTmCmUp-s4Ov2go6d2g@mail.gmail.com>
 <CAHVvXxR2TQzoiedi9Dns9RTMr_HVE_A5_tVWPGq_PmQ7zeV9Qw@mail.gmail.com>
 <CAPTjJmocK7Wpi765JKiNxEtquabm4No9GWomHv-vX7auFkqZ=w@mail.gmail.com>
 <CAHVvXxTSFnzZbRH2=xRr+yxidmTrUyCYsFPABOQBp3U5_2_-tQ@mail.gmail.com>
 <lf5mr8$ttr$1@ger.gmane.org>
 <CAHVvXxQo2-B8t+xmG04Awr1Z9V0o+w9az5UtpSEY=AmaW9pe0A@mail.gmail.com>
 <lf76nv$3s9$1@ger.gmane.org>
 <CAHVvXxTVZy5wyp5_VZT4PUTDd+zOnK6zzrAgE4qo42e3Oqvzcg@mail.gmail.com>
Message-ID: <CAPTjJmoR3P67fFnq3i2pmi5D9d8TbrvPOEyGD-ypVNbeUMOXmA@mail.gmail.com>

On Thu, Mar 6, 2014 at 11:27 PM, Oscar Benjamin
<oscar.j.benjamin at gmail.com> wrote:
> So my loop
>
>         while x ** 2 - y > x * eps:
>             x = (x + y/x) / 2
>
> and Chris' loop:
>
>     while abs(guess1-guess2) > epsilon:
>         guess1 = n/guess2
>         guess2 = (guess1 + guess2)/2
>
> and now your loop
>
>     while err > 1e-10:
>         err = n - guess * guess
>         guess += err/(2 * guess)
>
> are all performing the same basic algorithm. The only significant
> difference is that mine tests for a relative error condition where as
> the other two test for absolute error. This means that it will still
> converge to an answer with the correct precision even when the root is
> large e.g. sqrt(1e100). The other two are susceptible to infinite
> loops in this case.

This is one place where I find the REXX 'numeric fuzz' setting to be a
useful trick. The definition is that, whenever two numbers are
compared for equality, the 'numeric digits' setting is effectively
reduced by the fuzz for that comparison. So let's say we're
calculating to a precision of 100 digits ('numeric digits 100'). You
could then code the loop as "do until guess1=guess2", with a numeric
fuzz of, say, 2. That'll give you 98 digits of accuracy, *regardless
of scale*. It's like setting epsilon to "whatever would be 1e-98 if we
were working with numbers between 0 and 1", more or less. A sliding
epsilon.

ChrisA


From christoff.kok at ex-mente.co.za  Thu Mar  6 08:19:52 2014
From: christoff.kok at ex-mente.co.za (Christoff Kok)
Date: Thu, 6 Mar 2014 05:19:52 -0800 (PST)
Subject: Struggling to create an extension wrapping a 3rd party dll
In-Reply-To: <4f813ff8-d0c8-4370-b669-5484f3dcd467@googlegroups.com>
References: <4f813ff8-d0c8-4370-b669-5484f3dcd467@googlegroups.com>
Message-ID: <12944247-3222-4834-80c4-9ad6b4143ff9@googlegroups.com>

On Wednesday, 5 March 2014 09:10:33 UTC+2, Christoff Kok  wrote:
> Hi,
> 
> 
> 
> We are trying to wrap a 3rd party dll (written in C) to access it through python.
> 
> The dll has a .lib .c and a .h file with it. We are accessing the dll through the .c file.
> 
> 
> 
> Outisde of the extension (running as a console application), the code works without an issue. without the 3rd party dll, the python extension works without an issue. The issue comes in when trying combine the third party dll with the python extension.
> 
> 
> 
> Here is the distutil installation script
> 
> 
> 
> ################ Setup.py ################################
> 
> 
> 
> from distutils.core import setup, Extension
> 
> 
> 
> chemAppPython_mod = Extension('chemAppPython', sources = ['chemAppPython.c', 'cacint.c'], libraries=['ca_vc_opt_e'], depends = ['cacint.h'])
> 
> 
> 
> setup(name = "chemAppPython",
> 
>     version = "1.0",
> 
>     description = "The ChemnApp Python module",
> 
>     ext_modules = [chemAppPython_mod],
> 
> 	data_files = [('',['ca_vc_e.dll'])]
> 
> )
> 
> 
> 
> ##########################################################
> 
> 
> 
> * ca_vc_opt_e.lib and ca_vc_e.dll is the library containing the third party methods we want to access.
> 
> 
> 
> * cacint.h and cacint.c is the files acting as an interface to the ca_vc_opt_e.lib and ca_vc_e.dll.
> 
> * chemAppPython.c is file containing the code wrapping the calls to the cacint.c (and in effect, the third party dll)
> 
> 
> 
> The errors we are receiving are:
> 
> C:\Python33\source\Python-3.3.4\ChemAppPython>setup.py install
> 
> running install
> 
> running build
> 
> running build_ext
> 
> building 'chemAppPython' extension
> 
> creating build
> 
> creating build\temp.win-amd64-3.3
> 
> creating build\temp.win-amd64-3.3\Release
> 
> C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -IC:\Python33\include -IC:\Python33\include /TcchemAppPython.c /Fobuild\temp.win-amd64-3.3\Release\chemAppPython.obj
> 
> chemAppPython.c
> 
> C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -IC:\Python33\include -IC:\Python33\include /Tccacint.c /Fobuild\temp.win-amd64-3.3\Release\cacint.obj
> 
> cacint.c
> 
> cacint.c(357) : warning C4267: 'function' : conversion from 'size_t' to 'long', possible loss of data
> 
> cacint.c(390) : warning C4267: 'function' : conversion from 'size_t' to 'long', possible loss of data
> 
> .
> 
> .
> 
> . (some more of the same warning message for different functions.)
> 
> .
> 
> cacint.c(619) : warning C4996: 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
> 
> .
> 
> .
> 
> . 
> 
> . (some more of the same warning message at different positions in code.)
> 
> .
> 
> creating build\lib.win-amd64-3.3
> 
> C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\link.exe /DLL /nologo /INCREMENTAL:NO /LIBPATH:C:\Python33\libs /LIBPATH:C:\Python33\PCbuild\amd64 ca_vc_opt_e.lib /EXPORT:PyInit_chemAppPython build\temp.win-amd64-3.3\Release\chemAppPython.obj build\temp.win-amd64-3.3\Rele
> 
> chemAppPython.obj : warning LNK4197: export 'PyInit_chemAppPython' specified multiple times; using first specification
> 
>    Creating library build\temp.win-amd64-3.3\Release\chemAppPython.lib and object build\temp.win-amd64-3.3\Release\chemAppPython.exp
> 
> cacint.obj : error LNK2019: unresolved external symbol TQINI referenced in function tqini
> 
> cacint.obj : error LNK2019: unresolved external symbol TQOPEN referenced in function tqopen
> 
> .
> 
> .
> 
> . (a lot more of them, for different methods. Again, it builds and runs fine in the console app host application.)
> 
> .
> 
> build\lib.win-amd64-3.3\chemAppPython.pyd : fatal error LNK1120: 74 unresolved externals
> 
> error: command '"C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\link.exe"' failed with exit status 1120
> 
> 
> 
> 
> 
> Help would really be appreciated.

Ok, I have progress. I can run the extension manually, without deploying with distutil using a the python source code build and running it from the extensions Debug/Release folder. We need to deploy the extension though so getting it right to work with distutil is very important. Still getting the exact same issue as mentioned in my first post.

It seems that the 'ca_vc_opt_e.lib' library is not linked in the module.


From invalid at invalid.invalid  Thu Mar  6 09:49:09 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Thu, 6 Mar 2014 14:49:09 +0000 (UTC)
Subject: Python programming
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <98df529b-afe3-4f96-92ff-ff6e936d3dda@googlegroups.com>
 <lf8udn$eag$1@dont-email.me> <roy-9164B8.23512805032014@news.panix.com>
Message-ID: <lfa1t5$eh3$1@reader1.panix.com>

On 2014-03-06, Roy Smith <roy at panix.com> wrote:
> In article <lf8udn$eag$1 at dont-email.me>,
>  Dan Sommers <dan at tombstonezero.net> wrote:
>
>> On Wed, 05 Mar 2014 20:19:56 -0800, Beowulf wrote:
>> 
>> > Once you master one language it is easy to understand other ...
>> 
>> Once you master one language, the next one is hard.  After that, they
>> get easier.
>
> And then you get to PHP.

Yep, it's a real mess.  Both the language and the room you're in when
your head finally explodes.

-- 
Grant Edwards               grant.b.edwards        Yow! Th' MIND is the Pizza
                                  at               Palace of th' SOUL
                              gmail.com            


From invalid at invalid.invalid  Thu Mar  6 09:52:26 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Thu, 6 Mar 2014 14:52:26 +0000 (UTC)
Subject: Python programming
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <98df529b-afe3-4f96-92ff-ff6e936d3dda@googlegroups.com>
 <531812e0$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7865.1394111358.18130.python-list@python.org>
Message-ID: <lfa23a$eh3$2@reader1.panix.com>

On 2014-03-06, Tim Chase <python.list at tim.thechases.com> wrote:
> On 2014-03-06 06:17, Steven D'Aprano wrote:
>> On Wed, 05 Mar 2014 20:19:56 -0800, Beowulf wrote:
>> 
>> > Once you master one language it is easy to understand other.  
>> 
>> Depends on the languages. Learning Forth doesn't make it easier to
>> learn Perl. Learning Pascal doesn't make Smalltalk easier.
>
> And despite having a couple dozen languages worth of (varying levels
> of) experience under my belt, Prolog still feels to me like
> programming by epiphany.

Back when I was in school, Lisp and Prolog were the hardest to grok. I
eventually "got" Lisp (well, I actually "got" Scheme, and I think I
could now "get" Lisp if I tried).  Prolog is definitely the odd one of
the dozen or two languages I've learned -- and I even wrote a small
expert system in Prolog as a project for a software engineering class.

-- 
Grant Edwards               grant.b.edwards        Yow! I think my career
                                  at               is ruined!
                              gmail.com            


From fabiofz at gmail.com  Thu Mar  6 10:42:02 2014
From: fabiofz at gmail.com (Fabio Zadrozny)
Date: Thu, 6 Mar 2014 12:42:02 -0300
Subject: Diagnose a segfault in ipython/readline
In-Reply-To: <1779169.vC7H4N7YzS@felix-arch>
References: <2114014.zHAFJyoHbS@felix-arch>
 <nad-F1D106.20153105032014@news.gmane.org>
 <1779169.vC7H4N7YzS@felix-arch>
Message-ID: <CANXBEFqxv-a6cxUk9CxLtw8CLOSAJXrCrd0zLShvxv-wLVPVqA@mail.gmail.com>

On Thu, Mar 6, 2014 at 3:11 AM, Felix Yan <felixonmars at gmail.com> wrote:

> On Wednesday, March 05, 2014 20:15:31 Ned Deily wrote:
> > The current
> > assumption is that Python 2.7.6+, 3.3.5, and 3.4.0 have no problems with
> > readline 6.3.
>
> Thank you.
>
> I just gave a try to 3.4.0b2 with readline 6.3, and still get the same
> segfault. Not sure the version is new enough though.
>
> Also we reported the problem on readline mailing list first, so if they
> end up
> thinking there's something that python need to fix, I'll open a bug on the
> Python bug tracker.
>
> Thanks again!
>
>
Just a note here (which may or may not work for your case), but you could
try using the faulthandler module to see if it can give you a stack trace
you can work with...

Cheers,

Fabio
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From bv8bv8bv8 at gmail.com  Thu Mar  6 11:58:26 2014
From: bv8bv8bv8 at gmail.com (BV BV)
Date: Thu, 6 Mar 2014 08:58:26 -0800 (PST)
Subject: Who Invented the Trinity?
Message-ID: <c4b06b15-d875-4843-9b73-d5bf1de5f10b@googlegroups.com>

Who Invented the Trinity?

1-How the concept of the Trinity was introduced into the Christian doctrine.
2-How the injected doctrine of the trinity remained part of the beliefs of the Christians and how Islam defines God.

 
What is the source of the Christian concept of the Trinity?
The three monotheistic religions - Judaism, Christianity, and Islam - all purport to share one fundamental concept: belief in God as the Supreme Being, the Creator and Sustainer of the Universe.  Known as "tawhid" in Islam, this concept of the Oneness of God was stressed by Moses in a Biblical passage known as the "Shema", or the Jewish creed of faith:

"Hear, O Israel: The Lord our God is one Lord." (Deuteronomy 6:4)

It was repeated word-for-word approximately 1500 years later by Jesus, when he said:

"...The first of all the commandments is, Hear, O Israel; the Lord our God is one Lord." (Mark 12:29)

Muhammad came along approximately 600 years later, bringing the same message again:

"And your God is One God: there is no God but He..." (Quran 2:163)

Christianity has digressed from the concept of the Oneness of God, however, into a vague and mysterious doctrine that was formulated during the fourth century.  This doctrine, which continues to be a source of controversy both within and outside the Christian religion, is known as the Doctrine of the Trinity.  Simply put, the Christian doctrine of the Trinity states that God is the union of three divine persons - the Father, the Son and the Holy Spirit - in one divine being.

If that concept, put in basic terms, sounds confusing, the flowery language in the actual text of the doctrine lends even more mystery to the matter:

"...we worship one God in Trinity, and Trinity in Unity... for there is one Person of the Father, another of the Son, another of the Holy Ghost is all one... they are not three gods, but one God... the whole three persons are co-eternal and co-equal... he therefore that will be saved must thus think of the Trinity..." (excerpts from the Athanasian Creed)

Let's put this together in a different form: one person, God the Father, plus one person, God the Son, plus one person, God the Holy Ghost, equals one person, God the What?  Is this English or is this gibberish?

It is said that Athanasius, the bishop who formulated this doctrine, confessed that the more he wrote on the matter, the less capable he was of clearly expressing his thoughts regarding it.

How did such a confusing doctrine get its start?

Trinity in the Bible
References in the Bible to a Trinity of divine beings are vague, at best.

In Matthew 28:19, we find Jesus telling his disciples to go out and preach to all nations.  While this "Great Commission" does make mention of the three persons who later become components of the Trinity, the phrase "...baptizing them in the name of the Father, and of the Son, and of the Holy Ghost" is quite clearly an addition to Biblical text - that is, not the actual words of Jesus - as can be seen by two factors:

1)    baptism in the early Church, as discussed by Paul in his letters, was done only in the name of Jesus; and

2)    the "Great Commission" was found in the first gospel written, that of Mark, bears no mention of Father, Son and/or Holy Ghost - see Mark 16:15.

The only other reference in the Bible to a Trinity can be found in the Epistle of 1 John 5:7.  Biblical scholars of today, however, have admitted that the phrase:

"...there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one"

...is definitely a "later addition" to Biblical text, and it is not found in any of today's versions of the Bible.

It can, therefore, be seen that the concept of a Trinity of divine beings was not an idea put forth by Jesus or any other prophet of God.  This doctrine, now subscribed to by Christians all over the world, is entirely man-made in origin.

The Doctrine Takes Shape
While Paul of Tarsus, the man who could rightfully be considered the true founder of Christianity, did formulate many of its doctrines, that of the Trinity was not among them.  He did, however, lay the groundwork for such when he put forth the idea of Jesus being a "divine Son".  After all, a Son does need a Father, and what about a vehicle for God's revelations to man?  In essence, Paul named the principal players, but it was the later Church people who put the matter together.

Tertullian, a lawyer and presbyter of the third-century Church in Carthage, was the first to use the word "Trinity" when he put forth the theory that the Son and the Spirit participate in the being of God, but all are of one being of substance with the Father.

A Formal Doctrine is Drawn Up
When controversy over the matter of the Trinity blew up in 318 between two church men from Alexandria - Arius, the deacon, and Alexander, his bishop - Emperor Constantine stepped into the fray.

Although Christian dogma was a complete mystery to him, he did realize that a unified church was necessary for a strong kingdom.  When negotiation failed to settle the dispute, Constantine called for the first ecumenical council in Church history in order to settle the matter once and for all.

Six weeks after the 300 bishops first gathered at Nicea in 325, the doctrine of the Trinity was hammered out.  The God of the Christians was now seen as having three essences, or natures, in the form of the Father, the Son, and the Holy Spirit.

The Church Puts its Foot Down
The matter was far from settled, however, despite high hopes for such on the part of Constantine.  Arius and the new bishop of Alexandria, a man named Athanasius, began arguing over the matter even as the Nicene Creed was being signed; "Arianism" became a catch-word from that time onward for anyone who didn't hold to the doctrine of the Trinity.

It wasn't until 451, at the Council of Chalcedon that, with the approval of the Pope, the Nicene/Constantinople Creed was set as authoritative.  Debate on the matter was no longer tolerated; to speak out against the Trinity was now considered blasphemy, and such earned stiff sentences that ranged from mutilation to death.  Christians now turned on Christians, maiming and slaughtering thousands because of a difference of opinion.

Debate Continues
Brutal punishments and even death did not stop the controversy over the doctrine of the Trinity, however, and the said controversy continues even today.

The majority of Christians, when asked to explain this fundamental doctrine of their faith, can offer nothing more than "I believe it because I was told to do so." It is explained away as "mystery" - yet the Bible says in 1 Corinthians 14:33 that:

"... God is not the author of confusion ..."

The Unitarian denomination of Christianity has kept alive the teachings of Arius in saying that God is one; they do not believe in the Trinity.  As a result, mainstream Christians abhor them, and the National Council of Churches has refused their admittance.  In Unitarianism, the hope is kept alive that Christians will someday return to the preachings of Jesus:

"... Thou shalt worship the Lord thy God, and Him only shalt thou serve." (Luke 4:8)

Islam and the Matter of the Trinity
While Christianity may have a problem defining the essence of God, such is not the case in Islam:

"They do blaspheme who say: Allah is one of three in a Trinity, for there is no god except One God" (Quran 5:73)

It is worth noting that the Arabic language Bible uses the name "Allah" as the name of God.

Suzanne Haneef, in her book What Everyone Should Know About Islam and Muslims (Library of Islam, 1985), puts the matter quite succinctly when she says:

"But God is not like a pie or an apple which can be divided into three thirds which form one whole; if God is three persons or possesses three parts, He is assuredly not the Single, Unique, Indivisible Being which God is and which Christianity professes to believe in." [1]

Looking at it from another angle, the Trinity designates God as being three separate entities - the Father, the Son and the Holy Spirit.  If God is the Father and also the Son, He would then be the Father of Himself because He is His own Son.  This is not exactly logical.

Christianity claims to be a monotheistic religion.  Monotheism, however, has as its fundamental belief that God is One; the Christian doctrine of the Trinity - God being Three-in-One - is seen by Islam as a form of polytheism.  Christians don't revere just One God, they revere three.

This is a charge not taken lightly by Christians, however.  They, in turn, accuse the Muslims of not even knowing what the Trinity is, pointing out that the Quran sets it up as Allah the Father, Jesus the Son, and Mary his mother.  While veneration of Mary has been a figment of the Catholic Church since 431 when she was given the title "Mother of God" by the Council of Ephesus, a closer examination of the verses in the Quran most often cited by Christians in support of their accusation, shows that the designation of Mary by the Quran as a "member" of the Trinity, is simply not true.

While the Quran does condemn both Trinitarianism (the Quran 4:171; 5:73) [2] and the worship of Jesus and his mother Mary (the Quran 5:116) [3], nowhere does it identify the actual three components of the Christian Trinity.  The position of the Quran is that WHO or WHAT comprises this doctrine is not important; what is important is that the very notion of a Trinity is an affront against the concept of One God.

In conclusion, we see that the doctrine of the Trinity is a concept conceived entirely by man; there is no sanction whatsoever from God to be found regarding the matter simply because the whole idea of a Trinity of divine beings has no place in monotheism.  In the Quran, God's Final Revelation to mankind, we find His stand quite clearly stated in a number of eloquent passages:

"... your God is One God: whoever expects to meet his Lord, let him work righteousness, and, in the worship of his Lord, admit no one as partner." (Quran 18:110)

"... take not, with God, another object of worship, lest you should be thrown into Hell, blameworthy and rejected." (Quran 17:39)

- because, as God tells us over and over again in a Message that is echoed throughout ALL His Revealed Scriptures:

"... I am your Lord and Cherisher: therefore, serve Me (and no other) ..." (Quran 21:92)

                                                              


[1] What Everyone Should Know About Islam and Muslims (Library of Islam, 1985) (pp. 183-184)
[2] "O People of the Scripture, do not commit excess in your religion or say about God except the truth.  The Messiah, Jesus, the son of Mary, was but a Messenger of God and His word which He directed to Mary and a soul [created at a command] from Him.  So believe in God and His messengers.  And do not say, 'Three'; desist--it is better for you.  Indeed, God is but one God.  Exalted is He above having a son.  To Him belongs whatever is in the heavens and whatever is on the earth.  And sufficient is God as Disposer of affairs." (Quran 4:171)
[3] "And [beware the Day] when God will say, 'O Jesus, Son of Mary, did you say to the people, 'Take me and my mother as deities besides God?'  'He will say, 'Exalted are You!  It was not for me to say that to which I have no right.  If I had said it, You would have known it.  You know what is within myself, and I do not know what is within Yourself.  Indeed, it is You who is Knower of the unseen.' (Quran 5:116)


http://www.islamhouse.com/428121/en/en/articles/Who_Invented_the_Trinity?


Thank you


From breamoreboy at yahoo.co.uk  Thu Mar  6 12:43:19 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 06 Mar 2014 17:43:19 +0000
Subject: Origin of 'self'
In-Reply-To: <1634feec-9f23-4f46-bd38-f5f6ef3b0113@googlegroups.com>
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
 <531426b8$0$2923$c3e8da3$76491128@news.astraweb.com>
 <1634feec-9f23-4f46-bd38-f5f6ef3b0113@googlegroups.com>
Message-ID: <lfac3i$o8v$1@ger.gmane.org>

On 06/03/2014 01:56, Westley Mart?nez wrote:
> Why did C++ use this? I don't really like this. It doesn't sound right. I think it's because I have trouble saying the th sound without getting my mouth full of spit.
>
> Thankfully you don't often need to use this in C++ like you do with self in Python.
>

You don't need to use self, you can call it anything you like, but 
you'll not be particularly popular if you do this.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From torriem at gmail.com  Thu Mar  6 12:47:25 2014
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 06 Mar 2014 10:47:25 -0700
Subject: Ternary operator associativity
In-Reply-To: <f3bd8da6-dc2e-4b05-b50b-3a2c9d825367@googlegroups.com>
References: <f3bd8da6-dc2e-4b05-b50b-3a2c9d825367@googlegroups.com>
Message-ID: <5318B4AD.9010508@gmail.com>

On 03/06/2014 04:34 AM, candide wrote:
> According to the official documentation, the ternary operator has left-to-right associativity :
> 
> -------------------
> Operators in the same box group left to right (except for comparisons, including tests, which all have the same precedence and chain from left to right -- see section Comparisons -- and exponentiation, which groups from right to left).
> -------------------
> 
> 
> Nevertheless, the ternary operator grouping seems to be from right to left, compare :

I was reading a blog about PHP the other day and it mentioned PHP was
the only language he knew of that had ternary operator precedence going
left to right.  All other languages use right to left.  So I assume that
Python also uses right to left and that the documentation is a bug.



From marko at pacujo.net  Thu Mar  6 12:46:15 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 06 Mar 2014 19:46:15 +0200
Subject: Origin of 'self'
References: <dc4f4ee0-8380-4141-97bd-99d6e67d5e2d@googlegroups.com>
 <531426b8$0$2923$c3e8da3$76491128@news.astraweb.com>
 <1634feec-9f23-4f46-bd38-f5f6ef3b0113@googlegroups.com>
Message-ID: <87pplzqkyg.fsf@elektro.pacujo.net>

Westley Mart?nez <anikom15 at gmail.com>:

> Thankfully you don't often need to use this in C++ like you do with
> self in Python.

Self pity is not attractive.


Marko


From breamoreboy at yahoo.co.uk  Thu Mar  6 12:46:50 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 06 Mar 2014 17:46:50 +0000
Subject: Reference
In-Reply-To: <5317c2d5$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <53144e8d$0$2149$426a74cc@news.free.fr>
 <1d1dfa1b-b715-4d8f-9c12-f0d3dc1a22c9@googlegroups.com>
 <85ppm3httu.fsf@benfinney.id.au> <lf2sjk$7d4$1@ger.gmane.org>
 <20140303155112.46e34ff8@bigbox.christie.dr>
 <mailman.7666.1393884138.18130.python-list@python.org>
 <87siqy7whs.fsf@elektro.pacujo.net>
 <53155c15$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.7693.1393910647.18130.python-list@python.org>
 <op.xb75g7ap5079vu@gnudebeest> <roy-A9E76C.21091704032014@news.panix.com>
 <164d209c-ba5e-449f-bc25-c27ebfb1fc0f@googlegroups.com>
 <5316b0dc$0$2923$c3e8da3$76491128@news.astraweb.com>
 <e1fc76f0-a7f4-4e04-8231-30d2b306e898@googlegroups.com>
 <53176cfe$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <87mwh475bc.fsf@elektro.pacujo.net>
 <mailman.7833.1394053296.18130.python-list@python.org>
 <87bnxk73gb.fsf@elektro.pacujo.net>
 <mailman.7837.1394054791.18130.python-list@python.org>
 <5317c2d5$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lfaca5$qts$1@ger.gmane.org>

On 06/03/2014 00:35, Steven D'Aprano wrote:
> On Thu, 06 Mar 2014 08:26:22 +1100, Chris Angelico wrote:
>
>> On Thu, Mar 6, 2014 at 8:14 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> When I talk about an object's memory address, I'm not referring to what
>>> might be revealed by gdb, for example. That is, I'm not talking about
>>> the process's virtual address space, nor am I talking about the
>>> physical address on the address bus. I can simply define that the
>>> object's memory address is whatever id() returns.
>>
>> Where's the complaints about circularity now? You're saying "But of
>> course id() returns the address, as long as we define the address as
>> 'whatever id() returns'.". Unimpeachably logical and utterly unhelpful.
>
> That last sentence is wrong. There is nothing logical about just making
> up arbitrary definitions in this way. He could invent *any* definition,
> each more ridiculous than the last:
>
> - it's the object's memory address;
>
> - it's the object's phone number;
>
> - it's the number of baby elephants killed by the object;
>
> - it's the number of intergalactic empires that are, even as we
>    speak, rushing to Earth to invade to gain possession of that
>    object;
>
> - it's the weight in metric tonnes of the electrons in the object;
>
>    (Not *actual* electrons of course, just these arbitrary inventions
>    of Marko's definition.)
>
> - it's the length measured in seconds of the bitterness of the
>    object's kidney;
>
>
> and of course:
>
> - the number of angels that can dance on the object.
>

You've missed the most obvious one, the number of words written on this 
mailing list about Python that are completely wrong.  That number is far 
larger than the sum of all your definitions given above, where sum has 
the usual maths definition and not Marko's.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From tjreedy at udel.edu  Thu Mar  6 13:52:46 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 06 Mar 2014 13:52:46 -0500
Subject: Ternary operator associativity
In-Reply-To: <f3bd8da6-dc2e-4b05-b50b-3a2c9d825367@googlegroups.com>
References: <f3bd8da6-dc2e-4b05-b50b-3a2c9d825367@googlegroups.com>
Message-ID: <lfag5u$c9s$1@ger.gmane.org>

On 3/6/2014 6:34 AM, candide wrote:
> According to the official documentation, the ternary operator has
> left-to-right associativity :

The proper terms is 'conditional expression', which goes back to "The C 
Programming Language" (K&R). There are many unary operators, many binary 
operators, and there could be other ternary operators.

> ------------------- Operators in the same box group left to right
> (except for comparisons, including tests, which all have the same
> precedence and chain from left to right -- see section Comparisons --
> and exponentiation, which groups from right to left).
> -------------------
>
> Nevertheless, the ternary operator grouping seems to be from right to
> left, compare :
>
>>>> p = 0 if 1 else 0 if 0 else 1 p
> 0
>>>> left_to_right = (0 if 1 else 0) if 0 else 1
 >>>> right_to_left = 0 if 1 else (0 if 0 else 1)
 >>>> p == left_to_right
> False
>>>> p == right_to_left
> True

This behavior is specified in the grammar as given in the C-E section.

The doc is also inconsistent about evaluation order and precedence. I 
opened  http://bugs.python.org/issue20859 .

-- 
Terry Jan Reedy



From python.list at tim.thechases.com  Thu Mar  6 13:59:58 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Thu, 6 Mar 2014 12:59:58 -0600
Subject: Ternary operator associativity
In-Reply-To: <f3bd8da6-dc2e-4b05-b50b-3a2c9d825367@googlegroups.com>
References: <f3bd8da6-dc2e-4b05-b50b-3a2c9d825367@googlegroups.com>
Message-ID: <20140306125958.31e096f8@bigbox.christie.dr>

On 2014-03-06 03:34, candide wrote:
> According to the official documentation, the ternary operator has
> left-to-right associativity 
>
> >>> left_to_right = (0 if 1 else 0) if 0 else 1
> >>> right_to_left = 0 if 1 else (0 if 0 else 1)

I'd never want to rely on my own ability to remember the language
spec, so I strongly advocate for making it explicit with parens
regardless of what the language defines.  And that's if I ever created
such a mess in the first place.  If you have more than one pair of
conditional expressions in a single assignment, I'd suggest that it's
a code-smell that could use refactoring for clarity/disambiguity.

-tkc






From tjreedy at udel.edu  Thu Mar  6 15:15:34 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 06 Mar 2014 15:15:34 -0500
Subject: Ternary operator associativity
In-Reply-To: <20140306125958.31e096f8@bigbox.christie.dr>
References: <f3bd8da6-dc2e-4b05-b50b-3a2c9d825367@googlegroups.com>
 <20140306125958.31e096f8@bigbox.christie.dr>
Message-ID: <lfal16$6o5$1@ger.gmane.org>

On 3/6/2014 1:59 PM, Tim Chase wrote:
> On 2014-03-06 03:34, candide wrote:
>> According to the official documentation, the ternary operator has
>> left-to-right associativity
>>
>>>>> left_to_right = (0 if 1 else 0) if 0 else 1
>>>>> right_to_left = 0 if 1 else (0 if 0 else 1)
>
> I'd never want to rely on my own ability to remember the language
> spec, so I strongly advocate for making it explicit with parens
> regardless of what the language defines.  And that's if I ever created
> such a mess in the first place.  If you have more than one pair of
> conditional expressions in a single assignment, I'd suggest that it's
> a code-smell that could use refactoring for clarity/disambiguity.

It is intended and part of the PEP discussion that one be able to write 
chained conditional expression in Python

x = (a1 if c1 else
      a2 if c2 else
      a3 if c3 else
      a4)

without extra ()s, similar to what one can write in C (if I remember 
correctly)

x = c1 ? a1 :
     c2 ? a2 :
     c3 ? a3 :
          a4

both being abbreviations for chained if-elses

if   c1: x = a1
elif c2: x = a2
elif c3: x = a3
else:    x = a4

In all three cases, the conditions are evaluated in 1,2,3 order, each 
before the corresponding expression.

-- 
Terry Jan Reedy



From teddybubu at gmail.com  Thu Mar  6 15:22:30 2014
From: teddybubu at gmail.com (teddybubu at gmail.com)
Date: Thu, 6 Mar 2014 12:22:30 -0800 (PST)
Subject: beautiful soup get class info
Message-ID: <e73d29eb-17bb-472e-bdc4-c38ca904c60f@googlegroups.com>

I am using beautifulsoup to get the title and date of the website.
title is working fine but I am not able to pull the date. Here is the code in the url:

 <span class="date">October 22, 2011</span>

In Python, I am using the following code:
date1 = soup.span.text
data=soup.find_all(date="value") 

Results in:

[]
March 5, 2014

What is the proper way to get this info?
Thanks.


From gordon at panix.com  Thu Mar  6 15:58:12 2014
From: gordon at panix.com (John Gordon)
Date: Thu, 6 Mar 2014 20:58:12 +0000 (UTC)
Subject: beautiful soup get class info
References: <e73d29eb-17bb-472e-bdc4-c38ca904c60f@googlegroups.com>
Message-ID: <lfanh4$mna$1@reader1.panix.com>

In <e73d29eb-17bb-472e-bdc4-c38ca904c60f at googlegroups.com> teddybubu at gmail.com writes:

>  <span class="date">October 22, 2011</span>

> date1 = soup.span.text
> data=soup.find_all(date="value") 

Try this:

soup.find_all(name="span", class="date")

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon at panix.com    watch 'House', or a real serial killer to watch 'Dexter'.



From teddybubu at gmail.com  Thu Mar  6 16:38:39 2014
From: teddybubu at gmail.com (teddybubu at gmail.com)
Date: Thu, 6 Mar 2014 13:38:39 -0800 (PST)
Subject: beautiful soup get class info
In-Reply-To: <lfanh4$mna$1@reader1.panix.com>
References: <e73d29eb-17bb-472e-bdc4-c38ca904c60f@googlegroups.com>
 <lfanh4$mna$1@reader1.panix.com>
Message-ID: <ae5b837c-501d-498e-bd3a-3b2c709c42b0@googlegroups.com>

On Thursday, March 6, 2014 2:58:12 PM UTC-6, John Gordon wrote:
> In <e73d29eb-17bb-472e-bdc4-c38ca904c60f at googlegroups.com> teddy writes:
> 
> 
> 
> >  <span class="date">October 22, 2011</span>
> 
> 
> 
> > date1 = soup.span.text
> 
> > data=soup.find_all(date="value") 
> 
> 
> 
> Try this:
> 
> 
> 
> soup.find_all(name="span", class="date")
> 
> 
> 
> -- 
> 
> John Gordon         Imagine what it must be like for a real medical doctor to
> 
>     watch 'House', or a real serial killer to watch 'Dexter'.

I have python 2.7.2 and it does not like class in the code you provided. Now when I take out [ class="date"], this is returned:
   [<span class="date">March 5, 2014</span>, <span class="date">March 5, 2014</span>]
 
This is the code I am using: "data = soup.find_all(name="span") 
print (data)"
1. it returns today's date instead of the actual date
2. returns it twice


From larry.martell at gmail.com  Thu Mar  6 16:56:42 2014
From: larry.martell at gmail.com (Larry Martell)
Date: Thu, 6 Mar 2014 16:56:42 -0500
Subject: script uses up all memory
In-Reply-To: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
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On Wed, Mar 5, 2014 at 5:27 PM, Larry Martell <larry.martell at gmail.com> wrote:
> I have a script that forks off other processes and attempts to manage
> them. Here is a stripped down version of the script:
>
>         self.sleepTime = 300
>         self.procs = {}
>         self.startTimes = {}
>         self.cmd = ['python', '/usr/local/motor/motor/app/some_other_script.py']
>
>         while True:
>             try:
>                 self.tools = Tool.objects.filter(ip__isnull=False)
>             except Exception, e:
>                 print 'error from django call: ' + str(e)
>                 sys.exit(1)
>
>             for tool in self.tools:
>                 name = tool.name
>                 if name in self.procs:
>                     if self.procs[name].poll() is None:
>                         if
> (datetime.datetime.now()-self.startTimes[name]) >
> datetime.timedelta(hours=12):
>                             # it's been running too long - kill it
>                             print 'killing script for ' + name + "
> it's been running too long"
>                             self.procs[name].kill()
>                         else:
>                             continue
>
>                     if self.procs[name].returncode:
>                         print 'scrikpt failed for ' + name + ', error
> = ' + str(self.procs[name].returncode)
>
>                     print 'starting script.py for ' + name + ' at ' +
> str(datetime.datetime.now())
>                     try:
>                         self.procs[name] = subprocess.Popen(self.cmd)
>                         self.startTimes[name] = datetime.datetime.now()
>                     except Exception, e:
>                         print 'error from Popen: ' + str(e)
>                         sys.exit(1)
>                 else:
>                     print 'starting script.py for ' + name + ' at ' +
> str(datetime.datetime.now())
>                     try:
>                         self.procs[name] = subprocess.Popen(self.cmd)
>                         self.startTimes[name] = datetime.datetime.now()
>                     except Exception, e:
>                         print 'error from Popen: ' + str(e)
>                         sys.exit(1)
>
>                 time.sleep(self.sleepTime)
>
>
> The script does what it's intended to do, however after about 2 hours
> it has used up all the memory available and the machine hangs. Can
> anyone see something that I am doing here that would be using memory
> like this? Perhaps some immutable object needs to be repeatedly
> recreated?

I figured out what is causing this. Each pass through the loop it does:

self.tools = Tool.objects.filter(ip__isnull=False)

And that is what is causing the memory consumption. If I move that
outside the loop and just do that once the memory issue goes away. Now
I need to figure out why this is happening and how to prevent it as
they do want to query the db each pass through the loop in case it has
been updated.


From larry.martell at gmail.com  Thu Mar  6 17:07:01 2014
From: larry.martell at gmail.com (Larry Martell)
Date: Thu, 6 Mar 2014 17:07:01 -0500
Subject: script uses up all memory
In-Reply-To: <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
Message-ID: <CACwCsY67ZuVVk0G4chhvGwqmjV964o+C-0X-xp5mOpVmUX=4CA@mail.gmail.com>

On Thu, Mar 6, 2014 at 4:56 PM, Larry Martell <larry.martell at gmail.com> wrote:
> On Wed, Mar 5, 2014 at 5:27 PM, Larry Martell <larry.martell at gmail.com> wrote:
>> I have a script that forks off other processes and attempts to manage
>> them. Here is a stripped down version of the script:
>>
>>         self.sleepTime = 300
>>         self.procs = {}
>>         self.startTimes = {}
>>         self.cmd = ['python', '/usr/local/motor/motor/app/some_other_script.py']
>>
>>         while True:
>>             try:
>>                 self.tools = Tool.objects.filter(ip__isnull=False)
>>             except Exception, e:
>>                 print 'error from django call: ' + str(e)
>>                 sys.exit(1)
>>
>>             for tool in self.tools:
>>                 name = tool.name
>>                 if name in self.procs:
>>                     if self.procs[name].poll() is None:
>>                         if
>> (datetime.datetime.now()-self.startTimes[name]) >
>> datetime.timedelta(hours=12):
>>                             # it's been running too long - kill it
>>                             print 'killing script for ' + name + "
>> it's been running too long"
>>                             self.procs[name].kill()
>>                         else:
>>                             continue
>>
>>                     if self.procs[name].returncode:
>>                         print 'scrikpt failed for ' + name + ', error
>> = ' + str(self.procs[name].returncode)
>>
>>                     print 'starting script.py for ' + name + ' at ' +
>> str(datetime.datetime.now())
>>                     try:
>>                         self.procs[name] = subprocess.Popen(self.cmd)
>>                         self.startTimes[name] = datetime.datetime.now()
>>                     except Exception, e:
>>                         print 'error from Popen: ' + str(e)
>>                         sys.exit(1)
>>                 else:
>>                     print 'starting script.py for ' + name + ' at ' +
>> str(datetime.datetime.now())
>>                     try:
>>                         self.procs[name] = subprocess.Popen(self.cmd)
>>                         self.startTimes[name] = datetime.datetime.now()
>>                     except Exception, e:
>>                         print 'error from Popen: ' + str(e)
>>                         sys.exit(1)
>>
>>                 time.sleep(self.sleepTime)
>>
>>
>> The script does what it's intended to do, however after about 2 hours
>> it has used up all the memory available and the machine hangs. Can
>> anyone see something that I am doing here that would be using memory
>> like this? Perhaps some immutable object needs to be repeatedly
>> recreated?
>
> I figured out what is causing this. Each pass through the loop it does:
>
> self.tools = Tool.objects.filter(ip__isnull=False)
>
> And that is what is causing the memory consumption. If I move that
> outside the loop and just do that once the memory issue goes away. Now
> I need to figure out why this is happening and how to prevent it as
> they do want to query the db each pass through the loop in case it has
> been updated.

Apparently the object returned by that call is immutable as if I look
at id(self.tools) each pass through the loop, it is different. Is
there some way I can recover that memory?


From rosuav at gmail.com  Thu Mar  6 17:11:37 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 09:11:37 +1100
Subject: script uses up all memory
In-Reply-To: <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
Message-ID: <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>

On Fri, Mar 7, 2014 at 8:56 AM, Larry Martell <larry.martell at gmail.com> wrote:
> I figured out what is causing this. Each pass through the loop it does:
>
> self.tools = Tool.objects.filter(ip__isnull=False)
>
> And that is what is causing the memory consumption. If I move that
> outside the loop and just do that once the memory issue goes away. Now
> I need to figure out why this is happening and how to prevent it as
> they do want to query the db each pass through the loop in case it has
> been updated.

Interesting. So the next thing to do is to look into the
implementation of that. Does it allocate database resources and not
free them? Does it have internal reference loops?

Something to try: Put an explicit gc.collect() call into the loop. If
that solves your problem, you have a refloop somewhere (and you can
properly fix it by explicitly breaking the loop). If that keeps
returning large numbers, and especially if it populates gc.garbage
with a whole lot of stuff, then you definitely have refloops.

http://docs.python.org/2/library/gc.html

ChrisA


From rosuav at gmail.com  Thu Mar  6 17:12:54 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 09:12:54 +1100
Subject: script uses up all memory
In-Reply-To: <CACwCsY67ZuVVk0G4chhvGwqmjV964o+C-0X-xp5mOpVmUX=4CA@mail.gmail.com>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
 <CACwCsY67ZuVVk0G4chhvGwqmjV964o+C-0X-xp5mOpVmUX=4CA@mail.gmail.com>
Message-ID: <CAPTjJmqShyk9yH4G-7kGfo5GROhWDP57cyGC84eX5i3YN_ZpXQ@mail.gmail.com>

On Fri, Mar 7, 2014 at 9:07 AM, Larry Martell <larry.martell at gmail.com> wrote:
> Apparently the object returned by that call is immutable as if I look
> at id(self.tools) each pass through the loop, it is different. Is
> there some way I can recover that memory?

Not sure what mutability has to do with that. The changing id() simply
means you're getting back a new object every time. Normally, as soon
as your rebind self.tools to the new object, the old object will be
disposed of - unless it has refloops, which is what I mentioned in the
previous post, or has some other external reference.

ChrisA


From larry.martell at gmail.com  Thu Mar  6 17:21:26 2014
From: larry.martell at gmail.com (Larry Martell)
Date: Thu, 6 Mar 2014 17:21:26 -0500
Subject: script uses up all memory
In-Reply-To: <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
 <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>
Message-ID: <CACwCsY4LCg5Mw-fx_Og93ErJ_N14Vqw7TO2TrEnp3wAdY0POkg@mail.gmail.com>

On Thu, Mar 6, 2014 at 5:11 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Fri, Mar 7, 2014 at 8:56 AM, Larry Martell <larry.martell at gmail.com> wrote:
>> I figured out what is causing this. Each pass through the loop it does:
>>
>> self.tools = Tool.objects.filter(ip__isnull=False)
>>
>> And that is what is causing the memory consumption. If I move that
>> outside the loop and just do that once the memory issue goes away. Now
>> I need to figure out why this is happening and how to prevent it as
>> they do want to query the db each pass through the loop in case it has
>> been updated.
>
> Interesting. So the next thing to do is to look into the
> implementation of that. Does it allocate database resources and not
> free them? Does it have internal reference loops?
>
> Something to try: Put an explicit gc.collect() call into the loop. If
> that solves your problem, you have a refloop somewhere (and you can
> properly fix it by explicitly breaking the loop). If that keeps
> returning large numbers, and especially if it populates gc.garbage
> with a whole lot of stuff, then you definitely have refloops.
>
> http://docs.python.org/2/library/gc.html


First I added del(self.tools) before the Django call. That did not
stop the memory consumption. Then I added a call to gc.collect() after
the del and that did solve it. gc.collect() returns 0 each time, so
I'm going to declare victory and move on. No time to dig into the
Django code. Thanks.


From rosuav at gmail.com  Thu Mar  6 17:28:42 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 09:28:42 +1100
Subject: script uses up all memory
In-Reply-To: <CACwCsY4LCg5Mw-fx_Og93ErJ_N14Vqw7TO2TrEnp3wAdY0POkg@mail.gmail.com>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
 <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>
 <CACwCsY4LCg5Mw-fx_Og93ErJ_N14Vqw7TO2TrEnp3wAdY0POkg@mail.gmail.com>
Message-ID: <CAPTjJmqR+CXDG_jpmPa+u3cCzDbPpR8imAvy4Ys1+Q3zWU1CfQ@mail.gmail.com>

On Fri, Mar 7, 2014 at 9:21 AM, Larry Martell <larry.martell at gmail.com> wrote:
> First I added del(self.tools) before the Django call. That did not
> stop the memory consumption. Then I added a call to gc.collect() after
> the del and that did solve it. gc.collect() returns 0 each time, so
> I'm going to declare victory and move on. No time to dig into the
> Django code. Thanks.

Not all problems need to be solved perfectly :) But at very least, I
would put a comment against your collect() call explaining what
happens: that self.tools is involved in a refloop. Most Python code
shouldn't have to call gc.collect(), so it's worth explaining why you
are here.

ChrisA


From gordon at panix.com  Thu Mar  6 17:28:06 2014
From: gordon at panix.com (John Gordon)
Date: Thu, 6 Mar 2014 22:28:06 +0000 (UTC)
Subject: beautiful soup get class info
References: <e73d29eb-17bb-472e-bdc4-c38ca904c60f@googlegroups.com>
 <lfanh4$mna$1@reader1.panix.com>
 <ae5b837c-501d-498e-bd3a-3b2c709c42b0@googlegroups.com>
Message-ID: <lfaspm$998$1@reader1.panix.com>

In <ae5b837c-501d-498e-bd3a-3b2c709c42b0 at googlegroups.com> teddybubu at gmail.com writes:

> > soup.find_all(name="span", class="date")

> I have python 2.7.2 and it does not like class in the code you provided.

Oh right, 'class' is a reserved word.  I imagine beautifulsoup has
a workaround for that.

> Now when I take out [ class="date"], this is returned:
>    [<span class="date">March 5, 2014</span>, <span class="date">March 5, 2014</span>]
>  
> This is the code I am using: "data = soup.find_all(name="span") 
> print (data)"
> 1. it returns today's date instead of the actual date
> 2. returns it twice

Are there two occurrences of '<span class="date">March 5, 2014</span>'
in the HTML?  If so, then beautifulsoup is doing its job correctly.

It might help if you posted the sample HTML data you're working with.

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon at panix.com    watch 'House', or a real serial killer to watch 'Dexter'.



From marko at pacujo.net  Thu Mar  6 17:34:39 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 07 Mar 2014 00:34:39 +0200
Subject: script uses up all memory
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
 <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>
 <CACwCsY4LCg5Mw-fx_Og93ErJ_N14Vqw7TO2TrEnp3wAdY0POkg@mail.gmail.com>
 <mailman.7879.1394144925.18130.python-list@python.org>
Message-ID: <87ha7bq7ls.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Not all problems need to be solved perfectly :) But at very least, I
> would put a comment against your collect() call explaining what
> happens: that self.tools is involved in a refloop. Most Python code
> shouldn't have to call gc.collect(), so it's worth explaining why you
> are here.

Refloops also are nothing to be avoided. Let GC do its job and forget
about it.


Marko


From rosuav at gmail.com  Thu Mar  6 17:43:36 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 09:43:36 +1100
Subject: script uses up all memory
In-Reply-To: <87ha7bq7ls.fsf@elektro.pacujo.net>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
 <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>
 <CACwCsY4LCg5Mw-fx_Og93ErJ_N14Vqw7TO2TrEnp3wAdY0POkg@mail.gmail.com>
 <mailman.7879.1394144925.18130.python-list@python.org>
 <87ha7bq7ls.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmorKhaRzKDgk8_6DgAsyHfie9Wrnk+ORRKWttHv-GdRSQ@mail.gmail.com>

On Fri, Mar 7, 2014 at 9:34 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> Not all problems need to be solved perfectly :) But at very least, I
>> would put a comment against your collect() call explaining what
>> happens: that self.tools is involved in a refloop. Most Python code
>> shouldn't have to call gc.collect(), so it's worth explaining why you
>> are here.
>
> Refloops also are nothing to be avoided. Let GC do its job and forget
> about it.

I think this thread is proof that they are to be avoided. The GC
wasn't doing its job unless explicitly called on. The true solution is
to break the refloop; the quick fix is to call gc.collect(). I stand
by the recommendation to put an explanatory comment against the
collect call. [1]

ChrisA

[1] Here in Australia, that should be gc.reverse_charges().


From marko at pacujo.net  Thu Mar  6 18:12:31 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 07 Mar 2014 01:12:31 +0200
Subject: script uses up all memory
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
 <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>
 <CACwCsY4LCg5Mw-fx_Og93ErJ_N14Vqw7TO2TrEnp3wAdY0POkg@mail.gmail.com>
 <mailman.7879.1394144925.18130.python-list@python.org>
 <87ha7bq7ls.fsf@elektro.pacujo.net>
 <mailman.7880.1394145824.18130.python-list@python.org>
Message-ID: <87d2hyrkf4.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> I think this thread is proof that they are to be avoided. The GC
> wasn't doing its job unless explicitly called on. The true solution is
> to break the refloop; the quick fix is to call gc.collect(). I stand
> by the recommendation to put an explanatory comment against the
> collect call.

What I'm saying is that under most circumstances you shouldn't care if
the memory consumption goes up and down. The true solution is to not do
anything about temporary memory consumption. Also, you shouldn't worry
about breaking circular references. That is also often almost impossible
to accomplish as so much modern code builds on closures, which generate
all kinds of circular references under the hood?for your benefit, or
course.


Marko


From rosuav at gmail.com  Thu Mar  6 18:31:46 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 10:31:46 +1100
Subject: script uses up all memory
In-Reply-To: <87d2hyrkf4.fsf@elektro.pacujo.net>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
 <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>
 <CACwCsY4LCg5Mw-fx_Og93ErJ_N14Vqw7TO2TrEnp3wAdY0POkg@mail.gmail.com>
 <mailman.7879.1394144925.18130.python-list@python.org>
 <87ha7bq7ls.fsf@elektro.pacujo.net>
 <mailman.7880.1394145824.18130.python-list@python.org>
 <87d2hyrkf4.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmo8x7ur=M2zWDRnMK7N9zRq3MW+TCyX3zWAmc7Y2jc01w@mail.gmail.com>

On Fri, Mar 7, 2014 at 10:12 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> I think this thread is proof that they are to be avoided. The GC
>> wasn't doing its job unless explicitly called on. The true solution is
>> to break the refloop; the quick fix is to call gc.collect(). I stand
>> by the recommendation to put an explanatory comment against the
>> collect call.
>
> What I'm saying is that under most circumstances you shouldn't care if
> the memory consumption goes up and down. The true solution is to not do
> anything about temporary memory consumption. Also, you shouldn't worry
> about breaking circular references. That is also often almost impossible
> to accomplish as so much modern code builds on closures, which generate
> all kinds of circular references under the hood?for your benefit, or
> course.

This isn't a temporary issue, though - see the initial post. After two
hours of five-minutely checks, the computer was wedged. That's a
problem to be solved.

Most of what I do with closures can't create refloops, because the
function isn't referenced from inside itself. You'd need something
like this:

>>> def foo():
    x=1
    y=lambda: (x,y)
    return y
>>> len([foo() for _ in range(1000)])
1000
>>> gc.collect()
4000
>>> len([foo() for _ in range(1000)])
1000
>>> gc.collect()
4000
>>> len([foo() for _ in range(1000)])
1000
>>> gc.collect()
4000

That's repeatably creating garbage. But change the function to not
return itself, and there's no loop:

>>> def foo():
    x=1
    y=lambda: x
    return y
>>> gc.collect()
0
>>> len([foo() for _ in range(1000)])
1000
>>> gc.collect()
0
>>> len([foo() for _ in range(1000)])
1000
>>> gc.collect()
0

The only even reasonably common case that I can think of is a
recursive nested function:

>>> def foo(x):
    def y(f,x=x):
        f()
        for _ in range(x): y(f,x-1)
    return y

It's a function that returns a function that calls its argument some
number of times, where the number is derived in a stupid way from the
argument to the first function. The whole function is garbage, so it's
not surprising that the GC has to collect it.

>>> len([foo(5) for _ in range(1000)])
1000
>>> gc.collect()
3135
>>> len([foo(5) for _ in range(1000)])
1000
>>> gc.collect()
3135
>>> len([foo(5) for _ in range(1000)])
1000
>>> gc.collect()
3135

Can you give a useful example of a closure that does create a refloop?

ChrisA


From marko at pacujo.net  Thu Mar  6 18:53:03 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 07 Mar 2014 01:53:03 +0200
Subject: script uses up all memory
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
 <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>
 <CACwCsY4LCg5Mw-fx_Og93ErJ_N14Vqw7TO2TrEnp3wAdY0POkg@mail.gmail.com>
 <mailman.7879.1394144925.18130.python-list@python.org>
 <87ha7bq7ls.fsf@elektro.pacujo.net>
 <mailman.7880.1394145824.18130.python-list@python.org>
 <87d2hyrkf4.fsf@elektro.pacujo.net>
 <mailman.7881.1394148716.18130.python-list@python.org>
Message-ID: <878usmrijk.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Can you give a useful example of a closure that does create a refloop?

Just the other day, I mentioned the state pattern:

   class MyStateMachine:
       def __init__(self):
           sm = self

           class IDLE:
               def ding(self):
                   sm.open_door()
                   sm.state = AT_DOOR()

           class AT_DOOR:
               ...

           self.state = IDLE()

       def ding(self):
           self.state.ding()


So we have:

    MyStateMachine instance
      -> MyStateMachine instance.ding
         -> IDLE instance
            -> IDLE instance.ding
               -> MyStateMachine instance

plus numerous others in this example alone.

In general, event-driven programming produces circular references left
and right, and that might come into wider use with asyncio.

I suspect generators might create circular references as well.

Any tree data structure with parent references creates cycles.

In fact, I would imagine most OO designs create a pretty tight mesh of
back-and-forth references.


Marko


From contact at pycon-au.org  Thu Mar  6 19:07:03 2014
From: contact at pycon-au.org (PyCon AU)
Date: Fri, 7 Mar 2014 11:07:03 +1100
Subject: Call for Proposals: PyCon AU 2014 in Brisbane
Message-ID: <CAHrZfZDNX0oLx_KSm2gG1NmHm_-8BrMgJLUjV8mYc7aRnv2fiQ@mail.gmail.com>

PyCon Australia 2014 is pleased to announce that its Call for
Proposals is now open!

The conference this year will be held on Saturday 2 and Sunday 3 August
2014 in Brisbane. We'll also be featuring a day of miniconfs
on Friday 1 August.

The deadline for proposal submission is Friday April 25, 2014, and more
information can be found at http://pycon-au.org/cfp

PyCon Australia attracts professional developers from all walks of
life, including industry, government, and science, as well as
enthusiast and student developers. We're looking for proposals for
presentations and tutorials on any aspect of Python programming, at
all skill levels from novice to advanced.

Presentation subjects may range from reports on open source, academic
or commercial projects; or even tutorials and case studies. If a
presentation is interesting and useful to the Python community, it
will be considered for inclusion in the program.

We're especially interested in short presentations that will teach
conference-goers something new and useful. Can you show attendees how
to use a module? Explore a Python language feature? Package an
application?

Proposals about the Django web framework are very strongly encouraged,
and will also be considered for inclusion in DjangoCon AU, to be held
on Friday 1 August.

We welcome first-time speakers; we are a community conference and we
are eager to hear about your experience. If you have friends or
colleagues who have something valuable to contribute, twist their arms
to tell us about it! Please also forward this Call for Proposals to
anyone that you feel may be interested.

To find out more go to the official Call for Proposals page here:
http://pycon-au.org/cfp

See you in Brisbane in August!


== About PyCon Australia ==

PyCon Australia is the national conference for the Python Programming
Community. The fifth PyCon Australia will be held on August 1--5, 2014
in Brisbane, bringing together professional, student and enthusiast
developers with a love for developing with Python. PyCon Australia
informs the country's Python developers with presentations, tutorials
and panel sessions by experts and core developers of Python, as well
as the libraries and frameworks that they rely on.

To find out more about PyCon Australia 2014, visit our website at
http://pycon-au.org or e-mail us at contact at pycon-au.org.

PyCon Australia is presented by Linux Australia (www.linux.org.au) and
acknowledges the support of our Platinum Sponsor, Red Hat, and our Gold
sponsors, Google Australia and Netbox Blue. For full details of our
sponsors, see our website.
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From rosuav at gmail.com  Thu Mar  6 19:11:16 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 11:11:16 +1100
Subject: script uses up all memory
In-Reply-To: <878usmrijk.fsf@elektro.pacujo.net>
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
 <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>
 <CACwCsY4LCg5Mw-fx_Og93ErJ_N14Vqw7TO2TrEnp3wAdY0POkg@mail.gmail.com>
 <mailman.7879.1394144925.18130.python-list@python.org>
 <87ha7bq7ls.fsf@elektro.pacujo.net>
 <mailman.7880.1394145824.18130.python-list@python.org>
 <87d2hyrkf4.fsf@elektro.pacujo.net>
 <mailman.7881.1394148716.18130.python-list@python.org>
 <878usmrijk.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmqxGsJ8=DtV2nEvoNuCn-tZ2P7fmxc6WoRoj7B_0f8mQQ@mail.gmail.com>

On Fri, Mar 7, 2014 at 10:53 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> Can you give a useful example of a closure that does create a refloop?
>
> Just the other day, I mentioned the state pattern:
>
>    class MyStateMachine:
>        def __init__(self):
>            sm = self
>
>            class IDLE:
>                def ding(self):
>                    sm.open_door()
>                    sm.state = AT_DOOR()

Yeah, that's an extremely unusual way to do things. Why keep on
instantiating objects when you could just reference functions?

> In general, event-driven programming produces circular references left
> and right, and that might come into wider use with asyncio.

Nope; certainly not with closures. I do a whole lot of event-driven
programming (usually in Pike rather than Python, but they work the
same way in this), and there's no reference loop. Properly-done
event-driven programming should have two basic states: a reference
from some invisible thing that can trigger the event (eg a GUI widget)
to a callable, and a reference from that callable to its state. Once
the trigger is gone, the callable is dropped, its state is dropped,
and everything's cleaned up. You don't usually need a reference inside
the function to that function.

Don't forget, a closure need only hang onto the things it actually
uses. It doesn't need all its locals.

> I suspect generators might create circular references as well.

I doubt it.

>>> def foo(x):
    return ("x"*i for i in range(x))
>>> len([foo(5) for _ in range(1000)])
1000
>>> gc.collect()
0
>>> len([foo(5) for _ in range(1000)])
1000
>>> gc.collect()
0

Again, unless it keeps a reference to itself, there's no loop. It'll
need to hang onto some of its locals, but that's all.

> Any tree data structure with parent references creates cycles.

Yes, but how many of those do you actually have and drop? If you
create a GUI, you generally hold your entire widget tree stably. The
only issue is if you create a parent-child subtree and then drop it.
That shouldn't be being done in a tight loop. Most of the classic data
structures like trees are implemented at the C level, so again, your
code shouldn't be concerning itself with that.

> In fact, I would imagine most OO designs create a pretty tight mesh of
> back-and-forth references.

Examples, please? I can think of a handful of situations where I've
created reference loops, and they're sufficiently rare that I can put
comments against them and explicitly break them. For instance, I have
a "Subwindow" that has a "Connection". My window can have multiple
subwindows, a subwindow may or may not have a connection, and the
connection always references its subwindow. The subw->connection->subw
loop is explicitly broken when the connection is terminated. If the
window chooses to drop a subw, it first checks if there's a connection
(and prompts the user to confirm), and then will explicitly
disconnect, which breaks the refloop (as the connection's terminated).
I did a similar thing at work, again with explicit refloop breakage to
ensure clean removal. Apart from those two cases, I can't think of
anything in the last ten years where I've had a data structure with a
loop in it, where the whole loop could be dropped. (My MUD has a loop,
in that a character exists in a room, and the room keeps track of its
contents; but it's not logical to drop a room with characters in it,
and dropping a character is done by moving it to no-room, which breaks
the refloop.)

ChrisA


From marko at pacujo.net  Thu Mar  6 19:31:13 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 07 Mar 2014 02:31:13 +0200
Subject: script uses up all memory
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
 <CAPTjJmr=1CW3BP23x2RTmnfxWppUNz_m_jHp=6aBTF0qj3YkVw@mail.gmail.com>
 <CACwCsY4LCg5Mw-fx_Og93ErJ_N14Vqw7TO2TrEnp3wAdY0POkg@mail.gmail.com>
 <mailman.7879.1394144925.18130.python-list@python.org>
 <87ha7bq7ls.fsf@elektro.pacujo.net>
 <mailman.7880.1394145824.18130.python-list@python.org>
 <87d2hyrkf4.fsf@elektro.pacujo.net>
 <mailman.7881.1394148716.18130.python-list@python.org>
 <878usmrijk.fsf@elektro.pacujo.net>
 <mailman.7883.1394151084.18130.python-list@python.org>
Message-ID: <874n3argry.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Fri, Mar 7, 2014 at 10:53 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>    class MyStateMachine:
>>        def __init__(self):
>>            sm = self
>>
>>            class IDLE:
>>                def ding(self):
>>                    sm.open_door()
>>                    sm.state = AT_DOOR()
>
> Yeah, that's an extremely unusual way to do things. Why keep on
> instantiating objects when you could just reference functions?

That's not crucial. Even if the state objects were instantiated and
inner classes not used, you'd get the same circularity:

   class State:
       def __init__(self, sm):
           self.sm = sm

   class Idle(State):
       def ding(self):
           self.sm.open_door()
           self.sm.state = self.sm.AT_DOOR

   class AtDoor(state):
       ...

   class MyStateMachine:
       def __init__(self):
           self.IDLE = Idle(self)
           self.AT_DOOR = AtDoor(self)
           ...
           self.state = self.IDLE


The closure style is more concise and to the point and might perform no
worse.

> Nope; certainly not with closures. I do a whole lot of event-driven
> programming (usually in Pike rather than Python, but they work the
> same way in this), and there's no reference loop. Properly-done
> event-driven programming should have two basic states: a reference
> from some invisible thing that can trigger the event (eg a GUI widget)
> to a callable, and a reference from that callable to its state. Once
> the trigger is gone, the callable is dropped, its state is dropped,
> and everything's cleaned up. You don't usually need a reference inside
> the function to that function.

I'm more familiar with networking. If you need a timer, you need to be
able to start it so you need a reference to it. Ok, maybe you
instantiate a new timer each time, but you may need to cancel the timer
so starting the timer gives you a ticket you can use for canceling.
Similarly, you need a socket (wrapper) to signal an I/O state change,
and you also need to be able to close the socket at a bare minimum.

The task scheduling service (asyncio has one) collects thunks that refer
to your objects and your objects have a reference to the task scheduling
service to be able to schedule new tasks.

> Don't forget, a closure need only hang onto the things it actually
> uses. It doesn't need all its locals.

More importantly, there's nothing bad in circularity. No need to avoid
it. No need to cut cords.


Marko


From roy at panix.com  Thu Mar  6 20:24:21 2014
From: roy at panix.com (Roy Smith)
Date: Thu, 06 Mar 2014 20:24:21 -0500
Subject: Python programming
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <mailman.6815.1392256827.18130.python-list@python.org>
 <ldhcau$d9v$1@reader1.panix.com> <roy-A94C1B.22041912022014@news.panix.com>
 <5317e2ca$0$9232$e4fe514c@dreader35.news.xs4all.nl>
 <mailman.7884.1394151937.18130.python-list@python.org>
Message-ID: <roy-81D4FE.20242106032014@news.panix.com>

In article <mailman.7884.1394151937.18130.python-list at python.org>,
 Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:

> On 06 Mar 2014 02:51:54 GMT, albert at spenarnc.xs4all.nl (Albert van der
> Horst) declaimed the following:
> 
> >In article <roy-A94C1B.22041912022014 at news.panix.com>,
> >Roy Smith  <roy at panix.com> wrote:
> >>In article <ldhcau$d9v$1 at reader1.panix.com>,
> >> Grant Edwards <invalid at invalid.invalid> wrote:
> >>
> >>> On 2014-02-13, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> >>>
> >>> >    An S-100 wire-wrap board.
> >>>
> >>> Yup, been there done that!
> >>
> >>Never did S-100, but I did do a custom Unibus card (wirewrap).
> >>
> >>You know you're working with a Real Computer (tm) when the +5V power
> >>supply can deliver as much current as an arc welder.
> >
> >I've a 64 node Parsytec transputer system in the hall way with
> >dual 5V 100A power supplies. Does that count?
> 
> 	I spotted a device on the table of the company calibration office...
> 
> 	As I recall, it was a 100A capable resistor... 0.10 OHM.
> 
> 	No idea what it was meant for; big binding posts at one end, and a slab
> of sheet steel in a "W" shape (smooth curves, not sharp bends).

External shunt for an ammeter?


From teddybubu at gmail.com  Thu Mar  6 20:37:28 2014
From: teddybubu at gmail.com (teddybubu at gmail.com)
Date: Thu, 6 Mar 2014 17:37:28 -0800 (PST)
Subject: beautiful soup get class info
In-Reply-To: <lfaspm$998$1@reader1.panix.com>
References: <e73d29eb-17bb-472e-bdc4-c38ca904c60f@googlegroups.com>
 <lfanh4$mna$1@reader1.panix.com>
 <ae5b837c-501d-498e-bd3a-3b2c709c42b0@googlegroups.com>
 <lfaspm$998$1@reader1.panix.com>
Message-ID: <c303cbad-d790-43ce-a88d-2068ec8e371c@googlegroups.com>

On Thursday, March 6, 2014 4:28:06 PM UTC-6, John Gordon wrote:
> In <ae5b837c-501d-498e-bd3a-3b2c709c42b0 at googlegroups.com>  writes:
> 
> 
> 
> > > soup.find_all(name="span", class="date")
> 
> 
> 
> > I have python 2.7.2 and it does not like class in the code you provided.
> 
> 
> 
> Oh right, 'class' is a reserved word.  I imagine beautifulsoup has
> 
> a workaround for that.
> 
> 
> 
> > Now when I take out [ class="date"], this is returned:
> 
> >    [<span class="date">March 5, 2014</span>, <span class="date">March 5, 2014</span>]
> 
> >  
> 
> > This is the code I am using: "data = soup.find_all(name="span") 
> 
> > print (data)"
> 
> > 1. it returns today's date instead of the actual date
> 
> > 2. returns it twice
> 
> 
> 
> Are there two occurrences of '<span class="date">March 5, 2014</span>'
> 
> in the HTML?  If so, then beautifulsoup is doing its job correctly.
> 
> 
> 
> It might help if you posted the sample HTML data you're working with.
> 
> 
> 
> -- 
> 
> John Gordon         Imagine what it must be like for a real medical doctor to
> 
>    watch 'House', or a real serial killer to watch 'Dexter'.

ok I got this working. now to the next problem.... thanks.


From breamoreboy at yahoo.co.uk  Thu Mar  6 20:48:59 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Fri, 07 Mar 2014 01:48:59 +0000
Subject: beautiful soup get class info
In-Reply-To: <c303cbad-d790-43ce-a88d-2068ec8e371c@googlegroups.com>
References: <e73d29eb-17bb-472e-bdc4-c38ca904c60f@googlegroups.com>
 <lfanh4$mna$1@reader1.panix.com>
 <ae5b837c-501d-498e-bd3a-3b2c709c42b0@googlegroups.com>
 <lfaspm$998$1@reader1.panix.com>
 <c303cbad-d790-43ce-a88d-2068ec8e371c@googlegroups.com>
Message-ID: <lfb8i6$v6m$1@ger.gmane.org>

On 07/03/2014 01:37, teddybubu at gmail.com wrote:
> On Thursday, March 6, 2014 4:28:06 PM UTC-6, John Gordon wrote:
>> In <ae5b837c-501d-498e-bd3a-3b2c709c42b0 at googlegroups.com>  writes:
>>
>>
>>
>>>> soup.find_all(name="span", class="date")
>>
>>
>>
>>> I have python 2.7.2 and it does not like class in the code you provided.
>>
>>
>>
>> Oh right, 'class' is a reserved word.  I imagine beautifulsoup has
>>
>> a workaround for that.
>>
>>
>>
>>> Now when I take out [ class="date"], this is returned:
>>
>>>     [<span class="date">March 5, 2014</span>, <span class="date">March 5, 2014</span>]
>>
>>>
>>
>>> This is the code I am using: "data = soup.find_all(name="span")
>>
>>> print (data)"
>>
>>> 1. it returns today's date instead of the actual date
>>
>>> 2. returns it twice
>>
>>
>>
>> Are there two occurrences of '<span class="date">March 5, 2014</span>'
>>
>> in the HTML?  If so, then beautifulsoup is doing its job correctly.
>>
>>
>>
>> It might help if you posted the sample HTML data you're working with.
>>
>>
>>
>> --
>>
>> John Gordon         Imagine what it must be like for a real medical doctor to
>>
>>     watch 'House', or a real serial killer to watch 'Dexter'.
>
> ok I got this working. now to the next problem.... thanks.
>

I'm pleased to see that you have a solution.  Now, should you wish to 
ask further questions, would you please read and action this first 
https://wiki.python.org/moin/GoogleGroupsPython to prevent us seeing the 
double line spacing above, thanks.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From harrismh777 at gmail.com  Thu Mar  6 20:53:15 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Thu, 6 Mar 2014 17:53:15 -0800 (PST)
Subject: How security holes happen
In-Reply-To: <mailman.7885.1394152206.18130.python-list@python.org>
References: <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
 <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
 <d83922b0-2969-4fa1-aa3a-075f7ad4c44a@googlegroups.com>
 <CAPTjJmpCiNC7HHSQwmD4piTQt2VJY4mjQVSMvH=uCVqywm8ifQ@mail.gmail.com>
 <mailman.7850.1394065503.18130.python-list@python.org>
 <5adebc12-aa37-4139-82d8-563f46a27dc0@googlegroups.com>
 <mailman.7885.1394152206.18130.python-list@python.org>
Message-ID: <e34bed3d-920b-4faa-bdef-43cf241e8cab@googlegroups.com>

On Thursday, March 6, 2014 6:28:58 PM UTC-6, Dennis Lee Bieber wrote:
> 
> 	The 6502 was NOT a Motorola chip (they had the 6800).  The 6502 was MOS

That's funny... did you not see what I wrote back to MRAB?   Here:

The MOS 6502 is to the Motorola 6800 what the Zilog Z80 was to the Intel 8080.
   
    The same engineers who designed the 6800 moved out and then designed 
the 6502; actually ended up in a law suit of sorts--- but I don't remember the 
details. Anyway, the 6502 was bought outright by Commodore, and the rest 
is history with the VIC20. 



From harrismh777 at gmail.com  Thu Mar  6 20:54:16 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Thu, 6 Mar 2014 17:54:16 -0800 (PST)
Subject: test
Message-ID: <a98c7806-035a-4c39-b406-eecf2658192a@googlegroups.com>

disregard


From nispray at gmail.com  Thu Mar  6 21:03:11 2014
From: nispray at gmail.com (Wesley)
Date: Thu, 6 Mar 2014 18:03:11 -0800 (PST)
Subject: gdb unable to read python frame information
Message-ID: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>

Hi guys,
  My env: centos 6.5 64 bit; gdb 7.1; python 2.6.6

I wanna use gdb to attach my running python scripts.
Successfully import libpython in gdb, but seems all py operations failed to read python information.

Here is the snippet:
(gdb) python
>import libpython
>end
(gdb) py-bt
#3 (unable to read python frame information)
#5 (unable to read python frame information)
#7 (unable to read python frame information)
#9 (unable to read python frame information)
#18 (unable to read python frame information)
#22 (unable to read python frame information)
#26 (unable to read python frame information)
#28 (unable to read python frame information)
#29 (unable to read python frame information)
#38 (unable to read python frame information)
#39 (unable to read python frame information)
#40 (unable to read python frame information)
#42 (unable to read python frame information)
#44 (unable to read python frame information)
#45 (unable to read python frame information)
#47 (unable to read python frame information)
#49 (unable to read python frame information)
#51 (unable to read python frame information)
#55 (unable to read python frame information)
#62 (unable to read python frame information)
#64 (unable to read python frame information)
#76 (unable to read python frame information)
#88 (unable to read python frame information)
#100 (unable to read python frame information)
(gdb) py-locals
Unable to read information on python frame
(gdb) 

Is there anything wrong?
Thanks.
Wesley


From python at mrabarnett.plus.com  Thu Mar  6 21:13:02 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Fri, 07 Mar 2014 02:13:02 +0000
Subject: How security holes happen
In-Reply-To: <e34bed3d-920b-4faa-bdef-43cf241e8cab@googlegroups.com>
References: <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
 <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
 <d83922b0-2969-4fa1-aa3a-075f7ad4c44a@googlegroups.com>
 <CAPTjJmpCiNC7HHSQwmD4piTQt2VJY4mjQVSMvH=uCVqywm8ifQ@mail.gmail.com>
 <mailman.7850.1394065503.18130.python-list@python.org>
 <5adebc12-aa37-4139-82d8-563f46a27dc0@googlegroups.com>
 <mailman.7885.1394152206.18130.python-list@python.org>
 <e34bed3d-920b-4faa-bdef-43cf241e8cab@googlegroups.com>
Message-ID: <53192B2E.5010505@mrabarnett.plus.com>

On 2014-03-07 01:53, Mark H. Harris wrote:
> On Thursday, March 6, 2014 6:28:58 PM UTC-6, Dennis Lee Bieber wrote:
>>
>> 	The 6502 was NOT a Motorola chip (they had the 6800).  The 6502 was MOS
>
> That's funny... did you not see what I wrote back to MRAB?   Here:
>
> The MOS 6502 is to the Motorola 6800 what the Zilog Z80 was to the Intel 8080.
>
Not quite.

The Z80's architecture and instruction set is a superset of that of the
8080; the 6502's architecture and instruction set isn't a superset of,
or even compatible with, that of the 6800 (although it can use the same
I/O, etc, chips).

>      The same engineers who designed the 6800 moved out and then designed
> the 6502; actually ended up in a law suit of sorts--- but I don't remember the
> details. Anyway, the 6502 was bought outright by Commodore, and the rest
> is history with the VIC20.
>



From harrismh777 at gmail.com  Thu Mar  6 21:39:01 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Thu, 6 Mar 2014 18:39:01 -0800 (PST)
Subject: How security holes happen
In-Reply-To: <mailman.7887.1394158390.18130.python-list@python.org>
References: <mailman.7777.1393980007.18130.python-list@python.org>
 <roy-4E7DBB.20574304032014@news.panix.com>
 <mailman.7789.1393992721.18130.python-list@python.org>
 <871tyhp2vd.fsf@elektro.pacujo.net>
 <5316dfa4$0$2923$c3e8da3$76491128@news.astraweb.com>
 <d83922b0-2969-4fa1-aa3a-075f7ad4c44a@googlegroups.com>
 <CAPTjJmpCiNC7HHSQwmD4piTQt2VJY4mjQVSMvH=uCVqywm8ifQ@mail.gmail.com>
 <mailman.7850.1394065503.18130.python-list@python.org>
 <5adebc12-aa37-4139-82d8-563f46a27dc0@googlegroups.com>
 <mailman.7885.1394152206.18130.python-list@python.org>
 <e34bed3d-920b-4faa-bdef-43cf241e8cab@googlegroups.com>
 <mailman.7887.1394158390.18130.python-list@python.org>
Message-ID: <ffe47689-e594-446c-b2fc-71696114abe2@googlegroups.com>

On Thursday, March 6, 2014 8:13:02 PM UTC-6, MRAB wrote:
> 
> The Z80's architecture and instruction set is a superset of that of the
> 8080; the 6502's architecture and instruction set isn't a superset of,
> or even compatible with, that of the 6800 (although it can use the same
> I/O, etc, chips).

My point is not what, but who.  Motorola engineers designed the 6502. A rose
is a rose by any other name. Its the people who count... if Motorola had listened 
to those guys, who knows ... ?  neither here nor there now, or course.


From wrw at mac.com  Thu Mar  6 21:27:33 2014
From: wrw at mac.com (William Ray Wing)
Date: Thu, 06 Mar 2014 21:27:33 -0500
Subject: Python programming
In-Reply-To: <roy-81D4FE.20242106032014@news.panix.com>
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <mailman.6815.1392256827.18130.python-list@python.org>
 <ldhcau$d9v$1@reader1.panix.com> <roy-A94C1B.22041912022014@news.panix.com>
 <5317e2ca$0$9232$e4fe514c@dreader35.news.xs4all.nl>
 <mailman.7884.1394151937.18130.python-list@python.org>
 <roy-81D4FE.20242106032014@news.panix.com>
Message-ID: <7B71F73B-9D8D-4F01-A5D8-B788DA25E1B3@mac.com>


On Mar 6, 2014, at 8:24 PM, Roy Smith <roy at panix.com> wrote:

> In article <mailman.7884.1394151937.18130.python-list at python.org>,
> Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> 
>> On 06 Mar 2014 02:51:54 GMT, albert at spenarnc.xs4all.nl (Albert van der
>> Horst) declaimed the following:
>> 
>>> In article <roy-A94C1B.22041912022014 at news.panix.com>,
>>> Roy Smith  <roy at panix.com> wrote:
>>>> In article <ldhcau$d9v$1 at reader1.panix.com>,
>>>> Grant Edwards <invalid at invalid.invalid> wrote:
>>>> 
>>>>> On 2014-02-13, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>>>>> 
>>>>>>   An S-100 wire-wrap board.
>>>>> 
>>>>> Yup, been there done that!
>>>> 
>>>> Never did S-100, but I did do a custom Unibus card (wirewrap).
>>>> 
>>>> You know you're working with a Real Computer (tm) when the +5V power
>>>> supply can deliver as much current as an arc welder.
>>> 
>>> I've a 64 node Parsytec transputer system in the hall way with
>>> dual 5V 100A power supplies. Does that count?
>> 
>> 	I spotted a device on the table of the company calibration office...
>> 
>> 	As I recall, it was a 100A capable resistor... 0.10 OHM.
>> 
>> 	No idea what it was meant for; big binding posts at one end, and a slab
>> of sheet steel in a "W" shape (smooth curves, not sharp bends).
> 
> External shunt for an ammeter?
>  

More likely a dummy load for power supply testing.  (Normally, ammeter shunts are sized to dissipate as little power as possible.)

-Bill



From dieter at handshake.de  Fri Mar  7 02:10:20 2014
From: dieter at handshake.de (dieter)
Date: Fri, 07 Mar 2014 08:10:20 +0100
Subject: gdb unable to read python frame information
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
Message-ID: <87mwh2bi1v.fsf@handshake.de>

Wesley <nispray at gmail.com> writes:

> I wanna use gdb to attach my running python scripts.
> Successfully import libpython in gdb, but seems all py operations failed to read python information.
>
> Here is the snippet:
> (gdb) python
>>import libpython
>>end
> (gdb) py-bt
> #3 (unable to read python frame information)
> #5 (unable to read python frame information)

The simplest possible interpretation would be that your
Python lacks debugging symbols. That often happens with
system installed Python installations (which usually are stripped
to the bare minimal symbol set - as "normal" users do not need
debugging).

Try with a Python that you have generated yourself.



From rosuav at gmail.com  Fri Mar  7 02:16:55 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 18:16:55 +1100
Subject: Assertions are bad, m'kay?
Message-ID: <CAPTjJmrb6Ehbyfn7buQwRwiyGLBoZX0Xrq72_cw2CUg7QVF7jQ@mail.gmail.com>

They produce the wrong exception type, they disappear when you least
expect them, and now we have another reason not to use assert.

http://xkcd.com/1339/

Abusing assert for arg checking violates XKCD 1339. Write
standards-compliant code!

ChrisA


From cs at zip.com.au  Fri Mar  7 02:57:44 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Fri, 7 Mar 2014 18:57:44 +1100
Subject: why does "python --version" write to standard error?
Message-ID: <20140307075744.GA43732@cskk.homeip.net>

This seems to write the python version to standard error. That seems
very wrong. And at variance with the manual entry.

Commentry?
-- 
Cameron Simpson <cs at zip.com.au>

This is not a bug. It's just the way it works, and makes perfect sense.
        - Tom Christiansen <tchrist at jhereg.perl.com>
I like that line. I hope my boss falls for it.
        - Chaim Frenkel <chaimf at cris.com>


From orgnut at yahoo.com  Fri Mar  7 02:56:00 2014
From: orgnut at yahoo.com (Larry Hudson)
Date: Thu, 06 Mar 2014 23:56:00 -0800
Subject: Python programming
In-Reply-To: <mailman.7888.1394161816.18130.python-list@python.org>
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <mailman.6815.1392256827.18130.python-list@python.org>
 <ldhcau$d9v$1@reader1.panix.com> <roy-A94C1B.22041912022014@news.panix.com>
 <5317e2ca$0$9232$e4fe514c@dreader35.news.xs4all.nl>
 <mailman.7884.1394151937.18130.python-list@python.org>
 <roy-81D4FE.20242106032014@news.panix.com>
 <mailman.7888.1394161816.18130.python-list@python.org>
Message-ID: <pdOdnQ8qQLUH5oTOnZ2dnUVZ_tmdnZ2d@giganews.com>

<snip>

>>> 	I spotted a device on the table of the company calibration office...
>>>
>>> 	As I recall, it was a 100A capable resistor... 0.10 OHM.
>>>
>>> 	No idea what it was meant for; big binding posts at one end, and a slab
>>> of sheet steel in a "W" shape (smooth curves, not sharp bends).
>>
>> External shunt for an ammeter?
>>
>
> More likely a dummy load for power supply testing.  (Normally, ammeter shunts are sized to dissipate as little power as possible.)
>
> -Bill
>

Another (OT) story...

I used to work in an electronic calibration lab, but I don't recall having a resistor of that 
description -- however, it reminds me of another story...

While our job was calibrating and maintaining our company's electronics, we occasionally had to 
do some incoming inspection work -- checking incoming components for accuracy.  This particular 
time I had a batch of 0.1 ohm 1% resistors (I think those were the numbers, at least something 
on that order).  I found by checking them right at the body of the resistors they were 
out-of-spec low, and checking at the end of the leads they were out-of-spec high.  Fun!   :-)

To measure them, I used the lab's Current Calibrator -- a special power supply whose voltage was 
controlled to give a constant (dialed-in) current.  Then with a DVM and mini-hooks I could 
attach these DVM leads anyplace along the resistor's leads.  At 1 amp, the voltage (read on the 
DVM) was equal to the resistance.  Ohm's law, of course:  R = E/I, where I is a constant 1.  And 
1 amp was well within the power specs of these resistors.

I ended up checking them at a distance of about a quarter inch from the body, because I expected 
that would be about the way they would be eventually mounted.  They all passed that way.  And 
fortunately I never had another batch of these resistors!   :-)

      -=- Larry -=-



From nad at acm.org  Fri Mar  7 03:31:58 2014
From: nad at acm.org (Ned Deily)
Date: Fri, 07 Mar 2014 00:31:58 -0800
Subject: why does "python --version" write to standard error?
References: <20140307075744.GA43732@cskk.homeip.net>
Message-ID: <nad-552416.00315707032014@news.gmane.org>

In article <20140307075744.GA43732 at cskk.homeip.net>,
 Cameron Simpson <cs at zip.com.au> wrote:

> This seems to write the python version to standard error. That seems
> very wrong. And at variance with the manual entry.

Fixed in Python 3.4:
http://bugs.python.org/issue18338

-- 
 Ned Deily,
 nad at acm.org



From ra1717 at nyu.edu  Fri Mar  7 03:15:07 2014
From: ra1717 at nyu.edu (Romil Agrawal)
Date: Fri, 7 Mar 2014 03:15:07 -0500
Subject: problem running python 3.3 on mac os mavericks
Message-ID: <CAGVBtO7JeaKxfNai-pi1VnThrL2s4DE+V5HVuytVh9rdRD28mQ@mail.gmail.com>

I currently installed python 3.3.4 on mac os mavericks, and want to run it
on Wing IDE. Previously it was running python 2.7.6. When I tried to change
the python excitable in the wing ide configuration mode, and then restarted
it, a dialog box was displayed that said the interpreter of python 3.3.4 on
the specified path may not exist. Please help me sort this out. Also,
python 3.3.4 is installed on my mac and running on the IDLE, but the
terminal shows that the current version of python is 2.7.6. how can it be
possible. Please suggest something to sort this thing out.

Thanking you.
Regards,
Romil Agrawal
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From duncan.booth at invalid.invalid  Fri Mar  7 04:33:49 2014
From: duncan.booth at invalid.invalid (Duncan Booth)
Date: 7 Mar 2014 09:33:49 GMT
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
Message-ID: <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>

Chris Angelico <rosuav at gmail.com> wrote:

> On Sat, Mar 1, 2014 at 1:41 AM, Joshua Landau <joshua at landau.ws>
> wrote: 
>> Would it be better to add a check here, such that if this gets raised
>> to the top-level it includes a warning ("Addition was inplace;
>> variable probably mutated despite assignment failure")?
> 
> That'd require figuring out whether or not the variable was actually
> mutated, and that's pretty hard to work out. So there's a FAQ entry,
> which Zachary already posted:
> 
> http://docs.python.org/3/faq/programming.html#why-does-a-tuple-i-item-r
> aise-an-exception-when-the-addition-works 
> 
> Also, we just answer this question every now and then :) Presumably
> more often on -tutor than here.
> 
> ChrisA
Another take on this that I haven't seen discussed in this thread:

Is there any reason why tuples need to throw an exception on assigning to 
the element if the old value and new value are the same object?

If I say:

    a = ("spam", [10, 30], "eggs")

then

    a[0] = a[0]

won't actually mutate the object. So tuples could let that silently pass. 
Then you would be able to safely do:

    a[1] += [50]

but this would still throw an exception:

    a[0] += "x"

    

-- 
Duncan Booth http://kupuguy.blogspot.com


From cs at zip.com.au  Fri Mar  7 05:06:31 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Fri, 7 Mar 2014 21:06:31 +1100
Subject: why does "python --version" write to standard error?
In-Reply-To: <nad-552416.00315707032014@news.gmane.org>
References: <nad-552416.00315707032014@news.gmane.org>
Message-ID: <20140307100631.GA74648@cskk.homeip.net>

On 07Mar2014 00:31, Ned Deily <nad at acm.org> wrote:
> In article <20140307075744.GA43732 at cskk.homeip.net>,
>  Cameron Simpson <cs at zip.com.au> wrote:
> > This seems to write the python version to standard error. That seems
> > very wrong. And at variance with the manual entry.
> 
> Fixed in Python 3.4:
> http://bugs.python.org/issue18338

Excellent! My thanks to Berker Peksag and Michael Dickens and the
other ticket participants.
-- 
Cameron Simpson <cs at zip.com.au>

The double cam chain setup on the 1980's DOHC CB750 was another one of
Honda's pointless engineering breakthroughs. You know the cycle (if you'll
pardon the pun :-), Wonderful New Feature is introduced with much fanfare,
WNF is fawned over by the press, WNF is copied by the other three Japanese
makers (this step is sometimes optional), and finally, WNF is quietly dropped
by Honda.
        - Blaine Gardner, <blgardne at sim.es.com>


From nispray at gmail.com  Fri Mar  7 05:29:35 2014
From: nispray at gmail.com (Wesley)
Date: Fri, 7 Mar 2014 02:29:35 -0800 (PST)
Subject: gdb unable to read python frame information
In-Reply-To: <mailman.7889.1394176233.18130.python-list@python.org>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <mailman.7889.1394176233.18130.python-list@python.org>
Message-ID: <c583c21d-d0a2-449a-93e2-37db713b33ed@googlegroups.com>

Then, how to make python get debug symbols? 

Install python from source with some special configure options?


From ben+python at benfinney.id.au  Fri Mar  7 06:04:28 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Fri, 07 Mar 2014 22:04:28 +1100
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
Message-ID: <85fvmuw9qb.fsf@benfinney.id.au>

Duncan Booth <duncan.booth at invalid.invalid> writes:

> Is there any reason why tuples need to throw an exception on assigning
> to the element if the old value and new value are the same object?

Special cases aren't special enough to break the rules.

-- 
 \           ?I do not believe in forgiveness as it is preached by the |
  `\        church. We do not need the forgiveness of God, but of each |
_o__)                    other and of ourselves.? ?Robert G. Ingersoll |
Ben Finney



From rosuav at gmail.com  Fri Mar  7 06:11:13 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 22:11:13 +1100
Subject: Tuples and immutability
In-Reply-To: <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
Message-ID: <CAPTjJmqxdaxhz2VGjZs0886niOdAPLngL2eP_PeFvXZ39zBjSw@mail.gmail.com>

On Fri, Mar 7, 2014 at 8:33 PM, Duncan Booth
<duncan.booth at invalid.invalid> wrote:
> Is there any reason why tuples need to throw an exception on assigning to
> the element if the old value and new value are the same object?

It'd be easy enough to implement your own tuple subclass that behaves
that way. Try it! See how many situations it actually helps.

ChrisA


From steve+comp.lang.python at pearwood.info  Fri Mar  7 06:11:49 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 07 Mar 2014 11:11:49 GMT
Subject: Assertions are bad, m'kay?
References: <mailman.7890.1394176617.18130.python-list@python.org>
Message-ID: <5319a975$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Fri, 07 Mar 2014 18:16:55 +1100, Chris Angelico wrote:

> They produce the wrong exception type, they disappear when you least
> expect them, and now we have another reason not to use assert.
> 
> http://xkcd.com/1339/
> 
> Abusing assert for arg checking violates XKCD 1339. Write
> standards-compliant code!

Assertions are not bad! They're just misunderstood and abused.

(By the way, assertions are not the same as assumptions. Asserts can be 
used to check that assumptions are correct, or to check the internal 
logic of your reasoning. Whereas assumptions are just accepted as if they 
were correct, no questions asked.


You should read this guy's blog post on when to use assert:

http://import-that.dreamwidth.org/676.html

It's pretty damn good, if I do say so myself...

*whistles innocently*


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Fri Mar  7 06:24:29 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 22:24:29 +1100
Subject: Assertions are bad, m'kay?
In-Reply-To: <5319a975$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.7890.1394176617.18130.python-list@python.org>
 <5319a975$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmoZEtoQ=0BpsiJjyQiX_DOjN5rzQQDJHJrcBj6NfAYeCg@mail.gmail.com>

On Fri, Mar 7, 2014 at 10:11 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
>> http://xkcd.com/1339/
>>
>> Abusing assert for arg checking violates XKCD 1339. Write
>> standards-compliant code!
>
> Assertions are not bad! They're just misunderstood and abused.
>
> (By the way, assertions are not the same as assumptions. Asserts can be
> used to check that assumptions are correct, or to check the internal
> logic of your reasoning. Whereas assumptions are just accepted as if they
> were correct, no questions asked.

The XKCD does draw a distinction between assuming and asserting. And I
do say "for arg checking", which is the most common *abuse* of assert.
But mainly, I just like to share laughs :)

ChrisA


From __peter__ at web.de  Fri Mar  7 06:38:07 2014
From: __peter__ at web.de (Peter Otten)
Date: Fri, 07 Mar 2014 12:38:07 +0100
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <CAPTjJmqxdaxhz2VGjZs0886niOdAPLngL2eP_PeFvXZ39zBjSw@mail.gmail.com>
Message-ID: <lfcb2i$f4r$1@ger.gmane.org>

Chris Angelico wrote:

> On Fri, Mar 7, 2014 at 8:33 PM, Duncan Booth
> <duncan.booth at invalid.invalid> wrote:
>> Is there any reason why tuples need to throw an exception on assigning to
>> the element if the old value and new value are the same object?
> 
> It'd be easy enough to implement your own tuple subclass that behaves
> that way. Try it! See how many situations it actually helps.

>>> class T(tuple):
...     def __setitem__(self, index, value):
...             if value is not self[index]:
...                     raise TypeError("{} is not {}".format(value, 
self[index]))
... 
>>> for i, k in zip(range(250, 260), range(250, 260)):
...     T([i])[0] = k
... 
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "<stdin>", line 4, in __setitem__
TypeError: 257 is not 257

I'm not sure "help" is the right word here ;)



From rosuav at gmail.com  Fri Mar  7 06:45:54 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 7 Mar 2014 22:45:54 +1100
Subject: Tuples and immutability
In-Reply-To: <lfcb2i$f4r$1@ger.gmane.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <CAPTjJmqxdaxhz2VGjZs0886niOdAPLngL2eP_PeFvXZ39zBjSw@mail.gmail.com>
 <lfcb2i$f4r$1@ger.gmane.org>
Message-ID: <CAPTjJmon6kQmx+kV-5zHD8DOAD=JEyCo39Ztp+tRFU04og+4rQ@mail.gmail.com>

On Fri, Mar 7, 2014 at 10:38 PM, Peter Otten <__peter__ at web.de> wrote:
> TypeError: 257 is not 257
>
> I'm not sure "help" is the right word here ;)

It doesn't help with non-small integers, yes, but the original case
was a list. Personally, I don't think there are many situations that
would benefit from it, plus it'd be confusing ("I can use += with a
list but not a number, why not?!").

ChrisA


From alister.ware at ntlworld.com  Fri Mar  7 06:51:28 2014
From: alister.ware at ntlworld.com (Alister)
Date: Fri, 07 Mar 2014 11:51:28 GMT
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
Message-ID: <4piSu.17150$NC.10985@fx27.am4>

On Fri, 07 Mar 2014 09:33:49 +0000, Duncan Booth wrote:

> Chris Angelico <rosuav at gmail.com> wrote:
> 
>> On Sat, Mar 1, 2014 at 1:41 AM, Joshua Landau <joshua at landau.ws> wrote:
>>> Would it be better to add a check here, such that if this gets raised
>>> to the top-level it includes a warning ("Addition was inplace;
>>> variable probably mutated despite assignment failure")?
>> 
>> That'd require figuring out whether or not the variable was actually
>> mutated, and that's pretty hard to work out. So there's a FAQ entry,
>> which Zachary already posted:
>> 
>> http://docs.python.org/3/faq/programming.html#why-does-a-tuple-i-item-r
>> aise-an-exception-when-the-addition-works
>> 
>> Also, we just answer this question every now and then :) Presumably
>> more often on -tutor than here.
>> 
>> ChrisA
> Another take on this that I haven't seen discussed in this thread:
> 
> Is there any reason why tuples need to throw an exception on assigning
> to the element if the old value and new value are the same object?
> 
> If I say:
> 
>     a = ("spam", [10, 30], "eggs")
> 
> then
> 
>     a[0] = a[0]
> 
> won't actually mutate the object. So tuples could let that silently
> pass.
> Then you would be able to safely do:
> 
>     a[1] += [50]
> 
> but this would still throw an exception:
> 
>     a[0] += "x"

I would think it would be better if the exception was thrown before the 
assignment to the list took place
simply seeing that a modification action was being applied to a tupple 
should be enough.
this would alert the programmer to the fact that he was trying something 
that may have undesired consequences
 



-- 
Old age is the harbor of all ills.
		-- Bion


From thrinaxodon.of.use.net123 at gmail.com  Fri Mar  7 07:27:30 2014
From: thrinaxodon.of.use.net123 at gmail.com (thrinaxodon.of.use.net123 at gmail.com)
Date: Fri, 7 Mar 2014 04:27:30 -0800 (PST)
Subject: GOLLY! HUMANS HAVE ORIGINS IN THE DEVONIAN!
Message-ID: <2ed20849-bec6-4d97-95ae-5621fe689015@googlegroups.com>

======================
>HOLY F*CKING GOD DAMNED NEWS!
======================
>
WELCOME TO YOUR NUMBER ONE SOURCE FOR PRESTIGIOUS BULLLSHIT! THE KIND YOU CAN ONLY GET FROM THRINAXODON CRAZY CHEESY!
>
NOW FOR YOUR FAVORITE TIME SLOT:
>
==========================
>
THRINAXODON FOUND 3  HUMAN FOSSILS FROM DEVONIAN STRATA IN GREENLAND.
>
ONE OF THEM WAS A NICE KNEECAP.
>
THE MOST BEAUTIFUL KNEECAP EVER DISCOVERED.
>
I CALLED OUT CARTER N.
>
CARTER CAME RUSHING OVER. WE TOOK THE KNEECAP FROM THE INUIT SAVAGES AND FLEW TO THE SMITHSONIAN.
>
THEY CALLED US KOOKS AND SLAMMED THE DOOR.
>
======================================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN: 

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/6f501c469c7af24f#
 
https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/3aad75c16afb0b82#
 


From ndbecker2 at gmail.com  Fri Mar  7 08:23:20 2014
From: ndbecker2 at gmail.com (Neal Becker)
Date: Fri, 07 Mar 2014 08:23:20 -0500
Subject: gdb unable to read python frame information
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <87mwh2bi1v.fsf@handshake.de>
Message-ID: <lfch7q$hff$1@ger.gmane.org>

dieter wrote:

> Wesley <nispray at gmail.com> writes:
> 
>> I wanna use gdb to attach my running python scripts.
>> Successfully import libpython in gdb, but seems all py operations failed to
>> read python information.
>>
>> Here is the snippet:
>> (gdb) python
>>>import libpython
>>>end
>> (gdb) py-bt
>> #3 (unable to read python frame information)
>> #5 (unable to read python frame information)
> 
> The simplest possible interpretation would be that your
> Python lacks debugging symbols. That often happens with
> system installed Python installations (which usually are stripped
> to the bare minimal symbol set - as "normal" users do not need
> debugging).
> 
> Try with a Python that you have generated yourself.

You probably need to install the python-debuginfo package



From robin at reportlab.com  Fri Mar  7 08:33:59 2014
From: robin at reportlab.com (Robin Becker)
Date: Fri, 07 Mar 2014 13:33:59 +0000
Subject: debugging on windows
Message-ID: <5319CAC7.4010200@chamonix.reportlab.co.uk>

Using

> Python 3.3.3 (v3.3.3:c3896275c0f6, Nov 18 2013, 21:18:40) [MSC v.1600 32 bit (Intel)] on win32
> Type "help", "copyright", "credits" or "license" for more information.

to run a tkinter + pmw2 application I have the following error on windows xp sp3

> Unhandled exception at 0x1e0aebb8 in python.exe: 0xC0000005: Access violation reading location 0x00000048.

the main window has appeared and the app is in a module search to find 
files/classes that might be relevant. VS 2010 indicates the error is some where 
  in the python33 dll. The code appears to run fine in 2.7, but should be 
compatible with 3.3.x

Is my only hope to add more print statements or use pdb or should I try and 
compile python 3.3.x myself and get the search narrowed with VS? The issue is 
complicated by my having redirected all outputs to some message windows using 
fake files for stderr & stdout.


-- 
Robin Becker



From roy at panix.com  Fri Mar  7 08:37:52 2014
From: roy at panix.com (Roy Smith)
Date: Fri, 07 Mar 2014 08:37:52 -0500
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
Message-ID: <roy-4B4028.08375207032014@news.panix.com>

In article <XnsA2E95FA1E1EB6duncanbooth at 127.0.0.1>,
 Duncan Booth <duncan.booth at invalid.invalid> wrote:

> Is there any reason why tuples need to throw an exception on assigning to 
> the element if the old value and new value are the same object?
> 
> If I say:
> 
>     a = ("spam", [10, 30], "eggs")
> 
> then
> 
>     a[0] = a[0]
> 
> won't actually mutate the object. So tuples could let that silently pass. 

But, why would you want them to?  What a way to introduce bugs which are 
difficult to test for.


From invalid at invalid.invalid  Fri Mar  7 12:00:49 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Fri, 7 Mar 2014 17:00:49 +0000 (UTC)
Subject: Python programming
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <mailman.6815.1392256827.18130.python-list@python.org>
 <ldhcau$d9v$1@reader1.panix.com> <roy-A94C1B.22041912022014@news.panix.com>
 <5317e2ca$0$9232$e4fe514c@dreader35.news.xs4all.nl>
 <mailman.7884.1394151937.18130.python-list@python.org>
 <roy-81D4FE.20242106032014@news.panix.com>
 <mailman.7888.1394161816.18130.python-list@python.org>
Message-ID: <lfcu01$872$1@reader1.panix.com>

On 2014-03-07, William Ray Wing <wrw at mac.com> wrote:
> On Mar 6, 2014, at 8:24 PM, Roy Smith <roy at panix.com> wrote:

>>> I spotted a device on the table of the company calibration office...
>>> 
>>> As I recall, it was a 100A capable resistor... 0.10 OHM.
>>> 
>>> No idea what it was meant for; big binding posts at one end, and a
>>> slab of sheet steel in a "W" shape (smooth curves, not sharp bends).
>> 
>> External shunt for an ammeter?
>>  
>
> More likely a dummy load for power supply testing.

Could be.  Back when I was working on PWM controllers for golf cart
and small car motors, we used to use steel coathangers for test loads,
but once they got past orange and more towards yellow, they started to
get too soft.  An appropriately dimensioned chunk of sheet steel would
have been ideal.

> (Normally, ammeter shunts are sized to dissipate as little power as
> possible.)

I've used chunks of coathanger for that too, but I don't think the
resistance was stable enough over temperature to trust the results at
higher currents.

-- 
Grant Edwards               grant.b.edwards        Yow! If elected, Zippy
                                  at               pledges to each and every
                              gmail.com            American a 55-year-old
                                                   houseboy ...


From john_ladasky at sbcglobal.net  Fri Mar  7 13:03:35 2014
From: john_ladasky at sbcglobal.net (John Ladasky)
Date: Fri, 7 Mar 2014 10:03:35 -0800 (PST)
Subject: Python programming
In-Reply-To: <mailman.6827.1392280246.18130.python-list@python.org>
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <roy-18C608.22022011022014@news.panix.com>
 <201402112314.42370.gheskett@wdtv.com> <ldftlc$ohg$1@ger.gmane.org>
 <mailman.6815.1392256827.18130.python-list@python.org>
 <ldhcau$d9v$1@reader1.panix.com> <roy-A94C1B.22041912022014@news.panix.com>
 <82055DB9-758F-4B4C-9993-FE4DA60E3D50@mac.com>
 <mailman.6827.1392280246.18130.python-list@python.org>
Message-ID: <560e7dcc-6557-44b8-89f7-adaafa9f0e29@googlegroups.com>

On Thursday, February 13, 2014 12:30:39 AM UTC-8, Larry.... at gmail.com wrote:
> On Wed, Feb 12, 2014 at 10:56 PM, William Ray Wing <w... at mac.com> wrote:
> 
> > OK, and how many of you remember the original version of the tongue-in-cheek essay "Real Programmers Don't Use Pascal" from the back page of Datamation?
> 
> I do remember it.
> 
> http://www.webcitation.org/659yh1oSh


As do I, though I couldn't have been more than about 16 years old when it came out.  I just re-read it, and this comment jumped out at me:

"Neither OS/370 nor FORTRAN show any signs of dying out, despite all the efforts of Pascal programmers the world over."

Well, OS/370, RIP.

As for FORTRAN?  This week, I actually downloaded an application which required a FORTRAN compiler.  This is the only FORTRAN application I've ever needed.  It's not old code, the first revision came out about 10 years ago.  More than once, I have queried Google with the phrase "Why isn't FORTRAN dead yet?"  For some reason, it lives on.  I can't say that I understand why.  


From gheskett at wdtv.com  Fri Mar  7 12:49:07 2014
From: gheskett at wdtv.com (Gene Heskett)
Date: Fri, 7 Mar 2014 12:49:07 -0500
Subject: Python programming
In-Reply-To: <lfcu01$872$1@reader1.panix.com>
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <mailman.7888.1394161816.18130.python-list@python.org>
 <lfcu01$872$1@reader1.panix.com>
Message-ID: <201403071249.07333.gheskett@wdtv.com>

On Friday 07 March 2014 12:29:38 Grant Edwards did opine:

> On 2014-03-07, William Ray Wing <wrw at mac.com> wrote:
> > On Mar 6, 2014, at 8:24 PM, Roy Smith <roy at panix.com> wrote:
> >>> I spotted a device on the table of the company calibration office...
> >>> 
> >>> As I recall, it was a 100A capable resistor... 0.10 OHM.
> >>> 
> >>> No idea what it was meant for; big binding posts at one end, and a
> >>> slab of sheet steel in a "W" shape (smooth curves, not sharp bends).
> >> 
> >> External shunt for an ammeter?
> > 
> > More likely a dummy load for power supply testing.
> 
> Could be.  Back when I was working on PWM controllers for golf cart
> and small car motors, we used to use steel coathangers for test loads,
> but once they got past orange and more towards yellow, they started to
> get too soft.  An appropriately dimensioned chunk of sheet steel would
> have been ideal.
> 
> > (Normally, ammeter shunts are sized to dissipate as little power as
> > possible.)
> 
> I've used chunks of coathanger for that too, but I don't think the
> resistance was stable enough over temperature to trust the results at
> higher currents.

This is really really offtopic but since its turned into war stories,
I recall one time that I needed to test a 5v 200amp supply that there were 
2 of in an old NEC Digital Video Effects unit,  I looked up the R per 1000' 
of standard romex in the various gauges & went over the Lowes and bought a 
100' roll of of 10/2.  Soldered the inside end together after striping and 
twisting it together,  It worked well, but the PSU didn't.  Made by HP back 
when they _thought_ they knew about how to build cement block sized power 
supplies. The psu went into foldback at about 20 amps.  All the bugs were 
good, nothing running warm.  Analyzing backwards in view of the curie point 
on some ferrite's being below the boiling point of water, I finally came to 
the conclusion that the ferrite in the output transformer had gone 
austenitic, eg totally non-magnetic, like it was just so much air, which is 
what many of those compounds will do if magnetized near saturation when 
they hit the curie point, and will never recover from.  HP of course didn't 
have the transformer or a replacement supply, but I found some Pioneer's 
with a suitable rating at M.P.Jones in FL and broke their hands putting a 
check for 2 of them in them, shipped yesterday.  That was in about 1997 & 
they were still in service when we turned analog tv off June 30, 2008. 

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

NOTICE: Will pay 100 USD for an HP-4815A defective but
complete probe assembly.



From nexusrawesome at gmail.com  Fri Mar  7 12:55:52 2014
From: nexusrawesome at gmail.com (NexusRAwesome1995 .)
Date: Fri, 7 Mar 2014 17:55:52 +0000
Subject: Is their a command to view code?
Message-ID: <CAEcfQzO7hS+Eq4Cw0FT5itoc3HQHEmpoywiinF0xrBLJ2GeuaQ@mail.gmail.com>

I am making a text based aventure game for my assignment and a friends test
run has somehow saved over the entire code file and now im using an earlier
version of the code. I have 0 idea if there is anyway to look at the code
using the IDLE and i need to do it to see how i fixed the fatal error left
behind by a friend. My on computer backup has not worked and the backup on
my memory stick also has the same problem.
If anyone knows of a way to get my code back i will be grateful as this is
my 1st project and i'm not that used to the syntax.
the item added is the outcome of what happened.
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Python 2.7.3 (default, Apr 10 2012, 23:31:26) [MSC v.1500 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
================================ RESTART ================================
>>> 
REMEMBER TO TYPE ALL YOUR ANSWERS IN LOWERCASE (EXCEPT YOUR OWN NAME)
>>> 
>>> ================================ RESTART ================================
>>> 
REMEMBER TO TYPE ALL YOUR ANSWERS IN LOWERCASE (EXCEPT YOUR OWN NAME)
BECAUSE THIS IS OUR FIRST GAME, ANY ANSWERS NOT ENTERED PERFECTLY WILL RESULT IN THE GAME ENDING, SO BE CAREFUL!
Hello, please enter your name:
Marcus Hyde
Marcus Hyde, You begin your adventure in the forest, with Princess Violet.
You proceed to climb a tree to pick an apple when you hear her scream.
A group of Orcs have taken the princess!
What will you do?
 Attack
 Run
attack
You try to attack one of the Orcs but they are too strong!
You are knocked out!
...
You awaken moments later to see a spirit in front of you.
The spirit presents you with three choices, select one.
 Sword
 Staff
 Bow
staff
You chose Staff!
('Staff does ', 4, ' damage!')
You are now equiped with a weapon!
Weapons increase your attack power, making you capable of defeating stronger opponents!
When you are given a choice, you can check your stats by typing 'stats'
Give it a try!
What will you do?
 Stats
stats
('HP = ', 10)
('Attack = ', 4)
('Defense = ', 0)
As you advance through the game, you may find items to increase your stats.
...
Before you can move, you are attacked by a Rogue!
Rogue HP = 3
What will you do?
 Attack
 Run
attack
('You attack the Rogue and deal ', 4, ' damage.')
You defeated the Rogue!
Rogue droped an item!
What will you do?
 Check
 Leave
check
You found a Wooden Shield!
Defense = 1
What will you do?
 Stats
 Continue
continue
You continue in search of the Princess and find a cave.
There is a lit torch at the entrance of the cave.
You take the torch and proceed to enter the cave.
As you walk through the cave you notice strange symbols on the walls, what could they mean?
You continue walking and come across two paths.
You hear the sound of several Orcs coming from the Left path.
You feel the wind coming from the Right path, this way is the fastest to the exit.
What will you do?
 Left
 Right
left
Despite hearing several Orcs, you choose to take the left path.
You fall into a pit with 5 Orcs, one of them attacks you!
Orc HP = 6
What will you do?
 Attack
 Run
run
You try to run away but the Orcs grab you.
The Orcs beat you to death.
GAME OVER
>>> fuck

Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    fuck
NameError: name 'fuck' is not defined
>>> 

From ian.g.kelly at gmail.com  Fri Mar  7 13:23:10 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 7 Mar 2014 11:23:10 -0700
Subject: Tuples and immutability
In-Reply-To: <4piSu.17150$NC.10985@fx27.am4>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <4piSu.17150$NC.10985@fx27.am4>
Message-ID: <CALwzid=9D7DujiwM=52CQ8dANnrgbTsUq7ZZ29mmFmCaVHswXw@mail.gmail.com>

On Fri, Mar 7, 2014 at 4:51 AM, Alister <alister.ware at ntlworld.com> wrote:
> I would think it would be better if the exception was thrown before the
> assignment to the list took place
> simply seeing that a modification action was being applied to a tupple
> should be enough.
> this would alert the programmer to the fact that he was trying something
> that may have undesired consequences

Then the behavior of tuples would be inconsistent with other immutable
types.  This can't be applied generally, because the Python
interpreter doesn't generally know whether a given type is supposed to
be immutable or not.


From ian.g.kelly at gmail.com  Fri Mar  7 13:37:10 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 7 Mar 2014 11:37:10 -0700
Subject: Is their a command to view code?
In-Reply-To: <CAEcfQzO7hS+Eq4Cw0FT5itoc3HQHEmpoywiinF0xrBLJ2GeuaQ@mail.gmail.com>
References: <CAEcfQzO7hS+Eq4Cw0FT5itoc3HQHEmpoywiinF0xrBLJ2GeuaQ@mail.gmail.com>
Message-ID: <CALwzidmSufXAT1yh3CkW29CarWNo4OFasWauCuDenwqYr-1v1w@mail.gmail.com>

On Fri, Mar 7, 2014 at 10:55 AM, NexusRAwesome1995 .
<nexusrawesome at gmail.com> wrote:
> I am making a text based aventure game for my assignment and a friends test
> run has somehow saved over the entire code file and now im using an earlier
> version of the code. I have 0 idea if there is anyway to look at the code
> using the IDLE and i need to do it to see how i fixed the fatal error left
> behind by a friend. My on computer backup has not worked and the backup on
> my memory stick also has the same problem.
> If anyone knows of a way to get my code back i will be grateful as this is
> my 1st project and i'm not that used to the syntax.
> the item added is the outcome of what happened.

Sorry, Python doesn't keep the source code in memory.  If the game is
still running in the interpreter, you can ask it for the source code
of a particular code object, but it implements this by opening the
source file and reading it in.  Since you've overwritten the file, the
source code would be wrong.  The best that you could do in this case
would be to disassemble the code objects using the dis.dis() function,
and then try to reverse-engineer the Python code from the byte code.
If the interpreter is no longer running, then there is nothing you can
do.

For the future, I strongly recommend using a version control system,
such as the free and relatively lightweight Mercurial.  Then when you
have these kinds of mishaps all you have to do is check the most
recent version of the code out of the repository again.  You should of
course continue to create backups as well, in case of more disastrous
events (although memory sticks are far too failure-prone to be
considered a reliable backup solution IMO).


From joel.goldstick at gmail.com  Fri Mar  7 13:46:03 2014
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Fri, 7 Mar 2014 13:46:03 -0500
Subject: Is their a command to view code?
In-Reply-To: <CAEcfQzO7hS+Eq4Cw0FT5itoc3HQHEmpoywiinF0xrBLJ2GeuaQ@mail.gmail.com>
References: <CAEcfQzO7hS+Eq4Cw0FT5itoc3HQHEmpoywiinF0xrBLJ2GeuaQ@mail.gmail.com>
Message-ID: <CAPM-O+x7Pfcj3dvPsobLSAwwjXB2yTJ81SbZ=_8A-5ef0OtWNA@mail.gmail.com>

On Mar 7, 2014 1:16 PM, "NexusRAwesome1995 ." <nexusrawesome at gmail.com>
wrote:
>
> I am making a text based aventure game for my assignment and a friends
test run has somehow saved over the entire code file and now im using an
earlier version of the code. I have 0 idea if there is anyway to look at
the code using the IDLE and i need to do it to see how i fixed the fatal
error left behind by a friend. My on computer backup has not worked and the
backup on my memory stick also has the same problem.
> If anyone knows of a way to get my code back i will be grateful as this
is my 1st project and i'm not that used to the syntax.
> the item added is the outcome of what happened.
>
You will be better off asking on python tutor list. However, go back to the
source you have and debug it
> --
> https://mail.python.org/mailman/listinfo/python-list
>
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From teddybubu at gmail.com  Fri Mar  7 15:27:27 2014
From: teddybubu at gmail.com (teddybubu at gmail.com)
Date: Fri, 7 Mar 2014 12:27:27 -0800 (PST)
Subject: extract from json
Message-ID: <d72d9e78-ee11-4833-b3b2-e90ab52a6d4c@googlegroups.com>

I can't find any example on how to do this.
I have a json file like so:
{"bostock":[{"url":"http://bl.ocks.org/mbostock/9360565","title":"titleplaceholder","date":"dateplaceholder"},
{"url":"http://bl.ocks.org/mbostock/9265674","title":"titleplaceholder","date":"dateplaceholder"},
{"url":"http://bl.ocks.org/mbostock/9265467","title":"titleplaceholder","date":"dateplaceholder"},
{"url":"http://bl.ocks.org/mbostock/9234731","title":"titleplaceholder","date":"dateplaceholder"},
{"url":"http://bl.ocks.org/mbostock/9232962","title":"titleplaceholder","date":"dateplaceholder"},

this goes on for more than 700 entries. only thing unique is the number at the end of the url. I am going to load the url in python, get the date and title and write it in the json itself. 
Right now I am stuck on just reading the url in the json. Here is my code:

import json

with open("bostock.json") as json_file:
    json_data = json.load(json_file)
    print(json_data)

I have tried json_data[0], json_data.url and a few others I forget right now and it does not seem to work.  

I have already figured out how to get the title and date.
First things first: How can i just get the url for each line of the above json file? 


From nad at acm.org  Fri Mar  7 15:47:15 2014
From: nad at acm.org (Ned Deily)
Date: Fri, 07 Mar 2014 12:47:15 -0800
Subject: gdb unable to read python frame information
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <mailman.7889.1394176233.18130.python-list@python.org>
 <c583c21d-d0a2-449a-93e2-37db713b33ed@googlegroups.com>
Message-ID: <nad-105FEC.12471507032014@news.gmane.org>

In article <c583c21d-d0a2-449a-93e2-37db713b33ed at googlegroups.com>,
 Wesley <nispray at gmail.com> wrote:
> Then, how to make python get debug symbols? 
> 
> Install python from source with some special configure options?

If your distribution doesn't have a debug version of Python and you need 
to build your own, add --with-pydebug to your ./configure options.  See:

./configure --help

-- 
 Ned Deily,
 nad at acm.org



From kevin.p.dwyer at gmail.com  Fri Mar  7 16:05:15 2014
From: kevin.p.dwyer at gmail.com (Kev Dwyer)
Date: Fri, 07 Mar 2014 21:05:15 +0000
Subject: extract from json
References: <d72d9e78-ee11-4833-b3b2-e90ab52a6d4c@googlegroups.com>
Message-ID: <lfdc9v$bkk$1@ger.gmane.org>

teddybubu at gmail.com wrote:

> I can't find any example on how to do this.
> I have a json file like so:
> {"bostock":
[{"url":"http://bl.ocks.org/mbostock/9360565","title":"titleplaceholder","date":"dateplaceholder"},
> 
{"url":"http://bl.ocks.org/mbostock/9265674","title":"titleplaceholder","date":"dateplaceholder"},
> 
{"url":"http://bl.ocks.org/mbostock/9265467","title":"titleplaceholder","date":"dateplaceholder"},
> 
{"url":"http://bl.ocks.org/mbostock/9234731","title":"titleplaceholder","date":"dateplaceholder"},
> 
{"url":"http://bl.ocks.org/mbostock/9232962","title":"titleplaceholder","date":"dateplaceholder"},
> 
> this goes on for more than 700 entries. only thing unique is the number at
> the end of the url. I am going to load the url in python, get the date and
> title and write it in the json itself. Right now I am stuck on just
> reading the url in the json. Here is my code:
> 
> import json
> 
> with open("bostock.json") as json_file:
>     json_data = json.load(json_file)
>     print(json_data)
> 
> I have tried json_data[0], json_data.url and a few others I forget right
> now and it does not seem to work.
> 
> I have already figured out how to get the title and date.
> First things first: How can i just get the url for each line of the above
> json file?


Hello 

Try:

Python 2.7.2 (default, Aug 19 2011, 20:41:43) [GCC] on linux2                                                           
Type "help", "copyright", "credits" or "license" for more information.                                                  

>>> import  json
>>> with open('/tmp/bostock.json') as f:
...     json_data = json.load(f)
... 
>>> json_data
{u'bostock': [{u'url': u'http://bl.ocks.org/mbostock/9360565', u'date': 
u'dateplaceholder', u'title': u'titleplaceholder'}, {u'url': 
u'http://bl.ocks.org/mbostock/9265674', u'date': u'dateplaceholder', 
u'title': u'titleplaceholder'}, {u'url': 
u'http://bl.ocks.org/mbostock/9265467', u'date': u'dateplaceholder', 
u'title': u'titleplaceholder'}, {u'url': 
u'http://bl.ocks.org/mbostock/9234731', u'date': u'dateplaceholder', 
u'title': u'titleplaceholder'}, {u'url': 
u'http://bl.ocks.org/mbostock/9232962', u'date': u'dateplaceholder', 
u'title': u'titleplaceholder'}]}

>>> urls = [x['url'] for x in json_data['bostock']]
>>> urls
[u'http://bl.ocks.org/mbostock/9360565', 
u'http://bl.ocks.org/mbostock/9265674', 
u'http://bl.ocks.org/mbostock/9265467', 
u'http://bl.ocks.org/mbostock/9234731', 
u'http://bl.ocks.org/mbostock/9232962']

Python loads the json in the file into a dictionary.  In this case, the 
dictionary has a single key, 'bostock', and the value in the dictionary for 
that key is a list (of dictionaries).  

To get the urls, you need to get the list 

json_data['bostock']

 and then iterate over it's elements, getting the value for the key url for 
each one.  
This is what the list comprehension 

[x['url'] for x in json_data['bostock']]

does.

I hope that helps,

Kev




From drsalists at gmail.com  Fri Mar  7 19:15:36 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Fri, 7 Mar 2014 16:15:36 -0800
Subject: Assertions are bad, m'kay?
In-Reply-To: <5319a975$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.7890.1394176617.18130.python-list@python.org>
 <5319a975$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAGGBd_rbho4UUesBKTXLhqBaEi71Xm3ZxpZQF1rG-t1+VdppVw@mail.gmail.com>

On Fri, Mar 7, 2014 at 3:11 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:

>
> Assertions are not bad! They're just misunderstood and abused.

> You should read this guy's blog post on when to use assert:
>
> http://import-that.dreamwidth.org/676.html

Nice article.

BTW, what about:

if value >= 3:
   raise AssertionError('value must be >= 3')

?


From ben+python at benfinney.id.au  Fri Mar  7 19:22:21 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sat, 08 Mar 2014 11:22:21 +1100
Subject: Assertions are bad, m'kay?
References: <mailman.7890.1394176617.18130.python-list@python.org>
 <5319a975$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <CAGGBd_rbho4UUesBKTXLhqBaEi71Xm3ZxpZQF1rG-t1+VdppVw@mail.gmail.com>
Message-ID: <857g85wncy.fsf@benfinney.id.au>

Dan Stromberg <drsalists at gmail.com> writes:

> BTW, what about:
>
> if value >= 3:
>    raise AssertionError('value must be >= 3')

That would be very confusing, since it would only appear when the value
is >= 3. Were you making some other point?

-- 
 \        ?If this is your first visit to the USSR, you are welcome to |
  `\                                          it.? ?hotel room, Moscow |
_o__)                                                                  |
Ben Finney



From irmen.NOSPAM at xs4all.nl  Fri Mar  7 19:26:05 2014
From: irmen.NOSPAM at xs4all.nl (Irmen de Jong)
Date: Sat, 08 Mar 2014 01:26:05 +0100
Subject: Assertions are bad, m'kay?
In-Reply-To: <mailman.7909.1394237738.18130.python-list@python.org>
References: <mailman.7890.1394176617.18130.python-list@python.org>
 <5319a975$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7909.1394237738.18130.python-list@python.org>
Message-ID: <531a639b$0$2843$e4fe514c@news.xs4all.nl>

On 8-3-2014 1:15, Dan Stromberg wrote:
> On Fri, Mar 7, 2014 at 3:11 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
> 
>>
>> Assertions are not bad! They're just misunderstood and abused.
> 
>> You should read this guy's blog post on when to use assert:
>>
>> http://import-that.dreamwidth.org/676.html
> 
> Nice article.
> 
> BTW, what about:
> 
> if value >= 3:
>    raise AssertionError('value must be >= 3')
> 
> ?

I don't think this qualifies as an assertion. Also, because AssertionError is documented
as "Raised when an assert statement fails", I would never use it myself explicitly like
this.

You should use ValueError instead (or a more precise exception such as IndexError, if
appropriate).

Irmen






From missive at hotmail.com  Fri Mar  7 20:16:34 2014
From: missive at hotmail.com (Lee Harr)
Date: Sat, 8 Mar 2014 05:46:34 +0430
Subject: Function and turtle help
Message-ID: <BLU168-W26CED04F406ED375A56B62B18A0@phx.gbl>

> I am completely new to programming so thanks for any help!

Not sure it will help, and hopefully I am not self-promoting too much,
but this may be of interest to you:

http://pynguin.googlecode.com/

http://code.google.com/p/pynguin/wiki/StartProgramming


I am interested in feedback from new programmers. 		 	   		  

From swdunning at cox.net  Fri Mar  7 20:25:30 2014
From: swdunning at cox.net (Scott W Dunning)
Date: Fri, 7 Mar 2014 18:25:30 -0700
Subject: Function and turtle help
In-Reply-To: <apKp1n00b3bjUJS01pKrAP>
References: <apKp1n00b3bjUJS01pKrAP>
Message-ID: <76432E92-D563-4F97-A1C7-9F9178184428@cox.net>


On Mar 7, 2014, at 6:16 PM, Lee Harr <missive at hotmail.com> wrote:

>> I am completely new to programming so thanks for any help!
> 
> Not sure it will help, and hopefully I am not self-promoting too much,
> but this may be of interest to you:
> 
> http://pynguin.googlecode.com/
> 
> http://code.google.com/p/pynguin/wiki/StartProgramming
> 
Awesome!  Looks fun, I?ll definitely check it out and let you know!!

Scott

From greg.ewing at canterbury.ac.nz  Fri Mar  7 21:17:31 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Sat, 08 Mar 2014 15:17:31 +1300
Subject: Tuples and immutability
In-Reply-To: <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
Message-ID: <bnvctpF5vanU1@mid.individual.net>

Duncan Booth wrote:
> Is there any reason why tuples need to throw an exception on assigning to 
> the element if the old value and new value are the same object?

It would make introspection misleading, because tuples
would have a __setitem__ method event though they don't
actually support item assignment.

Also, it would solve the problem for tuples in particular,
but not for any other immutable type -- they would all
have to implement the same behaviour independently to
enjoy the benefit.

Here's another idea: If the __iadd__ method returns the
same object, *and* the LHS doesn't have a __setitem__
method, then do nothing instead of raising an exception.

Peter Otten wrote:

 > Traceback (most recent call last):
 >   File "<stdin>", line 2, in <module>
 >   File "<stdin>", line 4, in __setitem__
 > TypeError: 257 is not 257
 >
 > I'm not sure "help" is the right word here ;)

I don't think that's a problem, because the use case
being addressed is where the object performs in-place
modification and always returns itself. Any object that
doesn't return itself is not modifying in-place, even
if the returned object happens to be equal to the
original one.

-- 
Greg


From teddybubu at gmail.com  Fri Mar  7 22:02:03 2014
From: teddybubu at gmail.com (teddybubu at gmail.com)
Date: Fri, 7 Mar 2014 19:02:03 -0800 (PST)
Subject: extract from json
In-Reply-To: <mailman.7908.1394226337.18130.python-list@python.org>
References: <d72d9e78-ee11-4833-b3b2-e90ab52a6d4c@googlegroups.com>
 <mailman.7908.1394226337.18130.python-list@python.org>
Message-ID: <0d5a61a6-f765-4865-bc2f-cc34291dffd3@googlegroups.com>

On Friday, March 7, 2014 3:05:15 PM UTC-6, Kev Dwyer wrote:
>  wrote:
> > I can't find any example on how to do this.
> 
> > I have a json file like so:
> 
> > {"bostock":[{"url":"http://bl.ocks.org/mbostock/9360565","title":"titleplaceholder","date":"dateplaceholder"},{"url":"http://bl.ocks.org/mbostock/9265674","title":"titleplaceholder","date":"dateplaceholder"},{"url":"http://bl.ocks.org/mbostock/9265467","title":"titleplaceholder","date":"dateplaceholder"},{"url":"http://bl.ocks.org/mbostock/9234731","title":"titleplaceholder","date":"dateplaceholder"},{"url":"http://bl.ocks.org/mbostock/9232962","title":"titleplaceholder","date":"dateplaceholder"},
> > this goes on for more than 700 entries. only thing unique is the number at
> 
> > the end of the url. I am going to load the url in python, get the date and
> 
> > title and write it in the json itself. Right now I am stuck on just
> 
> > reading the url in the json. Here is my code:
> > import json
> > with open("bostock.json") as json_file:
> 
> >     json_data = json.load(json_file)
> 
> >     print(json_data)
> > I have tried json_data[0], json_data.url and a few others I forget right
> 
> > now and it does not seem to work.
> > I have already figured out how to get the title and date.
> 
> > First things first: How can i just get the url for each line of the above
> 
> > json file?
> Hello 
> Try:
> 
> Python 2.7.2 (default, Aug 19 2011, 20:41:43) [GCC] on linux2                                                           
> 
> Type "help", "copyright", "credits" or "license" for more information.                                                  

> >>> import  json
> 
> >>> with open('/tmp/bostock.json') as f:
> 
> ...     json_data = json.load(f)
> >>> json_data
> {u'bostock': [{u'url': u'http://bl.ocks.org/mbostock/9360565', u'date': 
> u'dateplaceholder', u'title': u'titleplaceholder'}, {u'url': 
> u'http://bl.ocks.org/mbostock/9265674', u'date': u'dateplaceholder', 
> u'title': u'titleplaceholder'}, {u'url': 
> u'http://bl.ocks.org/mbostock/9265467', u'date': u'dateplaceholder', 
> 
> u'title': u'titleplaceholder'}, {u'url': 
> 
> u'http://bl.ocks.org/mbostock/9234731', u'date': u'dateplaceholder', 
> u'title': u'titleplaceholder'}, {u'url': 
> u'http://bl.ocks.org/mbostock/9232962', u'date': u'dateplaceholder', 
> u'title': u'titleplaceholder'}]} 
> >>> urls = [x['url'] for x in json_data['bostock']]
> 
> >>> urls
> 
> [u'http://bl.ocks.org/mbostock/9360565', 
> 
> u'http://bl.ocks.org/mbostock/9265674', 
> 
> u'http://bl.ocks.org/mbostock/9265467', 
> 
> u'http://bl.ocks.org/mbostock/9234731', 

> u'http://bl.ocks.org/mbostock/9232962']
 
> Python loads the json in the file into a dictionary.  In this case, the 
> dictionary has a single key, 'bostock', and the value in the dictionary for 
 
> that key is a list (of dictionaries).  

> To get the urls, you need to get the list 
 
> json_data['bostock']
>  and then iterate over it's elements, getting the value for the key url for 
 > each one.  
> This is what the list comprehension 
> [x['url'] for x in json_data['bostock']]
> does.
> I hope that helps, 
> Kev

Kev your the man. Thanks


From thrinaxodon666 at gmail.com  Fri Mar  7 22:21:16 2014
From: thrinaxodon666 at gmail.com (thrinaxodon666 at gmail.com)
Date: Fri, 7 Mar 2014 19:21:16 -0800 (PST)
Subject: extract from json
In-Reply-To: <d72d9e78-ee11-4833-b3b2-e90ab52a6d4c@googlegroups.com>
References: <d72d9e78-ee11-4833-b3b2-e90ab52a6d4c@googlegroups.com>
Message-ID: <c80f6c49-ac85-4ba4-8ca9-b305a1f4f84e@googlegroups.com>

On Friday, March 7, 2014 3:27:27 PM UTC-5, tedd... at gmail.com wrote:
> I can't find any example on how to do this.
> 
> I have a json file like so:
> 
> {"bostock":[{"url":"http://bl.ocks.org/mbostock/9360565","title":"titleplaceholder","date":"dateplaceholder"},
> 
> {"url":"http://bl.ocks.org/mbostock/9265674","title":"titleplaceholder","date":"dateplaceholder"},
> 
> {"url":"http://bl.ocks.org/mbostock/9265467","title":"titleplaceholder","date":"dateplaceholder"},
> 
> {"url":"http://bl.ocks.org/mbostock/9234731","title":"titleplaceholder","date":"dateplaceholder"},
> 
> {"url":"http://bl.ocks.org/mbostock/9232962","title":"titleplaceholder","date":"dateplaceholder"},
> 
> 
> 
> this goes on for more than 700 entries. only thing unique is the number at the end of the url. I am going to load the url in python, get the date and title and write it in the json itself. 
> 
> Right now I am stuck on just reading the url in the json. Here is my code:
> 
> 
> 
> import json
> 
> 
> 
> with open("bostock.json") as json_file:
> 
>     json_data = json.load(json_file)
> 
>     print(json_data)
> 
> 
> 
> I have tried json_data[0], json_data.url and a few others I forget right now and it does not seem to work.  
> 
> 
> 
> I have already figured out how to get the title and date.
> 
> First things first: How can i just get the url for each line of the above json file?

I think it's better if you f*ck off.


From thrinaxodon666 at gmail.com  Fri Mar  7 22:24:23 2014
From: thrinaxodon666 at gmail.com (thrinaxodon666 at gmail.com)
Date: Fri, 7 Mar 2014 19:24:23 -0800 (PST)
Subject: -- redacted --
Message-ID: <1b3148bd-dfa3-49e1-920d-9832e9f58501@googlegroups.com>

-- redacted --


From wrw at mac.com  Fri Mar  7 21:46:17 2014
From: wrw at mac.com (William Ray Wing)
Date: Fri, 07 Mar 2014 21:46:17 -0500
Subject: Python programming
In-Reply-To: <560e7dcc-6557-44b8-89f7-adaafa9f0e29@googlegroups.com>
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <roy-18C608.22022011022014@news.panix.com>
 <201402112314.42370.gheskett@wdtv.com> <ldftlc$ohg$1@ger.gmane.org>
 <mailman.6815.1392256827.18130.python-list@python.org>
 <ldhcau$d9v$1@reader1.panix.com> <roy-A94C1B.22041912022014@news.panix.com>
 <82055DB9-758F-4B4C-9993-FE4DA60E3D50@mac.com>
 <mailman.6827.1392280246.18130.python-list@python.org>
 <560e7dcc-6557-44b8-89f7-adaafa9f0e29@googlegroups.com>
Message-ID: <4E03DD51-0D73-4FDD-BE60-DE060BD0B57C@mac.com>

On Mar 7, 2014, at 1:03 PM, John Ladasky <john_ladasky at sbcglobal.net> wrote:

> 
> As for FORTRAN?  This week, I actually downloaded an application which required a FORTRAN compiler.  This is the only FORTRAN application I've ever needed.  It's not old code, the first revision came out about 10 years ago.  More than once, I have queried Google with the phrase "Why isn't FORTRAN dead yet?"  For some reason, it lives on.  I can't say that I understand why.  
> -- 
> https://mail.python.org/mailman/listinfo/python-list

Well, I?d claim that for what it was designed for (FORTRAN stands for FORmula TRANslator after all), it is still pretty da*mn good.  It generates extremely fast, robust code that requires much less debugging effort than the equivalent C or C++ requires.  Most of the physicists I know still write FORTRAN, although they no longer do so exclusively.

Of course, as has been pointed out, the HUGE code base of scientific and numerical analysis code that already exists in FORTRAN makes rewriting sort of a waste of grant (or company) money.

-Bill

From rosuav at gmail.com  Fri Mar  7 22:49:38 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 8 Mar 2014 14:49:38 +1100
Subject: extract from json
In-Reply-To: <c80f6c49-ac85-4ba4-8ca9-b305a1f4f84e@googlegroups.com>
References: <d72d9e78-ee11-4833-b3b2-e90ab52a6d4c@googlegroups.com>
 <c80f6c49-ac85-4ba4-8ca9-b305a1f4f84e@googlegroups.com>
Message-ID: <CAPTjJmqf_q=-7e3hgKWO50MBhvronkV1p6_-Qf6Gbei_G6=w2g@mail.gmail.com>

On Sat, Mar 8, 2014 at 2:21 PM,  <thrinaxodon666 at gmail.com> wrote:
> I think it's better if you (CENSORED) off.

Teddybubu, please understand that the above comment is from a spammer
and does not reflect the prevailing attitude of this list. I don't
like to make content-free posts like this, but as you already have the
answer you need, there's not a lot for me to add :)

ChrisA


From ian.g.kelly at gmail.com  Fri Mar  7 23:17:14 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 7 Mar 2014 21:17:14 -0700
Subject: Tuples and immutability
In-Reply-To: <bnvctpF5vanU1@mid.individual.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
Message-ID: <CALwzid=ASusEfmYwasS-wDEj0SK9T+LjnFmq27DEqxf3mE8UvA@mail.gmail.com>

On Fri, Mar 7, 2014 at 7:17 PM, Gregory Ewing
<greg.ewing at canterbury.ac.nz> wrote:
> Here's another idea: If the __iadd__ method returns the
> same object, *and* the LHS doesn't have a __setitem__
> method, then do nothing instead of raising an exception.

Maybe it doesn't have a __setitem__ because the object that was
retrieved is computed rather than stored, and the result of the
__iadd__ will simply be discarded.  Somewhat contrived example:

class LessThanFilter:

    def __init__(self, the_list):
        self._the_list = the_list

    def __getitem__(self, bound):
        return [x for x in self._the_list if x < bound]


filter = LessThanFilter([10, 20, 30, 40, 50])
filter[25] += [15, 17, 23]

Should that last line not raise an exception?  The __iadd__ call will
return the same object, and the LHS doesn't have a __setitem__ method.

> I don't think that's a problem, because the use case
> being addressed is where the object performs in-place
> modification and always returns itself. Any object that
> doesn't return itself is not modifying in-place, even
> if the returned object happens to be equal to the
> original one.

I already mentioned this earlier in the thread, but a balanced binary
tree might implement += as node insertion and then return a different
object if the balancing causes the root node to change.


From dieter at handshake.de  Sat Mar  8 01:45:55 2014
From: dieter at handshake.de (dieter)
Date: Sat, 08 Mar 2014 07:45:55 +0100
Subject: gdb unable to read python frame information
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <mailman.7889.1394176233.18130.python-list@python.org>
 <c583c21d-d0a2-449a-93e2-37db713b33ed@googlegroups.com>
Message-ID: <87d2hx2noc.fsf@handshake.de>

Wesley <nispray at gmail.com> writes:

> Install python from source with some special configure options?

When I last generated Python from source, there was no need
to do anything special to get debugging symbols (the option
("gcc") option "-g" was automatically included).



From dieter at handshake.de  Sat Mar  8 01:48:53 2014
From: dieter at handshake.de (dieter)
Date: Sat, 08 Mar 2014 07:48:53 +0100
Subject: debugging on windows
References: <5319CAC7.4010200@chamonix.reportlab.co.uk>
Message-ID: <878usl2nje.fsf@handshake.de>

Robin Becker <robin at reportlab.com> writes:

> Using
>
>> Python 3.3.3 (v3.3.3:c3896275c0f6, Nov 18 2013, 21:18:40) [MSC v.1600 32 bit (Intel)] on win32
>> Type "help", "copyright", "credits" or "license" for more information.
>
> to run a tkinter + pmw2 application I have the following error on windows xp sp3
>
>> Unhandled exception at 0x1e0aebb8 in python.exe: 0xC0000005: Access violation reading location 0x00000048.

This is a C level error -- likely some memory corruption.
You will need a C level debugger to analyse the problem -
and likely, it will not be easy.



From marko at pacujo.net  Sat Mar  8 03:34:06 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 08 Mar 2014 10:34:06 +0200
Subject: Balanced trees (was: Re: Tuples and immutability)
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
Message-ID: <87eh2d3x8h.fsf_-_@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> I already mentioned this earlier in the thread, but a balanced binary
> tree might implement += as node insertion and then return a different
> object if the balancing causes the root node to change.

True.

Speaking of which, are there plans to add a balanced tree to the
"batteries" of Python? Timers, cache aging and the like need it. I'm
using my own AVL tree implementation, but I'm wondering why Python
still doesn't have one.

In fact, since asyncio has timers but Python doesn't have balanced
trees, I'm led to wonder how good the asyncio implementation can be.

Note that Java "batteries" include TreeMap.


Marko


From ian.g.kelly at gmail.com  Sat Mar  8 06:03:00 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 8 Mar 2014 04:03:00 -0700
Subject: Balanced trees (was: Re: Tuples and immutability)
In-Reply-To: <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
Message-ID: <CALwzidmABZuu5J8UYsOG1qUHVQ+oEZ1VQLR4MhoWY+0y8mM5WQ@mail.gmail.com>

On Sat, Mar 8, 2014 at 1:34 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Speaking of which, are there plans to add a balanced tree to the
> "batteries" of Python? Timers, cache aging and the like need it. I'm
> using my own AVL tree implementation, but I'm wondering why Python
> still doesn't have one.

None currently that I'm aware of.  If you want to propose adding one,
I suggest reading:

http://docs.python.org/devguide/stdlibchanges.html

> In fact, since asyncio has timers but Python doesn't have balanced
> trees, I'm led to wonder how good the asyncio implementation can be.

Peeking at the code, it appears to use a heapq-based priority queue.
Why would a balanced binary tree be better?


From marko at pacujo.net  Sat Mar  8 06:26:28 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 08 Mar 2014 13:26:28 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <mailman.7924.1394276624.18130.python-list@python.org>
Message-ID: <87txb9szh7.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> Peeking at the code, it appears to use a heapq-based priority queue.
> Why would a balanced binary tree be better?

AFAIK, a heap queue doesn't allow for the deletion of a random element
forcing you to leave the canceled timers in the queue to be deleted
later.

In a very typical scenario, networking entities start timers very
frequently (depending on the load, maybe at 100..1000 Hz) but cancel
virtually every one of them, leading to some wakeup churn and extra
memory load. I don't know if the churn is better or worse than the tree
balancing overhead.

Imagine a web server that received HTTP connections. You might want to
specify a 10-minute idle timeout for the connections. In the heapq timer
implementation, your connection objects are kept in memory for 10
minutes even if they are closed gracefully because the canceled timer
maintains a reference to the object.

Of course, it may be that the heapq implementation sets the callback to
None leaving only the minimal timer object lingering and waiting to come
out of the digestive tract.


Marko


From andywu1206 at gmail.com  Sat Mar  8 07:01:40 2014
From: andywu1206 at gmail.com (Harry Wood)
Date: Sat, 8 Mar 2014 04:01:40 -0800 (PST)
Subject: How to recovery the default "Library/Python/"  folder on Mac?
Message-ID: <789955cd-1a8d-4b95-8c98-44e635fca117@googlegroups.com>


How to recovery the default "Library/Python/"  folder on Mac? 


I delete it by some mistakes..., I have tried the following steps:

    - Step 1. Download and install Python DMG from Python.org .

       Result: There are no Python folders under Library after I installed the Python DMG.

    - Step 2. I tried to use " brew install python " in Terminal.
       Result: $ brew uninstall python 
                     Error: No such keg: 


What should I need to do now? Please give me some specific directions, Thanks.


From nilsherolindemann at gmail.com  Sat Mar  8 07:44:27 2014
From: nilsherolindemann at gmail.com (Nils-Hero Lindemann)
Date: Sat, 8 Mar 2014 13:44:27 +0100
Subject: Critic: New Python Front Page
Message-ID: <20140308134427.74581920.nilsherolindemann@gmail.com>

Hi,

(Please forgive (or correct) my mistakes, i am non native)

http://www.python.org/community/sigs/retired/parser-sig/towards-standard/
* Formatting bug
* Needs breadcrumb navigation ("Where am i?")
  (i came there via http://theory.stanford.edu/~amitp/yapps/)
* blue background makes top links invisible when i look on laptop
  screen from a 60% angle. Prefer white.
* 1 third of space on y-axis is used for 15 navigation
  links and a search bar.
* 1 third of space on x-axis is used for one sentence about and a link
  to PSF.
* I can not easily get rid of this by using e.g. HackTheWeb
  (https://addons.mozilla.org/de/firefox/addon/hack-the-web/).
  Please compare with e.g. Wikipedia, it is easy there to isolate the
  main content.

http://www.python.org/community/
That picture is scary.

Regards, Nils

-- 
Nils-Hero Lindemann <nilsherolindemann at gmail.com>


From generalcosta at gmail.com  Sat Mar  8 07:53:57 2014
From: generalcosta at gmail.com (JCosta)
Date: Sat, 8 Mar 2014 04:53:57 -0800 (PST)
Subject: Python performance
Message-ID: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>

I did some work in c# and java and I converted some application to Python; I noticed Python is much slower than the other languages.

Is this normal ?
Thanks


From breamoreboy at yahoo.co.uk  Sat Mar  8 08:13:31 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 08 Mar 2014 13:13:31 +0000
Subject: spam (wasRe: extract from json)
In-Reply-To: <CAPTjJmqf_q=-7e3hgKWO50MBhvronkV1p6_-Qf6Gbei_G6=w2g@mail.gmail.com>
References: <d72d9e78-ee11-4833-b3b2-e90ab52a6d4c@googlegroups.com>
 <c80f6c49-ac85-4ba4-8ca9-b305a1f4f84e@googlegroups.com>
 <CAPTjJmqf_q=-7e3hgKWO50MBhvronkV1p6_-Qf6Gbei_G6=w2g@mail.gmail.com>
Message-ID: <lff51n$aoc$1@ger.gmane.org>

On 08/03/2014 03:49, Chris Angelico wrote:
> On Sat, Mar 8, 2014 at 2:21 PM,  <thrinaxodon666 at gmail.com> wrote:
>> I think it's better if you (CENSORED) off.
>
> Teddybubu, please understand that the above comment is from a spammer
> and does not reflect the prevailing attitude of this list. I don't
> like to make content-free posts like this, but as you already have the
> answer you need, there's not a lot for me to add :)
>
> ChrisA
>

This particular PITA of a spammer is one of the very few that I see on 
Thunderbird via gmane.  I believe that Terry Reedy amongst others does a 
good job of keeping us relatively spam free.  Thanks all.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Sat Mar  8 08:19:05 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 9 Mar 2014 00:19:05 +1100
Subject: spam (wasRe: extract from json)
In-Reply-To: <lff51n$aoc$1@ger.gmane.org>
References: <d72d9e78-ee11-4833-b3b2-e90ab52a6d4c@googlegroups.com>
 <c80f6c49-ac85-4ba4-8ca9-b305a1f4f84e@googlegroups.com>
 <CAPTjJmqf_q=-7e3hgKWO50MBhvronkV1p6_-Qf6Gbei_G6=w2g@mail.gmail.com>
 <lff51n$aoc$1@ger.gmane.org>
Message-ID: <CAPTjJmo6h+46KVRRGcLkQEt=4g2ozbzxiYq53RH28AuZqggMWQ@mail.gmail.com>

On Sun, Mar 9, 2014 at 12:13 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> On 08/03/2014 03:49, Chris Angelico wrote:
>>
>> On Sat, Mar 8, 2014 at 2:21 PM,  <thrinaxodon666 at gmail.com> wrote:
>>>
>>> I think it's better if you (CENSORED) off.
>>
>>
>> Teddybubu, please understand that the above comment is from a spammer
>> and does not reflect the prevailing attitude of this list. I don't
>> like to make content-free posts like this, but as you already have the
>> answer you need, there's not a lot for me to add :)
>>
>> ChrisA
>>
>
> This particular PITA of a spammer is one of the very few that I see on
> Thunderbird via gmane.  I believe that Terry Reedy amongst others does a
> good job of keeping us relatively spam free.  Thanks all.

Normally I ignore him (and yes, I see those posts too, in Gmail).
Stand-alone posts aren't an issue. I just didn't want a new poster to
see that reply go through unchallenged.

ChrisA


From rosuav at gmail.com  Sat Mar  8 08:24:24 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 9 Mar 2014 00:24:24 +1100
Subject: Python performance
In-Reply-To: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>
References: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>
Message-ID: <CAPTjJmoWyXX5ODEk_Ccmh1MpgWOn0NUY=xEVAeRa0yjYGMXkKQ@mail.gmail.com>

On Sat, Mar 8, 2014 at 11:53 PM, JCosta <generalcosta at gmail.com> wrote:
> I did some work in c# and java and I converted some application to Python; I noticed Python is much slower than the other languages.
>
> Is this normal ?
> Thanks

The first thing to look at is the conversion. If you convert idiomatic
Java code into the nearest-equivalent Python, it won't be idiomatic
Python, and it'll probably underperform. (This is especially true if
you create a whole lot of objects, use long chains of classes with
dots, and so on. Java follows dotted name chains at compile time,
Python does at run time.)

Another thing to consider is that Python, while very convenient, isn't
always the fastest at heavy numerical computation. For that, there are
some dedicated libraries, like NumPy, which can do that for you.

But it's also worth checking whether the speed difference even
matters. Are you able to see a real difference, as a human, or is this
just benchmarks? It's not a problem for something to take 5ms in
Python that would take 2ms in Java, if that time is spent responding
to a user's click - the user won't see that difference!

If you post a bit of code, we can help you to see what's going on.
Best bit of code to post would be the slowest - and since you're
talking about performance, you _have_ profiled your code and found
which bit's the slowest, right? :)

ChrisA


From ned at nedbatchelder.com  Sat Mar  8 08:31:31 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Sat, 08 Mar 2014 08:31:31 -0500
Subject: Critic: New Python Front Page
In-Reply-To: <20140308134427.74581920.nilsherolindemann@gmail.com>
References: <20140308134427.74581920.nilsherolindemann@gmail.com>
Message-ID: <lff632$jp7$1@ger.gmane.org>

On 3/8/14 7:44 AM, Nils-Hero Lindemann wrote:
> Hi,
>
> (Please forgive (or correct) my mistakes, i am non native)
>
> http://www.python.org/community/sigs/retired/parser-sig/towards-standard/
> * Formatting bug
> * Needs breadcrumb navigation ("Where am i?")
>    (i came there via http://theory.stanford.edu/~amitp/yapps/)
> * blue background makes top links invisible when i look on laptop
>    screen from a 60% angle. Prefer white.
> * 1 third of space on y-axis is used for 15 navigation
>    links and a search bar.
> * 1 third of space on x-axis is used for one sentence about and a link
>    to PSF.
> * I can not easily get rid of this by using e.g. HackTheWeb
>    (https://addons.mozilla.org/de/firefox/addon/hack-the-web/).
>    Please compare with e.g. Wikipedia, it is easy there to isolate the
>    main content.
>
> http://www.python.org/community/
> That picture is scary.
>
> Regards, Nils
>

The source for the site is on github, and they are taking and resolving 
issues there: https://github.com/python/pythondotorg/issues

-- 
Ned Batchelder, http://nedbatchelder.com



From nispray at gmail.com  Sat Mar  8 08:31:38 2014
From: nispray at gmail.com (Wesley)
Date: Sat, 8 Mar 2014 05:31:38 -0800 (PST)
Subject: gdb unable to read python frame information
In-Reply-To: <mailman.7907.1394225249.18130.python-list@python.org>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <mailman.7889.1394176233.18130.python-list@python.org>
 <c583c21d-d0a2-449a-93e2-37db713b33ed@googlegroups.com>
 <mailman.7907.1394225249.18130.python-list@python.org>
Message-ID: <25473c34-fbc6-4e81-ad6d-c86f12f7b72e@googlegroups.com>

1. install gdb from source with configure option --with-python

2. install python from source with configure option --with-pydebug

3. Got error in gdb here:
2.6.6 (r266:84292, Jan 22 2014, 09:42:36) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)]
(gdb) py-bt
Undefined command: "py-bt".  Try "help".
(gdb) python
>import libpython
>end
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/share/gdb/python/libpython.py", line 49, in <module>
    _type_size_t = gdb.lookup_type('size_t')
gdb.error: No type named size_t.
Error while executing Python code.
(gdb) 


From nispray at gmail.com  Sat Mar  8 08:32:30 2014
From: nispray at gmail.com (Wesley)
Date: Sat, 8 Mar 2014 05:32:30 -0800 (PST)
Subject: gdb unable to read python frame information
In-Reply-To: <mailman.7900.1394198618.18130.python-list@python.org>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <87mwh2bi1v.fsf@handshake.de>
 <mailman.7900.1394198618.18130.python-list@python.org>
Message-ID: <73e3cfa2-28d3-4647-8a7f-577e41dffbd1@googlegroups.com>

python debuginfo is installed...
Still,py-bt, py-locals.etc cannot read python frame


From python.list at tim.thechases.com  Sat Mar  8 08:40:48 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Sat, 8 Mar 2014 07:40:48 -0600
Subject: Python performance
In-Reply-To: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>
References: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>
Message-ID: <20140308074048.3e7b1cd6@bigbox.christie.dr>

On 2014-03-08 04:53, JCosta wrote:
> I did some work in c# and java and I converted some application to
> Python; I noticed Python is much slower than the other languages.
> 
> Is this normal ?

It depends.

Did you write C#/Java in Python (i.e., use C# or Java idioms in
Python), or did you write Pythonic code?

Check your algorithms and storage classes for performance
characteristics (if you used an O(1) algorithm/container in C#/Java
but used an O(N) algorithm/container in Python) and make sure they
match.

What sorts of operations are you doing?  Are you CPU-bound, I/O
bound, or memory-bound?  Have you profiled to see where the hot-spots
are?

Personally, I've found that most of my code is I/O-bound (disk or
network), and that very rarely has CPU been much of a problem
(usually checking my algorithm if there's trouble; occasionally I'm
stuck with an O(N^2) algorithm and no language-choice.  For some
folks, using one of the specialty-math libraries can speed up numeric
processing.  If I know that memory could be an issue, I tend to switch
to a disk-based data-stores to head off any trouble.

-tkc






From ned at nedbatchelder.com  Sat Mar  8 09:11:26 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Sat, 08 Mar 2014 09:11:26 -0500
Subject: Critic: New Python Front Page
In-Reply-To: <lff632$jp7$1@ger.gmane.org>
References: <20140308134427.74581920.nilsherolindemann@gmail.com>
 <lff632$jp7$1@ger.gmane.org>
Message-ID: <lff8ds$ct1$1@ger.gmane.org>

On 3/8/14 8:31 AM, Ned Batchelder wrote:
> On 3/8/14 7:44 AM, Nils-Hero Lindemann wrote:
>> Hi,
>>
>> (Please forgive (or correct) my mistakes, i am non native)
>>
>> http://www.python.org/community/sigs/retired/parser-sig/towards-standard/
>> * Formatting bug
>> * Needs breadcrumb navigation ("Where am i?")
>>    (i came there via http://theory.stanford.edu/~amitp/yapps/)
>> * blue background makes top links invisible when i look on laptop
>>    screen from a 60% angle. Prefer white.
>> * 1 third of space on y-axis is used for 15 navigation
>>    links and a search bar.
>> * 1 third of space on x-axis is used for one sentence about and a link
>>    to PSF.
>> * I can not easily get rid of this by using e.g. HackTheWeb
>>    (https://addons.mozilla.org/de/firefox/addon/hack-the-web/).
>>    Please compare with e.g. Wikipedia, it is easy there to isolate the
>>    main content.
>>
>> http://www.python.org/community/
>> That picture is scary.
>>
>> Regards, Nils
>>
>
> The source for the site is on github, and they are taking and resolving
> issues there: https://github.com/python/pythondotorg/issues
>

Also, I agree with you about the picture on the community page: 
https://github.com/python/pythondotorg/issues/265

-- 
Ned Batchelder, http://nedbatchelder.com



From breamoreboy at yahoo.co.uk  Sat Mar  8 09:14:12 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 08 Mar 2014 14:14:12 +0000
Subject: gdb unable to read python frame information
In-Reply-To: <73e3cfa2-28d3-4647-8a7f-577e41dffbd1@googlegroups.com>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <87mwh2bi1v.fsf@handshake.de>
 <mailman.7900.1394198618.18130.python-list@python.org>
 <73e3cfa2-28d3-4647-8a7f-577e41dffbd1@googlegroups.com>
Message-ID: <lff8jg$d9e$1@ger.gmane.org>

On 08/03/2014 13:32, Wesley wrote:
> python debuginfo is installed...
> Still,py-bt, py-locals.etc cannot read python frame
>

If you don't provide context people are less likely to help you.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From steve+comp.lang.python at pearwood.info  Sat Mar  8 09:44:23 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 08 Mar 2014 14:44:23 GMT
Subject: Assertions are bad, m'kay?
References: <mailman.7890.1394176617.18130.python-list@python.org>
 <5319a975$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7909.1394237738.18130.python-list@python.org>
Message-ID: <531b2cc7$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Fri, 07 Mar 2014 16:15:36 -0800, Dan Stromberg wrote:

> On Fri, Mar 7, 2014 at 3:11 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
> 
> 
>> Assertions are not bad! They're just misunderstood and abused.
> 
>> You should read this guy's blog post on when to use assert:
>>
>> http://import-that.dreamwidth.org/676.html
> 
> Nice article.
> 
> BTW, what about:
> 
> if value >= 3:
>    raise AssertionError('value must be >= 3')
> 
> ?

The error message is misleading. But you've probably noticed that by 
now :-)

What about it? Since it's missing any context, it could be a good use of 
an exception or a terrible use. Where does value come from? Why is there 
a restriction on the value?

As I see it, there are likely two reasons for writing such a test:

1) You're testing a value that comes from the user, or some 
   library you don't control; or

2) You're testing some internal invariant, a contract between 
   two parts of your own code, a piece of internal logic, etc.


In the first case, I don't think you should raise AssertionError. A 
ValueError would be more appropriate.

In the second case, using an assert might be better, since that gives you 
the opportunity to remove it at compile-time, if you choose.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From nispray at gmail.com  Sat Mar  8 09:55:32 2014
From: nispray at gmail.com (Wesley)
Date: Sat, 8 Mar 2014 06:55:32 -0800 (PST)
Subject: gdb unable to read python frame information
In-Reply-To: <25473c34-fbc6-4e81-ad6d-c86f12f7b72e@googlegroups.com>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <mailman.7889.1394176233.18130.python-list@python.org>
 <c583c21d-d0a2-449a-93e2-37db713b33ed@googlegroups.com>
 <mailman.7907.1394225249.18130.python-list@python.org>
 <25473c34-fbc6-4e81-ad6d-c86f12f7b72e@googlegroups.com>
Message-ID: <6b804c8f-2bd9-45cb-95e4-6c8524de5a28@googlegroups.com>

Now I use gdb python -p <pid>
then, import libpython
py-bt is null, py-locals raise here:
Unable to locate python frame

What's going on...


From nispray at gmail.com  Sat Mar  8 10:01:52 2014
From: nispray at gmail.com (Wesley)
Date: Sat, 8 Mar 2014 07:01:52 -0800 (PST)
Subject: gdb unable to read python frame information
In-Reply-To: <mailman.7932.1394288074.18130.python-list@python.org>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <87mwh2bi1v.fsf@handshake.de>
 <mailman.7900.1394198618.18130.python-list@python.org>
 <73e3cfa2-28d3-4647-8a7f-577e41dffbd1@googlegroups.com>
 <mailman.7932.1394288074.18130.python-list@python.org>
Message-ID: <6dc8a38d-d3a6-44fd-8f39-f73cea1ac4c1@googlegroups.com>

So, let me clarify here, in order to try, I get a clean machine.

Centos 6.5 64bit.
Now , I try this:
1. install gdb 7.7 from source , with configure option --with-python

2. install python 2.6.6 from source, with configure option --with-pydebug

3. run a python script

4. from command line, gdb python -p <pid> to attach the running script

5. within gdb, issue python, import libpython, end 
  no errors
6. py-bt outputs nothing, py-locals says Unable to locate python frame
here is the snippet:
[root at localhost Python-2.6.6]# gdb python 52315
GNU gdb (GDB) 7.7
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from python...done.
Attaching to program: /home/nipen/test/Python-2.6.6/python, process 52315
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
0x00000030a98e15c3 in ?? ()
(gdb) bt
#0  0x00000030a98e15c3 in ?? ()
#1  0x00007f4cf68d1219 in ?? ()
#2  0x0000000000000000 in ?? ()
(gdb) py-bt
Undefined command: "py-bt".  Try "help".
(gdb) python
>import libpython
>end
(gdb) py-bt
(gdb) 
(gdb) py-locals
Unable to locate python frame
(gdb) 
Unable to locate python frame


From nilsherolindemann at gmail.com  Sat Mar  8 10:52:22 2014
From: nilsherolindemann at gmail.com (Nils-Hero Lindemann)
Date: Sat, 8 Mar 2014 16:52:22 +0100
Subject: Critic: New Python Front Page
References: <20140308134427.74581920.nilsherolindemann@gmail.com>
 <lff632$jp7$1@ger.gmane.org>
 <mailman.7931.1394287896.18130.python-list@python.org>
Message-ID: <20140308165222.60e40d06.nilsherolindemann@gmail.com>

Hello,

> The source for the site is on github, and they are taking and resolving
> issues there: https://github.com/python/pythondotorg/issues

Thanks for pointing me to the right place. I copypasted my mail to ...
https://github.com/python/pythondotorg/issues/266

also i added a comment to ...
https://github.com/python/pythondotorg/issues/265

Regards, Nils


-- 
Nils-Hero Lindemann <nilsherolindemann at gmail.com>


From jsf80238 at gmail.com  Sat Mar  8 11:55:35 2014
From: jsf80238 at gmail.com (Jason Friedman)
Date: Sat, 8 Mar 2014 09:55:35 -0700
Subject: How to extract contents of inner text of html tag?
In-Reply-To: <1393697458.5147.YahooMailNeo@web126004.mail.ne1.yahoo.com>
References: <1393697458.5147.YahooMailNeo@web126004.mail.ne1.yahoo.com>
Message-ID: <CANy1k1gz8RBcygyPcici65owDGxoOdnTFV+Ty74MxxQbf=BitA@mail.gmail.com>

> for line in all_kbd:
>    if line.string == None:

I modified your code slightly:
for line in all_kbd:
    print(line)
    sys.exit()
    if line.string == None:

Running the new script yields:
$ python shibly.py
<kbd class="command">
    cp -v --remove-destination /usr/share/zoneinfo/
    <em class="replaceable"><code><xxx></xxx></code></em>
       \
    /etc/localtime
</kbd>

Meaning that
all_kbd=soup.find_all('kbd')

yields only a single string, not multiple strings as I'm guessing you expected.

You might also consider running your program as:

python -m pdb your_program.py


From marko at pacujo.net  Sat Mar  8 12:48:14 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 08 Mar 2014 19:48:14 +0200
Subject: Python performance
References: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>
Message-ID: <87lhwktwdd.fsf@elektro.pacujo.net>

JCosta <generalcosta at gmail.com>:

> I did some work in c# and java and I converted some application to
> Python; I noticed Python is much slower than the other languages.
>
> Is this normal ?

Yes. The main reason is the dot notation, which in C through Java is
implemented by the compiler as a fixed offset to a memory structure.
High-level programming languages such as Python implement it through a
hash table lookup.

That's the price of keeping everything dynamic: the structural content
is free to change any time during the execution of the program. I have
heard (but not experienced first-hand) that some ingenious heuristic
optimizations have made Common Lisp code come close to C-style
performance. Google was gung ho about repeating the feat on Python, but
seem to have given up.

The second costly specialty of Python is the way objects are
instantiated. Each object is given a "personalized" dispatch table. That
costs time and memory but is extremely nice for the programmer.

In a word, Python is a godsend if its performance is good enough for
your needs. For other needs, you have other programming languages, and
you buy the performance dearly.

Java is a great programming language, as C# must also be. However, for
the needs where you need to drop out of Python, one must ask if you
weren't better off writing some core parts in C and integrating them
with Python.


Marko


From generalcosta at gmail.com  Sat Mar  8 13:30:18 2014
From: generalcosta at gmail.com (JCosta)
Date: Sat, 8 Mar 2014 10:30:18 -0800 (PST)
Subject: Python performance
In-Reply-To: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>
References: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>
Message-ID: <d8f065b8-6ed3-47ff-8239-b059804aa785@googlegroups.com>

S?bado, 8 de Mar?o de 2014 12:53:57 UTC, JCosta escreveu:
> I did some work in c# and java and I converted some application to Python; I noticed Python is much slower than the other languages.
> 
> 
> 
> Is this normal ?
> 
> Thanks

...............

Thanks for the help (Chris, Tim and Marko) and  it?s clear now for me ...


From breamoreboy at yahoo.co.uk  Sat Mar  8 13:49:38 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 08 Mar 2014 18:49:38 +0000
Subject: Python performance
In-Reply-To: <d8f065b8-6ed3-47ff-8239-b059804aa785@googlegroups.com>
References: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>
 <d8f065b8-6ed3-47ff-8239-b059804aa785@googlegroups.com>
Message-ID: <lffonv$lns$1@ger.gmane.org>

On 08/03/2014 18:30, JCosta wrote:
> S?bado, 8 de Mar?o de 2014 12:53:57 UTC, JCosta escreveu:
>> I did some work in c# and java and I converted some application to Python; I noticed Python is much slower than the other languages.
>>
>>
>>
>> Is this normal ?
>>
>> Thanks
>
> ...............
>
> Thanks for the help (Chris, Tim and Marko) and  it?s clear now for me ...
>

You might like to check this out 
https://wiki.python.org/moin/PythonSpeed/PerformanceTips

Would you also please read and action this 
https://wiki.python.org/moin/GoogleGroupsPython to prevent us seeing the 
double line spacing and single line paragraphs above, thanks.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ned at nedbatchelder.com  Sat Mar  8 13:56:04 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Sat, 08 Mar 2014 13:56:04 -0500
Subject: Python performance
In-Reply-To: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>
References: <290bb6ed-a17e-45e3-8ff7-e58bb50e66a6@googlegroups.com>
Message-ID: <lffp3m$q91$1@ger.gmane.org>

On 3/8/14 7:53 AM, JCosta wrote:
> I did some work in c# and java and I converted some application to Python; I noticed Python is much slower than the other languages.
>
> Is this normal ?
> Thanks
>

Your question, and the replies so far in this thread, have overlooked 
the difference between language and implementation.  Python as a 
language has no inherent speed.  Your question is really about CPython, 
the reference and most-common implementation of the language.  It 
interprets virtual-machine bytecode, and so will pay a penalty for 
compute-bound code.

But PyPy is another implementation of Python.  It uses a JIT to produce 
native code automatically, and can impressively speed up the execution 
of Python programs.  You should give it a try to see if it will help in 
your situation.

-- 
Ned Batchelder, http://nedbatchelder.com



From drsalists at gmail.com  Sat Mar  8 14:58:25 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Sat, 8 Mar 2014 11:58:25 -0800
Subject: Balanced trees (was: Re: Tuples and immutability)
In-Reply-To: <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
Message-ID: <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>

On Sat, Mar 8, 2014 at 12:34 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Ian Kelly <ian.g.kelly at gmail.com>:
>
>> I already mentioned this earlier in the thread, but a balanced binary
>> tree might implement += as node insertion and then return a different
>> object if the balancing causes the root node to change.
>
> True.
>
> Speaking of which, are there plans to add a balanced tree to the
> "batteries" of Python? Timers, cache aging and the like need it. I'm
> using my own AVL tree implementation, but I'm wondering why Python
> still doesn't have one.

I think it'd probably be a good idea to add one or more balanced
binary trees to the standard library.  But I suspect it's been tried
before, and didn't happen.  It might be good to add an _un_balanced
tree too, since they do quite well with random keys.

Here's a performance comparison I did of a bunch of tree types in Python:
http://stromberg.dnsalias.org/~strombrg/python-tree-and-heap-comparison/2014-01/


From breamoreboy at yahoo.co.uk  Sat Mar  8 15:37:58 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 08 Mar 2014 20:37:58 +0000
Subject: Balanced trees
In-Reply-To: <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
Message-ID: <lffv32$mqo$1@ger.gmane.org>

On 08/03/2014 19:58, Dan Stromberg wrote:
> On Sat, Mar 8, 2014 at 12:34 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> Ian Kelly <ian.g.kelly at gmail.com>:
>>
>>> I already mentioned this earlier in the thread, but a balanced binary
>>> tree might implement += as node insertion and then return a different
>>> object if the balancing causes the root node to change.
>>
>> True.
>>
>> Speaking of which, are there plans to add a balanced tree to the
>> "batteries" of Python? Timers, cache aging and the like need it. I'm
>> using my own AVL tree implementation, but I'm wondering why Python
>> still doesn't have one.
>
> I think it'd probably be a good idea to add one or more balanced
> binary trees to the standard library.  But I suspect it's been tried
> before, and didn't happen.  It might be good to add an _un_balanced
> tree too, since they do quite well with random keys.
>
> Here's a performance comparison I did of a bunch of tree types in Python:
> http://stromberg.dnsalias.org/~strombrg/python-tree-and-heap-comparison/2014-01/
>

I've found this link useful http://kmike.ru/python-data-structures/

I also don't want all sorts of data structures added to the Python 
library.  I believe that there are advantages to leaving specialist data 
structures on pypi or other sites, plus it means Python in a Nutshell 
can still fit in your pocket and not a 40 ton articulated lorry, unlike 
the Java equivalent.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From marko at pacujo.net  Sat Mar  8 16:21:34 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 08 Mar 2014 23:21:34 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
Message-ID: <87eh2ctmht.fsf@elektro.pacujo.net>

Mark Lawrence <breamoreboy at yahoo.co.uk>:

> I believe that there are advantages to leaving specialist data
> structures on pypi or other sites, plus it means Python in a Nutshell
> can still fit in your pocket and not a 40 ton articulated lorry,
> unlike the Java equivalent.

An ordered map is a foundational data structure as opposed to, say, a
priority queue, let alone something like urllib2.

If I had to choose between a hash table and AVL (or RB) tree in the
standard library, it would definitely have to be the latter. It is more
generally usable, has fewer corner cases and probably has an equal
performance even in hash tables' sweet spot.


Marko


From john_ladasky at sbcglobal.net  Sat Mar  8 17:06:28 2014
From: john_ladasky at sbcglobal.net (John Ladasky)
Date: Sat, 8 Mar 2014 14:06:28 -0800 (PST)
Subject: Python programming
In-Reply-To: <mailman.7912.1394239141.18130.python-list@python.org>
References: <b2db52b0-d7f7-43dd-9ddf-86feb109ebc8@googlegroups.com>
 <roy-18C608.22022011022014@news.panix.com>
 <201402112314.42370.gheskett@wdtv.com> <ldftlc$ohg$1@ger.gmane.org>
 <mailman.6815.1392256827.18130.python-list@python.org>
 <ldhcau$d9v$1@reader1.panix.com> <roy-A94C1B.22041912022014@news.panix.com>
 <82055DB9-758F-4B4C-9993-FE4DA60E3D50@mac.com>
 <mailman.6827.1392280246.18130.python-list@python.org>
 <560e7dcc-6557-44b8-89f7-adaafa9f0e29@googlegroups.com>
 <mailman.7912.1394239141.18130.python-list@python.org>
Message-ID: <15357a67-2359-4c56-afcb-f8b90fbedb8e@googlegroups.com>

On Friday, March 7, 2014 4:38:54 PM UTC-8, Dennis Lee Bieber wrote:
> On Fri, 7 Mar 2014 10:03:35 -0800 (PST), John Ladasky
> <j... at sbcglobal.net> declaimed the following:
> 
>>   More than once, I have queried Google with the phrase "Why isn't FORTRAN
>> dead yet?"  For some reason, it lives on.  I can't say that I understand
>> why.  
>
> 	Well, for one thing, no one can justify rewriting all the numerics
> libraries... LAPACK http://en.wikipedia.org/wiki/LAPACK , NEC-2
> http://en.wikipedia.org/wiki/Numerical_Electromagnetics_Code (and likely
> NEC-4).

I have used Numpy for years, and I'm pretty sure that Numpy calls LAPACK under the hood.  But if that is true, then I get LAPACK as a pre-compiled binary.  I didn't need a FORTRAN compiler until last week.

If one or two specialized applications are the only reason we are keeping a 50 year-old programming language around, I would be tempted to rewrite those applications -- in C, at least.  C's not dead yet!  (It's just resting!)


From roy at panix.com  Sat Mar  8 17:22:49 2014
From: roy at panix.com (Roy Smith)
Date: Sat, 08 Mar 2014 17:22:49 -0500
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
Message-ID: <roy-4FBE95.17224908032014@news.panix.com>

In article <87eh2ctmht.fsf at elektro.pacujo.net>,
 Marko Rauhamaa <marko at pacujo.net> wrote:

> If I had to choose between a hash table and AVL (or RB) tree in the
> standard library, it would definitely have to be the latter. It is more
> generally usable, has fewer corner cases and probably has an equal
> performance even in hash tables' sweet spot.

The C++ folks made that decision, and people spent the next 10 years 
complaining, "Why is there no hash table in STL?"


From greg.ewing at canterbury.ac.nz  Sat Mar  8 19:40:28 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Sun, 09 Mar 2014 13:40:28 +1300
Subject: Tuples and immutability
In-Reply-To: <mailman.7920.1394252278.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
Message-ID: <bo1rjpFll5mU1@mid.individual.net>

Ian Kelly wrote:
> class LessThanFilter:
> 
>     def __init__(self, the_list):
>         self._the_list = the_list
> 
>     def __getitem__(self, bound):
>         return [x for x in self._the_list if x < bound]
> 
> 
> filter = LessThanFilter([10, 20, 30, 40, 50])
> filter[25] += [15, 17, 23]
> 
> Should that last line not raise an exception?

In this case it will fail to catch what is probably an error,
but you can't expect the language to find all your bugs for
you. If you wrote the same bug this way:

    filter[25].extend([15, 17, 23])

it wouldn't be caught either.

What's happening is that we're trying to use the syntax
a += b to mean two different things:

1) Shorthand for a = a + b

2) A way of expressing an in-place modification, such
    as a.extend(b)

Case (2) is not really an assignment at all, so arguably
it shouldn't require the LHS to support assignment.

-- 
Greg


From greg.ewing at canterbury.ac.nz  Sat Mar  8 19:45:04 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Sun, 09 Mar 2014 13:45:04 +1300
Subject: Tuples and immutability
In-Reply-To: <mailman.7920.1394252278.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
Message-ID: <bo1rseFlmgoU1@mid.individual.net>

Ian Kelly wrote:

> I already mentioned this earlier in the thread, but a balanced binary
> tree might implement += as node insertion and then return a different
> object if the balancing causes the root node to change.

That would be a really bad way to design a binary tree
implementation. What if there is another reference to
the tree somewhere? It's still going to be referring to
the old root object, and will have an incoherent view
of the data -- partly old and partly new.

If you're going to have a mutable tree, it needs to be
encapsulated in a stable top-level object.

-- 
Greg


From drsalists at gmail.com  Sat Mar  8 20:31:26 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Sat, 8 Mar 2014 17:31:26 -0800
Subject: Balanced trees
In-Reply-To: <87eh2ctmht.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
Message-ID: <CAGGBd_q9MmKm_xLdKywRZkYqTRbK04jZZ4Vhbt8XNKXmF7tqwg@mail.gmail.com>

On Sat, Mar 8, 2014 at 1:21 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> If I had to choose between a hash table and AVL (or RB) tree in the
> standard library, it would definitely have to be the latter. It is more
> generally usable, has fewer corner cases and probably has an equal
> performance even in hash tables' sweet spot.

Actually, in the performance comparison I mentioned previously, I
compared Python dict's to a bunch of different balanced trees and one
unbalanced tree. The dictionary was much faster, though granted, it
was the only one in C.

That URL again:
http://stromberg.dnsalias.org/~strombrg/python-tree-and-heap-comparison/2014-01/


From drsalists at gmail.com  Sat Mar  8 21:08:38 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Sat, 8 Mar 2014 18:08:38 -0800
Subject: How is unicode implemented behind the scenes?
Message-ID: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>

OK, I know that Unicode data is stored in an encoding on disk.

But how is it stored in RAM?

I realize I shouldn't write code that depends on any relevant
implementation details, but knowing some of the more common
implementation options would probably help build an intuition for
what's going on internally.

I've heard that characters are no longer all c bytes wide internally,
so is it sometimes utf-8?

Thanks.


From python at mrabarnett.plus.com  Sat Mar  8 21:40:28 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Sun, 09 Mar 2014 02:40:28 +0000
Subject: How is unicode implemented behind the scenes?
In-Reply-To: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>
References: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>
Message-ID: <531BD49C.4090602@mrabarnett.plus.com>

On 2014-03-09 02:08, Dan Stromberg wrote:
> OK, I know that Unicode data is stored in an encoding on disk.
>
> But how is it stored in RAM?
>
> I realize I shouldn't write code that depends on any relevant
> implementation details, but knowing some of the more common
> implementation options would probably help build an intuition for
> what's going on internally.
>
> I've heard that characters are no longer all c bytes wide internally,
> so is it sometimes utf-8?
>
No.

 From Python 3.3, it's an array of 1, 2 or 4 bytes per codepoint.

In Python terms:

if all(c <= '\xFF' for c in string):
     use 1 byte per codepoint
elif all(c <= '\xFFFF' for c in string):
     use 2 bytes per codepoint
else:
     use 4 bytes per codepoint



From ian.g.kelly at gmail.com  Sat Mar  8 21:39:50 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 8 Mar 2014 19:39:50 -0700
Subject: Tuples and immutability
In-Reply-To: <bo1rjpFll5mU1@mid.individual.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
Message-ID: <CALwzidnryqewLPBBv=-a4eUz+BiU9snSZ49irJ0WNJaSm3i9Fw@mail.gmail.com>

On Sat, Mar 8, 2014 at 5:40 PM, Gregory Ewing
<greg.ewing at canterbury.ac.nz> wrote:
> Ian Kelly wrote:
>>
>> class LessThanFilter:
>>
>>     def __init__(self, the_list):
>>         self._the_list = the_list
>>
>>     def __getitem__(self, bound):
>>         return [x for x in self._the_list if x < bound]
>>
>>
>> filter = LessThanFilter([10, 20, 30, 40, 50])
>> filter[25] += [15, 17, 23]
>>
>> Should that last line not raise an exception?
>
>
> In this case it will fail to catch what is probably an error,
> but you can't expect the language to find all your bugs for
> you. If you wrote the same bug this way:
>
>    filter[25].extend([15, 17, 23])
>
> it wouldn't be caught either.
>
> What's happening is that we're trying to use the syntax
> a += b to mean two different things:
>
> 1) Shorthand for a = a + b
>
> 2) A way of expressing an in-place modification, such
>    as a.extend(b)
>
> Case (2) is not really an assignment at all, so arguably
> it shouldn't require the LHS to support assignment.

In my view the second one is wrong.  a += b should be understood as
being equivalent to a = a + b, but with the *possible* and by no means
guaranteed optimization that the operation may be performed in-place.

In fact, if you read the documentation for lists, you may notice that
while they clearly cover the + operator and the extend method, they do
not explicitly document the list class's += operator.  So although I'm
not entirely sure whether it is intentional or not, and I would be
quite surprised if some implementation were actually to differ on this
point, the language does *not* from what I can see guarantee that the
+= operator on lists is equivalent to calling .extend.

That having been said, code that uses += and relies on the operation
to be performed in-place should be considered buggy.  If you need the
operation to be performed in-place, then use in-place methods like
list.extend.  If you need the operation not to be performed in-place,
then use a = a + b.  If you're ambivalent on the in-place issue and
just want to write polymorphic code, that's when you should consider
using +=.


From python at mrabarnett.plus.com  Sat Mar  8 21:42:46 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Sun, 09 Mar 2014 02:42:46 +0000
Subject: How is unicode implemented behind the scenes?
In-Reply-To: <531BD49C.4090602@mrabarnett.plus.com>
References: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>
 <531BD49C.4090602@mrabarnett.plus.com>
Message-ID: <531BD526.4040206@mrabarnett.plus.com>

On 2014-03-09 02:40, MRAB wrote:
> On 2014-03-09 02:08, Dan Stromberg wrote:
>> OK, I know that Unicode data is stored in an encoding on disk.
>>
>> But how is it stored in RAM?
>>
>> I realize I shouldn't write code that depends on any relevant
>> implementation details, but knowing some of the more common
>> implementation options would probably help build an intuition for
>> what's going on internally.
>>
>> I've heard that characters are no longer all c bytes wide internally,
>> so is it sometimes utf-8?
>>
> No.
>
>   From Python 3.3, it's an array of 1, 2 or 4 bytes per codepoint.
>
> In Python terms:
>
> if all(c <= '\xFF' for c in string):
>       use 1 byte per codepoint
> elif all(c <= '\xFFFF' for c in string):
>       use 2 bytes per codepoint
> else:
>       use 4 bytes per codepoint
>
Oops! That should, of course, be:

if all(c <= '\xFF' for c in string):
     use 1 byte per codepoint
elif all(c <= '\uFFFF' for c in string):
     use 2 bytes per codepoint
else:
     use 4 bytes per codepoint



From steve+comp.lang.python at pearwood.info  Sat Mar  8 21:50:49 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 09 Mar 2014 02:50:49 GMT
Subject: How is unicode implemented behind the scenes?
References: <mailman.7942.1394330927.18130.python-list@python.org>
Message-ID: <531bd709$0$29985$c3e8da3$5496439d@news.astraweb.com>

On Sat, 08 Mar 2014 18:08:38 -0800, Dan Stromberg wrote:

> OK, I know that Unicode data is stored in an encoding on disk.
> 
> But how is it stored in RAM?

There are various common ways to store Unicode strings in RAM.

The first, UTF-16, treats every character [aside: technically, a code 
point] as a double byte rather than a single byte. So the letter "A" is 
stored as two bytes 0x0041 (or 0x4100 depending on your platform's byte 
order). Using two bytes allows for a maximum of 65536 different 
characters, *way* too few for the whole Unicode character set, so UTF-16 
has an escaping mechanism where characters beyond ordinal 0xFFFF are 
stored as *two* "characters" (again, actually, code points) called 
surrogate pairs.

That means that a sequence of (say) four human-readable characters may, 
depending on those characters, take up anything from eight bytes to 
sixteen bytes, and you cannot tell which until you walk through the 
sequence inspecting each pair of bytes:

while there are still pairs of bytes to inspect:
    c = get_next_pair()
    if is_low_surrogate(c):
        error
    elif is_high_surrogate(c):
        d = get_next_pair()
        if not is_low_surrogate(d):
            error
        print make_char_from_surrogate_pair(c, d)
    else:
        print make_char_from_double_byte(c)

So UTF-16 is a *variable width* (could be 1 unit, could be 2 units) 
*double byte* encoding (each unit is two bytes).

Prior to Python 3.3, using UTF-16 was an option when compiling Python's 
source code. Such versions of the interpreter are called "narrow builds".

Another option is UTF-32. UTF-32 uses four bytes for every character. 
That's enough to store every Unicode character, and then some, so there 
are no surrogate pairs needed. But every character takes up four bytes: 
"A" would be stored as 0x00000041 or 0x41000000. Although UTF-32 is 
faster than UTF-16, because you don't have to walk the string checking 
each individual pair of bytes to see if they are part of a surrogate, 
strings use up to twice as much memory as UTF-16 whether they need it or 
not. (And four times more memory than ASCII strings.)

Prior to Python 3.3, UTF-32 was a build option too. Such versions of the 
interpreter are called "wide builds".

Another option is to use UTF-8 internally. With UTF-8, every character 
uses between 1 and 4 bytes. By design, ASCII characters are stored using 
a single byte, the same byte they would have in old fashioned single-byte 
ASCII: the letter "A" is stored as 0x41. (The algorithm used by UTF-8 can 
continue up to six bytes, but there is no need to since there aren't that 
many Unicode characters.) Because it's variable-width, you have the same 
variable-width issues as UTF-16, only even more so, but because most 
common characters (at least for English speakers) use only 1 or 2 bytes, 
it's much more compact than either.

No version of Python has, to my knowledge, used UTF-8 internally. Some 
other languages, such as Go and Haskell, do, and consequently string 
processing is slow for them.

In Python 3.3, CPython introduced an internal scheme that gives the best 
of all worlds. When a string is created, Python uses a different 
implementation depending on the characters in the string:

* If all the characters are ASCII or Latin-1, then the string uses 
  a single byte per character.

* If all the characters are no greater than ordinal value 0xFFFF, 
  then UTF-16 is used. Because the characters are all below 0xFFFF, 
  no surrogate pairs are required.

* Only if there is at least one ord() greater than 0xFFFF does 
  Python use UTF-32 for that string.

The end result is that creating strings is slightly slower, as Python may 
have to inspect each character at most twice to decide what system to 
use. But memory use is much improved: Python has *many* strings (every 
function, method and class uses many strings in their implementation) and 
the memory savings can be considerable. Depending on your application and 
what you do with those strings, that may even lead to time savings as 
well as memory savings.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ian.g.kelly at gmail.com  Sat Mar  8 21:55:25 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 8 Mar 2014 19:55:25 -0700
Subject: Tuples and immutability
In-Reply-To: <bo1rseFlmgoU1@mid.individual.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rseFlmgoU1@mid.individual.net>
Message-ID: <CALwzidntEerrdph0CwRDZ8RbsS+mwa1ovK-MMXqNokBPM9qp1w@mail.gmail.com>

On Sat, Mar 8, 2014 at 5:45 PM, Gregory Ewing
<greg.ewing at canterbury.ac.nz> wrote:
> Ian Kelly wrote:
>
>> I already mentioned this earlier in the thread, but a balanced binary
>> tree might implement += as node insertion and then return a different
>> object if the balancing causes the root node to change.
>
>
> That would be a really bad way to design a binary tree
> implementation. What if there is another reference to
> the tree somewhere? It's still going to be referring to
> the old root object, and will have an incoherent view
> of the data -- partly old and partly new.
>
> If you're going to have a mutable tree, it needs to be
> encapsulated in a stable top-level object.

Well, as I parenthetically noted the first time I brought it up,
"whether this is good design is tangential; it's a possible design".
The language shouldn't be written such that only those designs deemed
"good" by some external committee can be implemented.  What you
dismiss as "really bad" may be exactly what somebody else needs, and
maybe they intend that there won't be other references.


From rosuav at gmail.com  Sat Mar  8 21:56:39 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 9 Mar 2014 13:56:39 +1100
Subject: How is unicode implemented behind the scenes?
In-Reply-To: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>
References: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>
Message-ID: <CAPTjJmqQk9vp6jZJ2s43d0qwUeFw-AWrAsDGogKj7j1G5K_zVQ@mail.gmail.com>

On Sun, Mar 9, 2014 at 1:08 PM, Dan Stromberg <drsalists at gmail.com> wrote:
> OK, I know that Unicode data is stored in an encoding on disk.
>
> But how is it stored in RAM?
>
> I realize I shouldn't write code that depends on any relevant
> implementation details, but knowing some of the more common
> implementation options would probably help build an intuition for
> what's going on internally.
>
> I've heard that characters are no longer all c bytes wide internally,
> so is it sometimes utf-8?
>

As of Python 3.3, it's as MRAB described. If you like, Python chooses
between one of three (or four) encodings, based on what can handle the
string:

1) ASCII (there are some minor differences with 7-bit strings, eg it
knows the conversion to UTF-8 is the identity function)
2) Latin-1
3) UCS-2
4) UCS-4

This means that finding the Nth codepoint in a string is simply a
matter of shifting N by either 0, 0, 1, or 2, and picking the right
number of bytes from that position. You can read the gory details in
PEP 393:

http://www.python.org/dev/peps/pep-0393/

but the important bit here is the "kind", which is 01 for Latin-1, 10
for UCS-2, 11 for UCS-4. (The "ascii-only" flag is stored elsewhere.)
There's a functionally-identical field in Pike's strings, called
size_shift - 0 for ASCII or Latin-1, 1 for UCS-2, 2 for UCS-4.
Whichever it is, it's really efficient - and as an added bonus, all
those ASCII-only strings that scripts are full of (you know, words
like "print" and "len" and "int") are stored compactly, so it's much
tighter than the 3.2 builds, even narrow ones. It's pretty awesome!

ChrisA


From roy at panix.com  Sat Mar  8 22:01:59 2014
From: roy at panix.com (Roy Smith)
Date: Sat, 08 Mar 2014 22:01:59 -0500
Subject: How is unicode implemented behind the scenes?
References: <mailman.7942.1394330927.18130.python-list@python.org>
 <531bd709$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-A8220E.22015908032014@news.panix.com>

In article <531bd709$0$29985$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> There are various common ways to store Unicode strings in RAM.
> 
> The first, UTF-16.
> [...]
> Another option is UTF-32.
> [...]
> Another option is to use UTF-8 internally.
> [...]
> In Python 3.3, CPython introduced an internal scheme that gives the best 
> of all worlds. When a string is created, Python uses a different 
> implementation depending on the characters in the string:

This was an excellent post, but I would take exception to the "best of 
all worlds" statement.  I would put it a little less absolutely and say 
something like, "a good compromise for many common use cases".  I would 
even go with, "... for most common use cases".  But, there are 
situations where it loses.


From rustompmody at gmail.com  Sat Mar  8 22:12:28 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Sat, 8 Mar 2014 19:12:28 -0800 (PST)
Subject: How is unicode implemented behind the scenes?
In-Reply-To: <531bd709$0$29985$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.7942.1394330927.18130.python-list@python.org>
 <531bd709$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <fd13b137-18a0-46c1-975b-b5fc8486d94f@googlegroups.com>

On Sunday, March 9, 2014 8:20:49 AM UTC+5:30, Steven D'Aprano wrote:
> No version of Python has, to my knowledge, used UTF-8 internally. Some 
> other languages, such as Go and Haskell, do, and consequently string 
> processing is slow for them.

Haskell: Its more like: "Heres the menu, take your pick"
http://blog.ezyang.com/2010/08/strings-in-haskell/




From rosuav at gmail.com  Sat Mar  8 22:19:00 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 9 Mar 2014 14:19:00 +1100
Subject: How is unicode implemented behind the scenes?
In-Reply-To: <roy-A8220E.22015908032014@news.panix.com>
References: <mailman.7942.1394330927.18130.python-list@python.org>
 <531bd709$0$29985$c3e8da3$5496439d@news.astraweb.com>
 <roy-A8220E.22015908032014@news.panix.com>
Message-ID: <CAPTjJmow41tZgySDNsHrr50Pd8yVNdB8RprMcB6dYoZHhuvjuA@mail.gmail.com>

On Sun, Mar 9, 2014 at 2:01 PM, Roy Smith <roy at panix.com> wrote:
> In article <531bd709$0$29985$c3e8da3$5496439d at news.astraweb.com>,
>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>
>> There are various common ways to store Unicode strings in RAM.
>>
>> The first, UTF-16.
>> [...]
>> Another option is UTF-32.
>> [...]
>> Another option is to use UTF-8 internally.
>> [...]
>> In Python 3.3, CPython introduced an internal scheme that gives the best
>> of all worlds. When a string is created, Python uses a different
>> implementation depending on the characters in the string:
>
> This was an excellent post, but I would take exception to the "best of
> all worlds" statement.  I would put it a little less absolutely and say
> something like, "a good compromise for many common use cases".  I would
> even go with, "... for most common use cases".  But, there are
> situations where it loses.

It's universally good for string indexing/slicing on binary CPUs
(there's no point using a 24-bit or 21-bit representation on an
Intel-compatible CPU, even though they'd be just as good as UTC-32).
It's not a compromise, so much as a recognition that Python offers
convenient operators for indexing and slicing. If, on the other hand,
Python fundamentally worked with U+0020 separated words (REXX has a
whole set of word-based functions), then it might be better to
represent strings as lists of words internally. Or if the string
operations are primarily based on the transitions between Unicode
types of "space" and "non-space", which would be more likely these
days, then something of that sort would still work. Anyway, it's based
on the operations the language makes convenient, and which will
therefore be common and expected to be fast: those are the operations
to optimize for.

If the only thing you ever do with a string is iterate sequentially
over its characters, UTF-8 would be the perfect representation. It's
compact, you can concatenate strings without re-encoding, and it
iterates forwards easily. But it sucks for "give me character #142857
from this string", so it's a bad choice for Python.

ChrisA


From ned at nedbatchelder.com  Sat Mar  8 22:48:51 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Sat, 08 Mar 2014 22:48:51 -0500
Subject: How is unicode implemented behind the scenes?
In-Reply-To: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>
References: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>
Message-ID: <lfgoal$3a8$1@ger.gmane.org>

On 3/8/14 9:08 PM, Dan Stromberg wrote:
> OK, I know that Unicode data is stored in an encoding on disk.
>
> But how is it stored in RAM?
>
> I realize I shouldn't write code that depends on any relevant
> implementation details, but knowing some of the more common
> implementation options would probably help build an intuition for
> what's going on internally.
>
> I've heard that characters are no longer all c bytes wide internally,
> so is it sometimes utf-8?
>
> Thanks.
>

In abstract terms, a Unicode string is a sequence of integers (code 
points).  There are lots of ways to store a sequence of integers.

In Python 2.x, it's either a vector of 16-bit ints, or 32-bit ints. 
These are the Unicode representations known as UTF-16 and UTF-32, 
respectively, and which you have depends on whether you have a "narrow" 
or "wide" build of Python.  You can tell the difference by examining 
sys.maxunicode, which is 65535 (narrow) or 1114111 (wide).

In Python 3.3, the representation was changed from narrow/wide to the 
so-called Flexible String Representation which others here have 
described.  It uses either 1-, 2-, or 4-bytes per code point, depending 
on the set of code points in the string.  It's specified in PEP 393: 
http://legacy.python.org/dev/peps/pep-0393/

-- 
Ned Batchelder, http://nedbatchelder.com



From nispray at gmail.com  Sat Mar  8 22:49:10 2014
From: nispray at gmail.com (Wesley)
Date: Sat, 8 Mar 2014 19:49:10 -0800 (PST)
Subject: gdb unable to read python frame information
In-Reply-To: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
Message-ID: <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>

Anybody has suggestions?

This really makes me crazy...


From dan at tombstonezero.net  Sun Mar  9 00:46:06 2014
From: dan at tombstonezero.net (Dan Sommers)
Date: Sun, 9 Mar 2014 05:46:06 +0000 (UTC)
Subject: How is unicode implemented behind the scenes?
References: <mailman.7942.1394330927.18130.python-list@python.org>
 <531bd709$0$29985$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lfgv6t$qmf$1@dont-email.me>

On Sun, 09 Mar 2014 03:50:49 +0000, Steven D'Aprano wrote:

> ... UTF-16 ... the letter "A" is stored as two bytes 0x0041 (or 0x4100
> depending on your platform's byte order) ...

At the risk of being pedantic, the two bytes are 0x00 and 0x41, and the
order in which they appear in memory depends on your platform and even
your particular view of that platform (do stacks grow up or down?  are
addresses of higher memory larger or smaller?).

> ... UTF-32 ... "A" would be stored as 0x00000041 or 0x41000000 ...

Or even some other sequence if you're on a PDP-11.

See <http://www.catb.org/jargon/html/M/middle-endian.html>.

But you knew that.  ;-)

Pedantic'ly yours,
Dan


From tnajun at gmail.com  Sun Mar  9 03:52:58 2014
From: tnajun at gmail.com (Jun Tanaka)
Date: Sun, 9 Mar 2014 16:52:58 +0900
Subject: process.popen with Japanese args => UTF8 JAVA
Message-ID: <CACm6JvVDdnxwuV1Nz7pH1fv3n4Vt5eBnBd9se2PtcCELHHK2jg@mail.gmail.com>

Hello,

I have tried to process.popen to run java program with Japanese language.
test.java is compiled with utf8
'???' below means Japanese in Japanese.
but it does not work. Anyone who knows this matter well. Please help.

Jun

>>>>>>>>python code>>>>>>>>>>>>>
sentence = '???'
filename = 'japanese'
java_file = 'test'
cmd = "java {0} {1} {2}".format(java_file, sentence, filename)
proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE,
stderr=subprocess.STDOUT)
>>>>>>>>python code end>>>>>>>>>>>>>>>>>>>>>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-list/attachments/20140309/762b2218/attachment.html>

From ben+python at benfinney.id.au  Sun Mar  9 04:12:20 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sun, 09 Mar 2014 19:12:20 +1100
Subject: process.popen with Japanese args => UTF8 JAVA
References: <CACm6JvVDdnxwuV1Nz7pH1fv3n4Vt5eBnBd9se2PtcCELHHK2jg@mail.gmail.com>
Message-ID: <8538irx02j.fsf@benfinney.id.au>

Jun Tanaka <tnajun at gmail.com> writes:

> I have tried to process.popen to run java program with Japanese language.
> test.java is compiled with utf8
> '???' below means Japanese in Japanese.
> but it does not work.

What are you expecting to happen, and what happens instead? What error
(if any) is produced?



From wxjmfauth at gmail.com  Sun Mar  9 04:39:32 2014
From: wxjmfauth at gmail.com (wxjmfauth at gmail.com)
Date: Sun, 9 Mar 2014 00:39:32 -0800 (PST)
Subject: How is unicode implemented behind the scenes?
In-Reply-To: <mailman.7943.1394332835.18130.python-list@python.org>
References: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>
 <mailman.7943.1394332835.18130.python-list@python.org>
Message-ID: <751cbe5d-ebbe-4f4e-93a9-6012667297e3@googlegroups.com>

Le dimanche 9 mars 2014 03:40:28 UTC+1, MRAB a ?crit?:
> On 2014-03-09 02:08, Dan Stromberg wrote:
> 
> > OK, I know that Unicode data is stored in an encoding on disk.
> 
> >
> 
> > But how is it stored in RAM?
> 
> >
> 
> > I realize I shouldn't write code that depends on any relevant
> 
> > implementation details, but knowing some of the more common
> 
> > implementation options would probably help build an intuition for
> 
> > what's going on internally.
> 
> >
> 
> > I've heard that characters are no longer all c bytes wide internally,
> 
> > so is it sometimes utf-8?
> 
> >
> 
> No.
> 
> 
> 
>  From Python 3.3, it's an array of 1, 2 or 4 bytes per codepoint.
> 
> 
> 
> In Python terms:
> 
> 
> 
> if all(c <= '\xFF' for c in string):
> 
>      use 1 byte per codepoint
> 
> elif all(c <= '\xFFFF' for c in string):
> 
>      use 2 bytes per codepoint
> 
> else:
> 
>      use 4 bytes per codepoint

A very, very nice recursive mathematical
absurdity.

jmf


From cs at zip.com.au  Sun Mar  9 05:09:26 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Sun, 9 Mar 2014 20:09:26 +1100
Subject: process.popen with Japanese args => UTF8 JAVA
In-Reply-To: <CACm6JvVDdnxwuV1Nz7pH1fv3n4Vt5eBnBd9se2PtcCELHHK2jg@mail.gmail.com>
References: <CACm6JvVDdnxwuV1Nz7pH1fv3n4Vt5eBnBd9se2PtcCELHHK2jg@mail.gmail.com>
Message-ID: <20140309090926.GA16238@cskk.homeip.net>

On 09Mar2014 16:52, Jun Tanaka <tnajun at gmail.com> wrote:
> I have tried to process.popen to run java program with Japanese language.
> test.java is compiled with utf8
> '???' below means Japanese in Japanese.
> but it does not work. Anyone who knows this matter well. Please help.
> Jun
> 
> >>>>>>>>python code>>>>>>>>>>>>>
> sentence = '???'
> filename = 'japanese'
> java_file = 'test'
> cmd = "java {0} {1} {2}".format(java_file, sentence, filename)
> proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE,
> stderr=subprocess.STDOUT)
> >>>>>>>>python code end>>>>>>>>>>>>>>>>>>>>>>

Echoing Ben, what errors do you get? And what expected?

But examining your program, it is possible that any error messages
are being concealed. Details below.

Firstly, I am surprised that the sentence comes before the java
file "test". Try swapping them.

Also, if you're doing this in a UNIX system of some kind, and therefore
your "cmd" variable is actually a shell comment, turn on tracing.
Change this:

  cmd = "java {0} {1} {2}"

to this:

  cmd = "set -x; java {0} {1} {2}"

It will show you the command the shell executes.

Finally, why do you have:

  stderr=subprocess.STDOUT

Normally you would leave stderr alone, so that error messages show
on your terminal. In particular, the shell tracing an any error
messages from your java command go to stderr, and grabbing stderr
like that may well be concealing any useful error messages you ought
to be seeing. I would be inclined to simple get rid of your stderr=
parameter and see what shows up.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

Processes are like potatoes.    - NCR device driver manual


From marko at pacujo.net  Sun Mar  9 05:17:33 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 09 Mar 2014 11:17:33 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <roy-4FBE95.17224908032014@news.panix.com>
Message-ID: <874n374toy.fsf@elektro.pacujo.net>

Roy Smith <roy at panix.com>:

>  Marko Rauhamaa <marko at pacujo.net> wrote:
>
>> If I had to choose between a hash table and AVL (or RB) tree in the
>> standard library, it would definitely have to be the latter. It is more
>> generally usable, has fewer corner cases and probably has an equal
>> performance even in hash tables' sweet spot.
>
> The C++ folks made that decision, and people spent the next 10 years
> complaining, "Why is there no hash table in STL?"

Well, luckily, nobody should need to choose. Even STL has an
unordered_map now.


Marko


From marko at pacujo.net  Sun Mar  9 05:27:24 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 09 Mar 2014 11:27:24 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
Message-ID: <87zjkz3eo3.fsf@elektro.pacujo.net>

Dan Stromberg <drsalists at gmail.com>:

> On Sat, Mar 8, 2014 at 1:21 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> If I had to choose between a hash table and AVL (or RB) tree in the
>> standard library, it would definitely have to be the latter. It is more
>> generally usable, has fewer corner cases and probably has an equal
>> performance even in hash tables' sweet spot.
>
> Actually, in the performance comparison I mentioned previously, I
> compared Python dict's to a bunch of different balanced trees and one
> unbalanced tree. The dictionary was much faster, though granted, it
> was the only one in C.

Yes, that is one major detail. There must be many more.


Marko


From marko at pacujo.net  Sun Mar  9 05:35:31 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 09 Mar 2014 11:35:31 +0200
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
Message-ID: <87vbvn3eak.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> In my view the second one is wrong. a += b should be understood as
> being equivalent to a = a + b, but with the *possible* and by no means
> guaranteed optimization that the operation may be performed in-place.

Some call it an optimization, others call it a side effect.

Anyway, that's how it has been explicitly defined in the language
specification so that's the reality whether one likes it or not.


Marko


From rustompmody at gmail.com  Sun Mar  9 06:32:23 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Sun, 9 Mar 2014 03:32:23 -0700 (PDT)
Subject: How is unicode implemented behind the scenes?
In-Reply-To: <751cbe5d-ebbe-4f4e-93a9-6012667297e3@googlegroups.com>
References: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>
 <mailman.7943.1394332835.18130.python-list@python.org>
 <751cbe5d-ebbe-4f4e-93a9-6012667297e3@googlegroups.com>
Message-ID: <a47099d2-45df-46eb-8317-59409b18ec9a@googlegroups.com>

On Sunday, March 9, 2014 2:09:32 PM UTC+5:30, wxjm... at gmail.com wrote:
> Le dimanche 9 mars 2014 03:40:28 UTC+1, MRAB a ?crit?:
> > On 2014-03-09 02:08, Dan Stromberg wrote:
> > > OK, I know that Unicode data is stored in an encoding on disk.
> > > But how is it stored in RAM?
> > > I realize I shouldn't write code that depends on any relevant
> > > implementation details, but knowing some of the more common
> > > implementation options would probably help build an intuition for
> > > what's going on internally.
> > > I've heard that characters are no longer all c bytes wide internally,
> > > so is it sometimes utf-8?
> > No.
> >  From Python 3.3, it's an array of 1, 2 or 4 bytes per codepoint.
> > In Python terms:
> > if all(c <= '\xFF' for c in string):
> >      use 1 byte per codepoint
> > elif all(c <= '\xFFFF' for c in string):
> >      use 2 bytes per codepoint
> > else:
> >      use 4 bytes per codepoint

> A very, very nice recursive mathematical absurdity.

As a profoundly astute mathematician
v v n r m a
can be parsed in 42 different ways (5th catalan number)

Which parse did you intend?




From georg at python.org  Sun Mar  9 06:39:14 2014
From: georg at python.org (Georg Brandl)
Date: Sun, 09 Mar 2014 11:39:14 +0100
Subject: [RELEASED] Python 3.3.5
Message-ID: <531C44D2.9070501@python.org>

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On behalf of the Python development team, I'm very happy to announce
the release of Python 3.3.5.

Python 3.3.5 includes fixes for these important issues:

* a 3.3.4 regression in zipimport (see http://bugs.python.org/issue20621)
* a 3.3.4 regression executing scripts with a coding declared and Windows
  newlines (see http://bugs.python.org/issue20731)
* potential DOS using compression codecs in bytes.decode() (see
  http://bugs.python.org/issue19619 and http://bugs.python.org/issue20404)

and also fixes quite a few other bugs.

Python 3.3 includes a range of improvements of the 3.x series, as well
as easier porting between 2.x and 3.x.  In total, almost 500 API items
are new or improved in Python 3.3.  For a more extensive list of
changes in the 3.3 series, see

    http://docs.python.org/3.3/whatsnew/3.3.html

To download Python 3.3.5 visit:

    http://www.python.org/downloads/release/python-335/


This is a production release, please report any bugs to

     http://bugs.python.org/

The final release is scheduled one week from now.


Enjoy!

- -- 
Georg Brandl, Release Manager
georg at python.org
(on behalf of the entire python-dev team and 3.3's contributors)
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.22 (GNU/Linux)

iEYEARECAAYFAlMcRNEACgkQN9GcIYhpnLAVqACeMoOOuuNX5iP6at9zbIZDnkqK
idwAoKb2FxAJlirhs2BmdESEaQiqBDJd
=smeC
-----END PGP SIGNATURE-----


From nispray at gmail.com  Sun Mar  9 10:46:10 2014
From: nispray at gmail.com (Wesley)
Date: Sun, 9 Mar 2014 07:46:10 -0700 (PDT)
Subject: Problem using py-bt, py-locals, etc. during GDB debugging [solved]
In-Reply-To: <mailman.594.1354839735.29569.python-list@python.org>
References: <20121206213941.GA5363@mshroyer-d>
 <mailman.594.1354839735.29569.python-list@python.org>
Message-ID: <aa0b71e6-cb87-40ec-897e-8215c3176ec0@googlegroups.com>

I hit a problem alike yours.
Cannot fix according your method.

Here is snippet:
root at localhost python]# gdb python 40290
GNU gdb (GDB) 7.7
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from python...done.
Attaching to program: /usr/local/bin/python, process 40290
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
0x00000030a98e15c3 in ?? ()
(gdb) py-bt
(gdb) py-list
Unable to locate python frame
(gdb) py-locals
Unable to locate python frame
(gdb) 

I use gdb 7.7, python 2.6.6 , centos 6.5 64bit
Any suggestion?

Thanks.
Wesley


From breamoreboy at yahoo.co.uk  Sun Mar  9 10:53:05 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 09 Mar 2014 14:53:05 +0000
Subject: How is unicode implemented behind the scenes?
In-Reply-To: <a47099d2-45df-46eb-8317-59409b18ec9a@googlegroups.com>
References: <CAGGBd_rSN1bMHkQYix8Lo0TfXi3_k+Q9nu25vMokR1+Eumf5Cg@mail.gmail.com>
 <mailman.7943.1394332835.18130.python-list@python.org>
 <751cbe5d-ebbe-4f4e-93a9-6012667297e3@googlegroups.com>
 <a47099d2-45df-46eb-8317-59409b18ec9a@googlegroups.com>
Message-ID: <lfhv8e$dp2$1@ger.gmane.org>

On 09/03/2014 10:32, Rustom Mody wrote:
> On Sunday, March 9, 2014 2:09:32 PM UTC+5:30, wxjm... at gmail.com wrote:
>> Le dimanche 9 mars 2014 03:40:28 UTC+1, MRAB a ?crit :
>>> On 2014-03-09 02:08, Dan Stromberg wrote:
>>>> OK, I know that Unicode data is stored in an encoding on disk.
>>>> But how is it stored in RAM?
>>>> I realize I shouldn't write code that depends on any relevant
>>>> implementation details, but knowing some of the more common
>>>> implementation options would probably help build an intuition for
>>>> what's going on internally.
>>>> I've heard that characters are no longer all c bytes wide internally,
>>>> so is it sometimes utf-8?
>>> No.
>>>   From Python 3.3, it's an array of 1, 2 or 4 bytes per codepoint.
>>> In Python terms:
>>> if all(c <= '\xFF' for c in string):
>>>       use 1 byte per codepoint
>>> elif all(c <= '\xFFFF' for c in string):
>>>       use 2 bytes per codepoint
>>> else:
>>>       use 4 bytes per codepoint
>
>> A very, very nice recursive mathematical absurdity.
>
> As a profoundly astute mathematician
> v v n r m a
> can be parsed in 42 different ways (5th catalan number)
>
> Which parse did you intend?
>
>

Please don't feed this particular troll, it's a complete waste of time.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From breamoreboy at yahoo.co.uk  Sun Mar  9 10:57:37 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 09 Mar 2014 14:57:37 +0000
Subject: gdb unable to read python frame information
In-Reply-To: <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
Message-ID: <lfhvgu$dp2$2@ger.gmane.org>

On 09/03/2014 03:49, Wesley wrote:
> Anybody has suggestions?
>
> This really makes me crazy...
>

What makes you crazy?  You keep sending messages with no context.  We 
might be smart, but we're not (yet :) mind readers.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From varsha1901 at gmail.com  Sun Mar  9 13:56:38 2014
From: varsha1901 at gmail.com (Varsha Holla)
Date: Sun, 9 Mar 2014 10:56:38 -0700 (PDT)
Subject: image processing in python and opencv
Message-ID: <512500c5-3c2f-49c8-861f-5755991c3abb@googlegroups.com>

i have no idea how to retrieve indexed images stored in ordered dictionary, using its values like : blue,green,red mean along with contrast, energy, homogeneity and correlation. as i have calculated the euclidean distance and i don't know how to display the images which are similar.

thanks in advance


From joshua at landau.ws  Sun Mar  9 13:54:46 2014
From: joshua at landau.ws (Joshua Landau)
Date: Sun, 9 Mar 2014 17:54:46 +0000
Subject: Tuples and immutability
In-Reply-To: <CAPTjJmoCK9YT5_rNQdNqr+VXGAKUuo5Pbfhk4ouBHecHXPBc4A@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <CAPTjJmoCK9YT5_rNQdNqr+VXGAKUuo5Pbfhk4ouBHecHXPBc4A@mail.gmail.com>
Message-ID: <CAN1F8qXHi2b+2HzQWD-6PybOCf7pPgUQ93-Giw7+Rk=jTRpkMw@mail.gmail.com>

On 28 February 2014 14:43, Chris Angelico <rosuav at gmail.com> wrote:
> On Sat, Mar 1, 2014 at 1:41 AM, Joshua Landau <joshua at landau.ws> wrote:
>> Would it be better to add a check here, such that if this gets raised
>> to the top-level it includes a warning ("Addition was inplace;
>> variable probably mutated despite assignment failure")?
>
> That'd require figuring out whether or not the variable was actually
> mutated, and that's pretty hard to work out.

It does not. First, the "warning" is actually an attachment to the
exception so is only shown if the exception is uncaught. This should
basically never happen in working code. The warning exists only to
remove likely misunderstanding in these odd cases.

Even if "x = (1,); x[0] += 1" warned "addition was inplace; possible
mutation occurred" or whatever phrasing you wish, this would only
cause a quick check of the results.


From rosuav at gmail.com  Sun Mar  9 14:13:24 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 10 Mar 2014 05:13:24 +1100
Subject: Tuples and immutability
In-Reply-To: <CAN1F8qXHi2b+2HzQWD-6PybOCf7pPgUQ93-Giw7+Rk=jTRpkMw@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <CAPTjJmoCK9YT5_rNQdNqr+VXGAKUuo5Pbfhk4ouBHecHXPBc4A@mail.gmail.com>
 <CAN1F8qXHi2b+2HzQWD-6PybOCf7pPgUQ93-Giw7+Rk=jTRpkMw@mail.gmail.com>
Message-ID: <CAPTjJmr=eyUb6BxUYC0y8qY75_qeCEYAmnJzM0B_6o20RW+S+Q@mail.gmail.com>

On Mon, Mar 10, 2014 at 4:54 AM, Joshua Landau <joshua at landau.ws> wrote:
> On 28 February 2014 14:43, Chris Angelico <rosuav at gmail.com> wrote:
>> On Sat, Mar 1, 2014 at 1:41 AM, Joshua Landau <joshua at landau.ws> wrote:
>>> Would it be better to add a check here, such that if this gets raised
>>> to the top-level it includes a warning ("Addition was inplace;
>>> variable probably mutated despite assignment failure")?
>>
>> That'd require figuring out whether or not the variable was actually
>> mutated, and that's pretty hard to work out.
>
> It does not. First, the "warning" is actually an attachment to the
> exception so is only shown if the exception is uncaught. This should
> basically never happen in working code. The warning exists only to
> remove likely misunderstanding in these odd cases.
>
> Even if "x = (1,); x[0] += 1" warned "addition was inplace; possible
> mutation occurred" or whatever phrasing you wish, this would only
> cause a quick check of the results.

I think I see what you're saying here. But ignore "top-level"; this
should just be a part of the exception message, no matter what.
Otherwise things that recreate the REPL (like IDLE) or that isolate
two sections of the code (like a web server framework) wouldn't get
the benefit, because the exception's not caught at the true top-level.

>>> x=1,
>>> x[0]+=0
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    x[0]+=0
TypeError: 'tuple' object does not support item assignment

What you're saying is that this should notice that it's doing an
augmented assignment and give some more text. This can be done; all
you need to do is catch the error and reraise it with more info:

>>> try:
    x[0]+=0
except TypeError as e:
    if 'does not support item assignment' in e.args[0]:
        raise TypeError(e.args[0]+"\nAugmented assignment used;
mutation may have occurred.") from None
    raise

Traceback (most recent call last):
  File "<pyshell#16>", line 5, in <module>
    raise TypeError(e.args[0]+"\nAugmented assignment used; mutation
may have occurred.") from None
TypeError: 'tuple' object does not support item assignment
Augmented assignment used; mutation may have occurred.

Now you can look at writing an import hook that does an AST transform,
locating every instance of item assignment and wrapping it like that.
It's certainly possible. I'm not sure how much benefit you'd get, but
it could be done.

ChrisA


From tjreedy at udel.edu  Sun Mar  9 14:37:27 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 09 Mar 2014 14:37:27 -0400
Subject: gdb unable to read python frame information
In-Reply-To: <lfhvgu$dp2$2@ger.gmane.org>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <lfhvgu$dp2$2@ger.gmane.org>
Message-ID: <lficd8$s0b$1@ger.gmane.org>

On 3/9/2014 10:57 AM, Mark Lawrence wrote:
> On 09/03/2014 03:49, Wesley wrote:
>> Anybody has suggestions?

Don't expect crazy things.
Send suggestions to the right place (a gdb list for a gdb enhancement).

>> This really makes me crazy...

> What makes you crazy?

The supposed fact that GnuDeBug does not understand Python frames on the 
stack.

 > You keep sending messages with no context.  We
> might be smart, but we're not (yet :) mind readers.

But we do speculate ;-)

-- 
Terry Jan Reedy



From tjreedy at udel.edu  Sun Mar  9 14:50:10 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 09 Mar 2014 14:50:10 -0400
Subject: Problem using py-bt, py-locals, etc. during GDB debugging [solved]
In-Reply-To: <aa0b71e6-cb87-40ec-897e-8215c3176ec0@googlegroups.com>
References: <20121206213941.GA5363@mshroyer-d>
 <mailman.594.1354839735.29569.python-list@python.org>
 <aa0b71e6-cb87-40ec-897e-8215c3176ec0@googlegroups.com>
Message-ID: <lfid52$493$1@ger.gmane.org>

On 3/9/2014 10:46 AM, Wesley wrote:
> I hit a problem alike yours.
> Cannot fix according your method.
>
> Here is snippet:
> root at localhost python]# gdb python 40290
> GNU gdb (GDB) 7.7

> Copyright (C) 2014 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-unknown-linux-gnu".
> Type "show configuration" for configuration details.
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>.
> Find the GDB manual and other documentation resources online at:
> <http://www.gnu.org/software/gdb/documentation/>.
> For help, type "help".
> Type "apropos word" to search for commands related to "word"...
> Reading symbols from python...done.
> Attaching to program: /usr/local/bin/python, process 40290
> Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
> Loaded symbols for /lib64/ld-linux-x86-64.so.2
> 0x00000030a98e15c3 in ?? ()

If you want people to attend to your posts and help, don't post line 
after line of irrelevant boilderplate.

> (gdb) py-bt
> (gdb) py-list
> Unable to locate python frame
> (gdb) py-locals
> Unable to locate python frame
> (gdb)
>
> I use gdb 7.7, python 2.6.6 , centos 6.5 64bit
> Any suggestion?

See above.

-- 
Terry Jan Reedy



From gherron at digipen.edu  Sun Mar  9 15:09:25 2014
From: gherron at digipen.edu (Gary Herron)
Date: Sun, 09 Mar 2014 12:09:25 -0700
Subject: image processing in python and opencv
In-Reply-To: <512500c5-3c2f-49c8-861f-5755991c3abb@googlegroups.com>
References: <512500c5-3c2f-49c8-861f-5755991c3abb@googlegroups.com>
Message-ID: <531CBC65.7030700@digipen.edu>

On 03/09/2014 10:56 AM, Varsha Holla wrote:
> i have no idea how to retrieve indexed images stored in ordered dictionary, using its values like : blue,green,red mean along with contrast, energy, homogeneity and correlation. as i have calculated the euclidean distance and i don't know how to display the images which are similar.
>
> thanks in advance

Sorry,  but is there a question here?  And is it Python related? (This 
is a Python list, right?)

And while you're rewording this as a Python related question, please 
take the time to state the problem clearly.  You'll get more help if you 
take the time to tell us what you are doing.  For instance:  You have a 
dictionary.  How was it created?  What values are stored in it?  What 
keys were used?   Why is it an "ordered" dictionary?  Is your trouble 
retrieving images, computing keys for similar images, or displaying 
images?  (All three seem to be implied above.)

Gary Herron




From joshua at landau.ws  Sun Mar  9 15:57:48 2014
From: joshua at landau.ws (Joshua Landau)
Date: Sun, 9 Mar 2014 19:57:48 +0000
Subject: Tuples and immutability
In-Reply-To: <CAPTjJmr=eyUb6BxUYC0y8qY75_qeCEYAmnJzM0B_6o20RW+S+Q@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <CAPTjJmoCK9YT5_rNQdNqr+VXGAKUuo5Pbfhk4ouBHecHXPBc4A@mail.gmail.com>
 <CAN1F8qXHi2b+2HzQWD-6PybOCf7pPgUQ93-Giw7+Rk=jTRpkMw@mail.gmail.com>
 <CAPTjJmr=eyUb6BxUYC0y8qY75_qeCEYAmnJzM0B_6o20RW+S+Q@mail.gmail.com>
Message-ID: <CAN1F8qVaeyOmbOr0FYN75hYnLBZY7crC+d0HB97jXKjSi7ALqg@mail.gmail.com>

On 9 March 2014 18:13, Chris Angelico <rosuav at gmail.com> wrote:
> I think I see what you're saying here. But ignore "top-level"; this
> should just be a part of the exception message, no matter what.

I don't think I was clear, but yes. That.

> What you're saying is that this should notice that it's doing an
> augmented assignment and give some more text. This can be done; all
> you need to do is catch the error and reraise it with more info:
> [...]
> Now you can look at writing an import hook that does an AST transform,
> locating every instance of item assignment and wrapping it like that.
> It's certainly possible. I'm not sure how much benefit you'd get, but
> it could be done.

I would probably implement it closer to home. Inside
tuple.__getitem__, there would be something like

    if context_is_augmented_assignment():
        raise TypeError(message+warning)
    else:
        raise TypeError(message)

which would have much lower technical costs. It does depend on how
costly "context_is_augmented_assignment" is, though. A speed argument
is totally valid, but I'd hope it's possible to work around.


From rosuav at gmail.com  Sun Mar  9 16:06:37 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 10 Mar 2014 07:06:37 +1100
Subject: Tuples and immutability
In-Reply-To: <CAN1F8qVaeyOmbOr0FYN75hYnLBZY7crC+d0HB97jXKjSi7ALqg@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <CAPTjJmoCK9YT5_rNQdNqr+VXGAKUuo5Pbfhk4ouBHecHXPBc4A@mail.gmail.com>
 <CAN1F8qXHi2b+2HzQWD-6PybOCf7pPgUQ93-Giw7+Rk=jTRpkMw@mail.gmail.com>
 <CAPTjJmr=eyUb6BxUYC0y8qY75_qeCEYAmnJzM0B_6o20RW+S+Q@mail.gmail.com>
 <CAN1F8qVaeyOmbOr0FYN75hYnLBZY7crC+d0HB97jXKjSi7ALqg@mail.gmail.com>
Message-ID: <CAPTjJmp5m+1X6P0WzpWhdPCbD+rxF1TQr5yd-0YBPi504c9Xjg@mail.gmail.com>

On Mon, Mar 10, 2014 at 6:57 AM, Joshua Landau <joshua at landau.ws> wrote:
> I would probably implement it closer to home. Inside
> tuple.__getitem__, there would be something like
>
>     if context_is_augmented_assignment():
>         raise TypeError(message+warning)
>     else:
>         raise TypeError(message)
>
> which would have much lower technical costs. It does depend on how
> costly "context_is_augmented_assignment" is, though. A speed argument
> is totally valid, but I'd hope it's possible to work around.

Yeah, I'm not sure there's an easy way to tell the tuple that it's an
augmented assignment. You might be able to look at the backtrace, but
that's tricky.

In theory, you could catch TypeError after any augmented assignment,
and check several things:
1) The target object does not have __setitem__
2) The object being manipulated does have __iadd__ (or corresponding for others)
3) The error is that item assignment is not possible

and if all three are the case, then add a tag to the message. But this
is best done by catching the exception. Otherwise you'd be limiting
this to tuples and lists; not to mention that this is really only an
issue of error reporting, and correct code shouldn't be tripping this
at all. So put a check like that at the place where you display the
error, if you can. The AST transform that I described would also work.

But I really think it's not worth the effort. If you get this error,
understand that it may have consequences.

ChrisA


From drsalists at gmail.com  Sun Mar  9 17:20:11 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Sun, 9 Mar 2014 14:20:11 -0700
Subject: Balanced trees
In-Reply-To: <87zjkz3eo3.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
Message-ID: <CAGGBd_ou09RDPFm9T4-dDR0Nwsng0T9oPNBRoGs_mSuM84S4CQ@mail.gmail.com>

On Sun, Mar 9, 2014 at 1:27 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Dan Stromberg <drsalists at gmail.com>:
>
>> On Sat, Mar 8, 2014 at 1:21 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> If I had to choose between a hash table and AVL (or RB) tree in the
>>> standard library, it would definitely have to be the latter. It is more
>>> generally usable, has fewer corner cases and probably has an equal
>>> performance even in hash tables' sweet spot.
>>
>> Actually, in the performance comparison I mentioned previously, I
>> compared Python dict's to a bunch of different balanced trees and one
>> unbalanced tree. The dictionary was much faster, though granted, it
>> was the only one in C.
>
> Yes, that is one major detail. There must be many more.

This is not just a detail: O(1) tends to be beat O(logn) pretty easily
for large n.


From marko at pacujo.net  Sun Mar  9 17:32:54 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 09 Mar 2014 23:32:54 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
Message-ID: <87a9czrrax.fsf@elektro.pacujo.net>

Dan Stromberg <drsalists at gmail.com>:

> This is not just a detail: O(1) tends to be beat O(logn) pretty easily
> for large n.

There is no O(1) hash table.


Marko


From ml at fam-goebel.de  Sun Mar  9 17:29:43 2014
From: ml at fam-goebel.de (Ulrich Goebel)
Date: Sun, 09 Mar 2014 22:29:43 +0100
Subject: Making Labels from python
Message-ID: <531CDD47.8020304@fam-goebel.de>

Hallo,

has anybody an idea how to make small formated documents redy to print 
with python?

I would like to print address labels as

    firstname lastname
    street and number
    cip and city

The best should be to form a PDF and send it to the label printer. So 
the PDF could be given the pagesize (labelsize) and a minimum format 
(boldface). But may be there is another light-weight-format besides PDF?

Any idea?

Ulrich


-- 
Ulrich Goebel
Paracelsusstr. 120, 53177 Bonn


From drsalists at gmail.com  Sun Mar  9 17:37:39 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Sun, 9 Mar 2014 14:37:39 -0700
Subject: Balanced trees
In-Reply-To: <87a9czrrax.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
Message-ID: <CAGGBd_rHbn9FYJM7kXn+KeEU8+zBBfhbT+gHK5LFc+3XO-XQfg@mail.gmail.com>

On Sun, Mar 9, 2014 at 2:32 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Dan Stromberg <drsalists at gmail.com>:
>
>> This is not just a detail: O(1) tends to be beat O(logn) pretty easily
>> for large n.
>
> There is no O(1) hash table.

http://stackoverflow.com/questions/2771368/can-hash-tables-really-be-o1


From marko at pacujo.net  Sun Mar  9 17:43:55 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 09 Mar 2014 23:43:55 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <mailman.7965.1394401067.18130.python-list@python.org>
Message-ID: <8761nnrqsk.fsf@elektro.pacujo.net>

Dan Stromberg <drsalists at gmail.com>:

> On Sun, Mar 9, 2014 at 2:32 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> There is no O(1) hash table.
>
> http://stackoverflow.com/questions/2771368/can-hash-tables-really-be-o1

Please elaborate.


Marko


From greg.ewing at canterbury.ac.nz  Sun Mar  9 18:03:59 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Mon, 10 Mar 2014 11:03:59 +1300
Subject: Tuples and immutability
In-Reply-To: <mailman.7944.1394332838.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
Message-ID: <bo46qcF6dofU1@mid.individual.net>

Ian Kelly wrote:
> In my view the second one is wrong.  a += b should be understood as
> being equivalent to a = a + b, but with the *possible* and by no means
> guaranteed optimization that the operation may be performed in-place.

This interpretation is at odds with the Language Reference,
section 6.2.1, Augmented Assignment Statements:

"An augmented assignment expression like x += 1 can be rewritten as x = x + 1 to
achieve a similar, but not exactly equal effect... when possible, the actual 
operation is performed
in-place, meaning that rather than creating a new object and assigning that to
the target, the old object is modified instead."

Note that it says "when possible", not "if the implementation
feels like it".

> In fact, if you read the documentation for lists, you may notice that
> while they clearly cover the + operator and the extend method, they do
> not explicitly document the list class's += operator.

The "when possible" clause, together with the fact that lists
are mutable, implies that it *will* be done in-place. There
is no need to document all the in-place operators explicitly
for every type.

-- 
Greg


From gary.herron at islandtraining.com  Sun Mar  9 18:01:11 2014
From: gary.herron at islandtraining.com (Gary Herron)
Date: Sun, 09 Mar 2014 15:01:11 -0700
Subject: Making Labels from python
In-Reply-To: <531CDD47.8020304@fam-goebel.de>
References: <531CDD47.8020304@fam-goebel.de>
Message-ID: <531CE4A7.9060203@islandtraining.com>

On 03/09/2014 02:29 PM, Ulrich Goebel wrote:
> Hallo,
>
> has anybody an idea how to make small formated documents redy to print 
> with python?
>
> I would like to print address labels as
>
>    firstname lastname
>    street and number
>    cip and city
>
> The best should be to form a PDF and send it to the label printer. So 
> the PDF could be given the pagesize (labelsize) and a minimum format 
> (boldface). But may be there is another light-weight-format besides PDF?
>
> Any idea?
>
> Ulrich
>
>

The usual python library for generating PDFs is reportlab.  It has some  
formating capabilities that my be useful for you.

Gary Herron



From drsalists at gmail.com  Sun Mar  9 18:08:20 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Sun, 9 Mar 2014 15:08:20 -0700
Subject: Balanced trees
In-Reply-To: <8761nnrqsk.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <mailman.7965.1394401067.18130.python-list@python.org>
 <8761nnrqsk.fsf@elektro.pacujo.net>
Message-ID: <CAGGBd_oSgZgtsg52JBDhSUxuxHpi9ZJSw4WfOwGwy7Zo6zhTTQ@mail.gmail.com>

On Sun, Mar 9, 2014 at 2:43 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Dan Stromberg <drsalists at gmail.com>:
>
>> On Sun, Mar 9, 2014 at 2:32 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> There is no O(1) hash table.
>>
>> http://stackoverflow.com/questions/2771368/can-hash-tables-really-be-o1
>
> Please elaborate.

A hash table of fixed size is O(1) until you fill it so full that you
start getting enough collisions to make it O(n), as one bucket becomes
a linked list.  This is because the hash function is O(1), and looking
up a value in a C array is O(1).

A more flexible hash table will not have a fixed size; instead it will
grow itself as needed.  This growth operation tends to be O(n), but
happens vanishingly infrequently as the table grows, so it's still
amortized O(1).


From ben+python at benfinney.id.au  Sun Mar  9 18:21:23 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 10 Mar 2014 09:21:23 +1100
Subject: Making Labels from python
References: <531CDD47.8020304@fam-goebel.de>
Message-ID: <85lhwjui70.fsf@benfinney.id.au>

Ulrich Goebel <ml at fam-goebel.de> writes:

> has anybody an idea how to make small formated documents redy to print
> with python?

The most reliable ?ready to print? document formats are:

* plain text
* PDF

All others, AFAIK, are significantly less reliable for that purpose.

The ?ReportLab PDF library? is a comprehensive library for this
<URL:https://pypi.python.org/pypi/reportlab/> for general page layout
and PDF generation.

-- 
 \       ?The optimist thinks this is the best of all possible worlds. |
  `\           The pessimist fears it is true.? ?J. Robert Oppenheimer |
_o__)                                                                  |
Ben Finney



From marko at pacujo.net  Sun Mar  9 18:24:01 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 10 Mar 2014 00:24:01 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <mailman.7965.1394401067.18130.python-list@python.org>
 <8761nnrqsk.fsf@elektro.pacujo.net>
 <mailman.7967.1394402908.18130.python-list@python.org>
Message-ID: <87zjkzqada.fsf@elektro.pacujo.net>

Dan Stromberg <drsalists at gmail.com>:

> On Sun, Mar 9, 2014 at 2:43 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>>> There is no O(1) hash table.
> [...]
>
> it's still amortized O(1).

So we are in perfect agreement.

Hash tables are a useful family of techniques but involve quite a bit of
cost/benefit heuristics. You can only claim O(1) if your hash table is
at least as large as the number of elements.

As for comparing them with balanced trees, I think one of the main
advantages hash tables have is better CPU cache performance. A tree
involves much more jumping around the RAM than a hash table.

Still, trees have many things going for them:

 * no need to find a good hashing function

 * no need to spend time on calculating the hash value

 * no need to find optimal hash table sizes -- no costly resizing

And of course, the main point:

 * trees are ordered

Note that most key comparisons tend to be very quick as you don't need
to traverse the whole key to locate the element. Also, it is hard to say
if going O(log n) levels deep in the tree is slower than calculating the
hash value, although, as I said, the latter operation tends to benefit
from a cache locality.

Trees are also crucial when you don't have exact matches, but for
example, when you are looking for prefix or wild-card matches.


Marko


From irmen.NOSPAM at xs4all.nl  Sun Mar  9 18:27:16 2014
From: irmen.NOSPAM at xs4all.nl (Irmen de Jong)
Date: Sun, 09 Mar 2014 23:27:16 +0100
Subject: Making Labels from python
In-Reply-To: <mailman.7964.1394400959.18130.python-list@python.org>
References: <mailman.7964.1394400959.18130.python-list@python.org>
Message-ID: <531ceac3$0$2867$e4fe514c@news.xs4all.nl>

On 9-3-2014 22:29, Ulrich Goebel wrote:
> Hallo,
> 
> has anybody an idea how to make small formated documents redy to print with python?
> 
> I would like to print address labels as
> 
>    firstname lastname
>    street and number
>    cip and city
> 
> The best should be to form a PDF and send it to the label printer. So the PDF could be
> given the pagesize (labelsize) and a minimum format (boldface). But may be there is
> another light-weight-format besides PDF?
> 
> Any idea?
> 
> Ulrich
> 
> 


If generating PDF is too heavy for your liking, you could generate some simple HTML
instead and use appropriate CSS (page-break etc) to make it suitable for correct
printing (which you can do from your web browser). I've used this technique rather
successfully myself and generating the HTML for address labels should be fairly trivial.
Getting the css right can be a bit of trial and error depending on the browser you're using.


Irmen



From marko at pacujo.net  Sun Mar  9 18:31:33 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 10 Mar 2014 00:31:33 +0200
Subject: Making Labels from python
References: <531CDD47.8020304@fam-goebel.de>
 <mailman.7968.1394403697.18130.python-list@python.org>
Message-ID: <87vbvnqa0q.fsf@elektro.pacujo.net>

Ben Finney <ben+python at benfinney.id.au>:

> The most reliable ?ready to print? document formats are:
>
> * plain text
> * PDF

You might also consider PostScript. It can be emitted from any
programming language without any special support (and any special
support would probably only get in the way).

A possibility is also the xlwt module, which allows you to generate
Excel documents. I have used to great success, but the results may not
be ready to print.


Marko


From tjreedy at udel.edu  Sun Mar  9 18:53:41 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 09 Mar 2014 18:53:41 -0400
Subject: Making Labels from python
In-Reply-To: <531CDD47.8020304@fam-goebel.de>
References: <531CDD47.8020304@fam-goebel.de>
Message-ID: <lfirdm$lg9$1@ger.gmane.org>

On 3/9/2014 5:29 PM, Ulrich Goebel wrote:
> Hallo,
>
> has anybody an idea how to make small formated documents redy to print
> with python?
>
> I would like to print address labels as
>
>     firstname lastname
>     street and number
>     cip and city
>
> The best should be to form a PDF and send it to the label printer. So
> the PDF could be given the pagesize (labelsize) and a minimum format
> (boldface). But may be there is another light-weight-format besides PDF?
>
> Any idea?

Get a label printing program that you can call from python with 
subprocess. Or look at the following
https://pypi.python.org/pypi?%3Aaction=search&term=label+printing&submit=search

The top hit is pylabels, which uses ReportLab.

-- 
Terry Jan Reedy



From ml at fam-goebel.de  Sun Mar  9 19:00:38 2014
From: ml at fam-goebel.de (Ulrich Goebel)
Date: Mon, 10 Mar 2014 00:00:38 +0100
Subject: Making Labels from python
In-Reply-To: <531CDD47.8020304@fam-goebel.de>
References: <531CDD47.8020304@fam-goebel.de>
Message-ID: <531CF296.1060700@fam-goebel.de>

Many thanks for the moment. I will try reportlab the next days.


Am 09.03.2014 22:29, schrieb Ulrich Goebel:
> Hallo,
>
> has anybody an idea how to make small formated documents redy to print
> with python?
>
> I would like to print address labels as
>
>     firstname lastname
>     street and number
>     cip and city
>
> The best should be to form a PDF and send it to the label printer. So
> the PDF could be given the pagesize (labelsize) and a minimum format
> (boldface). But may be there is another light-weight-format besides PDF?
>
> Any idea?
>
> Ulrich
>
>

-- 
Ulrich Goebel
Paracelsusstr. 120, 53177 Bonn


From tjreedy at udel.edu  Sun Mar  9 19:00:16 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 09 Mar 2014 19:00:16 -0400
Subject: Tuples and immutability
In-Reply-To: <bo46qcF6dofU1@mid.individual.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
Message-ID: <lfirq1$ouc$1@ger.gmane.org>

On 3/9/2014 6:03 PM, Gregory Ewing wrote:
> Ian Kelly wrote:
>> In my view the second one is wrong.  a += b should be understood as
>> being equivalent to a = a + b, but with the *possible* and by no means
>> guaranteed optimization that the operation may be performed in-place.
>
> This interpretation is at odds with the Language Reference,
> section 6.2.1, Augmented Assignment Statements:
>
> "An augmented assignment expression like x += 1 can be rewritten as x =
> x + 1 to
> achieve a similar, but not exactly equal effect... when possible, the
> actual operation is performed
> in-place, meaning that rather than creating a new object and assigning
> that to
> the target, the old object is modified instead."
>
> Note that it says "when possible", not "if the implementation
> feels like it".
>
>> In fact, if you read the documentation for lists, you may notice that
>> while they clearly cover the + operator and the extend method, they do
>> not explicitly document the list class's += operator.
>
> The "when possible" clause, together with the fact that lists
> are mutable, implies that it *will* be done in-place. There
> is no need to document all the in-place operators explicitly
> for every type.

The discussion of .__iop__ in the datamodel chapter was just revised 
slightly.
http://bugs.python.org/issue19953

-- 
Terry Jan Reedy



From martin.schoon at gmail.com  Sun Mar  9 19:22:25 2014
From: martin.schoon at gmail.com (Martin =?UTF-8?Q?Sch=C3=B6=C3=B6n?=)
Date: 9 Mar 2014 23:22:25 GMT
Subject: better and user friendly IDE recommended?
References: <091bbe36-8cf9-412f-b7e9-2b3cc89dd363@googlegroups.com>
 <da303c22-464f-4b01-96ec-a79be95bff48@googlegroups.com>
 <bm4rlhFl3i0U1@mid.individual.net>
 <7eab4785-4db6-416f-9bc2-56470ab9d7db@googlegroups.com>
 <bm7ghfF7nodU1@mid.individual.net>
Message-ID: <bo4bdhF6retU1@mid.individual.net>

Den 2014-02-14 skrev Martin Sch??n <martin.schoon at gmail.com>:
> Den 2014-02-14 skrev Rustom Mody <rustompmody at gmail.com>:
>> On Friday, February 14, 2014 2:57:13 AM UTC+5:30, Martin Sch??n wrote:
>>> Den 2013-09-17 skrev rusi 
>>> > On Wednesday, September 11, 2013 7:44:04 PM UTC+5:30, 
>>> > mnishpsyched wrote:
>>> > Just saw this
>>> > http://www.youtube.com/watch?v=1-dUkyn_fZA
>>> > Yeah... scientific programming and web programming are hardly the same :-)
>>> > Still it might be worth 20 minutes of your time
>>
>>> I have started testing this. It is early days so too early to pass
>>> judgement.
>>
>>> Anyone out there using Emacs + Python + Orgmode like this?
>>> I might to need ask some questions :-)
>>
>> The speaker -- Kitchin -- is quite active on the org mode list.
>> And a bunch of other babel users. You should try there.
>> And please do report back your findings!
>
> OK, I will dive into the Orgmode pond and I will report back but
> please be patient. This is a pure spare time activity.
>
Here is a first 'report' on this.

First some background on me. My formal programming training dates
back to 1980 and covered Fortran 77 on an IBM mainframe computer.
Later some Pascal and Rocky Mountain Basic was added. I wrote much
of my PhD thesis using vi and LaTeX. Post PhD I used Matlab some
and got exposed to Emacs. I am clearly not a programmer and use
code I write myself very occasionally for supporting my work. I
started to learn Python for fun but have found it useful. All modern
stuff like test drive design, IDEs, object oriented programming
etc are new to me. So now you know why I get things wrong below :-)

Until now I have only used Org-mode in an attempt to organize myself.
I have picked up some neat ideas from Bernt Hansen:
http://doc.norang.ca/org-mode.html
Still my use is very primitive.

Then I came across this thread and the abovementioned talk...

The Orgmode mailing list is a busy place and it seems to me
everyone is very advanced, trying to do things I have problems
fathoming and coding elisp and all. So, I have been lurking and
picking up some ideas on what is possible and I have been
checking them out in the manual and by testing.

My experience of combining Emacs, Orgmode and Python (and
LaTeX) is that it forms a pretty neat system for creating
documented programs, code-enhanced documents and for 
Literate programming. Exporting to PDF and 'tangling' code
seems to work as advertised (so far problems have been my
creations). You can have code with or without row numbers.
You can hide code if you only want to show the results in
your exported document.

What you don't get as far as I can see is code completion,
syntax highlighting etc since Emacs is doing this with
respect to Orgmode and not the programming language you
use.

The following two papers have been helpful/inspiring:

"Acive Documets with Org-mode" by Eric Schulte and 
Dan Davison, Computing in Science & Engineering,
May/June 2011.

"A Multi-Language Computing Environment for Literate
Programming and Reproducible Research" by Eric Schulte,
Dan Davison, Thomas Dye and Carsten Dominik, Journal
of Statistical Software, January 2012, vol. 46, Issue 3.

/Martin


From ian.g.kelly at gmail.com  Sun Mar  9 19:42:42 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 9 Mar 2014 17:42:42 -0600
Subject: Tuples and immutability
In-Reply-To: <bo46qcF6dofU1@mid.individual.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
Message-ID: <CALwzid=YjOSdy2Jjbg2eMNqj_akhN06j3yAZF0i8bTmrqcoxDQ@mail.gmail.com>

On Sun, Mar 9, 2014 at 4:03 PM, Gregory Ewing
<greg.ewing at canterbury.ac.nz> wrote:
> Ian Kelly wrote:
>>
>> In my view the second one is wrong.  a += b should be understood as
>> being equivalent to a = a + b, but with the *possible* and by no means
>> guaranteed optimization that the operation may be performed in-place.
>
>
> This interpretation is at odds with the Language Reference,
> section 6.2.1, Augmented Assignment Statements:
>
> "An augmented assignment expression like x += 1 can be rewritten as x = x +
> 1 to
> achieve a similar, but not exactly equal effect... when possible, the actual
> operation is performed
>
> in-place, meaning that rather than creating a new object and assigning that
> to
> the target, the old object is modified instead."
>
> Note that it says "when possible", not "if the implementation
> feels like it".

That's quite vague, and not much stronger a guarantee than "maybe".
It's technically "possible" for this augmented assignment to be
performed in place:

x = 12
x += 4

But it's not done in-place, because ints are meant to be immutable.
In any case, this means that whether the operation is actually
performed in-place is an implementation detail -- if not of the Python
implementation then at least of the class -- and not something the
user should take for granted.


From michael.weylandt at gmail.com  Sun Mar  9 20:01:07 2014
From: michael.weylandt at gmail.com (Michael Weylandt)
Date: Sun, 9 Mar 2014 20:01:07 -0400
Subject: better and user friendly IDE recommended?
In-Reply-To: <42BCDF72-1182-4BD9-8117-DADE21BB55DE@gmail.com>
References: <091bbe36-8cf9-412f-b7e9-2b3cc89dd363@googlegroups.com>
 <da303c22-464f-4b01-96ec-a79be95bff48@googlegroups.com>
 <bm4rlhFl3i0U1@mid.individual.net>
 <7eab4785-4db6-416f-9bc2-56470ab9d7db@googlegroups.com>
 <bm7ghfF7nodU1@mid.individual.net> <bo4bdhF6retU1@mid.individual.net>
 <42BCDF72-1182-4BD9-8117-DADE21BB55DE@gmail.com>
Message-ID: <B460CD6A-1AD6-4C2B-864A-055BACFF261E@gmail.com>



On Mar 9, 2014, at 19:58, Michael Weylandt <michael.weylandt at gmail.com> wrote:

> On Mar 9, 2014, at 19:22, Martin Sch??n <martin.schoon at gmail.com> wrote:
>> What you don't get as far as I can see is code completion,
>> syntax highlighting etc since Emacs is doing this with
>> respect to Orgmode and not the programming language you
>> use.
> 
> Put 
> 
> (setq org-src-fontify-natively t)
> 
> In your ~/.emacs or ~/.emacs.d/init.el file for syntax highlighting. 
> 
> To get the 'regular' code editing, move point into a BEGIN_SRC block and type "C-c ' " (Control-C followed by single quote). That will give you your normal python setup in a sub-buffer. Getting Python autocompletion in Emacs is a bit tricky, but there are many options. 

For Python, you'll also want

(setq org-src-preserve-indentation t)

From michael.weylandt at gmail.com  Sun Mar  9 19:58:32 2014
From: michael.weylandt at gmail.com (Michael Weylandt)
Date: Sun, 9 Mar 2014 19:58:32 -0400
Subject: better and user friendly IDE recommended?
In-Reply-To: <bo4bdhF6retU1@mid.individual.net>
References: <091bbe36-8cf9-412f-b7e9-2b3cc89dd363@googlegroups.com>
 <da303c22-464f-4b01-96ec-a79be95bff48@googlegroups.com>
 <bm4rlhFl3i0U1@mid.individual.net>
 <7eab4785-4db6-416f-9bc2-56470ab9d7db@googlegroups.com>
 <bm7ghfF7nodU1@mid.individual.net> <bo4bdhF6retU1@mid.individual.net>
Message-ID: <42BCDF72-1182-4BD9-8117-DADE21BB55DE@gmail.com>

On Mar 9, 2014, at 19:22, Martin Sch??n <martin.schoon at gmail.com> wrote:
> What you don't get as far as I can see is code completion,
> syntax highlighting etc since Emacs is doing this with
> respect to Orgmode and not the programming language you
> use.

Put 

(setq org-src-fontify-natively t)

In your ~/.emacs or ~/.emacs.d/init.el file for syntax highlighting. 

To get the 'regular' code editing, move point into a BEGIN_SRC block and type "C-c ' " (Control-C followed by single quote). That will give you your normal python setup in a sub-buffer. Getting Python autocompletion in Emacs is a bit tricky, but there are many options. 

Michael

From ian.g.kelly at gmail.com  Sun Mar  9 20:04:46 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 9 Mar 2014 18:04:46 -0600
Subject: Balanced trees
In-Reply-To: <CAGGBd_oSgZgtsg52JBDhSUxuxHpi9ZJSw4WfOwGwy7Zo6zhTTQ@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <mailman.7965.1394401067.18130.python-list@python.org>
 <8761nnrqsk.fsf@elektro.pacujo.net>
 <CAGGBd_oSgZgtsg52JBDhSUxuxHpi9ZJSw4WfOwGwy7Zo6zhTTQ@mail.gmail.com>
Message-ID: <CALwzid=sBG=mZ_Qyjr-DTq4Tr+vMYif9ryFm4OZm4T1de1uBcw@mail.gmail.com>

On Sun, Mar 9, 2014 at 4:08 PM, Dan Stromberg <drsalists at gmail.com> wrote:
> On Sun, Mar 9, 2014 at 2:43 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> Dan Stromberg <drsalists at gmail.com>:
>>
>>> On Sun, Mar 9, 2014 at 2:32 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>>> There is no O(1) hash table.
>>>
>>> http://stackoverflow.com/questions/2771368/can-hash-tables-really-be-o1
>>
>> Please elaborate.
>
> A hash table of fixed size is O(1) until you fill it so full that you
> start getting enough collisions to make it O(n), as one bucket becomes
> a linked list.  This is because the hash function is O(1), and looking
> up a value in a C array is O(1).
>
> A more flexible hash table will not have a fixed size; instead it will
> grow itself as needed.  This growth operation tends to be O(n), but
> happens vanishingly infrequently as the table grows, so it's still
> amortized O(1).

A hash table can also only ever be O(1) in the average case.  Worst
case, everything you put into the hash table has the same hash value,
and so the time to fetch an item is entirely dependent on the
collision resolution scheme -- e.g. O(n) if a linked list or linear
probe is used, or perhaps O(log n) if each bucket is a balanced binary
tree.

There are schemes such as cuckoo hashing that allow true O(1) worst
case access, but they have other drawbacks -- inserts with cuckoo
hashing are amortized O(1), and it is even possible for an insert to
fail entirely after spending exponential time trying to find a way to
arrange things.


From nispray at gmail.com  Sun Mar  9 21:06:39 2014
From: nispray at gmail.com (Wesley)
Date: Sun, 9 Mar 2014 18:06:39 -0700 (PDT)
Subject: gdb unable to read python frame information
In-Reply-To: <mailman.7955.1394377206.18130.python-list@python.org>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <mailman.7955.1394377206.18130.python-list@python.org>
Message-ID: <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>

What's information do you want?

I told the OS, gdb and python version.

And my operation steps.

What do you want more, then, I can type here.

Wesley


From breamoreboy at yahoo.co.uk  Sun Mar  9 21:48:41 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 10 Mar 2014 01:48:41 +0000
Subject: gdb unable to read python frame information
In-Reply-To: <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <mailman.7955.1394377206.18130.python-list@python.org>
 <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>
Message-ID: <lfj5la$l3t$1@ger.gmane.org>

On 10/03/2014 01:06, Wesley wrote:
> What's information do you want?
>
> I told the OS, gdb and python version.
>
> And my operation steps.
>
> What do you want more, then, I can type here.
>
> Wesley
>

Context, you just keep sending messages like the above which on its own 
is meaningless.  Why should anybody answer your question when you can't 
be bothered to supply all the needed data in one hit?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From steve+comp.lang.python at pearwood.info  Sun Mar  9 22:37:05 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 10 Mar 2014 02:37:05 GMT
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
Message-ID: <531d2551$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sun, 09 Mar 2014 17:42:42 -0600, Ian Kelly wrote:

> On Sun, Mar 9, 2014 at 4:03 PM, Gregory Ewing
> <greg.ewing at canterbury.ac.nz> wrote:

>> Note that it says "when possible", not "if the implementation feels
>> like it".
> 
> That's quite vague, and not much stronger a guarantee than "maybe". It's
> technically "possible" for this augmented assignment to be performed in
> place:
> 
> x = 12
> x += 4
>
> But it's not done in-place, because ints are meant to be immutable. 

That's incorrect. Ints aren't merely "meant" to be immutable, which 
implies that's it's optional, they are defined by the language 
specification and the reference implementation as immutable. Any 
interpreter where ints are mutable *is not Python*.


> In any case, this means that whether the operation is actually performed
> in-place is an implementation detail -- if not of the Python
> implementation then at least of the class -- and not something the user
> should take for granted.

Whether += operates in place or not is part of the interface of the 
class, not the implementation.

Would you say that whether list.append operates in place or creates a new 
list is an implementation detail? Whether str.upper() creates a new 
string or modifies the existing one in place? Mutability versus 
immutability is part of the interface, not implementation, not 
withstanding that somebody could create an alternative class with the 
opposite behaviour: a MutableStr, or ImmutableList.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From nispray at gmail.com  Sun Mar  9 22:54:56 2014
From: nispray at gmail.com (Wesley)
Date: Sun, 9 Mar 2014 19:54:56 -0700 (PDT)
Subject: gdb unable to read python frame information
In-Reply-To: <mailman.7976.1394416133.18130.python-list@python.org>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <mailman.7955.1394377206.18130.python-list@python.org>
 <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>
 <mailman.7976.1394416133.18130.python-list@python.org>
Message-ID: <ba897815-b155-4537-a51a-ea16b4b725c9@googlegroups.com>

If you don't read the loop from the top, and don't tell me exactly what you want by just keep saying context, please ingore this post.

Thanks.
Wesley

? 2014?3?10????UTC+8??9?48?41??Mark Lawrence???
> On 10/03/2014 01:06, Wesley wrote:
> 
> > What's information do you want?
> 
> >
> 
> > I told the OS, gdb and python version.
> 
> >
> 
> > And my operation steps.
> 
> >
> 
> > What do you want more, then, I can type here.
> 
> >
> 
> > Wesley
> 
> >
> 
> 
> 
> Context, you just keep sending messages like the above which on its own 
> 
> is meaningless.  Why should anybody answer your question when you can't 
> 
> be bothered to supply all the needed data in one hit?
> 
> 
> 
> -- 
> 
> My fellow Pythonistas, ask not what our language can do for you, ask 
> 
> what you can do for our language.
> 
> 
> 
> Mark Lawrence
> 
> 
> 
> ---
> 
> This email is free from viruses and malware because avast! Antivirus protection is active.
> 
> http://www.avast.com



From breamoreboy at yahoo.co.uk  Sun Mar  9 23:11:57 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 10 Mar 2014 03:11:57 +0000
Subject: gdb unable to read python frame information
In-Reply-To: <ba897815-b155-4537-a51a-ea16b4b725c9@googlegroups.com>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <mailman.7955.1394377206.18130.python-list@python.org>
 <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>
 <mailman.7976.1394416133.18130.python-list@python.org>
 <ba897815-b155-4537-a51a-ea16b4b725c9@googlegroups.com>
Message-ID: <lfjags$10f$1@ger.gmane.org>

On 10/03/2014 02:54, Wesley wrote:
> If you don't read the loop from the top, and don't tell me exactly what you want by just keep saying context, please ingore this post.
>
> Thanks.
> Wesley
>
> ? 2014?3?10????UTC+8??9?48?41??Mark Lawrence???
>> On 10/03/2014 01:06, Wesley wrote:
>>
>>> What's information do you want?
>>
>>>
>>
>>> I told the OS, gdb and python version.
>>
>>>
>>
>>> And my operation steps.
>>
>>>
>>
>>> What do you want more, then, I can type here.
>>
>>>
>>
>>> Wesley
>>
>>>
>>
>>
>>
>> Context, you just keep sending messages like the above which on its own
>>
>> is meaningless.  Why should anybody answer your question when you can't
>>
>> be bothered to supply all the needed data in one hit?
>>
>>
>>
>> --
>>
>> My fellow Pythonistas, ask not what our language can do for you, ask
>>
>> what you can do for our language.
>>
>>
>>
>> Mark Lawrence
>>
>>
>>
>> ---
>>
>> This email is free from viruses and malware because avast! Antivirus protection is active.
>>
>> http://www.avast.com
>

Ah, that explains things, you're using the notoriously bug ridden google 
groups.  You could read and action this 
https://wiki.python.org/moin/GoogleGroupsPython but I'd suggest you 
equip yourself with a decent email client.  Thunderbird comes highly 
recommended.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From breamoreboy at yahoo.co.uk  Sun Mar  9 23:16:10 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 10 Mar 2014 03:16:10 +0000
Subject: Windows installation problem with 3.3.5
Message-ID: <lfjaob$5vi$1@ger.gmane.org>

It looks as if the upgrade from 3.3.4 to 3.3.5 has stolen my copies of 
py.exe and pyw.exe from c:\windows.  Before I raise an issue on the bug 
tracker could someone please confirm this, as it wouldn't be the first 
time I've managed to screw something up.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From steve+comp.lang.python at pearwood.info  Sun Mar  9 23:24:08 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 10 Mar 2014 03:24:08 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
Message-ID: <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sun, 09 Mar 2014 23:32:54 +0200, Marko Rauhamaa wrote:

> Dan Stromberg <drsalists at gmail.com>:
> 
>> This is not just a detail: O(1) tends to be beat O(logn) pretty easily
>> for large n.
> 
> There is no O(1) hash table.

Of course there are.

While it is true that hash tables *in general* are not *always* O(1), the 
claim that hash tables are O(1) is *less wrong* than your claim that 
there is "no O(1) hash table".

Proof: I create a hash table that accepts unsigned bytes as keys, where 
the hash is the value of the byte. So byte 0x42 hashes to 0x42, or 
decimal 66. I give the hash table 256 slots, numbered from 0 to 255. 
Every hash takes constant time, there are no collisions at all, lookups, 
insertions and deletions all take constant time regardless of how full 
the table is. The best, worst and average cases are not just O(1) but 
also ?(1).

Since I have proven that there is *at least one* hash table that is O(1) 
for best, worst and average case, your claim there are no such hash 
tables is completely wrong, and certainly more wrong than the claim that 
Python dicts are O(1) (which is only a little bit wrong, but typically 
right).

See also "The Relativity Of Wrong":

http://chem.tufts.edu/answersinscience/relativityofwrong.htm




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Sun Mar  9 23:24:13 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 10 Mar 2014 03:24:13 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <mailman.7965.1394401067.18130.python-list@python.org>
 <8761nnrqsk.fsf@elektro.pacujo.net>
 <CAGGBd_oSgZgtsg52JBDhSUxuxHpi9ZJSw4WfOwGwy7Zo6zhTTQ@mail.gmail.com>
 <mailman.7975.1394409929.18130.python-list@python.org>
Message-ID: <531d305d$1$29994$c3e8da3$5496439d@news.astraweb.com>

On Sun, 09 Mar 2014 18:04:46 -0600, Ian Kelly wrote:

> On Sun, Mar 9, 2014 at 4:08 PM, Dan Stromberg <drsalists at gmail.com>
> wrote:
>> On Sun, Mar 9, 2014 at 2:43 PM, Marko Rauhamaa <marko at pacujo.net>
>> wrote:
>>> Dan Stromberg <drsalists at gmail.com>:
>>>
>>>> On Sun, Mar 9, 2014 at 2:32 PM, Marko Rauhamaa <marko at pacujo.net>
>>>> wrote:
>>>>> There is no O(1) hash table.
>>>>
>>>> http://stackoverflow.com/questions/2771368/can-hash-tables-really-be-
o1
>>>
>>> Please elaborate.
>>
>> A hash table of fixed size is O(1) until you fill it so full that you
>> start getting enough collisions to make it O(n), as one bucket becomes
>> a linked list.  This is because the hash function is O(1), and looking
>> up a value in a C array is O(1).
>>
>> A more flexible hash table will not have a fixed size; instead it will
>> grow itself as needed.  This growth operation tends to be O(n), but
>> happens vanishingly infrequently as the table grows, so it's still
>> amortized O(1).
> 
> A hash table can also only ever be O(1) in the average case.

Since this discussion has apparently devolved into people trying to out-
pedant each other, I'm going to dispute that. That will depend on the 
distribution of hash collisions. With a sufficiently big table, 
sufficiently small set of possible data, a sufficiently good hash 
function, or some combination of the above, a hash table may be O(1) even 
in the worst case.

E.g. if you hash a number n to itself, e.g. hash(42) == 42, your data 
consists of single byte numbers 0 through 255, and your hash table has 
256 slots, *there are no collisions* and every lookup is O(1).

There are technical meanings for Big Oh notation, which can be quite 
complicated. There's Big O, Little o, Big ? (omega), Little ? (omega), 
Big ? (theta), although I don't think there's a Little ?. They can refer 
to the best case, worst case, average (mean) case, median case, "typical" 
case where you're making some guess of what occurs typically, and any 
other situation you care about. The algorithmic complexity can apply 
consistently to each and every run of the algorithm, or they can be 
amortized over many runs. If you're doing a technical analysis of an 
algorithm, this pedantic detail is important.

But when people are just talking informally in a hand-wavy manner, they 
usually say "O(foo)" when they actually mean "for typical data under 
typical conditions, the algorithm runs with a complexity of the order of 
foo". And that's perfectly okay, just like it's perfectly okay to 
describe the Earth as a sphere even though a pedant will call it a 
wrinkly asymmetrical oblate spheroid.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From flebber.crue at gmail.com  Mon Mar 10 00:49:20 2014
From: flebber.crue at gmail.com (flebber)
Date: Sun, 9 Mar 2014 21:49:20 -0700 (PDT)
Subject: golang OO removal,  benefits. over python?
Message-ID: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>

I was wondering if a better programmer than I could explain if the removal of OO features in golang really does offer an great benefit over python.

An article I was reading ran through a brief overview of golang in respect of OO features http://areyoufuckingcoding.me/2012/07/25/object-desoriented-language/
.

maybe removing OO features would be a benefit to c++ users or Java users but python?

As I have seen an interesting reddit or two of people trying to figure out go today it was a ruby user, totally lost with structs.

So anecdotally is actually python and ruby users changing to Go, here is a blog and reddit from Rob Pike. http://www.reddit.com/comments/1mue70

Why would a Python user change to go except for new and interesting?

Sayth


From rustompmody at gmail.com  Mon Mar 10 01:05:59 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Sun, 9 Mar 2014 22:05:59 -0700 (PDT)
Subject: golang OO removal,  benefits. over python?
In-Reply-To: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
References: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
Message-ID: <897574dd-e115-4056-88d3-20a4cf82191f@googlegroups.com>

On Monday, March 10, 2014 10:19:20 AM UTC+5:30, flebber wrote:
> I was wondering if a better programmer than I could explain if the removal of OO features in golang really does offer an great benefit over python.

That's a strange locution: You are suggesting that go had OOP and it was removed


From marko at pacujo.net  Mon Mar 10 02:16:43 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 10 Mar 2014 08:16:43 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87eh2atw6s.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> Proof: I create a hash table that accepts unsigned bytes as keys, where 

The O(f(n)) notation has no meaning when n is limited.

This thing is not just pedantry. The discussion was how a balanced tree
fares in comparison with hash tables. A simplistic O(1) vs O(log n) was
presented as a proof that balanced trees don't have a chance in practice
or theory. I wasn't so easily convinced.


Marko


From dieter at handshake.de  Mon Mar 10 03:13:42 2014
From: dieter at handshake.de (dieter)
Date: Mon, 10 Mar 2014 08:13:42 +0100
Subject: gdb unable to read python frame information
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <87mwh2bi1v.fsf@handshake.de>
 <mailman.7900.1394198618.18130.python-list@python.org>
 <73e3cfa2-28d3-4647-8a7f-577e41dffbd1@googlegroups.com>
 <mailman.7932.1394288074.18130.python-list@python.org>
 <6dc8a38d-d3a6-44fd-8f39-f73cea1ac4c1@googlegroups.com>
Message-ID: <8738iqpluh.fsf@handshake.de>

Wesley <nispray at gmail.com> writes:

> So, let me clarify here, in order to try, I get a clean machine.
>
> Centos 6.5 64bit.
> Now , I try this:
> 1. install gdb 7.7 from source , with configure option --with-python
>
> 2. install python 2.6.6 from source, with configure option --with-pydebug
>
> 3. run a python script
>
> 4. from command line, gdb python -p <pid> to attach the running script
>
> 5. within gdb, issue python, import libpython, end 
>   no errors
> 6. py-bt outputs nothing, py-locals says Unable to locate python frame
> here is the snippet:
> [root at localhost Python-2.6.6]# gdb python 52315
> GNU gdb (GDB) 7.7
> ....
> Attaching to program: /home/nipen/test/Python-2.6.6/python, process 52315
> Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
> Loaded symbols for /lib64/ld-linux-x86-64.so.2
> 0x00000030a98e15c3 in ?? ()
> (gdb) bt
> #0  0x00000030a98e15c3 in ?? ()
> #1  0x00007f4cf68d1219 in ?? ()
> #2  0x0000000000000000 in ?? ()

This looks like a very strange backtrace on C level as well.

The most natural explanation would be: your process is in a very strange
state (due to some C level problem). But, of course, your
"gdb" might have general problems, as well.



From dieter at handshake.de  Mon Mar 10 03:16:41 2014
From: dieter at handshake.de (dieter)
Date: Mon, 10 Mar 2014 08:16:41 +0100
Subject: gdb unable to read python frame information
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <mailman.7955.1394377206.18130.python-list@python.org>
 <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>
 <lfj5la$l3t$1@ger.gmane.org>
Message-ID: <87y50io752.fsf@handshake.de>

Mark Lawrence <breamoreboy at yahoo.co.uk> writes:
> On 10/03/2014 01:06, Wesley wrote:
> ...
> Context, you just keep sending messages like the above which on its
> own is meaningless.

The original poster has send messages lacking important pieces
of information -- but on request from the list, he has fixed this
initial error. Thus, on his side, there was progress ;-)



From dieter at handshake.de  Mon Mar 10 03:28:30 2014
From: dieter at handshake.de (dieter)
Date: Mon, 10 Mar 2014 08:28:30 +0100
Subject: gdb unable to read python frame information
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <mailman.7955.1394377206.18130.python-list@python.org>
 <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>
 <mailman.7976.1394416133.18130.python-list@python.org>
 <ba897815-b155-4537-a51a-ea16b4b725c9@googlegroups.com>
Message-ID: <87txb6o6ld.fsf@handshake.de>

Wesley <nispray at gmail.com> writes:

> If you don't read the loop from the top, and don't tell me exactly what you want by just keep saying context, please ingore this post.

You are doing things only a few people do: trying to debug
a Python process on C level -- and you observe really strange things.
It is very difficult to guess from the distance what goes wrong.

Apparently, your gdb sees a very strange state of the debugged
process. But why?

Missing symbols was the first guess (the
gdb output you have provided does not suggest this - but
I have not seen the "reading symbols from "python" ..."; thus,
there may still be a problem with this).

A runaway process is another guess.

Some gdb problem another one.


I would approach the situation by simplifying the setup.
Instead of attaching a running Python process, I would
use "gdb python"; then "run"; then "CTRL-C" and there look
what "bt" gives you (this should demonstrate whether your
"gdb" is set up correctly and can debug Python on C level).
Then you write an infinitely running function in Python,
run it and again interrupt with "gdb" to see whether the "py-*"
commands are working. If this all work, you come again
to your actual task -- understanding what your python process
is doing.



From larry at hastings.org  Mon Mar 10 03:47:05 2014
From: larry at hastings.org (Larry Hastings)
Date: Mon, 10 Mar 2014 00:47:05 -0700
Subject: [RELEASED] Python 3.4.0 release candidate 3
Message-ID: <531D6DF9.1020305@hastings.org>



On behalf of the Python development team, I'm pleased to announce
the third and final** release candidate of Python 3.4.

This is a preview release, and its use is not recommended for
production settings.

Python 3.4 includes a range of improvements of the 3.x series, including
hundreds of small improvements and bug fixes.  Major new features and
changes in the 3.4 release series include:

* PEP 428, a "pathlib" module providing object-oriented filesystem paths
* PEP 435, a standardized "enum" module
* PEP 436, a build enhancement that will help generate introspection
            information for builtins
* PEP 442, improved semantics for object finalization
* PEP 443, adding single-dispatch generic functions to the standard library
* PEP 445, a new C API for implementing custom memory allocators
* PEP 446, changing file descriptors to not be inherited by default
            in subprocesses
* PEP 450, a new "statistics" module
* PEP 451, standardizing module metadata for Python's module import system
* PEP 453, a bundled installer for the *pip* package manager
* PEP 454, a new "tracemalloc" module for tracing Python memory allocations
* PEP 456, a new hash algorithm for Python strings and binary data
* PEP 3154, a new and improved protocol for pickled objects
* PEP 3156, a new "asyncio" module, a new framework for asynchronous I/O

Python 3.4 is now in "feature freeze", meaning that no new features will be
added.  The final release is projected for March 16, 2014.


To download Python 3.4.0rc3 visit:

     http://www.python.org/download/releases/3.4.0/


Please consider trying Python 3.4.0rc3 with your code and reporting any
new issues you notice to:

      http://bugs.python.org/


Enjoy!


** This time we really mean it!  No foolin'!

--
Larry Hastings, Release Manager
larry at hastings.org
(on behalf of the entire python-dev team and 3.4's contributors)


From ian.g.kelly at gmail.com  Mon Mar 10 03:50:22 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 10 Mar 2014 01:50:22 -0600
Subject: golang OO removal, benefits. over python?
In-Reply-To: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
References: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
Message-ID: <CALwzidkJ=cWxRwimKVOZbVftnaJ236RCLtM8-n+1LXPjdg5BFg@mail.gmail.com>

On Sun, Mar 9, 2014 at 10:49 PM, flebber <flebber.crue at gmail.com> wrote:
> I was wondering if a better programmer than I could explain if the removal of OO features in golang really does offer an great benefit over python.
>
> An article I was reading ran through a brief overview of golang in respect of OO features http://areyoufuckingcoding.me/2012/07/25/object-desoriented-language/

The description of how Go structs work is accurate from what I know of
it, but I think the author goes astray in claiming that this is not
OOP.

If you look at how C++ compiles inherited classes, it works in
basically the same way.  The SmallBox class in C++ is essentially a
struct with its fields laid out in a specific order and some methods
that operate on it.  A BigBox class that inherits from SmallBox will
first lay out the SmallBox fields in the same way that SmallBox does,
and then add the fields specific to BigBox after.  Draw an imaginary
line around the SmallBox fields, and you have the same setup as the Go
example: a SmallBox nested within a BigBox.  SmallBox methods will
only operate on the portion of BigBox that is within the imaginary
line (i.e. the SmallBox) and don't need to have any knowledge that the
SmallBox is part of a larger data structure.  BigBox methods can
operate on the entire BigBox and can call SmallBox methods when
desired.

The author points out that nested structures can be made optional by
including a pointer to the structure instead of the structure itself.
Again you can do the exact same thing in C++; in OOP this is usually
described as a "has-a" relationship.  Most languages don't support the
syntactic sugar that makes this look almost identical to inheritance
in Go, but that's all it is.

The biggest difference between the two is that Go doesn't have any
concept of virtual methods.  A call of a SmallBox method on a SmallBox
object, whether part of a larger object or not, will always call that
SmallBox method.  Whereas a call to a C++ method that is compiled as a
virtual method will actually call the method associated with the
superstructure, regardless of the static type the method was called
on.  Go gets around this by using interfaces.  An interface that is
satisfied by SmallBox will usually automatically be satisfied by
BigBox also, and calls to interface methods are dispatched
dynamically.  As a result, object-oriented Go code will typically work
with interfaces rather than specifying actual classes, which is not
too different from how Java code is typically written.

Incidentally, I rather like the design of Go interfaces.  They are
essentially Python's duck typing made explicit, divorcing interface
implementation from formal inheritance.  On the whole though I think
that the language is not yet mature enough to be able to seriously
compete with more established languages like Python or Java.


From ian.g.kelly at gmail.com  Mon Mar 10 04:35:36 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 10 Mar 2014 02:35:36 -0600
Subject: Tuples and immutability
In-Reply-To: <531d2551$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
 <531d2551$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALwzidkeENWM7sSDOFwkfzJzUqFXO+TbUZ=zkZW+Q5YRkRdm5A@mail.gmail.com>

On Sun, Mar 9, 2014 at 8:37 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Sun, 09 Mar 2014 17:42:42 -0600, Ian Kelly wrote:
>
>> On Sun, Mar 9, 2014 at 4:03 PM, Gregory Ewing
>> <greg.ewing at canterbury.ac.nz> wrote:
>
>>> Note that it says "when possible", not "if the implementation feels
>>> like it".
>>
>> That's quite vague, and not much stronger a guarantee than "maybe". It's
>> technically "possible" for this augmented assignment to be performed in
>> place:
>>
>> x = 12
>> x += 4
>>
>> But it's not done in-place, because ints are meant to be immutable.
>
> That's incorrect. Ints aren't merely "meant" to be immutable, which
> implies that's it's optional, they are defined by the language
> specification and the reference implementation as immutable. Any
> interpreter where ints are mutable *is not Python*.

That's true, but is beside the point, which is that "when possible" is
not very meaningful.

>> In any case, this means that whether the operation is actually performed
>> in-place is an implementation detail -- if not of the Python
>> implementation then at least of the class -- and not something the user
>> should take for granted.
>
> Whether += operates in place or not is part of the interface of the
> class, not the implementation.
>
> Would you say that whether list.append operates in place or creates a new
> list is an implementation detail? Whether str.upper() creates a new
> string or modifies the existing one in place?

Of course not.  list.append is documented as modifying the list.
str.upper is documented as returning a copy of the string.

> Mutability versus
> immutability is part of the interface, not implementation, not
> withstanding that somebody could create an alternative class with the
> opposite behaviour: a MutableStr, or ImmutableList.

If the in-place behavior of += is held to be part of the interface,
then we must accept that += is not polymorphic across mutable and
immutable types, which in my mind largely* defeats the purpose of
having it.  After all, there should be one -- and preferably only one
-- obvious way to do it.  If you want in-place concatenation, the
obvious way to do it is by calling extend.  If you want copy
concatenation, the obvious way to do it is with the + operator.  Why
then should not just mutable sequences but immutable sequences as well
even offer the += operator?

* The one exception I can think of is numpy, where there is no more
obvious way to do in-place addition, and in that context I would
consider the in-place behavior to be part of the interface.


From mail at timgolden.me.uk  Mon Mar 10 04:36:54 2014
From: mail at timgolden.me.uk (Tim Golden)
Date: Mon, 10 Mar 2014 08:36:54 +0000
Subject: Windows installation problem with 3.3.5
In-Reply-To: <lfjaob$5vi$1@ger.gmane.org>
References: <lfjaob$5vi$1@ger.gmane.org>
Message-ID: <531D79A6.3010502@timgolden.me.uk>

On 10/03/2014 03:16, Mark Lawrence wrote:
> It looks as if the upgrade from 3.3.4 to 3.3.5 has stolen my copies of
> py.exe and pyw.exe from c:\windows.  Before I raise an issue on the bug
> tracker could someone please confirm this, as it wouldn't be the first
> time I've managed to screw something up.

Well, as unhelpful as this might be, it gave me no problem:

<dump>

c:\Windows>dir py.exe
 Volume in drive C has no label.
 Volume Serial Number is 787D-BE54

 Directory of c:\Windows

18/11/2013  21:17            93,696 py.exe
               1 File(s)         93,696 bytes
               0 Dir(s)  31,048,863,744 bytes free

[... snip installing Python 3.3.5 ...]

c:\Windows>dir py.exe
 Volume in drive C has no label.
 Volume Serial Number is 787D-BE54

 Directory of c:\Windows

09/03/2014  10:36            93,696 py.exe
               1 File(s)         93,696 bytes
               0 Dir(s)  31,048,912,896 bytes free

</dump>

TJG


From marko at pacujo.net  Mon Mar 10 04:38:58 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 10 Mar 2014 10:38:58 +0200
Subject: golang OO removal, benefits. over python?
References: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
 <mailman.7983.1394437871.18130.python-list@python.org>
Message-ID: <878usitplp.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> The description of how Go structs work is accurate from what I know of
> it, but I think the author goes astray in claiming that this is not
> OOP.

Call it "no-nonsense OOP." No wonder the color of the box was gray in
the example.

> On the whole though I think that the language is not yet mature enough
> to be able to seriously compete with more established languages like
> Python or Java.

Also, is there anything seriously lacking in Python, Java and C?

I was very interested in Go when it came out, but was turned off by the
fact that you had so have a Google account to effectively participate in
the community.


Marko


From mail at timgolden.me.uk  Mon Mar 10 04:40:01 2014
From: mail at timgolden.me.uk (Tim Golden)
Date: Mon, 10 Mar 2014 08:40:01 +0000
Subject: Windows installation problem with 3.3.5
In-Reply-To: <lfjaob$5vi$1@ger.gmane.org>
References: <lfjaob$5vi$1@ger.gmane.org>
Message-ID: <531D7A61.1090603@timgolden.me.uk>

On 10/03/2014 03:16, Mark Lawrence wrote:
> It looks as if the upgrade from 3.3.4 to 3.3.5 has stolen my copies of
> py.exe and pyw.exe from c:\windows.  Before I raise an issue on the bug
> tracker could someone please confirm this, as it wouldn't be the first
> time I've managed to screw something up.

<random ill-educated guesswork>
One thing does occur to me: I seem to remember that you have in the past
installed py[w].exe from Vinay's standalone installer. If that was the
case, it's presumably possible that some mechanism of the Python 3.3.5
.msi removed them and didn't replace them with its own versions?
</random ill-educated guesswork>

TJG


From steve+comp.lang.python at pearwood.info  Mon Mar 10 04:53:07 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 10 Mar 2014 08:53:07 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
Message-ID: <531d7d73$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Mon, 10 Mar 2014 08:16:43 +0200, Marko Rauhamaa wrote:

> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
> 
>> Proof: I create a hash table that accepts unsigned bytes as keys, where
> 
> The O(f(n)) notation has no meaning when n is limited.

It has obvious meaning: O(1) means that look-ups take constant time, not 
(for example) proportional to the number of keys in the table.


> This thing is not just pedantry. 

Yes it is. You're not even being pedantic for the sake of educating 
people and helping them learn. If that were the case, I would completely 
understand. Rather, it looks to me that you're being obnoxiously pedantic 
for the sake of trying to get attention. I think you are trolling. Take 
your comment that started this dispute:

    [responding to Dan Stromberg]
    > This is not just a detail: O(1) tends to be beat O(logn) 
    > pretty easily for large n.

    [to which your entire response was]
    There is no O(1) hash table.


As pedantry, it is an utter failure: it's *wrong*, for starters, but you 
didn't even make a pretence of trying to justify it. It's not 
educational, and it doesn't advance your argument in any way. And just 
*two posts later*, you acknowledged without apology or embarrassment that 
hash tables actually are O(1). So it seems that you didn't even believe 
your claim when you made it. This is why I think you are trolling.

All your comment accomplished was to wrongly contradict a well-
established and often-repeated fact that hash tables are usually O(1):

https://duckduckgo.com/html/?q=big+oh+hash+tables

which is great if your aim is to trick people into giving you attention 
(as I suppose I am giving you attention now) but useless for advancing 
the debate or educating people.

It is as if you had declared "Actually the Allies had lost World War 
Two", and then tried to justify such a ridiculously false statement on 
the basis that while they didn't actually *lose* according to the 
normally accepted meaning of the word, some of the Allies may have failed 
to accomplish every single one of their objectives in the war.


> The discussion was how a balanced tree
> fares in comparison with hash tables. A simplistic O(1) vs O(log n) was
> presented as a proof that balanced trees don't have a chance in practice
> or theory. I wasn't so easily convinced.

If you had wanted to put the case for balanced trees, you could mention 
that in practice they perform comparably to hash tables for reasonable 
sizes of data, and may require less memory. You could have made an 
attempt to teach people about the difference between O and ? complexity, 
the difference between best case, worst case, average case, and typical 
behaviour. You could have mentioned the difference between amortized and 
non-amortized behaviour, or go into detail about the various assumptions 
made when doing Big Oh analysis (e.g. that all "simple" operations take 
constant time, which is not strictly speaking true).

Any of these things would have helped people understand your position 
better. But you did *none* of these things. It seems to me that your 
stated position is actually irrelevant to you, what you want is not 
better data structures in Python, but for people to respond to your posts.

In other words, I suspect you are trolling.

If I am right, that certainly would explain your apparent inability to 
understand the difference between "is" and == operators, your insistence 
that object IDs are addresses, and your declaration that object identity 
is philosophically untenable.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From jurko.gospodnetic at pke.hr  Mon Mar 10 05:05:00 2014
From: jurko.gospodnetic at pke.hr (=?UTF-8?B?SnVya28gR29zcG9kbmV0acSH?=)
Date: Mon, 10 Mar 2014 10:05:00 +0100
Subject: Windows installation problem with 3.3.5
In-Reply-To: <lfjaob$5vi$1@ger.gmane.org>
References: <lfjaob$5vi$1@ger.gmane.org>
Message-ID: <lfjv7d$bgm$1@ger.gmane.org>

   Hi.

On 10.3.2014. 4:16, Mark Lawrence wrote:
 > It looks as if the upgrade from 3.3.4 to 3.3.5 has stolen my copies of
 > py.exe and pyw.exe from c:\windows.  Before I raise an issue on the
 > bug tracker could someone please confirm this, as it wouldn't be the
 > first time I've managed to screw something up.

What exactly do you mean by 'stolen'? Removed those executables? Or 
reused the original ones instead of new ones you expected to be 
installed over them? Or the opposite - overwrote them with new ones and 
you expected the old ones to stay around?

   I just tested the same thing and the original executables that were 
there got overwritten with newer ones, as I expected.

   Hope this helps.

   Best regards,
     Jurko Gospodneti?




From steve+comp.lang.python at pearwood.info  Mon Mar 10 05:13:40 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 10 Mar 2014 09:13:40 GMT
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
 <531d2551$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7984.1394440586.18130.python-list@python.org>
Message-ID: <531d8244$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Mon, 10 Mar 2014 02:35:36 -0600, Ian Kelly wrote:

> On Sun, Mar 9, 2014 at 8:37 PM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> On Sun, 09 Mar 2014 17:42:42 -0600, Ian Kelly wrote:
>>
>>> On Sun, Mar 9, 2014 at 4:03 PM, Gregory Ewing
>>> <greg.ewing at canterbury.ac.nz> wrote:
>>
>>>> Note that it says "when possible", not "if the implementation feels
>>>> like it".
>>>
>>> That's quite vague, and not much stronger a guarantee than "maybe".
>>> It's technically "possible" for this augmented assignment to be
>>> performed in place:
>>>
>>> x = 12
>>> x += 4
>>>
>>> But it's not done in-place, because ints are meant to be immutable.
>>
>> That's incorrect. Ints aren't merely "meant" to be immutable, which
>> implies that's it's optional, they are defined by the language
>> specification and the reference implementation as immutable. Any
>> interpreter where ints are mutable *is not Python*.
> 
> That's true, but is beside the point, which is that "when possible" is
> not very meaningful.

It's meaningful. It refers not to ints, but the infinite number of 
possible classes which might include augmented assignment. Some of them 
will be immutable, in which case it is not possible for += etc. to be 
performed in-place. Some of them will be mutable, but there won't be any 
reasonable (or even unreasonable) way to perform += in-place.

But for some mutable classes, it will be possible to perform += in place, 
in which case the docs say that they have to do so.


>>> In any case, this means that whether the operation is actually
>>> performed in-place is an implementation detail -- if not of the Python
>>> implementation then at least of the class -- and not something the
>>> user should take for granted.
>>
>> Whether += operates in place or not is part of the interface of the
>> class, not the implementation.
>>
>> Would you say that whether list.append operates in place or creates a
>> new list is an implementation detail? Whether str.upper() creates a new
>> string or modifies the existing one in place?
> 
> Of course not.  list.append is documented as modifying the list.
> str.upper is documented as returning a copy of the string.

Right. And += is documented as modifying the list too.


>> Mutability versus
>> immutability is part of the interface, not implementation, not
>> withstanding that somebody could create an alternative class with the
>> opposite behaviour: a MutableStr, or ImmutableList.
> 
> If the in-place behavior of += is held to be part of the interface, then
> we must accept that += is not polymorphic across mutable and immutable
> types, 

I'm fine with that.


> which in my mind largely* defeats the purpose of having it. 

Not to my mind. I think that having augmented assignment is worthwhile 
even if it behaves differently and incompatibly for different classes. 
After all, so does * (multiplication):

py> x = 24
py> x*x
576

but: 

py> x = []
py> x*x
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can't multiply sequence by non-int of type 'list'


I don't think that we ought to throw away * and I don't think we ought to 
throw away *= either.


> After all, there should be one -- and preferably only one -- obvious way
> to do it.  If you want in-place concatenation, the obvious way to do it
> is by calling extend.  If you want copy concatenation, the obvious way
> to do it is with the + operator.  Why then should not just mutable
> sequences but immutable sequences as well even offer the += operator?

*shrug*

I can see that each individual operation:

    list.extend
    list +
    list += 

makes good sense in isolation, but I can also see that the combination 
don't quite gel together as smoothly as we might hope.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From breamoreboy at yahoo.co.uk  Mon Mar 10 05:32:35 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 10 Mar 2014 09:32:35 +0000
Subject: Windows installation problem with 3.3.5
In-Reply-To: <531D7A61.1090603@timgolden.me.uk>
References: <lfjaob$5vi$1@ger.gmane.org> <531D7A61.1090603@timgolden.me.uk>
Message-ID: <lfk0r8$sdu$2@ger.gmane.org>

On 10/03/2014 08:40, Tim Golden wrote:
> On 10/03/2014 03:16, Mark Lawrence wrote:
>> It looks as if the upgrade from 3.3.4 to 3.3.5 has stolen my copies of
>> py.exe and pyw.exe from c:\windows.  Before I raise an issue on the bug
>> tracker could someone please confirm this, as it wouldn't be the first
>> time I've managed to screw something up.
>
> <random ill-educated guesswork>
> One thing does occur to me: I seem to remember that you have in the past
> installed py[w].exe from Vinay's standalone installer. If that was the
> case, it's presumably possible that some mechanism of the Python 3.3.5
> .msi removed them and didn't replace them with its own versions?
> </random ill-educated guesswork>
>
> TJG
>

Correct.  I'll flag this on the bug tracker just in case this is in fact 
the cause, though I can't off of the top of my head see why it should be.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From marko at pacujo.net  Mon Mar 10 05:41:41 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 10 Mar 2014 11:41:41 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <531d7d73$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <8738iqtmp6.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> If I am right, that certainly would explain your apparent inability to
> understand the difference between "is" and == operators, your
> insistence that object IDs are addresses, and your declaration that
> object identity is philosophically untenable.

You and I certainly have a very hard time communicating. Your
paraphrasing of my positions demonstrates that.


Marko


From breamoreboy at yahoo.co.uk  Mon Mar 10 05:51:17 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 10 Mar 2014 09:51:17 +0000
Subject: Balanced trees
In-Reply-To: <531d7d73$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <531d7d73$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lfk1ua$823$1@ger.gmane.org>

On 10/03/2014 08:53, Steven D'Aprano wrote:
>
> In other words, I suspect you are trolling.
>

s/suspect/know/ , he didn't make captain of my dream team for nothing, 
you know :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ned at nedbatchelder.com  Mon Mar 10 06:57:13 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Mon, 10 Mar 2014 06:57:13 -0400
Subject: Balanced trees
In-Reply-To: <8738iqtmp6.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <531d7d73$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <8738iqtmp6.fsf@elektro.pacujo.net>
Message-ID: <lfk5pr$ou9$1@ger.gmane.org>

On 3/10/14 5:41 AM, Marko Rauhamaa wrote:
> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
>
>> If I am right, that certainly would explain your apparent inability to
>> understand the difference between "is" and == operators, your
>> insistence that object IDs are addresses, and your declaration that
>> object identity is philosophically untenable.
>
> You and I certainly have a very hard time communicating. Your
> paraphrasing of my positions demonstrates that.
>

Marko, welcome to the community.  We enjoy technical discourse, even 
debate.  It's clear that you bring a lot of knowledge, intelligence, and 
passion.  But you have been involved in a number of long contentious 
threads in the last few weeks.

You are right that you and Steven have had a hard time communicating. 
You are part of "you and Steven", it would be at least polite to 
consider that part of the reason for the difficulty has to do with your 
style.  It can be brief and contrarian, which puts people off.  Perhaps 
if you tried to understand the gap and bridge it more, people would be 
less inclined to think that you were trying to widen the gap.

--Ned.

>
> Marko
>


-- 
Ned Batchelder, http://nedbatchelder.com



From flebber.crue at gmail.com  Mon Mar 10 07:45:17 2014
From: flebber.crue at gmail.com (flebber)
Date: Mon, 10 Mar 2014 04:45:17 -0700 (PDT)
Subject: golang OO removal, benefits. over python?
In-Reply-To: <878usitplp.fsf@elektro.pacujo.net>
References: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
 <mailman.7983.1394437871.18130.python-list@python.org>
 <878usitplp.fsf@elektro.pacujo.net>
Message-ID: <36c92dce-3b18-479b-85c6-31c48f11b25b@googlegroups.com>


> Also, is there anything seriously lacking in Python, Java and C?
> 
> 
> Marko

>From their FAQ:

Go was born out of frustration with existing languages and environments for systems programming. Programming had become too difficult and the choice of languages was partly to blame. One had to choose either efficient compilation, efficient execution, or ease of programming; all three were not available in the same mainstream language. Programmers who could were choosing ease over safety and efficiency by moving to dynamically typed languages such as Python and JavaScript rather than C++ or, to a lesser extent, Java.

Go is an attempt to combine the ease of programming of an interpreted, dynamically typed language with the efficiency and safety of a statically typed, compiled language. It also aims to be modern, with support for networked and multicore computing.

>
Although Go doesn't have exception handling either which is odd. http://blog.golang.org/error-handling-and-go
http://uberpython.wordpress.com/2012/09/23/why-im-not-leaving-python-for-go/
Or you can use defer http://blog.golang.org/defer-panic-and-recover
func CopyFile(dstName, srcName string) (written int64, err error) {
    src, err := os.Open(srcName)
    if err != nil {
        return
    }
    defer src.Close()

    dst, err := os.Create(dstName)
    if err != nil {
        return
    }
    defer dst.Close()

    return io.Copy(dst, src)
}

> That's a strange locution: You are suggesting that go had OOP and it was > > removed 
Although Go has types and methods and allows an object-oriented style of programming, there is no type hierarchy. The concept of "interface" in Go provides a different approach that we believe is easy to use and in some ways more general. There are also ways to embed types in other types to provide something analogous--but not identical--to subclassing. http://golang.org/doc/faq#Is_Go_an_object-oriented_language

sayth


From g.rodola at gmail.com  Mon Mar 10 07:56:39 2014
From: g.rodola at gmail.com (Giampaolo Rodola')
Date: Mon, 10 Mar 2014 12:56:39 +0100
Subject: ANN: psutil 2.0.0 released
Message-ID: <CAFYqXL_yVjWRv74WJrYqfi_e8fW6ozmhGxNXmBi21OSNnP=n+g@mail.gmail.com>

Hi there folks,
I'm pleased to announce the 2.0.0 release of psutil:
http://code.google.com/p/psutil/

=== About ===

psutil (python system and process utilities) is a cross-platform library
for retrieving information on running processes and system utilization
(CPU, memory, disks, network) in Python. It is useful mainly for system
monitoring, profiling and limiting process resources and management of
running processes. It implements many functionalities offered by command
line tools such as: ps, top, lsof, netstat, ifconfig, who, df, kill, free,
nice, ionice, iostat, iotop, uptime, pidof, tty, taskset, pmap. It
currently supports Linux, Windows, OSX, FreeBSD and Sun Solaris, both
32-bit and 64-bit architectures, with Python versions from 2.4 to 3.4. Pypi
is also known to work.

=== What changed ===

A lot. I tried to address all the changes in this blog post:
http://grodola.blogspot.com/2014/03/psutil-20.html


=== Links ===

* Home page: http://code.google.com/p/psutil
* Downloads:
https://pypi.python.org/pypi?:action=display&name=psutil#downloads
* Documentation: http://psutil.readthedocs.org/

Please try out this new release and let me know if you experience any
problem by filing issues on the bug tracker.

Best,

-- 
Giampaolo - http://grodola.blogspot.com
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From jurko.gospodnetic at pke.hr  Mon Mar 10 08:51:07 2014
From: jurko.gospodnetic at pke.hr (=?UTF-8?B?SnVya28gR29zcG9kbmV0acSH?=)
Date: Mon, 10 Mar 2014 13:51:07 +0100
Subject: Windows installation problem with 3.3.5
In-Reply-To: <lfjaob$5vi$1@ger.gmane.org>
References: <lfjaob$5vi$1@ger.gmane.org>
Message-ID: <lfkcfc$8ec$1@ger.gmane.org>

   Hi.

On 10.3.2014. 4:16, Mark Lawrence wrote:
> It looks as if the upgrade from 3.3.4 to 3.3.5 has stolen my copies of
> py.exe and pyw.exe from c:\windows.  Before I raise an issue on the bug
> tracker could someone please confirm this, as it wouldn't be the first
> time I've managed to screw something up.

   I just now ran into something that might explain this. You could have 
run your new installation as 'for the current user only'. That would not 
have placed the new py.exe executable in C:\Windows.

   Hope this helps.

   Best regards,
     Jurko Gospodneti?




From breamoreboy at yahoo.co.uk  Mon Mar 10 09:06:35 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 10 Mar 2014 13:06:35 +0000
Subject: Windows installation problem with 3.3.5
In-Reply-To: <lfkcfc$8ec$1@ger.gmane.org>
References: <lfjaob$5vi$1@ger.gmane.org> <lfkcfc$8ec$1@ger.gmane.org>
Message-ID: <lfkdcc$co4$1@ger.gmane.org>

On 10/03/2014 12:51, Jurko Gospodneti? wrote:
>    Hi.
>
> On 10.3.2014. 4:16, Mark Lawrence wrote:
>> It looks as if the upgrade from 3.3.4 to 3.3.5 has stolen my copies of
>> py.exe and pyw.exe from c:\windows.  Before I raise an issue on the bug
>> tracker could someone please confirm this, as it wouldn't be the first
>> time I've managed to screw something up.
>
>    I just now ran into something that might explain this. You could have
> run your new installation as 'for the current user only'. That would not
> have placed the new py.exe executable in C:\Windows.
>
>    Hope this helps.
>
>    Best regards,
>      Jurko Gospodneti?
>

Thanks for trying but no, I installed for all users.  FTR issue here 
http://bugs.python.org/issue20880

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From harrismh777 at gmail.com  Mon Mar 10 09:39:13 2014
From: harrismh777 at gmail.com (Mark H. Harris)
Date: Mon, 10 Mar 2014 06:39:13 -0700 (PDT)
Subject: image processing in python and opencv
In-Reply-To: <mailman.7960.1394392505.18130.python-list@python.org>
References: <512500c5-3c2f-49c8-861f-5755991c3abb@googlegroups.com>
 <mailman.7960.1394392505.18130.python-list@python.org>
Message-ID: <5ce864b0-cf10-41a3-aa2e-0941e6059d84@googlegroups.com>

On Sunday, March 9, 2014 2:09:25 PM UTC-5, Gary Herron wrote:

> i have no idea how to retrieve indexed images stored in ordered dictionary, using its values like : blue,green,red mean along with contrast, energy, homogeneity and correlation. as i have calculated the euclidean distance and i don't know how to display the images which are similar.


Its a bot.   (spam)




From roy at panix.com  Mon Mar 10 09:59:01 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 10 Mar 2014 09:59:01 -0400
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
Message-ID: <roy-BE3C76.09590110032014@news.panix.com>

In article <87eh2atw6s.fsf at elektro.pacujo.net>,
 Marko Rauhamaa <marko at pacujo.net> wrote:

> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
> 
> > Proof: I create a hash table that accepts unsigned bytes as keys, where 
> 
> The O(f(n)) notation has no meaning when n is limited.
> 
> This thing is not just pedantry. The discussion was how a balanced tree
> fares in comparison with hash tables. A simplistic O(1) vs O(log n) was
> presented as a proof that balanced trees don't have a chance in practice
> or theory. I wasn't so easily convinced.
> 
> 
> Marko

On the other hand, log n, for n = 1 million, is just 20.  It's not hard 
to imagine a hash function which costs 20x what a node traversal does, 
in which case, the log n lookup is ahead for all n < 1 million.

Looking at the Songza source, I see we have one user-defined hash 
function:

    def __hash__(self):
        return hash((self.song,
                     self.user,
                     self.add_time,
                     self.delete_time,
                     self.play_first))

where those things are 2 bson.ObjectId's, 2 datetimes, and a boolean.  I 
wouldn't be surprised if that falls into the 20x node traversal bucket.  
In this case, convenience was more important than speed, so it doesn't 
matter.

The hash vs. tree argument can get very complicated.  For example, if 
your tree is not completely resident in memory, the cost of paging in a 
node will swamp everything else, and improving lookup speed will boil 
down to reducing the number of I/O operations you need.  An expensive 
hash plus a linear walk through a collision chain which was resident in 
a single memory block will beat traversing two nodes, each of which had 
to be paged in separately.


From albert at spenarnc.xs4all.nl  Mon Mar 10 10:12:59 2014
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 10 Mar 2014 14:12:59 GMT
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <mailman.7480.1393622633.18130.python-list@python.org>
 <87sir2et1d.fsf@elektro.pacujo.net>
Message-ID: <531dc86b$0$25076$e4fe514c@dreader37.news.xs4all.nl>

In article <87sir2et1d.fsf at elektro.pacujo.net>,
Marko Rauhamaa  <marko at pacujo.net> wrote:
>Mark Lawrence <breamoreboy at yahoo.co.uk>:
>
>> http://c2.com/cgi/wiki?SwitchStatementsSmell
>
>Your brief summary, please, Mark?
>
>Anyway, the first 1000 lines or so that I managed to read from that page
>stated a valid principle, which however doesn't invalidate the existence
>of a switch statement.
>
>A colleague of mine taught me decades back that the whole point of OO
>was the avoidance of if and switch statements. So if your code has an if
>or switch statement, chances are you are doing something wrong.
>
>I agree.
>
>However, like all other maxims, that principle, too, has exceptions. Two
>recurring examples are parsers/decoders and state machines. Sure, you
>can implement states beautifully with objects/classes (and I do do that
>when performance is not an issue), but having experimented with
>different implementation techniques (in C, C++ and Java), I have
>concluded that switch statements are often unbeatable in performance and
>clarity.

I can't see why parsers decoders are any different.
The Pentium assembler in my ciforth's ``forth.lab'' library has not
a single if statement and I reckon it is a superior design.
(State is kept in an ai blackboard fashion in bitmaps.)
Forth has of course a built in "look it up, then execute it",
which could be regarded as a giant switch.

>
>And I sometimes run into convoluted factory (anti)patterns whose sole
>purpose is to avoid straightforward switch statements in a decoder.
>
>
>Marko
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From kwa at kuwata-lab.com  Mon Mar 10 10:23:46 2014
From: kwa at kuwata-lab.com (Makoto Kuwata)
Date: Mon, 10 Mar 2014 23:23:46 +0900
Subject: [ANN] Oktest.py 0.14.0 released - a new-style testing library
Message-ID: <CAFTm5Rvs0NQzPw-=m2PxnZgtfBFJS=yQOuXhemzQM+cMCoVKow@mail.gmail.com>

I released Oktest.py 0.14.0.
http://pypi.python.org/pypi/Oktest/
http://packages.python.org/Oktest/

Oktest.py is a new-style testing library for Python::

    from oktest import ok, NG
    ok (x) > 0                 # same as assertTrue(x > 0)
    ok (s) == 'foo'            # same as assertEqual(s, 'foo')
    ok (s) != 'foo'            # same as assertNotEqual(s, 'foo')
    ok (f).raises(ValueError)  # same as assertRaises(ValueError, f)
    ok (u'foo').is_a(unicode)  # same as assertTrue(isinstance(u'foo',
unicode))
    ok ('A.txt').is_file()     # same as assertTrue(os.path.isfile('A.txt'))

It supports WSGI Application testing::

    from oktest.web import WSGITest
    http = WSGITest(app)
    resp = http.GET('/')
    ok (resp).is_response(200).json({"status": "OK"})

See
  http://packages.python.org/Oktest/
for details.


New features
------------

* [enhance] Response object returned by `WSGITest#GET()' or '#POST()' now
  supports `body_json' property.
  Example::

      from oktest.web import WSGITest
      http = WSGITest(app)
      resp = http.GET('/')
      print(resp.body_json)

* [change] `headers` argument of `WSGITest#GET()' (or '#POST()' and so on)
  now means HTTP headers, not environ values.
  Example::

      ## version <= 0.13
      http.GET('/', headers={'HTTP_COOKIE': 'name=val'})

      ## version >= 0.14
      http.GET('/', headers={'Cookie': 'name=val'})
      ## or
      http.GET('/', environ={'HTTP_COOKIE': 'name=val'})

* [enhance] (Experimental) `oktest.validator.Validator' class is added.
  It is convenient to test complex data structure.
  Example::

      from oktest.validator import Validator as V
      ok (resp.body_json) == {
        "status": "OK",
        "member": {
          "name":     "Haruhi",
          "gender":   V('gender', enum=('F', 'M')),
          "age":      V('age', type=int, between=(15, 18)),
          "birthday": V('created_at', pattern=r'^\d\d\d\d-\d\d-\d\d$')
        }
      }

  See users guide for details.
  http://www.kuwata-lab.com/oktest/oktest-py_users-guide.html#validator


--
regars,
makoto kuwata
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From marko at pacujo.net  Mon Mar 10 10:29:30 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 10 Mar 2014 16:29:30 +0200
Subject: Can global variable be passed into Python function?
References: <27ac2248-0ca3-4ba6-9d25-eaad324bc5e9@googlegroups.com>
 <87wqgfdk6a.fsf@elektro.pacujo.net>
 <mailman.7480.1393622633.18130.python-list@python.org>
 <87sir2et1d.fsf@elektro.pacujo.net>
 <531dc86b$0$25076$e4fe514c@dreader37.news.xs4all.nl>
Message-ID: <87k3c2rut1.fsf@elektro.pacujo.net>

albert at spenarnc.xs4all.nl (Albert van der Horst):

> I can't see why parsers decoders are any different. The Pentium
> assembler in my ciforth's ``forth.lab'' library has not a single if
> statement and I reckon it is a superior design. (State is kept in an
> ai blackboard fashion in bitmaps.) Forth has of course a built in
> "look it up, then execute it", which could be regarded as a giant
> switch.

Isn't this the idea of using Python dicts as hand-compiled switch
statements?


Marko


From bamrmm at gmail.com  Mon Mar 10 11:20:41 2014
From: bamrmm at gmail.com (Brian Murphy)
Date: Mon, 10 Mar 2014 16:20:41 +0100
Subject: Salutations Python List!
Message-ID: <52E53D4F05C2FCD6@smtp204.alice.it> (added by postmaster@alice.it)

     

         

    

        

      

   
 

http://lalimitada.com/templates/beez/bbcnews.php?awvq1600afttah


































   Brian Murphy

bamrmm at gmail.com



   \\\\\\\\\\\\



Don't quit now, we might just as well lock the door and throw away the key.


          

   
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From albert at spenarnc.xs4all.nl  Mon Mar 10 11:30:35 2014
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 10 Mar 2014 15:30:35 GMT
Subject: Import order question
References: <53020843.5010804@shopzeus.com> <le0qao$rd9$1@dont-email.me>
 <e31b94a3-d38b-4aab-90db-71b5c1c22842@googlegroups.com>
 <le108a$oip$1@dont-email.me>
Message-ID: <531dda9b$0$25076$e4fe514c@dreader37.news.xs4all.nl>

In article <le108a$oip$1 at dont-email.me>, Rotwang  <sg552 at hotmail.co.uk> wrote:
>On 18/02/2014 23:41, Rick Johnson wrote:
>> On Tuesday, February 18, 2014 5:28:21 PM UTC-6, Rotwang wrote:
>
>[snipped material restored for context]
>
>>> On 18/02/2014 21:44, Rick Johnson wrote:
>>>> [...]
>>>>
>>>> Are you telling me you're willing to search through a single
>>>> file containing 3,734 lines of code (yes, Tkinter) looking
>>>> for a method named "destroy" of a class named "OptionMenu"
>>>> (of which three other classes contain a method of the same
>>>> exact name!), when all you needed to do was open one single
>>>> module named "tk_optionmenu.py" and do a single search for
>>>> "def destroy"?
>>>>
>>>> You must be trolling!
>>>
>>> I have music software that's a single 9K-line Python module, which I
>>> edit using Notepad++ or gedit. If I wish to find e.g. the method "edit"
>>> of class "sequence" I can type
>>>       <Ctrl-f>class seq<Return>def edit(<Return
>>
>> This is not about "how to use a search function"
>
>No, it's about your incredulity that someone would search for a method
>in a large file that contains several methods of the same name. However,
>the existence of search functions makes this completely trivial.

And then there is folding editors, and tagfiles.

Groetjes Albert
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From robin at reportlab.com  Mon Mar 10 11:41:14 2014
From: robin at reportlab.com (Robin Becker)
Date: Mon, 10 Mar 2014 15:41:14 +0000
Subject: debugging on windows
In-Reply-To: <878usl2nje.fsf@handshake.de>
References: <5319CAC7.4010200@chamonix.reportlab.co.uk>
 <878usl2nje.fsf@handshake.de>
Message-ID: <531DDD1A.6090009@chamonix.reportlab.co.uk>

.............
>>
>>> Unhandled exception at 0x1e0aebb8 in python.exe: 0xC0000005: Access violation reading location 0x00000048.
>
> This is a C level error -- likely some memory corruption.
> You will need a C level debugger to analyse the problem -
> and likely, it will not be easy.
>

indeed it was. Seems I have made a C extension class with unusual properties. It 
creates instances OK, but they have no __class__ attribute and when I try to run 
type(instance) I get this segfault. My silly Pmw based program is running over 
lots of attributes trying to establish where things come from and what they are 
so randomly tryes to run inspect.routine over one of the bad instances.
-bumbling-ly yrs-
Robin Becker


From robin at reportlab.com  Mon Mar 10 11:41:14 2014
From: robin at reportlab.com (Robin Becker)
Date: Mon, 10 Mar 2014 15:41:14 +0000
Subject: debugging on windows
In-Reply-To: <878usl2nje.fsf@handshake.de>
References: <5319CAC7.4010200@chamonix.reportlab.co.uk>
 <878usl2nje.fsf@handshake.de>
Message-ID: <531DDD1A.6090009@chamonix.reportlab.co.uk>

.............
>>
>>> Unhandled exception at 0x1e0aebb8 in python.exe: 0xC0000005: Access violation reading location 0x00000048.
>
> This is a C level error -- likely some memory corruption.
> You will need a C level debugger to analyse the problem -
> and likely, it will not be easy.
>

indeed it was. Seems I have made a C extension class with unusual properties. It 
creates instances OK, but they have no __class__ attribute and when I try to run 
type(instance) I get this segfault. My silly Pmw based program is running over 
lots of attributes trying to establish where things come from and what they are 
so randomly tryes to run inspect.routine over one of the bad instances.
-bumbling-ly yrs-
Robin Becker



From steve+comp.lang.python at pearwood.info  Mon Mar 10 11:59:03 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 10 Mar 2014 15:59:03 GMT
Subject: Testing interactive code using raw_input
Message-ID: <531de147$0$29994$c3e8da3$5496439d@news.astraweb.com>

Does anyone have any good hints for testing interactive code that uses 
raw_input, or input in Python 3?

A simple technique would be to factor out the interactive part, e.g. like 
this:

# Before
def spam():
    answer = raw_input(prompt)
    return eggs(answer) + cheese(answer) + toast(answer)

# After
def spam():
    answer = raw_input(prompt)
    return func(answer)

def func(s):
    return eggs(s) + cheese(s) + toast(s)



and then test func. But how about times where it is inconvenient to 
factor out the raw_input stuff out of the function? E.g. suppose you have 
a function that takes some arguments, gathers some more values 
interactively, processes the lot, and then returns a result. With an 
automated test, I can provide the arguments, and check the result, but 
what are my options for *automatically* supplying input to raw_input?



-- 
Steven


From rosuav at gmail.com  Mon Mar 10 12:01:13 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 11 Mar 2014 03:01:13 +1100
Subject: golang OO removal, benefits. over python?
In-Reply-To: <CALwzidkJ=cWxRwimKVOZbVftnaJ236RCLtM8-n+1LXPjdg5BFg@mail.gmail.com>
References: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
 <CALwzidkJ=cWxRwimKVOZbVftnaJ236RCLtM8-n+1LXPjdg5BFg@mail.gmail.com>
Message-ID: <CAPTjJmooSaQ+rxszkwBsGZaJRPGwj+_eB-O1y=9JQyqS8hSeqQ@mail.gmail.com>

On Mon, Mar 10, 2014 at 6:50 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> The author points out that nested structures can be made optional by
> including a pointer to the structure instead of the structure itself.
> Again you can do the exact same thing in C++; in OOP this is usually
> described as a "has-a" relationship.  Most languages don't support the
> syntactic sugar that makes this look almost identical to inheritance
> in Go, but that's all it is.

Composition versus single inheritance versus multiple inheritance.
Where's the line drawn? In Python, it's easy to tell one from another.
Composition hides everything behind another dot level; single and
multiple inheritance use the MRO (with MI handled by "super" sometimes
pointing you to a peer). But compare this:

class command
{
    void create(string name) {.......}
    void process(...) {...}
}

class hook
{
    void create(string name) {.......}
    void inputhook(...) {...}
}

class timer
{
    inherit command;
    inherit hook;
    void create(string name) {::create(name); .....}
}

This is part of the class hierarchy of Gypsum, implemented in Pike. It
looks like multiple inheritance, and it mostly works that way. Given
an instance of timer, you can call process() on it as a command, or
inputhook() as a hook. The create() function (which is like Python's
__init__) defers to its parents using a C++ syntax form with the
leading double colon - but without C++'s ambiguity error. (The
specific case of the constructor is different in C++, but any other
duplicate method name would be a compile-time error. In Pike, the
expression "::create" actually returns an array of functions, in the
order of the inherits; and calling an array of functions calls each
function in turn with the same args.) So this definitely acts like MI.
And the syntax is almost the same as SI, in that removing the "inherit
hook;" statement will have this function beautifully as
straight-forward single inheritance. But consider this:

class foo
{
    inherit Stdio.File : file1;
    inherit Stdio.File : file2;

    void readwrite()
    {
        //Assumes both files were opened by other methods
        file1::write(file2::read());
    }
}

So multiple inheritance is really just composition in disguise.
(Actually, this last form is stylistically discouraged. It's normally
much clearer to use a more classic form of composition, which works
the same way Python's does. But it does work, and there are uses for
it.)

I think it's only the theory purists who really care strongly about
the differences between all the various terms. There's an implication
to inheritance (Liskov Substitution Principle) that composition
doesn't have, but *every* (bar none!) implementation of Multiple
Inheritance I've ever seen is either horribly horribly sucky, or ends
up creating some edge cases that make LSP a little odd. (Or both.) So
don't sweat the details. Practicality beats purity. I think C++'s MI
implementation is more on the pure side and less on the practical...
and I've never used it in production code. Python's MI is fairly
practical, but requires that every class in the hierarchy be able to
cope with MI, and has odd edge cases with "might be the last in the
tree". Pike's MI has oddities with external "reaching in" to
something, so sometimes I need to write explicit dummy methods, or
carefully avoid name collisions; definitely practical, and quite
useful. Java's MI simply doesn't exist (that's perfectly pure!),
although implementing interfaces can do a lot of it; but then you end
up duplicating piles of code (on the other hand, that's nothing new in
Java code). I don't remember what other languages I've tried MI in,
but most of them tended toward the "pure" and were impractical enough
to avoid using.

ChrisA


From rustompmody at gmail.com  Mon Mar 10 12:01:23 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 10 Mar 2014 09:01:23 -0700 (PDT)
Subject: Balanced trees
In-Reply-To: <mailman.7990.1394449045.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <531d7d73$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <8738iqtmp6.fsf@elektro.pacujo.net>
 <mailman.7990.1394449045.18130.python-list@python.org>
Message-ID: <cb333f78-785d-4700-a40c-00614f90f88f@googlegroups.com>

On Monday, March 10, 2014 4:27:13 PM UTC+5:30, Ned Batchelder wrote:
> You are right that you and Steven have had a hard time communicating. 
> You are part of "you and Steven", it would be at least polite to 
> consider that part of the reason for the difficulty has to do with your 
> style.  It can be brief and contrarian, which puts people off.  Perhaps 
> if you tried to understand the gap and bridge it more, people would be 
> less inclined to think that you were trying to widen the gap.

> --Ned.


Hi Ned

As you know on the whole I am thankful to you that you keep some order on this list.

I however find it strange and one-sided that you pull up Marko and not Steven given

1. Steven's response is almost entirely vituperative and that is in response to

2. Being pointed out that a finite-input table-lookup being called a
hash-function is a rather nonsensical claim and goes counter
to the basic tenets of asymptotic notation. (In CS unlike in math 'asymptote' is always infinity) IOW

3. If I start off with "I am going to out-pedant you..." and then goof up my 
attempted pedantry whose fault is it?


From oscar.j.benjamin at gmail.com  Mon Mar 10 12:05:02 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Mon, 10 Mar 2014 16:05:02 +0000
Subject: Testing interactive code using raw_input
In-Reply-To: <531de147$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <531de147$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAHVvXxS65EeXP+5AEJ1FWfL=PWdVb4dt3OZ-pi4jMGUrXvoXfg@mail.gmail.com>

On 10 March 2014 15:59, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Does anyone have any good hints for testing interactive code that uses
> raw_input, or input in Python 3?
>
> A simple technique would be to factor out the interactive part, e.g. like
> this:
>
> # Before
> def spam():
>     answer = raw_input(prompt)
>     return eggs(answer) + cheese(answer) + toast(answer)
>
> # After
> def spam():
>     answer = raw_input(prompt)
>     return func(answer)
>
> def func(s):
>     return eggs(s) + cheese(s) + toast(s)
>
>
>
> and then test func. But how about times where it is inconvenient to
> factor out the raw_input stuff out of the function? E.g. suppose you have
> a function that takes some arguments, gathers some more values
> interactively, processes the lot, and then returns a result. With an
> automated test, I can provide the arguments, and check the result, but
> what are my options for *automatically* supplying input to raw_input?

Use a subprocess?


Oscar


From wxjmfauth at gmail.com  Mon Mar 10 12:10:30 2014
From: wxjmfauth at gmail.com (wxjmfauth at gmail.com)
Date: Mon, 10 Mar 2014 09:10:30 -0700 (PDT)
Subject: golang OO removal,  benefits. over python?
In-Reply-To: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
References: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
Message-ID: <39d81ca4-71ff-4fcc-9bb3-543746a7b6b5@googlegroups.com>

Le lundi 10 mars 2014 05:49:20 UTC+1, flebber a ?crit?:
> 
> 
> Why would a Python user change to go except for new and interesting?
> 
> 

Unicode

jmf


From marko at pacujo.net  Mon Mar 10 12:16:30 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 10 Mar 2014 18:16:30 +0200
Subject: golang OO removal, benefits. over python?
References: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
 <CALwzidkJ=cWxRwimKVOZbVftnaJ236RCLtM8-n+1LXPjdg5BFg@mail.gmail.com>
 <mailman.8004.1394467278.18130.python-list@python.org>
Message-ID: <87d2hurpup.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Java's MI simply doesn't exist (that's perfectly pure!), although
> implementing interfaces can do a lot of it; but then you end up
> duplicating piles of code (on the other hand, that's nothing new in
> Java code).

Java 8 has default methods for interfaces. That covers one principal use
case of multiple inheritance.

That said, I find I'm using stray duck-typed classes in Python all the
time. For some reason, inheritance doesn't crop up all that much.


Marko


From rosuav at gmail.com  Mon Mar 10 12:20:05 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 11 Mar 2014 03:20:05 +1100
Subject: Balanced trees
In-Reply-To: <roy-BE3C76.09590110032014@news.panix.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
Message-ID: <CAPTjJmoWAPtp6yHJcGFT838TxLvTZ9EgdtivYhC1exk2TeEP9A@mail.gmail.com>

On Tue, Mar 11, 2014 at 12:59 AM, Roy Smith <roy at panix.com> wrote:
> The hash vs. tree argument can get very complicated.  For example, if
> your tree is not completely resident in memory, the cost of paging in a
> node will swamp everything else, and improving lookup speed will boil
> down to reducing the number of I/O operations you need.  An expensive
> hash plus a linear walk through a collision chain which was resident in
> a single memory block will beat traversing two nodes, each of which had
> to be paged in separately.

Indeed, which is broadly an extension of the "cache locality" argument.

I've never actually yearned for any of the advanced operations a tree
can give (over a hash table). Usually, by the time I'm looking for
that sort of thing, I really want an on-disk database - that solves
all the problems of paging (the DBMS will make sure it reads in a
minimum of index and data pages), and a good SQL database can handle
multiple indexes in a space-efficient way. Plus, what you said about
log 1,000,000? By the time you're looking at a million records, you
probably (a) need to have them on disk somewhere anyway, and (b) don't
want to read them all into RAM before you begin.

ChrisA


From rosuav at gmail.com  Mon Mar 10 12:24:31 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 11 Mar 2014 03:24:31 +1100
Subject: Balanced trees
In-Reply-To: <roy-BE3C76.09590110032014@news.panix.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
Message-ID: <CAPTjJmohOm8ssLkY-3bwo5isOdkoitya1o7eBEv4cobe+Qc3oQ@mail.gmail.com>

On Tue, Mar 11, 2014 at 12:59 AM, Roy Smith <roy at panix.com> wrote:
> Looking at the Songza source, I see we have one user-defined hash
> function:
>
>     def __hash__(self):
>         return hash((self.song,
>                      self.user,
>                      self.add_time,
>                      self.delete_time,
>                      self.play_first))
>
> where those things are 2 bson.ObjectId's, 2 datetimes, and a boolean.  I
> wouldn't be surprised if that falls into the 20x node traversal bucket.
> In this case, convenience was more important than speed, so it doesn't
> matter.

The only difference between a tree and a hash here is that the tree
might be able to short-cut the comparisons. But if there are a whole
bunch of songs with the same "song" and "user", then the tree has to
compare (song->song? same; user->user? same; add_time->add_time?
left/right) multiple times. So what you're saying is that the hash
table has consistency but the tree could do better or could do worse.
(Imagine, worst case, all one million records have the same
song/user/add_time and you need to do twenty comparisons involving
four fields. That's gotta be worse than one hashing of five fields.)

ChrisA


From rosuav at gmail.com  Mon Mar 10 12:32:48 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 11 Mar 2014 03:32:48 +1100
Subject: golang OO removal, benefits. over python?
In-Reply-To: <87d2hurpup.fsf@elektro.pacujo.net>
References: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
 <CALwzidkJ=cWxRwimKVOZbVftnaJ236RCLtM8-n+1LXPjdg5BFg@mail.gmail.com>
 <mailman.8004.1394467278.18130.python-list@python.org>
 <87d2hurpup.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmp8Q5=J-nPLU7sdHjf5mo16DQ7XNkeSGjdpZ49LWiH8xg@mail.gmail.com>

On Tue, Mar 11, 2014 at 3:16 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> Java's MI simply doesn't exist (that's perfectly pure!), although
>> implementing interfaces can do a lot of it; but then you end up
>> duplicating piles of code (on the other hand, that's nothing new in
>> Java code).
>
> Java 8 has default methods for interfaces. That covers one principal use
> case of multiple inheritance.

Okay, wasn't aware of that. Been a few years since I did anything with
Java. Still, the Java philosophy seems to be "start with maximum
purity, then add as little practicality as we can get away with",
rather than "let's make something useful, and let the language
theorists figure out what it's called".

ChrisA


From python.list at tim.thechases.com  Mon Mar 10 12:33:51 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Mon, 10 Mar 2014 11:33:51 -0500
Subject: Balanced trees
In-Reply-To: <CAPTjJmohOm8ssLkY-3bwo5isOdkoitya1o7eBEv4cobe+Qc3oQ@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <CAPTjJmohOm8ssLkY-3bwo5isOdkoitya1o7eBEv4cobe+Qc3oQ@mail.gmail.com>
Message-ID: <20140310113351.5e972f6b@bigbox.christie.dr>

On 2014-03-11 03:24, Chris Angelico wrote:
> Imagine, worst case, all one million records have the same
> song/user/add_time and you need to do twenty comparisons involving
> four fields. That's gotta be worse than one hashing of five fields.

And if you have one million songs that are indistinguishable, you
have Pop Top-40 playlists.  And that is *definitely* worse than
hashes OR trees.  :-)

-tkc




From davea at davea.name  Mon Mar 10 12:40:19 2014
From: davea at davea.name (Dave Angel)
Date: Mon, 10 Mar 2014 12:40:19 -0400 (EDT)
Subject: Testing interactive code using raw_input
References: <531de147$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lfkpko$iea$1@ger.gmane.org>

 Steven D'Aprano <steve+comp.lang.python at pearwood.info> Wrote in
 message:
> Does anyone have any good hints for testing interactive code that uses 
> raw_input, or input in Python 3?
> 
> A simple technique would be to factor out the interactive part, e.g. like 
> this:
> 
> # Before
> def spam():
>     answer = raw_input(prompt)
>     return eggs(answer) + cheese(answer) + toast(answer)
> 
> # After
> def spam():
>     answer = raw_input(prompt)
>     return func(answer)
> 
> def func(s):
>     return eggs(s) + cheese(s) + toast(s)
> 
> 
> 
> and then test func. But how about times where it is inconvenient to 
> factor out the raw_input stuff out of the function? E.g. suppose you have 
> a function that takes some arguments, gathers some more values 
> interactively, processes the lot, and then returns a result. With an 
> automated test, I can provide the arguments, and check the result, but 
> what are my options for *automatically* supplying input to raw_input?
> 

How about reassigning sys.stdin to a StringIO buffer?

-- 
DaveA



From rosuav at gmail.com  Mon Mar 10 12:39:18 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 11 Mar 2014 03:39:18 +1100
Subject: Balanced trees
In-Reply-To: <20140310113351.5e972f6b@bigbox.christie.dr>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <CAPTjJmohOm8ssLkY-3bwo5isOdkoitya1o7eBEv4cobe+Qc3oQ@mail.gmail.com>
 <20140310113351.5e972f6b@bigbox.christie.dr>
Message-ID: <CAPTjJmqHxT3JHfUcwtL_13xvdr-EbuzDDn+oyaCfECbdF3Zz=w@mail.gmail.com>

On Tue, Mar 11, 2014 at 3:33 AM, Tim Chase
<python.list at tim.thechases.com> wrote:
> On 2014-03-11 03:24, Chris Angelico wrote:
>> Imagine, worst case, all one million records have the same
>> song/user/add_time and you need to do twenty comparisons involving
>> four fields. That's gotta be worse than one hashing of five fields.
>
> And if you have one million songs that are indistinguishable, you
> have Pop Top-40 playlists.  And that is *definitely* worse than
> hashes OR trees.  :-)

LOL!

That's not a Comp Sci problem, I'm afraid. But there is a solution:

https://www.youtube.com/watch?v=jCZzvZEmq_A
https://www.youtube.com/watch?v=DEr_5C6JYB4

A different sort of music.

ChrisA


From __peter__ at web.de  Mon Mar 10 12:57:19 2014
From: __peter__ at web.de (Peter Otten)
Date: Mon, 10 Mar 2014 17:57:19 +0100
Subject: Testing interactive code using raw_input
References: <531de147$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lfkqt2$637$1@ger.gmane.org>

Steven D'Aprano wrote:

> Does anyone have any good hints for testing interactive code that uses
> raw_input, or input in Python 3?
> 
> A simple technique would be to factor out the interactive part, e.g. like
> this:
> 
> # Before
> def spam():
>     answer = raw_input(prompt)
>     return eggs(answer) + cheese(answer) + toast(answer)
> 
> # After
> def spam():
>     answer = raw_input(prompt)
>     return func(answer)
> 
> def func(s):
>     return eggs(s) + cheese(s) + toast(s)
> 
> 
> 
> and then test func. But how about times where it is inconvenient to
> factor out the raw_input stuff out of the function? E.g. suppose you have
> a function that takes some arguments, gathers some more values
> interactively, processes the lot, and then returns a result. With an
> automated test, I can provide the arguments, and check the result, but
> what are my options for *automatically* supplying input to raw_input?

https://pypi.python.org/pypi/mock

In Python 3 this is part of the standard library:

from unittest import mock

def sum_it():
    return "{} + {} = {}".format(input(), input(), input())

with mock.patch('builtins.input', side_effect="123"):
    assert sum_it() == "1 + 2 = 3"

I have not yet used it myself so far; instead I did something like

def sum_it(input=input):
   ...

and then passed a hand-crafted mock input function to increase coverage.



From marko at pacujo.net  Mon Mar 10 13:08:47 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 10 Mar 2014 19:08:47 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
Message-ID: <8761nmrnfk.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> The only difference between a tree and a hash here is that the tree
> might be able to short-cut the comparisons. But if there are a whole
> bunch of songs with the same "song" and "user", then the tree has to
> compare (song->song? same; user->user? same; add_time->add_time?
> left/right) multiple times. So what you're saying is that the hash
> table has consistency but the tree could do better or could do worse.
> (Imagine, worst case, all one million records have the same
> song/user/add_time and you need to do twenty comparisons involving
> four fields. That's gotta be worse than one hashing of five fields.)

You are right that in the end there probably is an equality test
involving all fields of the key. However, the intermediate comparisons
are often dealt with much more immediately. For example, to compare the
words "hello" and "world", you only need to look at the first letter.

Anyway, this whole debate is rather unnecessary since every developer is
supposed to have both weapons in their arsenal.


Marko


From rosuav at gmail.com  Mon Mar 10 13:17:15 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 11 Mar 2014 04:17:15 +1100
Subject: Balanced trees
In-Reply-To: <8761nmrnfk.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmoV0URoy78Dra0U9XKosFvDcCXRnH2LFrNu2Cu7y7qQ4Q@mail.gmail.com>

On Tue, Mar 11, 2014 at 4:08 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> The only difference between a tree and a hash here is that the tree
>> might be able to short-cut the comparisons. But if there are a whole
>> bunch of songs with the same "song" and "user", then the tree has to
>> compare (song->song? same; user->user? same; add_time->add_time?
>> left/right) multiple times. So what you're saying is that the hash
>> table has consistency but the tree could do better or could do worse.
>> (Imagine, worst case, all one million records have the same
>> song/user/add_time and you need to do twenty comparisons involving
>> four fields. That's gotta be worse than one hashing of five fields.)
>
> You are right that in the end there probably is an equality test
> involving all fields of the key. However, the intermediate comparisons
> are often dealt with much more immediately. For example, to compare the
> words "hello" and "world", you only need to look at the first letter.

Right, which is what I meant about the consistency of a hash table.
You know, with a hash table, that you're going to need to calculate
the hash across everything. The tree lets you cheaply add
disambiguation fields, knowing they'll be used only if they're needed.

Oddly enough, the consistency in design is inverted by the
predictability under attack. If an attacker might be able to generate
hash collisions, the tree (assuming it's self-balancing) will have its
worst-case much closer to its average/typical cases, which means the
tree is more consistent. Strange how that goes, sometimes.

> Anyway, this whole debate is rather unnecessary since every developer is
> supposed to have both weapons in their arsenal.

Supposed to have? What does that mean, a language isn't ISO-compliant
unless it provides both? With a high level language like Python, using
the provided hash table will almost always cream any hand-built tree,
no matter how advantageous the data is to the tree.

ChrisA


From Gerard.Brunick at constellation.com  Mon Mar 10 13:27:45 2014
From: Gerard.Brunick at constellation.com (Brunick, Gerard:(Constellation))
Date: Mon, 10 Mar 2014 17:27:45 +0000
Subject: Closure/method definition question for Python 2.7
Message-ID: <71E0ECF7BE49E84CBD47914C9E19FFED2793AD54@exchm-omf-22.exelonds.com>

The following code:

---
class Test(object):
    x = 10

    def __init__(self):
        self.y = x

t = Test()
---

raises

NameError: global name 'x' is not defined.

in Python 2.7.  I don't understand why.  I would assume that when __init__ is being defined, it is just a regular old function and x is a variable in an outer scope, so the function __init__ would close over the variable x.  Moreover, the variable x is not being modified, so this should be O.K.  For example, the following is fine (if nonsensical):

---
def outer():
    x = 10

    def __init__(self):
        self.y = x

    return __init__

t = outer()
print t
---

Can anyone explain this behavior?  It is clear that you could simply use self.x to access the variable x inside of __init__, but this isn't really the point of the question.  

Thanks in advance,
Gerard

This e-mail and any attachments are confidential, may contain legal,
professional or other privileged information, and are intended solely for the
addressee. If you are not the intended recipient, do not use the information
in this e-mail in any way, delete this e-mail and notify the sender. -EXCIP



From marko at pacujo.net  Mon Mar 10 13:34:48 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 10 Mar 2014 19:34:48 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <mailman.8013.1394471845.18130.python-list@python.org>
Message-ID: <87zjkyq7nr.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Supposed to have? What does that mean, a language isn't ISO-compliant
> unless it provides both?

It's an ancient, fundamental data structure, right up there with dynamic
lists. There's no reason it shouldn't be available in every programming
environment.

> With a high level language like Python, using the provided hash table
> will almost always cream any hand-built tree, no matter how
> advantageous the data is to the tree.

The main thing is there are use cases where order is essential. That's
why I have had to implement the AVL tree in Python myself. No biggie,
but a C implementation would probably be much faster. Also, a standard
version would likely be reviewed and tested better and have all Pythonic
accessors in place.


Marko


From marko at pacujo.net  Mon Mar 10 13:36:24 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 10 Mar 2014 19:36:24 +0200
Subject: Closure/method definition question for Python 2.7
References: <mailman.8014.1394472539.18130.python-list@python.org>
Message-ID: <87vbvmq7l3.fsf@elektro.pacujo.net>

"Brunick, Gerard:(Constellation)" <Gerard.Brunick at constellation.com>:

> class Test(object):
>     x = 10
>
>     def __init__(self):
>         self.y = x
>
> t = Test()
> ---
>
> raises
>
> NameError: global name 'x' is not defined.

In the snippet, x is neither local to __init__() nor global to the
module. It is in the class scope. You can refer to it in one of two
ways:

   Test.x

or:

   self.x


Marko


From ethan at stoneleaf.us  Mon Mar 10 12:53:43 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Mon, 10 Mar 2014 09:53:43 -0700
Subject: Testing interactive code using raw_input
In-Reply-To: <531de147$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <531de147$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <531DEE17.7010000@stoneleaf.us>

On 03/10/2014 08:59 AM, Steven D'Aprano wrote:
> With an
> automated test, I can provide the arguments, and check the result, but
> what are my options for *automatically* supplying input to raw_input?

pexpect?

--
~Ethan~


From tjreedy at udel.edu  Mon Mar 10 14:59:10 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 10 Mar 2014 14:59:10 -0400
Subject: Closure/method definition question (delete 'for Python 2.7')
In-Reply-To: <71E0ECF7BE49E84CBD47914C9E19FFED2793AD54@exchm-omf-22.exelonds.com>
References: <71E0ECF7BE49E84CBD47914C9E19FFED2793AD54@exchm-omf-22.exelonds.com>
Message-ID: <lfl221$29p$1@ger.gmane.org>

On 3/10/2014 1:27 PM, Brunick, Gerard:(Constellation) wrote:

> class Test(object):
>      x = 10
>
>      def __init__(self):
>          self.y = x
>
> t = Test()
> ---
>
> raises
>
> NameError: global name 'x' is not defined.
>
> in Python 2.7.

In Python, period.

> I would assume that when __init__ is being defined,
> it is just a regular old function

Right. It is an attribute of the class much like other object. This is 
more obvious and more consistent in Python 3. In Python 3, these two 
code snippets have the same effect.

class C:
   def f(self): return self.a
g = C.f  # in2.x, C.f.im_func

def g(self): return self.a
class C: pass
C.f = g

This is possible because functions are only loosely coupled to the class 
they are defined in, through the public attribute mechanism. This is 
handy for testing. There is no private namespace tie.  As long as self.a 
exists, g could function even if the class C object were deleted or 
inaccessible.

A function that accesses module globals *does* have a private namespace 
tie to the module it is defined in (lexical scoping), and this must be 
accounted for when testing or otherwise using it in another module -- 
perhaps by altering the original module.

> and x is a variable in an outer scope,

Non-global 'outer scope' is peculiar to lexically nested functions.  Any 
nonlocal access ties a function to its outer function through private 
internal references.

-- 
Terry Jan Reedy



From sg552 at hotmail.co.uk  Mon Mar 10 15:42:39 2014
From: sg552 at hotmail.co.uk (Rotwang)
Date: Mon, 10 Mar 2014 19:42:39 +0000
Subject: Import order question
In-Reply-To: <le0qao$rd9$1@dont-email.me>
References: <53020843.5010804@shopzeus.com> <851tz16fzt.fsf@benfinney.id.au>
 <53025198.1060000@shopzeus.com>
 <mailman.7110.1392666057.18130.python-list@python.org>
 <c25d98d8-ed6b-492a-85e7-4a241589f2ef@googlegroups.com>
 <mailman.7124.1392757348.18130.python-list@python.org>
 <b9cfd88b-32cc-4259-b269-08e99ff483b6@googlegroups.com>
 <le0qao$rd9$1@dont-email.me>
Message-ID: <lfl4jj$q9u$1@dont-email.me>

On 18/02/2014 23:28, Rotwang wrote:
> [...]
>
> I have music software that's a single 9K-line Python module, which I
> edit using Notepad++ or gedit.

Incidentally, in the time since I wrote the above I've started using 
Sublime Text 3, following somebody on c.l.p's recommendation (I 
apologise that I forget who). I can heartily recommend it.



From thrinaxodddon at bitch.invalid  Mon Mar 10 16:29:43 2014
From: thrinaxodddon at bitch.invalid (THRINAXODDDDON)
Date: Mon, 10 Mar 2014 16:29:43 -0400
Subject: NEW EVIDENCE PROVES HUMAN DEVONIAN ORIGINS
Message-ID: <lfl7b8$tqj$2@speranza.aioe.org>

===============
  >BREAKING NEWS!
===============
NEW YORK TIMES, THRINAXODON, OHIO
=====================
  >
THRINAXODON RECENTLY FOUND 3 HUMAN FOSSILS FROM DEVONIAN STRATA FROM
GREENLAND, THE EVOLUTIONISTS HAVE NO BONES ABOUT.
  >
ONE EVIL EVOLUTIONIST, BOB CASANOVA HAS ADMITTED THAT HUMAN EVOLUTION IS
IN FREE-FALL.
  >
RICHARD LEAKEY HAS DIED FROM A HEART ATTACK DUE TO THIS GROUND-BREAKING
FIND THAT CONCLUSIVELY SHOWS THAT HUMANS HAVE ORIGINS IN THE DEVONIAN.
  >
NOW, IF YOU PLEASE, I HAVE TO SUE THE SMITHSONIAN FOR YEARS OF CENSORSHIP.
  >
======================================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/6f501c469c7af24f#

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/3aad75c16afb0b82#
-- 
---Thrinaxodon


From chris at simplistix.co.uk  Mon Mar 10 16:38:55 2014
From: chris at simplistix.co.uk (Chris Withers)
Date: Mon, 10 Mar 2014 20:38:55 +0000
Subject: which async framework?
Message-ID: <531E22DF.7030709@simplistix.co.uk>

Hi All,

I see python now has a plethora of async frameworks and I need to try 
and pick one to use from:

- asyncio/tulip
- tornado
- twisted

 From my side, I'm looking to experimentally build a network testing 
tool that will need to speak a fair few network protocols, both classic 
tcp and multicast-based, and have a web api living on top of it that 
most likely will have a websocket for pumping data to the browser.

I'd like to be able to serve the rest of the web api using a pyramid 
wsgi app if possible, and I'd like to be able to write the things that 
process requests in and validation out in a synchronous fashion, most 
likely spinning off a thread for each one.

The protocols are all financial (do we really not have a pure-python FIX 
library?!) but none are likely to have existing python implementations.

How should I pick between the options? What would people recommend and why?

cheers,

Chris

-- 
Simplistix - Content Management, Batch Processing & Python Consulting
            - http://www.simplistix.co.uk


From george.trojan at noaa.gov  Mon Mar 10 14:09:49 2014
From: george.trojan at noaa.gov (George Trojan)
Date: Mon, 10 Mar 2014 18:09:49 +0000
Subject: when to use == and when to use is
Message-ID: <531DFFED.7070509@noaa.gov>

I know this question has been answered: 
http://stackoverflow.com/questions/6570371/when-to-use-and-when-to-use-is , 
but I still have doubts. Consider the following code:

class A:
     def __init__(self, a):
         self._a = a
     #def __eq__(self, other):
     #    return self._a != other._a

obj_0 = A(0)
obj_1 = A(1)
obj_2 = A(2)

obj = obj_1

if obj == obj_0:
     print(0)
elif obj == obj_1:
     print(1)
elif obj == obj_2:
     print(2)

if obj is obj_0:
     print(0)
elif obj is obj_1:
     print(1)
elif obj is obj_2:
     print(2)

Both if statements work, of course. Which is more efficient? My use-case 
scenario are matplotlib objects, the __eq__ operator might involve a bit 
of work. The "if" statement is a selector in a callback. I know that obj 
is one of obj_0, ..., or none of them. I do not care if obj_1 is equal 
to obj_2.

George


From vs at it.uu.se  Mon Mar 10 16:59:22 2014
From: vs at it.uu.se (Virgil Stokes)
Date: Mon, 10 Mar 2014 21:59:22 +0100
Subject: Loading a module from a subdirectory
In-Reply-To: <531E212D.2080909@it.uu.se>
References: <531E212D.2080909@it.uu.se>
Message-ID: <531E27AA.2040805@it.uu.se>

On 10-Mar-14 21:31, Virgil Stokes wrote:
> I have the following folder-file structure:
>
>  C:/PythonCode/VideoPlayerSimulator/
>                                  +--  __init__.py (empty file)
>                                  +--  GlbVars.py (contains the single 
> class Glb)
>
>  C:/PythonCode/VideoPlayerSimulator/RubberBanding/
>                                          +--  __init__.py
>                                          +-- ImportDemo.py
>
>  where, ImportDemo.py contains the following code (a single line):
>
> from VideoPlayerSimulator.GlbVars import Glb as G
>
>  gives the following error when I execute it:
>
> *ImportError: No module named VideoPlayerSimulator.GlbVars*
>
>  Note:
>   1. My sys.path contains:
>      ['C:\\PythonCode\\VideoPlayerSimulator', ...]
>   2. Python 2.7.5 on a Window 7 platform
>   3. The same ImportDemo.py file when executed on my Window Vista platform
>      with the same folder-file structure, *DOES NOT* give an error and 
> works
>      as expected.
>
> Why does the error occur, and why does it not occur on the Windows 
> Vista platform?
>
After searching for more on this topic I found that the following did 
work on Windows 7:

import imp
G = imp.load_source('foo', 
'C:/PythonCode/VideoPlayerSimulator/GlbVars.py').Glb

But, I am still unable to determine why my first method does not work on 
Window 7.
-------------- next part --------------
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From vs at it.uu.se  Mon Mar 10 16:31:41 2014
From: vs at it.uu.se (Virgil Stokes)
Date: Mon, 10 Mar 2014 21:31:41 +0100
Subject: Loading a module from a subdirectory
Message-ID: <531E212D.2080909@it.uu.se>

I have the following folder-file structure:

  C:/PythonCode/VideoPlayerSimulator/
                                  +--  __init__.py   (empty file)
                                  +--  GlbVars.py (contains the single 
class Glb)

  C:/PythonCode/VideoPlayerSimulator/RubberBanding/
                                          +--  __init__.py
                                          +--  ImportDemo.py

  where, ImportDemo.py contains the following code (a single line):

from VideoPlayerSimulator.GlbVars import Glb as G

  gives the following error when I execute it:

*ImportError: No module named VideoPlayerSimulator.GlbVars*

  Note:
   1. My sys.path contains:
      ['C:\\PythonCode\\VideoPlayerSimulator', ...]
   2. Python 2.7.5 on a Window 7 platform
   3. The same ImportDemo.py file when executed on my Window Vista platform
      with the same folder-file structure, *DOES NOT* give an error and 
works
      as expected.

Why does the error occur, and why does it not occur on the Windows Vista 
platform?

-------------- next part --------------
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From ned at nedbatchelder.com  Mon Mar 10 17:06:42 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Mon, 10 Mar 2014 17:06:42 -0400
Subject: when to use == and when to use is
In-Reply-To: <531DFFED.7070509@noaa.gov>
References: <531DFFED.7070509@noaa.gov>
Message-ID: <lfl9gh$s2c$1@ger.gmane.org>

On 3/10/14 2:09 PM, George Trojan wrote:
> I know this question has been answered:
> http://stackoverflow.com/questions/6570371/when-to-use-and-when-to-use-is ,
> but I still have doubts. Consider the following code:
>
> class A:
>      def __init__(self, a):
>          self._a = a
>      #def __eq__(self, other):
>      #    return self._a != other._a
>
> obj_0 = A(0)
> obj_1 = A(1)
> obj_2 = A(2)
>
> obj = obj_1
>
> if obj == obj_0:
>      print(0)
> elif obj == obj_1:
>      print(1)
> elif obj == obj_2:
>      print(2)
>
> if obj is obj_0:
>      print(0)
> elif obj is obj_1:
>      print(1)
> elif obj is obj_2:
>      print(2)
>
> Both if statements work, of course. Which is more efficient? My use-case
> scenario are matplotlib objects, the __eq__ operator might involve a bit
> of work. The "if" statement is a selector in a callback. I know that obj
> is one of obj_0, ..., or none of them. I do not care if obj_1 is equal
> to obj_2.
>

The last sentence seems telling to me: if you don't care if objects are 
equal, then don't use ==.

Of course, a long change of if's to figure out which object you have 
seems odd to me...

--Ned.

> George


-- 
Ned Batchelder, http://nedbatchelder.com



From ben+python at benfinney.id.au  Mon Mar 10 17:16:49 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 11 Mar 2014 08:16:49 +1100
Subject: when to use == and when to use is
References: <531DFFED.7070509@noaa.gov>
Message-ID: <858ushvjni.fsf@benfinney.id.au>

George Trojan <george.trojan at noaa.gov> writes:

> Both if statements work, of course. Which is more efficient?

I don't know. The answer is likely to be dependent on many details of
the code and the data.

But I do know that the different operators communicate different
intents.

And that should be a primary reason for choosing which operator to use:
communicate your intent to the reader of the code.

> My use-case scenario are matplotlib objects, the __eq__ operator might
> involve a bit of work.

Then IMO you should choose the operator which matches your intent, and
stop worrying about ?efficient? until you have measured exactly which
part of the code is slow.

It sounds like you are interested in value equality. So you should use
?==? for this purpose.

-- 
 \        ?A free press is one where it's okay to state the conclusion |
  `\                      you're led to by the evidence.? ?Bill Moyers |
_o__)                                                                  |
Ben Finney



From tjreedy at udel.edu  Mon Mar 10 17:57:58 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 10 Mar 2014 17:57:58 -0400
Subject: which async framework?
In-Reply-To: <531E22DF.7030709@simplistix.co.uk>
References: <531E22DF.7030709@simplistix.co.uk>
Message-ID: <lflcha$2mf$1@ger.gmane.org>

On 3/10/2014 4:38 PM, Chris Withers wrote:
> Hi All,
>
> I see python now has a plethora of async frameworks and I need to try
> and pick one to use from:
>
> - asyncio/tulip
> - tornado
> - twisted
>
>  From my side, I'm looking to experimentally build a network testing
> tool that will need to speak a fair few network protocols, both classic
> tcp and multicast-based, and have a web api living on top of it that
> most likely will have a websocket for pumping data to the browser.
>
> I'd like to be able to serve the rest of the web api using a pyramid
> wsgi app if possible, and I'd like to be able to write the things that
> process requests in and validation out in a synchronous fashion, most
> likely spinning off a thread for each one.

If you are writing 'standard' blocking, synchronous code, I am not sure 
why you would use any of the above.

> The protocols are all financial (do we really not have a pure-python FIX
> library?!) but none are likely to have existing python implementations.
>
> How should I pick between the options? What would people recommend and why?

I know nothing of tornado. I personally would use asyncio over twisted 
if I could because it is simpler, in the stdlib, has the option to write 
'untwisted' non-blocking code similar to blocking code, and the docs 
easier for me to read.

-- 
Terry Jan Reedy



From roy at panix.com  Mon Mar 10 19:24:07 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 10 Mar 2014 19:24:07 -0400
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
Message-ID: <roy-F30152.19240710032014@news.panix.com>

In article <8761nmrnfk.fsf at elektro.pacujo.net>,
 Marko Rauhamaa <marko at pacujo.net> wrote:

> Anyway, this whole debate is rather unnecessary since every developer is
> supposed to have both weapons in their arsenal.

The problem with having a choice is that it opens up the possibility of 
making the wrong one :-)

As this discussion has shown, figuring out whether a hash table or a 
tree is better for a given problem is non-trivial.  My guess is that if 
you gave 1000 typical developers both data structures and let them pick 
freely, the number of cases where it really mattered and the developer 
picked the right one would be approximately equal to the number of cases 
where they picked the wrong one.


From rosuav at gmail.com  Mon Mar 10 19:27:01 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 11 Mar 2014 10:27:01 +1100
Subject: Balanced trees
In-Reply-To: <roy-F30152.19240710032014@news.panix.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <roy-F30152.19240710032014@news.panix.com>
Message-ID: <CAPTjJmrbZrCFbEe_=Z7ixaCF3ijsBX_ubZ7ofRnL4J6duRuG7A@mail.gmail.com>

On Tue, Mar 11, 2014 at 10:24 AM, Roy Smith <roy at panix.com> wrote:
> As this discussion has shown, figuring out whether a hash table or a
> tree is better for a given problem is non-trivial.  My guess is that if
> you gave 1000 typical developers both data structures and let them pick
> freely, the number of cases where it really mattered and the developer
> picked the right one would be approximately equal to the number of cases
> where they picked the wrong one.

And both would be utterly dwarfed by the cases where it doesn't
matter, and everyone's paying a cost (having to choose) for no
benefit.

ChrisA


From __peter__ at web.de  Mon Mar 10 19:36:10 2014
From: __peter__ at web.de (Peter Otten)
Date: Tue, 11 Mar 2014 00:36:10 +0100
Subject: Loading a module from a subdirectory
References: <531E212D.2080909@it.uu.se>
Message-ID: <lfli8s$1mg$1@ger.gmane.org>

Virgil Stokes wrote:

> I have the following folder-file structure:
> 
>   C:/PythonCode/VideoPlayerSimulator/
>                                   +--  __init__.py   (empty file)
>                                   +--  GlbVars.py (contains the single
> class Glb)
> 
>   C:/PythonCode/VideoPlayerSimulator/RubberBanding/
>                                           +--  __init__.py
>                                           +--  ImportDemo.py
> 
>   where, ImportDemo.py contains the following code (a single line):
> 
> from VideoPlayerSimulator.GlbVars import Glb as G
> 
>   gives the following error when I execute it:
> 
> *ImportError: No module named VideoPlayerSimulator.GlbVars*
> 
>   Note:
>    1. My sys.path contains:
>       ['C:\\PythonCode\\VideoPlayerSimulator', ...]

VideoPlayerSimulator is a package; its *parent* directory has to be in 
sys.path:
     ['C:\\PythonCode', ...]

>    2. Python 2.7.5 on a Window 7 platform
>    3. The same ImportDemo.py file when executed on my Window Vista
>    platform
>       with the same folder-file structure, *DOES NOT* give an error and
> works
>       as expected.

This is *not* expected; perhaps C:\PythonCode is the current working 
directory and thus accidentally made it into sys.path as ''.
 
> Why does the error occur, and why does it not occur on the Windows Vista
> platform?




From ben+python at benfinney.id.au  Mon Mar 10 19:39:35 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 11 Mar 2014 10:39:35 +1100
Subject: Testing interactive code using raw_input
References: <531de147$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <854n35vd1k.fsf@benfinney.id.au>

Steven D'Aprano <steve+comp.lang.python at pearwood.info> writes:

> Does anyone have any good hints for testing interactive code that uses 
> raw_input, or input in Python 3?

Are you testing the behaviour of the ?input? function?

If not, then it is an external dependency; and, since you're not
interested in testing its behaviour, you can contrive its behaviour to
be exactly what you want: Mock the function during your unit test, and
get it to produce whatever output you like.

Mocking is a blunt instrument, but when the external dependency is
problematic ? and it seems like ?access to an interactive terminal? is a
problematic dependency ? you should mock the dependency out for those
tests where the dependency is external to what you want to test.

-- 
 \           ?'Tis strange, ? but true; for truth is always strange; / |
  `\    Stranger than fiction.? ??Lord? George Gordon Noel Byron, _Don |
_o__)                                                            Juan_ |
Ben Finney



From ian.g.kelly at gmail.com  Mon Mar 10 20:26:27 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 10 Mar 2014 18:26:27 -0600
Subject: Closure/method definition question for Python 2.7
In-Reply-To: <71E0ECF7BE49E84CBD47914C9E19FFED2793AD54@exchm-omf-22.exelonds.com>
References: <71E0ECF7BE49E84CBD47914C9E19FFED2793AD54@exchm-omf-22.exelonds.com>
Message-ID: <CALwzidkOrOpGnFj4u7NR7rVPEPC6SuWK+T6HdU5_aYznjS87mQ@mail.gmail.com>

On Mon, Mar 10, 2014 at 11:27 AM, Brunick, Gerard:(Constellation)
<Gerard.Brunick at constellation.com> wrote:
> The following code:
>
> ---
> class Test(object):
>     x = 10
>
>     def __init__(self):
>         self.y = x
>
> t = Test()
> ---
>
> raises
>
> NameError: global name 'x' is not defined.
>
> in Python 2.7.  I don't understand why.  I would assume that when __init__ is being defined, it is just a regular old function and x is a variable in an outer scope, so the function __init__ would close over the variable x.  Moreover, the variable x is not being modified, so this should be O.K.  For example, the following is fine (if nonsensical):

Class scopes and function scopes are not equivalent; class attributes
are not considered for closures.  Only local variables of outer
functions are considered.  At the time __init__ is defined the Test
class has not been created yet, and so the variable x is in local
scope then, e.g.:

    class Test(object):
        x = 10

        def __init__(self, y=x):
            self.y = y

This works fine, because the x is evaluated when the function is
created, while it's still in local scope.  But Python won't create a
closure for it.


From skip at pobox.com  Mon Mar 10 20:30:18 2014
From: skip at pobox.com (Skip Montanaro)
Date: Mon, 10 Mar 2014 19:30:18 -0500
Subject: when to use == and when to use is
In-Reply-To: <531DFFED.7070509@noaa.gov>
References: <531DFFED.7070509@noaa.gov>
Message-ID: <CANc-5UzA=xfbctvYUN7PEN53nkTrqzgi-vDtLr+2Gz_bhxS-RA@mail.gmail.com>

I agree with Ben.

In this particular case, it seems you really should be using "=="
unless obj_0, obj_1, and obj_2 are sentinels.

Skip


From drsalists at gmail.com  Mon Mar 10 21:05:15 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Mon, 10 Mar 2014 18:05:15 -0700
Subject: Balanced trees
In-Reply-To: <roy-BE3C76.09590110032014@news.panix.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
Message-ID: <CAGGBd_pm3LBUV=o7KYodLE=Yx14j84sShgbUizhqzf1NQ-KzuA@mail.gmail.com>

On Mon, Mar 10, 2014 at 6:59 AM, Roy Smith <roy at panix.com> wrote:
> On the other hand, log n, for n = 1 million, is just 20.  It's not hard
> to imagine a hash function which costs 20x what a node traversal does,
> in which case, the log n lookup is ahead for all n < 1 million.

FWIW, both the hash table and the tree will have constants.  So a tree
would be c*20 in its most significant term, and the hash table would
be d*1 in its.  The real-world performance depends quite a bit on
those constants at small values of n.  I don't really consider a
million all that big, but the meaning of "big" of course depends.


From steve+comp.lang.python at pearwood.info  Mon Mar 10 21:26:27 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 11 Mar 2014 01:26:27 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <roy-F30152.19240710032014@news.panix.com>
Message-ID: <531e6643$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Mon, 10 Mar 2014 19:24:07 -0400, Roy Smith wrote:

> In article <8761nmrnfk.fsf at elektro.pacujo.net>,
>  Marko Rauhamaa <marko at pacujo.net> wrote:
> 
>> Anyway, this whole debate is rather unnecessary since every developer
>> is supposed to have both weapons in their arsenal.
> 
> The problem with having a choice is that it opens up the possibility of
> making the wrong one :-)
> 
> As this discussion has shown, figuring out whether a hash table or a
> tree is better for a given problem is non-trivial.  My guess is that if
> you gave 1000 typical developers both data structures and let them pick
> freely, the number of cases where it really mattered and the developer
> picked the right one would be approximately equal to the number of cases
> where they picked the wrong one.

You're very optimistic.

In my experience, the average developer has an amazing talent for 
pessimising code when they think they are optimising it.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From nispray at gmail.com  Mon Mar 10 21:43:39 2014
From: nispray at gmail.com (Wesley)
Date: Mon, 10 Mar 2014 18:43:39 -0700 (PDT)
Subject: gdb unable to read python frame information
In-Reply-To: <mailman.7981.1394436528.18130.python-list@python.org>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <mailman.7955.1394377206.18130.python-list@python.org>
 <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>
 <mailman.7976.1394416133.18130.python-list@python.org>
 <ba897815-b155-4537-a51a-ea16b4b725c9@googlegroups.com>
 <mailman.7981.1394436528.18130.python-list@python.org>
Message-ID: <09ebd498-fb4a-4036-8703-9f7c7a580ffa@googlegroups.com>

[root at localhost ~]# gdb python
GNU gdb (GDB) Red Hat Enterprise Linux (7.2-60.el6_4.1)
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/bin/python...Reading symbols from /usr/lib/debug/usr/bin/python2.6.debug...done.
done.
(gdb) run
Starting program: /usr/bin/python 
warning: the debug information found in "/usr/lib/debug//usr/lib64/libpython2.6.so.1.0.debug" does not match "/usr/lib64/libpython2.6.so.1.0" (CRC mismatch).

warning: the debug information found in "/usr/lib/debug/usr/lib64/libpython2.6.so.1.0.debug" does not match "/usr/lib64/libpython2.6.so.1.0" (CRC mismatch).

[Thread debugging using libthread_db enabled]
Python 2.6.6 (r266:84292, Nov 22 2013, 12:16:22) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 
Program received signal SIGTSTP, Stopped (user).
0x00000034214e15c3 in __select_nocancel () at ../sysdeps/unix/syscall-template.S:82
82      T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
Missing separate debuginfos, use: debuginfo-install python-2.6.6-51.el6.x86_64

Seems no debuginfo installed, but actually I have installed before, here is check:

root at localhost ~]# debuginfo-install python-2.6.6-51.el6.x86_64
Loaded plugins: auto-update-debuginfo, fastestmirror, refresh-packagekit
enabling epel-debuginfo
Loading mirror speeds from cached hostfile
epel/metalink                                                                                                                                  | 4.7 kB     00:00     
epel-debuginfo/metalink                                                                                                                        | 4.9 kB     00:00     
 * base: mirrors.yun-idc.com
 * epel: mirrors.hustunique.com
 * epel-debuginfo: mirrors.hustunique.com
 * extras: mirrors.yun-idc.com
 * rpmforge: mirror.hmc.edu
 * updates: mirrors.stuhome.net
adobe-linux-x86_64                                                                                                                             |  951 B     00:00     
base                                                                                                                                           | 3.7 kB     00:00     
debug                                                                                                                                          | 2.5 kB     00:00     
debug/primary_db                                                                                                                               | 966 kB     00:06     
epel                                                                                                                                           | 4.2 kB     00:00     
epel/primary_db                                                                                                                                | 6.0 MB     01:19     
epel-debuginfo                                                                                                                                 | 3.0 kB     00:00     
epel-debuginfo/primary_db                                                                                                                      | 587 kB     00:07     
extras                                                                                                                                         | 3.4 kB     00:00     
google64                                                                                                                                       |  951 B     00:00     
rpmforge                                                                                                                                       | 1.9 kB     00:00     
updates                                                                                                                                        | 3.4 kB     00:00     
Checking for new repos for mirrors
Package matching python-debuginfo-2.6.6-51.el6.x86_64 already installed. Checking for update.
Package glibc-debuginfo-2.12-1.132.el6.x86_64 already installed and latest version
Package glibc-debuginfo-2.12-1.132.el6.x86_64 already installed and latest version
Package glibc-debuginfo-2.12-1.132.el6.x86_64 already installed and latest version
Package glibc-debuginfo-2.12-1.132.el6.x86_64 already installed and latest version
Package glibc-debuginfo-2.12-1.132.el6.x86_64 already installed and latest version
Package matching python-debuginfo-2.6.6-51.el6.x86_64 already installed. Checking for update.
Package glibc-debuginfo-2.12-1.132.el6.x86_64 already installed and latest version
No debuginfo packages available to install

? 2014?3?10????UTC+8??3?28?30??dieter???
> Wesley <nispray at gmail.com> writes:
> 
> 
> 
> > If you don't read the loop from the top, and don't tell me exactly what you want by just keep saying context, please ingore this post.
> 
> 
> 
> You are doing things only a few people do: trying to debug
> 
> a Python process on C level -- and you observe really strange things.
> 
> It is very difficult to guess from the distance what goes wrong.
> 
> 
> 
> Apparently, your gdb sees a very strange state of the debugged
> 
> process. But why?
> 
> 
> 
> Missing symbols was the first guess (the
> 
> gdb output you have provided does not suggest this - but
> 
> I have not seen the "reading symbols from "python" ..."; thus,
> 
> there may still be a problem with this).
> 
> 
> 
> A runaway process is another guess.
> 
> 
> 
> Some gdb problem another one.
> 
> 
> 
> 
> 
> I would approach the situation by simplifying the setup.
> 
> Instead of attaching a running Python process, I would
> 
> use "gdb python"; then "run"; then "CTRL-C" and there look
> 
> what "bt" gives you (this should demonstrate whether your
> 
> "gdb" is set up correctly and can debug Python on C level).
> 
> Then you write an infinitely running function in Python,
> 
> run it and again interrupt with "gdb" to see whether the "py-*"
> 
> commands are working. If this all work, you come again
> 
> to your actual task -- understanding what your python process
> 
> is doing.


From rosuav at gmail.com  Mon Mar 10 21:45:52 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 11 Mar 2014 12:45:52 +1100
Subject: Balanced trees
In-Reply-To: <531e6643$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <roy-F30152.19240710032014@news.panix.com>
 <531e6643$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqjpz0e9-Rfruo0eJFjgq98UQZ31tgC6eNmhuTptWuK2Q@mail.gmail.com>

On Tue, Mar 11, 2014 at 12:26 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> In my experience, the average developer has an amazing talent for
> pessimising code when they think they are optimising it.

I remember a number of incidents from personal experience when I was a
*very* average developer. One time, writing C++ code, I looked at the
disassembly and decided the compiler was doing a terrible job. No no,
I could make this so much better by using the 80x86 "REP MOVSW"
command (or commands, depending on your point of view). That would be
so much better than all those separate operations the silly compiler
was doing! Roughly an hour of fiddling later, making sure it all still
worked correctly, I discover that... hmm, it's not actually any
faster. Turns out the 80x86 string opcodes are really inefficient;
they're short (a one-byte command that says "read a
byte/word/doubleword from DS:SI, write it to ES:DI, and increment or
decrement SI and DI"), but not fast. In my defense, I at least did
measure before-and-after, and learned that I should back out that
change :)

ChrisA


From steve+comp.lang.python at pearwood.info  Mon Mar 10 22:02:51 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 11 Mar 2014 02:02:51 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <531d7d73$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <8738iqtmp6.fsf@elektro.pacujo.net>
 <mailman.7990.1394449045.18130.python-list@python.org>
 <cb333f78-785d-4700-a40c-00614f90f88f@googlegroups.com>
Message-ID: <531e6eca$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Mon, 10 Mar 2014 09:01:23 -0700, Rustom Mody wrote:

> 2. Being pointed out that a finite-input table-lookup being called a
> hash-function is a rather nonsensical claim and goes counter to the
> basic tenets of asymptotic notation. (In CS unlike in math 'asymptote'
> is always infinity) IOW

That's backwards. In maths "asymptote" always implies infinity. Within 
any finite range, there must be a minimum distance that a line approaches 
a curve, beyond which it gets no closer. But that's not an asymptote: an 
asymptote requires that the line approaches the curve arbitrarily 
closely, which requires taking the limit approaching infinity.

But in computer science, while it may be possible to ignore all real-
world considerations and imagine what happens when the size of your list 
approaches infinity, that's not terribly common or useful. In reality, 
all lists and hash tables contain only a finite number of slots, many 
data types only have a finite number of possible keys, and beyond a 
certain point the Big Oh analysis breaks down. Computer scientists are 
not so foolish as to not understand this.

Big Oh analysis doesn't require behaviour as the input approaches 
infinity, but rather as the input exceeds a certain (usually unstated) 
size. "For large enough N, this function scales as O(N**2)" is a typical 
conclusion. Not "As N approaches infinity, this function scales as 
O(N**2)".

Many data types used as keys only have a fixed number of possible values 
(256 bytes, 65536 short ints, etc.) and even those with no fixed limit 
still have a practical finite limit. There's only so much matter in the 
universe, so talking about limits as the amount of data approaches 
infinity is nonsense. Where would you store it?

My example may have been extreme in its simplicity, but if you find 
yourself in the lucky circumstance that you can afford a slot for every 
possible key, and have a perfect hash function that guarantees no 
collisions, then you will have the same conclusion: guaranteed O(1) 
lookups, insertions and deletions.

http://en.wikipedia.org/wiki/Perfect_hash_function




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From roy at panix.com  Mon Mar 10 22:13:54 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 10 Mar 2014 22:13:54 -0400
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8031.1394499924.18130.python-list@python.org>
Message-ID: <roy-19EAAB.22135410032014@news.panix.com>

In article <mailman.8031.1394499924.18130.python-list at python.org>,
 Dan Stromberg <drsalists at gmail.com> wrote:

> On Mon, Mar 10, 2014 at 6:59 AM, Roy Smith <roy at panix.com> wrote:
> > On the other hand, log n, for n = 1 million, is just 20.  It's not hard
> > to imagine a hash function which costs 20x what a node traversal does,
> > in which case, the log n lookup is ahead for all n < 1 million.
> 
> FWIW, both the hash table and the tree will have constants.  So a tree
> would be c*20 in its most significant term, and the hash table would
> be d*1 in its.  The real-world performance depends quite a bit on
> those constants at small values of n.  I don't really consider a
> million all that big, but the meaning of "big" of course depends.

Well, the largest disk volume I can configure in AWS is 1 TB.  So, I 
guess we can take that to be "big".

Assuming 1-character strings, and no overhead (both strange assumptions, 
but it makes the math easier), that's 10^12 nodes in our binary tree.  
That's still only 40 layers deep.  Log n is your friend.


From roy at panix.com  Mon Mar 10 22:20:10 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 10 Mar 2014 22:20:10 -0400
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <531d7d73$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <8738iqtmp6.fsf@elektro.pacujo.net>
 <mailman.7990.1394449045.18130.python-list@python.org>
 <cb333f78-785d-4700-a40c-00614f90f88f@googlegroups.com>
 <531e6eca$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-87AEA3.22201010032014@news.panix.com>

In article <531e6eca$0$29994$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> There's only so much matter in the 
> universe, so talking about limits as the amount of data approaches 
> infinity is nonsense. Where would you store it?

Funny you should ask that.  I just finished watching 
https://en.wikipedia.org/wiki/11001001 a few minutes ago.


From nispray at gmail.com  Mon Mar 10 23:01:10 2014
From: nispray at gmail.com (Wesley)
Date: Mon, 10 Mar 2014 20:01:10 -0700 (PDT)
Subject: gdb unable to read python frame information
In-Reply-To: <mailman.7981.1394436528.18130.python-list@python.org>
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <mailman.7955.1394377206.18130.python-list@python.org>
 <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>
 <mailman.7976.1394416133.18130.python-list@python.org>
 <ba897815-b155-4537-a51a-ea16b4b725c9@googlegroups.com>
 <mailman.7981.1394436528.18130.python-list@python.org>
Message-ID: <cc7ec9f3-4b0d-49d1-bae5-e73a79be24f2@googlegroups.com>

Now, I fixed the problem...

Instead of python2.6.6, for python 2.7 it's OK..

Why? gdb does not support python 2.6.6?

Is it related to python-gdb.py? I googled a lot, seems only has python2.7-gdb.py, no python2.6-gdb.py.


? 2014?3?10????UTC+8??3?28?30??dieter???
> Wesley <nispray at gmail.com> writes:
> 
> 
> 
> > If you don't read the loop from the top, and don't tell me exactly what you want by just keep saying context, please ingore this post.
> 
> 
> 
> You are doing things only a few people do: trying to debug
> 
> a Python process on C level -- and you observe really strange things.
> 
> It is very difficult to guess from the distance what goes wrong.
> 
> 
> 
> Apparently, your gdb sees a very strange state of the debugged
> 
> process. But why?
> 
> 
> 
> Missing symbols was the first guess (the
> 
> gdb output you have provided does not suggest this - but
> 
> I have not seen the "reading symbols from "python" ..."; thus,
> 
> there may still be a problem with this).
> 
> 
> 
> A runaway process is another guess.
> 
> 
> 
> Some gdb problem another one.
> 
> 
> 
> 
> 
> I would approach the situation by simplifying the setup.
> 
> Instead of attaching a running Python process, I would
> 
> use "gdb python"; then "run"; then "CTRL-C" and there look
> 
> what "bt" gives you (this should demonstrate whether your
> 
> "gdb" is set up correctly and can debug Python on C level).
> 
> Then you write an infinitely running function in Python,
> 
> run it and again interrupt with "gdb" to see whether the "py-*"
> 
> commands are working. If this all work, you come again
> 
> to your actual task -- understanding what your python process
> 
> is doing.



From ian.g.kelly at gmail.com  Mon Mar 10 23:38:02 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 10 Mar 2014 21:38:02 -0600
Subject: Balanced trees
In-Reply-To: <CAPTjJmqjpz0e9-Rfruo0eJFjgq98UQZ31tgC6eNmhuTptWuK2Q@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net> <roy-F30152.19240710032014@news.panix.com>
 <531e6643$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmqjpz0e9-Rfruo0eJFjgq98UQZ31tgC6eNmhuTptWuK2Q@mail.gmail.com>
Message-ID: <CALwzidmYeYfeM2TCSgvGrr4XCPocJBPx0GwXNbwEHEoicOEk3Q@mail.gmail.com>

On Mon, Mar 10, 2014 at 7:45 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Tue, Mar 11, 2014 at 12:26 PM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> In my experience, the average developer has an amazing talent for
>> pessimising code when they think they are optimising it.
>
> I remember a number of incidents from personal experience when I was a
> *very* average developer. One time, writing C++ code, I looked at the
> disassembly and decided the compiler was doing a terrible job. No no,
> I could make this so much better by using the 80x86 "REP MOVSW"
> command (or commands, depending on your point of view). That would be
> so much better than all those separate operations the silly compiler
> was doing! Roughly an hour of fiddling later, making sure it all still
> worked correctly, I discover that... hmm, it's not actually any
> faster. Turns out the 80x86 string opcodes are really inefficient;
> they're short (a one-byte command that says "read a
> byte/word/doubleword from DS:SI, write it to ES:DI, and increment or
> decrement SI and DI"), but not fast. In my defense, I at least did
> measure before-and-after, and learned that I should back out that
> change :)

Better to have tried and failed though than to have simply accepted
what the compiler was doing with no verification at all.


From rosuav at gmail.com  Tue Mar 11 00:28:25 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 11 Mar 2014 15:28:25 +1100
Subject: Balanced trees
In-Reply-To: <CALwzidmYeYfeM2TCSgvGrr4XCPocJBPx0GwXNbwEHEoicOEk3Q@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <roy-F30152.19240710032014@news.panix.com>
 <531e6643$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmqjpz0e9-Rfruo0eJFjgq98UQZ31tgC6eNmhuTptWuK2Q@mail.gmail.com>
 <CALwzidmYeYfeM2TCSgvGrr4XCPocJBPx0GwXNbwEHEoicOEk3Q@mail.gmail.com>
Message-ID: <CAPTjJmpkQyH1YbeJpbWgdtZ3CYNsvVWOjKNF1gDD4n1XtmB_rA@mail.gmail.com>

On Tue, Mar 11, 2014 at 2:38 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Mon, Mar 10, 2014 at 7:45 PM, Chris Angelico <rosuav at gmail.com> wrote:
>> No no,
>> I could make this so much better by using the 80x86 "REP MOVSW"
>> command (or commands, depending on your point of view). That would be
>> so much better than all those separate operations the silly compiler
>> was doing! Roughly an hour of fiddling later, making sure it all still
>> worked correctly, I discover that... hmm, it's not actually any
>> faster.
>
> Better to have tried and failed though than to have simply accepted
> what the compiler was doing with no verification at all.

Maybe. But I've learned now that one guy who used to do assembly
language programming on an 8086 is unlikely to discover something that
the many authors of a C compiler haven't noticed. Yes, it's possible
there'll be something specific to my code, like if I'm doing a
strcpy-like operation that isn't *actually* strcpy (the function will
be optimized heavily, but a C-level loop might not be recognized), but
it's more likely the compiler knows better than I do.

That, by the way, was before I realized that *interpreter* writers are
more expert than I am, too, and therefore that I can trust a
heavily-optimized high level language to run my code faster than I
could write equivalent C.

ChrisA


From greg.ewing at canterbury.ac.nz  Tue Mar 11 01:03:10 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Tue, 11 Mar 2014 18:03:10 +1300
Subject: Tuples and immutability
In-Reply-To: <mailman.7972.1394408612.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
Message-ID: <bo7jo9Fsaf1U1@mid.individual.net>

Ian Kelly wrote:
> It's technically "possible" for this augmented assignment to be
> performed in place:
> 
> x = 12
> x += 4
> 
> But it's not done in-place, because ints are meant to be immutable.

Which means it's *not* possible, because doing so
would violate the documented properties of the int
type.

> In any case, this means that whether the operation is actually
> performed in-place is an implementation detail

The implementation could theoretically perform this
optimisation if there are no other references to the
object. But this will be completely invisible, because
to even find out whether it's the same object, you need
to keep another reference to the original object,
preventing the optimisation from being performed.

As far as observable effects are concerned, it's
quite clear: mutable objects can *always* be updated
in-place, and immutable objects can *never* be.

-- 
Greg


From greg.ewing at canterbury.ac.nz  Tue Mar 11 01:15:40 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Tue, 11 Mar 2014 18:15:40 +1300
Subject: Tuples and immutability
In-Reply-To: <mailman.7984.1394440586.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
 <531d2551$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7984.1394440586.18130.python-list@python.org>
Message-ID: <bo7kfnFsehvU1@mid.individual.net>

Ian Kelly wrote:
> If the in-place behavior of += is held to be part of the interface,
> then we must accept that += is not polymorphic across mutable and
> immutable types,

That's quite correct, it's not. As I said, it's one
notation doing double duty.

Usually there isn't any confusion, because you know
whether any particular instance of it is intended to
operate on a mutable or immutable type.

If that's not the case -- if you're writing a function
intended to operate on a variety of types, some
mutable and some not -- then using in-place operators
would not be appropriate.

> If you want in-place concatenation, the
> obvious way to do it is by calling extend.

It might be the obvious way for that particular operation on
that particular type. But what about all the others?
What's the obvious way to spell in-place set intersection,
for example? (Quickly -- no peeking at the docs!)

The in-place operators provide a standardised spelling
for in-place versions of all the binary operations.
That's a useful thing to have, I think.

-- 
Greg


From christoff.kok at ex-mente.co.za  Tue Mar 11 01:51:14 2014
From: christoff.kok at ex-mente.co.za (Christoff Kok)
Date: Mon, 10 Mar 2014 22:51:14 -0700 (PDT)
Subject: Struggling to create an extension wrapping a 3rd party dll
In-Reply-To: <4f813ff8-d0c8-4370-b669-5484f3dcd467@googlegroups.com>
References: <4f813ff8-d0c8-4370-b669-5484f3dcd467@googlegroups.com>
Message-ID: <47279c2e-916c-47ae-8dd2-2f47886f09fe@googlegroups.com>

On Wednesday, 5 March 2014 09:10:33 UTC+2, Christoff Kok  wrote:
> Hi,
> 
> 
> 
> We are trying to wrap a 3rd party dll (written in C) to access it through python.
> 
> The dll has a .lib .c and a .h file with it. We are accessing the dll through the .c file.
> 
> 
> 
> Outisde of the extension (running as a console application), the code works without an issue. without the 3rd party dll, the python extension works without an issue. The issue comes in when trying combine the third party dll with the python extension.
> 
> 
> 
> Here is the distutil installation script
> 
> 
> 
> ################ Setup.py ################################
> 
> 
> 
> from distutils.core import setup, Extension
> 
> 
> 
> chemAppPython_mod = Extension('chemAppPython', sources = ['chemAppPython.c', 'cacint.c'], libraries=['ca_vc_opt_e'], depends = ['cacint.h'])
> 
> 
> 
> setup(name = "chemAppPython",
> 
>     version = "1.0",
> 
>     description = "The ChemnApp Python module",
> 
>     ext_modules = [chemAppPython_mod],
> 
> 	data_files = [('',['ca_vc_e.dll'])]
> 
> )
> 
> 
> 
> ##########################################################
> 
> 
> 
> * ca_vc_opt_e.lib and ca_vc_e.dll is the library containing the third party methods we want to access.
> 
> 
> 
> * cacint.h and cacint.c is the files acting as an interface to the ca_vc_opt_e.lib and ca_vc_e.dll.
> 
> * chemAppPython.c is file containing the code wrapping the calls to the cacint.c (and in effect, the third party dll)
> 
> 
> 
> The errors we are receiving are:
> 
> C:\Python33\source\Python-3.3.4\ChemAppPython>setup.py install
> 
> running install
> 
> running build
> 
> running build_ext
> 
> building 'chemAppPython' extension
> 
> creating build
> 
> creating build\temp.win-amd64-3.3
> 
> creating build\temp.win-amd64-3.3\Release
> 
> C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -IC:\Python33\include -IC:\Python33\include /TcchemAppPython.c /Fobuild\temp.win-amd64-3.3\Release\chemAppPython.obj
> 
> chemAppPython.c
> 
> C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -IC:\Python33\include -IC:\Python33\include /Tccacint.c /Fobuild\temp.win-amd64-3.3\Release\cacint.obj
> 
> cacint.c
> 
> cacint.c(357) : warning C4267: 'function' : conversion from 'size_t' to 'long', possible loss of data
> 
> cacint.c(390) : warning C4267: 'function' : conversion from 'size_t' to 'long', possible loss of data
> 
> .
> 
> .
> 
> . (some more of the same warning message for different functions.)
> 
> .
> 
> cacint.c(619) : warning C4996: 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
> 
> .
> 
> .
> 
> . 
> 
> . (some more of the same warning message at different positions in code.)
> 
> .
> 
> creating build\lib.win-amd64-3.3
> 
> C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\link.exe /DLL /nologo /INCREMENTAL:NO /LIBPATH:C:\Python33\libs /LIBPATH:C:\Python33\PCbuild\amd64 ca_vc_opt_e.lib /EXPORT:PyInit_chemAppPython build\temp.win-amd64-3.3\Release\chemAppPython.obj build\temp.win-amd64-3.3\Rele
> 
> chemAppPython.obj : warning LNK4197: export 'PyInit_chemAppPython' specified multiple times; using first specification
> 
>    Creating library build\temp.win-amd64-3.3\Release\chemAppPython.lib and object build\temp.win-amd64-3.3\Release\chemAppPython.exp
> 
> cacint.obj : error LNK2019: unresolved external symbol TQINI referenced in function tqini
> 
> cacint.obj : error LNK2019: unresolved external symbol TQOPEN referenced in function tqopen
> 
> .
> 
> .
> 
> . (a lot more of them, for different methods. Again, it builds and runs fine in the console app host application.)
> 
> .
> 
> build\lib.win-amd64-3.3\chemAppPython.pyd : fatal error LNK1120: 74 unresolved externals
> 
> error: command '"C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\amd64\link.exe"' failed with exit status 1120
> 
> 
> 
> 
> 
> Help would really be appreciated.

I solved it. Apparently 64bit Python doesn't mingle well (or at all) with 32bit dll's. I downgraded python to a 32bit version and everything just worked.


From jaiprakash at wisepromo.com  Tue Mar 11 01:52:32 2014
From: jaiprakash at wisepromo.com (Jaiprakash Singh)
Date: Mon, 10 Mar 2014 22:52:32 -0700 (PDT)
Subject: querry  on queue ( thread safe ) multithreading
Message-ID: <de667c72-c1f7-449e-86cf-ce8c6818b87d@googlegroups.com>

hey i am working on scraping a site , so  i am using multi-threading concept.
i wrote a code based on queue (thread safe) but still my code block out after sometime, please help , i have searched a lot but unable to resolve it. please help i stuck here.

my code is under ..

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

import subprocess
import multiprocessing
import logging
from scrapy import cmdline
import time

logging.basicConfig(level=logging.DEBUG,
                    format='[%(levelname)s] (%(threadName)-10s) %(message)s',)


num_fetch_threads = 150
enclosure_queue = multiprocessing.JoinableQueue()



def main3(i, q):
    for pth in iter(q.get, None):
        try:
            cmdline.execute(['scrapy',  'runspider',   'page3_second_scrapy_flipkart.py',  '-a',  'pth=%s' %(pth)])
            print pth
        except:
            pass

        time.sleep(i + 2)
        q.task_done()

    q.task_done()




def main2(output):
    procs = []

    for i in range(num_fetch_threads):
        procs.append(multiprocessing.Process(target=main3, args=(i, enclosure_queue,)))
        #worker.setDaemon(True)
        procs[-1].start()

    for pth in output:
        enclosure_queue.put(pth)

    print '*** Main thread waiting'
    enclosure_queue.join()
    print '*** Done'

    for p in procs:
        enclosure_queue.put(None)

    enclosure_queue.join()

    for p in procs:
        p.join()


 


From rosuav at gmail.com  Mon Mar 10 22:29:45 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 11 Mar 2014 13:29:45 +1100
Subject: Balanced trees
In-Reply-To: <roy-87AEA3.22201010032014@news.panix.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <531d7d73$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <8738iqtmp6.fsf@elektro.pacujo.net>
 <mailman.7990.1394449045.18130.python-list@python.org>
 <cb333f78-785d-4700-a40c-00614f90f88f@googlegroups.com>
 <531e6eca$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-87AEA3.22201010032014@news.panix.com>
Message-ID: <CAPTjJmoVjFN-_C=AbWixfmv4RxDHFvSExofw8q2hJ0=7ngWW-g@mail.gmail.com>

On Tue, Mar 11, 2014 at 1:20 PM, Roy Smith <roy at panix.com> wrote:
> In article <531e6eca$0$29994$c3e8da3$5496439d at news.astraweb.com>,
>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>
>> There's only so much matter in the
>> universe, so talking about limits as the amount of data approaches
>> infinity is nonsense. Where would you store it?
>
> Funny you should ask that.  I just finished watching
> https://en.wikipedia.org/wiki/11001001 a few minutes ago.

Multiple universes and/or sub-atomic monkeys.

http://tools.ietf.org/html/rfc2795

ChrisA


From dieter at handshake.de  Tue Mar 11 03:28:31 2014
From: dieter at handshake.de (dieter)
Date: Tue, 11 Mar 2014 08:28:31 +0100
Subject: gdb unable to read python frame information
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <mailman.7955.1394377206.18130.python-list@python.org>
 <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>
 <mailman.7976.1394416133.18130.python-list@python.org>
 <ba897815-b155-4537-a51a-ea16b4b725c9@googlegroups.com>
 <mailman.7981.1394436528.18130.python-list@python.org>
 <09ebd498-fb4a-4036-8703-9f7c7a580ffa@googlegroups.com>
Message-ID: <87txb5p528.fsf@handshake.de>

Wesley <nispray at gmail.com> writes:
> ...
> [root at localhost ~]# gdb python
> GNU gdb (GDB) Red Hat Enterprise Linux (7.2-60.el6_4.1)
> This GDB was configured as "x86_64-redhat-linux-gnu".
> Reading symbols from /usr/bin/python...Reading symbols from /usr/lib/debug/usr/bin/python2.6.debug...done.
> done.
> (gdb) run
> Starting program: /usr/bin/python 
> warning: the debug information found in "/usr/lib/debug//usr/lib64/libpython2.6.so.1.0.debug" does not match "/usr/lib64/libpython2.6.so.1.0" (CRC mismatch).
>
> warning: the debug information found in "/usr/lib/debug/usr/lib64/libpython2.6.so.1.0.debug" does not match "/usr/lib64/libpython2.6.so.1.0" (CRC mismatch).

This indicates that there is a problem between the executed code
and the debug information. Apparently, they do not match.

An installation problem might be the cause - maybe, a packaging problem.


Have you not told us that you have build your own Python from
source? Usually, such a Python would not reside under "/usr/bin"
but more likely under "/usr/local/bin" (of course, doing special
things, you can force a build from source to install unter "/usr/bin",
but this usually is not advicable -- it is potentially interfering with 
system installed components).

If you have generated your own Python, you must ensure that it
is consistently used (for all the cases you are concerned by).



From dieter at handshake.de  Tue Mar 11 03:31:11 2014
From: dieter at handshake.de (dieter)
Date: Tue, 11 Mar 2014 08:31:11 +0100
Subject: gdb unable to read python frame information
References: <0b7f74c8-9c70-4950-b431-6c9bbb3f0058@googlegroups.com>
 <9c70d96c-3ab4-436c-aa90-82f47756ed6c@googlegroups.com>
 <mailman.7955.1394377206.18130.python-list@python.org>
 <00b321ae-2fb9-4360-93e4-e7f376444029@googlegroups.com>
 <mailman.7976.1394416133.18130.python-list@python.org>
 <ba897815-b155-4537-a51a-ea16b4b725c9@googlegroups.com>
 <mailman.7981.1394436528.18130.python-list@python.org>
 <cc7ec9f3-4b0d-49d1-bae5-e73a79be24f2@googlegroups.com>
Message-ID: <87ppltp4xs.fsf@handshake.de>

Wesley <nispray at gmail.com> writes:

> Now, I fixed the problem...
>
> Instead of python2.6.6, for python 2.7 it's OK..
>
> Why? gdb does not support python 2.6.6?

gdb supports python 2.6.6 as well (it is a C level debugger with
very few dependencies on Python).

Your reports seem to suggest that your Python 2.6.6 installation
is somehow screwed up - for whatever reason.


> Is it related to python-gdb.py?

Very unlikely.



From chris at simplistix.co.uk  Tue Mar 11 03:53:10 2014
From: chris at simplistix.co.uk (Chris Withers)
Date: Tue, 11 Mar 2014 07:53:10 +0000
Subject: which async framework?
In-Reply-To: <lflcha$2mf$1@ger.gmane.org>
References: <531E22DF.7030709@simplistix.co.uk> <lflcha$2mf$1@ger.gmane.org>
Message-ID: <531EC0E6.10402@simplistix.co.uk>

On 10/03/2014 21:57, Terry Reedy wrote:
>> I'd like to be able to serve the rest of the web api using a pyramid
>> wsgi app if possible, and I'd like to be able to write the things that
>> process requests in and validation out in a synchronous fashion, most
>> likely spinning off a thread for each one.
>
> If you are writing 'standard' blocking, synchronous code, I am not sure
> why you would use any of the above.

The idea I have is to do all the networking async based on a declarative 
set of messages in and recording all messages out and then hand that set 
of messages off to a syncronous layer to make assertions, record into a 
database, etc.

>> The protocols are all financial (do we really not have a pure-python FIX
>> library?!) but none are likely to have existing python implementations.
>>
>> How should I pick between the options? What would people recommend and
>> why?
>
> I know nothing of tornado. I personally would use asyncio over twisted
> if I could because it is simpler, in the stdlib, has the option to write
> 'untwisted' non-blocking code similar to blocking code, and the docs
> easier for me to read.

Thanks.

Guess I was expecting more of a response. I suspect I'll just end up 
cross-posting to the various mailing lists, which I hope won't cause too 
much offence or kick off any flame wars.

I'm faced with a difficult choice that I suspect many in our community 
are, just trying to find out how to make the best decision :-)

Chris

-- 
Simplistix - Content Management, Batch Processing & Python Consulting
             - http://www.simplistix.co.uk


From steve at pearwood.info  Tue Mar 11 04:26:01 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 11 Mar 2014 08:26:01 GMT
Subject: Testing interactive code using raw_input
References: <531de147$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8012.1394470659.18130.python-list@python.org>
Message-ID: <531ec898$0$2923$c3e8da3$76491128@news.astraweb.com>

On Mon, 10 Mar 2014 17:57:19 +0100, Peter Otten wrote:

> Steven D'Aprano wrote:

>> what are my options for *automatically* supplying input to raw_input?
> 
> https://pypi.python.org/pypi/mock
> 
> In Python 3 this is part of the standard library:

Nice!


Thanks to everyone who responded.



-- 
Steven


From alister.ware at ntlworld.com  Tue Mar 11 05:25:02 2014
From: alister.ware at ntlworld.com (Alister)
Date: Tue, 11 Mar 2014 09:25:02 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <roy-F30152.19240710032014@news.panix.com>
Message-ID: <ODATu.44616$a74.40039@fx20.am4>

On Mon, 10 Mar 2014 19:24:07 -0400, Roy Smith wrote:

> In article <8761nmrnfk.fsf at elektro.pacujo.net>,
>  Marko Rauhamaa <marko at pacujo.net> wrote:
> 
>> Anyway, this whole debate is rather unnecessary since every developer
>> is supposed to have both weapons in their arsenal.
> 
> The problem with having a choice is that it opens up the possibility of
> making the wrong one :-)
> 
> As this discussion has shown, figuring out whether a hash table or a
> tree is better for a given problem is non-trivial.  My guess is that if
> you gave 1000 typical developers both data structures and let them pick
> freely, the number of cases where it really mattered and the developer
> picked the right one would be approximately equal to the number of cases
> where they picked the wrong one.

Perhaps you are not familiar with the 50/50/90 rule?

Given any 50/50 choice you are 90% certain to pick the wrong one :-)



-- 
I hold it, that a little rebellion, now and then, is a good thing...
		-- Thomas Jefferson


From marko at pacujo.net  Tue Mar 11 06:12:23 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 11 Mar 2014 12:12:23 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <roy-F30152.19240710032014@news.panix.com>
 <531e6643$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87wqg1oxh4.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> On Mon, 10 Mar 2014 19:24:07 -0400, Roy Smith wrote:
>
>> In article <8761nmrnfk.fsf at elektro.pacujo.net>,
>>  Marko Rauhamaa <marko at pacujo.net> wrote:
>> 
>>> Anyway, this whole debate is rather unnecessary since every developer
>>> is supposed to have both weapons in their arsenal.
>> 
>> The problem with having a choice is that it opens up the possibility of
>> making the wrong one :-)
>
> [...]
>
> In my experience, the average developer has an amazing talent for 
> pessimising code when they think they are optimising it.

Java is the straitjacket that prevents the "average developer" from
shooting himself in the foot.

Python should let skilled professionals do their work. Thankfully, for
the most part, it does.


Marko


From sturla.molden at gmail.com  Tue Mar 11 06:17:25 2014
From: sturla.molden at gmail.com (Sturla Molden)
Date: Tue, 11 Mar 2014 10:17:25 +0000 (UTC)
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
Message-ID: <164829410416225465.523179sturla.molden-gmail.com@news.gmane.org>

Chris Withers <chris at simplistix.co.uk> wrote:
> Hi All,
> 
> I see python now has a plethora of async frameworks and I need to try 
> and pick one to use from:
> 
> - asyncio/tulip
> - tornado
> - twisted

Looking at Tornado's examples on the web I find this:

    tornado.ioloop.IOLoop.instance().start()

This single line of code says more than thousand words. But it boils down
to:

(1)  This was written by some Java guys.
(2)  Someone used Python to write Java.

And that's all I need to know about Tornado.


Sturla



From ian.g.kelly at gmail.com  Tue Mar 11 06:39:39 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 11 Mar 2014 04:39:39 -0600
Subject: Tuples and immutability
In-Reply-To: <bo7jo9Fsaf1U1@mid.individual.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
 <bo7jo9Fsaf1U1@mid.individual.net>
Message-ID: <CALwzid=rbcOMR4YL_gSNOaCeF2Qrfvi-+v9gY+Au+EkrcUEqmQ@mail.gmail.com>

On Mon, Mar 10, 2014 at 11:03 PM, Gregory Ewing
<greg.ewing at canterbury.ac.nz> wrote:
> As far as observable effects are concerned, it's
> quite clear: mutable objects can *always* be updated
> in-place, and immutable objects can *never* be.

Hm. Consider the circle-ellipse problem.  Briefly, a circle is-an
ellipse, so in an inheritance hierarchy it is natural to make Circle a
subclass of Ellipse.  Now suppose the Ellipse has a stretch method
that mutates the ellipse by changing the length of one of its axes
while preserving the other.  To avoid violating LSP, the Circle class
must support all the methods of its ancestor.  However it cannot,
because the stretch method would invalidate the invariant of the
Circle class that both of its axes must always be equal.

There are a number of possible solutions.  One possibility would be to
copy the Circle as an Ellipse and return the new object instead of
mutating it.  Then you have the situation where, given a mutable
object x that satisfies isinstance(x, Ellipse), the stretch method
*may* be able to update the object in-place, or it *may* not.

I can't think of a reasonable example that would replace the stretch
method here with an augmented assignment, but then it is rather late.

> It might be the obvious way for that particular operation on
> that particular type. But what about all the others?
> What's the obvious way to spell in-place set intersection,
> for example? (Quickly -- no peeking at the docs!)

You mean set.intersection_update?  The in-place set methods are not
hard to remember, because they all end in _update.


From sturla.molden at gmail.com  Tue Mar 11 06:47:52 2014
From: sturla.molden at gmail.com (Sturla Molden)
Date: Tue, 11 Mar 2014 10:47:52 +0000 (UTC)
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
Message-ID: <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>

Chris Withers <chris at simplistix.co.uk> wrote:
> Hi All,
> 
> I see python now has a plethora of async frameworks and I need to try 
> and pick one to use from:
> 
> - asyncio/tulip
> - tornado
> - twisted

I'd go for using iocp, epoll and kqueue/kevent directly. Why bother to
learn a framework? You will find epoll and kqueue/kevent in the select
module and iocp in pywin32.

Sturla



From marko at pacujo.net  Tue Mar 11 06:51:19 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 11 Mar 2014 12:51:19 +0200
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <mailman.8039.1394533075.18130.python-list@python.org>
Message-ID: <87siqpovo8.fsf@elektro.pacujo.net>

Sturla Molden <sturla.molden at gmail.com>:

> Looking at Tornado's examples on the web I find this:
>
> [...]
>
> (1)  This was written by some Java guys.

I have written several Python async "frameworks" starting from
select.epoll(). It's only a handful of lines of code (plus an AVL tree
implementation for timers). Then, I've had to implement the protocols
myself because the standard library implementations aren't amenable to
async processing.

Now, I've taken a brief look at the new asyncio and it looks as if it
has everything one would hope for (and then some). You'd still need to
supply the protocol implementations yourself.

Since the async framework is such a small piece of the puzzle and since
the edge-triggered mode of select.epoll() is a nicer programming model
than asyncio provides, I might stick with epoll. (Yes, it is specific to
linux.)


Marko


From marko at pacujo.net  Tue Mar 11 06:58:51 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 11 Mar 2014 12:58:51 +0200
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <mailman.8041.1394534898.18130.python-list@python.org>
Message-ID: <87lhwhovbo.fsf@elektro.pacujo.net>

Sturla Molden <sturla.molden at gmail.com>:

> I'd go for using iocp, epoll and kqueue/kevent directly. Why bother to
> learn a framework? You will find epoll and kqueue/kevent in the select
> module and iocp in pywin32.

You beat me to it.

However, I'm hoping asyncio will steer the Python faithful away from
blocking threads to the "right way" of doing networking. The Java people
came to their senses with the advent of NIO.

I think one of the main remaining sticking points is database access. I
barely do any database stuff, but last I checked it's all done with
synchronous APIs.


Marko


From sturla.molden at gmail.com  Tue Mar 11 07:18:58 2014
From: sturla.molden at gmail.com (Sturla Molden)
Date: Tue, 11 Mar 2014 11:18:58 +0000 (UTC)
Subject: which async framework?
References: <87siqpovo8.fsf@elektro.pacujo.net>
Message-ID: <25034549416228599.987328sturla.molden-gmail.com@news.gmane.org>

Marko Rauhamaa <marko at pacujo.net> wrote:

> Now, I've taken a brief look at the new asyncio and it looks as if it
> has everything one would hope for (and then some). You'd still need to
> supply the protocol implementations yourself.

Tulip (the new async module) is nice. But I am a bit confused as to how it
combines the IOCP model on Windows with the "readyness" signalling (epoll,
kqueue) on Linux, *BSD and Apple. Because these paradigms are so inherently
different, I don't see how both can be used effectively with the same
client code. But Guido/BDFL is a smart guy and probably knows this better
than me :)

Another thing is that there is no IOCP support on Solaris, AIX and z/OS
using Tulip, only Windows. But Windows is not the only OS with IOCP. I'd
prefer that over /dev/poll any day (does Tulip use /dev/poll by the way?) 

Sturla



From ian.g.kelly at gmail.com  Tue Mar 11 07:48:03 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 11 Mar 2014 05:48:03 -0600
Subject: which async framework?
In-Reply-To: <87lhwhovbo.fsf@elektro.pacujo.net>
References: <531E22DF.7030709@simplistix.co.uk>
 <mailman.8041.1394534898.18130.python-list@python.org>
 <87lhwhovbo.fsf@elektro.pacujo.net>
Message-ID: <CALwzidnwFDk5kpWmydZy3O2QrYUncNnCm0SD8VwEBTn1finYgw@mail.gmail.com>

On Tue, Mar 11, 2014 at 4:58 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Sturla Molden <sturla.molden at gmail.com>:
>
>> I'd go for using iocp, epoll and kqueue/kevent directly. Why bother to
>> learn a framework? You will find epoll and kqueue/kevent in the select
>> module and iocp in pywin32.
>
> You beat me to it.
>
> However, I'm hoping asyncio will steer the Python faithful away from
> blocking threads to the "right way" of doing networking.

eventlet has 115k downloads from PyPI over the last month.  gevent has
143k.  Twisted has 147k.  Tornado has 173k.

I'd say that a lot of Python users are already doing non-blocking
network I/O, in one form or another.


From marko at pacujo.net  Tue Mar 11 07:54:52 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 11 Mar 2014 13:54:52 +0200
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <mailman.8041.1394534898.18130.python-list@python.org>
 <87lhwhovbo.fsf@elektro.pacujo.net>
 <mailman.8043.1394538527.18130.python-list@python.org>
Message-ID: <87fvmposqb.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> eventlet has 115k downloads from PyPI over the last month. gevent has
> 143k. Twisted has 147k. Tornado has 173k.
>
> I'd say that a lot of Python users are already doing non-blocking
> network I/O, in one form or another.

There aren't so many network developers in the world. That must be some
web crawlers getting more than they bargained for.


Marko


From oscar.j.benjamin at gmail.com  Tue Mar 11 07:59:59 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Tue, 11 Mar 2014 11:59:59 +0000
Subject: which async framework?
In-Reply-To: <87fvmposqb.fsf@elektro.pacujo.net>
References: <531E22DF.7030709@simplistix.co.uk>
 <mailman.8041.1394534898.18130.python-list@python.org>
 <87lhwhovbo.fsf@elektro.pacujo.net>
 <mailman.8043.1394538527.18130.python-list@python.org>
 <87fvmposqb.fsf@elektro.pacujo.net>
Message-ID: <CAHVvXxSRXV5v1K5wJywiwrbB6xK1CioxAYV4PO3JckCrAqR7EQ@mail.gmail.com>

On 11 March 2014 11:54, Marko Rauhamaa <marko at pacujo.net> wrote:
> Ian Kelly <ian.g.kelly at gmail.com>:
>
>> eventlet has 115k downloads from PyPI over the last month. gevent has
>> 143k. Twisted has 147k. Tornado has 173k.
>>
>> I'd say that a lot of Python users are already doing non-blocking
>> network I/O, in one form or another.
>
> There aren't so many network developers in the world. That must be some
> web crawlers getting more than they bargained for.

I have no idea how many network developers there are in the world but:
1) Many people may be installing this from pypi as a dependency of
some other application that they use. So you should think that it
counts something closer to "users" rather than developers.
2) There are problems with the download counts on PyPI but the numbers
above are sufficiently high that they should indicate a wide level of
usage of the libraries.


Oscar


From neilc at norwich.edu  Tue Mar 11 09:20:35 2014
From: neilc at norwich.edu (Neil Cerutti)
Date: Tue, 11 Mar 2014 13:20:35 +0000 (UTC)
Subject: Closure/method definition question for Python 2.7
References: <mailman.8014.1394472539.18130.python-list@python.org>
 <87vbvmq7l3.fsf@elektro.pacujo.net>
Message-ID: <lfn2j3$rgd$1@ger.gmane.org>

On 2014-03-10, Marko Rauhamaa <marko at pacujo.net> wrote:
> "Brunick, Gerard:(Constellation)" <Gerard.Brunick at constellation.com>:
>
>> class Test(object):
>>     x = 10
>>
>>     def __init__(self):
>>         self.y = x
>>
>> t = Test()
>> ---
>>
>> raises
>>
>> NameError: global name 'x' is not defined.
>
> In the snippet, x is neither local to __init__() nor global to
> the module. It is in the class scope. You can refer to it in
> one of two ways:
>
>    Test.x
>
> or:
>
>    self.x

The latter will work only to read the class variable. If you
assign to self.x you'll create a new instance variable that hides
the class variable.

-- 
Neil Cerutti



From neilc at norwich.edu  Tue Mar 11 10:37:50 2014
From: neilc at norwich.edu (Neil Cerutti)
Date: Tue, 11 Mar 2014 14:37:50 +0000 (UTC)
Subject: golang OO removal,  benefits. over python?
References: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
Message-ID: <lfn73t$88u$1@ger.gmane.org>

On 2014-03-10, flebber <flebber.crue at gmail.com> wrote:
> I was wondering if a better programmer than I could explain if
> the removal of OO features in golang really does offer an great
> benefit over python.
>
> An article I was reading ran through a brief overview of golang
> in respect of OO features
> http://areyoufuckingcoding.me/2012/07/25/object-desoriented-language/
> .
>
> maybe removing OO features would be a benefit to c++ users or
> Java users but python?
>
> As I have seen an interesting reddit or two of people trying to
> figure out go today it was a ruby user, totally lost with
> structs.
>
> So anecdotally is actually python and ruby users changing to
> Go, here is a blog and reddit from Rob Pike.
> http://www.reddit.com/comments/1mue70
>
> Why would a Python user change to go except for new and
> interesting?

Static typing combined with duck typing and simple distribution
of applications is a draw. Go's tools are pretty awesome, and are
scheduled for improvements.

If you can get by with its built in types (or simple aggregates
of them) it feels quite expressive.

-- 
Neil Cerutti



From solipsis at pitrou.net  Tue Mar 11 11:57:38 2014
From: solipsis at pitrou.net (Antoine Pitrou)
Date: Tue, 11 Mar 2014 15:57:38 +0000 (UTC)
Subject: which async framework?
Message-ID: <>

Chris Withers <chris <at> simplistix.co.uk> writes:
> 
> The protocols are all financial (do we really not have a pure-python FIX 
> library?!) but none are likely to have existing python implementations.

If you are mostly writing protocol implementations (aka parsers and
serializers), then you should consider writing them in a way that's
framework-agnostic.

See as an example:
https://pypi.python.org/pypi/obelus/0.1

(if you really want to settle on a single framework and don't mind
supporting old Python versions, then I recommend asyncio)

Regards

Antoine.




From solipsis at pitrou.net  Tue Mar 11 12:01:39 2014
From: solipsis at pitrou.net (Antoine Pitrou)
Date: Tue, 11 Mar 2014 16:01:39 +0000 (UTC)
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
Message-ID: <loom.20140311T170030-477@post.gmane.org>

Sturla Molden <sturla.molden <at> gmail.com> writes:
> 
> Chris Withers <chris <at> simplistix.co.uk> wrote:
> > Hi All,
> > 
> > I see python now has a plethora of async frameworks and I need to try 
> > and pick one to use from:
> > 
> > - asyncio/tulip
> > - tornado
> > - twisted
> 
> I'd go for using iocp, epoll and kqueue/kevent directly. Why bother to
> learn a framework? You will find epoll and kqueue/kevent in the select
> module and iocp in pywin32.

Yes, why use a library when you can rewrite it all yourself?
Actually, you should probably issue system calls to the kernel directly,
the libc is overrated (as is portability, I suppose).

Regards

Antoine.




From Joshua.R.English at gmail.com  Tue Mar 11 12:13:17 2014
From: Joshua.R.English at gmail.com (Josh English)
Date: Tue, 11 Mar 2014 09:13:17 -0700 (PDT)
Subject: Oddity using sorted with key
Message-ID: <058a4a9e-7893-44ef-97c0-999a3589e82a@googlegroups.com>

I am running into a strange behavior using the sorted function in Python 2.7. The key parameter is not behaving as the docs say it does:

Here is a snippet of code, simplified from my full program:

#begin code
class Thing(object):
    def __init__(self, name):
        self.name = name

    def __repr__(self):
        return "Thing %s" % self.name


stuff = [Thing('a'), Thing('C'), Thing('b'), Thing('2')]
more_stuff = [Thing('d'), Thing('f')]

all_the_stuff = stuff + more_stuff

print list(sorted(all_the_stuff, key=lambda x: x.name.lower))
print list(sorted(all_the_stuff, key=lambda x: x.name.lower()))

# END

The output is:

[Thing d, Thing f, Thing 2, Thing a, Thing b, Thing C]
[Thing 2, Thing a, Thing b, Thing C, Thing d, Thing f]

The second call to sorted works as expected. Just using the method doesn't sort properly.

Any ideas why I'm seeing two different results? Especially as the correct form is giving me the wrong results?

Josh English


From g.rodola at gmail.com  Tue Mar 11 12:18:33 2014
From: g.rodola at gmail.com (Giampaolo Rodola')
Date: Tue, 11 Mar 2014 17:18:33 +0100
Subject: which async framework?
In-Reply-To: <164829410416225465.523179sturla.molden-gmail.com@news.gmane.org>
References: <531E22DF.7030709@simplistix.co.uk>
 <164829410416225465.523179sturla.molden-gmail.com@news.gmane.org>
Message-ID: <CAFYqXL-wr3QXBOymi_xZ9uDOepodoMRmRyfH_C-eHGjRNTHB3g@mail.gmail.com>

On Tue, Mar 11, 2014 at 11:17 AM, Sturla Molden <sturla.molden at gmail.com>wrote:

> Chris Withers <chris at simplistix.co.uk> wrote:
> > Hi All,
> >
> > I see python now has a plethora of async frameworks and I need to try
> > and pick one to use from:
> >
> > - asyncio/tulip
> > - tornado
> > - twisted
>
> Looking at Tornado's examples on the web I find this:
>
>     tornado.ioloop.IOLoop.instance().start()
>
> This single line of code says more than thousand words. But it boils down
> to:
>
> (1)  This was written by some Java guys.
> (2)  Someone used Python to write Java.
>
> And that's all I need to know about Tornado.


Tornado is actually very Pythonic and has a very well written and modern
code base.  I think "tornado.ioloop.IOLoop.instance().start()" is the way
it is in order to let you use multiple IO loops in different threads but I
can't think of other places where such an idiom is used.
What one might find a little Java-esque at a first glance is Twisted,
because of zope.interface and the camelCase notation, but definitively not
Tornado.

-- 
Giampaolo - http://grodola.blogspot.com
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From ckaynor at zindagigames.com  Tue Mar 11 12:20:43 2014
From: ckaynor at zindagigames.com (Chris Kaynor)
Date: Tue, 11 Mar 2014 09:20:43 -0700
Subject: Oddity using sorted with key
In-Reply-To: <058a4a9e-7893-44ef-97c0-999a3589e82a@googlegroups.com>
References: <058a4a9e-7893-44ef-97c0-999a3589e82a@googlegroups.com>
Message-ID: <CALvWhxuDsuLt6OXCbKc97SH62sr17c7iJt6B2EDqhv0cx815Xg@mail.gmail.com>

On Tue, Mar 11, 2014 at 9:13 AM, Josh English <Joshua.R.English at gmail.com>wrote:

> print list(sorted(all_the_stuff, key=lambda x: x.name.lower))
>

In this case, the key being sorted on is the function object x.name.lower,
not the result of the call.

It might make more sense if you break the lambda out into a separate def
statement, like this:
def myKeyFunc(x):
    return x.name.lower # Return the function that produces the lower-cased
name.
print list(sorted(all_the_stuff, key=myKeyFunc))



>  print list(sorted(all_the_stuff, key=lambda x: x.name.lower()))
>

In this case, you are calling x.name.lower, and the key being used is the
result of that call.

And heres what this one looks like broken down:
def myKeyFunc(x):
    return x.name.lower() # Return the lower-cased name.
print list(sorted(all_the_stuff, key=myKeyFunc))

Chris
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From emile at fenx.com  Tue Mar 11 12:23:57 2014
From: emile at fenx.com (emile)
Date: Tue, 11 Mar 2014 09:23:57 -0700
Subject: Oddity using sorted with key
In-Reply-To: <058a4a9e-7893-44ef-97c0-999a3589e82a@googlegroups.com>
References: <058a4a9e-7893-44ef-97c0-999a3589e82a@googlegroups.com>
Message-ID: <lfndak$rk4$1@ger.gmane.org>

On 03/11/2014 09:13 AM, Josh English wrote:
> I am running into a strange behavior using the sorted function in Python 2.7. The key parameter is not behaving as the docs say it does:
>
> Here is a snippet of code, simplified from my full program:
>
> #begin code
> class Thing(object):
>      def __init__(self, name):
>          self.name = name
>
>      def __repr__(self):
>          return "Thing %s" % self.name
>
>
> stuff = [Thing('a'), Thing('C'), Thing('b'), Thing('2')]
> more_stuff = [Thing('d'), Thing('f')]
>
> all_the_stuff = stuff + more_stuff
>
> print list(sorted(all_the_stuff, key=lambda x: x.name.lower))

in this case everything sorts by the same value of the bound method of 
name.lower.  You could have used "".lower, which has the same value as 
x.name.lower, and gotten the same results.

> print list(sorted(all_the_stuff, key=lambda x: x.name.lower()))

in this case you're sorting by the lower case value of x.name, which is 
what you want.


Emile



> # END
>
> The output is:
>
> [Thing d, Thing f, Thing 2, Thing a, Thing b, Thing C]
> [Thing 2, Thing a, Thing b, Thing C, Thing d, Thing f]
>
> The second call to sorted works as expected. Just using the method doesn't sort properly.
>
> Any ideas why I'm seeing two different results? Especially as the correct form is giving me the wrong results?
>
> Josh English
>




From gordon at panix.com  Tue Mar 11 12:25:29 2014
From: gordon at panix.com (John Gordon)
Date: Tue, 11 Mar 2014 16:25:29 +0000 (UTC)
Subject: Oddity using sorted with key
References: <058a4a9e-7893-44ef-97c0-999a3589e82a@googlegroups.com>
Message-ID: <lfnddo$3fr$1@reader1.panix.com>

In <058a4a9e-7893-44ef-97c0-999a3589e82a at googlegroups.com> Josh English <Joshua.R.English at gmail.com> writes:

> print list(sorted(all_the_stuff, key=lambda x: x.name.lower))
> print list(sorted(all_the_stuff, key=lambda x: x.name.lower()))

> # END

> The output is:

> [Thing d, Thing f, Thing 2, Thing a, Thing b, Thing C]
> [Thing 2, Thing a, Thing b, Thing C, Thing d, Thing f]

> Any ideas why I'm seeing two different results? Especially as the correct
> form is giving me the wrong results?

Why do you say that 'key=lambda x: x.name.lower' is the correct form? That
returns the str.lower() function object, which is a silly thing to sort
on.  Surely you want to sort on the *result* of that function, which is
what your second print does.

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon at panix.com    watch 'House', or a real serial killer to watch 'Dexter'.



From __peter__ at web.de  Tue Mar 11 12:43:45 2014
From: __peter__ at web.de (Peter Otten)
Date: Tue, 11 Mar 2014 17:43:45 +0100
Subject: Oddity using sorted with key
References: <058a4a9e-7893-44ef-97c0-999a3589e82a@googlegroups.com>
Message-ID: <lfnefj$auo$1@ger.gmane.org>

Josh English wrote:

> I am running into a strange behavior using the sorted function in Python

> print list(sorted(all_the_stuff, key=lambda x: x.name.lower))
> print list(sorted(all_the_stuff, key=lambda x: x.name.lower()))

Let's simplify your example some more:

>>> items = ["B", "2", "a"]
>>> sorted(items, key=lambda x: x.lower())
['2', 'a', 'B']

That certainly works. Let's have a look at the keys used for the sorting:

>>> for item in items:
...     print item, "-->", (lambda x: x.lower())(item)
... 
B --> b
2 --> 2
a --> a

Now on to your first example. What are the keys in this case?

>>> for item in items:
...     print item, "-->", (lambda x: x.lower)(item)
... 
B --> <built-in method lower of str object at 0x7fd7ae45d260>
2 --> <built-in method lower of str object at 0x7fd7ae3e40f8>
a --> <built-in method lower of str object at 0x7fd7ae43d648>

Just a bunch of bound methods. These compare by id(), basically the memory 
address of the bound method object, not something that makes a lot of sense 
as a sort key.

> 2.7. The key parameter is not behaving as the docs say it does:

You may be misled by the mention of key=str.lower

str.lower is an unbound method, and if you pass it to sorted() together with 
a list of strings, it results in a call

str.lower(item) # item is a string

which is equivalent to

item.lower() # item is a string

So while it doesn't work for a list of Thing instances, if you have bare 
strings you can do

>>> sorted(items, key=str.lower)
['2', 'a', 'B']




From steve+comp.lang.python at pearwood.info  Tue Mar 11 12:46:51 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 11 Mar 2014 16:46:51 GMT
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
 <bo7jo9Fsaf1U1@mid.individual.net>
 <mailman.8040.1394534428.18130.python-list@python.org>
Message-ID: <531f3dfb$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 11 Mar 2014 04:39:39 -0600, Ian Kelly wrote:

> On Mon, Mar 10, 2014 at 11:03 PM, Gregory Ewing
> <greg.ewing at canterbury.ac.nz> wrote:
>> As far as observable effects are concerned, it's quite clear: mutable
>> objects can *always* be updated in-place, and immutable objects can
>> *never* be.
> 
> Hm. Consider the circle-ellipse problem.

Oh, not that old chestnut! The circle-ellipse problem demonstrates one 
limitation of OOP (specifically "subtype polymorphism"), as well as a 
general difficulty with hierarchical taxonomies. Mammals have hair -- 
what do you make of hairless[1] dolphins? Circle/Ellipse is not a good 
place to start from in order to critic augmented assignment in Python. 
You're starting from a place where inheritance itself is problematic, so 
naturally you're going to find problems.


> Briefly, a circle is-an ellipse, so in an inheritance hierarchy it is
> natural to make Circle a subclass of Ellipse.

Natural and wrong. It's only natural if you don't think through the 
consequences. As you go on to say:

> Now suppose the Ellipse has a stretch method that
> mutates the ellipse by changing the length of one of its axes while
> preserving the other.  To avoid violating LSP, the Circle class must
> support all the methods of its ancestor.  However it cannot, because the
> stretch method would invalidate the invariant of the Circle class that
> both of its axes must always be equal.

Right. So *Circles cannot be Ellipses*, not without violating the Liskov 
Substitution Principle. If I think that they are, I haven't thought it 
through. Nor can Ellipses be Circles. That's the problem of the Circle/
Ellipse relationship.

(Aside: the LSP is not a Law Of Physics that cannot be touched. There are 
other OOP models that don't require LSP.)

Even in the case of immutable shapes, one might not wish to inherit 
Circle from Ellipsis. Ellipses have five degrees of freedom:

2 x position
size (scale)
orientation
shape

while circles only have three:

2 x position
size

Orientation and shape are meaningless for circles! So they should not 
inherit from a class where they are meaningful: given the LSP, a subclass 
cannot be more restrictive than a superclass.


> There are a number of possible solutions.  One possibility would be to
> copy the Circle as an Ellipse and return the new object instead of
> mutating it. Then you have the situation where, given a mutable object
> x that satisfies isinstance(x, Ellipse), the stretch method *may* be
> able to update the object in-place, or it *may* not.

That is a really lousy design. Of course we are free to create classes 
with ugly, inconsistent, stupid or unworkable APIs if we like. Python 
won't stop us:

class MyList(list):
    def append(self, obj):
        if len(self) % 17 == 3:
            return self + [obj]
        super(MyList, self).append(obj)



> I can't think of a reasonable example that would replace the stretch
> method here with an augmented assignment, but then it is rather late.
> 
>> It might be the obvious way for that particular operation on that
>> particular type. 

Um, yes? Nobody suggests that a method of type X has to be the most 
obvious way for *any operation* on *any type*. What's your point?


> But what about all the others? What's the obvious way
>> to spell in-place set intersection, for example? 

I would expect it to be &=, let's find out if I'm right:

py> a = set("abcde")
py> b = a  # save a reference to it
py> c = set("cdefg")
py> a &= c
py> a, b
({'c', 'd', 'e'}, {'c', 'd', 'e'})
py> a is b
True


>> (Quickly -- no peeking at the docs!)

The only reason I'd need to look at the docs is because I always forget 
whether & is intersection and | is union, or the other way around. But 
having remembered which is which, going from & to &= was easy.


> You mean set.intersection_update?  The in-place set methods are not hard
> to remember, because they all end in _update.

And hard to spell.




[1] Technically they aren't *entirely* hairless. They may have a few 
hairs around the blowhole, and baby dolphins are born with whiskers which 
they soon lose. But from a functional perspective, they are hairless.


-- 
Steven D'Aprano



From invalid at invalid.invalid  Tue Mar 11 12:52:18 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Tue, 11 Mar 2014 16:52:18 +0000 (UTC)
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <mailman.8049.1394553908.18130.python-list@python.org>
Message-ID: <lfnf02$q0c$1@reader1.panix.com>

On 2014-03-11, Antoine Pitrou <solipsis at pitrou.net> wrote:
> Sturla Molden <sturla.molden <at> gmail.com> writes:
>> 
>> Chris Withers <chris <at> simplistix.co.uk> wrote:
>> > Hi All,
>> > 
>> > I see python now has a plethora of async frameworks and I need to try 
>> > and pick one to use from:
>> > 
>> > - asyncio/tulip
>> > - tornado
>> > - twisted
>> 
>> I'd go for using iocp, epoll and kqueue/kevent directly. Why bother to
>> learn a framework? You will find epoll and kqueue/kevent in the select
>> module and iocp in pywin32.
>
> Yes, why use a library when you can rewrite it all yourself?
> Actually, you should probably issue system calls to the kernel directly,
> the libc is overrated (as is portability, I suppose).

And don't bother with device drivers for the network adapters either.
Just map their PCI regions in to user-space and twiddle the reigisters
directly!  ;)

[I do that when testing PCI boards with C code, and one of these days
I'm going to figure out how to do it with Python.]

-- 
Grant Edwards               grant.b.edwards        Yow! It's a hole all the
                                  at               way to downtown Burbank!
                              gmail.com            


From Joshua.R.English at gmail.com  Tue Mar 11 13:02:16 2014
From: Joshua.R.English at gmail.com (Josh English)
Date: Tue, 11 Mar 2014 10:02:16 -0700 (PDT)
Subject: Oddity using sorted with key
In-Reply-To: <lfnddo$3fr$1@reader1.panix.com>
References: <058a4a9e-7893-44ef-97c0-999a3589e82a@googlegroups.com>
 <lfnddo$3fr$1@reader1.panix.com>
Message-ID: <4f58f242-b974-4fa0-a2c7-115b6f50e3af@googlegroups.com>

On Tuesday, March 11, 2014 9:25:29 AM UTC-7, John Gordon wrote:
> 
> 
> 
> 
> Why do you say that 'key=lambda x: x.name.lower' is the correct form? That
> 
> returns the str.lower() function object, which is a silly thing to sort
> 
> on.  Surely you want to sort on the *result* of that function, which is
> 
> what your second print does.
> 


>From http://docs.python.org/2/library/functions.html:

key specifies a function of one argument that is used to extract a comparison key from each list element: key=str.lower. The default value is None (compare the elements directly).

And from https://wiki.python.org/moin/HowTo/Sorting/:

The value of the key parameter should be a function that takes a single argument and returns a key to use for sorting purposes. This technique is fast because the key function is called exactly once for each input record.

...

Of course, now that I re-read that, I was mistaking the lambda function with the definition of the lambda function. Stupid me.



From Joshua.R.English at gmail.com  Tue Mar 11 13:03:31 2014
From: Joshua.R.English at gmail.com (Josh English)
Date: Tue, 11 Mar 2014 10:03:31 -0700 (PDT)
Subject: Oddity using sorted with key
In-Reply-To: <mailman.8053.1394556238.18130.python-list@python.org>
References: <058a4a9e-7893-44ef-97c0-999a3589e82a@googlegroups.com>
 <mailman.8053.1394556238.18130.python-list@python.org>
Message-ID: <a95f54ac-0a80-419b-a020-909522d4fec7@googlegroups.com>

A comprehensive and educational answer, Peter. Thank you.

Josh


From jkn_gg at nicorp.f9.co.uk  Tue Mar 11 13:13:10 2014
From: jkn_gg at nicorp.f9.co.uk (jkn)
Date: Tue, 11 Mar 2014 10:13:10 -0700 (PDT)
Subject: which async framework?
In-Reply-To: <lfnf02$q0c$1@reader1.panix.com>
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <mailman.8049.1394553908.18130.python-list@python.org>
 <lfnf02$q0c$1@reader1.panix.com>
Message-ID: <7bee65ea-2779-4d60-b997-889493bec87e@googlegroups.com>

Hi Grant

On Tuesday, 11 March 2014 16:52:18 UTC, Grant Edwards  wrote:

[...]
> 
> And don't bother with device drivers for the network adapters either.
> Just map their PCI regions in to user-space and twiddle the reigisters
> directly!  ;)
> 
> [I do that when testing PCI boards with C code, and one of these days
> I'm going to figure out how to do it with Python.]

Heh - just about the first 'real' thing I did in Python, back around 2001
or so, was to write a 'Device Driver' library to allow direct access to
memory-mapped I/O via Python. It compiled under both Windows and Linux
and I proved it using an ISA I/O board with loads of 8255s and LEDs
hanging off it.

As well as a learning exercise it was sort-of intended as a first step
toward robotic control using Python. I hopen to rework it for similar
PCI-based I/O boards (to do the sort of thing you mention), but never got
a round tuit...

    Cheers
    jon N


From rosuav at gmail.com  Tue Mar 11 13:17:16 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 12 Mar 2014 04:17:16 +1100
Subject: which async framework?
In-Reply-To: <loom.20140311T170030-477@post.gmane.org>
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
Message-ID: <CAPTjJmoMFqZeUQSjTkG49RBZriGVkVaqPWZ+kMLxODvKWEbr6Q@mail.gmail.com>

On Wed, Mar 12, 2014 at 3:01 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> Yes, why use a library when you can rewrite it all yourself?
> Actually, you should probably issue system calls to the kernel directly,
> the libc is overrated (as is portability, I suppose).

It's a trade-off, of course. I am fluent in over six million forms of
TCP socket communication (give or take), so I'll often skip the
libraries and just directly connect a socket. But on the flip side,
some protocols are just way more convenient to let a library handle.
An HTTP POST request, for instance, requires - potentially - a whole
lot of escaping and merging and stuff, or a simple call to one
function with a dictionary of form data. But I like to retain close
familiarity with the actual protocols, in case I'm trying to transfer
a file onto a target system that provides something buggy or
incomplete... most notably, the innumerable platforms whose FTP
clients don't support passive mode. (RFC 959 specified it in 1985, why
doesn't the default WinXP client support it??) I've written a good few
FTP clients for that reason.

There's a huge difference between something meant to do a huge amount
of work long-term and something to just quickly move some data across
a VM boundary. For the latter, I'll do whatever's quickest *right
now*, and that may well mean "don't bother figuring out the XYZ
module, just do it over a plain socket".

ChrisA


From jimsgibson at gmail.com  Tue Mar 11 13:18:37 2014
From: jimsgibson at gmail.com (Jim Gibson)
Date: Tue, 11 Mar 2014 10:18:37 -0700
Subject: querry  on queue ( thread safe ) multithreading
References: <de667c72-c1f7-449e-86cf-ce8c6818b87d@googlegroups.com>
Message-ID: <110320141018377289%jimsgibson@gmail.com>

In article <de667c72-c1f7-449e-86cf-ce8c6818b87d at googlegroups.com>,
Jaiprakash Singh <jaiprakash at wisepromo.com> wrote:

> hey i am working on scraping a site , so  i am using multi-threading concept.
> i wrote a code based on queue (thread safe) but still my code block out after
> sometime, please help , i have searched a lot but unable to resolve it.
> please help i stuck here.

Do you really want to subject the web server to 150 simultaneous
requests? Some would consider that a denial-of-service attack.

When I scrape a site, and I have been doing that occasionally of late,
I put a 10-second sleep after each HTTP request. That makes my program
more considerate of other people's resources and a better web citizen.
It is also much easier to program.

-- 
Jim Gibson


From sturla.molden at gmail.com  Tue Mar 11 13:44:24 2014
From: sturla.molden at gmail.com (Sturla Molden)
Date: Tue, 11 Mar 2014 17:44:24 +0000 (UTC)
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
Message-ID: <372076480416251284.821607sturla.molden-gmail.com@news.gmane.org>

Antoine Pitrou <solipsis at pitrou.net> wrote:

> Yes, why use a library when you can rewrite it all yourself?

This assumes something equivalent to the library will have to be written.
But if it can be replaced with something very minimalistic it is just
bloat. I would also like to respond that the select module and pywin32 are
libraries. So what we are talking about here is not using a library versus
issuing low-level system calls, but using a cross-platform library instead
of having separate modules with system calls for Linux, *BSD/Apple and
Windows.

Another thing is that co-routines and "yield from" statements just makes it
hard to follow the logic of the program. I still have to convince myself
that a library for transforming epoll function calls into co-routines is
actually useful. If it just turns otherwise readable code into something
most Python programmers cannot read it is better left out of the project.

Sturla



From solipsis at pitrou.net  Tue Mar 11 14:43:45 2014
From: solipsis at pitrou.net (Antoine Pitrou)
Date: Tue, 11 Mar 2014 18:43:45 +0000 (UTC)
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <372076480416251284.821607sturla.molden-gmail.com@news.gmane.org>
Message-ID: <loom.20140311T193409-649@post.gmane.org>

Sturla Molden <sturla.molden <at> gmail.com> writes:
> 
> Antoine Pitrou <solipsis <at> pitrou.net> wrote:
> 
> > Yes, why use a library when you can rewrite it all yourself?
> 
> This assumes something equivalent to the library will have to be written.
> But if it can be replaced with something very minimalistic it is just
> bloat. I would also like to respond that the select module and pywin32 are
> libraries.

Lower-level ones, though. Just like C malloc() is lower-level than
Python's memory management.

This is the usual assumption that high-level libraries are made of useless
cruft piled up by careless programmers. But there are actual reasons 
why these frameworks have a significant amount of code, and people who 
decide to ignore those reasons are simply bound to reimplement 
non-trivial parts of those frameworks in less careful and less tested
ways (and they have to maintain it themselves afterwards).

What irks me with your response is that you phrased it as though writing
a good event loop was an almost trivial thing to do, which it is not
once you start considering multiple use cases and constraints. It is
quite irresponsible to suggest people don't need the power of network
programming frameworks. I would personally distrust a programmer who
chooses to reimplement their own event loop, except if they happen to
have a very brilliant track record.

> Another thing is that co-routines and "yield from" statements just
> makes it hard to follow the logic of the program. 

That's an optional part of Tornado and asyncio, though. It is very
reasonable to use Tornado or asyncio and still code in purely
callback-driven style (even though Guido himself prefers the coroutine
style).

Regards

Antoine.




From rosuav at gmail.com  Tue Mar 11 15:02:28 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 12 Mar 2014 06:02:28 +1100
Subject: which async framework?
In-Reply-To: <loom.20140311T193409-649@post.gmane.org>
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <372076480416251284.821607sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T193409-649@post.gmane.org>
Message-ID: <CAPTjJmqe5vEFwnyM-wE4a7__Tc1C3RbMaJyW2Pxikh002vSxeg@mail.gmail.com>

On Wed, Mar 12, 2014 at 5:43 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> This is the usual assumption that high-level libraries are made of useless
> cruft piled up by careless programmers. But there are actual reasons
> why these frameworks have a significant amount of code, and people who
> decide to ignore those reasons are simply bound to reimplement
> non-trivial parts of those frameworks in less careful and less tested
> ways (and they have to maintain it themselves afterwards).

Once again, that's a judgment call. Those frameworks are usually
written to be generic and to support lots of different systems, and if
all you need is one of them, it's not so obvious that you 'ought to'
use the framework. You do not need Joomla when all you want is a whole
lot of static HTML files by one person - look for a simpler framework
that doesn't put heaps of emphasis on user management, or no framework
at all (just some nice templating system).

But yes. If you're reimplementing something, you have to have a VERY
good reason. I'm much more likely to write a program that edits
bindfiles than to write a DNS server (although I have done both - Pike
makes it easy to do the latter, and I had one situation where I was
using DNS in such a way that I actually needed to generate responses
on-the-fly based on rules, rather than pre-write everything), because
BIND9 already handles pretty much everything, and its definition files
are simple and easy to manipulate. (That said, though, I have
*frequently* gone for some kind of meta-file with a script that
creates the actual bindfiles. Helps with keeping things consistent,
making sure I do the version updates, and so on. But that's not
rewriting BIND.)

ChrisA


From tjreedy at udel.edu  Tue Mar 11 15:41:30 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 11 Mar 2014 15:41:30 -0400
Subject: which async framework?
In-Reply-To: <531EC0E6.10402@simplistix.co.uk>
References: <531E22DF.7030709@simplistix.co.uk> <lflcha$2mf$1@ger.gmane.org>
 <531EC0E6.10402@simplistix.co.uk>
Message-ID: <lfnotf$i2a$1@ger.gmane.org>

On 3/11/2014 3:53 AM, Chris Withers wrote:
> On 10/03/2014 21:57, Terry Reedy wrote:
>>> I'd like to be able to serve the rest of the web api using a pyramid
>>> wsgi app if possible, and I'd like to be able to write the things that
>>> process requests in and validation out in a synchronous fashion, most
>>> likely spinning off a thread for each one.
>>
>> If you are writing 'standard' blocking, synchronous code, I am not sure
>> why you would use any of the above.
>
> The idea I have is to do all the networking async based on a declarative
> set of messages in and recording all messages out and then hand that set
> of messages off to a syncronous layer to make assertions, record into a
> database, etc.

In the absence of an event-loop oriented queue, putting jobs on a thread 
queue for a job-handler makes sense.

>>> The protocols are all financial (do we really not have a pure-python FIX
>>> library?!) but none are likely to have existing python implementations.
>>>
>>> How should I pick between the options? What would people recommend and
>>> why?
>>
>> I know nothing of tornado. I personally would use asyncio over twisted
>> if I could because it is simpler, in the stdlib, has the option to write
>> 'untwisted' non-blocking code similar to blocking code, and the docs
>> easier for me to read.

> Guess I was expecting more of a response.

Let me try again. I read the Twisted docs a couple of years ago.  While 
I could deal with the interface, I understand why it is called 'twisted' 
and why Guido does not particularly like it. I read the asyncio doc 
before the most recent revisions and found it easier to understand. I 
personally like the co-routine layer.  But I know that this is very much 
a personal preference.  (Sturla just confirmed this by posting the 
opposite response to the coroutine interface.) So I suggest you spend an 
hour with the doc for each of the three candidates.

> I suspect I'll just end up cross-posting to the various mailing lists,

Bad idea. Post separately if you must.

 > which I hope won't cause too much offence or kick off any flame wars.

It would do both.

> I'm faced with a difficult choice that I suspect many in our community
> are, just trying to find out how to make the best decision :-)

The asyncio event loop interface was designed with knowledge of other 
event loops, including but not limited to those of twisted and tornado. 
The implementation in asyncio is intended to be replaceable by other 
implementations that include the same interface. I do not know if there 
are adapters yet for the twisted and tornado loops, but I expect there 
will be, official or not. Part of Guido's intent is to reduce 
single-framework lockin. If you start with asyncio, and decide you want 
to use some Twisted protocols, you should be able to (at least in the 
future) without dumping your current code.

-- 
Terry Jan Reedy



From ian.g.kelly at gmail.com  Tue Mar 11 16:21:52 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 11 Mar 2014 14:21:52 -0600
Subject: golang OO removal, benefits. over python?
In-Reply-To: <878usitplp.fsf@elektro.pacujo.net>
References: <95cb6bd9-5030-4389-9891-578bb87af219@googlegroups.com>
 <mailman.7983.1394437871.18130.python-list@python.org>
 <878usitplp.fsf@elektro.pacujo.net>
Message-ID: <CALwzid=nSMst2M7o_UfEpYJ96kE+0K7SvhJeeVta1Mh8+sKeuA@mail.gmail.com>

On Mon, Mar 10, 2014 at 2:38 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> On the whole though I think that the language is not yet mature enough
>> to be able to seriously compete with more established languages like
>> Python or Java.
>
> Also, is there anything seriously lacking in Python, Java and C?
>
> I was very interested in Go when it came out, but was turned off by the
> fact that you had so have a Google account to effectively participate in
> the community.

Concurrency is one area where Go beats Python hands down.  The newish
multiprocessing module helps with that, but it is still rather heavy
compared to the light-weight processes used by Go's goroutines.


From sturla.molden at gmail.com  Tue Mar 11 16:36:11 2014
From: sturla.molden at gmail.com (Sturla Molden)
Date: Tue, 11 Mar 2014 20:36:11 +0000 (UTC)
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <372076480416251284.821607sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T193409-649@post.gmane.org>
Message-ID: <1659582220416262070.234156sturla.molden-gmail.com@news.gmane.org>

Antoine Pitrou <solipsis at pitrou.net> wrote:

> This is the usual assumption that high-level libraries are made of useless
> cruft piled up by careless programmers. 

It often is the case, particularly in network programming.

But in this case the programmer is Guido, so it doesn't apply. :)


> What irks me with your response is that you phrased it as though writing
> a good event loop was an almost trivial thing to do, which it is not
> once you start considering multiple use cases and constraints. 

Right. But in my programs an event loops does not have multiple usecases. I
know all the details about my usecase. 

I am more concerned that multiple frameworks have their own event loops. 

Sturla



From greg.ewing at canterbury.ac.nz  Tue Mar 11 17:23:27 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 12 Mar 2014 10:23:27 +1300
Subject: Tuples and immutability
In-Reply-To: <531f3dfb$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>	<CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>	<CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>	<mailman.7473.1393598638.18130.python-list@python.org>	<XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>	<mailman.7920.1394252278.18130.python-list@python.org>	<bo1rjpFll5mU1@mid.individual.net>	<mailman.7944.1394332838.18130.python-list@python.org>	<bo46qcF6dofU1@mid.individual.net>	<mailman.7972.1394408612.18130.python-list@python.org>	<bo7jo9Fsaf1U1@mid.individual.net>	<mailman.8040.1394534428.18130.python-list@python.org>
 <531f3dfb$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <bo9d69F9vf6U1@mid.individual.net>

Steven D'Aprano wrote:
> On Tue, 11 Mar 2014 04:39:39 -0600, Ian Kelly wrote:
> 
>>On Mon, Mar 10, 2014 at 11:03 PM, Gregory Ewing
 >
>>What's the obvious way
>>>to spell in-place set intersection, for example? 
> 
> I would expect it to be &=,

That's my point -- once you know the binary operator for
an operation, the corresponding in-place operator is
obvious. But there's no established standard set of
method names for in-place operations -- each type
does its own thing.

>>You mean set.intersection_update?  The in-place set methods are not hard
>>to remember, because they all end in _update.

For that particular type, maybe, but I wouldn't trust
that rule to extend to other types.

-- 
Greg


From ethan at stoneleaf.us  Tue Mar 11 16:58:17 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Tue, 11 Mar 2014 13:58:17 -0700
Subject: unittest weirdness
Message-ID: <531F78E9.5020103@stoneleaf.us>

So I finally got enough data and enough of an understanding to write some unit tests for my code.

These aren't the first unit tests I've written, but the behavior I'm getting is baffling.

I'm using 2.7.4 and I'm testing some routines which attempt to interpret data from a flat file and create a new flat 
file for later programmatic consumption.

The weird behavior I'm getting:

   - when a test fails, I get the E or F, but no summary at the end
     (if the failure occurs in setUpClass before my tested routines
     are actually called, I get the summary; if I run a test method
     individually I get the summary)

   - I have two classes, but only one is being exercised

   - occasionally, one of my gvim windows is unceremoniously killed
    (survived only by its swap file)

I'm running the tests under sudo as the routines expect to be run that way.

Anybody have any ideas?

--
~Ethan~

--snippet of code--

from VSS.path import Path
from unittest import TestCase, main as Run
import wfbrp

class Test_wfbrp_20140225(TestCase):

     @classmethod
     def setUpClass(cls):
         cls.pp = wfbrp.PaymentProcessor(
             '.../lockbox_file',
             '.../aging_file',
             [
                 Path('month_end_1'),
                 Path('month_end_2'),
                 Path('month_end_3'),
                 ],
             )

     def test_xxx_1(self):
         p = self.pp.lockbox_payments[0]
         # affirm we have what we're expecting
         self.assertEqual(
                 (p.payer, p.ck_num, p.credit),
                 ('a customer', '010101', 10000),
                 )
         self.assertEqual(p.invoices.keys(), ['XXXXXXXXXXX'])
         self.assertEqual(p.invoices.values()[0].amount, 10000)
         # now make sure we get back what we're expecting
         np, b = self.pp._match_invoices(p)
         missing = []
         for inv_num in ('123456', '789012', '345678'):
             if inv_num not in b:
                 missing.append(inv_num)
         if missing:
             raise ValueError('invoices %r missing from batch' % missing)


From greg.ewing at canterbury.ac.nz  Tue Mar 11 17:56:43 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 12 Mar 2014 10:56:43 +1300
Subject: which async framework?
In-Reply-To: <mailman.8055.1394559893.18130.python-list@python.org>
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <mailman.8055.1394559893.18130.python-list@python.org>
Message-ID: <bo9f4lFacnnU1@mid.individual.net>

Sturla Molden wrote:
> Another thing is that co-routines and "yield from" statements just makes it
> hard to follow the logic of the program. I still have to convince myself
> that a library for transforming epoll function calls into co-routines is
> actually useful.

It's not "epoll function calls" that the coroutine style is
intended to replace, it's complex systems of chained callbacks.
They're supposed to make that kind of logic *easier* to follow.
If you haven't had that experience, it may be because you've
only dealt with simple cases.

-- 
Greg


From gordon at panix.com  Tue Mar 11 18:13:39 2014
From: gordon at panix.com (John Gordon)
Date: Tue, 11 Mar 2014 22:13:39 +0000 (UTC)
Subject: unittest weirdness
References: <mailman.8062.1394573210.18130.python-list@python.org>
Message-ID: <lfo1qj$3m3$1@reader1.panix.com>

In <mailman.8062.1394573210.18130.python-list at python.org> Ethan Furman <ethan at stoneleaf.us> writes:

>          if missing:
>              raise ValueError('invoices %r missing from batch' % missing)

It's been a while since I wrote test cases, but I recall using the assert*
methods (assertEqual, assertTrue, etc.) instead of raising exceptions.
Perhaps that's the issue?

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon at panix.com    watch 'House', or a real serial killer to watch 'Dexter'.



From marko at pacujo.net  Tue Mar 11 18:18:24 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 12 Mar 2014 00:18:24 +0200
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <mailman.8055.1394559893.18130.python-list@python.org>
 <bo9f4lFacnnU1@mid.individual.net>
Message-ID: <87bnxcnzv3.fsf@elektro.pacujo.net>

Gregory Ewing <greg.ewing at canterbury.ac.nz>:

> It's not "epoll function calls" that the coroutine style is intended
> to replace, it's complex systems of chained callbacks. They're
> supposed to make that kind of logic *easier* to follow. If you haven't
> had that experience, it may be because you've only dealt with simple
> cases.

The coroutines are definitely something to get into, although I'm
skeptical as well. Epoll and the associated idioms have been with us for
a long time and are well understood.

As for "easy to follow," unfortunately the complexities of network state
machines cannot be abstracted out, and the result is never exactly easy
to the eye.


Marko


From marko at pacujo.net  Tue Mar 11 18:28:42 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 12 Mar 2014 00:28:42 +0200
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <372076480416251284.821607sturla.molden-gmail.com@news.gmane.org>
 <mailman.8056.1394563452.18130.python-list@python.org>
Message-ID: <877g80nzdx.fsf@elektro.pacujo.net>

Antoine Pitrou <solipsis at pitrou.net>:

> This is the usual assumption that high-level libraries are made of
> useless cruft piled up by careless programmers. But there are actual
> reasons why these frameworks have a significant amount of code, and
> people who decide to ignore those reasons are simply bound to
> reimplement non-trivial parts of those frameworks in less careful and
> less tested ways (and they have to maintain it themselves afterwards).

Maybe, maybe not. You can't assume it one way or another.

> What irks me with your response is that you phrased it as though writing
> a good event loop was an almost trivial thing to do,

It's not rocket science. There are pitfalls, to be sure, but the
resulting, solid event loop is not many lines of code. Have had to
implement it numerous times.

That said, asyncio seems to have the necessary facilities in place.
Definitely worth a closer look.

> I would personally distrust a programmer who chooses to reimplement
> their own event loop, except if they happen to have a very brilliant
> track record.

As with all programming, you have to do it right.

If you can't write your own event loop, you probably can't be trusted
with any multithreaded code, which has much more baffling corner cases.


Marko


From ethan at stoneleaf.us  Tue Mar 11 17:37:09 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Tue, 11 Mar 2014 14:37:09 -0700
Subject: unittest weirdness
In-Reply-To: <531F78E9.5020103@stoneleaf.us>
References: <531F78E9.5020103@stoneleaf.us>
Message-ID: <531F8205.8090805@stoneleaf.us>

On 03/11/2014 01:58 PM, Ethan Furman wrote:
>
> Anybody have any ideas?

I suspect the O/S is killing the process.  If I manually select the other class to run (which has all successful tests, 
so no traceback baggage), it runs normally.

--
~Ethan~


From rosuav at gmail.com  Tue Mar 11 18:38:33 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 12 Mar 2014 09:38:33 +1100
Subject: which async framework?
In-Reply-To: <877g80nzdx.fsf@elektro.pacujo.net>
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <372076480416251284.821607sturla.molden-gmail.com@news.gmane.org>
 <mailman.8056.1394563452.18130.python-list@python.org>
 <877g80nzdx.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmqaYuUUBiPNbHAMisV1M7NEcUbXtYX+qgLQu8=zcYQ89A@mail.gmail.com>

On Wed, Mar 12, 2014 at 9:28 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> If you can't write your own event loop, you probably can't be trusted
> with any multithreaded code, which has much more baffling corner cases.

I'm not sure about that. Threads are generally easier to handle,
because each one just does something on its own, sequentially. (The
problem with threads is the resource usage - you need to allocate X
amount of stack space and other execution state, when all you really
need is the socket (or whatever) and some basic state about that.)
Regardless of how you structure your code, you have to ensure that one
handler doesn't tread on another's toes, and with multithreading,
that's _all_ you have to worry about. A proper event loop, handling
events from all sorts of different sources, is far more complicated.

What corner cases are there with threads that you don't have with anything else?

ChrisA


From ethan at stoneleaf.us  Tue Mar 11 18:29:59 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Tue, 11 Mar 2014 15:29:59 -0700
Subject: unittest weirdness
In-Reply-To: <lfo1qj$3m3$1@reader1.panix.com>
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <lfo1qj$3m3$1@reader1.panix.com>
Message-ID: <531F8E67.10709@stoneleaf.us>

On 03/11/2014 03:13 PM, John Gordon wrote:
> Ethan Furman writes:
>
>>           if missing:
>>               raise ValueError('invoices %r missing from batch' % missing)
>
> It's been a while since I wrote test cases, but I recall using the assert*
> methods (assertEqual, assertTrue, etc.) instead of raising exceptions.
> Perhaps that's the issue?

Drat.  Tried it, same issue.  O/S kills it.  :(

--
~Ethan~


From ian.g.kelly at gmail.com  Tue Mar 11 19:06:43 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 11 Mar 2014 17:06:43 -0600
Subject: Tuples and immutability
In-Reply-To: <531f3dfb$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
 <bo7jo9Fsaf1U1@mid.individual.net>
 <mailman.8040.1394534428.18130.python-list@python.org>
 <531f3dfb$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALwzidkQ3FBkRjvn7oqNQ30P+cH5W7ZENPJuPsi5RKBMUZSUOA@mail.gmail.com>

On Tue, Mar 11, 2014 at 10:46 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
>> There are a number of possible solutions.  One possibility would be to
>> copy the Circle as an Ellipse and return the new object instead of
>> mutating it. Then you have the situation where, given a mutable object
>> x that satisfies isinstance(x, Ellipse), the stretch method *may* be
>> able to update the object in-place, or it *may* not.
>
> That is a really lousy design. Of course we are free to create classes
> with ugly, inconsistent, stupid or unworkable APIs if we like. Python
> won't stop us:

That's true but irrelevant to my point, which was to counter the
assertion that mutable types can always be assumed to be able to
perform operations in-place.


From barry at barrys-emacs.org  Tue Mar 11 17:37:34 2014
From: barry at barrys-emacs.org (Barry Scott)
Date: Tue, 11 Mar 2014 21:37:34 +0000
Subject: How to create an instance of a python class from C++
In-Reply-To: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>
References: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>
Message-ID: <8AEE6BCA-0F61-4F9E-A18B-13DB283DC134@barrys-emacs.org>

On 5 Mar 2014, at 00:14, Bill <galaxyblue63 at gmail.com> wrote:

> Hello:
> 
> I can't figure out how to create an instance
> of a python class from 'C++':
> 

Why not use pycxx from http://sourceforge.net/projects/cxx/?

This lib does all the heavy lifting for you for both python2 and python3.
Has docs and examples.

Barry
PyCXX maintainer.



> ( I am relatively new to Python so excuse some of
>  the following. )
> 
> In a .py file I create an ABC and then specialize it:
> 
>    from MyMod import *
>    from abc import ABCMeta, abstractmethod
> 
>    # Declare an abstract base class.
>    class Base(metaclass=ABCMeta):
>        """Base class."""
>        @abstractmethod
>        def description(self):
>            return "From the base class."
> 
>    # Declare a class that inerits from the base.
>    class Derived(Base):
>        """Derived class."""
>        def description(self):
>            return "From the Derived."
> 
>    # Register the derived class.
>    RegisterClass(Derived)
> 
> Then from 'C++' (my implementation of RegisterClass)
> I try to create an instance
> 
>    static PyObject *
>    RegisterClass( PyObject *, PyObject *args ) {       // This gets called ok.
> 
>        PyObject *class_decl;
>        if( ! PyArg_ParseTuple(args, "O", &class_decl) )
>            return NULL;
>        Py_INCREF(class_decl);
> 
>        PyTypeObject *typ = class_decl->ob_type;
> 
>        // Tried this.
>        // PyObject *an = _PyObject_New(class_decl->ob_type); assert(an);
>        // PyObject *desc = PyObject_CallMethod(an,"description",NULL); assert(desc);
> 
>        // Tried this.
>        // PyObject *an = PyType_GenericNew((PyTypeObject *)class_decl->ob_type, NULL, NULL); assert(an);
>        // assert(class_decl); assert(class_decl->ob_type); assert(class_decl->ob_type->tp_new);
> 
>        // This returns something.
>        assert(class_decl); assert(class_decl->ob_type); assert(class_decl->ob_type->tp_new);
>        PyObject *an_inst = class_decl->ob_type->tp_new(class_decl->ob_type,NULL, NULL); assert(an_inst);
>        assert(class_decl->ob_type->tp_init);
> 
>        // This crashes.
>        int ret = class_decl->ob_type->tp_init(an_inst,NULL, NULL); assert(ret == 0);
>        // PyObject_CallMethod(an_inst,"__init__",NULL);
>        // PyObject *an_inst = PyObject_CallMethod(class_decl,"__new__",NULL); assert(an_inst);
> 
>        // Never get here.
>        PyObject *desc = PyObject_CallMethod(an_inst,"description",NULL); assert(desc);
>        char *cp = _PyUnicode_AsString(desc);
>        cerr << "Description:" << cp << endl;
> 
>        return PyLong_FromLong(0);
>    }
> 
>    static PyMethodDef MyModMethods[] = {
>        { "RegisterClass", RegisterClass, METH_VARARGS, "Register class." },
>        {  NULL,           NULL,          0,             NULL             }
>    };
> 
>    static struct PyModuleDef MyModMod = {
>       PyModuleDef_HEAD_INIT,
>       "MyMod",            // name of module
>       NULL,                // module documentation, may be NULL
>       -1,
>       MyModMethods,
>       NULL,
>       NULL,
>       NULL,
>       NULL
>    };
> 
>    PyMODINIT_FUNC
>    PyInit_MyMod( void ) {
>        PyObject* m = PyModule_Create(&MyModMod);
>        if( m == NULL )
>            return NULL;
>            return m;
>    }
> 
>    int
>    main( int, char ** ) {
> 
>        PyImport_AppendInittab( "MyMod", PyInit_MyMod );
> 
>        Py_Initialize();
> 
>        const char *file_name = "z.py";
>        FILE *fp = fopen(file_name,"r");
>        if( fp ) {
>            PyRun_SimpleFileExFlags(fp,file_name,1,0);
>        }
> 
>        Py_Finalize();
> 
>        return 0;
>    }
> -- 
> https://mail.python.org/mailman/listinfo/python-list
> 



From marko at pacujo.net  Tue Mar 11 19:18:52 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 12 Mar 2014 01:18:52 +0200
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <372076480416251284.821607sturla.molden-gmail.com@news.gmane.org>
 <mailman.8056.1394563452.18130.python-list@python.org>
 <877g80nzdx.fsf@elektro.pacujo.net>
 <mailman.8064.1394577523.18130.python-list@python.org>
Message-ID: <87wqg0mihv.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> What corner cases are there with threads that you don't have with
> anything else?

There are numerous. Here's one example: deadlocks due to two threads
taking locks in a different order. The problem crops up naturally with
two intercommunicating classes. It can sometimes be very difficult to
spot or avoid.


Marko


From rosuav at gmail.com  Tue Mar 11 19:38:38 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 12 Mar 2014 10:38:38 +1100
Subject: which async framework?
In-Reply-To: <87wqg0mihv.fsf@elektro.pacujo.net>
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <372076480416251284.821607sturla.molden-gmail.com@news.gmane.org>
 <mailman.8056.1394563452.18130.python-list@python.org>
 <877g80nzdx.fsf@elektro.pacujo.net>
 <mailman.8064.1394577523.18130.python-list@python.org>
 <87wqg0mihv.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmrRaM2tU_-k=W9JOG0YKSsnW_=z4OrXRQJxHcf9HTDUUg@mail.gmail.com>

On Wed, Mar 12, 2014 at 10:18 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> What corner cases are there with threads that you don't have with
>> anything else?
>
> There are numerous. Here's one example: deadlocks due to two threads
> taking locks in a different order. The problem crops up naturally with
> two intercommunicating classes. It can sometimes be very difficult to
> spot or avoid.

Yep. Now how is that not a problem when you use some other model, like
an event loop? The standard methods of avoiding deadlocks (like
acquiring locks in strict order) work exactly the same for all models,
and are just as necessary.

ChrisA


From marko at pacujo.net  Tue Mar 11 20:10:46 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 12 Mar 2014 02:10:46 +0200
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <372076480416251284.821607sturla.molden-gmail.com@news.gmane.org>
 <mailman.8056.1394563452.18130.python-list@python.org>
 <877g80nzdx.fsf@elektro.pacujo.net>
 <mailman.8064.1394577523.18130.python-list@python.org>
 <87wqg0mihv.fsf@elektro.pacujo.net>
 <mailman.8068.1394581121.18130.python-list@python.org>
Message-ID: <87siqomg3d.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Yep. Now how is that not a problem when you use some other model, like
> an event loop? The standard methods of avoiding deadlocks (like
> acquiring locks in strict order) work exactly the same for all models,
> and are just as necessary.

I was simply saying that if you can work with multiple threads, an event
loop shouldn't be a big deal.


Marko


From wuwei23 at gmail.com  Tue Mar 11 20:13:01 2014
From: wuwei23 at gmail.com (alex23)
Date: Wed, 12 Mar 2014 10:13:01 +1000
Subject: Balanced trees
In-Reply-To: <87wqg1oxh4.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>	<mailman.7473.1393598638.18130.python-list@python.org>	<XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>	<bnvctpF5vanU1@mid.individual.net>	<mailman.7920.1394252278.18130.python-list@python.org>	<87eh2d3x8h.fsf_-_@elektro.pacujo.net>	<CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>	<mailman.7937.1394311101.18130.python-list@python.org>	<87eh2ctmht.fsf@elektro.pacujo.net>	<mailman.7941.1394328694.18130.python-list@python.org>	<87zjkz3eo3.fsf@elektro.pacujo.net>	<mailman.7963.1394400019.18130.python-list@python.org>	<87a9czrrax.fsf@elektro.pacujo.net>	<531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>	<87eh2atw6s.fsf@elektro.pacujo.net>	<roy-BE3C76.09590110032014@news.panix.com>	<mailman.8007.1394468681.18130.python-list@python.org>	<8761nmrnfk.fsf@elektro.pacujo.net>	<roy-F30152.19240710032014@news.panix.com>	<531e6643$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87wqg1oxh4.fsf@elektro.pacujo.net>
Message-ID: <lfo8qf$9sm$1@dont-email.me>

On 11/03/2014 8:12 PM, Marko Rauhamaa wrote:
> Python should let skilled professionals do their work. Thankfully, for
> the most part, it does.

Skilled professionals don't solely rely on the standard library, either. 
If you know you need a balanced tree, you'll also know where to find an 
implementation of one.


From rhodri at wildebst.org.uk  Tue Mar 11 20:57:59 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Wed, 12 Mar 2014 00:57:59 -0000
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net> <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net> <roy-F30152.19240710032014@news.panix.com>
 <531e6643$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmqjpz0e9-Rfruo0eJFjgq98UQZ31tgC6eNmhuTptWuK2Q@mail.gmail.com>
 <CALwzidmYeYfeM2TCSgvGrr4XCPocJBPx0GwXNbwEHEoicOEk3Q@mail.gmail.com>
 <mailman.8034.1394512113.18130.python-list@python.org>
Message-ID: <op.xck3mxcw5079vu@gnudebeest>

On Tue, 11 Mar 2014 04:28:25 -0000, Chris Angelico <rosuav at gmail.com>  
wrote:

> On Tue, Mar 11, 2014 at 2:38 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> On Mon, Mar 10, 2014 at 7:45 PM, Chris Angelico <rosuav at gmail.com>  
>> wrote:
>>> No no,
>>> I could make this so much better by using the 80x86 "REP MOVSW"
>>> command (or commands, depending on your point of view). That would be
>>> so much better than all those separate operations the silly compiler
>>> was doing! Roughly an hour of fiddling later, making sure it all still
>>> worked correctly, I discover that... hmm, it's not actually any
>>> faster.
>>
>> Better to have tried and failed though than to have simply accepted
>> what the compiler was doing with no verification at all.
>
> Maybe. But I've learned now that one guy who used to do assembly
> language programming on an 8086 is unlikely to discover something that
> the many authors of a C compiler haven't noticed. Yes, it's possible
> there'll be something specific to my code, like if I'm doing a
> strcpy-like operation that isn't *actually* strcpy (the function will
> be optimized heavily, but a C-level loop might not be recognized), but
> it's more likely the compiler knows better than I do.

That might be true for x86, but it isn't true for ARM for example.   
Apparently it's algorithmically hard to generate ARM code that makes  
efficient use of conditional instructions, and I can almost always write  
tighter, faster code than the compiler generates in consequence.  It's not  
always worth the extra coding time (longer now that I'm not in practise),  
but that's a separate matter.


-- 
Rhodri James *-* Wildebeest Herder to the Masses


From cjwelborn at live.com  Tue Mar 11 22:04:13 2014
From: cjwelborn at live.com (Christopher Welborn)
Date: Tue, 11 Mar 2014 21:04:13 -0500
Subject: beautiful soup get class info
In-Reply-To: <e73d29eb-17bb-472e-bdc4-c38ca904c60f@googlegroups.com>
References: <e73d29eb-17bb-472e-bdc4-c38ca904c60f@googlegroups.com>
Message-ID: <lfofai$9oc$1@ger.gmane.org>

On 03/06/2014 02:22 PM, teddybubu at gmail.com wrote:
> I am using beautifulsoup to get the title and date of the website.
> title is working fine but I am not able to pull the date. Here is the code in the url:
>
>   <span class="date">October 22, 2011</span>
>
> In Python, I am using the following code:
> date1 = soup.span.text
> data=soup.find_all(date="value")
>
> Results in:
>
> []
> March 5, 2014
>
> What is the proper way to get this info?
> Thanks.
>

I believe it's the 'attrs' argument.
http://www.crummy.com/software/BeautifulSoup/bs4/doc/

# Workaround the 'class' problem:
data = soup.find_all(attrs={'class': 'date'})

I haven't tested it, but it's worth looking into.

-- 
\?\      /?/\
  \ \/??\/ / / Christopher Welborn (cj)
   \__/\__/ /  cjwelborn at live?com
    \__/\__/   http://welbornprod.com



From rantingrickjohnson at gmail.com  Tue Mar 11 22:01:43 2014
From: rantingrickjohnson at gmail.com (Rick Johnson)
Date: Tue, 11 Mar 2014 19:01:43 -0700 (PDT)
Subject: Tuples and immutability
In-Reply-To: <mailman.7446.1393539531.18130.python-list@python.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
 <mailman.7446.1393539531.18130.python-list@python.org>
Message-ID: <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>


On Thursday, February 27, 2014 4:18:01 PM UTC-6, Ian wrote:
> x += y is meant to be equivalent, except possibly in-place and more
> efficient, than x = x + y.  

In an ideal world, the speed of these two codes should be the same, of course i'm "assuming" that most competent language designers would optimise the slower version. 

"""But Rick, Python is an interpreted language and does not benefit from a compile stage."""

Even if the bytecode can't be optimized on the current run, it CAN be optimized by updating the .pyo file for future runs without degrading current (or future) runtime performance.


From rosuav at gmail.com  Tue Mar 11 22:10:23 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 12 Mar 2014 13:10:23 +1100
Subject: Tuples and immutability
In-Reply-To: <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
 <mailman.7446.1393539531.18130.python-list@python.org>
 <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
Message-ID: <CAPTjJmqpbhO6qMHO5+mRJn6wMmL30neWtGankbwNqdHPtat=3g@mail.gmail.com>

On Wed, Mar 12, 2014 at 1:01 PM, Rick Johnson
<rantingrickjohnson at gmail.com> wrote:
> On Thursday, February 27, 2014 4:18:01 PM UTC-6, Ian wrote:
>> x += y is meant to be equivalent, except possibly in-place and more
>> efficient, than x = x + y.
>
> In an ideal world, the speed of these two codes should be the same, of course i'm "assuming" that most competent language designers would optimise the slower version.
>

Except that they don't mean the same thing, so it's not an optimization target.

ChrisA


From tjreedy at udel.edu  Tue Mar 11 23:25:19 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 11 Mar 2014 23:25:19 -0400
Subject: Tuples and immutability
In-Reply-To: <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
 <mailman.7446.1393539531.18130.python-list@python.org>
 <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
Message-ID: <lfok34$tvo$1@ger.gmane.org>

On 3/11/2014 10:01 PM, Rick Johnson wrote:
>
> On Thursday, February 27, 2014 4:18:01 PM UTC-6, Ian wrote:
>> x += y is meant to be equivalent, except possibly in-place and
>> more efficient, than x = x + y.

The manual actually says "An augmented assignment expression like x += 1 
can be rewritten as x = x + 1 to achieve a similar, but not exactly 
equal effect. In the augmented version, x is only evaluated once. Also, 
when possible, the actual operation is performed in-place, meaning that 
rather than creating a new object and assigning that to the target, the 
old object is modified instead.


> In an ideal world, the speed of these two codes should be the same,

Nope, 'similar' is not 'equivalent'. Evaluating x twice instead of once 
and possibly allocating a new object versus not take extra time. In a 
statement like "x.y.z[3*n+m] += 1", calculating the target dominates the 
time to increment, so this form should be nearly twice as fast.

-- 
Terry Jan Reedy



From tjreedy at udel.edu  Tue Mar 11 23:36:44 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 11 Mar 2014 23:36:44 -0400
Subject: unittest weirdness
In-Reply-To: <lfo1qj$3m3$1@reader1.panix.com>
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <lfo1qj$3m3$1@reader1.panix.com>
Message-ID: <lfokoh$3q3$1@ger.gmane.org>

On 3/11/2014 6:13 PM, John Gordon wrote:
> In <mailman.8062.1394573210.18130.python-list at python.org> Ethan Furman <ethan at stoneleaf.us> writes:
>
>>           if missing:
>>               raise ValueError('invoices %r missing from batch' % missing)
>
> It's been a while since I wrote test cases, but I recall using the assert*
> methods (assertEqual, assertTrue, etc.) instead of raising exceptions.
> Perhaps that's the issue?

Yes. I believe the methods all raise AssertionError on failure, and the 
test methods are wrapped with try:.. except AssertionError as err:

    if missing:
      raise ValueError('invoices %r missing from batch' % missing)

should be "assertEqual(missing, [], 'invoices missing from batch')" and 
if that fails, the non-empty list is printed along with the message.

-- 
Terry Jan Reedy



From steve at pearwood.info  Wed Mar 12 02:28:01 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 12 Mar 2014 06:28:01 GMT
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
 <mailman.7446.1393539531.18130.python-list@python.org>
 <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
 <mailman.8071.1394594751.18130.python-list@python.org>
Message-ID: <531ffe70$0$2923$c3e8da3$76491128@news.astraweb.com>

On Tue, 11 Mar 2014 23:25:19 -0400, Terry Reedy wrote:

> On 3/11/2014 10:01 PM, Rick Johnson wrote:
>>
>> On Thursday, February 27, 2014 4:18:01 PM UTC-6, Ian wrote:
>>> x += y is meant to be equivalent, except possibly in-place and more
>>> efficient, than x = x + y.
> 
> The manual actually says "An augmented assignment expression like x += 1
> can be rewritten as x = x + 1 to achieve a similar, but not exactly
> equal effect. In the augmented version, x is only evaluated once. Also,
> when possible, the actual operation is performed in-place, meaning that
> rather than creating a new object and assigning that to the target, the
> old object is modified instead.
> 
> 
>> In an ideal world, the speed of these two codes should be the same,
> 
> Nope, 'similar' is not 'equivalent'. Evaluating x twice instead of once
> and possibly allocating a new object versus not take extra time. In a
> statement like "x.y.z[3*n+m] += 1", calculating the target dominates the
> time to increment, so this form should be nearly twice as fast.

Excellent point Terry!

I always forget that the target of an augmented assignment may not be a 
simple name like "x" but can be an arbitrary complex reference, anything 
that is a legal assignment target. Because += is documented as only 
evaluating the expression once it can behave quite differently to the 
`spam = spam + 1` case. Evaluating the right hand side may have side-
effects that change what the left hand side evaluates to. This is not the 
case with the augmented assignment.

-- 
Steven


From ethan at stoneleaf.us  Wed Mar 12 02:32:53 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Tue, 11 Mar 2014 23:32:53 -0700
Subject: Tuples and immutability
In-Reply-To: <lfok34$tvo$1@ger.gmane.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
 <mailman.7446.1393539531.18130.python-list@python.org>
 <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
 <lfok34$tvo$1@ger.gmane.org>
Message-ID: <531FFF95.6050802@stoneleaf.us>

On 03/11/2014 08:25 PM, Terry Reedy wrote:
> On 3/11/2014 10:01 PM, Rick Johnson wrote:
>>
>> On Thursday, February 27, 2014 4:18:01 PM UTC-6, Ian wrote:
>>> x += y is meant to be equivalent, except possibly in-place and
>>> more efficient, than x = x + y.
>
> The manual actually says "An augmented assignment expression like x += 1 can be rewritten as x = x + 1 to achieve a
> similar, but not exactly equal effect. In the augmented version, x is only evaluated once. Also, when possible, the
> actual operation is performed in-place, meaning that rather than creating a new object and assigning that to the target,
> the old object is modified instead.

... and reassigned to the target.  :)  (If it doesn't say that last part, it should.)

--
~Ethan~


From __peter__ at web.de  Wed Mar 12 03:36:40 2014
From: __peter__ at web.de (Peter Otten)
Date: Wed, 12 Mar 2014 08:36:40 +0100
Subject: beautiful soup get class info
References: <e73d29eb-17bb-472e-bdc4-c38ca904c60f@googlegroups.com>
 <lfofai$9oc$1@ger.gmane.org>
Message-ID: <lfp2pr$b3o$1@ger.gmane.org>

Christopher Welborn wrote:

> On 03/06/2014 02:22 PM, teddybubu at gmail.com wrote:
>> I am using beautifulsoup to get the title and date of the website.
>> title is working fine but I am not able to pull the date. Here is the
>> code in the url:
>>
>>   <span class="date">October 22, 2011</span>
>>
>> In Python, I am using the following code:
>> date1 = soup.span.text
>> data=soup.find_all(date="value")
>>
>> Results in:
>>
>> []
>> March 5, 2014
>>
>> What is the proper way to get this info?
>> Thanks.
>>
> 
> I believe it's the 'attrs' argument.
> http://www.crummy.com/software/BeautifulSoup/bs4/doc/
> 
> # Workaround the 'class' problem:
> data = soup.find_all(attrs={'class': 'date'})
> 
> I haven't tested it, but it's worth looking into.
 
Yes there are two ways to filtr by class:

>>> soup = bs4.BeautifulSoup("""
... <span class="one">alpha</span>
... <span class="two">beta</span>""")

Use attrs:

>>> soup.find_all(attrs={"class": "one"})
[<span class="one">alpha</span>]

Append an underscore:

>>> soup.find_all(class_="two")
[<span class="two">beta</span>]




From antoon.pardon at rece.vub.ac.be  Wed Mar 12 05:08:48 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 12 Mar 2014 10:08:48 +0100
Subject: Balanced trees
In-Reply-To: <roy-F30152.19240710032014@news.panix.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <roy-F30152.19240710032014@news.panix.com>
Message-ID: <53202420.2040009@rece.vub.ac.be>

Op 11-03-14 00:24, Roy Smith schreef:

> In article <8761nmrnfk.fsf at elektro.pacujo.net>,
>  Marko Rauhamaa <marko at pacujo.net> wrote:
>
>> Anyway, this whole debate is rather unnecessary since every developer is
>> supposed to have both weapons in their arsenal.
> The problem with having a choice is that it opens up the possibility of 
> making the wrong one :-)

This is just a standard defense for the status quo. Introducing the decimal
module also added a choice.

> As this discussion has shown, figuring out whether a hash table or a 
> tree is better for a given problem is non-trivial.  My guess is that if 
> you gave 1000 typical developers both data structures and let them pick 
> freely, the number of cases where it really mattered and the developer 
> picked the right one would be approximately equal to the number of cases 
> where they picked the wrong one.

You are only illustrating one part. How about all those cases now where the
wrong choice is more or less forced on the developer for lack of the alternative?

-- 
Antoon Pardon



From antoon.pardon at rece.vub.ac.be  Wed Mar 12 05:39:35 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 12 Mar 2014 10:39:35 +0100
Subject: Tuples and immutability
In-Reply-To: <531ffe70$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
 <mailman.7446.1393539531.18130.python-list@python.org>
 <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
 <mailman.8071.1394594751.18130.python-list@python.org>
 <531ffe70$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <53202B57.7060504@rece.vub.ac.be>

Op 12-03-14 07:28, Steven D'Aprano schreef:
> On Tue, 11 Mar 2014 23:25:19 -0400, Terry Reedy wrote:
>
>> Nope, 'similar' is not 'equivalent'. Evaluating x twice instead of once
>> and possibly allocating a new object versus not take extra time. In a
>> statement like "x.y.z[3*n+m] += 1", calculating the target dominates the
>> time to increment, so this form should be nearly twice as fast.
> Excellent point Terry!
>
> I always forget that the target of an augmented assignment may not be a 
> simple name like "x" but can be an arbitrary complex reference, anything 
> that is a legal assignment target. Because += is documented as only 
> evaluating the expression once it can behave quite differently to the 
> `spam = spam + 1` case. Evaluating the right hand side may have side-
> effects that change what the left hand side evaluates to. This is not the 
> case with the augmented assignment.

The documentation is wrong at that point as the following code illustrates.

| import sys
| write = sys.stdout.write
|
| class logdict:
|     def __init__(self):
|         self.lst = {}
|
|     def __setitem__(self, key, value):
|         write('[%s] <= %s\n' % (key, value))
|         self.lst[key] = value
|
|     def __getitem__(self, key):
|         value = self.lst[key]
|         write('[%s] => %s\n' % (key, value))
|         return value
|
| tab = logdict()
| tab['key'] = 'value'
| tab['key'] += ' with extra tail'
| write('====\n')
| tab = logdict()
| tab['key'] = 'value'
| tab['key'] = tab['key'] + ' with extra tail'

If you run this code, you get the following result:

| [key] <= value
| [key] => value
| [key] <= value with extra tail
| ====
| [key] <= value
| [key] => value
| [key] <= value with extra tail

As you can see there is no difference here in the evaluations done
between using

| tab['key'] += ' with extra tail'

or

| tab['key'] = tab['key'] + ' with extra tail'


From ian.g.kelly at gmail.com  Wed Mar 12 05:40:29 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 12 Mar 2014 03:40:29 -0600
Subject: Tuples and immutability
In-Reply-To: <531ffe70$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
 <mailman.7446.1393539531.18130.python-list@python.org>
 <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
 <mailman.8071.1394594751.18130.python-list@python.org>
 <531ffe70$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CALwzidmA1+QP9sr8tOwvo9v70y01D8kxcn_0v1F-k8G-x=C6zw@mail.gmail.com>

On Wed, Mar 12, 2014 at 12:28 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Tue, 11 Mar 2014 23:25:19 -0400, Terry Reedy wrote:
>> Nope, 'similar' is not 'equivalent'. Evaluating x twice instead of once
>> and possibly allocating a new object versus not take extra time. In a
>> statement like "x.y.z[3*n+m] += 1", calculating the target dominates the
>> time to increment, so this form should be nearly twice as fast.
>
> Excellent point Terry!
>
> I always forget that the target of an augmented assignment may not be a
> simple name like "x" but can be an arbitrary complex reference, anything
> that is a legal assignment target. Because += is documented as only
> evaluating the expression once it can behave quite differently to the
> `spam = spam + 1` case. Evaluating the right hand side may have side-
> effects that change what the left hand side evaluates to. This is not the
> case with the augmented assignment.

Of course one could also do:

    z = x.y.z
    i = 3*n+m
    z[i] = z[i] + 1

which reduces the duplicated work down to storing and loading a couple
of locals, and also prevents side-effects from affecting the LHS
evaluation.


From ian.g.kelly at gmail.com  Wed Mar 12 05:51:52 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 12 Mar 2014 03:51:52 -0600
Subject: Tuples and immutability
In-Reply-To: <53202B57.7060504@rece.vub.ac.be>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
 <mailman.7446.1393539531.18130.python-list@python.org>
 <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
 <mailman.8071.1394594751.18130.python-list@python.org>
 <531ffe70$0$2923$c3e8da3$76491128@news.astraweb.com>
 <53202B57.7060504@rece.vub.ac.be>
Message-ID: <CALwzidkGxdboq-=+NktMk7fp=+EAZGtSOUEb=yPHyT85Xr+_tA@mail.gmail.com>

On Wed, Mar 12, 2014 at 3:39 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> The documentation is wrong at that point as the following code illustrates.

Either way it still has to do a getitem and a setitem, but if you have
a more nested structure then the extra getitems are not repeated.  For
example, using your logdict class:

>>> tab = logdict()
>>> tab[1] = logdict()
[1] <= <__main__.logdict object at 0x02A2E430>
>>> tab[1][2] = logdict()
[1] => <__main__.logdict object at 0x02A2E430>
[2] <= <__main__.logdict object at 0x02A2EB10>
>>> tab[1][2][3] = ['value']
[1] => <__main__.logdict object at 0x02A2E430>
[2] => <__main__.logdict object at 0x02A2EB10>
[3] <= ['value']
>>> tab[1][2][3] += [' with extra tail']
[1] => <__main__.logdict object at 0x02A2E430>
[2] => <__main__.logdict object at 0x02A2EB10>
[3] => ['value']
[3] <= ['value', ' with extra tail']

versus:

>>> tab[1][2][3] = ['value']
[1] => <__main__.logdict object at 0x02A2E430>
[2] => <__main__.logdict object at 0x02A2EB10>
[3] <= ['value']
>>> tab[1][2][3] = tab[1][2][3] + [' with extra tail']
[1] => <__main__.logdict object at 0x02A2E430>
[2] => <__main__.logdict object at 0x02A2EB10>
[3] => ['value']
[1] => <__main__.logdict object at 0x02A2E430>
[2] => <__main__.logdict object at 0x02A2EB10>
[3] <= ['value', ' with extra tail']

As you can see the += version does two fewer getitem calls in this case.


From ian.g.kelly at gmail.com  Wed Mar 12 05:58:50 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 12 Mar 2014 03:58:50 -0600
Subject: which async framework?
In-Reply-To: <CAPTjJmrRaM2tU_-k=W9JOG0YKSsnW_=z4OrXRQJxHcf9HTDUUg@mail.gmail.com>
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <loom.20140311T170030-477@post.gmane.org>
 <372076480416251284.821607sturla.molden-gmail.com@news.gmane.org>
 <mailman.8056.1394563452.18130.python-list@python.org>
 <877g80nzdx.fsf@elektro.pacujo.net>
 <mailman.8064.1394577523.18130.python-list@python.org>
 <87wqg0mihv.fsf@elektro.pacujo.net>
 <CAPTjJmrRaM2tU_-k=W9JOG0YKSsnW_=z4OrXRQJxHcf9HTDUUg@mail.gmail.com>
Message-ID: <CALwzid=15iH1vraSVSUSFbgFOytO1rW78_zeCRtH4RmaYK2SqA@mail.gmail.com>

On Tue, Mar 11, 2014 at 5:38 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Wed, Mar 12, 2014 at 10:18 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> Chris Angelico <rosuav at gmail.com>:
>>
>>> What corner cases are there with threads that you don't have with
>>> anything else?
>>
>> There are numerous. Here's one example: deadlocks due to two threads
>> taking locks in a different order. The problem crops up naturally with
>> two intercommunicating classes. It can sometimes be very difficult to
>> spot or avoid.
>
> Yep. Now how is that not a problem when you use some other model, like
> an event loop? The standard methods of avoiding deadlocks (like
> acquiring locks in strict order) work exactly the same for all models,
> and are just as necessary.

If you don't have threads then the only locks you need to acquire are
for external resources.  You might still deadlock, but at least your
process won't be deadlocking with itself.


From eras.rasmuson at gmail.com  Wed Mar 12 06:08:04 2014
From: eras.rasmuson at gmail.com (eras.rasmuson at gmail.com)
Date: Wed, 12 Mar 2014 03:08:04 -0700 (PDT)
Subject: SMTPHandler and mail subject
Message-ID: <4b23c949-12eb-444b-a950-c830ace83ca9@googlegroups.com>

Hi

I use logging.handlers.SMTPHandler and i have tried to change subject of mail.

Are there exists easy way to do that ?

Subject of mail can change repeatedly depends on content of mail.

----
Eras


From oscar.j.benjamin at gmail.com  Wed Mar 12 06:20:25 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Wed, 12 Mar 2014 10:20:25 +0000
Subject: Tuples and immutability
In-Reply-To: <lfok34$tvo$1@ger.gmane.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
 <mailman.7446.1393539531.18130.python-list@python.org>
 <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
 <lfok34$tvo$1@ger.gmane.org>
Message-ID: <CAHVvXxQfdZm40WWL4L9s=w8enOxJukpMSxAES_Bm_xWyb3LMpA@mail.gmail.com>

On 12 March 2014 03:25, Terry Reedy <tjreedy at udel.edu> wrote:
> On 3/11/2014 10:01 PM, Rick Johnson wrote:
>>
>>
>> On Thursday, February 27, 2014 4:18:01 PM UTC-6, Ian wrote:
>>>
>>> x += y is meant to be equivalent, except possibly in-place and
>>> more efficient, than x = x + y.
>
>
> The manual actually says "An augmented assignment expression like x += 1 can
> be rewritten as x = x + 1 to achieve a similar, but not exactly equal
> effect. In the augmented version, x is only evaluated once. Also, when
> possible, the actual operation is performed in-place, meaning that rather
> than creating a new object and assigning that to the target, the old object
> is modified instead.
>
>
>
>> In an ideal world, the speed of these two codes should be the same,
>
>
> Nope, 'similar' is not 'equivalent'. Evaluating x twice instead of once and
> possibly allocating a new object versus not take extra time. In a statement
> like "x.y.z[3*n+m] += 1", calculating the target dominates the time to
> increment, so this form should be nearly twice as fast.

An example where the result is semantically different:

>>> from numpy import array
>>> a = array([1, 2, 3], dtype=int)
>>> a
array([1, 2, 3])
>>> a + 1.1
array([ 2.1,  3.1,  4.1])
>>> a += 1.1
>>> a
array([2, 3, 4])

The reason is that numpy arrays are both mutable and have statically
determined elementary data type:

>>> (a + 1.1).dtype
dtype('float64')
>>> a.dtype
dtype('int64')


Oscar


From andriy.kornatskyy at live.com  Wed Mar 12 06:27:45 2014
From: andriy.kornatskyy at live.com (Andriy Kornatskyy)
Date: Wed, 12 Mar 2014 12:27:45 +0200
Subject: SMTPHandler and mail subject
In-Reply-To: <4b23c949-12eb-444b-a950-c830ace83ca9@googlegroups.com>
References: <4b23c949-12eb-444b-a950-c830ace83ca9@googlegroups.com>
Message-ID: <BLU0-SMTP115D7FB482D272CB04A222F91760@phx.gbl>

Eras,

You have to override getSubject method of SMTPHandler.

http://hg.python.org/cpython/file/677327810121/Lib/logging/handlers.py#l907

Thanks.

Andriy Kornatskyy

On Mar 12, 2014, at 12:08 PM, eras.rasmuson at gmail.com wrote:

> Hi
> 
> I use logging.handlers.SMTPHandler and i have tried to change subject of mail.
> 
> Are there exists easy way to do that ?
> 
> Subject of mail can change repeatedly depends on content of mail.
> 
> ----
> Eras
> -- 
> https://mail.python.org/mailman/listinfo/python-list



From ethan at stoneleaf.us  Wed Mar 12 06:03:24 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Wed, 12 Mar 2014 03:03:24 -0700
Subject: unittest weirdness
In-Reply-To: <lfokoh$3q3$1@ger.gmane.org>
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <lfo1qj$3m3$1@reader1.panix.com> <lfokoh$3q3$1@ger.gmane.org>
Message-ID: <532030EC.7000204@stoneleaf.us>

On 03/11/2014 08:36 PM, Terry Reedy wrote:
> On 3/11/2014 6:13 PM, John Gordon wrote:
>> In <mailman.8062.1394573210.18130.python-list at python.org> Ethan Furman <ethan at stoneleaf.us> writes:
>>
>>>           if missing:
>>>               raise ValueError('invoices %r missing from batch' % missing)
>>
>> It's been a while since I wrote test cases, but I recall using the assert*
>> methods (assertEqual, assertTrue, etc.) instead of raising exceptions.
>> Perhaps that's the issue?
>
> Yes. I believe the methods all raise AssertionError on failure, and the test methods are wrapped with try:.. except
> AssertionError as err:
>
>     if missing:
>       raise ValueError('invoices %r missing from batch' % missing)
>
> should be "assertEqual(missing, [], 'invoices missing from batch')" and if that fails, the non-empty list is printed
> along with the message.

I've tried it both ways, and both ways my process is being killed, presumably by the O/S.

I will say it's an extra motivating factor to have few failing tests -- if more than two of my tests fail, all I see are 
'.'s, 'E's, and 'F's, with no clues as to which test failed nor why.  Thank goodness for '-v' and being able to specify 
which method of which class to run!

--
~Ethan~


From ndbecker2 at gmail.com  Wed Mar 12 07:16:23 2014
From: ndbecker2 at gmail.com (Neal Becker)
Date: Wed, 12 Mar 2014 07:16:23 -0400
Subject: which async framework?
References: <531E22DF.7030709@simplistix.co.uk>
 <1733040935416225908.878896sturla.molden-gmail.com@news.gmane.org>
 <mailman.8049.1394553908.18130.python-list@python.org>
 <lfnf02$q0c$1@reader1.panix.com>
Message-ID: <lfpflp$sto$1@ger.gmane.org>

Grant Edwards wrote:

> On 2014-03-11, Antoine Pitrou <solipsis at pitrou.net> wrote:
>> Sturla Molden <sturla.molden <at> gmail.com> writes:
>>> 
>>> Chris Withers <chris <at> simplistix.co.uk> wrote:
>>> > Hi All,
>>> > 
>>> > I see python now has a plethora of async frameworks and I need to try
>>> > and pick one to use from:
>>> > 
>>> > - asyncio/tulip
>>> > - tornado
>>> > - twisted
>>> 
>>> I'd go for using iocp, epoll and kqueue/kevent directly. Why bother to
>>> learn a framework? You will find epoll and kqueue/kevent in the select
>>> module and iocp in pywin32.
>>
>> Yes, why use a library when you can rewrite it all yourself?
>> Actually, you should probably issue system calls to the kernel directly,
>> the libc is overrated (as is portability, I suppose).
> 
> And don't bother with device drivers for the network adapters either.
> Just map their PCI regions in to user-space and twiddle the reigisters
> directly!  ;)
> 
> [I do that when testing PCI boards with C code, and one of these days
> I'm going to figure out how to do it with Python.]
> 

Use numpy with mmap



From antoon.pardon at rece.vub.ac.be  Wed Mar 12 07:21:05 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 12 Mar 2014 12:21:05 +0100
Subject: Tuples and immutability
In-Reply-To: <CALwzidkGxdboq-=+NktMk7fp=+EAZGtSOUEb=yPHyT85Xr+_tA@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <mailman.7427.1393517631.18130.python-list@python.org>
 <lenp14$m8f$1@cabale.usenet-fr.net>
 <CAPTjJmrdd+yxnfyBqO45pZfx8hFyWxOeEkx9zgdm842x-qhF+g@mail.gmail.com>
 <CAHkxivfZjqNa2hCbQiyPLSvJ=VBy7nstj3caA2Yu0NUBKR9AHg@mail.gmail.com>
 <mailman.7446.1393539531.18130.python-list@python.org>
 <0d76f320-a39e-44e9-85a2-74220b646566@googlegroups.com>
 <mailman.8071.1394594751.18130.python-list@python.org>
 <531ffe70$0$2923$c3e8da3$76491128@news.astraweb.com>
 <53202B57.7060504@rece.vub.ac.be>
 <CALwzidkGxdboq-=+NktMk7fp=+EAZGtSOUEb=yPHyT85Xr+_tA@mail.gmail.com>
Message-ID: <53204321.9050904@rece.vub.ac.be>

Op 12-03-14 10:51, Ian Kelly schreef:
> On Wed, Mar 12, 2014 at 3:39 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> The documentation is wrong at that point as the following code illustrates.
> Either way it still has to do a getitem and a setitem, but if you have
> a more nested structure then the extra getitems are not repeated.  For
> example, using your logdict class:

Sure, but the documentation doesn't say for sufficiently nested structures
some evaluations are not repeated.

Take the following example.

| tab['key'] = [1]
| tab['key'] += [2]

Now let us rewrite that second statment in two different ways.

| tab['key'] = tab['key'] + [2]

or

| tmp = tab['key']
| tmp += [2]

Now which of these two rewritings is closer to the augmented concatenation?
A natural reading of the documentation would conclude the second one, because
in that case we only need to evaluate tab['key'] once as righthand sided.
However it turns out the augmented concantenation is closer to the first
rewriting here, evaluating tab['key'] twice once a lefthand sided and once
as right hand sided, which IMO will surprise people that rely on the documentation.

-- 
Antoon Pardon



From fomcl at yahoo.com  Wed Mar 12 08:22:59 2014
From: fomcl at yahoo.com (Albert-Jan Roskam)
Date: Wed, 12 Mar 2014 05:22:59 -0700 (PDT)
Subject: locale getlocale returns None on OSX
Message-ID: <1394626979.46880.YahooMailBasic@web163806.mail.gq1.yahoo.com>

Hi,

locale.getlocale() sometimes returns (None, None) under OSX (Python 2, not sure about Python 3, but I think so). The problem is outlined here:
http://stackoverflow.com/questions/1629699/locale-getlocale-problems-on-osx

What is the cause of this? Is it limited to just Darwin systes? Does the 'horrible hack' solution on OS have any drawbacks? I like it better because it is not needed to set the LC_ALL environment variable prior to starting the Python program.

Regards,

Albert-Jan



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a 

fresh water system, and public health, what have the Romans ever done for us?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



From eras.rasmuson at gmail.com  Wed Mar 12 08:25:35 2014
From: eras.rasmuson at gmail.com (eras.rasmuson at gmail.com)
Date: Wed, 12 Mar 2014 05:25:35 -0700 (PDT)
Subject: SMTPHandler and mail subject
In-Reply-To: <mailman.8081.1394620139.18130.python-list@python.org>
References: <4b23c949-12eb-444b-a950-c830ace83ca9@googlegroups.com>
 <mailman.8081.1394620139.18130.python-list@python.org>
Message-ID: <f92d95e9-8997-4040-a8b8-d2404fe04798@googlegroups.com>


It works. Thank you :)

----
Eras


From zoom at yahoo.com  Wed Mar 12 08:29:49 2014
From: zoom at yahoo.com (zoom)
Date: Wed, 12 Mar 2014 13:29:49 +0100
Subject: Save to a file, but avoid overwriting an existing file
Message-ID: <lfpjv9$tki$1@news1.carnet.hr>

Hi!

I would like to assure that when writing to a file I do not overwrite an 
existing file, but I'm unsure which is the best way to approach to this 
problem. As I can see, there are at least two possibilities:

1. I could use fd = os.open("x", os.O_WRONLY | os.O_CREAT | os.O_EXCL)
which will fail - if the file exists. However, I would prefer if the 
program would try to save under different name in this case, instead of 
discarding all the calculation done until now - but I' not too well with 
catching exceptions.

2. Alternatively, a unique string could be generated to assure that no 
same file exists. I can see one approach to this is to include date and 
time in the file name. But this seems to me a bit clumsy, and is not 
unique, i.e. it could happen (at least in theory) that two processes 
finish in the same second.

Any suggestions, please?


From skip at pobox.com  Wed Mar 12 08:37:44 2014
From: skip at pobox.com (Skip Montanaro)
Date: Wed, 12 Mar 2014 07:37:44 -0500
Subject: Save to a file, but avoid overwriting an existing file
In-Reply-To: <lfpjv9$tki$1@news1.carnet.hr>
References: <lfpjv9$tki$1@news1.carnet.hr>
Message-ID: <CANc-5UyCL3JiuffvW=osFMNvXxg0Fgsm-eQ2P2swSVJq0gcZOw@mail.gmail.com>

This seems to be an application-level decision. If so, in your
application, why not just check to see if the file exists, and
implement whatever workaround you deem correct for your needs? For
example (to choose a simple, but rather silly, file naming strategy):

fname = "x"
while os.path.exists(fname):
    fname = "%s.%f" % (fname, random.random())
fd = open(fname, "w")

It's clearly not going to be safe from race conditions, but I leave
solving that problem as an exercise for the reader.

Skip


From 114piyush at gmail.com  Wed Mar 12 09:09:27 2014
From: 114piyush at gmail.com (Piyush Verma)
Date: Wed, 12 Mar 2014 18:39:27 +0530
Subject: How do we pass default argument value to create thread object?
Message-ID: <CAJV9OM_9tg5y5cC_zrzSZ4RVF8VvxqOxE-uhzyKusWPeeC1sxg@mail.gmail.com>

Hi,

I am using Thread class to create threads.
<CODE>
thread = threading.Thread(target=Fun, args=[arg1, arg2, arg3="val"])
thread.start()
</CODE>

This code is throwing compilation error(Ipython).
In [19]: import threading

In [20]: def Fun(agr1, arg2, arg3=None):
   ....:     pass
   ....:

In [21]: thread = threading.Thread(target=Fun, args=[arg1, arg2, arg3="val"
])
------------------------------------------------------------
   File "<ipython console>", line 1
     thread = threading.Thread(target=Fun, args=[arg1, arg2, arg3="val"])
                                                                 ^
SyntaxError: invalid syntax

How do we pass the value to default arguments while creating thread object?

Regards,
~Piyush
Facebook <https://www.facebook.com/piyushkv1>
Twitter<https://twitter.com/SocializePiyush>
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From python.list at tim.thechases.com  Wed Mar 12 09:33:06 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Wed, 12 Mar 2014 08:33:06 -0500
Subject: Save to a file, but avoid overwriting an existing file
In-Reply-To: <lfpjv9$tki$1@news1.carnet.hr>
References: <lfpjv9$tki$1@news1.carnet.hr>
Message-ID: <20140312083306.4111c5bd@bigbox.christie.dr>

On 2014-03-12 13:29, zoom wrote:
> 2. Alternatively, a unique string could be generated to assure that
> no same file exists. I can see one approach to this is to include
> date and time in the file name. But this seems to me a bit clumsy,
> and is not unique, i.e. it could happen (at least in theory) that
> two processes finish in the same second.

Python offers a "tempfile" module that gives this (and a whole lot
more) to you out of the box.

-tkc








From roy at panix.com  Wed Mar 12 09:44:47 2014
From: roy at panix.com (Roy Smith)
Date: Wed, 12 Mar 2014 09:44:47 -0400
Subject: unittest weirdness
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <lfo1qj$3m3$1@reader1.panix.com> <lfokoh$3q3$1@ger.gmane.org>
 <mailman.8082.1394620172.18130.python-list@python.org>
Message-ID: <roy-66F336.09444712032014@news.panix.com>

In article <mailman.8082.1394620172.18130.python-list at python.org>,
 Ethan Furman <ethan at stoneleaf.us> wrote:

> I've tried it both ways, and both ways my process is being killed, presumably 
> by the O/S.

What evidence do you have the OS is killing the process?

Some systems have an oom (Out Of Memory) process killer, which nukes 
(semi-random) process when the system exhausts memory.  Is it possible 
this is happening?  If so, you should see some log message in one of 
your system logs.

You didn't mention (or maybe I misssed it) which OS you're using.  I'm 
assuming you've got some kind of system call tracer (strace, truss, 
dtrace, etc).  Try running your tests under that.  If something is 
sending your process a kill signal, you'll see it:

[gazillions of lines elided]
write(1, ">>> ", 4>>> )                     = 4
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
select(1, [0], NULL, NULL, NULL)        = ? ERESTARTNOHAND (To be 
restarted)
--- SIGTERM (Terminated) @ 0 (0) ---
+++ killed by SIGTERM +++

Alternatively, maybe something inside your process is just calling 
sys.exit(), or even os._exit().  You'll see the exit() system call in 
the strace output.

And, of course, the standard suggestion to reduce this down to the 
minimum test case.  You posted:

     def test_xxx_1(self):
         p = self.pp.lockbox_payments[0]
         # affirm we have what we're expecting
         self.assertEqual(
                 (p.payer, p.ck_num, p.credit),
                 ('a customer', '010101', 10000),
                 )
         self.assertEqual(p.invoices.keys(), ['XXXXXXXXXXX'])
         self.assertEqual(p.invoices.values()[0].amount, 10000)
         # now make sure we get back what we're expecting
         np, b = self.pp._match_invoices(p)
         missing = []
         for inv_num in ('123456', '789012', '345678'):
             if inv_num not in b:
                 missing.append(inv_num)
         if missing:
             raise ValueError('invoices %r missing from batch' % missing)

what happens if you reduce that to:

     def test_xxx_1(self):
          self.fail()

do you still get this strange behavior?  What if you get rid of your 
setUpClass()?  Keep hacking away at the test suite until you get down to 
a single line of code which, if run, exhibits the behavior, and if 
commented out, does not.  At that point, you'll have a clue what's 
causing this.  If you're lucky :-)


From jeanmichel at sequans.com  Wed Mar 12 09:51:15 2014
From: jeanmichel at sequans.com (Jean-Michel Pichavant)
Date: Wed, 12 Mar 2014 14:51:15 +0100 (CET)
Subject: How do we pass default argument value to create thread object?
In-Reply-To: <CAJV9OM_9tg5y5cC_zrzSZ4RVF8VvxqOxE-uhzyKusWPeeC1sxg@mail.gmail.com>
Message-ID: <1105316214.7314008.1394632275305.JavaMail.root@sequans.com>


----- Original Message ----- 

> Hi,

> I am using Thread class to create threads.
> <CODE>
> thread = threading.Thread(target=Fun, args=[arg1, arg2, arg3="val"])
> thread.start()
> </CODE>

> This code is throwing compilation error(Ipython).

> In [19]: import threading

> In [20]: def Fun(agr1, arg2, arg3=None):
> ....: pass
> ....:

> In [21]: thread = threading.Thread(target=Fun, args=[arg1, arg2,
> arg3="val" ])
> ------------------------------------------------------------
> File "<ipython console>", line 1
> thread = threading.Thread(target=Fun, args=[arg1, arg2, arg3="val"])
> ^
> SyntaxError: invalid syntax

> How do we pass the value to default arguments while creating thread
> object?

> Regards,
> ~Piyush
> Facebook Twitter

Hi,

try something like

thread = threading.Thread(target=Fun, args=("val1", "val2"), kwargs={"arg3":"val3"})

This will call
Fun("val1", "val2", arg3="val3")

Browse the python tutorial for details on arguments and keyword arguments.

Cheers,

JM


-- IMPORTANT NOTICE: 

The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

From zachary.ware+pylist at gmail.com  Wed Mar 12 10:12:39 2014
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Wed, 12 Mar 2014 09:12:39 -0500
Subject: How do we pass default argument value to create thread object?
In-Reply-To: <CAJV9OM_9tg5y5cC_zrzSZ4RVF8VvxqOxE-uhzyKusWPeeC1sxg@mail.gmail.com>
References: <CAJV9OM_9tg5y5cC_zrzSZ4RVF8VvxqOxE-uhzyKusWPeeC1sxg@mail.gmail.com>
Message-ID: <CAKJDb-NFNcwA1EJuyksukXu0oLpd=k=OaSaKNwaJGDR8EmPUPA@mail.gmail.com>

On Wed, Mar 12, 2014 at 8:09 AM, Piyush Verma <114piyush at gmail.com> wrote:
> Hi,
>
> I am using Thread class to create threads.
> <CODE>
> thread = threading.Thread(target=Fun, args=[arg1, arg2, arg3="val"])
> thread.start()
> </CODE>
>
> This code is throwing compilation error(Ipython).
> In [19]: import threading
>
> In [20]: def Fun(agr1, arg2, arg3=None):
>    ....:     pass
>    ....:
>
> In [21]: thread = threading.Thread(target=Fun, args=[arg1, arg2,
> arg3="val"])
> ------------------------------------------------------------
>    File "<ipython console>", line 1
>      thread = threading.Thread(target=Fun, args=[arg1, arg2, arg3="val"])
>                                                                  ^
> SyntaxError: invalid syntax
>
> How do we pass the value to default arguments while creating thread object?

Use the 'kwargs' argument:

   thread = threading.Thread(target=Fun, args=[1, 2], kwargs={'arg3': "val"})

See http://docs.python.org/3.4/library/threading#threading.Thread for more info.

Hope this helps,
-- 
Zach


From zdoor at xs4all.nl  Wed Mar 12 10:25:46 2014
From: zdoor at xs4all.nl (Alex van der Spek)
Date: 12 Mar 2014 14:25:46 GMT
Subject: Deep vs. shallow copy?
Message-ID: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>

I think I understand the difference between deep vs. shallow copies but 
I was bitten by this:

with open(os.path.join('path', 'foo.txt', 'rb') as txt:
     reader = csv.reader(txt)
     data = [row.append(year) for row in reader]

This does not work although the append does complete. The below works:

with open(os.path.join('path', 'foo.txt', 'rb') as txt:
     reader = csv.reader(txt)
     data = [row + [year] for row in reader]

However in this context I am baffled. If someone can explain what is 
going on here, I would be most grateful.

Alex van der Spek


From skip at pobox.com  Wed Mar 12 10:48:38 2014
From: skip at pobox.com (Skip Montanaro)
Date: Wed, 12 Mar 2014 09:48:38 -0500
Subject: Deep vs. shallow copy?
In-Reply-To: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
Message-ID: <CANc-5UzYD9gPv0wSKHLNQ19p2N-2VQMtNh5hK0D_g5EsziZ52Q@mail.gmail.com>

On Wed, Mar 12, 2014 at 9:25 AM, Alex van der Spek <zdoor at xs4all.nl> wrote:
> with open(os.path.join('path', 'foo.txt', 'rb') as txt:
>      reader = csv.reader(txt)
>      data = [row.append(year) for row in reader]

Forget deep v. shallow copies. What is the value of the variable year?
And why would you expect list.append to return anything?

Skip


From zachary.ware+pylist at gmail.com  Wed Mar 12 11:00:09 2014
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Wed, 12 Mar 2014 10:00:09 -0500
Subject: Deep vs. shallow copy?
In-Reply-To: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
Message-ID: <CAKJDb-O5dwvgPm1YkKHCUMyrVhBndVTLdK1Qj=8KiRteJpEkqg@mail.gmail.com>

On Wed, Mar 12, 2014 at 9:25 AM, Alex van der Spek <zdoor at xs4all.nl> wrote:
> I think I understand the difference between deep vs. shallow copies but
> I was bitten by this:
>
> with open(os.path.join('path', 'foo.txt', 'rb') as txt:
>      reader = csv.reader(txt)
>      data = [row.append(year) for row in reader]
>
> This does not work although the append does complete. The below works:
>
> with open(os.path.join('path', 'foo.txt', 'rb') as txt:
>      reader = csv.reader(txt)
>      data = [row + [year] for row in reader]
>
> However in this context I am baffled. If someone can explain what is
> going on here, I would be most grateful.

Deep/shallow copying doesn't really come into this.  row.append()
mutates the list (row), it doesn't return a new list.  Like most
in-place/mutating methods in Python, it returns None instead of self
to show that mutation was done, so your listcomp fills `data` with
Nones; there is no copying done at all.  The second example works as
you expected because `row + [year]` results in a new list, which the
listcomp is happy to append to `data`--which does mean that `row` is
copied.

To avoid the copy that the second listcomp is doing (which really
shouldn't be necessary anyway, unless your rows are astronomically
huge), you have a couple of options.  First, you can expand your
listcomp and use append:

   with open(os.path.join('path', 'foo.txt'), 'rb') as txt: # with
your typo fixed ;)
       reader = csv.reader(txt)
       data = []
       for row in reader:
           row.append(year)
           data.append(row)

To me, that's pretty readable and pretty clear about what it's doing.
Then there's this option, which I don't recommend:

   import operator
   with open(os.path.join('path', 'foo.txt'), 'rb') as txt:
       reader = csv.reader(txt)
       data = [operator.iadd(row, [year]) for row in reader]

This works because operator.iadd is basically shorthand for
row.__iadd__([year]), which does return self (otherwise, the
assignment part of `row += [year]` couldn't work).  But, it's not as
clear about what's happening, and only saves a whole two lines (maybe
3 if you already have operator imported).

Hope this helps,
-- 
Zach


From zdoor at xs4all.nl  Wed Mar 12 11:29:59 2014
From: zdoor at xs4all.nl (Alex van der Spek)
Date: 12 Mar 2014 15:29:59 GMT
Subject: Deep vs. shallow copy?
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
Message-ID: <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>

On Wed, 12 Mar 2014 10:00:09 -0500, Zachary Ware wrote:

> On Wed, Mar 12, 2014 at 9:25 AM, Alex van der Spek <zdoor at xs4all.nl>
> wrote:
>> I think I understand the difference between deep vs. shallow copies but
>> I was bitten by this:
>>
>> with open(os.path.join('path', 'foo.txt', 'rb') as txt:
>>      reader = csv.reader(txt)
>>      data = [row.append(year) for row in reader]
>>
>> This does not work although the append does complete. The below works:
>>
>> with open(os.path.join('path', 'foo.txt', 'rb') as txt:
>>      reader = csv.reader(txt)
>>      data = [row + [year] for row in reader]
>>
>> However in this context I am baffled. If someone can explain what is
>> going on here, I would be most grateful.
> 
> Deep/shallow copying doesn't really come into this.  row.append()
> mutates the list (row), it doesn't return a new list.  Like most
> in-place/mutating methods in Python, it returns None instead of self to
> show that mutation was done, so your listcomp fills `data` with Nones;
> there is no copying done at all.  The second example works as you
> expected because `row + [year]` results in a new list, which the
> listcomp is happy to append to `data`--which does mean that `row` is
> copied.
> 
> To avoid the copy that the second listcomp is doing (which really
> shouldn't be necessary anyway, unless your rows are astronomically
> huge), you have a couple of options.  First, you can expand your
> listcomp and use append:
> 
>    with open(os.path.join('path', 'foo.txt'), 'rb') as txt: # with
> your typo fixed ;)
>        reader = csv.reader(txt)
>        data = []
>        for row in reader:
>            row.append(year)
>            data.append(row)
> 
> To me, that's pretty readable and pretty clear about what it's doing.
> Then there's this option, which I don't recommend:
> 
>    import operator
>    with open(os.path.join('path', 'foo.txt'), 'rb') as txt:
>        reader = csv.reader(txt)
>        data = [operator.iadd(row, [year]) for row in reader]
> 
> This works because operator.iadd is basically shorthand for
> row.__iadd__([year]), which does return self (otherwise, the assignment
> part of `row += [year]` couldn't work).  But, it's not as clear about
> what's happening, and only saves a whole two lines (maybe 3 if you
> already have operator imported).
> 
> Hope this helps,

Thank you, that helped immensely! 

Having been taught programming in Algol60 Python still defeats me at times!
Particularly since Algol60 wasn't very long lived and what came
thereafter (FORTRAN) much worse.

I get it now, the below is equivalent! 

I am perfectly happy with the one copy of the list row + [year]. 
Just wanted to learn something here and I have!


Python 2.6.5 (r265:79063, Feb 27 2014, 19:44:14) 
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> a = [1,2,3]
>>> b = 'val'
>>> a.append(b)
>>> a
[1, 2, 3, 'val']
>>> c = a.append(b)
>>> print c
None
>>> 



From ethan at stoneleaf.us  Wed Mar 12 11:32:29 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Wed, 12 Mar 2014 08:32:29 -0700
Subject: unittest weirdness
In-Reply-To: <roy-66F336.09444712032014@news.panix.com>
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <lfo1qj$3m3$1@reader1.panix.com> <lfokoh$3q3$1@ger.gmane.org>
 <mailman.8082.1394620172.18130.python-list@python.org>
 <roy-66F336.09444712032014@news.panix.com>
Message-ID: <53207E0D.2060604@stoneleaf.us>

On 03/12/2014 06:44 AM, Roy Smith wrote:
> In article <mailman.8082.1394620172.18130.python-list at python.org>,
>   Ethan Furman <ethan at stoneleaf.us> wrote:
>
>> I've tried it both ways, and both ways my process is being killed, presumably
>> by the O/S.
>
> What evidence do you have the OS is killing the process?

I put a bare try/except around the call to unittest.main, with a print statement in the except, and nothing ever prints.


> Some systems have an oom (Out Of Memory) process killer, which nukes
> (semi-random) process when the system exhausts memory.  Is it possible
> this is happening?  If so, you should see some log message in one of
> your system logs.

That would explain why my editor windows were being killed.


> You didn't mention (or maybe I misssed it) which OS you're using.

Ubuntu 13 something or other.

> I'm
> assuming you've got some kind of system call tracer (strace, truss,
> dtrace, etc).

Sadly, I have no experience with those programs yet, and until now didn't even know they existed.

> Try running your tests under that.  If something is
> sending your process a kill signal, you'll see it:
>
> [gazillions of lines elided]
> write(1, ">>> ", 4>>> )                     = 4
> rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
> select(1, [0], NULL, NULL, NULL)        = ? ERESTARTNOHAND (To be
> restarted)
> --- SIGTERM (Terminated) @ 0 (0) ---
> +++ killed by SIGTERM +++
>
> Alternatively, maybe something inside your process is just calling
> sys.exit(), or even os._exit().  You'll see the exit() system call in
> the strace output.

My bare try/except would have caught that.


> And, of course, the standard suggestion to reduce this down to the
> minimum test case.  You posted:
>
>       def test_xxx_1(self):
>           p = self.pp.lockbox_payments[0]
>           # affirm we have what we're expecting
>           self.assertEqual(
>                   (p.payer, p.ck_num, p.credit),
>                   ('a customer', '010101', 10000),
>                   )
>           self.assertEqual(p.invoices.keys(), ['XXXXXXXXXXX'])
>           self.assertEqual(p.invoices.values()[0].amount, 10000)
>           # now make sure we get back what we're expecting
>           np, b = self.pp._match_invoices(p)
>           missing = []
>           for inv_num in ('123456', '789012', '345678'):
>               if inv_num not in b:
>                   missing.append(inv_num)
>           if missing:
>               raise ValueError('invoices %r missing from batch' % missing)
>
> what happens if you reduce that to:
>
>       def test_xxx_1(self):
>            self.fail()

I only get the strange behavior if more than two (or maybe three) of my test cases fail.  Less than that magic number, 
and everything works just fine.  It doesn't matter which two or three, either.


> do you still get this strange behavior?  What if you get rid of your
> setUpClass()?  Keep hacking away at the test suite until you get down to
> a single line of code which, if run, exhibits the behavior, and if
> commented out, does not.  At that point, you'll have a clue what's
> causing this.  If you're lucky :-)

I strongly suspect it's memory.  When I originally wrote the code I tried to include six months worth of EoM data, but 
had to back it down to three as my process kept mysteriously dying at four or more months.  There must be waaaaaaay too 
much stuff being kept alive by the stack traces of the failed tests.

Thanks for your help!

--
~Ethan~


From stefan_ml at behnel.de  Wed Mar 12 13:10:03 2014
From: stefan_ml at behnel.de (Stefan Behnel)
Date: Wed, 12 Mar 2014 18:10:03 +0100
Subject: How to create an instance of a python class from C++
In-Reply-To: <8AEE6BCA-0F61-4F9E-A18B-13DB283DC134@barrys-emacs.org>
References: <0ab424e9-3a3f-4111-9f41-ff50ce73d70d@googlegroups.com>
 <8AEE6BCA-0F61-4F9E-A18B-13DB283DC134@barrys-emacs.org>
Message-ID: <lfq4cs$l2d$1@ger.gmane.org>

Barry Scott, 11.03.2014 22:37:
> On 5 Mar 2014, at 00:14, Bill wrote:
>> I can't figure out how to create an instance
>> of a python class from 'C++':
> 
> Why not use pycxx from http://sourceforge.net/projects/cxx/?
> 
> This lib does all the heavy lifting for you for both python2 and python3.
> Has docs and examples.

Yes, tool support definitely helps here. I was going to suggest Cython
(also for obvious reasons), where the code that the OP posted would look
like this:

  def RegisterClass(class_decl):
      an = type(class_decl)()
      print(an.description())
      return 0

Clearly substantially simpler than the posted C code (and certainly safer,
faster and more correct) - although that doesn't really help me much with
understanding what the intention of this code is, looks rather weird...

Stefan




From roy at panix.com  Wed Mar 12 13:48:46 2014
From: roy at panix.com (Roy Smith)
Date: Wed, 12 Mar 2014 13:48:46 -0400
Subject: unittest weirdness
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <lfo1qj$3m3$1@reader1.panix.com> <lfokoh$3q3$1@ger.gmane.org>
 <mailman.8082.1394620172.18130.python-list@python.org>
 <roy-66F336.09444712032014@news.panix.com>
 <mailman.8095.1394640002.18130.python-list@python.org>
Message-ID: <roy-F60364.13484512032014@news.panix.com>

In article <mailman.8095.1394640002.18130.python-list at python.org>,
 Ethan Furman <ethan at stoneleaf.us> wrote:

> > Alternatively, maybe something inside your process is just calling
> > sys.exit(), or even os._exit().  You'll see the exit() system call in
> > the strace output.
> 
> My bare try/except would have caught that.

A bare except would catch sys.exit(), but not os._exit().  Well, no 
that's not actually true.  Calling os._exit() will raise:

TypeError: _exit() takes exactly 1 argument (0 given)

but it won't catch os._exit(0) :-)

> > what happens if you reduce that to:
> >
> >       def test_xxx_1(self):
> >            self.fail()
> 
> I only get the strange behavior if more than two (or maybe three) of my test 
> cases fail.  Less than that magic number, 
> and everything works just fine.  It doesn't matter which two or three, 
> either.

OK, well, assuming this is a memory problem, what if you do:

      def test_xxx_1(self):
           l = []
           while True:
               l.append(0)

That should eventually run out of memory.  Does that get you the same 
behavior in a single test case?  If so, that at least would be evidence 
supporting the memory exhaustion theory.

> I strongly suspect it's memory.  When I originally wrote the code I tried to 
> include six months worth of EoM data, but 
> had to back it down to three as my process kept mysteriously dying at four or 
> more months.  There must be waaaaaaay too 
> much stuff being kept alive by the stack traces of the failed tests.

One thing you might try is running your tests under nose 
(http://nose.readthedocs.org/).  Nose knows how to run unittest tests, 
and one of the gazillion options it has is to run each test case in an 
isolated process:

  --process-restartworker
                If set, will restart each worker process once their
                tests are done, this helps control memory leaks from
                killing the system. [NOSE_PROCESS_RESTARTWORKER]

that might be what you need.


From davea at davea.name  Wed Mar 12 14:22:51 2014
From: davea at davea.name (Dave Angel)
Date: Wed, 12 Mar 2014 14:22:51 -0400 (EDT)
Subject: Save to a file, but avoid overwriting an existing file
References: <lfpjv9$tki$1@news1.carnet.hr>
Message-ID: <lfq8cr$tpj$1@ger.gmane.org>

 zoom <zoom at yahoo.com> Wrote in message:
> Hi!
> 
> I would like to assure that when writing to a file I do not overwrite an 
> existing file, but I'm unsure which is the best way to approach to this 
> problem. As I can see, there are at least two possibilities:
> 
> 1. I could use fd = os.open("x", os.O_WRONLY | os.O_CREAT | os.O_EXCL)
> which will fail - if the file exists. However, I would prefer if the 
> program would try to save under different name in this case, instead of 
> discarding all the calculation done until now - but I' not too well with 
> catching exceptions.
> 

The tempfile module is your best answer,  but if you really need
 to keep the file afterwards,  you'll have the same problem when
 you rename it later. 

I suggest you learn about try/except.  For simple cases it's not
 that tough, though if you want to ask about it, you'll need to
 specify your Python version. 

-- 
DaveA



From wbrehaut at mcsnet.ca  Wed Mar 12 15:06:38 2014
From: wbrehaut at mcsnet.ca (Wayne Brehaut)
Date: Wed, 12 Mar 2014 13:06:38 -0600
Subject: Deep vs. shallow copy?
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
Message-ID: <akb1i994eequ1amumqv6ilbrm82vpiacr5@4ax.com>

On 12 Mar 2014 15:29:59 GMT, Alex van der Spek <zdoor at xs4all.nl>
wrote:

>On Wed, 12 Mar 2014 10:00:09 -0500, Zachary Ware wrote:
>
>> On Wed, Mar 12, 2014 at 9:25 AM, Alex van der Spek <zdoor at xs4all.nl>
>> wrote:

=== 8< ===

>Having been taught programming in Algol60 Python still defeats me at times!
>Particularly since Algol60 wasn't very long lived and what came
>thereafter (FORTRAN) much worse.

Actually, Algol 60 lived on (and lives on, though not so much used now
outside of Scandinavia) in an improved and OOP-extended form in Simula
67 (now just Simula). Most implementations excpt that for DEC-System10
were, however, overpriced and poorly marketed, so we had to wait for
C++ (improved and OOP-extended C) for OOP to catch on.

=== 8< ===


From jurko.gospodnetic at pke.hr  Wed Mar 12 15:34:16 2014
From: jurko.gospodnetic at pke.hr (=?windows-1250?Q?Jurko_Gospodneti=E6?=)
Date: Wed, 12 Mar 2014 20:34:16 +0100
Subject: What does gc.get_objects() return?
Message-ID: <lfqcr8$249$1@ger.gmane.org>

   Hi all.

   I was wondering if someone could explain gc.get_objects() in a bit 
more detail to me.

   Does it return a list of 'all objects known to Python'? Only some of 
them? Which does it return? Which it does not?

   For example (done using CPython 3.4 interactive interpreter) here it 
does not contain an object I know exists:

> >>> a = object()
> >>> a in gc.get_objects()
> False

   but here it does:

> >>> class Foo: pass
> ...
> >>> a = Foo()
> >>> a in gc.get_objects()
> True

   It also does not seem to contain string objects. At first I thought 
that perhaps interned strings were not placed under GC control, so I 
tested this:

> >>> a = "asdkjfhk23498237$&(*$&*($ksjdhfkjsd"
> >>> b = "asdkjfhk23498237$&(*$&*($ksjdhfkjsd"
> >>> a is b
> False
> >>> a in gc.get_objects()
> False
> >>> b in gc.get_objects()
> False

   Which shows that non-interned scripts such as these are not getting 
listed in gc.get_objects() either. :-s

   Many thanks.

   Best regards,
     Jurko Gospodneti?



From emile at fenx.com  Wed Mar 12 15:38:54 2014
From: emile at fenx.com (Emile van Sebille)
Date: Wed, 12 Mar 2014 12:38:54 -0700
Subject: Save to a file, but avoid overwriting an existing file
In-Reply-To: <lfpjv9$tki$1@news1.carnet.hr>
References: <lfpjv9$tki$1@news1.carnet.hr>
Message-ID: <lfqd49$57h$1@ger.gmane.org>

On 3/12/2014 5:29 AM, zoom wrote:

> 2. Alternatively, a unique string could be generated to assure that no
> same file exists. I can see one approach to this is to include date and
> time in the file name. But this seems to me a bit clumsy, and is not
> unique, i.e. it could happen (at least in theory) that two processes
> finish in the same second.

I tend to use this method -- prepending the job name or targeting 
different directories per job precludes duplication.  Unless you're 
running the same job at the same time, in which case tempfile is the way 
to go (which I use for archiving spooled print files which can occur 
simultaneously.)

Emile







From fomcl at yahoo.com  Wed Mar 12 15:40:27 2014
From: fomcl at yahoo.com (Albert-Jan Roskam)
Date: Wed, 12 Mar 2014 12:40:27 -0700 (PDT)
Subject: locale getlocale returns None on OSX
In-Reply-To: <1394626979.46880.YahooMailBasic@web163806.mail.gq1.yahoo.com>
References: <1394626979.46880.YahooMailBasic@web163806.mail.gq1.yahoo.com>
Message-ID: <1394653227.54716.YahooMailNeo@web163806.mail.gq1.yahoo.com>



>________________________________
> From: Albert-Jan Roskam <fomcl at yahoo.com>
>To: Python <python-list at python.org> 
>Sent: Wednesday, March 12, 2014 1:22 PM
>Subject: locale getlocale returns None on OSX
> 
>
>Hi,
>
>locale.getlocale() sometimes returns (None, None) under OSX (Python 2, not sure about Python 3, but I think so). The problem is outlined here:
>http://stackoverflow.com/questions/1629699/locale-getlocale-problems-on-osx
>
>What is the cause of this? Is it limited to just Darwin systes? Does the 'horrible hack' solution on OS have any drawbacks? I like it better because it is not needed to set the LC_ALL environment variable prior to starting the Python program.
>
>Regards,
>
>Albert-Jan


Ok, here are some tests on my own system:

albertjan at debian:~$ uname -a
Linux debian 3.2.0-4-amd64 #1 SMP Debian 3.2.54-2 x86_64 GNU/Linux


Even if locale.setlocale is used first, OSX returns (None, None) when locale.getlocale() is called. Another thing that surprises me in the examples below is the output of the "python -c" example using Python 2.7. Isn't this supposed to be exactly equivalent to the code that follows?



# ======== Python 2.7 ========albertjan at debian:~$ python -c "import locale; locale.setlocale(locale.LC_ALL, ""); print(locale.getlocale())"

(None, None)?? # <---- why is this?


albertjan at debian:~$ python
Python 2.7.3 (default, Jan? 2 2013, 13:56:14) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import locale
>>> locale.setlocale(locale.LC_ALL, "")
'en_US.UTF-8'
>>> locale.getlocale()
('en_US', 'UTF-8')? # <--- OSX (sometimes?) returns (None, None) here.



# ======== Python 3.3 ========
albertjan at debian:~$ python3 -c "import locale; locale.setlocale(locale.LC_ALL, ""); print(locale.getlocale())"
('en_US', 'UTF-8')

albertjan at debian:~$ python3
Python 3.3.4 (default, Feb 17 2014, 19:23:00) 
[GCC 4.7.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import locale
>>> locale.setlocale(locale.LC_ALL, "")
'en_US.UTF-8'
>>> locale.getlocale()
('en_US', 'UTF-8')



# ======== Pypy ========
albertjan at debian:~$ pypy -c "import locale; locale.setlocale(locale.LC_ALL, ""); print locale.getlocale()"
(None, None)

albertjan at debian:~$ pypy

Python 2.7.3 (87aa9de10f9ca71da9ab4a3d53e0ba176b67d086, Mar 10 2014, 14:07:15)
[PyPy 2.2.1 with GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
And now for something completely different: ``pypy is a better kind of
foolishness - lac''
>>>> import locale
>>>> locale.setlocale(locale.LC_ALL, "")
'en_US.UTF-8'
>>>> locale.getlocale()
('en_US', 'UTF-8')


From drsalists at gmail.com  Wed Mar 12 15:53:27 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Wed, 12 Mar 2014 12:53:27 -0700
Subject: What does gc.get_objects() return?
In-Reply-To: <lfqcr8$249$1@ger.gmane.org>
References: <lfqcr8$249$1@ger.gmane.org>
Message-ID: <CAGGBd_oQVuYRpg_zO2wSSiP7x3XZ=mWPaC4EQkq6Djc0h-ui2Q@mail.gmail.com>

On Wed, Mar 12, 2014 at 12:34 PM, Jurko Gospodneti?
<jurko.gospodnetic at pke.hr> wrote:
>   Hi all.
>
>   I was wondering if someone could explain gc.get_objects() in a bit more
> detail to me.
>
>   Does it return a list of 'all objects known to Python'? Only some of them?
> Which does it return? Which it does not?
>
>   For example (done using CPython 3.4 interactive interpreter) here it does
> not contain an object I know exists:
>
>> >>> a = object()
>> >>> a in gc.get_objects()
>> False
>
>
>   but here it does:
>
>> >>> class Foo: pass
>> ...
>> >>> a = Foo()
>> >>> a in gc.get_objects()
>> True

I don't know why some objects aren't showing up in get_objects, but
here's a quick note to say it's not just 3.4:

$ ./pythons 'import gc; var="data"; print(var in gc.get_objects())'
/usr/local/cpython-2.4/bin/python
   [6600 refs]
   False
/usr/local/cpython-2.5/bin/python
   False
   [7536 refs]
/usr/local/cpython-2.6/bin/python
   False
   [15233 refs]
/usr/local/cpython-2.7/bin/python
   False
   [18526 refs]
/usr/local/cpython-3.0/bin/python
   Traceback (most recent call last):
     File "<string>", line 1, in <module>
     File "/usr/local/cpython-3.0/lib/python3.0/_weakrefset.py", line
121, in __eq__
       return self.data == set(ref(item) for item in other)
     File "/usr/local/cpython-3.0/lib/python3.0/_weakrefset.py", line
121, in <genexpr>
       return self.data == set(ref(item) for item in other)
   TypeError: cannot create weak reference to 'str' object
   [34510 refs]
/usr/local/cpython-3.1/bin/python
   False
   [37270 refs]
/usr/local/cpython-3.2/bin/python
   False
   [37700 refs]
/usr/local/cpython-3.3/bin/python
   False
   [42662 refs]
/usr/local/cpython-3.4/bin/python False
/usr/local/pypy-2.2/bin/pypy True
/usr/local/jython-2.7b1/bin/jython
   Traceback (most recent call last):
     File "<string>", line 1, in <module>
   NotImplementedError: not applicable to Java GC

Interesting that it is present in Pypy.


From python at mrabarnett.plus.com  Wed Mar 12 16:02:07 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 12 Mar 2014 20:02:07 +0000
Subject: What does gc.get_objects() return?
In-Reply-To: <lfqcr8$249$1@ger.gmane.org>
References: <lfqcr8$249$1@ger.gmane.org>
Message-ID: <5320BD3F.5030509@mrabarnett.plus.com>

On 2014-03-12 19:34, Jurko Gospodneti? wrote:
>     Hi all.
>
>     I was wondering if someone could explain gc.get_objects() in a bit
> more detail to me.
>
>     Does it return a list of 'all objects known to Python'? Only some of
> them? Which does it return? Which it does not?
>
[snip]

gc.is_tracked(...) might be relevant to your question.



From nad at acm.org  Wed Mar 12 16:43:44 2014
From: nad at acm.org (Ned Deily)
Date: Wed, 12 Mar 2014 13:43:44 -0700
Subject: locale getlocale returns None on OSX
References: <1394626979.46880.YahooMailBasic@web163806.mail.gq1.yahoo.com>
Message-ID: <nad-43391B.13434412032014@news.gmane.org>

In article 
<1394626979.46880.YahooMailBasic at web163806.mail.gq1.yahoo.com>,
 Albert-Jan Roskam <fomcl at yahoo.com> wrote:
> locale.getlocale() sometimes returns (None, None) under OSX (Python 2, not 
> sure about Python 3, but I think so). The problem is outlined here:
> http://stackoverflow.com/questions/1629699/locale-getlocale-problems-on-osx

Python's locale uses the plaform's locale implementation and POSIX 
locale is an old and somewhat weird animal.  Make sure you thoroughly 
read the description of the locale module, in particular, the caveats 
section:

http://docs.python.org/2/library/locale.html#background-details-hints-tip
s-and-caveats

The first gotcha is that you need to explicitly call 
locale.setlocale("LC_ALL,"") to get the preferred locale environment, as 
either specified by the user, by LANG or other LC_* environment 
variables, or the platform defaults.  In general, OS X does not provide 
a default for your process.  However, various environments do.  The OS X 
Terminal.app has profile settings (Preferences -> Settings -> (Profile 
name) -> Advanced) to specific a character encoding and a checkbox to 
"Set locale environment variables on startup".  With that set properly, 
programs run under Terminal.app will see LANG set.  The user can also 
set an explicit LANG value in a shell profile, like .profile or .bashrc, 
but those only apply when a shell is being used.  Depending on which 
profile it is set in, that might not work under all conditions, like 
under "sudo" or in an "ssh" session.  Setting an env variable in a shell 
profile would also not apply to an double-clickable app bundle since no 
shell is involved in launching it; it is possible to set environment 
variables in the app's Info.plist, though.
 
> What is the cause of this? Is it limited to just Darwin systes? Does the 
> 'horrible hack' solution on OS have any drawbacks? I like it better because 
> it is not needed to set the LC_ALL environment variable prior to starting the 
> Python program.

As the caveats section points out, setting locale env vars may have 
unwanted side effects on other parts of the process it is running in or 
creates.  So, if you are using it in a standalone program, it may be OK.  
If you are using it a module intended to be used by other programs, you 
probably shouldn't be changing something that could break other parts of 
the calling program.

-- 
 Ned Deily,
 nad at acm.org



From jurko.gospodnetic at pke.hr  Wed Mar 12 17:28:13 2014
From: jurko.gospodnetic at pke.hr (=?UTF-8?B?SnVya28gR29zcG9kbmV0acSH?=)
Date: Wed, 12 Mar 2014 22:28:13 +0100
Subject: What does gc.get_objects() return?
In-Reply-To: <5320BD3F.5030509@mrabarnett.plus.com>
References: <lfqcr8$249$1@ger.gmane.org> <5320BD3F.5030509@mrabarnett.plus.com>
Message-ID: <lfqjgu$kug$1@ger.gmane.org>

   Hi.

On 12.3.2014. 21:02, MRAB wrote:
>>     I was wondering if someone could explain gc.get_objects() in a bit
>> more detail to me.
>>
>>     Does it return a list of 'all objects known to Python'? Only some of
>> them? Which does it return? Which it does not?
>>
>
> gc.is_tracked(...) might be relevant to your question.

   Thanks! The documentation for gc.is_tracked() straightened me out. :-)

   So gc.collect() returns a list of all the objects GC is in charge of, 
and which instances are and are not tracked by the GC is, I guess, an 
interpreter implementation detail.

   For CPython 3.4 I guess strings and other atomic types such as ints 
are not, as well as raw object() instances. Custom class instances on 
the other hand seem to be under GC control.

   Thanks again.

   Best regards,
     Jurko Gospodneti?




From skip at pobox.com  Wed Mar 12 17:44:07 2014
From: skip at pobox.com (Skip Montanaro)
Date: Wed, 12 Mar 2014 16:44:07 -0500
Subject: DB API question - where is a stored procedure's return value?
Message-ID: <CANc-5Uz98mTCjUuk_yOHqWeZRwp6JnTCagTQ=bzobhtWAceKxg@mail.gmail.com>

I've stumbled on a problem with the python-sybase module. If I have a
stored procedure like this:

create stored procedure test_proc
as
    return 1

and call it from Python like this:

curs.callproc("test_proc", {})

it's not clear to me where the return status is stored. Currently, the
python-sybase module provides (I believe) the ability to set output
parameters (those specified as such in the argument dictionary), and
you can iterate over all the result sets the stored procedure
produces.

Looking at the Python database API (PEP 249), I saw no mention of the
return status:

.callproc( procname [, parameters ] )

(This method is optional since not all databases provide stored procedures. [3])

Call a stored database procedure with the given name. The sequence of
parameters must contain one entry for each argument that the procedure
expects. The result of the call is returned as modified copy of the
input sequence. Input parameters are left untouched, output and
input/output parameters replaced with possibly new values.

The procedure may also provide a result set as output. This must then
be made available through the standard.fetch*() methods.

I see no mention of how to handle the return value. The "modified copy
of the input sequence" is just that. In the case of the python-sybase
module, any parameter values in the input dictionary  of type
DataBufType are rewritten with values from the first row of the first
result set. The Cursor class also defines a _status_result() method,
which sounds promising. I haven't had a chance to try it out yet. My
concern is more that the Python database API doesn't mention stored
procedure return values at all.

What do other database adaptors do about stored procedure return
values? Does PEP 249 need revision?

Skip


From rosuav at gmail.com  Wed Mar 12 17:44:56 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 13 Mar 2014 08:44:56 +1100
Subject: What does gc.get_objects() return?
In-Reply-To: <lfqjgu$kug$1@ger.gmane.org>
References: <lfqcr8$249$1@ger.gmane.org> <5320BD3F.5030509@mrabarnett.plus.com>
 <lfqjgu$kug$1@ger.gmane.org>
Message-ID: <CAPTjJmqdKZ6qDQ+PZAdxVF-hKN=txKh35ga_C451C2z_hpZZAA@mail.gmail.com>

On Thu, Mar 13, 2014 at 8:28 AM, Jurko Gospodneti?
<jurko.gospodnetic at pke.hr> wrote:
>   So gc.collect() returns a list of all the objects GC is in charge of, and
> which instances are and are not tracked by the GC is, I guess, an
> interpreter implementation detail.

I assume you don't mean collect() there, as that returns the amount of
garbage that it just collected :)

It's not strictly an implementation detail, beyond that there are
certain optimizations. For instance...

>   For CPython 3.4 I guess strings and other atomic types such as ints are
> not, as well as raw object() instances. Custom class instances on the other
> hand seem to be under GC control.

... strings and ints should never be listed, and custom objects should
always be listed, but I'd say the non-tracking of object() would be an
implementation-specific optimization. Definitely the non-tracking of a
dict of nothing but atomic keys and values would be that.

The concept is that the GC tracks (in that sense; everything in
CPython is refcounted, but that's not what these functions look at)
anything that could be a part of a reference cycle. That's all it
concerns itself with, so something that can't have references to
arbitrary objects can't possibly be worth tracking. Interestingly, a
tuple of integers is tracked:

>>> a=1,2,3
>>> gc.is_tracked(a)
True

So not all optimizations are done that could be done.

ChrisA


From i.thrinaxodon at bitch.invalid  Wed Mar 12 18:08:41 2014
From: i.thrinaxodon at bitch.invalid (I THRINAXODON)
Date: Wed, 12 Mar 2014 18:08:41 -0400
Subject: TALK.ORIGINS CENSORS THE TRUTH
Message-ID: <lfqlso$e38$2@speranza.aioe.org>

EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/6f501c469c7af24f# 


https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/3aad75c16afb0b82# 


====================================

http://thrinaxodon.wordpress.com/

===================================

THRINAXODON ONLY HAD THIS TO SAY:

"I..I...I...Can't believe it. This completely disproved Darwinian
orthodoxy."

===================================

THE BASTARDS AT THE SMITHSONIAN, AND THE LEAKEY FOUNDATION ARE ERODING
WITH FEAR.

===========================
THESE ASSHOLES ARE GOING TO DIE:
THOMAS AQUINAS;
ALDOUS HUXLEY;
BOB CASANVOVA;
SkyEyes;
DAVID IAIN GRIEG;
MARK ISAAK;
JOHN HARSHAM;
RICHARD NORMAN;
DR. DOOLITTLE;
CHARLES DARWIN;
MARK HORTON;
ERIK SIMPSON;
HYPATIAB7;
PAUL J. GANS;
JILLERY;
WIKI TRIK;
THRINAXODON;
PETER NYIKOS;
RON OKIMOTO;
JOHN S. WILKINS
===========================

THRINAXODON WAS SCOURING ANOTHER DEVONIAN FOSSIL BED, AND FOUND A
HUMAN SKULL, AND A HUMAN FEMUR. HE ANALYSED THE FINDS, AND SAW THAT
THEY WERE NOT NORMAL ROCKS. THESE WERE FOSSILIZED BONES. THEY EVEN HAD
TOOTH MARKS ON THEM. SO, THRINAXODON BROUGHT THEM TO THE LEAKEY
FOUNDATION, THEY UTTERLY DISMISSED IT, AND SAID, "We want to keep
people thinking that humans evolved 2 Ma." THRINAXODON BROUGHT HIS
SWORD, AND SAID, "SCIENCE CORRECTS ITSELF." RICHARD LEAKEY SAID, "That
is a myth, for people to believe in science." THRINAXODON PLANS TO
BRING DOOM TO SCIENCE, ITSELF.

============================

THRINAXODON IS NOW ON REDDIT

-- 
---Thrinaxodon



From ian.g.kelly at gmail.com  Wed Mar 12 18:35:13 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 12 Mar 2014 16:35:13 -0600
Subject: What does gc.get_objects() return?
In-Reply-To: <CAPTjJmqdKZ6qDQ+PZAdxVF-hKN=txKh35ga_C451C2z_hpZZAA@mail.gmail.com>
References: <lfqcr8$249$1@ger.gmane.org> <5320BD3F.5030509@mrabarnett.plus.com>
 <lfqjgu$kug$1@ger.gmane.org>
 <CAPTjJmqdKZ6qDQ+PZAdxVF-hKN=txKh35ga_C451C2z_hpZZAA@mail.gmail.com>
Message-ID: <CALwzidn4o-z=wvGS89-WvL=DivBm0T3GSbTV0qcUJFE5zmo2XA@mail.gmail.com>

On Wed, Mar 12, 2014 at 3:44 PM, Chris Angelico <rosuav at gmail.com> wrote:
> The concept is that the GC tracks (in that sense; everything in
> CPython is refcounted, but that's not what these functions look at)
> anything that could be a part of a reference cycle. That's all it
> concerns itself with, so something that can't have references to
> arbitrary objects can't possibly be worth tracking. Interestingly, a
> tuple of integers is tracked:
>
>>>> a=1,2,3
>>>> gc.is_tracked(a)
> True
>
> So not all optimizations are done that could be done.

Or is it?

>>> a = 1,2,3
>>> gc.is_tracked(a)
True
>>> gc.collect()
0
>>> gc.is_tracked(a)
False


From ian.g.kelly at gmail.com  Wed Mar 12 18:40:00 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 12 Mar 2014 16:40:00 -0600
Subject: What does gc.get_objects() return?
In-Reply-To: <CALwzidn4o-z=wvGS89-WvL=DivBm0T3GSbTV0qcUJFE5zmo2XA@mail.gmail.com>
References: <lfqcr8$249$1@ger.gmane.org> <5320BD3F.5030509@mrabarnett.plus.com>
 <lfqjgu$kug$1@ger.gmane.org>
 <CAPTjJmqdKZ6qDQ+PZAdxVF-hKN=txKh35ga_C451C2z_hpZZAA@mail.gmail.com>
 <CALwzidn4o-z=wvGS89-WvL=DivBm0T3GSbTV0qcUJFE5zmo2XA@mail.gmail.com>
Message-ID: <CALwzidnbry5nJg0aLEr7yCcDmykr2QSeEcJ8NtVjRvj_4ce5rQ@mail.gmail.com>

On Wed, Mar 12, 2014 at 4:35 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> So not all optimizations are done that could be done.
>
> Or is it?
>
>>>> a = 1,2,3
>>>> gc.is_tracked(a)
> True
>>>> gc.collect()
> 0
>>>> gc.is_tracked(a)
> False

I guess the reason for this is that when PyTuple_New is called, it
knows how many elements it will contain but doesn't know yet what they
are, so it defers the issue by just going ahead and adding itself to
the GC


From cs at zip.com.au  Wed Mar 12 18:19:25 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Thu, 13 Mar 2014 09:19:25 +1100
Subject: Save to a file, but avoid overwriting an existing file
In-Reply-To: <lfpjv9$tki$1@news1.carnet.hr>
References: <lfpjv9$tki$1@news1.carnet.hr>
Message-ID: <20140312221925.GA67514@cskk.homeip.net>

On 12Mar2014 13:29, zoom <zoom at yahoo.com> wrote:
> I would like to assure that when writing to a file I do not
> overwrite an existing file, but I'm unsure which is the best way to
> approach to this problem. As I can see, there are at least two
> possibilities:
> 
> 1. I could use fd = os.open("x", os.O_WRONLY | os.O_CREAT | os.O_EXCL)
> which will fail - if the file exists. However, I would prefer if the
> program would try to save under different name in this case, instead
> of discarding all the calculation done until now - but I' not too
> well with catching exceptions.

Others have menthions tempfile, though of course you have the same collision
issue when you come to rename the temp file if you are keeping it.

I would run with option 1 for your task.

Just iterate until os.open succeeds.

However, you need to distinuish _why_ an open fails. For example,
if you were trying to make files in a directory to which you do not
have write permission, or just a directory that did not exist,
os.open would fail not matter what name you used, so your loop would
run forever.

Therefore you need to continue _only_ if you get EEXIST. Otherwise abort.

So you'd have some code like this (totally untested):

  # at top of script
  import errno

  # where you make the file
  def open_new(primary_name):
    try:
      fd = os.open(primary_name, os.O_WRONLY | os.O_CREAT | os.O_EXCL)
    except OSError as e:
      if e.errno != errno.EEXIST:
        raise
    else:
      return primary_name, fd
    n = 1
    while True:
      secondary_name = "%s.%d" % (primary_name, n)
      try:
        fd = os.open(secondary_name, os.O_WRONLY | os.O_CREAT | os.O_EXCL)
      except OSError as e:
        if e.errno != errno.EEXIST:
          raise
      else:
        return secondary_name, fd
      n += 1

  # where you need the file
  path, fd = open_new("x")

That gets you a function your can reuse which returns the file's
name and the file descriptor.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

Reason #173 to fear technology:

    o       o       o       o       o       o      <o      <o>
   ^|\     ^|^     v|^     v|v     |/v     |X|      \|      |
    /\      >\     /<       >\     /<       >\     /<       >\

    o>      o       o       o       o       o       o       o
    \       x      </      <|>     </>     <\>     <)>      |\
   /<       >\     /<       >\     /<       >\      >>      L

             Mr. email does the Macarena.


From ian.g.kelly at gmail.com  Wed Mar 12 19:00:12 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 12 Mar 2014 17:00:12 -0600
Subject: DB API question - where is a stored procedure's return value?
In-Reply-To: <CANc-5Uz98mTCjUuk_yOHqWeZRwp6JnTCagTQ=bzobhtWAceKxg@mail.gmail.com>
References: <CANc-5Uz98mTCjUuk_yOHqWeZRwp6JnTCagTQ=bzobhtWAceKxg@mail.gmail.com>
Message-ID: <CALwzidm0GJ37JTjUUGPPgEXnZoh0ck08B7i2H4SZXXD1VyDcbA@mail.gmail.com>

On Wed, Mar 12, 2014 at 3:44 PM, Skip Montanaro <skip at pobox.com> wrote:
> What do other database adaptors do about stored procedure return
> values? Does PEP 249 need revision?

I can't speak generally, but in cx_Oracle you either execute a query like this:

    result = cursor.var(cx_Oracle.NUMBER)
    cursor.execute(":1 := test_proc()", [result])
    print(result.getvalue())

or you use the non-standard callfunc method:

    print(cursor.callfunc("test_proc", cx_Oracle.NUMBER))

As a general solution, one might wrap a stored procedure that returns
a value into a stored procedure that has an output parameter and call
it with callproc.  Some implementations might include a return value
in the parameter list anyway.


From breamoreboy at yahoo.co.uk  Wed Mar 12 19:04:13 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 12 Mar 2014 23:04:13 +0000
Subject: Save to a file, but avoid overwriting an existing file
In-Reply-To: <20140312221925.GA67514@cskk.homeip.net>
References: <lfpjv9$tki$1@news1.carnet.hr>
 <20140312221925.GA67514@cskk.homeip.net>
Message-ID: <lfqp5d$kr1$1@ger.gmane.org>

On 12/03/2014 22:19, Cameron Simpson wrote:
> On 12Mar2014 13:29, zoom <zoom at yahoo.com> wrote:
>> I would like to assure that when writing to a file I do not
>> overwrite an existing file, but I'm unsure which is the best way to
>> approach to this problem. As I can see, there are at least two
>> possibilities:
>>
>> 1. I could use fd = os.open("x", os.O_WRONLY | os.O_CREAT | os.O_EXCL)
>> which will fail - if the file exists. However, I would prefer if the
>> program would try to save under different name in this case, instead
>> of discarding all the calculation done until now - but I' not too
>> well with catching exceptions.
>
> Others have menthions tempfile, though of course you have the same collision
> issue when you come to rename the temp file if you are keeping it.
>
> I would run with option 1 for your task.
>
> Just iterate until os.open succeeds.
>
> However, you need to distinuish _why_ an open fails. For example,
> if you were trying to make files in a directory to which you do not
> have write permission, or just a directory that did not exist,
> os.open would fail not matter what name you used, so your loop would
> run forever.
>
> Therefore you need to continue _only_ if you get EEXIST. Otherwise abort.
>
> So you'd have some code like this (totally untested):
>
>    # at top of script
>    import errno
>
>    # where you make the file
>    def open_new(primary_name):
>      try:
>        fd = os.open(primary_name, os.O_WRONLY | os.O_CREAT | os.O_EXCL)
>      except OSError as e:
>        if e.errno != errno.EEXIST:
>          raise
>      else:
>        return primary_name, fd
>      n = 1
>      while True:
>        secondary_name = "%s.%d" % (primary_name, n)
>        try:
>          fd = os.open(secondary_name, os.O_WRONLY | os.O_CREAT | os.O_EXCL)
>        except OSError as e:
>          if e.errno != errno.EEXIST:
>            raise
>        else:
>          return secondary_name, fd
>        n += 1
>
>    # where you need the file
>    path, fd = open_new("x")
>
> That gets you a function your can reuse which returns the file's
> name and the file descriptor.
>
> Cheers,
>

I haven't looked but would things be easier if the new exception 
hierarchy were used 
http://docs.python.org/3.3/whatsnew/3.3.html#pep-3151-reworking-the-os-and-io-exception-hierarchy 
?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ian.g.kelly at gmail.com  Wed Mar 12 19:06:50 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 12 Mar 2014 17:06:50 -0600
Subject: DB API question - where is a stored procedure's return value?
In-Reply-To: <CALwzidm0GJ37JTjUUGPPgEXnZoh0ck08B7i2H4SZXXD1VyDcbA@mail.gmail.com>
References: <CANc-5Uz98mTCjUuk_yOHqWeZRwp6JnTCagTQ=bzobhtWAceKxg@mail.gmail.com>
 <CALwzidm0GJ37JTjUUGPPgEXnZoh0ck08B7i2H4SZXXD1VyDcbA@mail.gmail.com>
Message-ID: <CALwzidmhG_=tLUUhqx7DJ92=Vr5f6niuY_Wzg8xWQvjo6GJ9tQ@mail.gmail.com>

On Wed, Mar 12, 2014 at 5:00 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>     result = cursor.var(cx_Oracle.NUMBER)
>     cursor.execute(":1 := test_proc()", [result])
>     print(result.getvalue())

Sorry, that should properly be:

    result = cursor.var(cx_Oracle.NUMBER)
    cursor.execute("BEGIN :1 := test_proc(); END;", [result])
    print(result.getvalue())


From steve+comp.lang.python at pearwood.info  Wed Mar 12 19:07:53 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 12 Mar 2014 23:07:53 GMT
Subject: Deep vs. shallow copy?
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
Message-ID: <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Wed, 12 Mar 2014 15:29:59 +0000, Alex van der Spek wrote:

> Having been taught programming in Algol60 Python still defeats me at
> times! Particularly since Algol60 wasn't very long lived and what came
> thereafter (FORTRAN) much worse.

Fortran came first. Fortran was the first high-level language which 
allowed the programmer to write things that looked rather like the sorts 
of mathematical expressions they were used to.

There were a few higher-level assembly languages that came before 
Fortran, such as SpeedCoding, Fortran's predecessor, but Fortran was the 
first truly high-level programming language, and even in 1957 it came 
with an optimizing compiler.

I'm not really familiar with Algol, but I do know Pascal, and you should 
think of the append method to be like a Pascal procedure. Because Python 
doesn't have true procedures, it follows the convention that returning 
the special object None signals the intention to return nothing at all. 
Hence your example below:


>>>> c = a.append(b)
>>>> print c
> None





-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Wed Mar 12 19:14:07 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 13 Mar 2014 10:14:07 +1100
Subject: What does gc.get_objects() return?
In-Reply-To: <CALwzidn4o-z=wvGS89-WvL=DivBm0T3GSbTV0qcUJFE5zmo2XA@mail.gmail.com>
References: <lfqcr8$249$1@ger.gmane.org> <5320BD3F.5030509@mrabarnett.plus.com>
 <lfqjgu$kug$1@ger.gmane.org>
 <CAPTjJmqdKZ6qDQ+PZAdxVF-hKN=txKh35ga_C451C2z_hpZZAA@mail.gmail.com>
 <CALwzidn4o-z=wvGS89-WvL=DivBm0T3GSbTV0qcUJFE5zmo2XA@mail.gmail.com>
Message-ID: <CAPTjJmrD7vsWg1kZQ2x0kZ0uPiZVZLbo9Gt=BFHaRua5_ut77A@mail.gmail.com>

On Thu, Mar 13, 2014 at 9:35 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> Or is it?
>
>>>> a = 1,2,3
>>>> gc.is_tracked(a)
> True
>>>> gc.collect()
> 0
>>>> gc.is_tracked(a)
> False

Huh, *that* is interesting!

ChrisA


From petite.abeille at gmail.com  Wed Mar 12 19:11:09 2014
From: petite.abeille at gmail.com (Petite Abeille)
Date: Thu, 13 Mar 2014 00:11:09 +0100
Subject: DB API question - where is a stored procedure's return value?
In-Reply-To: <CALwzidm0GJ37JTjUUGPPgEXnZoh0ck08B7i2H4SZXXD1VyDcbA@mail.gmail.com>
References: <CANc-5Uz98mTCjUuk_yOHqWeZRwp6JnTCagTQ=bzobhtWAceKxg@mail.gmail.com>
 <CALwzidm0GJ37JTjUUGPPgEXnZoh0ck08B7i2H4SZXXD1VyDcbA@mail.gmail.com>
Message-ID: <C4856181-AC31-4098-A3C3-638728DECF41@gmail.com>


On Mar 13, 2014, at 12:00 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:

> As a general solution, one might wrap a stored procedure that returns
> a value into a stored procedure that has an output parameter and call
> it with callproc.  Some implementations might include a return value
> in the parameter list anyway.

Alternatively? if it?s really a function? wrap it in a select statement? such as:

select foo() as value from dual



From steve+comp.lang.python at pearwood.info  Wed Mar 12 19:14:51 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 12 Mar 2014 23:14:51 GMT
Subject: unittest weirdness
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <lfo1qj$3m3$1@reader1.panix.com> <lfokoh$3q3$1@ger.gmane.org>
 <mailman.8082.1394620172.18130.python-list@python.org>
 <roy-66F336.09444712032014@news.panix.com>
 <mailman.8095.1394640002.18130.python-list@python.org>
Message-ID: <5320ea6b$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Wed, 12 Mar 2014 08:32:29 -0700, Ethan Furman wrote:

> There must
> be waaaaaaay too much stuff being kept alive by the stack traces of the
> failed tests.


I believe that unittest does keep stack traces alive until the process 
ends. I thought that there was a recent bug report for it, but the only 
one I can find was apparently fixed more than a decade ago:

http://bugs.python.org/issue451309





-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Wed Mar 12 19:20:46 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 12 Mar 2014 23:20:46 GMT
Subject: Tuples and immutability
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
 <bo7jo9Fsaf1U1@mid.individual.net>
 <mailman.8040.1394534428.18130.python-list@python.org>
 <531f3dfb$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8066.1394579251.18130.python-list@python.org>
Message-ID: <5320ebce$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 11 Mar 2014 17:06:43 -0600, Ian Kelly wrote:

> On Tue, Mar 11, 2014 at 10:46 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>>> There are a number of possible solutions.  One possibility would be to
>>> copy the Circle as an Ellipse and return the new object instead of
>>> mutating it. Then you have the situation where, given a mutable object
>>> x that satisfies isinstance(x, Ellipse), the stretch method *may* be
>>> able to update the object in-place, or it *may* not.
>>
>> That is a really lousy design. Of course we are free to create classes
>> with ugly, inconsistent, stupid or unworkable APIs if we like. Python
>> won't stop us:
> 
> That's true but irrelevant to my point, which was to counter the
> assertion that mutable types can always be assumed to be able to perform
> operations in-place.

"Always"? Not so fast.

This is Python. We have freedom to abuse nearly everything, and if you 
want to shoot yourself in the foot, you can. With the exception of a 
handful of things which cannot be overridden (e.g. None, numeric 
literals, syntax) you cannot strictly assume anything about anything. 
Python does not enforce that iterators raise StopIteration when empty, or 
that indexing beyond the boundaries of a sequence raises IndexError, or 
that __setitem__ of a mapping sets the key and value, or that __len__ 
returns a length.

Augmented assignment is no different. The docs describe the intention of 
the designers and the behaviour of the classes that they control, so with 
standard built-in classes like int, str, list, tuple etc. you can safely 
assume that mutable types will perform the operation in place and 
immutable types won't, but with arbitrary types from some arbitrarily 
eccentric or twisted programmer, who knows what it will do?


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Wed Mar 12 19:38:56 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 12 Mar 2014 23:38:56 GMT
Subject: unittest weirdness
References: <mailman.8062.1394573210.18130.python-list@python.org>
Message-ID: <5320f00f$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 11 Mar 2014 13:58:17 -0700, Ethan Furman wrote:

> class Test_wfbrp_20140225(TestCase):
> 
>      @classmethod
>      def setUpClass(cls):
>          cls.pp = wfbrp.PaymentProcessor(
>              '.../lockbox_file',
>              '.../aging_file',
>              [
>                  Path('month_end_1'),
>                  Path('month_end_2'),
>                  Path('month_end_3'),
>                  ],
>              )

This has nothing to do with your actual problem, which appears to be the 
Linux(?) OOM killer reaping your applications, just some general 
observations on your test.


>      def test_xxx_1(self):

Having trouble thinking up descriptive names for the test? That's a sign 
that the test might be doing too much. Each test should check one self-
contained thing. That may or may not be a single call to a unittest 
assert* method, but it should be something you can describe in a few 
words:

"it's a regression test for bug 23"
"test that the database isn't on fire"
"invoices should have a valid debtor"
"the foo report ought to report all the foos"
"...and nothing but the foos."

This hints -- its just a hint, mind you, since I lack all specific 
knowledge of your application -- that the following "affirm" tests should 
be pulled out into separate tests.

>          p = self.pp.lockbox_payments[0]
>          # affirm we have what we're expecting 
>          self.assertEqual(
>                  (p.payer, p.ck_num, p.credit),
>                  ('a customer', '010101', 10000),
>                  )
>          self.assertEqual(p.invoices.keys(), ['XXXXXXXXXXX'])
>          self.assertEqual(p.invoices.values()[0].amount, 10000)

which would then leave this to be the Actual Thing Being Tested for this 
test, which then becomes test_no_missing_invoices rather than test_xxx_1.

>          # now make sure we get back what we're expecting 
>          np, b = self.pp._match_invoices(p)
>          missing = []
>          for inv_num in ('123456', '789012', '345678'):
>              if inv_num not in b:
>                  missing.append(inv_num)
>          if missing:
>              raise ValueError('invoices %r missing from batch' %
>              missing)

Raising an exception directly inside the test function should only occur 
if the test function is buggy. As Terry has already suggested, this 
probably communicates your intention much better:

    self.assertEqual(missing, [])



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Wed Mar 12 19:47:47 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 12 Mar 2014 23:47:47 GMT
Subject: unittest weirdness
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <lfo1qj$3m3$1@reader1.panix.com> <lfokoh$3q3$1@ger.gmane.org>
 <mailman.8082.1394620172.18130.python-list@python.org>
 <roy-66F336.09444712032014@news.panix.com>
 <mailman.8095.1394640002.18130.python-list@python.org>
Message-ID: <5320f223$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Wed, 12 Mar 2014 08:32:29 -0700, Ethan Furman wrote:

>> Some systems have an oom (Out Of Memory) process killer, which nukes
>> (semi-random) process when the system exhausts memory.  Is it possible
>> this is happening?  If so, you should see some log message in one of
>> your system logs.
> 
> That would explain why my editor windows were being killed.


Try opening a second console tab and running top in it. It will show the 
amount of memory being used. Then run the tests in the first, jump back 
to top, and watch to see if memory use goes through the roof:

top -Mm -d 0.5

will sort by memory use, display memory in more sensible human-readable 
units instead of bytes, and update the display every 0.5 second. You can 
then hit the "i" key to toggle display of idle processes and only show 
those that are actually doing something (which presumably will include 
Python running the tests).

This at least will allow you to see whether or not memory is the concern.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ben+python at benfinney.id.au  Wed Mar 12 20:22:55 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 13 Mar 2014 11:22:55 +1100
Subject: Save to a file, but avoid overwriting an existing file
References: <lfpjv9$tki$1@news1.carnet.hr>
 <20140312221925.GA67514@cskk.homeip.net>
Message-ID: <85zjkvrlpc.fsf@benfinney.id.au>

Cameron Simpson <cs at zip.com.au> writes:

> Therefore you need to continue _only_ if you get EEXIST. Otherwise
> abort.

If you target Python 3.3 or later, you can catch ?FileExistsError?
<URL:http://docs.python.org/3/library/exceptions.html#FileExistsError>
which is far simpler than messing around with ?errno? values.

-- 
 \     ?I know you believe you understood what you think I said, but I |
  `\         am not sure you realize that what you heard is not what I |
_o__)                                     meant.? ?Robert J. McCloskey |
Ben Finney



From ethan at stoneleaf.us  Wed Mar 12 20:31:14 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Wed, 12 Mar 2014 17:31:14 -0700
Subject: unittest weirdness
In-Reply-To: <5320f223$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <lfo1qj$3m3$1@reader1.panix.com> <lfokoh$3q3$1@ger.gmane.org>
 <mailman.8082.1394620172.18130.python-list@python.org>
 <roy-66F336.09444712032014@news.panix.com>
 <mailman.8095.1394640002.18130.python-list@python.org>
 <5320f223$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5320FC52.7090902@stoneleaf.us>

On 03/12/2014 04:47 PM, Steven D'Aprano wrote:
>
> top -Mm -d 0.5

Cool, thanks!

--
~Ethan~


From ethan at stoneleaf.us  Wed Mar 12 20:36:03 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Wed, 12 Mar 2014 17:36:03 -0700
Subject: unittest weirdness
In-Reply-To: <5320f00f$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <5320f00f$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5320FD73.7080603@stoneleaf.us>

On 03/12/2014 04:38 PM, Steven D'Aprano wrote:
>
> [snip lots of good advice for unit testing]

I was just removing the Personally Identifiable Information.  Each test is pulling a payment from a batch of payments, 
so the first couple asserts are simply making sure I have the payment I think I have, then I run the routine that is 
supposed to match that payment with a bunch of invoices, and then I test to make sure I got back the invoices that I 
have manually verified are the correct ones to be returned.

There are many different tests because there are many different paths through the code, depending on exactly which 
combination of insanities the bank, the customer, and the company choose to inflict at that moment.  ;)

--
~Ethan~


From ian.g.kelly at gmail.com  Wed Mar 12 21:35:29 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 12 Mar 2014 19:35:29 -0600
Subject: Tuples and immutability
In-Reply-To: <5320ebce$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
 <bo7jo9Fsaf1U1@mid.individual.net>
 <mailman.8040.1394534428.18130.python-list@python.org>
 <531f3dfb$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8066.1394579251.18130.python-list@python.org>
 <5320ebce$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALwzid=_y=DPujKZAqPvRqDSFGB7=zvbW=Egx+Y5F+gQ8UpCpQ@mail.gmail.com>

On Wed, Mar 12, 2014 at 5:20 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Tue, 11 Mar 2014 17:06:43 -0600, Ian Kelly wrote:
>
>> That's true but irrelevant to my point, which was to counter the
>> assertion that mutable types can always be assumed to be able to perform
>> operations in-place.
>
> "Always"? Not so fast.
>
> This is Python. We have freedom to abuse nearly everything, and if you
> want to shoot yourself in the foot, you can. With the exception of a
> handful of things which cannot be overridden (e.g. None, numeric
> literals, syntax) you cannot strictly assume anything about anything.
> Python does not enforce that iterators raise StopIteration when empty, or
> that indexing beyond the boundaries of a sequence raises IndexError, or
> that __setitem__ of a mapping sets the key and value, or that __len__
> returns a length.

Thank you; you've stated my point more succinctly than I did.

> Augmented assignment is no different. The docs describe the intention of
> the designers and the behaviour of the classes that they control, so with
> standard built-in classes like int, str, list, tuple etc. you can safely
> assume that mutable types will perform the operation in place and
> immutable types won't, but with arbitrary types from some arbitrarily
> eccentric or twisted programmer, who knows what it will do?

This got me curious about how consistent the standard library is about
this exactly, so I did some grepping.  In the standard library there
are 5 mutable types that support concatenation that I was able to
find: list, deque, array, bytearray, and Counter.  There are none that
support addition, which I find interesting in that the language
provides hooks for in-place addition but never uses them itself.

All of the classes above appear to follow the rule that if you can
concatenate an operand, you can in-place concatenate the same operand.
 The converse however does not hold:  list.__iadd__ and
Counter.__iadd__ are both more permissive in what types they will
accept than their __add__ counterparts, and especially interesting to
me is that deque implements __iadd__ but does not implement __add__ at
all.  This last in particular seems to support the assertion that +=
should be viewed more as a shorthand for an in-place operation, less
as an equivalent for x = x + y.

>>> l = [1,2,3]
>>> l + (4,5,6)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can only concatenate list (not "tuple") to list
>>> l += (4,5,6)
>>> l
[1, 2, 3, 4, 5, 6]

>>> c = collections.Counter('mississippi')
>>> c + collections.Counter('alabama')
Counter({'s': 4, 'a': 4, 'i': 4, 'p': 2, 'm': 2, 'b': 1, 'l': 1})
>>> c + dict({'a': 4, 'l': 1, 'b': 1, 'm': 1})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'Counter' and 'dict'
>>> c += dict({'a': 4, 'l': 1, 'b': 1, 'm': 1})
>>> c
Counter({'s': 4, 'a': 4, 'i': 4, 'p': 2, 'm': 2, 'b': 1, 'l': 1})

>>> d = collections.deque([1,2,3])
>>> d += [4,5,6]
>>> d
deque([1, 2, 3, 4, 5, 6])
>>> d + [7,8,9]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'collections.deque' and 'list'
>>> d.__add__
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'collections.deque' object has no attribute '__add__'


From tjreedy at udel.edu  Wed Mar 12 22:09:24 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 12 Mar 2014 22:09:24 -0400
Subject: Tuples and immutability
In-Reply-To: <CALwzid=_y=DPujKZAqPvRqDSFGB7=zvbW=Egx+Y5F+gQ8UpCpQ@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <bo1rjpFll5mU1@mid.individual.net>
 <mailman.7944.1394332838.18130.python-list@python.org>
 <bo46qcF6dofU1@mid.individual.net>
 <mailman.7972.1394408612.18130.python-list@python.org>
 <bo7jo9Fsaf1U1@mid.individual.net>
 <mailman.8040.1394534428.18130.python-list@python.org>
 <531f3dfb$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8066.1394579251.18130.python-list@python.org>
 <5320ebce$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CALwzid=_y=DPujKZAqPvRqDSFGB7=zvbW=Egx+Y5F+gQ8UpCpQ@mail.gmail.com>
Message-ID: <lfr40r$5f3$1@ger.gmane.org>

On 3/12/2014 9:35 PM, Ian Kelly wrote:
> On Wed, Mar 12, 2014 at 5:20 PM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> On Tue, 11 Mar 2014 17:06:43 -0600, Ian Kelly wrote:
>>
>>> That's true but irrelevant to my point, which was to counter the
>>> assertion that mutable types can always be assumed to be able to perform
>>> operations in-place.
>>
>> "Always"? Not so fast.
>>
>> This is Python. We have freedom to abuse nearly everything, and if you
>> want to shoot yourself in the foot, you can. With the exception of a
>> handful of things which cannot be overridden (e.g. None, numeric
>> literals, syntax) you cannot strictly assume anything about anything.
>> Python does not enforce that iterators raise StopIteration when empty, or
>> that indexing beyond the boundaries of a sequence raises IndexError, or
>> that __setitem__ of a mapping sets the key and value, or that __len__
>> returns a length.
>
> Thank you; you've stated my point more succinctly than I did.
>
>> Augmented assignment is no different. The docs describe the intention of
>> the designers and the behaviour of the classes that they control, so with
>> standard built-in classes like int, str, list, tuple etc. you can safely
>> assume that mutable types will perform the operation in place and
>> immutable types won't, but with arbitrary types from some arbitrarily
>> eccentric or twisted programmer, who knows what it will do?
>
> This got me curious about how consistent the standard library is about
> this exactly, so I did some grepping.  In the standard library there
> are 5 mutable types that support concatenation that I was able to
> find: list, deque, array, bytearray, and Counter.  There are none that
> support addition, which I find interesting in that the language
> provides hooks for in-place addition but never uses them itself.
>
> All of the classes above appear to follow the rule that if you can
> concatenate an operand, you can in-place concatenate the same operand.
>   The converse however does not hold:  list.__iadd__ and
> Counter.__iadd__ are both more permissive in what types they will
> accept than their __add__ counterparts, and especially interesting to
> me is that deque implements __iadd__ but does not implement __add__ at
> all.  This last in particular seems to support the assertion that +=
> should be viewed more as a shorthand for an in-place operation, less
> as an equivalent for x = x + y.
>
>>>> l = [1,2,3]
>>>> l + (4,5,6)
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
> TypeError: can only concatenate list (not "tuple") to list
>>>> l += (4,5,6)
>>>> l
> [1, 2, 3, 4, 5, 6]

Like it or not, one should actually think of 'somelist += iterable' as 
equivalent to 'somelist.extend(iterable)'.  Without looking at the C 
code, I  suspect that the latter is the internal implementation. 
Collections.deque also has .extend. Collections.Counter has .update and 
that is += seems to be doing.


>>>> c = collections.Counter('mississippi')
>>>> c + collections.Counter('alabama')
> Counter({'s': 4, 'a': 4, 'i': 4, 'p': 2, 'm': 2, 'b': 1, 'l': 1})
>>>> c + dict({'a': 4, 'l': 1, 'b': 1, 'm': 1})
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
> TypeError: unsupported operand type(s) for +: 'Counter' and 'dict'
>>>> c += dict({'a': 4, 'l': 1, 'b': 1, 'm': 1})
>>>> c
> Counter({'s': 4, 'a': 4, 'i': 4, 'p': 2, 'm': 2, 'b': 1, 'l': 1})
>
>>>> d = collections.deque([1,2,3])
>>>> d += [4,5,6]
>>>> d
> deque([1, 2, 3, 4, 5, 6])
>>>> d + [7,8,9]
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
> TypeError: unsupported operand type(s) for +: 'collections.deque' and 'list'
>>>> d.__add__
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
> AttributeError: 'collections.deque' object has no attribute '__add__'
>


-- 
Terry Jan Reedy



From tjreedy at udel.edu  Wed Mar 12 22:27:07 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 12 Mar 2014 22:27:07 -0400
Subject: unittest weirdness
In-Reply-To: <53207E0D.2060604@stoneleaf.us>
References: <mailman.8062.1394573210.18130.python-list@python.org>
 <lfo1qj$3m3$1@reader1.panix.com> <lfokoh$3q3$1@ger.gmane.org>
 <mailman.8082.1394620172.18130.python-list@python.org>
 <roy-66F336.09444712032014@news.panix.com> <53207E0D.2060604@stoneleaf.us>
Message-ID: <lfr521$fnt$1@ger.gmane.org>

On 3/12/2014 11:32 AM, Ethan Furman wrote:

> I strongly suspect it's memory.  When I originally wrote the code I
> tried to include six months worth of EoM data, but had to back it down
> to three as my process kept mysteriously dying at four or more months.
> There must be waaaaaaay too much stuff being kept alive by the stack
> traces of the failed tests.

There is an issue or two about unittest not releasing memory. Also, 
modules are not cleared from sys.modules, so anything accessible from 
global scope is kept around.

-- 
Terry Jan Reedy



From cs at zip.com.au  Wed Mar 12 22:49:27 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Thu, 13 Mar 2014 13:49:27 +1100
Subject: Save to a file, but avoid overwriting an existing file
In-Reply-To: <85zjkvrlpc.fsf@benfinney.id.au>
References: <85zjkvrlpc.fsf@benfinney.id.au>
Message-ID: <20140313024927.GA8841@cskk.homeip.net>

On 13Mar2014 11:22, Ben Finney <ben+python at benfinney.id.au> wrote:
> Cameron Simpson <cs at zip.com.au> writes:
> > Therefore you need to continue _only_ if you get EEXIST. Otherwise
> > abort.
> 
> If you target Python 3.3 or later, you can catch ?FileExistsError?
> <URL:http://docs.python.org/3/library/exceptions.html#FileExistsError>
> which is far simpler than messing around with ?errno? values.

Yes and no.

Firstly, we Old Farts find these new ways confusing:-)

Secondly, and perhaps more importantly, if I were using the O_EXCL
et al constants in a call to os.open as the OP is doing, I would
want to be equally picky about what I recognise in the exception;
I _want_ to use error explicitly. In particular, the behaviour of
"os.open" is pretty much a bare metal call to the POSIX "open(2)"
OS interface, and so I want my response to be framed directly in
terms of the documented error responses for that API. Thus, errno
values.

Finally, if I were grouping my responses to the exception by type
and perhaps performing a few different actions depending on the
error, then the new class hierachy is a good way to do it. But for
this instance, IMO, we're catching exactly one failure mode as
"retry with another name" and reraising anything else. So I don't
find an errno test any less readable that a class comparison, and
it still feels more precise to me.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

The road less traveled is FASTER !!
        - Luc Marcouiller, marcouil at ireq.hydro.qc.ca


From tjreedy at udel.edu  Wed Mar 12 22:54:55 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 12 Mar 2014 22:54:55 -0400
Subject: What does gc.get_objects() return?
In-Reply-To: <lfqcr8$249$1@ger.gmane.org>
References: <lfqcr8$249$1@ger.gmane.org>
Message-ID: <lfr6m6$vcv$1@ger.gmane.org>

On 3/12/2014 3:34 PM, Jurko Gospodneti? wrote:

>    I was wondering if someone could explain gc.get_objects() in a bit
> more detail to me.
>
>    Does it return a list of 'all objects known to Python'? Only some of
> them? Which does it return? Which it does not?

This took about 10 seconds.

 >>> import gc
 >>> help(gc.get_objects)
Help on built-in function get_objects in module gc:

get_objects(...)
     get_objects() -> [...]

     Return a list of objects tracked by the collector (excluding the 
list returned).
---

Now, what object does gc track? CPython answer: objects that could be 
involved in and kept alive by reverence cycles and therefore not deleted 
when not needed by reference counting alone. Object instances, numbers, 
and strings cannot be involved in reference cycles, as there are no user 
settable references. Tuples can be:

a = []
b = (a,)
a[0] = b

A tuple of, for instance, ints would not need to be tracked, but if it 
is, someone probably decided that the cost of checking is not worth the 
benefit. Details are subject to change with versions. In 3.4, gc can 
break cycles of objects with delete methods, whereas they previously 
waiting until program shutdown. Some year ago, I remember a suggestion 
to turn off gc while creating lots of tuples that did not need to be 
tracked, but I do not know if that is still useful.

-- 
Terry Jan Reedy




From rustompmody at gmail.com  Wed Mar 12 23:09:25 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Wed, 12 Mar 2014 20:09:25 -0700 (PDT)
Subject: Deep vs. shallow copy?
In-Reply-To: <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <0852919b-e5ac-42cc-b30f-f465a144e24e@googlegroups.com>

On Thursday, March 13, 2014 4:37:53 AM UTC+5:30, Steven D'Aprano wrote:
> On Wed, 12 Mar 2014 15:29:59 +0000, Alex van der Spek wrote:

> > Having been taught programming in Algol60 Python still defeats me at
> > times! Particularly since Algol60 wasn't very long lived and what came
> > thereafter (FORTRAN) much worse.


> I'm not really familiar with Algol, but I do know Pascal, and you should 
> think of the append method to be like a Pascal procedure. Because Python 
> doesn't have true procedures, it follows the convention that returning 
> the special object None signals the intention to return nothing at all. 
> Hence your example below:

Yes... Algol I dont know. But to the extent that it corresponds to
Pascal the following may help.

Pascal is remarkably clean and cleaner than what came before -- Lisp
-- and after -- C, all its derivatives, python... almost everything.

First off there are expressions and statements, and no messing with
the distinction.  C started laissez-faire. No void, just default
functions intended to be used as procedures to int.  This was
problematic to enough people that void was introduced soon enough.

But its still messy:
An assignment like x = 3 is both an expression and (like) a statement.
It is mostly used as a statement by appending a semicolon.
It can also be used as an expression as in y = x = 3.

Try explaining this to a first year class and you'd know what a mess it is.
For the most part if you think youve got it you probably havent.

Python is in some respects worse than C, in some better.

Its better in that assignment statements are not re-purposeable as
expressions. Its worse in that procedures are simulated by None
returning functions -- this means syntax errors which C would give
when using a void function as an expression, you wont get in python.

On the whole, whether your language supports it or not, its best to
think of the world as separated into actions and values.

Call the action-world the 'imperative' world.
Call the value-world the 'functional' world ('declarative' would be
better but 'functional' is too entrenched).

[Following table meant to be read with fixed (courier) font]

|                         | Imperative | Functional          |
| Language entity         | Statement  | Expression          |
| Denote (and think with) | Action     | Value               |
| Abstracted into         | Procedure  | Function            |
| Atoms are               | Assignment | Constant/Variable   |
| Data Structures         | Mutable    | Immutable           |
| Loop primitive          | Recursion  | Iteration           |
| World is                | In time    | Timeless (Platonic) |

Generally mixing these two worlds is necessary for any non-trivial
programming but is commonly problematic.

Your error was to use a functional form -- list comprehension -- and
embed an imperative construct -- row.append -- into that.  This is
always a gaffe

Legal mixing is done thus
Expression -> Statement by putting the expression on the rhs of an assignment
Statement -> Expression by putting the statement(s) into a function

While most programmers think this unproblematic, Backus' widely-cited
Turing Award lecture is devoted to showing why this is a problem
http://www.thocp.net/biographies/papers/backus_turingaward_lecture.pdf

For an old Algol/Fortran programmer it may be a worthwhile read considering
Backus invented Fortran :-)


From chris at simplistix.co.uk  Thu Mar 13 02:22:01 2014
From: chris at simplistix.co.uk (Chris Withers)
Date: Thu, 13 Mar 2014 06:22:01 +0000
Subject: SMTPHandler and mail subject
In-Reply-To: <f92d95e9-8997-4040-a8b8-d2404fe04798@googlegroups.com>
References: <4b23c949-12eb-444b-a950-c830ace83ca9@googlegroups.com>
 <mailman.8081.1394620139.18130.python-list@python.org>
 <f92d95e9-8997-4040-a8b8-d2404fe04798@googlegroups.com>
Message-ID: <53214E89.2080101@simplistix.co.uk>

If you want a much more fully-featured mail handler for the standard 
logging framework, there's this:

https://pypi.python.org/pypi/mailinglogger/3.8.0

cheers,

Chris

On 12/03/2014 12:25, eras.rasmuson at gmail.com wrote:
>
> It works. Thank you :)
>
> ----
> Eras
>

-- 
Simplistix - Content Management, Batch Processing & Python Consulting
            - http://www.simplistix.co.uk


From richard at pyweek.org  Thu Mar 13 06:58:52 2014
From: richard at pyweek.org (Richard Jones)
Date: Thu, 13 Mar 2014 21:58:52 +1100
Subject: [ANN] PyWeek 18 will run in May (11th to 18th)
Message-ID: <CAHrZfZD+LfZoxm+63ouq798gGECRdR8T6BS8r2YyXjhXgTkwdQ@mail.gmail.com>

Hi all,

The Python Game Programming Challenge <http://pyweek.org/> will run
its 18th challenge from the 11th to the 18th of May.

The PyWeek challenge:

1. Invites entrants to write a game in one week from scratch either as
an individual or in a team,
2. Is intended to be challenging and fun,
3. Will increase the public body of game tools, code and expertise,
4. Will let a lot of people actually finish a game, and
5. May inspire new projects (with ready made teams!)

Check out the help page for how to compete (and prepare) and the
growing resources message board post:

   http://pyweek.org/s/help/
   http://pyweek.org/d/4008/



      Richard
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-list/attachments/20140313/5dd99d44/attachment.html>

From hobson42 at gmail.com  Thu Mar 13 07:38:22 2014
From: hobson42 at gmail.com (Ian)
Date: Thu, 13 Mar 2014 11:38:22 +0000
Subject: Deep vs. shallow copy?
In-Reply-To: <0852919b-e5ac-42cc-b30f-f465a144e24e@googlegroups.com>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <0852919b-e5ac-42cc-b30f-f465a144e24e@googlegroups.com>
Message-ID: <532198AE.10509@gmail.com>

On 13/03/2014 03:09, Rustom Mody wrote:
> Call the action-world the 'imperative' world.
> Call the value-world the 'functional' world ('declarative' would be
> better but 'functional' is too entrenched).
>
> [Following table meant to be read with fixed (courier) font]
>
> |                         | Imperative | Functional          |
> | Language entity         | Statement  | Expression          |
> | Denote (and think with) | Action     | Value               |
> | Abstracted into         | Procedure  | Function            |
> | Atoms are               | Assignment | Constant/Variable   |
> | Data Structures         | Mutable    | Immutable           |
> | Loop primitive          | Recursion  | Iteration           |
> | World is                | In time    | Timeless (Platonic) |
Small typo I think in that the looping Primitives are switched about?

Regards

Ian

-- 
Ian Hobson
29 Manorfield Close, Northampton NN3 9SL,
Tel: 01604 513875
Preparing eBooks for Kindle and ePub formats to give the best reader experience.



From roy at panix.com  Thu Mar 13 07:44:27 2014
From: roy at panix.com (Roy Smith)
Date: Thu, 13 Mar 2014 07:44:27 -0400
Subject: Deep vs. shallow copy?
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-493F5F.07442713032014@news.panix.com>

In article <5320e8c9$0$29994$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> Because Python doesn't have true procedures

What do you mean by "true procedure"?  Are you just talking about 
subroutines that don't return any value, i.e. fortran's SUBROUTINE vs. 
FUNCTION?


From marko at pacujo.net  Thu Mar 13 08:27:48 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 13 Mar 2014 14:27:48 +0200
Subject: Deep vs. shallow copy?
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
Message-ID: <87y50el1vf.fsf@elektro.pacujo.net>

Roy Smith <roy at panix.com>:

>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>
>> Because Python doesn't have true procedures
>
> What do you mean by "true procedure"? Are you just talking about
> subroutines that don't return any value, i.e. fortran's SUBROUTINE vs.
> FUNCTION?

Ah, the "no true procedure" argument:

 - No true procedure returns a value.

 - That's false. Python's procedures return None.

 - They are not true procedures.


Marko


From jurko.gospodnetic at pke.hr  Thu Mar 13 08:36:48 2014
From: jurko.gospodnetic at pke.hr (=?UTF-8?B?SnVya28gR29zcG9kbmV0acSH?=)
Date: Thu, 13 Mar 2014 13:36:48 +0100
Subject: What does gc.get_objects() return?
In-Reply-To: <CALwzidnbry5nJg0aLEr7yCcDmykr2QSeEcJ8NtVjRvj_4ce5rQ@mail.gmail.com>
References: <lfqcr8$249$1@ger.gmane.org>
 <5320BD3F.5030509@mrabarnett.plus.com> <lfqjgu$kug$1@ger.gmane.org>
 <CAPTjJmqdKZ6qDQ+PZAdxVF-hKN=txKh35ga_C451C2z_hpZZAA@mail.gmail.com>
 <CALwzidn4o-z=wvGS89-WvL=DivBm0T3GSbTV0qcUJFE5zmo2XA@mail.gmail.com>
 <CALwzidnbry5nJg0aLEr7yCcDmykr2QSeEcJ8NtVjRvj_4ce5rQ@mail.gmail.com>
Message-ID: <lfs8og$f95$1@ger.gmane.org>

   Hi.

On 12.3.2014. 23:40, Ian Kelly wrote:
>> Or is it?
>>
>>>>> a = 1,2,3
>>>>> gc.is_tracked(a)
>> True
>>>>> gc.collect()
>> 0
>>>>> gc.is_tracked(a)
>> False

   Ufff.. nice one :-D

   Best regards,
     Jurko Gospodneti?




From jurko.gospodnetic at pke.hr  Thu Mar 13 08:38:39 2014
From: jurko.gospodnetic at pke.hr (=?UTF-8?B?SnVya28gR29zcG9kbmV0acSH?=)
Date: Thu, 13 Mar 2014 13:38:39 +0100
Subject: What does gc.get_objects() return?
In-Reply-To: <lfr6m6$vcv$1@ger.gmane.org>
References: <lfqcr8$249$1@ger.gmane.org> <lfr6m6$vcv$1@ger.gmane.org>
Message-ID: <lfs8s0$f95$2@ger.gmane.org>

   Hi.

On 13.3.2014. 3:54, Terry Reedy wrote:
> On 3/12/2014 3:34 PM, Jurko Gospodneti? wrote:
>
>>    I was wondering if someone could explain gc.get_objects() in a bit
>> more detail to me.
>>
>>    Does it return a list of 'all objects known to Python'? Only some of
>> them? Which does it return? Which it does not?
>
> [...detailed explanation snipped...]

   Thank you very much for taking the time to explain it all in detail.

   Best regards,
     Jurko Gospodneti?



From gordon at panix.com  Thu Mar 13 10:43:05 2014
From: gordon at panix.com (John Gordon)
Date: Thu, 13 Mar 2014 14:43:05 +0000 (UTC)
Subject: DB API question - where is a stored procedure's return value?
References: <CANc-5Uz98mTCjUuk_yOHqWeZRwp6JnTCagTQ=bzobhtWAceKxg@mail.gmail.com>
 <CALwzidm0GJ37JTjUUGPPgEXnZoh0ck08B7i2H4SZXXD1VyDcbA@mail.gmail.com>
 <mailman.8114.1394666303.18130.python-list@python.org>
Message-ID: <lfsg5p$e1a$1@reader1.panix.com>

In <mailman.8114.1394666303.18130.python-list at python.org> Petite Abeille <petite.abeille at gmail.com> writes:


> Alternatively=85 if it=92s really a function=85 wrap it in a select =
> statement=85 such as:

> select foo() as value from dual

That will get the return value into an SQL variable, but the OP wanted
to know how to fetch it from python code.

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon at panix.com    watch 'House', or a real serial killer to watch 'Dexter'.



From simiasaro at gmail.com  Thu Mar 13 10:52:25 2014
From: simiasaro at gmail.com (simiasaro at gmail.com)
Date: Thu, 13 Mar 2014 07:52:25 -0700 (PDT)
Subject: TypeError: can't multiply sequence by non-int of type 'tuple'
In-Reply-To: <e84de2c2-5333-42ae-ae22-cf628c177ae1@googlegroups.com>
References: <e84de2c2-5333-42ae-ae22-cf628c177ae1@googlegroups.com>
Message-ID: <bdcc37eb-d7ca-42c7-aa0e-9a317d366dae@googlegroups.com>

On Friday, February 21, 2014 1:31:53 AM UTC-5, Jaydeep Patil wrote:
> HI,
> 
> 
> 
> I have a tuple. I need to make sqaure of elements of tuple and after that i want add all suared tuple elements for total. When i trying to do it, below error came.
> 
> 
> 
> 
> 
> Code:
> 
> seriesxlist1 = ((0.0,), (0.01,), (0.02,), (0.03,), (0.04,), (0.05,), (0.06,), (0.07,), (0.08,), (0.09,), (0.1,), (0.11,))
> 
> 
> 
> x2 = [x * x for x in seriesxlist1];
> 
> 
> 
> Error:
> 
> Traceback (most recent call last):
> 
>   File "<pyshell#188>", line 1, in <module>
> 
>     x2 = [x * x for x in seriesxlist1];
> 
> TypeError: can't multiply sequence by non-int of type 'tuple'
> 
> 
> 
> 
> 
> 
> 
> Please suggest me solution.

You may want to identify which of the tuple value you want to multiply, especially since the tuple has only one value:
x2 = [x[0] * x[0] for x in seriesxlist1]

Then, you can add the values in the list:
sum(x2)

or the quickest way:
sum(x[0] * x[0] for x in seriesxlist1)


From skip at pobox.com  Thu Mar 13 11:14:36 2014
From: skip at pobox.com (Skip Montanaro)
Date: Thu, 13 Mar 2014 10:14:36 -0500
Subject: DB API question - where is a stored procedure's return value?
In-Reply-To: <lfsg5p$e1a$1@reader1.panix.com>
References: <CANc-5Uz98mTCjUuk_yOHqWeZRwp6JnTCagTQ=bzobhtWAceKxg@mail.gmail.com>
 <CALwzidm0GJ37JTjUUGPPgEXnZoh0ck08B7i2H4SZXXD1VyDcbA@mail.gmail.com>
 <mailman.8114.1394666303.18130.python-list@python.org>
 <lfsg5p$e1a$1@reader1.panix.com>
Message-ID: <CANc-5Ux7HQCegMWxWS00YmKdV=cU+3KyXKn-BAPAP1MngKb-Cw@mail.gmail.com>

Thanks for the responses. We eventually figured out there appears to
be a bug in the latest version of the python-sybase module (at least
in 0.40, probably in 0.39 as well). It was actually detecting
CS_STATUS_RESULT coming from the server and responding appropriately,
however it was assigning the actual status result to a local variable
instead of an attribute of the Cursor instance. Testing a fix now.

Skip


From rustompmody at gmail.com  Thu Mar 13 11:28:47 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 13 Mar 2014 08:28:47 -0700 (PDT)
Subject: Deep vs. shallow copy?
In-Reply-To: <mailman.8125.1394710730.18130.python-list@python.org>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <0852919b-e5ac-42cc-b30f-f465a144e24e@googlegroups.com>
 <mailman.8125.1394710730.18130.python-list@python.org>
Message-ID: <04d2454f-4a22-482c-9d41-f2e1d2032675@googlegroups.com>

On Thursday, March 13, 2014 5:08:22 PM UTC+5:30, Ian wrote:
> On 13/03/2014 03:09, Rustom Mody wrote:
> > Call the action-world the 'imperative' world.
> > Call the value-world the 'functional' world ('declarative' would be
> > better but 'functional' is too entrenched).
> > [Following table meant to be read with fixed (courier) font]
> > |                         | Imperative | Functional          |
> > | Language entity         | Statement  | Expression          |
> > | Denote (and think with) | Action     | Value               |
> > | Abstracted into         | Procedure  | Function            |
> > | Atoms are               | Assignment | Constant/Variable   |
> > | Data Structures         | Mutable    | Immutable           |
> > | Loop primitive          | Recursion  | Iteration           |
> > | World is                | In time    | Timeless (Platonic) |
> Small typo I think in that the looping Primitives are switched about?

Heh! I was hesitating to put that line at all: For one thing its a
hackneyed truth in the non-FP community. For another, in practical
Haskell, use of frank recursion is regarded as as sign of programming
immaturity:

http://www.willamette.edu/~fruehr/haskell/evolution.html

So I guess I ended up typing it in the wrong order!


From rosuav at gmail.com  Thu Mar 13 13:01:02 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 14 Mar 2014 04:01:02 +1100
Subject: DB API question - where is a stored procedure's return value?
In-Reply-To: <lfsg5p$e1a$1@reader1.panix.com>
References: <CANc-5Uz98mTCjUuk_yOHqWeZRwp6JnTCagTQ=bzobhtWAceKxg@mail.gmail.com>
 <CALwzidm0GJ37JTjUUGPPgEXnZoh0ck08B7i2H4SZXXD1VyDcbA@mail.gmail.com>
 <mailman.8114.1394666303.18130.python-list@python.org>
 <lfsg5p$e1a$1@reader1.panix.com>
Message-ID: <CAPTjJmqRgUGp=X5O_1pnJhK0=raZj7ALUg0DVsfhuCc0AcexuA@mail.gmail.com>

On Fri, Mar 14, 2014 at 1:43 AM, John Gordon <gordon at panix.com> wrote:
>> select foo() as value from dual
>
> That will get the return value into an SQL variable, but the OP wanted
> to know how to fetch it from python code.

In theory, that should produce a one-row-one-column SELECT result,
which can then be retrieved as such. (I say "in theory" because not
all back-end databases support the "from dual" notation - which, by
the way, I find extremely odd; what's 'dual' about it?)

ChrisA


From random832 at fastmail.us  Thu Mar 13 13:22:08 2014
From: random832 at fastmail.us (random832 at fastmail.us)
Date: Thu, 13 Mar 2014 13:22:08 -0400
Subject: DB API question - where is a stored procedure's return value?
In-Reply-To: <CAPTjJmqRgUGp=X5O_1pnJhK0=raZj7ALUg0DVsfhuCc0AcexuA@mail.gmail.com>
References: <CANc-5Uz98mTCjUuk_yOHqWeZRwp6JnTCagTQ=bzobhtWAceKxg@mail.gmail.com>
 <CALwzidm0GJ37JTjUUGPPgEXnZoh0ck08B7i2H4SZXXD1VyDcbA@mail.gmail.com>
 <mailman.8114.1394666303.18130.python-list@python.org>
 <lfsg5p$e1a$1@reader1.panix.com>
 <CAPTjJmqRgUGp=X5O_1pnJhK0=raZj7ALUg0DVsfhuCc0AcexuA@mail.gmail.com>
Message-ID: <1394731328.29875.94134461.087FF85B@webmail.messagingengine.com>

On Thu, Mar 13, 2014, at 13:01, Chris Angelico wrote:
> On Fri, Mar 14, 2014 at 1:43 AM, John Gordon <gordon at panix.com> wrote:
> >> select foo() as value from dual
> >
> > That will get the return value into an SQL variable, but the OP wanted
> > to know how to fetch it from python code.
> 
> In theory, that should produce a one-row-one-column SELECT result,
> which can then be retrieved as such. (I say "in theory" because not
> all back-end databases support the "from dual" notation - which, by
> the way, I find extremely odd; what's 'dual' about it?)

DUAL is an Oracle thing. It used to have two rows, in order to be used
to duplicate results by doing a cartesian join to it. At some point,
that was removed, but the name stuck.

Most other servers allow SELECT without FROM.


From random832 at fastmail.us  Thu Mar 13 13:25:08 2014
From: random832 at fastmail.us (random832 at fastmail.us)
Date: Thu, 13 Mar 2014 13:25:08 -0400
Subject: Deep vs. shallow copy?
In-Reply-To: <04d2454f-4a22-482c-9d41-f2e1d2032675@googlegroups.com>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <0852919b-e5ac-42cc-b30f-f465a144e24e@googlegroups.com>
 <mailman.8125.1394710730.18130.python-list@python.org>
 <04d2454f-4a22-482c-9d41-f2e1d2032675@googlegroups.com>
Message-ID: <1394731508.30917.94137029.2E73EB99@webmail.messagingengine.com>

On Thu, Mar 13, 2014, at 11:28, Rustom Mody wrote:
> Heh! I was hesitating to put that line at all: For one thing its a
> hackneyed truth in the non-FP community. For another, in practical
> Haskell, use of frank recursion is regarded as as sign of programming
> immaturity:

And IIRC Lisp and Scheme have loop macros (whose semantics are more like
a goal seek than iteration IIRC).


From rosuav at gmail.com  Thu Mar 13 13:32:39 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 14 Mar 2014 04:32:39 +1100
Subject: DB API question - where is a stored procedure's return value?
In-Reply-To: <1394731328.29875.94134461.087FF85B@webmail.messagingengine.com>
References: <CANc-5Uz98mTCjUuk_yOHqWeZRwp6JnTCagTQ=bzobhtWAceKxg@mail.gmail.com>
 <CALwzidm0GJ37JTjUUGPPgEXnZoh0ck08B7i2H4SZXXD1VyDcbA@mail.gmail.com>
 <mailman.8114.1394666303.18130.python-list@python.org>
 <lfsg5p$e1a$1@reader1.panix.com>
 <CAPTjJmqRgUGp=X5O_1pnJhK0=raZj7ALUg0DVsfhuCc0AcexuA@mail.gmail.com>
 <1394731328.29875.94134461.087FF85B@webmail.messagingengine.com>
Message-ID: <CAPTjJmra7rHGE9af5NK_YRtxQZeKY9oOdy8Ft1nTn7-Gtn4LuA@mail.gmail.com>

On Fri, Mar 14, 2014 at 4:22 AM,  <random832 at fastmail.us> wrote:
> DUAL is an Oracle thing. It used to have two rows, in order to be used
> to duplicate results by doing a cartesian join to it. At some point,
> that was removed, but the name stuck.
>
> Most other servers allow SELECT without FROM.

Yeah, I usually use PostgreSQL which does. I don't remember what DB2
has. MySQL I think requires either DUAL or an actual real table.

ChrisA


From ian.g.kelly at gmail.com  Thu Mar 13 14:40:58 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 13 Mar 2014 12:40:58 -0600
Subject: Balanced trees
In-Reply-To: <87zjkyq7nr.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <mailman.8013.1394471845.18130.python-list@python.org>
 <87zjkyq7nr.fsf@elektro.pacujo.net>
Message-ID: <CALwzid=2_HfsOd2PCapCht20hO1T7RBoS7FCmngaUo0rNrc=_Q@mail.gmail.com>

On Mon, Mar 10, 2014 at 11:34 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> The main thing is there are use cases where order is essential. That's
> why I have had to implement the AVL tree in Python myself. No biggie,
> but a C implementation would probably be much faster. Also, a standard
> version would likely be reviewed and tested better and have all Pythonic
> accessors in place.

That last is actually quite easy to achieve, especially using the
built-in ABCs.  Just subclass from collections.MutableMapping and
implement __len__, __iter__, __getitem__, __setitem__ and __delitem__;
and default implementations of the rest will be mixed in for you.  Or
you can override those with optimized implementations.


From jcasale at activenetwerx.com  Thu Mar 13 17:24:15 2014
From: jcasale at activenetwerx.com (Joseph L. Casale)
Date: Thu, 13 Mar 2014 21:24:15 +0000
Subject: asyncio question
Message-ID: <5ff86b234ac640ab8b7ee3f26e9aa8dc@exch.activenetwerx.com>

I have a portion of code I need to speed up, there are 3 api calls to an external system
where the first enumerates a large collection of objects I then loop through and perform
two additional api calls each. The first call is instant, the second and third per object are
very slow. Currently after accumulating all the data I write the relevant data into a database.

I have the ability to hold all this in memory and dump it once fully accumulated, so performing
the second and third call in parallel with fixed batches would be great,

I took a look at coroutines and some skeleton code worked fine, but I am not sure how to
perform the acquisition in fixed groups like I might for example with multiprocessing and
a pool of workers.

Anyone done something like this or have an opinion?

Thanks,
jlc

From steve+comp.lang.python at pearwood.info  Thu Mar 13 19:31:50 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 13 Mar 2014 23:31:50 GMT
Subject: Deep vs. shallow copy?
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
Message-ID: <53223fe6$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 13 Mar 2014 07:44:27 -0400, Roy Smith wrote:

> In article <5320e8c9$0$29994$c3e8da3$5496439d at news.astraweb.com>,
>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
> 
>> Because Python doesn't have true procedures
> 
> What do you mean by "true procedure"?  Are you just talking about
> subroutines that don't return any value, i.e. fortran's SUBROUTINE vs.
> FUNCTION?


Yes. If somebody wants to argue that the word "procedure" can mean 
something else in other contexts, I won't argue, I'll just point out that 
in the context of my post I had just mentioned Pascal procedures, which 
don't return a value.





-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Thu Mar 13 19:41:03 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 13 Mar 2014 23:41:03 GMT
Subject: Deep vs. shallow copy?
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
 <87y50el1vf.fsf@elektro.pacujo.net>
Message-ID: <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 13 Mar 2014 14:27:48 +0200, Marko Rauhamaa wrote:

> Roy Smith <roy at panix.com>:
> 
>>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>>
>>> Because Python doesn't have true procedures
>>
>> What do you mean by "true procedure"? Are you just talking about
>> subroutines that don't return any value, i.e. fortran's SUBROUTINE vs.
>> FUNCTION?
> 
> Ah, the "no true procedure" argument:
> 
>  - No true procedure returns a value.
> 
>  - That's false. Python's procedures return None.

Are you trolling again? 

I'm sure that you know quite well that Python doesn't have a procedure 
type. It uses a single keyword, def, for creating both functions and 
functions-that-return-None.

We should all agree that functions-that-return-None are used for the same 
purpose as procedures, but they are still functions, and they have a 
return result, namely None. If you don't believe me, believe Python:

py> def func():
...     return 42
...
py> def proc():
...     pass
...
py> type(func)
<class 'function'>
py> type(proc)
<class 'function'>
py> repr(proc())
'None'

In languages with procedures, that last line would be an error (either at 
compile-time, or run-time) since a procedure wouldn't return anything to 
use as argument to repr. But I'm sure that you know that.


>  - They are not true procedures.

Correct. They are functions that return None, rather than a subroutine 
that doesn't have any return value at all. But I'm sure you know that.





-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Thu Mar 13 19:55:44 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 14 Mar 2014 10:55:44 +1100
Subject: Deep vs. shallow copy?
In-Reply-To: <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
 <87y50el1vf.fsf@elektro.pacujo.net>
 <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmpufKDDnWRBusutSR4hdxVu8LvmBp9SXjYJmBjy7rx+4Q@mail.gmail.com>

On Fri, Mar 14, 2014 at 10:41 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Are you trolling again?
>
> I'm sure that you know quite well that Python doesn't have a procedure
> type. It uses a single keyword, def, for creating both functions and
> functions-that-return-None.

I'm going to troll for a moment and give you a function that has no
return value.

def procedure():
    raise Exception

But seriously, this is something that some functions do when they need
to distinguish between returning something and not returning anything.
Look at a dictionary's subscripting (which is effectively a function
call):

>>> x={1:2}
>>> x[1]
2
>>> x[3]
Traceback (most recent call last):
  File "<pyshell#17>", line 1, in <module>
    x[3]
KeyError: 3

It can't return None to indicate "there was no such key in the
dictionary", so it raises instead. There's only one way for a Python
function to not have a return value: it has to not return.

ChrisA


From steve+comp.lang.python at pearwood.info  Thu Mar 13 19:57:47 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 13 Mar 2014 23:57:47 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <mailman.8013.1394471845.18130.python-list@python.org>
 <87zjkyq7nr.fsf@elektro.pacujo.net>
Message-ID: <532245fa$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Mon, 10 Mar 2014 19:34:48 +0200, Marko Rauhamaa wrote:

>> With a high level language like Python, using the provided hash table
>> will almost always cream any hand-built tree, no matter how
>> advantageous the data is to the tree.
> 
> The main thing is there are use cases where order is essential. That's
> why I have had to implement the AVL tree in Python myself.

from collections import OrderedDict

gives you a fast, ordered mapping. In this case, the order is that of 
insertion order. If you want sort order instead, for "small" amounts of 
data, say below a million or ten million items, you're likely to have 
acceptable if not superior results by just sorting them items when and as 
needed.

Otherwise, I expect that following the basic technique of OrderedDict, 
and building your data structure from a dict and an associated list, 
keeping the two in sync, will be faster than a pure Python implementation 
of an AVL tree. But of course only testing it will make that clear.

http://code.activestate.com/recipes/576693-ordered-dictionary-for-py24/

Modifying the above recipe to keep items in something other than 
insertion order is left as an exercise.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ian.g.kelly at gmail.com  Thu Mar 13 20:08:47 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 13 Mar 2014 18:08:47 -0600
Subject: Deep vs. shallow copy?
In-Reply-To: <CAPTjJmpufKDDnWRBusutSR4hdxVu8LvmBp9SXjYJmBjy7rx+4Q@mail.gmail.com>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
 <87y50el1vf.fsf@elektro.pacujo.net>
 <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmpufKDDnWRBusutSR4hdxVu8LvmBp9SXjYJmBjy7rx+4Q@mail.gmail.com>
Message-ID: <CALwzidkG1GdOH5PQDEzaj76aNW2OWCMXYkg4_xth38jtnvBJ9g@mail.gmail.com>

On Thu, Mar 13, 2014 at 5:55 PM, Chris Angelico <rosuav at gmail.com> wrote:
> I'm going to troll for a moment and give you a function that has no
> return value.
>
> def procedure():
>     raise Exception

>>> import dis
>>> dis.dis(procedure)
  2           0 LOAD_GLOBAL              0 (Exception)
              3 RAISE_VARARGS            1
              6 LOAD_CONST               0 (None)
              9 RETURN_VALUE
>>> def get_procedure_return_value():
...     """Returns the return value of procedure()."""
...     return procedure.__code__.co_consts[0]
...
>>> print(get_procedure_return_value())
None

Look, there it is!


From rosuav at gmail.com  Thu Mar 13 20:22:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 14 Mar 2014 11:22:43 +1100
Subject: Deep vs. shallow copy?
In-Reply-To: <CALwzidkG1GdOH5PQDEzaj76aNW2OWCMXYkg4_xth38jtnvBJ9g@mail.gmail.com>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
 <87y50el1vf.fsf@elektro.pacujo.net>
 <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmpufKDDnWRBusutSR4hdxVu8LvmBp9SXjYJmBjy7rx+4Q@mail.gmail.com>
 <CALwzidkG1GdOH5PQDEzaj76aNW2OWCMXYkg4_xth38jtnvBJ9g@mail.gmail.com>
Message-ID: <CAPTjJmrFrbkziw35qDhMBBe3=7KsqK5HqxWXO-JWemQ_t3fZMQ@mail.gmail.com>

On Fri, Mar 14, 2014 at 11:08 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Thu, Mar 13, 2014 at 5:55 PM, Chris Angelico <rosuav at gmail.com> wrote:
>> I'm going to troll for a moment and give you a function that has no
>> return value.
>>
>> def procedure():
>>     raise Exception
>
>>>> import dis
>>>> dis.dis(procedure)
>   2           0 LOAD_GLOBAL              0 (Exception)
>               3 RAISE_VARARGS            1
>               6 LOAD_CONST               0 (None)
>               9 RETURN_VALUE

That's a return value in the same way that exec() has a return value
[1]. If somehow the raise fails, it'll return None.

>>>> def get_procedure_return_value():
> ...     """Returns the return value of procedure()."""
> ...     return procedure.__code__.co_consts[0]
> ...
>>>> print(get_procedure_return_value())
> None
>
> Look, there it is!

Succeeds by coincidence. From what I can see, *every* CPython function
has const slot 0 dedicated to None. At least, I haven't been able to
do otherwise.

>>> def function(x):
    return x*2+1

>>> import dis
>>> dis.dis(function)
  2           0 LOAD_FAST                0 (x)
              3 LOAD_CONST               1 (2)
              6 BINARY_MULTIPLY
              7 LOAD_CONST               2 (1)
             10 BINARY_ADD
             11 RETURN_VALUE
>>> function.__code__.co_consts
(None, 2, 1)

Your return value retriever would say it returns None still, but it doesn't.

Trollbridge: you have to pay a troll to cross.

ChrisA

[1] I'm not talking about Python's 'exec' statement, but about the
Unix exec() API, eg execlpe() - see http://linux.die.net/man/3/exec


From chris at simplistix.co.uk  Thu Mar 13 20:25:45 2014
From: chris at simplistix.co.uk (Chris Withers)
Date: Fri, 14 Mar 2014 00:25:45 +0000
Subject: which async framework?
In-Reply-To: <lfnotf$i2a$1@ger.gmane.org>
References: <531E22DF.7030709@simplistix.co.uk> <lflcha$2mf$1@ger.gmane.org>
 <531EC0E6.10402@simplistix.co.uk> <lfnotf$i2a$1@ger.gmane.org>
Message-ID: <53224C89.5050503@simplistix.co.uk>

On 11/03/2014 19:41, Terry Reedy wrote:

>> I suspect I'll just end up cross-posting to the various mailing lists,
>
> Bad idea. Post separately if you must.
>
>  > which I hope won't cause too much offence or kick off any flame wars.
>
> It would do both.

Ye of little faith :-P

I've been pleasantly surprised by the succinct, well reasoned and 
respectful replies from each of the communities!

Chris

-- 
Simplistix - Content Management, Batch Processing & Python Consulting
             - http://www.simplistix.co.uk


From python.list at tim.thechases.com  Thu Mar 13 20:36:34 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Thu, 13 Mar 2014 19:36:34 -0500
Subject: which async framework?
In-Reply-To: <53224C89.5050503@simplistix.co.uk>
References: <531E22DF.7030709@simplistix.co.uk> <lflcha$2mf$1@ger.gmane.org>
 <531EC0E6.10402@simplistix.co.uk> <lfnotf$i2a$1@ger.gmane.org>
 <53224C89.5050503@simplistix.co.uk>
Message-ID: <20140313193634.3767ddfc@bigbox.christie.dr>

On 2014-03-14 00:25, Chris Withers wrote:
> I've been pleasantly surprised by the succinct, well reasoned and 
> respectful replies from each of the communities!

As one who doesn't lurk on the other lists, is there a nice executive
summary of their responses?

-tkc





From izecksohn at yahoo.com  Thu Mar 13 18:36:39 2014
From: izecksohn at yahoo.com (Pedro Izecksohn)
Date: Thu, 13 Mar 2014 15:36:39 -0700 (PDT)
Subject: pickle.dump (obj, conn)
Message-ID: <1394750199.11584.YahooMailNeo@web140104.mail.bf1.yahoo.com>

? Shouldn't pickle.dump (obj, conn) raise an Exception if conn is a TCP connection that was closed by the remote host?
-------------- next part --------------
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From ian.g.kelly at gmail.com  Thu Mar 13 21:26:55 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 13 Mar 2014 19:26:55 -0600
Subject: pickle.dump (obj, conn)
In-Reply-To: <1394750199.11584.YahooMailNeo@web140104.mail.bf1.yahoo.com>
References: <1394750199.11584.YahooMailNeo@web140104.mail.bf1.yahoo.com>
Message-ID: <CALwzidnhr1qzEa0+qN6Zg2KqySwoxB2GsBq7rgsUhmodOZCKig@mail.gmail.com>

On Thu, Mar 13, 2014 at 4:36 PM, Pedro Izecksohn <izecksohn at yahoo.com> wrote:
>   Shouldn't pickle.dump (obj, conn) raise an Exception if conn is a TCP
> connection that was closed by the remote host?

Can you be more specific about what you are doing, what you expect the
result to be, and what the actual result is?

http://www.catb.org/esr/faqs/smart-questions.html#beprecise

If I try using pickle.dump with a socket, I do get an exception, but
perhaps not the one you are looking for:

>>> pickle.dump([1,2,3], sock)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: file must have a 'write' attribute


From steve+comp.lang.python at pearwood.info  Thu Mar 13 21:41:58 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 14 Mar 2014 01:41:58 GMT
Subject: Deep vs. shallow copy?
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
 <87y50el1vf.fsf@elektro.pacujo.net>
 <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8135.1394754947.18130.python-list@python.org>
Message-ID: <53225e65$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Fri, 14 Mar 2014 10:55:44 +1100, Chris Angelico wrote:

> On Fri, Mar 14, 2014 at 10:41 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> Are you trolling again?
>>
>> I'm sure that you know quite well that Python doesn't have a procedure
>> type. It uses a single keyword, def, for creating both functions and
>> functions-that-return-None.
> 
> I'm going to troll for a moment and give you a function that has no
> return value.

Heh, you're not trolling. You're just trying to be pedantic. But not 
pedantic enough... 


> def procedure():
>     raise Exception

This does have a return result, and it is None. It's just that the 
function never reaches the return, it exits early via an exception.

py> from dis import dis
py> dis(procedure)
  2           0 LOAD_GLOBAL              0 (Exception)
              3 RAISE_VARARGS            1
              6 LOAD_CONST               0 (None)
              9 RETURN_VALUE

That *may* be able to be optimized away by a smarter compiler, or perhaps 
it can't be. There may be some technical reason why code objects have to 
end with a return no matter what:

py> dis(compile("func()", "", "exec"))
  1           0 LOAD_NAME                0 (func)
              3 CALL_FUNCTION            0 (0 positional, 0 keyword pair)
              6 POP_TOP
              7 LOAD_CONST               0 (None)
             10 RETURN_VALUE

Or maybe it's just an optimization that nobody has bothered with since 
the benefit is so trivial. But either way, all callables (sub-routines) 
in Python are functions, i.e. in principle they could, or should, return 
a result, even if in practice some of them don't. There is no callable 
type which lacks the ability to return a result.

Naturally they may not actually return a result if they never exit:

def this_is_a_function():
    while 1:
        pass
    return "You'll never see this!"

or if they exit via an exception:

def also_a_function():
    if 1:
        raise ValueError
    return "You'll never see this either!"

or if they just kill the running Python environment stone dead:

def still_a_function():
    import os
    os._exit(1)
    return "Have I beaten this dead horse enough?"


> But seriously, this is something that some functions do when they need
> to distinguish between returning something and not returning anything.
> Look at a dictionary's subscripting (which is effectively a function
> call):
> 
>>>> x={1:2}
>>>> x[1]
> 2
>>>> x[3]
> Traceback (most recent call last):
>   File "<pyshell#17>", line 1, in <module>
>     x[3]
> KeyError: 3

Yes, I'm aware that Python functions can raise exceptions :-)

 
> It can't return None to indicate "there was no such key in the
> dictionary", so it raises instead. There's only one way for a Python
> function to not have a return value: it has to not return.

Exactly my point. Functions return a value, and None is a value; 
procedures return, but not with a value. Python has the former, but not 
the later. Instead, we make do with the convention that something which 
is *intended* to be used as a procedure should return None to signal 
that, and the caller should just ignore the return result.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Thu Mar 13 21:59:05 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 14 Mar 2014 01:59:05 GMT
Subject: Deep vs. shallow copy?
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
 <87y50el1vf.fsf@elektro.pacujo.net>
 <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmpufKDDnWRBusutSR4hdxVu8LvmBp9SXjYJmBjy7rx+4Q@mail.gmail.com>
 <CALwzidkG1GdOH5PQDEzaj76aNW2OWCMXYkg4_xth38jtnvBJ9g@mail.gmail.com>
 <mailman.8137.1394756567.18130.python-list@python.org>
Message-ID: <53226269$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Fri, 14 Mar 2014 11:22:43 +1100, Chris Angelico wrote:

> Trollbridge: you have to pay a troll to cross.

Heh :-)

But seriously, there is a distinction to be made between returning from a 
sub-routine, and returning from a sub-routine with a return result. There 
may be alternative methods of exiting the sub-routine, e.g. a GOTO or 
COMEFROM that jumps outside of the function. Exceptions are a form of 
safe, limited GOTO: they can only jump out of a function, not into the 
middle of an arbitrary chunk of code, and they clean up the call stack 
when they jump. But these alternative methods are not what people 
consider *returning* from a sub-routine.

Unless they're trolling :-)




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rustompmody at gmail.com  Thu Mar 13 22:57:53 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 13 Mar 2014 19:57:53 -0700 (PDT)
Subject: Deep vs. shallow copy?
In-Reply-To: <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
 <87y50el1vf.fsf@elektro.pacujo.net>
 <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <738224f9-7e11-49c2-869e-381b3ca3103f@googlegroups.com>

On Friday, March 14, 2014 5:11:03 AM UTC+5:30, Steven D'Aprano wrote:
> On Thu, 13 Mar 2014 14:27:48 +0200, Marko Rauhamaa wrote:

> > Roy Smith :
> >>  Steven D'Aprano  wrote:
> >>> Because Python doesn't have true procedures
> >> What do you mean by "true procedure"? Are you just talking about
> >> subroutines that don't return any value, i.e. fortran's SUBROUTINE vs.
> >> FUNCTION?
> > Ah, the "no true procedure" argument:
> >  - No true procedure returns a value.
> >  - That's false. Python's procedures return None.

> Are you trolling again? 

> I'm sure that you know quite well that Python doesn't have a procedure 
> type. It uses a single keyword, def, for creating both functions and 
> functions-that-return-None.

> We should all agree that functions-that-return-None are used for the same 
> purpose as procedures, but they are still functions, and they have a 
> return result, namely None. If you don't believe me, believe Python:

> py> def func():
> ...     return 42
> ...
> py> def proc():
> ...     pass
> ...
> py> type(func)
> py> type(proc)
> py> repr(proc())
> 'None'

> In languages with procedures, that last line would be an error (either at 
> compile-time, or run-time) since a procedure wouldn't return anything to 
> use as argument to repr. But I'm sure that you know that.

> >  - They are not true procedures.

> Correct. They are functions that return None, rather than a subroutine 
> that doesn't have any return value at all. But I'm sure you know that.

I believe that you, Marko (and I) are saying exactly the same thing:

Wear language-lawyer hat: 
Python has no procedures -- just functions which may return None

Wear vanilla programmer hat:
The concept (Pascal) procedure is simulated by function-returning-None


From drsalists at gmail.com  Thu Mar 13 23:12:41 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Thu, 13 Mar 2014 20:12:41 -0700
Subject: Balanced trees
In-Reply-To: <532245fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <mailman.8013.1394471845.18130.python-list@python.org>
 <87zjkyq7nr.fsf@elektro.pacujo.net>
 <532245fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAGGBd_r2AjUT-wLrXVij21HrOEJYOU+XLQq6wsT6mT-CHbRx5g@mail.gmail.com>

On Thu, Mar 13, 2014 at 4:57 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Mon, 10 Mar 2014 19:34:48 +0200, Marko Rauhamaa wrote:
>
>>> With a high level language like Python, using the provided hash table
>>> will almost always cream any hand-built tree, no matter how
>>> advantageous the data is to the tree.
>>
>> The main thing is there are use cases where order is essential. That's
>> why I have had to implement the AVL tree in Python myself.
>
> from collections import OrderedDict
>
> gives you a fast, ordered mapping. In this case, the order is that of
> insertion order. If you want sort order instead, for "small" amounts of
> data, say below a million or ten million items, you're likely to have
> acceptable if not superior results by just sorting them items when and as
> needed.

This is one of my pet things.

Sorting the same (slightly tweaked) data inside of a tight loop is
rarely a good idea - despite the fact that the "sort" itself tends to
be O(n) with Python's rather awesome builtin sorting algorithm.  This
is because sorting inside a loop tends to yield O(n^2) algorithms, or
even O((n^2)*logn).

But if you're sorting once at the end of whatever other processing,
sorting is great.  It's (still) O(nlogn), but it's got a terrific
constant.


From steve+comp.lang.python at pearwood.info  Fri Mar 14 00:43:52 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 14 Mar 2014 04:43:52 GMT
Subject: Deep vs. shallow copy?
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
 <87y50el1vf.fsf@elektro.pacujo.net>
 <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <738224f9-7e11-49c2-869e-381b3ca3103f@googlegroups.com>
Message-ID: <53228908$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 13 Mar 2014 19:57:53 -0700, Rustom Mody wrote:

> I believe that you, Marko (and I) are saying exactly the same thing:

I believe that you and I are saying practically the same thing.


> Wear language-lawyer hat:
> Python has no procedures -- just functions which may return None

Almost. Functions (or methods) can return None as a regular value, e.g. 
the re.match and re.search functions return a MatchObject if there is a 
match, and None if there is not. Here, the fact the function returns None 
is nothing special -- it could have return 0, or -1, or "Surprise!" if 
the function author had wanted, the important thing is that you use it as 
a function. Normally you call the function for it's return result, even 
if that result happens to be None.

On the other hand, Python also has functions/methods which you call for 
their side-effects, not for their return result. In Pascal, Fortran and 
C, for example, the language provides a special type of subroutine that 
can only be called for it's side-effects. It is common to call these 
subroutines "procedures", and Python does not have them. We only have the 
convention that if a function is intended to be called for it's side-
effects (a procedure), it should return None.


> Wear vanilla programmer hat:
> The concept (Pascal) procedure is simulated by function-returning-None

Yes, agreed on this one.



-- 
Steven


From steve+comp.lang.python at pearwood.info  Fri Mar 14 01:02:21 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 14 Mar 2014 05:02:21 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <mailman.7937.1394311101.18130.python-list@python.org>
 <87eh2ctmht.fsf@elektro.pacujo.net>
 <mailman.7941.1394328694.18130.python-list@python.org>
 <87zjkz3eo3.fsf@elektro.pacujo.net>
 <mailman.7963.1394400019.18130.python-list@python.org>
 <87a9czrrax.fsf@elektro.pacujo.net>
 <531d3058$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87eh2atw6s.fsf@elektro.pacujo.net>
 <roy-BE3C76.09590110032014@news.panix.com>
 <mailman.8007.1394468681.18130.python-list@python.org>
 <8761nmrnfk.fsf@elektro.pacujo.net>
 <mailman.8013.1394471845.18130.python-list@python.org>
 <87zjkyq7nr.fsf@elektro.pacujo.net>
 <532245fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8142.1394766770.18130.python-list@python.org>
Message-ID: <53228d5d$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 13 Mar 2014 20:12:41 -0700, Dan Stromberg wrote:

> Sorting the same (slightly tweaked) data inside of a tight loop is
> rarely a good idea - despite the fact that the "sort" itself tends to be
> O(n) with Python's rather awesome builtin sorting algorithm.  This is
> because sorting inside a loop tends to yield O(n^2) algorithms, or even
> O((n^2)*logn).

I agree with you except for the word "rarely". It depends on how much 
data you have, and in my experience most people think that N = 100 is a 
lot :-)

Remember that Big Oh doesn't say anything about the constant of 
proportionality. If you have one function that behaves like O(N) but with 
a constant factor of 1000, and another function that behaves like 
O(N**2) with a constant factor of 0.001, the second, theoretically 
slower, function will actually be faster for N < one million.

So *in practice*, a solution that involves a theoretically worse Big Oh 
function but a significantly lower constant factor may turn out to be 
better for all the values you care about. Given the difference in speed 
between Python's built-ins, and the code you can write yourself in pure 
Python, it is normally better to push as much work as you can onto the 
built-ins.

And of course, we should not make assumptions as to what is faster and 
what is slower. After 15+ years, I'm still surprised about what ends up 
being faster in Python.


> But if you're sorting once at the end of whatever other processing,
> sorting is great.  It's (still) O(nlogn), but it's got a terrific
> constant.

Exactly!



-- 
Steven


From breamoreboy at yahoo.co.uk  Fri Mar 14 02:17:36 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Fri, 14 Mar 2014 06:17:36 +0000
Subject: Deep vs. shallow copy?
In-Reply-To: <CAPTjJmrFrbkziw35qDhMBBe3=7KsqK5HqxWXO-JWemQ_t3fZMQ@mail.gmail.com>
References: <53206e6a$0$2886$e4fe514c@news2.news.xs4all.nl>
 <mailman.8093.1394636439.18130.python-list@python.org>
 <53207d77$0$2886$e4fe514c@news2.news.xs4all.nl>
 <5320e8c9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-493F5F.07442713032014@news.panix.com>
 <87y50el1vf.fsf@elektro.pacujo.net>
 <5322420e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmpufKDDnWRBusutSR4hdxVu8LvmBp9SXjYJmBjy7rx+4Q@mail.gmail.com>
 <CALwzidkG1GdOH5PQDEzaj76aNW2OWCMXYkg4_xth38jtnvBJ9g@mail.gmail.com>
 <CAPTjJmrFrbkziw35qDhMBBe3=7KsqK5HqxWXO-JWemQ_t3fZMQ@mail.gmail.com>
Message-ID: <lfu6u0$cla$1@ger.gmane.org>

On 14/03/2014 00:22, Chris Angelico wrote:
>
> Trollbridge: you have to pay a troll to cross.
>

And you mustn't be afraid of the Black Night?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From dieter at handshake.de  Fri Mar 14 03:27:27 2014
From: dieter at handshake.de (dieter)
Date: Fri, 14 Mar 2014 08:27:27 +0100
Subject: pickle.dump (obj, conn)
References: <1394750199.11584.YahooMailNeo@web140104.mail.bf1.yahoo.com>
Message-ID: <87pplp6y00.fsf@handshake.de>

Pedro Izecksohn <izecksohn at yahoo.com> writes:

> ? Shouldn't pickle.dump (obj, conn) raise an Exception if conn is a TCP connection that was closed by the remote host?

It is quite difficult to detect the closing of a TCP channel in
a reliable way. At least, you should not trust that you are reliably
informed about it.

The behavior is related to output to TCP connections, not directly
to "pickle". 



From kent at lysator.liu.se  Fri Mar 14 10:10:07 2014
From: kent at lysator.liu.se (Kent =?utf-8?Q?Engstr=C3=B6m?=)
Date: Fri, 14 Mar 2014 15:10:07 +0100
Subject: script uses up all memory
References: <CACwCsY65gpn_Zx78wquE-rmrZu10pu9GYbzWd-Y3ypzHsMb2Yw@mail.gmail.com>
 <CACwCsY4nxs-4WmKboA9mOwrjQjXKXmaBPTuuq0GSmjzEpA3efQ@mail.gmail.com>
Message-ID: <m3bnx8ub0g.fsf@lysator.liu.se>

Larry Martell <larry.martell at gmail.com> writes:
> I figured out what is causing this. Each pass through the loop it does:
>
> self.tools = Tool.objects.filter(ip__isnull=False)
>
> And that is what is causing the memory consumption. If I move that
> outside the loop and just do that once the memory issue goes away. Now
> I need to figure out why this is happening and how to prevent it as
> they do want to query the db each pass through the loop in case it has
> been updated.

Django saves a copy of every executed SQL query if it is in debug mode
(if the DEBUG setting is true). See

https://docs.djangoproject.com/en/dev/faq/models/#why-is-django-leaking-memory

Regards,
/ Kent Engstr?m, Lysator



From invalid at invalid.invalid  Fri Mar 14 14:53:57 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Fri, 14 Mar 2014 18:53:57 +0000 (UTC)
Subject: imapclient Gmail search() times
Message-ID: <lfvj84$1n4$1@reader1.panix.com>

I'm working on a small app to help sort/organize my mail via Gmail's
IMAP server, and I'm using imapclient (BTW it's a _huge_ improvement
over imaplib).

The odd thing I'm seeing is that when searching a large "folder" (All
Mail), I get wildly different times depending on what header I search.

  allmail = IMAPClient(HOST, use_uid=True, ssl=True, port=993)
  allmail.login(USERNAME, PASSWORD)
  allmail.select_folder('[Gmail]/All Mail')

Searching on "Message-Id:" is fast (sub-second):

  irt = allmail.search('HEADER Message-ID %s' % msgid)

Searching on "In-Reply-To:" takes 10-15 seconds:

  rt  = allmail.search('HEADER In-Reply-To %s' % msgid)

[IIRC, I've got about 22000 messages in the 'All Mail' "folder".]

I'm assuming this is just due to the way that Google implmented their
IMAP server code, but I thought I'd ask if anybody else had noticed
this.  Perhaps I'm doing something stupid, but I can't imagine what it
would be....
  
-- 
Grant Edwards               grant.b.edwards        Yow! I have a TINY BOWL in
                                  at               my HEAD
                              gmail.com            


From pmawhorter at gmail.com  Fri Mar 14 14:51:14 2014
From: pmawhorter at gmail.com (Peter Mawhorter)
Date: Fri, 14 Mar 2014 11:51:14 -0700
Subject: PEP/GSoC idea: built-in parser generator module for Python?
Message-ID: <CABaZ=CGbOw7ymp1Uis7ACYCMW9U1iuXuYnEfi2Rc_W-zTZ1rAA@mail.gmail.com>

First of all, hi everyone, I'm new to this list.

I'm a grad student who's worked on and off with Python on various
projects for 8ish years now. I recently wanted to construct a parser
for another programing language in Python and was dissapointed that
Python doesn't have a built-in module for building parsers, which
seems like a common-enough task. There are plenty of different
3rd-party parsing libraries available, specialized in lots of
different ways (see e.g., [1]). I happened to pick one that seemed
suitable for my needs but didn't turn out to support the recursive
structures that I needed to parse. Rather than pick a different one I
just built my own parser generator module, and used that to build my
parser: problem solved.

It would have been much nicer if there were a fully-featured builtin
parser generator module in Python, however, and the purpose of this
email is to test the waters a bit: is this something that other people
in the Python community would be interested in? I imagine the route to
providing a built-in parser generator module would be to first canvass
the community to figure out what third-party libraries they use, and
then contact the developers of some of the top libraries to see if
they'd be happy integrating as a built-in module. At that point
someone would need to work to integrate the chosen third-party library
as a built-in module (ideally with its developers).

>From what I've looked at PyParsing and PLY seem to be standout parser
generators for Python, PyParsing has a bit more Pythonic syntax from
what I've seen. One important issue would be speed though: an
implementation mostly written in C for low-level parsing tasks would
probably be much preferrable to one written in pure Python, since a
builtin module should be geared towards efficiency, but I don't
actually know exactly how that would work (I've both extended and
embedded Python with/in C before, but I'm not sure how that kind of
project relates to writing a built-in module in C).

Sorry if this is a bit rambly, but I'm interested in feedback from the
community on this idea: is a builtin parser generator module
desirable? If so, would integrating PyParsing as a builtin module be a
good solution? What 3rd-party parsing module do you think would serve
best for this purpose?

-Peter Mawhorter

[1] http://nedbatchelder.com/text/python-parsers.html


From tjreedy at udel.edu  Fri Mar 14 15:48:23 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Fri, 14 Mar 2014 15:48:23 -0400
Subject: PEP/GSoC idea: built-in parser generator module for Python?
In-Reply-To: <CABaZ=CGbOw7ymp1Uis7ACYCMW9U1iuXuYnEfi2Rc_W-zTZ1rAA@mail.gmail.com>
References: <CABaZ=CGbOw7ymp1Uis7ACYCMW9U1iuXuYnEfi2Rc_W-zTZ1rAA@mail.gmail.com>
Message-ID: <lfvmee$gng$1@ger.gmane.org>

On 3/14/2014 2:51 PM, Peter Mawhorter wrote:
> First of all, hi everyone, I'm new to this list.

Welcome.

> I'm a grad student who's worked on and off with Python on various
> projects for 8ish years now. I recently wanted to construct a parser
> for another programing language in Python and was dissapointed that
> Python doesn't have a built-in module for building parsers, which
> seems like a common-enough task. There are plenty of different
> 3rd-party parsing libraries available, specialized in lots of
> different ways (see e.g., [1]). I happened to pick one that seemed
> suitable for my needs but didn't turn out to support the recursive
> structures that I needed to parse. Rather than pick a different one I
> just built my own parser generator module, and used that to build my
> parser: problem solved.
>
> It would have been much nicer if there were a fully-featured builtin
> parser generator module in Python, however, and the purpose of this
> email is to test the waters a bit: is this something that other people
> in the Python community would be interested in? I imagine the route to
> providing a built-in parser generator module would be to first canvass
> the community to figure out what third-party libraries they use, and
> then contact the developers of some of the top libraries to see if
> they'd be happy integrating as a built-in module. At that point
> someone would need to work to integrate the chosen third-party library
> as a built-in module (ideally with its developers).

I think the idea has been raised before, but I am not sure which list 
(this one, pydev, or python-ideas).

My first reaction, as a core developer, is that the stdlib is, if 
anything, too large. It is already not as well-maintained as we would like.

My second is that parser generation is an application, not a library. A 
parser generator is used by running it with an input specification, not 
by importing it and using specific functions and classes.

>  From what I've looked at PyParsing and PLY seem to be standout parser
> generators for Python, PyParsing has a bit more Pythonic syntax from
> what I've seen. One important issue would be speed though: an
> implementation mostly written in C for low-level parsing tasks would
> probably be much preferrable to one written in pure Python, since a
> builtin module should be geared towards efficiency, but I don't
> actually know exactly how that would work (I've both extended and
> embedded Python with/in C before, but I'm not sure how that kind of
> project relates to writing a built-in module in C).

Something written in Python can be run with any implementation of 
Python. Something written in C tends to be tied to CPython,


> Sorry if this is a bit rambly, but I'm interested in feedback from the
> community on this idea: is a builtin parser generator module
> desirable? If so, would integrating PyParsing as a builtin module be a
> good solution? What 3rd-party parsing module do you think would serve
> best for this purpose?

> [1] http://nedbatchelder.com/text/python-parsers.html

Perhaps something like this should be in the wiki, if not already.

-- 
Terry Jan Reedy



From thraxodon at bitch.invalid  Fri Mar 14 20:21:33 2014
From: thraxodon at bitch.invalid (THRAXODON)
Date: Fri, 14 Mar 2014 20:21:33 -0400
Subject: JESUS EXPLAINED TO ME THAT HUMANS HAVE ORIGINS IN THE DEVONIAN.
Message-ID: <lg06ec$p1r$2@speranza.aioe.org>

==================
 >BREAKING HOGWASH!
==================
 >
TALK.ORIGINS RECENTLY ANNOUNCED THAT HUMANS HAVE ORIGINS IN THE DEVONIAN.
 >
THIS RECENT RECOGNITION OF THE GREATEST FACT IN EARTH'S HISTORY IS 
PROFOUND TO http://www.talkorigins.org/ CREDIBILITY. (Also see 
http://www.ediacara.org/)
 >
DAVID IAIN GREIG, TALK.ORIGINS DICTATOR WAS RELUCTANT BUT FINALLY 
ANNOUNCED IN A PAPER IN http://www.sciencemag.org/ THAT THRINAXODON WAS 
RIGHT, AND HUMANS DO HAVE ORIGINS IN THE DEVONIAN!
 >
===========================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/6f501c469c7af24f#

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/3aad75c16afb0b82#

====================================

http://thrinaxodon.wordpress.com/

===================================

THRINAXODON ONLY HAD THIS TO SAY:

"I..I...I...Can't believe it. This completely disproved Darwinian
orthodoxy."

===================================

THE BASTARDS AT THE SMITHSONIAN, AND THE LEAKEY FOUNDATION ARE ERODING
WITH FEAR.

===========================
THESE ASSHOLES ARE GOING TO DIE:
THOMAS AQUINAS;
ALDOUS HUXLEY;
BOB CASANVOVA;
SkyEyes;
DAVID IAIN GRIEG;
MARK ISAAK;
JOHN HARSHAM;
RICHARD NORMAN;
DR. DOOLITTLE;
CHARLES DARWIN;
MARK HORTON;
ERIK SIMPSON;
HYPATIAB7;
PAUL J. GANS;
JILLERY;
WIKI TRIK;
THRINAXODON;
PETER NYIKOS;
RON OKIMOTO;
JOHN S. WILKINS
===========================

THRINAXODON WAS SCOURING ANOTHER DEVONIAN FOSSIL BED, AND FOUND A
HUMAN SKULL, AND A HUMAN FEMUR. HE ANALYSED THE FINDS, AND SAW THAT
THEY WERE NOT NORMAL ROCKS. THESE WERE FOSSILIZED BONES. THEY EVEN HAD
TOOTH MARKS ON THEM. SO, THRINAXODON BROUGHT THEM TO THE LEAKEY
FOUNDATION, THEY UTTERLY DISMISSED IT, AND SAID, "We want to keep
people thinking that humans evolved 2 Ma." THRINAXODON BROUGHT HIS
SWORD, AND SAID, "SCIENCE CORRECTS ITSELF." RICHARD LEAKEY SAID, "That
is a myth, for people to believe in science." THRINAXODON PLANS TO
BRING DOOM TO SCIENCE, ITSELF.

============================

THRINAXODON IS NOW ON REDDIT
-- 
---Thrinaxodon


From joshua at landau.ws  Fri Mar 14 21:13:13 2014
From: joshua at landau.ws (Joshua Landau)
Date: Sat, 15 Mar 2014 01:13:13 +0000
Subject: Balanced trees
In-Reply-To: <lffv32$mqo$1@ger.gmane.org>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
Message-ID: <CAN1F8qU=2K6ysbpnu-JoUtfWfTToRsOaRek0dSQzjPx_sYzPKQ@mail.gmail.com>

On 8 March 2014 20:37, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> I've found this link useful http://kmike.ru/python-data-structures/
>
> I also don't want all sorts of data structures added to the Python library.
> I believe that there are advantages to leaving specialist data structures on
> pypi or other sites, plus it means Python in a Nutshell can still fit in
> your pocket and not a 40 ton articulated lorry, unlike the Java equivalent.

The thing we really need is for the blist containers to become stdlib
(but not to replace the current list implementation). The rejected PEP
(http://legacy.python.org/dev/peps/pep-3128/) misses a few important
points, largely in how the "log(n)" has a really large base:
random.choice went from 1.2?s to 1.6?s from n=1 to n=10?, vs 1.2?s for
a standard list.

Further, it's worth considering a few advantages:

* copy is O(1), allowing code to avoid mutation by just copying its
input, which is good practice.

* FIFO is effectively O(1), as the time just about doubles from n=1 to
n=10? so will never actually branch that much. There is still a speed
benefit of collections.deque, but it's much, much less significant.
This is very useful when considering usage as a multi-purpose data
structure, and removes demand for explicit linked lists (which have
foolishly been reimplemented loads of times).

* It reduces demand for trees:
    * There are efficient implementations of sortedlist, sortedset and
sorteddict.
    * Slicing, slice assignment and slice deletion are really fast.
    * Addition of lists is sublinear. Instead of
"list(itertools.chain(...))", one can add in a loop and end up
*faster*.

I think blist isn't very popular not because it isn't really good, but
because it isn't a specialised structure. It is, however, almost there
for almost every circumstance. This can help keep the standard library
clean, especially of tree data structures.

Here's what we kill:

* Linked lists and doubly-linked lists, which are scarily popular for
whatever reason. Sometimes people claim that collections.deque isn't
powerful enough for whatever they want, and blist will almost
definitely sate those cases.

* Balanced trees, with blist.sortedlist. This is actually needed right now.

* Poor performance in the cases where a lot of list merging and pruning happens.

* Most uses of bisect.

* Some instances where two data structures are used in parallel in
order to keep performance fast on disparate operations (like `x in y`
and `y[i]`).

Now, I understand there are downsides to blist. Particularly, I've
looked through the "benchmarks" and they seem untruthful. Further,
we'd need a maintainer. Finally, nobody jumps at blists because
they're rarely the obvious solution. Rather, they attempt to be a
different general solution. Hopefully, though, a stdlib inclusion
could make them a lot more obvious, and support in some current
libraries could make them feel more at home.

I don't know whether this is a good idea, but I do feel that it is
more promising and general than having a graph in the standard
library.


From horse.shit at bitch.invalid  Sat Mar 15 07:46:20 2014
From: horse.shit at bitch.invalid (HORSE SHIT)
Date: Sat, 15 Mar 2014 07:46:20 -0400
Subject: OH MY GOD! HUMANS HAVE ORIGINS IN THE DEVONIAN!
Message-ID: <lg1ei7$cvn$1@speranza.aioe.org>

==================
 >BREAKING HOGWASH!
==================
 >
TALK.ORIGINS RECENTLY ANNOUNCED THAT HUMANS HAVE ORIGINS IN THE DEVONIAN.
 >
THIS RECENT RECOGNITION OF THE GREATEST FACT IN EARTH'S HISTORY IS 
PROFOUND TO http://www.talkorigins.org/ CREDIBILITY. (Also see 
http://www.ediacara.org/)
 >
DAVID IAIN GREIG, TALK.ORIGINS DICTATOR WAS RELUCTANT BUT FINALLY 
ANNOUNCED IN A PAPER IN http://www.sciencemag.org/ THAT THRINAXODON WAS 
RIGHT, AND HUMANS DO HAVE ORIGINS IN THE DEVONIAN!
 >
===========================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/6f501c469c7af24f#

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/3aad75c16afb0b82#

====================================

http://thrinaxodon.wordpress.com/

===================================

THRINAXODON ONLY HAD THIS TO SAY:

"I..I...I...Can't believe it. This completely disproved Darwinian
orthodoxy."

===================================

THE BASTARDS AT THE SMITHSONIAN, AND THE LEAKEY FOUNDATION ARE ERODING
WITH FEAR.

===========================
THESE ASSHOLES ARE GOING TO DIE:
THOMAS AQUINAS;
ALDOUS HUXLEY;
BOB CASANVOVA;
SkyEyes;
DAVID IAIN GRIEG;
MARK ISAAK;
JOHN HARSHAM;
RICHARD NORMAN;
DR. DOOLITTLE;
CHARLES DARWIN;
MARK HORTON;
ERIK SIMPSON;
HYPATIAB7;
PAUL J. GANS;
JILLERY;
WIKI TRIK;
THRINAXODON;
PETER NYIKOS;
RON OKIMOTO;
JOHN S. WILKINS
===========================

THRINAXODON WAS SCOURING ANOTHER DEVONIAN FOSSIL BED, AND FOUND A
HUMAN SKULL, AND A HUMAN FEMUR. HE ANALYSED THE FINDS, AND SAW THAT
THEY WERE NOT NORMAL ROCKS. THESE WERE FOSSILIZED BONES. THEY EVEN HAD
TOOTH MARKS ON THEM. SO, THRINAXODON BROUGHT THEM TO THE LEAKEY
FOUNDATION, THEY UTTERLY DISMISSED IT, AND SAID, "We want to keep
people thinking that humans evolved 2 Ma." THRINAXODON BROUGHT HIS
SWORD, AND SAID, "SCIENCE CORRECTS ITSELF." RICHARD LEAKEY SAID, "That
is a myth, for people to believe in science." THRINAXODON PLANS TO
BRING DOOM TO SCIENCE, ITSELF.

============================

THRINAXODON IS NOW ON REDDIT
-- 
---Thrinaxodon


From breamoreboy at yahoo.co.uk  Sat Mar 15 08:31:26 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 15 Mar 2014 12:31:26 +0000
Subject: blist in standard library  (was Re: Balanced trees)
In-Reply-To: <CAN1F8qU=2K6ysbpnu-JoUtfWfTToRsOaRek0dSQzjPx_sYzPKQ@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <CAN1F8qU=2K6ysbpnu-JoUtfWfTToRsOaRek0dSQzjPx_sYzPKQ@mail.gmail.com>
Message-ID: <lg1h71$rtb$1@ger.gmane.org>

On 15/03/2014 01:13, Joshua Landau wrote:
> On 8 March 2014 20:37, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>> I've found this link useful http://kmike.ru/python-data-structures/
>>
>> I also don't want all sorts of data structures added to the Python library.
>> I believe that there are advantages to leaving specialist data structures on
>> pypi or other sites, plus it means Python in a Nutshell can still fit in
>> your pocket and not a 40 ton articulated lorry, unlike the Java equivalent.
>
> The thing we really need is for the blist containers to become stdlib
> (but not to replace the current list implementation). The rejected PEP
> (http://legacy.python.org/dev/peps/pep-3128/) misses a few important
> points, largely in how the "log(n)" has a really large base:
> random.choice went from 1.2?s to 1.6?s from n=1 to n=10?, vs 1.2?s for
> a standard list.
>
> Further, it's worth considering a few advantages:
>
> * copy is O(1), allowing code to avoid mutation by just copying its
> input, which is good practice.
>
> * FIFO is effectively O(1), as the time just about doubles from n=1 to
> n=10? so will never actually branch that much. There is still a speed
> benefit of collections.deque, but it's much, much less significant.
> This is very useful when considering usage as a multi-purpose data
> structure, and removes demand for explicit linked lists (which have
> foolishly been reimplemented loads of times).
>
> * It reduces demand for trees:
>      * There are efficient implementations of sortedlist, sortedset and
> sorteddict.
>      * Slicing, slice assignment and slice deletion are really fast.
>      * Addition of lists is sublinear. Instead of
> "list(itertools.chain(...))", one can add in a loop and end up
> *faster*.
>
> I think blist isn't very popular not because it isn't really good, but
> because it isn't a specialised structure. It is, however, almost there
> for almost every circumstance. This can help keep the standard library
> clean, especially of tree data structures.
>
> Here's what we kill:
>
> * Linked lists and doubly-linked lists, which are scarily popular for
> whatever reason. Sometimes people claim that collections.deque isn't
> powerful enough for whatever they want, and blist will almost
> definitely sate those cases.
>
> * Balanced trees, with blist.sortedlist. This is actually needed right now.
>
> * Poor performance in the cases where a lot of list merging and pruning happens.
>
> * Most uses of bisect.
>
> * Some instances where two data structures are used in parallel in
> order to keep performance fast on disparate operations (like `x in y`
> and `y[i]`).
>
> Now, I understand there are downsides to blist. Particularly, I've
> looked through the "benchmarks" and they seem untruthful. Further,
> we'd need a maintainer. Finally, nobody jumps at blists because
> they're rarely the obvious solution. Rather, they attempt to be a
> different general solution. Hopefully, though, a stdlib inclusion
> could make them a lot more obvious, and support in some current
> libraries could make them feel more at home.
>
> I don't know whether this is a good idea, but I do feel that it is
> more promising and general than having a graph in the standard
> library.
>

I'd raise this on python-dev or python ideas as a result of reading PEP 
3128.  Specifically the second paragraph states Raymond Hettinger's sage 
advice:-

"Depending on its success as a third-party module, it still has a chance 
for inclusion in the collections module. The essential criteria for that 
is whether it is a superior choice for some real-world use cases. I've 
scanned my own code and found no instances where BList would have been 
preferable to a regular list. However, that scan has a selection bias 
because it doesn't reflect what I would have written had BList been 
available. So, after a few months, I intend to poll comp.lang.python for 
BList success stories. If they exist, then I have no problem with 
inclusion in the collections module. After all, its learning curve is 
near zero -- the only cost is the clutter factor stemming from 
indecision about the most appropriate data structure for a given task."

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From jnkoushik at gmail.com  Sat Mar 15 12:26:21 2014
From: jnkoushik at gmail.com (Jayanth Koushik)
Date: Sat, 15 Mar 2014 09:26:21 -0700 (PDT)
Subject: 'complex' function with string argument.
Message-ID: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>

Hi everyone!

This is regarding the inbuilt 'complex' function. The python docs say:
"Note: When converting from a string, the string must not contain whitespace around the central + or - operator. For example, complex('1+2j') is fine, but complex('1 + 2j') raises ValueError."

Why is this so? Why can't spaces be allowed everywhere and simply ignored? I went through the source and it did not seem like this was an internal requirement, so it seems like a design choice. Is there any reason why spaces in the middle would be a problem?

Jayanth Koushik


From albert at spenarnc.xs4all.nl  Sat Mar 15 13:24:00 2014
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 15 Mar 2014 17:24:00 GMT
Subject: intersection, union, difference, symmetric difference for
 dictionaries
References: <G57Pu.24239$Th2.4990@tornado.fastwebnet.it>
Message-ID: <53248cb0$0$25075$e4fe514c@dreader37.news.xs4all.nl>

In article <G57Pu.24239$Th2.4990 at tornado.fastwebnet.it>,
mauro  <mauro at gmail.com> wrote:
> Dictionaries and sets share a few properties:
>- Dictionaries keys are unique as well as sets items
>- Dictionaries and sets are both unordered
>- Dictionaries and sets are both accessed by key
>- Dictionaries and sets are both mutables
>
>So I wonder why operations such us intersection, union, difference,
>symmetric difference that are available for sets and are not available
>for dictionaries without going via key dictviews.

This is a plain bad idea.
Dictionaries correspond to the mathematical concept of a mapping.
A mapping (or a function) is a set in math, as everything is a set.
It is a subset of the product set of two set A and B where
there is exactly one pair for each a in A.

No sane mathematician talks about unions, intersections etc.
of those sets, though clearly they are well defined.
OTOH there is a very rich vocabulary specific for the properties
of functions.

So dear mauro do as everybody does, as soon as you've invented
something useful related to dicts, you'll discover that it correspond
to an age old mathematical concept. It is unwise not to borrow its
name.

Those old geezers, Chebychov, Euler, Laplace, Fourier had their
marbles in a row. It is hard to outsmart them.

Groetjes Albert
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From harrismh777 at gmail.com  Sat Mar 15 17:24:37 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 15 Mar 2014 16:24:37 -0500
Subject: test
Message-ID: <lg2geg$48n$1@speranza.aioe.org>

test


From harrismh777 at gmail.com  Sat Mar 15 17:38:18 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 15 Mar 2014 16:38:18 -0500
Subject: Sharing: File Reader Generator  with & w/o Policy
Message-ID: <lg2h87$6fj$1@speranza.aioe.org>

hi folks, I am posting to share a File Reader Generator which I have
been playing with, that simplifies reading of text files on-demand:
like log files, config files, small record flat data-bases, &c.

I have two generators to share, one with & one without "policy".
The idea is to have the generator open and close the file (with error
checking:  try-finish block) and then maintain its state for on-demand
reading either into memory (as list or dict) or for in-line processing.

I will demonstrate the generators here, and then post the code 
following. The generator will be reading a path+filename of a local disk 
file and printing it as in this simple case without policy:
 >>> from my_utils import *

 >>> for record in fName(path+"my_fox"):
	      print(record)

The quick brown fox jumped
over the lazy dog's tail.

Now is the time for all
good women to come to the
aid of computer science!
 >>>

The second generator adds "policy" to the generator processing and
yields tuples, rather than strings. Each tuple contains the record 
number (from zero), and record length (minus the line end), and the 
record itself (stripped of the line end):
 >>>
 >>> for record in fnName(path+"my_fox"):
	      print(record)

(0, 26, 'The quick brown fox jumped')
(1, 25, "over the lazy dog's tail.")
(2, 0, '')
(3, 23, 'Now is the time for all')
(4, 25, 'good women to come to the')
(5, 24, 'aid of computer science!')
 >>>
 >>>

I will now share the source by allowing the fName(filename) utility
to expose itself.  Enjoy:
 >>>
 >>> for record in fName(path+"my_utils.py"):
	      print(record)

#---------------------------------------------------------
# fName(filename)   generator: file reader iterable
#---------------------------------------------------------
def fName(filename):
     try:
         fh = open(filename, 'r')
     except FileNotFoundError as err_code:
         print (err_code)
     else:
         while True:
             linein = fh.readline()
             if (linein!=''):
                 yield(linein.strip('\n'))
             else:
                 break
         fh.close()
     finally:
         None

#---------------------------------------------------------
# fnName(filename)   generator: file reader iterable
#---------------------------------------------------------
def fnName(filename):
     try:
         fh = open(filename, 'r')
     except FileNotFoundError as err_code:
         print (err_code)
     else:
         line_count = 0
         while True:
             linein = fh.readline()
             if (linein!=''):
                 lineout = linein.strip('\n')
                 length = len(lineout)
                 yield((line_count, length, lineout))
                 line_count+=1
             else:
                 break
         fh.close()
     finally:
         None

#---------------------------------------------------------
# {next util}
#---------------------------------------------------------
 >>>

mark h harris


From python at mrabarnett.plus.com  Sat Mar 15 17:56:27 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Sat, 15 Mar 2014 21:56:27 +0000
Subject: Sharing: File Reader Generator  with & w/o Policy
In-Reply-To: <lg2h87$6fj$1@speranza.aioe.org>
References: <lg2h87$6fj$1@speranza.aioe.org>
Message-ID: <5324CC8B.6000206@mrabarnett.plus.com>

On 2014-03-15 21:38, Mark H Harris wrote:
> hi folks, I am posting to share a File Reader Generator which I have
> been playing with, that simplifies reading of text files on-demand:
> like log files, config files, small record flat data-bases, &c.
>
> I have two generators to share, one with & one without "policy".
> The idea is to have the generator open and close the file (with error
> checking:  try-finish block) and then maintain its state for on-demand
> reading either into memory (as list or dict) or for in-line processing.
>
> I will demonstrate the generators here, and then post the code
> following. The generator will be reading a path+filename of a local disk
> file and printing it as in this simple case without policy:
>   >>> from my_utils import *
>
>   >>> for record in fName(path+"my_fox"):
> 	      print(record)
>
> The quick brown fox jumped
> over the lazy dog's tail.
>
> Now is the time for all
> good women to come to the
> aid of computer science!
>   >>>
>
> The second generator adds "policy" to the generator processing and
> yields tuples, rather than strings. Each tuple contains the record
> number (from zero), and record length (minus the line end), and the
> record itself (stripped of the line end):
>   >>>
>   >>> for record in fnName(path+"my_fox"):
> 	      print(record)
>
> (0, 26, 'The quick brown fox jumped')
> (1, 25, "over the lazy dog's tail.")
> (2, 0, '')
> (3, 23, 'Now is the time for all')
> (4, 25, 'good women to come to the')
> (5, 24, 'aid of computer science!')
>   >>>
>   >>>
>
> I will now share the source by allowing the fName(filename) utility
> to expose itself.  Enjoy:
>   >>>
>   >>> for record in fName(path+"my_utils.py"):
> 	      print(record)
>
> #---------------------------------------------------------
> # fName(filename)   generator: file reader iterable
> #---------------------------------------------------------
> def fName(filename):
>       try:
>           fh = open(filename, 'r')
>       except FileNotFoundError as err_code:
>           print (err_code)
>       else:
>           while True:
>               linein = fh.readline()
>               if (linein!=''):
>                   yield(linein.strip('\n'))
>               else:
>                   break
>           fh.close()
>       finally:
>           None
>
I don't like how it always swallows the exception, so you can't tell
whether the file doesn't exist or exists but is empty, and no way to
specify the file's encoding.

Why do you have the 'finally' clause with 'None' in it? Instead of None
you should have 'pass', or, better yet, omit the clause entirely.

You can also shorten it somewhat:

def fName(filename):
     try:
         with open(filename, 'r') as fh:
             for linein in fh:
                 yield linein.strip('\n')
     except FileNotFoundError as err_code:
         print(err_code)

[snip]



From harrismh777 at gmail.com  Sat Mar 15 20:36:21 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 15 Mar 2014 19:36:21 -0500
Subject: Sharing: File Reader Generator  with & w/o Policy
References: <lg2h87$6fj$1@speranza.aioe.org>
 <mailman.8156.1394920773.18130.python-list@python.org>
Message-ID: <lg2rm6$t3p$1@speranza.aioe.org>

On 3/15/14 4:56 PM, MRAB wrote:

> I don't like how it always swallows the exception, so you can't tell
> whether the file doesn't exist or exists but is empty, and no way to
> specify the file's encoding.

Yes, the error handling needs more robustness/ and instead of printing
the errcode, my actual model on system will log it.
>
> Why do you have the 'finally' clause with 'None' in it? Instead of None
> you should have 'pass', or, better yet, omit the clause entirely.

Its a stub-in really, and that's all at this point.  The 'finally' 
happens regardless of whether the exception occurs, and I don't need
anything there yet, just don't want to forget it.

I've been playing around with wrapping generators within generators for 
readability and simplicity. Like this, where I'm going to wrap the 
fnName(filename) generator within a getnumline(filename) wrapper:

 >>> from my_utils import *

 >>> def getnumline(filename):
	      for record in fnName(filename):
		      yield(record)

 >>> line = getnumline("my_foxy")
 >>>
 >>> next(line)
(0, 26, 'The quick brown fox jumped')
 >>>
 >>> next(line)
(1, 25, "over the lazy dog's tail.")
 >>>

Or this, where I put it all in memory as a dict:

 >>> d1={}
 >>> for line in getnumline("my_foxy"):
	d1[line[0]]=(line[1], line[2])

 >>> for key in d1:
	print (d1[key])

(26, 'The quick brown fox jumped')
(25, "over the lazy dog's tail.")
(0, '')
(23, 'Now is the time for all')
(25, 'good women to come to the')
(24, 'aid of computer science!')
 >>>

marcus



From harrismh777 at gmail.com  Sat Mar 15 20:45:57 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 15 Mar 2014 19:45:57 -0500
Subject: Sharing: File Reader Generator  with & w/o Policy
References: <lg2h87$6fj$1@speranza.aioe.org>
 <mailman.8156.1394920773.18130.python-list@python.org>
Message-ID: <lg2s85$u7q$1@speranza.aioe.org>

On 3/15/14 4:56 PM, MRAB wrote:
>
> def fName(filename):
>     try:
>         with open(filename, 'r') as fh:
>             for linein in fh:
>                 yield linein.strip('\n')
>     except FileNotFoundError as err_code:
>         print(err_code)
>
> [snip]
>

The "with" confuses me because I am not sure specifically what happens 
in the context manager. I'm taking it for granted in this case that 
__exit__() closes the file?

I am finding many examples of file handling using the context manager, 
but none so far that wrap into a generator; more often and file object. 
Is there a preference for file object over generator?

marcus


From harrismh777 at gmail.com  Sat Mar 15 21:06:15 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 15 Mar 2014 20:06:15 -0500
Subject: Sharing: File Reader Generator  with & w/o Policy
References: <lg2h87$6fj$1@speranza.aioe.org>
 <mailman.8156.1394920773.18130.python-list@python.org>
Message-ID: <lg2te7$oq$1@speranza.aioe.org>

On 3/15/14 4:56 PM, MRAB wrote:

>
> You can also shorten it somewhat:

Thanks, I like it... I shortened the fnName() also:

#---------------------------------------------------------
# fn2Name(filename)   generator: file reader iterable
#---------------------------------------------------------
def fn2Name(filename):
     try:
         with open(filename, 'r') as fh:    <=========== can you tell me
             line_count = 0
             for linein in fh:
                 lineout = linein.strip('\n')
                 length = len(lineout)
                 yield((line_count, length, lineout))
                 line_count+=1
     except FileNotFoundError as err_code:
         print(err_code)

#---------------------------------------------------------


...  where I can go to find out (for specific contexts) what the 
__init__() and __exit__() are actually doing, like for instance in this 
case does the filename get closed in __exit__(), and also if errors 
occur does the file close automatically?  thanks

marcus


From breamoreboy at yahoo.co.uk  Sat Mar 15 21:32:10 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 16 Mar 2014 01:32:10 +0000
Subject: Sharing: File Reader Generator  with & w/o Policy
In-Reply-To: <lg2te7$oq$1@speranza.aioe.org>
References: <lg2h87$6fj$1@speranza.aioe.org>
 <mailman.8156.1394920773.18130.python-list@python.org>
 <lg2te7$oq$1@speranza.aioe.org>
Message-ID: <lg2uuc$j3r$1@ger.gmane.org>

On 16/03/2014 01:06, Mark H Harris wrote:
> On 3/15/14 4:56 PM, MRAB wrote:
>
>>
>> You can also shorten it somewhat:
>
> Thanks, I like it... I shortened the fnName() also:
>
> #---------------------------------------------------------
> # fn2Name(filename)   generator: file reader iterable
> #---------------------------------------------------------
> def fn2Name(filename):
>      try:
>          with open(filename, 'r') as fh:    <=========== can you tell me
>              line_count = 0
>              for linein in fh:
>                  lineout = linein.strip('\n')
>                  length = len(lineout)
>                  yield((line_count, length, lineout))
>                  line_count+=1
>      except FileNotFoundError as err_code:
>          print(err_code)
>
> #---------------------------------------------------------
>
>
> ...  where I can go to find out (for specific contexts) what the
> __init__() and __exit__() are actually doing, like for instance in this
> case does the filename get closed in __exit__(), and also if errors
> occur does the file close automatically?  thanks
>
> marcus

Start here 
http://docs.python.org/3/library/stdtypes.html#context-manager-types

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From travisgriggs at gmail.com  Sat Mar 15 21:48:38 2014
From: travisgriggs at gmail.com (Travis Griggs)
Date: Sat, 15 Mar 2014 18:48:38 -0700
Subject: test
In-Reply-To: <lg2geg$48n$1@speranza.aioe.org>
References: <lg2geg$48n$1@speranza.aioe.org>
Message-ID: <EEA58C91-70EF-4A00-A333-941B429E9ADC@gmail.com>



> On Mar 15, 2014, at 14:24, Mark H Harris <harrismh777 at gmail.com> wrote:
> 
> test

Pass


From steve+comp.lang.python at pearwood.info  Sat Mar 15 22:01:21 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 16 Mar 2014 02:01:21 GMT
Subject: Sharing: File Reader Generator  with & w/o Policy
References: <lg2h87$6fj$1@speranza.aioe.org>
Message-ID: <532505f0$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sat, 15 Mar 2014 16:38:18 -0500, Mark H Harris wrote:

> hi folks, I am posting to share a File Reader Generator which I have
> been playing with, that simplifies reading of text files on-demand: like
> log files, config files, small record flat data-bases, &c.

Reading from files is already pretty simple. I would expect that it will 
be harder to learn the specific details of custom, specialised, file 
readers that *almost*, but not quite, do what you want, than to just 
write a couple of lines of code to do what you need when you need it. 
Particularly for interactive use, where robustness is less important than 
ease of use.


> I have two generators to share, one with & one without "policy". 

What's "policy"?


> The idea is to have the generator open and close the file (with error
> checking:  try-finish block) and then maintain its state for on-demand
> reading either into memory (as list or dict) or for in-line processing.
> 
> I will demonstrate the generators here, and then post the code
> following. The generator will be reading a path+filename of a local disk
> file and printing it as in this simple case without policy:
>
> >>> from my_utils import *
> >>> for record in fName(path+"my_fox"):
> 	      print(record)
> 
> The quick brown fox jumped
> over the lazy dog's tail.

What's "fName" mean? "File name"? That's a horribly misleading name, 
since it *takes* a file name as argument, it doesn't return one. That 
would be like renaming the len() function to "list", since it takes a 
list as argument. Function and class names should be descriptive, giving 
at least a hint as to what they do.

It looks to me that this fName just iterates over the lines in a file, 
which makes it pretty close to just:

for line in open(path + "my_fox"):
    print(line)



> The second generator adds "policy" to the generator processing and
> yields tuples, rather than strings. Each tuple contains the record
> number (from zero), and record length (minus the line end), and the
> record itself (stripped of the line end):

I presume that "record" here means "line", rather than an actual record 
from a flat file with fixed-width fields, or some delimiter other than 
newlines.

for i, line in enumerate(open(pathname + "my_fox")):
    print((i, len(line), line))


>  >>> for record in fnName(path+"my_fox"):
> 	      print(record)

What's "fnName" mean? Perhaps "filename name"? "function name"? Again, 
the name gives no hint as to what the function does.

> def fName(filename):
>      try:
>          fh = open(filename, 'r')
>      except FileNotFoundError as err_code:
>          print (err_code)

For interactive use, this is *just barely* acceptable as a (supposedly) 
user-friendly alternative to a stack trace. 

[Aside: I don't believe that insulating programmers from tracebacks does 
them any favours. Like the Dark Side of the Force, hiding errors is 
seductively attractive, but ultimately harmful, since error tracebacks 
are intimidating to beginners but an essential weapon in the battle 
against buggy code. But reading tracebacks is a skill programmers have to 
learn. Hiding tracebacks does them no favours, it just makes it harder 
for them to learn good debugging skills, and encourages them to treat 
errors as *something to hide* rather than *something to fix*.]

But as a reusable tool for use in non-interactive code, this function 
fails badly. By capturing the exception, it makes it painfully difficult 
for the caller to have control over error-handling. You cannot let the 
exception propagate to some other part of the application for handling; 
you cannot log the exception, or ignore it, or silently swallow the 
exception and try another file. The fName function makes the decision for 
you: it will print the error to standard output (not even standard 
error!) no matter what you want. That's the very essence of *user-
hostile* for library code.

Worse, it's inconsistent! Some errors are handled normally, with an 
exception. It's only FileNotFoundError that is captured and printed. So 
if the user wants to re-use this function and do something with any 
exceptions, she has to use *two* forms of error handling:

(1) wrap it in try...except handler to capture any exception other 
    than FileNotFoundError; and

(2) intercept writes to standard out, capture the error message, and 
    reverse-engineer what went wrong.


instead of just one.


>      else:
>          while True:
>              linein = fh.readline()
>              if (linein!=''):
>                  yield(linein.strip('\n'))
>              else:
>                  break
>          fh.close()

Apart from stripping newlines, which is surely better left to the user 
(what if they need to see the newline? by stripping them automatically, 
the user cannot distinguish between a file which ends with a newline 
character and one which does not), this part is just a re-invention of 
the existing wheel. File objects are already iterable, and yield the 
lines of the file.


>      finally:
>          None

The finally clause is pointless, and not even written idiomatically as a 
do-nothing statement ("pass").


> def fnName(filename):
>      try:
>          fh = open(filename, 'r')
>      except FileNotFoundError as err_code:
>          print (err_code)
>      else:
>          line_count = 0
>          while True:
>              linein = fh.readline()
>              if (linein!=''):
>                  lineout = linein.strip('\n')
>                  length = len(lineout)
>                  yield((line_count, length, lineout))
>                  line_count+=1
>              else:
>                  break
>          fh.close()
>      finally:
>          None


This function re-implements the fName function, except for a simple 
addition. It could be written as:

def fnName(filename):
    for count, line in enumerate(fName(filename)):
        yield (count, len(line), line)




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From harrismh777 at gmail.com  Sat Mar 15 22:52:47 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 15 Mar 2014 21:52:47 -0500
Subject: Sharing: File Reader Generator  with & w/o Policy
References: <lg2h87$6fj$1@speranza.aioe.org>
 <mailman.8156.1394920773.18130.python-list@python.org>
 <lg2te7$oq$1@speranza.aioe.org>
 <mailman.8157.1394933542.18130.python-list@python.org>
Message-ID: <lg33lv$cp7$1@speranza.aioe.org>

On 3/15/14 8:32 PM, Mark Lawrence wrote:

> Start here
> http://docs.python.org/3/library/stdtypes.html#context-manager-types
>

Thanks Mark. I have three books open, and that doc, and wading through. 
You might like to know (as an aside) that I'm done with gg. Got back up 
here with a real news reader and server. All is good that way. gg has 
not been stable over the past three weeks, and this weekend it 
completely quit working. It looks like this reader|client handles the 
line wrapping correctly. whoohoo.

marcus


From python.list at tim.thechases.com  Sat Mar 15 22:58:45 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Sat, 15 Mar 2014 21:58:45 -0500
Subject: Clearing out handlers in logging?
Message-ID: <20140315215845.1e159acf@bigbox.christie.dr>

The current (2.7; maybe 3.x?) logging module doesn't have any sort of
"clear out all the current handlers" method.  I can hack it by doing

  log = logging.getLogger()  # get the root logger
  del log.handlers[:]        # reach inside and nuke 'em
  log.addHandler(...)        # install the one(s) I want

but it feels a little dirty to reach into logging.root.handlers since
there are other methods for adding/removing handlers.  However, as
best I can tell, to remove a handler, you already need to have it
saved somewhere.

Is there a better way to do this, or do I just suck it up and deal
with the (potentially thread-ignorant, as it doesn't lock) hack?

Thanks,

-tkc








From harrismh777 at gmail.com  Sat Mar 15 23:34:52 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 15 Mar 2014 22:34:52 -0500
Subject: Sharing: File Reader Generator  with & w/o Policy
References: <lg2h87$6fj$1@speranza.aioe.org>
 <532505f0$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lg364r$guq$1@speranza.aioe.org>

On 3/15/14 9:01 PM, Steven D'Aprano wrote:
> Reading from files is already pretty simple. I would expect that it will
> be harder to learn the specific details of custom, specialised, file
> readers that *almost*, but not quite, do what you want, than to just
> write a couple of lines of code to do what you need when you need it.
> Particularly for interactive use, where robustness is less important than
> ease of use.

    Yes. What I'm finding is that I'm coding the same 4-6 lines of code 
with every file open (I do want error handling, at least for 
FileNotFoundError) and I only want it to be two lines, read the file 
into a list with error handling.

> What's "policy"?

    That's part of what I personally struggle with (frequently) is do I 
place the policy in the generator, or do I handle it on the outside. For 
instance, I normally strip the line-end and I want to know the record 
lengths. I also may want to know the record number from arrival 
sequence. This policy can be handled in the generator; although, I could 
have handled it outside too.



> for i, line in enumerate(open(pathname + "my_fox")):
>      print((i, len(line), line))

I like it...  and this is where I've always been, when I finally said to 
myself, yuk.  yes, it technically works very well. But, its ugly. And I 
don't mean its technically ugly, I mean its aesthetically ugly and not 
user-easy-to-read.  (I know that's all subjective)

for line in getnumline(path+"my_foxy")):
       print(line)

In this case getnumline() is a generator wrapper around fName(). It of 
course doesn't do anything different than the two lines you listed, but 
it is immediately easier to tell what is happening; even if you're not 
an experienced python programmer.


> [Aside: I don't believe that insulating programmers from tracebacks does
> them any favours.

Yes. I think you're right about that.  But what if they're not 
programmers; what if they're just application users that don't have a 
clue what a trace-back is, and just want to know that the file does not 
exist?  And right away they realize that, oops, I spelled the filename 
wrong.  Yeaah, I struggle with this as I'm trying to simplify, because 
personally I want to see the trace back info.

> Worse, it's inconsistent! Some errors are handled normally, with an
> exception. It's only FileNotFoundError that is captured and printed. So
> if the user wants to re-use this function and do something with any
> exceptions, she has to use *two* forms of error handling:

Yes. The exception handling needs to handle all normal errors.
>
> (1) wrap it in try...except handler to capture any exception other
>      than FileNotFoundError; and
>
> (2) intercept writes to standard out, capture the error message, and
>      reverse-engineer what went wrong.

Ok.


> Apart from stripping newlines, which is surely better left to the user
> (what if they need to see the newline? by stripping them automatically,
> the user cannot distinguish between a file which ends with a newline
> character and one which does not), this part is just a re-invention of
> the existing wheel. File objects are already iterable, and yield the
> lines of the file.

Yes, this is based on my use case, which never needs the line-ends, in 
fact they are a pain. These files are variable record length and the 
only thing the newline is used for is delimiting the records.


>
> def fnName(filename):
>      for count, line in enumerate(fName(filename)):
>          yield (count, len(line), line)
>
I like this, thanks!   enumerate and I are becoming friends.

I like this case philosophically because it is a both | and.  The policy 
is contained in the wrapper generator using enumerate() and len() 
leaving the fName() generator to produce the line.

And you are right about another thing,  I just want to use this thing 
over and over.

for line in getnumline(filename):
     {whatever}

    There does seem to be just one way of doing this (file reads) but 
there are actually many ways of doing this. Is a file object really 
better than a generator, are there good reasons for using the generator, 
are there absolute cases for using a file object?

marcus


From harrismh777 at gmail.com  Sat Mar 15 23:41:27 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 15 Mar 2014 22:41:27 -0500
Subject: test
References: <lg2geg$48n$1@speranza.aioe.org>
 <mailman.8158.1394934532.18130.python-list@python.org>
Message-ID: <lg36h6$hb0$1@speranza.aioe.org>

On 3/15/14 8:48 PM, Travis Griggs wrote:
>
>
>> On Mar 15, 2014, at 14:24, Mark H Harris<harrismh777 at gmail.com>  wrote:
>>
>> test
>
> Pass
Thanks Travis.  I hated doing that.

I have been having a fit with gg, and its taken just a little time to 
get a real news-reader client for posting. What a fit. Google does 
really well with some things, but gg is not one of them, IMHO.

marcus


From rosuav at gmail.com  Sat Mar 15 23:48:36 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 16 Mar 2014 14:48:36 +1100
Subject: Sharing: File Reader Generator with & w/o Policy
In-Reply-To: <lg364r$guq$1@speranza.aioe.org>
References: <lg2h87$6fj$1@speranza.aioe.org>
 <532505f0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lg364r$guq$1@speranza.aioe.org>
Message-ID: <CAPTjJmowUHNvXT-kD+0HbcxABYfr6b40V=bCqkGDDJ4SAdACBA@mail.gmail.com>

On Sun, Mar 16, 2014 at 2:34 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> And you are right about another thing,  I just want to use this thing over
> and over.
>
> for line in getnumline(filename):
>     {whatever}
>
>    There does seem to be just one way of doing this (file reads) but there
> are actually many ways of doing this. Is a file object really better than a
> generator, are there good reasons for using the generator, are there
> absolute cases for using a file object?

I recommend you read up on the Rule of Three. Not the comedic
principle - although that's worth knowing about too - but the
refactoring rule. [1]

As a general rule, code should be put into a function when it's been
done three times the same way. It depends a bit on how similar the
versions are, of course; having two places where the exact same thing
is done might well be enough to refactor, and sometimes you need to
see four or five places doing something only broadly similar before
you can figure out what the common part is, but most of the time,
three usages is the point to give it a name.

There's a cost to refactoring. Suddenly there's a new primitive on the
board - a new piece of language. If you can't give it a good name,
that's potentially a high cost. Splitting out all sorts of things into
generators when you could use well-known primitives like enumerate
gets expensive fast - what's the difference between fName and fnName?
I certainly wouldn't be able to call that, without actually looking
them up.

Let your use-cases justify your refactoring.

ChrisA


[1] https://en.wikipedia.org/wiki/Rule_of_three_(computer_programming)


From harrismh777 at gmail.com  Sun Mar 16 00:47:30 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 15 Mar 2014 23:47:30 -0500
Subject: Sharing: File Reader Generator with & w/o Policy
References: <lg2h87$6fj$1@speranza.aioe.org>
 <532505f0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lg364r$guq$1@speranza.aioe.org>
 <mailman.8160.1394941726.18130.python-list@python.org>
Message-ID: <lg3ad2$obv$1@speranza.aioe.org>

On 3/15/14 10:48 PM, Chris Angelico wrote:
> There's a cost to refactoring. Suddenly there's a new primitive on the
> board - a new piece of language . . . Splitting out all sorts of things into
> generators when you could use well-known primitives like enumerate
> gets expensive fast {snip}
>
>
> [1] https://en.wikipedia.org/wiki/Rule_of_three_(computer_programming)

Very good to remember. I am finding the temptation to make all kinds of 
generators (as you noted above). Its just that the python generator 
makes it so easy to define a function that maintains state between calls 
(of next() in this case) and so its also so easy to want to use them... 
almost forgetting about primitives!

And the rule of three is one of those things that sneaks up on oneself. 
I have actually coded about seven (7) such cases when I discovered that 
they were all identical. I am noticing that folks code the same file 
reader cases "with open() as fh: yadda yadda"  and I've noticed that 
they are all pretty close to the same. Wouldn't it be nice to have one 
simpler getline() or getnumline() name that does this one simple thing 
once and for all. But as simple as it is, it isn't. Well, as you say, 
use cases need to determine code refactoring.

The other thing I'm tempted to do is to find names (even new names) that 
read like English closely (whatever I mean by that) so that there is no 
question about what is going on to a non expert.

for line in getnumline(file):
       {whatever}

Well, what if there were a project called SimplyPy, or some such, that 
boiled the python language down to a (Rexx like) or (BASIC like) syntax 
and usage so that ordinary folks could code out problems (like they did 
in 1964) and expert users could use it too including everything else 
they know about python? Would it be good?

A SimplyPy coder would use constructs similar to other procedural 
languages (like Rexx, Pascal, even C) and without knowing the plethora 
of Python intrinsics could solve problems, yet not be an "expert".

SimplyPy would be a structured subset of the normal language for 
learning and use (very small book/tutorial/ think the Rexx handbook, or 
the K&R).

Its a long way off, and I'm just now experimenting. I'm trying to get my 
hands around context managers (and other things). This is an idea I got 
from Anthony Briggs' Hello Python! (forward SteveHolden) from Manning 
books.  Its very small, lite weight, handles real work, but--- its still 
too big. I am wanting to condense it even further, providing the minimal 
basic core language as an end application product rather than the 
"expert" computer science language that will run under it.

or, over it, as you like.

(you think this is a nutty idea?)

marcus


From rosuav at gmail.com  Sun Mar 16 01:41:53 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 16 Mar 2014 16:41:53 +1100
Subject: Sharing: File Reader Generator with & w/o Policy
In-Reply-To: <lg3ad2$obv$1@speranza.aioe.org>
References: <lg2h87$6fj$1@speranza.aioe.org>
 <532505f0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lg364r$guq$1@speranza.aioe.org>
 <mailman.8160.1394941726.18130.python-list@python.org>
 <lg3ad2$obv$1@speranza.aioe.org>
Message-ID: <CAPTjJmp6ZMVfGPpYfpztCOe2Npfu4PdpOHWBT0OnUgTO=O-v5g@mail.gmail.com>

On Sun, Mar 16, 2014 at 3:47 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/15/14 10:48 PM, Chris Angelico wrote:
>>
>> There's a cost to refactoring. Suddenly there's a new primitive on the
>> board - a new piece of language . . . Splitting out all sorts of things
>> into
>>
>> generators when you could use well-known primitives like enumerate
>> gets expensive fast {snip}
>>
>>
>> [1] https://en.wikipedia.org/wiki/Rule_of_three_(computer_programming)
>
>
> Very good to remember. I am finding the temptation to make all kinds of
> generators (as you noted above). Its just that the python generator makes it
> so easy to define a function that maintains state between calls (of next()
> in this case) and so its also so easy to want to use them... almost
> forgetting about primitives!

General rule of thumb: Every object in the same namespace should be
readily distinguishable by name alone. And if doing that makes your
names so long that the function signature is longer than the function
body, it might be better to not have that as a function :)

Also, I'd consider something code smell if a name is used in only one
place. Maybe not so much with local variables, as there are other
reasons to separate things out, but a function that gets called from
only one place probably doesn't need to exist at top-level. (Of
course, a published API will often seem to have unused or little-used
functions, because they're being provided to the caller. They don't
count.)

> And the rule of three is one of those things that sneaks up on oneself. I
> have actually coded about seven (7) such cases when I discovered that they
> were all identical. I am noticing that folks code the same file reader cases
> "with open() as fh: yadda yadda"  and I've noticed that they are all pretty
> close to the same. Wouldn't it be nice to have one simpler getline() or
> getnumline() name that does this one simple thing once and for all. But as
> simple as it is, it isn't. Well, as you say, use cases need to determine
> code refactoring.

If getline() is doing nothing that the primitive doesn't, and
getnumline is just enumerate, then they're not achieving anything
beyond shielding you from the primitives.

> The other thing I'm tempted to do is to find names (even new names) that
> read like English closely (whatever I mean by that) so that there is no
> question about what is going on to a non expert.
>
> for line in getnumline(file):
>       {whatever}

The trouble is that your idea of getnumline(file) might well differ
from someone else's idea of getnumline(file). Using Python's
primitives removes that confusion - if you see enumerate(file), you
know exactly what it's doing, even in someone else's code.

> Well, what if there were a project called SimplyPy, or some such, that
> boiled the python language down to a (Rexx like) or (BASIC like) syntax and
> usage so that ordinary folks could code out problems (like they did in 1964)
> and expert users could use it too including everything else they know about
> python? Would it be good?
>
> A SimplyPy coder would use constructs similar to other procedural languages
> (like Rexx, Pascal, even C) and without knowing the plethora of Python
> intrinsics could solve problems, yet not be an "expert".
>
> SimplyPy would be a structured subset of the normal language for learning
> and use (very small book/tutorial/ think the Rexx handbook, or the K&R).
>
> Its a long way off, and I'm just now experimenting. I'm trying to get my
> hands around context managers (and other things). This is an idea I got from
> Anthony Briggs' Hello Python! (forward SteveHolden) from Manning books.  Its
> very small, lite weight, handles real work, but--- its still too big. I am
> wanting to condense it even further, providing the minimal basic core
> language as an end application product rather than the "expert" computer
> science language that will run under it.
>
> or, over it, as you like.
>
> (you think this is a nutty idea?)

To be quite frank, yes I do think it's a nutty idea. Like most nutty
things, there's a kernel of something good in it, but that's not
enough to build a system on :)

Python is already pretty simple. The trouble with adding a layer of
indirection is that you'll generally be limiting what the code can do,
which is usually a bad idea for a general purpose programming
language, and also forcing you to predict everything the programmer
might want to do. Or you might have an "escape clause" that lets the
programmer drop to "real Python"... but as soon as you allow that, you
suddenly force the subsequent reader to comprehend all of Python,
defeating the purpose.

We had a discussion along these lines a little while ago, about
designing a DSL [1] for window creation. On one side of the debate was
"hey look how much cleaner the code is if I use this DSL", and on the
other side was "hey look how much work you don't have to do if you
just write code directly". The more cushioning between the programmer
and the language, the more the cushion has to be built to handle
everything the programmer might want to do. Python is a buffer between
me and C. C is itself a buffer between me and assembly language. Each
of them provides something that I want, but each of them has to be so
extensive as to be able to handle _anything_ I might want to write.
(Or, pretty much anything. Sometimes I find that a high level language
lacks some little thing - recently I was yearning for a beep feature -
and find that I can shell out to some external utility to do it for
me.) Creating SimplyPy would put the onus on you to make it possible
to write general code in it, and I think you'll find it's just not
worth trying - more and more you'll want to add features from Python
itself, until you achieve the inner-platform effect. [2]

Note that there are times when this sort of cushioning and limiting
are absolutely appropriate. Sometimes you want to limit end users to
certain pieces of functionality only, and the easiest way to do it is
to create a special-purpose language that is interpreted by a (say)
Python script. Or maybe you want to write a dice roller that takes a
specific notation like "2d8 + d6 (fire) + 2d6 (sneak attack) + 4
(STR)" [3] and interprets that appropriately. But the idea isn't to
simplify general programming, then, and if you're doing that sort of
thing, you still might want to consider a general-purpose language
(Lua's good for that, as is JavaScript/ECMAScript). That's not what
you're suggesting.

ChrisA

[1] Domain-specific language. I'm never sure whether to footnote these
kinds of acronyms, but I want to clarify that I am not talking about a
copper-based internet connection here.
[2] http://thedailywtf.com/Articles/The_Inner-Platform_Effect.aspx and
https://en.wikipedia.org/wiki/Inner-platform_effect
[3] I actually have a dice roller that does exactly that as part of
Minstrel Hall - http://minstrelhall.com/


From harrismh777 at gmail.com  Sun Mar 16 02:19:52 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sun, 16 Mar 2014 01:19:52 -0500
Subject: Sharing: File Reader Generator with & w/o Policy
References: <lg2h87$6fj$1@speranza.aioe.org>
 <532505f0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lg364r$guq$1@speranza.aioe.org>
 <mailman.8160.1394941726.18130.python-list@python.org>
 <lg3ad2$obv$1@speranza.aioe.org>
 <mailman.8161.1394948516.18130.python-list@python.org>
Message-ID: <lg3fq7$25s$1@speranza.aioe.org>

On 3/16/14 12:41 AM, Chris Angelico wrote:
>

    Good stuff Chris, and thanks for the footnotes, I appreciate it.

> If getline() is doing nothing that the primitive doesn't, and
> getnumline is just enumerate, then they're not achieving anything
> beyond shielding you from the primitives.
>

    Yes.  getline(fn) is returning the raw line minus the newline \n. 
And getnumline(fn) is 1) creating a name that is easily recognizable, 
and 2) shielding the 'user' from the primitives; yup.

> The trouble is that your idea of getnumline(file) might well differ
> from someone else's idea of getnumline(file). Using Python's
> primitives removes that confusion

    I am seeing that; esp for folks used to seeing the primitives; don't 
want confusion.

> To be quite frank, yes I do think it's a nutty idea. Like most nutty
> things, there's a kernel of something good in it, but that's not
> enough to build a system on :)

    Thanks for your candor. I appreciate that too. Well, like I said, 
I'm just experimenting with the idea right now, just playing around 
really. In the process I'm coming more up-to-speed with python3.3 all 
the time.   :)

>
> Python is already pretty simple.

    statement == True

>
> We had a discussion along these lines a little while ago, about
> designing a DSL [1] for window creation. On one side of the debate was
> "hey look how much cleaner the code is if I use this DSL", and on the
> other side was "hey look how much work you don't have to do if you
> just write code directly".

    Was that on python-dev, or python-ideas, or here?   I'd like to read 
through it sometime.

Well just for grins, here is the updated my_utils.py for compare with 
where I started tonight, ending like before with the code:

 >>>
 >>> for line in getline(path+"my_foxy"):
	print (line)

The quick brown fox jumped
over the lazy dog's tail.

Now is the time for all
good women to come to the
aid of computer science!

 >>> for line in getnumline(path+"my_foxy"):
	print (line)
	
(0, 26, 'The quick brown fox jumped')
(1, 25, "over the lazy dog's tail.")
(2, 0, '')
(3, 23, 'Now is the time for all')
(4, 25, 'good women to come to the')
(5, 24, 'aid of computer science!')

 >>> for line in getline(path+"my_utils.py"):
	print (line)

#---------------------------------------------------------
# __fOpen__(filename)   generator: file open internal
#---------------------------------------------------------
def __fOpen__(filename):
     try:
         with open(filename, 'r') as fh:
             for linein in fh:
                 yield linein.strip('\n')
     except FileNotFoundError as err_code:
         print(err_code)
         # think about error handling, logging
     finally:
         pass

#---------------------------------------------------------
# getnumline(filename)  generator: enumerated file reader
#---------------------------------------------------------
def getnumline(filename):
     for count, line in enumerate(__fOpen__(filename)):
         yield((count, len(line), line))

#---------------------------------------------------------
# getline(filename)   generator: raw file reader iterable
#---------------------------------------------------------
def getline(filename):
     for line in __fOpen__(filename):
         yield(line)

#---------------------------------------------------------
# {next util}
#---------------------------------------------------------
 >>>


From rosuav at gmail.com  Sun Mar 16 02:37:17 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 16 Mar 2014 17:37:17 +1100
Subject: Sharing: File Reader Generator with & w/o Policy
In-Reply-To: <lg3fq7$25s$1@speranza.aioe.org>
References: <lg2h87$6fj$1@speranza.aioe.org>
 <532505f0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lg364r$guq$1@speranza.aioe.org>
 <mailman.8160.1394941726.18130.python-list@python.org>
 <lg3ad2$obv$1@speranza.aioe.org>
 <mailman.8161.1394948516.18130.python-list@python.org>
 <lg3fq7$25s$1@speranza.aioe.org>
Message-ID: <CAPTjJmpi4seWaMn9sU79_Q1ORLau6pPBKXpQJZdkirZ0nRmRTQ@mail.gmail.com>

On Sun, Mar 16, 2014 at 5:19 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/16/14 12:41 AM, Chris Angelico wrote:
>> To be quite frank, yes I do think it's a nutty idea. Like most nutty
>> things, there's a kernel of something good in it, but that's not
>> enough to build a system on :)
>
>
>    Thanks for your candor. I appreciate that too. Well, like I said, I'm
> just experimenting with the idea right now, just playing around really. In
> the process I'm coming more up-to-speed with python3.3 all the time.   :)

Good, glad you can take it the right way :) Learning is not by doing
whatever you like and being told "Oh yes, very good job" like in
kindergarten. Learning is by doing something (or proposing doing
something) and getting solid feedback. Of course, that feedback may be
wrong - your idea might be brilliant even though I believe it's a bad
one - and you need to know when to stick to your guns and drive your
idea forward through the hail of oncoming ... okay, this metaphor's
getting a bit tangled in its own limbs... okay, the meta-metaphor is
getting... alright I'm stopping now.

>> We had a discussion along these lines a little while ago, about
>> designing a DSL [1] for window creation. On one side of the debate was
>> "hey look how much cleaner the code is if I use this DSL", and on the
>> other side was "hey look how much work you don't have to do if you
>> just write code directly".
>
>    Was that on python-dev, or python-ideas, or here?   I'd like to read
> through it sometime.

Was here on python-list:

https://mail.python.org/pipermail/python-list/2014-January/664617.html
https://mail.python.org/pipermail/python-list/2014-January/thread.html#664617

The thread rambled a bit, but if you like reading, there's some good
content in there. You'll see some example code from my Pike MUD
client, Gypsum, and Steven D'Aprano and I discuss it. If you'd rather
skip most of the thread and just go to the bits I'm talking about,
here's my explanation of the Pike code:

https://mail.python.org/pipermail/python-list/2014-January/665286.html

And here's Steven's take on it:

https://mail.python.org/pipermail/python-list/2014-January/665356.html

And keep reading from there. TL;DR: It's not perfect as a DSL, but
it's jolly good as something that is already there and takes no
effort.

ChrisA


From gd.usenet at spamfence.net  Sun Mar 16 04:39:40 2014
From: gd.usenet at spamfence.net (Gunther Dietrich)
Date: Sun, 16 Mar 2014 09:39:40 +0100
Subject: Clearing out handlers in logging?
References: <mailman.8159.1394938715.18130.python-list@python.org>
Message-ID: <gd.usenet-B1805D.09394016032014@dwarf.main.lan>

Tim Chase <python.list at tim.thechases.com> wrote:

>The current (2.7; maybe 3.x?) logging module doesn't have any sort of
>"clear out all the current handlers" method.

Indeed, THERE IS a removeHandler() method. In the documentation of 
python 2.6, it is mentioned in '16.6.5. Logger Objects', directly after 
the addHandler() method. If you found the addHandler() method there, you 
should have found removeHandler() too.

And a simple

>>> dir(log)
['__doc__', '__init__', '__module__', '_log', 'addFilter', 'addHandler', 
'callHandlers', 'critical', 'debug', 'disabled', 'error', 'exception', 
'fatal', 'filter', 'filters', 'findCaller', 'getEffectiveLevel', 
'handle', 'handlers', 'info', 'isEnabledFor', 'level', 'log', 
'makeRecord', 'manager', 'name', 'parent', 'propagate', 'removeFilter', 
'removeHandler', 'root', 'setLevel', 'warn', 'warning']

also would have revealed it to you.


>I can hack it by doing
>
>  log = logging.getLogger()  # get the root logger
>  del log.handlers[:]        # reach inside and nuke 'em
>  log.addHandler(...)        # install the one(s) I want
>
>but it feels a little dirty to reach into logging.root.handlers since
>there are other methods for adding/removing handlers.  However, as
>best I can tell, to remove a handler, you already need to have it
>saved somewhere.

What about this:

>>> for handler in log.handlers:
...     log.removeHandler(handler)

I think, that's just one of the tasks that removeHandler() was written 
for.


>Is there a better way to do this, or do I just suck it up and deal
>with the (potentially thread-ignorant, as it doesn't lock) hack?

One of the best ways would be to read the documentation. And to do some 
exploration, e.g. by means of dir() and help(), could also be quite 
instructive. This experience cannot be replaced by 
documentation-research requests to the Usenet.



Best regards,

Gunther


From rosuav at gmail.com  Sun Mar 16 05:02:57 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 16 Mar 2014 20:02:57 +1100
Subject: Clearing out handlers in logging?
In-Reply-To: <gd.usenet-B1805D.09394016032014@dwarf.main.lan>
References: <mailman.8159.1394938715.18130.python-list@python.org>
 <gd.usenet-B1805D.09394016032014@dwarf.main.lan>
Message-ID: <CAPTjJmrkOEm4f=edn4MmA0aikyhvX5w1jZSbST2FwE6EvxCz1Q@mail.gmail.com>

On Sun, Mar 16, 2014 at 7:39 PM, Gunther Dietrich
<gd.usenet at spamfence.net> wrote:
>>but it feels a little dirty to reach into logging.root.handlers since
>>there are other methods for adding/removing handlers.  However, as
>>best I can tell, to remove a handler, you already need to have it
>>saved somewhere.
>
> What about this:
>
>>>> for handler in log.handlers:
> ...     log.removeHandler(handler)
>
> I think, that's just one of the tasks that removeHandler() was written
> for.

I'm sure Tim was aware of the removeHandler function. But this is
still reaching into log.handlers - although IMO it's safer to reach in
and read than to reach in and mutate. So without the implications of
Tim's inability to read docs, this is a viable suggestion. I'd prefer
this over the original "del log.handlers[:]".

ChrisA


From __peter__ at web.de  Sun Mar 16 05:18:15 2014
From: __peter__ at web.de (Peter Otten)
Date: Sun, 16 Mar 2014 10:18:15 +0100
Subject: Clearing out handlers in logging?
References: <mailman.8159.1394938715.18130.python-list@python.org>
 <gd.usenet-B1805D.09394016032014@dwarf.main.lan>
Message-ID: <lg3q8a$2p7$1@ger.gmane.org>

Gunther Dietrich wrote:

> Tim Chase <python.list at tim.thechases.com> wrote:
> 
>>The current (2.7; maybe 3.x?) logging module doesn't have any sort of
>>"clear out all the current handlers" method.
> 
> Indeed, THERE IS a removeHandler() method. In the documentation of
> python 2.6, it is mentioned in '16.6.5. Logger Objects', directly after
> the addHandler() method. If you found the addHandler() method there, you
> should have found removeHandler() too.
> 
> And a simple
> 
>>>> dir(log)
> ['__doc__', '__init__', '__module__', '_log', 'addFilter', 'addHandler',
> 'callHandlers', 'critical', 'debug', 'disabled', 'error', 'exception',
> 'fatal', 'filter', 'filters', 'findCaller', 'getEffectiveLevel',
> 'handle', 'handlers', 'info', 'isEnabledFor', 'level', 'log',
> 'makeRecord', 'manager', 'name', 'parent', 'propagate', 'removeFilter',
> 'removeHandler', 'root', 'setLevel', 'warn', 'warning']
> 
> also would have revealed it to you.
> 
> 
>>I can hack it by doing
>>
>>  log = logging.getLogger()  # get the root logger
>>  del log.handlers[:]        # reach inside and nuke 'em
>>  log.addHandler(...)        # install the one(s) I want
>>
>>but it feels a little dirty to reach into logging.root.handlers since
>>there are other methods for adding/removing handlers.  However, as
>>best I can tell, to remove a handler, you already need to have it
>>saved somewhere.
> 
> What about this:
> 
>>>> for handler in log.handlers:
> ...     log.removeHandler(handler)
> 
> I think, that's just one of the tasks that removeHandler() was written
> for.
> 
> 
>>Is there a better way to do this, or do I just suck it up and deal
>>with the (potentially thread-ignorant, as it doesn't lock) hack?
> 
> One of the best ways would be to read the documentation. And to do some
> exploration, e.g. by means of dir() and help(), could also be quite
> instructive. This experience cannot be replaced by
> documentation-research requests to the Usenet.

Hm, what do the docs say about this one?

>>> import logging
>>> logging.basicConfig()
>>> log = logging.getLogger("foo")
>>> for i in range(5):
...     log.addHandler(logging.FileHandler("tmp.log"))
... 
>>> assert len(log.handlers) == 5
>>> for handler in log.handlers:
...     log.removeHandler(handler)
... 
>>> log.handlers
[<logging.FileHandler object at 0x7f8217686e90>, <logging.FileHandler object 
at 0x7f8216f9eb90>]




From rosuav at gmail.com  Sun Mar 16 05:35:19 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 16 Mar 2014 20:35:19 +1100
Subject: Clearing out handlers in logging?
In-Reply-To: <lg3q8a$2p7$1@ger.gmane.org>
References: <mailman.8159.1394938715.18130.python-list@python.org>
 <gd.usenet-B1805D.09394016032014@dwarf.main.lan>
 <lg3q8a$2p7$1@ger.gmane.org>
Message-ID: <CAPTjJmookm=byjqEAH5y8bwHGhTJHw9w5Ha_Tg-fPzd64R0Vuw@mail.gmail.com>

On Sun, Mar 16, 2014 at 8:18 PM, Peter Otten <__peter__ at web.de> wrote:
> Hm, what do the docs say about this one?
>
>>>> import logging
>>>> logging.basicConfig()
>>>> log = logging.getLogger("foo")
>>>> for i in range(5):
> ...     log.addHandler(logging.FileHandler("tmp.log"))
> ...
>>>> assert len(log.handlers) == 5
>>>> for handler in log.handlers:
> ...     log.removeHandler(handler)
> ...
>>>> log.handlers
> [<logging.FileHandler object at 0x7f8217686e90>, <logging.FileHandler object
> at 0x7f8216f9eb90>]

for handler in log.handlers[:]:
    log.removeHandler(handler)

ChrisA


From kwpolska at gmail.com  Sun Mar 16 06:07:04 2014
From: kwpolska at gmail.com (=?UTF-8?B?Q2hyaXMg4oCcS3dwb2xza2HigJ0gV2Fycmljaw==?=)
Date: Sun, 16 Mar 2014 11:07:04 +0100
Subject: test
In-Reply-To: <lg36h6$hb0$1@speranza.aioe.org>
References: <lg2geg$48n$1@speranza.aioe.org>
 <mailman.8158.1394934532.18130.python-list@python.org>
 <lg36h6$hb0$1@speranza.aioe.org>
Message-ID: <CAMw+j7KYnS3Khm2sxXBowLRBVGh+rWD5qE2c2mj5o_GwYrvfuw@mail.gmail.com>

On Sun, Mar 16, 2014 at 4:41 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> I have been having a fit with gg, and its taken just a little time to get a
> real news-reader client for posting. What a fit. Google does really well
> with some things, but gg is not one of them, IMHO.

Why not use the mailing list instead?  It?s a much easier way to
access this place.

https://mail.python.org/mailman/listinfo/python-list

-- 
Chris ?Kwpolska? Warrick <http://kwpolska.tk>
PGP: 5EAAEA16
stop html mail | always bottom-post | only UTF-8 makes sense


From steve+comp.lang.python at pearwood.info  Sun Mar 16 06:36:28 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 16 Mar 2014 10:36:28 GMT
Subject: Sharing: File Reader Generator with & w/o Policy
References: <lg2h87$6fj$1@speranza.aioe.org>
 <532505f0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lg364r$guq$1@speranza.aioe.org>
 <mailman.8160.1394941726.18130.python-list@python.org>
 <lg3ad2$obv$1@speranza.aioe.org>
Message-ID: <53257eab$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sat, 15 Mar 2014 23:47:30 -0500, Mark H Harris wrote:

> The other thing I'm tempted to do is to find names (even new names) that
> read like English closely (whatever I mean by that) so that there is no
> question about what is going on to a non expert.
> 
> for line in getnumline(file):
>        {whatever}

I'm not an expert on your code, and I have very little idea what that is 
supposed to do. Judging by the name "getnumline", my first guess is that 
the function takes a line number n, and it will return the nth line of 
some source:

getnumline(source, 5)
=> returns the 5th line from source

But that's not how you use it. You pass it a "file". Is that a file 
object, or a file name? My guess is that it would be a file object, since 
if you wanted a file name you would have written getnumline(filename). Is 
that a file object that is open for reading or writing? I'd have to guess 
that it's open for reading, since you're (probably?) "getting" from the 
file rather than "putting".

So... something like this:

file = open("some thing")
for line in getnumline(file):
    ...

Presumably it iterates over the lines of the file, but what it does with 
the lines is hard to say. If I had to guess, I'd say... maybe it's 
extracting the lines that start with a line number? Something like this 
perhaps?

def getnumline(file_object):
    count = 0  # Or start at 1?
    while True:
        line = file_object.readline()
        if line == '':
            break
        if line.startswith(str(count)):
            yield line
        count += 1

But this is only a guess, based on the assumption that while the function 
name is misleading, it's not *entirely* misleading. I'm puzzled why the 
function claims to do something with "line" singular, when you're 
obviously using it to iterate over lines plural.

Contrast that with an example from the Python built-ins: enumerate. What 
you get is exactly what it says on the tin: the function is called 
enumerate, and enumerate is what it does:


enumerate
    v 1: specify individually; "She enumerated the many obstacles
         she had encountered"; "The doctor recited the list of
         possible side effects of the drug" [syn: enumerate,
         recite, itemize, itemise]
    2: determine the number or amount of; "Can you count the books
       on your shelf?"; "Count your change" [syn: count, number,
       enumerate, numerate]



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From python.list at tim.thechases.com  Sun Mar 16 08:57:59 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Sun, 16 Mar 2014 07:57:59 -0500
Subject: Clearing out handlers in logging?
In-Reply-To: <gd.usenet-B1805D.09394016032014@dwarf.main.lan>
References: <mailman.8159.1394938715.18130.python-list@python.org>
 <gd.usenet-B1805D.09394016032014@dwarf.main.lan>
Message-ID: <20140316075759.019a0525@bigbox.christie.dr>

On 2014-03-16 09:39, Gunther Dietrich wrote:
> Tim Chase <python.list at tim.thechases.com> wrote:
> 
> >The current (2.7; maybe 3.x?) logging module doesn't have any sort
> >of "clear out all the current handlers" method.
> 
> Indeed, THERE IS a removeHandler() method.

Yes, I'm aware of it, having read the source & docs.  However, the
signature is

  removeHandler(some_handle_to_a_handler_that_you_already_have)

and at the point in my code where I need to override this,
basicConfig() has already assigned a default stream handler and
discarded the handle/name/reference to it because
the .debug/.info/.warn/.error/.critical methods of all call
basicConfig() if there aren't any handlers.

[Aside: which is non-pythonically, using "if len(self.handlers) == 0"
instead of "if not self.handlers" in addition to the camel-case
naming (which would be much harder to fix)]

> >>> for handler in log.handlers:
> ...     log.removeHandler(handler)
> 
> I think, that's just one of the tasks that removeHandler() was
> written for.

The question revolves mostly around dipping your hands into the
undocumented .handlers property.  I can nuke it directly (and looking
at least at the 2.7 source, there doesn't seem to be much issue with
doing this), or I can iterate (as modified by Chris Angelico to
prevent modifying the list over which you're iterating). Either way,
it still involves reaching into log.handlers which doesn't appear in
any of the documentation as far as I could find.

So yes, I use help() and dir() on a daily basis.  But just because
something is there doesn't mean I should go mucking with it in the
event it's undocumented.  If it *should* be trusted as a publicly
available interface, it should be documented; if it shouldn't be
treated publicly, then it should have a way to iterate over them
such as

  def iterHandlers(self):
    for h in self.handlers[:]:
      yield h

so you can do

  for h in log.iterHandlers():
    log.removeHandler(h)

Given how stable this code has been over the years, I'd just document
the log.handlers property and possibly advise to lock around messing
with it (unless "del log.handlers[:]" is atomic).

-tkc








From dan.h.mcinerney at gmail.com  Sun Mar 16 09:24:45 2014
From: dan.h.mcinerney at gmail.com (Dan McInerney)
Date: Sun, 16 Mar 2014 09:24:45 -0400
Subject: Thread is somehow interfering with a while loop called after the
 thread is started
Message-ID: <CAO9iXYYYvxfbEjEZ8CKRJeMjTn9p82jHfs0V15L6Gkoa=kNCvw@mail.gmail.com>

Coming back to this a long time later. I figured it out a little bit after
I posted this. I wasn't aware that q.try_run() within the nfqueue module
was a blocking call
https://www.wzdftpd.net/redmine/projects/nfqueue-bindings/wiki/Examples.
I'm not sure I was even aware of what it meant to be blocking vs
nonblocking. Either way, someone from #python looked at my code and told me
nfqueue is a blocking call and I should look into something like twisted.

Twisted is a complex module but I spent a bunch of time looking at it and
eventually had some working code implementing the absolute bare essentials
as I needed them to go asynchronous. This question eventually progressed
into https://github.com/DanMcInerney/LANs.py.

Speaking of network concurrency, my recent project has been from a web
scraper point of view and I think gevents+requests or gevents+mechanize are
the way to go for that somewhat-related topic. erequests won't import due
to a bug, grequests has no way to handle exceptions in the fetching of
responses, treq can't find and fill out form logins (maybe with a POST,
haven't explored that route), and scrapy is way too big and complex for my
latest project (https://github.com/DanMcInerney/shodan_pharmer), eventlets
I'm sure CAN work with libraries other than urllib2 but it implements and
imports its own urllib2 and it is not a favorable time:effort ratio for me
to try and implement that.
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From laguna-mc at mail.com  Sun Mar 16 09:50:15 2014
From: laguna-mc at mail.com (laguna-mc at mail.com)
Date: Sun, 16 Mar 2014 09:50:15 -0400
Subject: Installing addition libraries in Portable Python 2.7 on Windows
Message-ID: <20140316135015.292040@gmx.com>

I am new in Python, I have Portable Python 2.7.5.1 installed on Windows 7.

I want to install additional libraries:

python-magic
libmagic
libfuzzy
pyqtgraph

I downloaded package, saved on hard drive, unzipped, find setup.py and tried install via Command Prompt:

Python-Portable.exe setup.py install

A new DOS terminal window briefly flashes and disappears, without showing any error or installation confirmation.
I assume that nothing has been installed and/or installation failed.. No tips or errors has been shown, so I don't' know how to install these packages corretcly.
I tried also to install get-pip.py use same way, and again nothing happens, no any errors or results.
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From breamoreboy at yahoo.co.uk  Sun Mar 16 11:06:28 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 16 Mar 2014 15:06:28 +0000
Subject: Installing addition libraries in Portable Python 2.7 on Windows
In-Reply-To: <20140316135015.292040@gmx.com>
References: <20140316135015.292040@gmx.com>
Message-ID: <lg4el6$ds5$1@ger.gmane.org>

On 16/03/2014 13:50, laguna-mc at mail.com wrote:
> I am new in Python, I have Portable Python 2.7.5.1 installed on Windows 7.
>
> I want to install additional libraries:
>
> python-magic
> libmagic
> libfuzzy
> pyqtgraph
>
> I downloaded package, saved on hard drive, unzipped, find setup.py and
> tried install via Command Prompt:
>
> Python-Portable.exe setup.py install
>
> A new DOS terminal window briefly flashes and disappears, without
> showing any error or installation confirmation.
> I assume that nothing has been installed and/or installation failed.. No
> tips or errors has been shown, so I don't' know how to install these
> packages corretcly.
> I tried also to install get-pip.py use same way, and again nothing
> happens, no any errors or results.
>

IIRC you need to obtain ez_setup.py to get easy_install and only then 
will get-pip.py work.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From gd.usenet at spamfence.net  Sun Mar 16 14:29:46 2014
From: gd.usenet at spamfence.net (Gunther Dietrich)
Date: Sun, 16 Mar 2014 19:29:46 +0100
Subject: Clearing out handlers in logging?
References: <mailman.8159.1394938715.18130.python-list@python.org>
 <gd.usenet-B1805D.09394016032014@dwarf.main.lan>
 <mailman.8167.1394974663.18130.python-list@python.org>
Message-ID: <gd.usenet-EA8AA5.19294616032014@dwarf.main.lan>

Tim Chase <python.list at tim.thechases.com> wrote:

>> >The current (2.7; maybe 3.x?) logging module doesn't have any sort
>> >of "clear out all the current handlers" method.
>> 
>> Indeed, THERE IS a removeHandler() method.
>
>Yes, I'm aware of it, having read the source & docs.  However, the
>signature is

Sorry, your original article lacks information about what you already 
know/tried and what not. So it is a bit misleading and makes the 
impression, you would't read the documentation. It would have been 
helpful if you had told us your preconditions.



Best regards,

Gunther


From contest at kivy.org  Sun Mar 16 13:42:16 2014
From: contest at kivy.org (qua-non)
Date: Sun, 16 Mar 2014 23:12:16 +0530
Subject: Kivy contest 2014
Message-ID: <CAPztPCf9PzfjJ5E1Cw8Ami5aYDBxDZAz8txv81GduHC6wTdKQQ@mail.gmail.com>

Hi folks,

Kivy will be holding it's programming contest for 2014 starting April 15th.

For details please visit http://kivy.org/#contest

If you are interested in sponsoring the contest, please contact us at
contest at kivy.org.


[image: Inline image 1]
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From python.list at tim.thechases.com  Sun Mar 16 14:50:26 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Sun, 16 Mar 2014 13:50:26 -0500
Subject: Clearing out handlers in logging?
In-Reply-To: <gd.usenet-EA8AA5.19294616032014@dwarf.main.lan>
References: <mailman.8159.1394938715.18130.python-list@python.org>
 <gd.usenet-B1805D.09394016032014@dwarf.main.lan>
 <mailman.8167.1394974663.18130.python-list@python.org>
 <gd.usenet-EA8AA5.19294616032014@dwarf.main.lan>
Message-ID: <20140316135026.6a5e21ef@bigbox.christie.dr>

On 2014-03-16 19:29, Gunther Dietrich wrote:
> >> Indeed, THERE IS a removeHandler() method.  
> >
> >Yes, I'm aware of it, having read the source & docs.  However, the
> >signature is  
> 
> Sorry, your original article lacks information about what you
> already know/tried and what not. So it is a bit misleading and
> makes the impression, you would't read the documentation. It would
> have been helpful if you had told us your preconditions.

Heh, I tried to make that clear in my initial posting with the "since
there are other methods for adding/removing handlers" bit.  I guess I
could have been more explicit though as to what I'd tried.  I
generally figure that, if someone knows enough to dig into the
stdlib's source code, they also know enough to use dir() and help().
Not *always* the case, but a good hint that they're past the basics.

But I could have clarified my question more along the lines of
"Should log.handlers be public/documented; should Logger grow
clearHandlers() and iterHandlers() methods; or should I wantonly use
log.handlers but then just get to keep both pieces if/when it breaks?"

-tkc





From laguna-mc at mail.com  Sun Mar 16 16:31:18 2014
From: laguna-mc at mail.com (laguna-mc at mail.com)
Date: Sun, 16 Mar 2014 16:31:18 -0400
Subject: Installing addition libraries in Portable Python 2.7 on Windows
Message-ID: <20140316203119.292070@gmx.com>

It'slike a chain, eachnew modulepulls afew othermodules.I can postpone get-pip.py onthe very last stage, now I want to install python-magic, libmagic, libfuzzy, pyqtgraph. How to do this?

----- Original Message -----
From: Mark Lawrence
Sent: 03/16/14 05:06 PM
To: python-list at python.org
Subject: Re: Installing addition libraries in Portable Python 2.7 on Windows

On 16/03/2014 13:50, laguna-mc at mail.com wrote: > I am new in Python, I have Portable Python 2.7.5.1 installed on Windows 7. > > I want to install additional libraries: > > python-magic > libmagic > libfuzzy > pyqtgraph > > I downloaded package, saved on hard drive, unzipped, find setup.py and > tried install via Command Prompt: > > Python-Portable.exe setup.py install > > A new DOS terminal window briefly flashes and disappears, without > showing any error or installation confirmation. > I assume that nothing has been installed and/or installation failed.. No > tips or errors has been shown, so I don't' know how to install these > packages corretcly. > I tried also to install get-pip.py use same way, and again nothing > happens, no any errors or results. > IIRC you need to obtain ez_setup.py to get easy_install and only then will get-pip.py work. -- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language. Mark Lawrence --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com -- https://mail.python.org/mailman/listinfo/python-list
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From laguna-mc at mail.com  Sun Mar 16 21:20:54 2014
From: laguna-mc at mail.com (laguna-mc at mail.com)
Date: Sun, 16 Mar 2014 21:20:54 -0400
Subject: Error when installing matplotlib-1.3. on Windows
Message-ID: <20140317012054.292060@gmx.com>

I'm trying to install matplotlib from locally stored source archive file (Portable Python 2.7 on Windows):

pip install E:\matplotlib-1.3.1.win32-py2.7.exe

Got error, below is log:


E:\Portable Python 2.7.5.1\App\Scripts\pip run on 03/17/14 03:10:16
Exception:
Traceback (most recent call last):
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\basecommand.py", line 122, in main
 status = self.run(options, args)
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\commands\install.py", line 257, in run
 InstallRequirement.from_line(name, None))
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line 172, in from_line
 return cls(req, comes_from, url=url, prereleases=prereleases)
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line 70, in __init__
 req = pkg_resources.Requirement.parse(req)
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2606, in parse
 reqs = list(parse_requirements(s))
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2544, in parse_requirements
 line, p, specs = scan_list(VERSION,LINE_END,line,p,(1,2),"version spec")
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2512, in scan_list
 raise ValueError("Expected "+item_name+" in",line,"at",line[p:])
ValueError: ('Expected version spec in', 'E:\\matplotlib-1.3.1.win32-py2.7.exe', 'at', ':\\matplotlib-1.3.1.win32-py2.7.exe')


What is the problem and how to solve it?
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From python at mrabarnett.plus.com  Sun Mar 16 21:55:39 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 17 Mar 2014 01:55:39 +0000
Subject: Error when installing matplotlib-1.3. on Windows
In-Reply-To: <20140317012054.292060@gmx.com>
References: <20140317012054.292060@gmx.com>
Message-ID: <5326561B.3070006@mrabarnett.plus.com>

On 2014-03-17 01:20, laguna-mc at mail.com wrote:
> I'm trying to install matplotlib from locally stored source archive file
> (Portable Python 2.7 on Windows):
>
> pip install E:\matplotlib-1.3.1.win32-py2.7.exe
>
> Got error, below is log:
>
>
> E:\Portable Python 2.7.5.1\App\Scripts\pip run on 03/17/14 03:10:16
> Exception:
> Traceback (most recent call last):
>    File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\basecommand.py", line 122, in main
>      status = self.run(options, args)
>    File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\commands\install.py", line 257, in run
>      InstallRequirement.from_line(name, None))
>    File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py",
> line 172, in from_line
>      return cls(req, comes_from, url=url, prereleases=prereleases)
>    File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py",
> line 70, in __init__
>      req = pkg_resources.Requirement.parse(req)
>    File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2606,
> in parse
>      reqs = list(parse_requirements(s))
>    File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2544,
> in parse_requirements
>      line, p, specs = scan_list(VERSION,LINE_END,line,p,(1,2),"version
> spec")
>    File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2512,
> in scan_list
>      raise ValueError("Expected "+item_name+" in",line,"at",line[p:])
> ValueError: ('Expected version spec in',
> 'E:\\matplotlib-1.3.1.win32-py2.7.exe', 'at',
> ':\\matplotlib-1.3.1.win32-py2.7.exe')
>
>
> What is the problem and how to solve it?
>
Judging by the name, I'd say that "matplotlib-1.3.1.win32-py2.7.exe" is
an installer, so you just need to run it.


From jobmattcon at gmail.com  Sun Mar 16 23:54:35 2014
From: jobmattcon at gmail.com (jobmattcon at gmail.com)
Date: Sun, 16 Mar 2014 20:54:35 -0700 (PDT)
Subject: File "build\bdist.win32\egg\redis\client.py", line 705, in get
Message-ID: <249e4d57-3619-4b07-ae52-e083bcbd48af@googlegroups.com>

in win32 with redis-py and redis for window

Traceback (most recent call last):
  File "testredis.py", line 21, in <module>
    matrixlist = r_server.get("matrix1")
  File "build\bdist.win32\egg\redis\client.py", line 705, in get
  File "build\bdist.win32\egg\redis\client.py", line 461, in execute_command
  File "build\bdist.win32\egg\redis\client.py", line 471, in parse_response
  File "build\bdist.win32\egg\redis\connection.py", line 349, in read_response
redis.exceptions.ResponseError: Operation against a key holding the wrong kind o
f value


import redis
from sympy import *
from sympy import Matrix
from sympy.abc import x, y, z, f, a, b
from sympy import *

r_server = redis.Redis("localhost")

f = Symbol('f')
x = Symbol('x')
y = Symbol('y')
z = Symbol('z')
varlist = [x,y,z,a,b]

A = Matrix([[1,0],[0,1]])
B = Matrix([[2,0],[0,5]])

r_server.sadd("matrix1", A)
r_server.sadd("matrix1", B)

matrixlist = r_server.get("matrix1")


From jobmattcon at gmail.com  Mon Mar 17 01:02:56 2014
From: jobmattcon at gmail.com (jobmattcon at gmail.com)
Date: Sun, 16 Mar 2014 22:02:56 -0700 (PDT)
Subject: pkg_resources.DistributionNotFound: hiredis
Message-ID: <d4d6f035-3f11-4446-97a7-db660b3fb16f@googlegroups.com>

http://heynemann.github.io/r3/

C:\heynemann-r3-cc6b4eb\build\lib\r3\app>r3-app --red
is-port=6379 --redis-pass=r3 -c config.py
Traceback (most recent call last):
  File "C:\Python27\Scripts\r3-app-script.py", line 5, in <module>
    from pkg_resources import load_entry_point
  File "C:\Python27\lib\site-packages\pkg_resources.py", line 2709, in <module>
    working_set.require(__requires__)
  File "C:\Python27\lib\site-packages\pkg_resources.py", line 664, in require
    needed = self.resolve(parse_requirements(requirements))
  File "C:\Python27\lib\site-packages\pkg_resources.py", line 567, in resolve
    raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: hiredis


[5700] 17 Mar 11:31:43.819 # Warning: no config file specified, using the defaul
t config. In order to specify a config file use C:\Users\martin.lee\Downloads\re
dis-2.6\bin\release\redis-server.exe /path/to/redis.conf
[5700] 17 Mar 11:31:43.828 # Warning: 32 bit instance detected but no memory lim
it set. Setting 3 GB maxmemory limit with 'noeviction' policy now.
                _._
           _.-``__ ''-._
      _.-``    `.  `_.  ''-._           Redis 2.6.12 (00000000/0) 32 bit
  .-`` .-```.  ```\/    _.,_ ''-._
 (    '      ,       .-`  | `,    )     Running in stand alone mode
 |`-._`-...-` __...-.``-._|'` _.-'|     Port: 6379
 |    `-._   `._    /     _.-'    |     PID: 5700
  `-._    `-._  `-./  _.-'    _.-'
 |`-._`-._    `-.__.-'    _.-'_.-'|
 |    `-._`-._        _.-'_.-'    |           http://redis.io
  `-._    `-._`-.__.-'_.-'    _.-'
 |`-._`-._    `-.__.-'    _.-'_.-'|
 |    `-._`-._        _.-'_.-'    |
  `-._    `-._`-.__.-'_.-'    _.-'
      `-._    `-.__.-'    _.-'
          `-._        _.-'
              `-.__.-'

[5700] 17 Mar 11:31:43.829 # Server started, Redis version 2.6.12
[5700] 17 Mar 11:31:43.829 * The server is now ready to accept connections on po


From ben+python at benfinney.id.au  Mon Mar 17 01:09:32 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 17 Mar 2014 16:09:32 +1100
Subject: pkg_resources.DistributionNotFound: hiredis
References: <d4d6f035-3f11-4446-97a7-db660b3fb16f@googlegroups.com>
Message-ID: <85txaxpg1f.fsf@benfinney.id.au>

jobmattcon at gmail.com writes:

> [a dump of text terminal output]

Did you have something to say about this? Perhaps a question, with
details of what you're expecting and what happened instead?

-- 
 \     ?Men never do evil so completely and cheerfully as when they do |
  `\        it from religious conviction.? ?Blaise Pascal (1623?1662), |
_o__)                                                   Pens?es, #894. |
Ben Finney



From jobmattcon at gmail.com  Mon Mar 17 01:35:54 2014
From: jobmattcon at gmail.com (jobmattcon at gmail.com)
Date: Sun, 16 Mar 2014 22:35:54 -0700 (PDT)
Subject: pkg_resources.DistributionNotFound: hiredis
In-Reply-To: <mailman.8176.1395032987.18130.python-list@python.org>
References: <d4d6f035-3f11-4446-97a7-db660b3fb16f@googlegroups.com>
 <mailman.8176.1395032987.18130.python-list@python.org>
Message-ID: <1e8a6c87-d635-4d3c-944f-8bb7f0d7458e@googlegroups.com>

first time run command to start r3, it has already got error
r3-app --redis-port=6379 --redis-pass=r3 -c config.py 

On Monday, March 17, 2014 1:09:32 PM UTC+8, Ben Finney wrote:
> writes:
> 
> 
> 
> > [a dump of text terminal output]
> 
> 
> 
> Did you have something to say about this? Perhaps a question, with
> 
> details of what you're expecting and what happened instead?
> 
> 
> 
> -- 
> 
>  \     "Men never do evil so completely and cheerfully as when they do |
> 
>   `\        it from religious conviction." --Blaise Pascal (1623-1662), |
> 
> _o__)                                                   Pens?es, #894. |
> 
> Ben Finney


From ben+python at benfinney.id.au  Mon Mar 17 02:04:06 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 17 Mar 2014 17:04:06 +1100
Subject: pkg_resources.DistributionNotFound: hiredis
References: <d4d6f035-3f11-4446-97a7-db660b3fb16f@googlegroups.com>
 <mailman.8176.1395032987.18130.python-list@python.org>
 <1e8a6c87-d635-4d3c-944f-8bb7f0d7458e@googlegroups.com>
Message-ID: <85ppllpdih.fsf@benfinney.id.au>

jobmattcon at gmail.com writes:

> first time run command to start r3, it has already got error
> r3-app --redis-port=6379 --redis-pass=r3 -c config.py 

First: please don't top-post; Instead, use the normal interleaved
posting style to make it easier to follow the conversation
<URL:https://en.wikipedia.org/wiki/Posting_style#Interleaved_style>.

Second: I don't have any idea what you're referring to, and your
messages give no explanation. Is this a question about Python, or some
specific tool, or some library, or what?

What are you trying to do (and please say it in terms that means we can
try to reproduce the problem), and what are you seeing instead, and how
does that differ from what you expect?

-- 
 \       ?The best is the enemy of the good.? ?Voltaire, _Dictionnaire |
  `\                                                    Philosophique_ |
_o__)                                                                  |
Ben Finney



From jobmattcon at gmail.com  Mon Mar 17 02:10:29 2014
From: jobmattcon at gmail.com (jobmattcon at gmail.com)
Date: Sun, 16 Mar 2014 23:10:29 -0700 (PDT)
Subject: pkg_resources.DistributionNotFound: hiredis
In-Reply-To: <mailman.8177.1395036261.18130.python-list@python.org>
References: <d4d6f035-3f11-4446-97a7-db660b3fb16f@googlegroups.com>
 <mailman.8176.1395032987.18130.python-list@python.org>
 <1e8a6c87-d635-4d3c-944f-8bb7f0d7458e@googlegroups.com>
 <mailman.8177.1395036261.18130.python-list@python.org>
Message-ID: <cda5459c-13ae-42a4-ac3a-1e83e7abcd25@googlegroups.com>

this is a specific tool related with python

http://heynemann.github.io/r3/

i am trying to do a simple example like the diagram in the web page 
describe and then use with sympy to massive generate functions and plot and print into a directory



On Monday, March 17, 2014 2:04:06 PM UTC+8, Ben Finney wrote:
>  writes:
> 
> 
> 
> > first time run command to start r3, it has already got error
> 
> > r3-app --redis-port=6379 --redis-pass=r3 -c config.py 
> 
> 
> 
> First: please don't top-post; Instead, use the normal interleaved
> 
> posting style to make it easier to follow the conversation
> 
> <URL:https://en.wikipedia.org/wiki/Posting_style#Interleaved_style>.
> 
> 
> 
> Second: I don't have any idea what you're referring to, and your
> 
> messages give no explanation. Is this a question about Python, or some
> 
> specific tool, or some library, or what?
> 
> 
> 
> What are you trying to do (and please say it in terms that means we can
> 
> try to reproduce the problem), and what are you seeing instead, and how
> 
> does that differ from what you expect?
> 
> 
> 
> -- 
> 
>  \       "The best is the enemy of the good." --Voltaire, _Dictionnaire |
> 
>   `\                                                    Philosophique_ |
> 
> _o__)                                                                  |
> 
> Ben Finney



From larry at hastings.org  Mon Mar 17 02:29:55 2014
From: larry at hastings.org (Larry Hastings)
Date: Sun, 16 Mar 2014 23:29:55 -0700
Subject: [RELEASED] Python 3.4.0
Message-ID: <53269663.9050408@hastings.org>


On behalf of the Python development team, I'm thrilled to announce
the official release of Python 3.4.


Python 3.4 includes a range of improvements of the 3.x series, including
hundreds of small improvements and bug fixes.  Major new features and
changes in the 3.4 release series include:

* PEP 428, a "pathlib" module providing object-oriented filesystem paths
* PEP 435, a standardized "enum" module
* PEP 436, a build enhancement that will help generate introspection
            information for builtins
* PEP 442, improved semantics for object finalization
* PEP 443, adding single-dispatch generic functions to the standard library
* PEP 445, a new C API for implementing custom memory allocators
* PEP 446, changing file descriptors to not be inherited by default
            in subprocesses
* PEP 450, a new "statistics" module
* PEP 451, standardizing module metadata for Python's module import system
* PEP 453, a bundled installer for the *pip* package manager
* PEP 454, a new "tracemalloc" module for tracing Python memory allocations
* PEP 456, a new hash algorithm for Python strings and binary data
* PEP 3154, a new and improved protocol for pickled objects
* PEP 3156, a new "asyncio" module, a new framework for asynchronous I/O


To download Python 3.4.0 visit:

     http://www.python.org/download/releases/3.4.0/


This is a production release.  Please report any issues you notice to:

      http://bugs.python.org/


Enjoy!


--
Larry Hastings, Release Manager
larry at hastings.org
(on behalf of the entire python-dev team and 3.4's contributors)


From rosuav at gmail.com  Mon Mar 17 02:46:29 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 17 Mar 2014 17:46:29 +1100
Subject: pkg_resources.DistributionNotFound: hiredis
In-Reply-To: <cda5459c-13ae-42a4-ac3a-1e83e7abcd25@googlegroups.com>
References: <d4d6f035-3f11-4446-97a7-db660b3fb16f@googlegroups.com>
 <mailman.8176.1395032987.18130.python-list@python.org>
 <1e8a6c87-d635-4d3c-944f-8bb7f0d7458e@googlegroups.com>
 <mailman.8177.1395036261.18130.python-list@python.org>
 <cda5459c-13ae-42a4-ac3a-1e83e7abcd25@googlegroups.com>
Message-ID: <CAPTjJmodB=BC9D=MU=eNe+gbfoC8j6u-oMPsqtx3UJGzwWJaGg@mail.gmail.com>

On Mon, Mar 17, 2014 at 5:10 PM,  <jobmattcon at gmail.com> wrote:
> this is a specific tool related with python
>
> http://heynemann.github.io/r3/
>
> i am trying to do a simple example like the diagram in the web page
> describe and then use with sympy to massive generate functions and plot and print into a directory

1) You've already been asked not to top-post. Please, read the
Wikipedia page Ben linked you to.

2) If you put no effort into your question, why should we put effort
into the answer?

3) You're asking about a particular program. Unless you can show that
the problem you're having is specific to Python, you'll probably do
better to ask the author of that program. Look around and see if s/he
has a recommended means of getting assistance - maybe a mailing list.

4) You still haven't explained your problem at all. While we might be
flattered at the implication that our skills are so great that we're
psychic, we're more likely to be frustrated by the utter lack of
information.

Please read this: http://www.catb.org/~esr/faqs/smart-questions.html

ChrisA


From sontek at gmail.com  Mon Mar 17 03:27:56 2014
From: sontek at gmail.com (sontek at gmail.com)
Date: Mon, 17 Mar 2014 00:27:56 -0700 (PDT)
Subject: asyncio libraries?
Message-ID: <55cac1b6-5aaa-43c8-9840-a7b576f5efed@googlegroups.com>

I'm a little late to the party, but now that Python 3.4 is out and asyncio is ready for use I started reading things like:

https://glyph.twistedmatrix.com/2014/02/unyielding.html

Which explains why the asyncio approach is the future and all the bullet points in that article make a lot of sense.

But my question now is if Python core developers are going to be releasing libraries to help working with things like databases, http requests, etc and all the reasons you may want asyncio?

Currently gevent is what I use most often because most libraries I use these days are already "greened" and I think asyncio needs something similar. Either extensions to popular things like psycopg2, pylibmc (or any memcached library), and urllib3 for example.

I've seen libraries like this: https://github.com/fafhrd91/psycotulip popping up but I would love to see some "blessed" libraries or even more documentation for common use cases and how someone could move to asyncio.

What about webservers?  Are there any decent webservers being built on top of asyncio instead of gevent, twisted, or tornado?


Thanks,
John


From steve at pearwood.info  Mon Mar 17 03:47:53 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 17 Mar 2014 07:47:53 GMT
Subject: pkg_resources.DistributionNotFound: hiredis
References: <d4d6f035-3f11-4446-97a7-db660b3fb16f@googlegroups.com>
 <mailman.8176.1395032987.18130.python-list@python.org>
 <1e8a6c87-d635-4d3c-944f-8bb7f0d7458e@googlegroups.com>
 <mailman.8177.1395036261.18130.python-list@python.org>
 <cda5459c-13ae-42a4-ac3a-1e83e7abcd25@googlegroups.com>
Message-ID: <5326a8a8$0$2923$c3e8da3$76491128@news.astraweb.com>

On Sun, 16 Mar 2014 23:10:29 -0700, jobmattcon wrote:

> this is a specific tool related with python
> 
> http://heynemann.github.io/r3/
> 
> i am trying to do a simple example like the diagram in the web page
> describe and then use with sympy to massive generate functions and plot
> and print into a directory

I'm afraid that unless you can identify where the problem lies, we 
probably won't be able to help you.

I've used sympy, but I haven't used r3 or redis. Can you confirm:


- is redis is working outside of Python?

- can you get sympy working without r3?

- have you installed r3 successfully? how do you know?

- can you demonstrate the SIMPLEST possible piece of 
  code that shows the failure?


Reading this website may help. Although it is written for Java, the same 
principles apply to Python:

http://www.sscce.org/

Good luck!

And by the way, although most of us will try to be tolerant towards minor 
breaches of etiquette, we do prefer interleaved posting like this:

    > Question blah blah?

    Answer.

    > Another question?

    Further answers.


rather than top posting:

    Answer.
    Further answers.

    > Question blah blah blah?
    > Another question?


See here for more details:

http://en.wikipedia.org/wiki/Posting_style


Thanks in advance,



-- 
Steven


From list at qtrac.plus.com  Mon Mar 17 04:44:23 2014
From: list at qtrac.plus.com (Mark Summerfield)
Date: Mon, 17 Mar 2014 01:44:23 -0700 (PDT)
Subject: Correct idiom for determining path when frozen in 3.4
Message-ID: <8a0ca549-7bce-4210-8f9e-3465a769fc3c@googlegroups.com>

Hi,

What is the correct idiom for getting the path to a top-level module in 3.3 and 3.4 when the module might be frozen?

At the moment I'm using this:

    if getattr(sys, "frozen", False):
        path = os.path.dirname(sys.executable)
    else:
        path = os.path.dirname(__file__)

Thanks!


From troll at bitch.invalid  Mon Mar 17 04:50:19 2014
From: troll at bitch.invalid (ASSODON)
Date: Mon, 17 Mar 2014 04:50:19 -0400
Subject: HOLY SH*T! HUMANS ORIGINATED IN THE DEVONIAN
Message-ID: <MPG.2d90815744d89924989689@news.eternal-september.org>

=======================
>BREAKING NEWSSSSSSSSS
=======================
>
RICHARD LEAKEY JUST DIED DUE TO HEART FAILURE!
>
THE REASONS DESCRIBED BY THE MEDICAL TEAM IS THAT HIS WORK WAS 
DISPROVEN, BY NONE OTHER THAN YOUR OWN BASTARD, THRINAXODON.
>
THIS CAUSED LEAKEY'S HEART TO EXPLODE!
>
THRINAXODON DANCED WITH JOY AS HE WAS GRANTED $600,000,000,000.000!
>
TO WASTE YOUR TIME EVEN FURTHER, CHECK OUT THESE LINKS BELOW.
===========================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/threa
d/6f501c469c7af24f#


https://groups.google.com/group/sci.bio.paleontology/browse_thread/threa
d/3aad75c16afb0b82#


====================================

http://thrinaxodon.wordpress.com/

===================================

THRINAXODON ONLY HAD THIS TO SAY:

"I..I...I...Can't believe it. This completely disproved Darwinian
orthodoxy."

===================================

THE BASTARDS AT THE SMITHSONIAN, AND THE LEAKEY FOUNDATION ARE ERODING
WITH FEAR.

===========================
THESE ASSHOLES ARE GOING TO DIE:
THOMAS AQUINAS;
ALDOUS HUXLEY;
BOB CASANVOVA;
SkyEyes;
DAVID IAIN GRIEG;
MARK ISAAK;
JOHN HARSHAM;
RICHARD NORMAN;
DR. DOOLITTLE;
CHARLES DARWIN;
MARK HORTON;
ERIK SIMPSON;
HYPATIAB7;
PAUL J. GANS;
JILLERY;
WIKI TRIK;
THRINAXODON;
PETER NYIKOS;
RON OKIMOTO;
JOHN S. WILKINS
===========================

THRINAXODON WAS SCOURING ANOTHER DEVONIAN FOSSIL BED, AND FOUND A
HUMAN SKULL, AND A HUMAN FEMUR. HE ANALYSED THE FINDS, AND SAW THAT
THEY WERE NOT NORMAL ROCKS. THESE WERE FOSSILIZED BONES. THEY EVEN HAD
TOOTH MARKS ON THEM. SO, THRINAXODON BROUGHT THEM TO THE LEAKEY
FOUNDATION, THEY UTTERLY DISMISSED IT, AND SAID, "We want to keep
people thinking that humans evolved 2 Ma." THRINAXODON BROUGHT HIS
SWORD, AND SAID, "SCIENCE CORRECTS ITSELF." RICHARD LEAKEY SAID, "That
is a myth, for people to believe in science." THRINAXODON PLANS TO
BRING DOOM TO SCIENCE, ITSELF.

============================

THRINAXODON IS NOW ON REDDIT 



From ben+python at benfinney.id.au  Mon Mar 17 05:02:15 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 17 Mar 2014 20:02:15 +1100
Subject: Correct idiom for determining path when frozen in 3.4
References: <8a0ca549-7bce-4210-8f9e-3465a769fc3c@googlegroups.com>
Message-ID: <85ha6xp59k.fsf@benfinney.id.au>

Mark Summerfield <list at qtrac.plus.com> writes:

> What is the correct idiom for getting the path to a top-level module

I'm not sure I understand what this concept is. What do you mean by
?top-level module??

> in 3.3 and 3.4 when the module might be frozen?
>
> At the moment I'm using this:
>
>     if getattr(sys, "frozen", False):
>         path = os.path.dirname(sys.executable)
>     else:
>         path = os.path.dirname(__file__)

That looks okay. Does it work?

The code is readable and Pythonic as is. But I would suggest several
improvements::

    if getattr(sys, "frozen"):    # ?getattr? will return None by default

Also, why test for ?sys.frozen? when you're about to use
?sys.executable??

    if getattr(sys, "executable"):

Lastly, it's slightly more Pythonic to execute the normal path
unconditionally, and let it raise an exception if there's a problem::

    try:
        executable = sys.executable
    except AttributeError:
        executable = __file__
    path = os.path.dirname(executable)

-- 
 \     ?It is far better to grasp the universe as it really is than to |
  `\    persist in delusion, however satisfying and reassuring.? ?Carl |
_o__)                                                            Sagan |
Ben Finney



From jeanpierreda at gmail.com  Mon Mar 17 05:16:47 2014
From: jeanpierreda at gmail.com (Devin Jeanpierre)
Date: Mon, 17 Mar 2014 02:16:47 -0700
Subject: Correct idiom for determining path when frozen in 3.4
In-Reply-To: <85ha6xp59k.fsf@benfinney.id.au>
References: <8a0ca549-7bce-4210-8f9e-3465a769fc3c@googlegroups.com>
 <85ha6xp59k.fsf@benfinney.id.au>
Message-ID: <CABicbJK9tyNoiPMKZdLqYoebrsWXPet7YxWPUo4s7_j9P7NBkg@mail.gmail.com>

On Mon, Mar 17, 2014 at 2:02 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> Mark Summerfield <list at qtrac.plus.com> writes:
>     if getattr(sys, "frozen"):    # ?getattr? will return None by default

No it won't.

> Lastly, it's slightly more Pythonic to execute the normal path
> unconditionally, and let it raise an exception if there's a problem::
>
>     try:
>         executable = sys.executable
>     except AttributeError:
>         executable = __file__
>     path = os.path.dirname(executable)

Sure, but sys.executable always exists. sys.frozen doesn't, and the
existence or nonexistence is apparently meaningful; so your code does
something different than the original problem statement.

Also, if that weren't the case, I'd really replace that try-except
with getattr(sys, 'executable', __file__)

-- Devin


From ben+python at benfinney.id.au  Mon Mar 17 05:23:59 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 17 Mar 2014 20:23:59 +1100
Subject: Correct idiom for determining path when frozen in 3.4
References: <8a0ca549-7bce-4210-8f9e-3465a769fc3c@googlegroups.com>
 <85ha6xp59k.fsf@benfinney.id.au>
 <CABicbJK9tyNoiPMKZdLqYoebrsWXPet7YxWPUo4s7_j9P7NBkg@mail.gmail.com>
Message-ID: <85d2hlp49c.fsf@benfinney.id.au>

Devin Jeanpierre <jeanpierreda at gmail.com> writes:

> On Mon, Mar 17, 2014 at 2:02 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> > Mark Summerfield <list at qtrac.plus.com> writes:
> >     if getattr(sys, "frozen"):    # ?getattr? will return None by default
>
> No it won't.
> [?]
> Sure, but sys.executable always exists.

My apologies for posting untested code without making that clear. Thanks
to Devin for picking up my mistakes.

> > Lastly, it's slightly more Pythonic to execute the normal path
> > unconditionally, and let it raise an exception if there's a problem::
> >
> >     try:
> >         executable = sys.executable
> >     except AttributeError:
> >         executable = __file__
> >     path = os.path.dirname(executable)

> sys.frozen doesn't [necessarily exist], and the existence or
> nonexistence is apparently meaningful; so your code does something
> different than the original problem statement.

Right. I didn't understand why ?__file__? is a suitable substitute for
?sys.executable?; they're always (?) different values. So that probably
is what led to the confusion in the code behaviour.

I hope the Pythonic idioms are helpful to the original poster
nevertheless.

-- 
 \      ?Anyone who believes exponential growth can go on forever in a |
  `\        finite world is either a madman or an economist.? ?Kenneth |
_o__)                                                         Boulding |
Ben Finney



From oscar.j.benjamin at gmail.com  Mon Mar 17 05:52:55 2014
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Mon, 17 Mar 2014 09:52:55 +0000
Subject: Correct idiom for determining path when frozen in 3.4
In-Reply-To: <8a0ca549-7bce-4210-8f9e-3465a769fc3c@googlegroups.com>
References: <8a0ca549-7bce-4210-8f9e-3465a769fc3c@googlegroups.com>
Message-ID: <CAHVvXxS1OdtOLJ0780hZm1RWQ=yHr7FPL1NkCu6sL4eY4QzjSA@mail.gmail.com>

On 17 March 2014 08:44, Mark Summerfield <list at qtrac.plus.com> wrote:
> Hi,
>
> What is the correct idiom for getting the path to a top-level module in 3.3 and 3.4 when the module might be frozen?
>
> At the moment I'm using this:
>
>     if getattr(sys, "frozen", False):
>         path = os.path.dirname(sys.executable)
>     else:
>         path = os.path.dirname(__file__)

Why do you want to know this? Does pkgutil.get_data do what you want?

http://docs.python.org/3.3/library/pkgutil.html#pkgutil.get_data


Oscar


From laguna-mc at mail.com  Mon Mar 17 07:29:10 2014
From: laguna-mc at mail.com (Andrew Williams)
Date: Mon, 17 Mar 2014 07:29:10 -0400
Subject: Error when installing matplotlib-1.3. on Windows
Message-ID: <20140317112910.64790@gmx.com>

Note that I have Portable Python, installed on USB flash drive. When I tried run matplotlib installer, I got error:'Cannot install': "Python version 2.7 required, which was not found in the registry" 

----- Original Message -----
From: MRAB
Sent: 03/17/14 03:55 AM
To: python-list at python.org
Subject: Re: Error when installing matplotlib-1.3. on Windows

On 2014-03-17 01:20, laguna-mc at mail.com wrote: > I'm trying to install matplotlib from locally stored source archive file > (Portable Python 2.7 on Windows): > > pip install E:\matplotlib-1.3.1.win32-py2.7.exe > > Got error, below is log: > > > E:\Portable Python 2.7.5.1\App\Scripts\pip run on 03/17/14 03:10:16 > Exception: > Traceback (most recent call last): > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\basecommand.py", line 122, in main > status = self.run(options, args) > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\commands\install.py", line 257, in run > InstallRequirement.from_line(name, None)) > File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", > line 172, in from_line > return cls(req, comes_from, url=url, prereleases=prereleases) > File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", > line 70, in __init__ > req = pkg_resources.Requirement.parse(req) > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2606, > in parse > reqs = list(parse_requirements(s)) > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2544, > in parse_requirements > line, p, specs = scan_list(VERSION,LINE_END,line,p,(1,2),"version > spec") > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2512, > in scan_list > raise ValueError("Expected "+item_name+" in",line,"at",line[p:]) > ValueError: ('Expected version spec in', > 'E:\\matplotlib-1.3.1.win32-py2.7.exe', 'at', > ':\\matplotlib-1.3.1.win32-py2.7.exe') > > > What is the problem and how to solve it? > Judging by the name, I'd say that "matplotlib-1.3.1.win32-py2.7.exe" is an installer, so you just need to run it. -- https://mail.python.org/mailman/listinfo/python-list
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From frank at chagford.com  Mon Mar 17 09:06:33 2014
From: frank at chagford.com (Frank Millman)
Date: Mon, 17 Mar 2014 15:06:33 +0200
Subject: Question about Source Control
Message-ID: <lg6s09$irl$1@ger.gmane.org>

Hi all

I know I *should* be using a Source Control Management system, but at 
present I am not. I tried to set up Mercurial a couple of years ago, but I 
think I set it up wrongly, as I got myself confused and found it more of a 
hindrance than a help. Now I am ready to try again, but I want to avoid my 
earlier mistakes.

I understand the concept, and I understand the importance, so I do not need 
reminding of those. What I would like help with is the basic setup. I could 
subscribe to the Mercurial mailing list and ask there, but I am hoping for a 
kick-start here. Here is my setup.

All my source code resides on an old Linux server, which I switch on in the 
morning and switch off at night, but otherwise hardly ever look at. It uses 
'samba' to allow sharing with Windows, and 'nfs' to allow sharing with other 
Linux machines.

I need to test my program on Windows and on Linux, so I run it from both at 
various times. On Windows I have a 'mapped drive' pointing to the source 
code. On Linux I use a third machine, running a recent Fedora, using nfs to 
mount a directory pointing to the source code. Obviously each machine has 
its own version of Python installed.

I do my development on the Windows machine. I use TextPad, a simple text 
editor, which works fine for my purposes. It uses the mapped drive to point 
to the source code.

So where should I install the SCM, and how should I set it up so that I can 
access the latest version from any machine?

Any hints will be appreciated.

Frank Millman





From andriy.kornatskyy at live.com  Mon Mar 17 09:25:30 2014
From: andriy.kornatskyy at live.com (Andriy Kornatskyy)
Date: Mon, 17 Mar 2014 15:25:30 +0200
Subject: Question about Source Control
In-Reply-To: <lg6s09$irl$1@ger.gmane.org>
References: <lg6s09$irl$1@ger.gmane.org>
Message-ID: <BLU0-SMTP953C8572B5CA6374830E50917D0@phx.gbl>

Frank,

I would suggest start with an account on https://bitbucket.org. It supports private repositories so you should be good there.

From other hand you can setup own infrastructure for SCM, read more here:
http://mindref.blogspot.com/2013/10/how-to-manage-git-or-mercurial.html 

Thanks.

Andriy Kornatskyy

On Mar 17, 2014, at 3:06 PM, Frank Millman <frank at chagford.com> wrote:

> Hi all
> 
> I know I *should* be using a Source Control Management system, but at 
> present I am not. I tried to set up Mercurial a couple of years ago, but I 
> think I set it up wrongly, as I got myself confused and found it more of a 
> hindrance than a help. Now I am ready to try again, but I want to avoid my 
> earlier mistakes.
> 
> I understand the concept, and I understand the importance, so I do not need 
> reminding of those. What I would like help with is the basic setup. I could 
> subscribe to the Mercurial mailing list and ask there, but I am hoping for a 
> kick-start here. Here is my setup.
> 
> All my source code resides on an old Linux server, which I switch on in the 
> morning and switch off at night, but otherwise hardly ever look at. It uses 
> 'samba' to allow sharing with Windows, and 'nfs' to allow sharing with other 
> Linux machines.
> 
> I need to test my program on Windows and on Linux, so I run it from both at 
> various times. On Windows I have a 'mapped drive' pointing to the source 
> code. On Linux I use a third machine, running a recent Fedora, using nfs to 
> mount a directory pointing to the source code. Obviously each machine has 
> its own version of Python installed.
> 
> I do my development on the Windows machine. I use TextPad, a simple text 
> editor, which works fine for my purposes. It uses the mapped drive to point 
> to the source code.
> 
> So where should I install the SCM, and how should I set it up so that I can 
> access the latest version from any machine?
> 
> Any hints will be appreciated.
> 
> Frank Millman
> 
> 
> 
> -- 
> https://mail.python.org/mailman/listinfo/python-list



From jprashanthan at gmail.com  Mon Mar 17 03:06:42 2014
From: jprashanthan at gmail.com (J Prashanthan)
Date: Mon, 17 Mar 2014 12:36:42 +0530
Subject: No subject
Message-ID: <CAGDTmXGpDYAVsfYNa=9O8On4ZSb7MuKZNZdAFwrens-C1Op_UA@mail.gmail.com>

i am doing my masters currently and im stuck up with my final project. As i
was interested in learning a new language i opted to do my final project in
python. im currently working on building an unit tester for multithreaded
code. Due to various reasons i got stuck with my project. basically my lack
of knowledge in python and i have none to help me with it. i have no idea
what to do with my project . and my deadline is in another 1 week . I have
completed working on the atomicity violation finder .
Finding Atomicity-Violation Bugs through Unserializable Interleaving
Testing by
Shan Lu, Soyeon Park, and Yuanyuan Zhou, Member, IEEE. This is my base
paper . can anyone please help me with it. if anyone has a working code
please mail me.
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From skip at pobox.com  Mon Mar 17 10:08:13 2014
From: skip at pobox.com (Skip Montanaro)
Date: Mon, 17 Mar 2014 09:08:13 -0500
Subject: Looking for someone who can build a 64-bit version of SpamBayes
 installer for Windows
In-Reply-To: <CANc-5UxkDZNkKPDRd5zu-uMewbwQ_QZFZejhh-LheCPArbYsJQ@mail.gmail.com>
References: <CANc-5UxkDZNkKPDRd5zu-uMewbwQ_QZFZejhh-LheCPArbYsJQ@mail.gmail.com>
Message-ID: <CANc-5UwMeoSKT=qkJTU=jtVCxDv6BnwxmEHb8ZLmamsStkdOSA@mail.gmail.com>

> .... As more and
> more Windows users have moved to 64-bit versions of Windows and
> Outlook, we've had more and more reports of failures.
>
> I think all that's necessary (speaking as someone who knows nothing
> about Windows) is for someone to build a 64-bit version of the
> SpamBayes installer for Windows....
>
> Anybody available to help?

Still looking for someone to help building a 64-bit installer for
SpamBayes on Windows. Anyone? Any idea where else to plead for help?

Skip


From breamoreboy at yahoo.co.uk  Mon Mar 17 10:39:09 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 17 Mar 2014 14:39:09 +0000
Subject: Looking for someone who can build a 64-bit version of SpamBayes
 installer for Windows
In-Reply-To: <CANc-5UwMeoSKT=qkJTU=jtVCxDv6BnwxmEHb8ZLmamsStkdOSA@mail.gmail.com>
References: <CANc-5UxkDZNkKPDRd5zu-uMewbwQ_QZFZejhh-LheCPArbYsJQ@mail.gmail.com>
 <CANc-5UwMeoSKT=qkJTU=jtVCxDv6BnwxmEHb8ZLmamsStkdOSA@mail.gmail.com>
Message-ID: <lg71dv$pnv$1@ger.gmane.org>

On 17/03/2014 14:08, Skip Montanaro wrote:
>> .... As more and
>> more Windows users have moved to 64-bit versions of Windows and
>> Outlook, we've had more and more reports of failures.
>>
>> I think all that's necessary (speaking as someone who knows nothing
>> about Windows) is for someone to build a 64-bit version of the
>> SpamBayes installer for Windows....
>>
>> Anybody available to help?
>
> Still looking for someone to help building a 64-bit installer for
> SpamBayes on Windows. Anyone? Any idea where else to plead for help?
>
> Skip
>

https://mail.python.org/mailman/listinfo/python-win32 which is gated to 
gmane.comp.python.windows

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Mon Mar 17 10:53:44 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 01:53:44 +1100
Subject: Question about Source Control
In-Reply-To: <lg6s09$irl$1@ger.gmane.org>
References: <lg6s09$irl$1@ger.gmane.org>
Message-ID: <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>

On Tue, Mar 18, 2014 at 12:06 AM, Frank Millman <frank at chagford.com> wrote:
> All my source code resides on an old Linux server, which I switch on in the
> morning and switch off at night, but otherwise hardly ever look at. It uses
> 'samba' to allow sharing with Windows, and 'nfs' to allow sharing with other
> Linux machines.
>
> I need to test my program on Windows and on Linux, so I run it from both at
> various times. On Windows I have a 'mapped drive' pointing to the source
> code. On Linux I use a third machine, running a recent Fedora, using nfs to
> mount a directory pointing to the source code. Obviously each machine has
> its own version of Python installed.
>
> I do my development on the Windows machine. I use TextPad, a simple text
> editor, which works fine for my purposes. It uses the mapped drive to point
> to the source code.
>
> So where should I install the SCM, and how should I set it up so that I can
> access the latest version from any machine?

First off: You can save yourself a huge amount of trouble now! Modern
source control systems are distributed (DVCS - Distributed Version
Control System), which means that you have a much simpler setup: every
machine that uses it has a full clone of the repository.

By the sound of it, you don't have any history at the moment, so I'll
assume you just start using either git or hg from where you are. The
first thing to do is to get a local copy of the current source tree.
I'd start with a Linux system, because everything seems to be easier
there...

$ cp -r /mnt/samba/whatever/some_project_name .

Then you just 'cd' into the project directory (which can be anywhere
local - I tend to have a whole pile of them directly in my home
directory, or the root directory on Windows, but you can put them
anywhere; on my Hackintosh, I use the Documents directory so I can
find it more easily), and type either:

$ git init
$ git add .
$ git commit -m'Initial commit'

or

$ hg init
$ hg add .
$ hg commit -m'Initial commit'

Voila! You now have a repository tracking all your current source code
for that project. Then you just set yourself up to pull and push
somewhere. The easiest way to do that is to designate somewhere as the
central repository and always push changes to there and pull changes
from there; that's not strictly necessary, but I do recommend it.
Andriy recommends bitbucket; I like github, but that (as the name
implies) requires that you use git rather than Mercurial. (I also find
that git is rather faster than hg at most tasks. On the flip side, hg
is said to be a lot easier to set up on Windows than git is. I've
never used hg on Windows, so I can't say, but git on Windows isn't
quite as easy as could be desired.) You can also set up your own local
server very easily - a good plan if you're moving big binaries around
(not usually what you'd call "source code", but perfectly acceptable;
I recently ripped out our shared folder document repository and
replaced it with git-managed files) or working with something highly
sensitive. But for an open-source project, it's easiest to host it
"out there" somewhere, and let someone else do the work.

After that, it's simply a matter of going through the "quick start"
tutorial for your preferred SCM and host, which will help you get
started with authentication, push/pull commands, etc etc etc. Source
control is something to get your head around, but once you've done
that (which you might already have done for the sake of some open
source project), everything else becomes easy. Shared folders are easy
to explain to someone ("you can access this from everywhere!"), but
git or hg gives you ever so much more for no extra effort ("not only
can you keep track of your files, you can go back in time to see
what's happened, keep track of different branches of development,
share it all with the world, get suggestions from the world...").
Start thinking in terms of "my files are in this repository" rather
than "my files are on this server", and have lots of clones of that
repository, all acting as peers. Life's way better that way :)

ChrisA


From rosuav at gmail.com  Mon Mar 17 11:01:23 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 02:01:23 +1100
Subject: No subject
In-Reply-To: <CAGDTmXGpDYAVsfYNa=9O8On4ZSb7MuKZNZdAFwrens-C1Op_UA@mail.gmail.com>
References: <CAGDTmXGpDYAVsfYNa=9O8On4ZSb7MuKZNZdAFwrens-C1Op_UA@mail.gmail.com>
Message-ID: <CAPTjJmot_jK=hV0eMZGgheZffYgvaCMaAYoAoBJqP0+4M8NJEw@mail.gmail.com>

On Mon, Mar 17, 2014 at 6:06 PM, J Prashanthan <jprashanthan at gmail.com> wrote:
> i am doing my masters currently and im stuck up with my final project. As i
> was interested in learning a new language i opted to do my final project in
> python. im currently working on building an unit tester for multithreaded
> code. Due to various reasons i got stuck with my project. basically my lack
> of knowledge in python and i have none to help me with it. i have no idea
> what to do with my project . and my deadline is in another 1 week . I have
> completed working on the atomicity violation finder .
> Finding Atomicity-Violation Bugs through Unserializable Interleaving Testing
> by
> Shan Lu, Soyeon Park, and Yuanyuan Zhou, Member, IEEE. This is my base paper
> . can anyone please help me with it. if anyone has a working code please
> mail me.

Almost certainly nobody here has working code that they're willing to
simply give you. Is your final project expected to be more than a
week's work? If so, I think you're a bit stuck - at least as regards
the deadline. But if you have a good idea of how to write code (in
some other language than Python), and if you have a thorough set of
notes of what you're trying to accomplish (in pseudo-code, or at least
your native language - for me that would be English), then you might
be able to translate it all into working Python code fairly
efficiently.

A week is, I'm afraid, not very long for a large project. But with a
good language, you can do an amazing amount of work in a short time;
and Python is a very good language. I recently knocked together most
of a game engine inside 24 hours (not in Python but in a similar
language); you might well be able to go from nil to running before
your time is up. But it's going to take a lot of work, and you're
going to need to start by getting broad familiarity with Python. So
start here:

http://docs.python.org/3/tutorial/

ChrisA


From breamoreboy at yahoo.co.uk  Mon Mar 17 11:11:22 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 17 Mar 2014 15:11:22 +0000
Subject: Looking for someone who can build a 64-bit version of SpamBayes
 installer for Windows
In-Reply-To: <lg71dv$pnv$1@ger.gmane.org>
References: <CANc-5UxkDZNkKPDRd5zu-uMewbwQ_QZFZejhh-LheCPArbYsJQ@mail.gmail.com>
 <CANc-5UwMeoSKT=qkJTU=jtVCxDv6BnwxmEHb8ZLmamsStkdOSA@mail.gmail.com>
 <lg71dv$pnv$1@ger.gmane.org>
Message-ID: <lg73ac$jmv$1@ger.gmane.org>

On 17/03/2014 14:39, Mark Lawrence wrote:
> On 17/03/2014 14:08, Skip Montanaro wrote:
>>> .... As more and
>>> more Windows users have moved to 64-bit versions of Windows and
>>> Outlook, we've had more and more reports of failures.
>>>
>>> I think all that's necessary (speaking as someone who knows nothing
>>> about Windows) is for someone to build a 64-bit version of the
>>> SpamBayes installer for Windows....
>>>
>>> Anybody available to help?
>>
>> Still looking for someone to help building a 64-bit installer for
>> SpamBayes on Windows. Anyone? Any idea where else to plead for help?
>>
>> Skip
>>
>
> https://mail.python.org/mailman/listinfo/python-win32 which is gated to
> gmane.comp.python.windows
>

Or cgohlke at uci.edu as he maintains this "Unofficial Windows Binaries 
for Python Extension Packages" here 
http://www.lfd.uci.edu/~gohlke/pythonlibs/

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From list at qtrac.plus.com  Mon Mar 17 11:31:44 2014
From: list at qtrac.plus.com (Mark Summerfield)
Date: Mon, 17 Mar 2014 08:31:44 -0700 (PDT)
Subject: Correct idiom for determining path when frozen in 3.4
In-Reply-To: <8a0ca549-7bce-4210-8f9e-3465a769fc3c@googlegroups.com>
References: <8a0ca549-7bce-4210-8f9e-3465a769fc3c@googlegroups.com>
Message-ID: <fa3d42dc-fcac-460f-96a7-890513d4e638@googlegroups.com>

On Monday, 17 March 2014 08:44:23 UTC, Mark Summerfield  wrote:
> Hi,
> 
> 
> 
> What is the correct idiom for getting the path to a top-level module in 3.3 and 3.4 when the module might be frozen?
> 
> 
> 
> At the moment I'm using this:
> 
> 
> 
>     if getattr(sys, "frozen", False):
> 
>         path = os.path.dirname(sys.executable)
> 
>     else:
> 
>         path = os.path.dirname(__file__)
> 
> 
> 
> Thanks!

My code was adapted from this:
http://cx-freeze.readthedocs.org/en/latest/faq.html#using-data-files

When you freeze a Python program with cx_Freeze, sys.freeze exists; but otherwise it doesn't.

I develop some programs which I freeze for distribution but during development I test them as-is so I need to be able to distinguish.

Also, from 3.4, __file__ won't exist in frozen modules:
http://docs.python.org/3.4/whatsnew/3.4.html#changes-in-the-python-api

Thanks for your thoughtful replies.


From skip at pobox.com  Mon Mar 17 12:03:03 2014
From: skip at pobox.com (Skip Montanaro)
Date: Mon, 17 Mar 2014 11:03:03 -0500
Subject: Looking for someone who can build a 64-bit version of SpamBayes
 installer for Windows
In-Reply-To: <lg73ac$jmv$1@ger.gmane.org>
References: <CANc-5UxkDZNkKPDRd5zu-uMewbwQ_QZFZejhh-LheCPArbYsJQ@mail.gmail.com>
 <CANc-5UwMeoSKT=qkJTU=jtVCxDv6BnwxmEHb8ZLmamsStkdOSA@mail.gmail.com>
 <lg71dv$pnv$1@ger.gmane.org> <lg73ac$jmv$1@ger.gmane.org>
Message-ID: <CANc-5Uz01qu5jxKpCJdJ9-RzDnw2ng3bADiBaNZOYVRfHVVgAQ@mail.gmail.com>

On Mon, Mar 17, 2014 at 10:11 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>> https://mail.python.org/mailman/listinfo/python-win32 which is gated to
>> gmane.comp.python.windows
>>
>
> Or cgohlke at uci.edu as he maintains this "Unofficial Windows Binaries for
> Python Extension Packages" here http://www.lfd.uci.edu/~gohlke/pythonlibs/

Thanks for the pointers, Mark. I'll get in touch with Chris Gohlke.
I'm pretty sure I've asked on the python-win32 list before, but I'll
check there again.

Skip


From zachary.ware+pylist at gmail.com  Mon Mar 17 12:03:10 2014
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Mon, 17 Mar 2014 11:03:10 -0500
Subject: Correct idiom for determining path when frozen in 3.4
In-Reply-To: <fa3d42dc-fcac-460f-96a7-890513d4e638@googlegroups.com>
References: <8a0ca549-7bce-4210-8f9e-3465a769fc3c@googlegroups.com>
 <fa3d42dc-fcac-460f-96a7-890513d4e638@googlegroups.com>
Message-ID: <CAKJDb-PRuVPxsCu_DF_6EhAVTwG-99SmD06uZr8gQLFz2u0U1w@mail.gmail.com>

On Mon, Mar 17, 2014 at 10:31 AM, Mark Summerfield <list at qtrac.plus.com> wrote:
> My code was adapted from this:
> http://cx-freeze.readthedocs.org/en/latest/faq.html#using-data-files
>
> When you freeze a Python program with cx_Freeze, sys.freeze exists; but otherwise it doesn't.
>
> I develop some programs which I freeze for distribution but during development I test them as-is so I need to be able to distinguish.
>
> Also, from 3.4, __file__ won't exist in frozen modules:
> http://docs.python.org/3.4/whatsnew/3.4.html#changes-in-the-python-api

Have a look at __spec__, specifically __spec__.origin:

>>> import sys
>>> _fi = sys.modules['_frozen_importlib']
>>> _fi
<module '_frozen_importlib' (frozen)>
>>> _fi.__spec__
ModuleSpec(name='_frozen_importlib', loader=<class
'_frozen_importlib.FrozenImporter'>, origin='<frozen>')
>>> _fi.__spec__.origin
'<frozen>'

I've not looked up in the importlib docs to confirm, but that should
mean that frozen modules should have a __spec__.origin that contains
"frozen".

HTH,
-- 
Zach


From harrismh777 at gmail.com  Mon Mar 17 12:18:56 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 17 Mar 2014 11:18:56 -0500
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
Message-ID: <lg779d$5f4$2@speranza.aioe.org>

On 3/15/14 11:26 AM, Jayanth Koushik wrote:

This is a very interesting philosophical question, one which I am 
surprised no one has answered; although, I think the reason for that 
might be entirely obvious.

You actually answered your own question, as you were asking it. If the 
doc says "whatever you do, don't push the purple button," well, leave 
the purple button alone.      :)   (I don't know, push it if you want)

If you monitor the PEP process, or have ever taken part in python-ideas, 
or python-dev (either directly, or just lurking) you will notice that 
python is developed through a very interesting active committee process 
(that is really something phenomenal; cool community).

How should one spell a complex number? Should we use i or j ? Should the 
imaginary part be set off somehow?  Should literals be parsed 
differently (or consistently) with correctly formed strings?  Who knows, 
beats me.

consider:
 >>> complex( 3   +  2   j)
SyntaxError: invalid syntax
 >>> complex( 3   +2j  )
(3+2j)
 >>>
I don't know... you tell me.

 >>> complex('3+2j')
(3+2j)
 >>> complex('3 +2j')
Traceback (most recent call last):
   File "<pyshell#17>", line 1, in <module>
     complex('3 +2j')
ValueError: complex() arg is a malformed string
 >>>

Again, beats me.  I just don't know.

But I do know that the spelling book says, Do it this way: 
complex('3+2j').

Seems simple enough.


Philosophically, I tend to think about it this way. A complex number is 
like any other number. I would not form a PI string like this> ' 3 .14 1 
5 9265 3 . . .'   I would rather see it formed like so, '3.1415926535'

This  '3 + 2j'  is not a number, its an algebraic sum.

This  '3+2j'  is a complex number.  Ok, maybe not, but its closer to 
what we expect (I'm sorry, but I like  i  instead  of  j  )

Also, philosophically, C ignores white space;  python does not.

I agree with this now; before I did not. White space is just as much a 
part of how interpretation occurs, within symbol processing/parsing. 
Some choices are arbitrary, some are community concurrence (PEPs), some 
are philosophical, and most are just convenient intuition.

My Greek professor used to say, "there is no 'why' in Greek".

Python is similar.

Cheers



From harrismh777 at gmail.com  Mon Mar 17 12:42:40 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 17 Mar 2014 11:42:40 -0500
Subject: test
References: <lg2geg$48n$1@speranza.aioe.org>
 <mailman.8158.1394934532.18130.python-list@python.org>
 <lg36h6$hb0$1@speranza.aioe.org>
 <mailman.8166.1394964771.18130.python-list@python.org>
Message-ID: <lg78lt$9p9$1@speranza.aioe.org>

On 3/16/14 5:07 AM, Chris ?Kwpolska? Warrick wrote:
> Why not use the mailing list instead?  It?s a much easier way to
> access this place.

I prefer to 'pull' rather than receive the 'push'.

The newsreader idea is better because threading works better, and
because the interface is simpler. I don't know, just preference
I guess.

I am active on several mailing lists also; they only have list
servers (not news Usenet server). The Usenet news reader concept
must be fading away, and many isp(s) are not providing the nntp
post service these days (Charter stopped it in late 2011).

There are still several free post servers out there that do not
require registration (some are free but do require registration).

What are most active pythoniacs doing with this these days?

(beats me)



From rymg19 at gmail.com  Mon Mar 17 12:57:08 2014
From: rymg19 at gmail.com (Ryan Gonzalez)
Date: Mon, 17 Mar 2014 11:57:08 -0500
Subject: [Python-Dev] [RELEASED] Python 3.4.0
In-Reply-To: <53269663.9050408@hastings.org>
References: <53269663.9050408@hastings.org>
Message-ID: <CAO41-mPV0GcV9EEPjv_DDJAOWL3O7Q6QV1ET5EN=wp-64Rwqrg@mail.gmail.com>

YES!!! +1 to the authors of the statistics and pathlib modules.


On Mon, Mar 17, 2014 at 1:29 AM, Larry Hastings <larry at hastings.org> wrote:

>
> On behalf of the Python development team, I'm thrilled to announce
> the official release of Python 3.4.
>
>
> Python 3.4 includes a range of improvements of the 3.x series, including
> hundreds of small improvements and bug fixes.  Major new features and
> changes in the 3.4 release series include:
>
> * PEP 428, a "pathlib" module providing object-oriented filesystem paths
> * PEP 435, a standardized "enum" module
> * PEP 436, a build enhancement that will help generate introspection
>            information for builtins
> * PEP 442, improved semantics for object finalization
> * PEP 443, adding single-dispatch generic functions to the standard library
> * PEP 445, a new C API for implementing custom memory allocators
> * PEP 446, changing file descriptors to not be inherited by default
>            in subprocesses
> * PEP 450, a new "statistics" module
> * PEP 451, standardizing module metadata for Python's module import system
> * PEP 453, a bundled installer for the *pip* package manager
> * PEP 454, a new "tracemalloc" module for tracing Python memory allocations
> * PEP 456, a new hash algorithm for Python strings and binary data
> * PEP 3154, a new and improved protocol for pickled objects
> * PEP 3156, a new "asyncio" module, a new framework for asynchronous I/O
>
>
> To download Python 3.4.0 visit:
>
>     http://www.python.org/download/releases/3.4.0/
>
>
> This is a production release.  Please report any issues you notice to:
>
>      http://bugs.python.org/
>
>
> Enjoy!
>
>
> --
> Larry Hastings, Release Manager
> larry at hastings.org
> (on behalf of the entire python-dev team and 3.4's contributors)
> _______________________________________________
> Python-Dev mailing list
> Python-Dev at python.org
> https://mail.python.org/mailman/listinfo/python-dev
> Unsubscribe: https://mail.python.org/mailman/options/python-dev/
> rymg19%40gmail.com
>



-- 
Ryan
If anybody ever asks me why I prefer C++ to C, my answer will be simple:
"It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't think that was
nul-terminated."
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From rosuav at gmail.com  Mon Mar 17 13:03:19 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 04:03:19 +1100
Subject: 'complex' function with string argument.
In-Reply-To: <lg779d$5f4$2@speranza.aioe.org>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
Message-ID: <CAPTjJmrVy35uOtr1Zm-Pc=K_Xkhm1jYgy=D3j1bPM2OvUzPDuQ@mail.gmail.com>

On Tue, Mar 18, 2014 at 3:18 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> You actually answered your own question, as you were asking it. If the doc
> says "whatever you do, don't push the purple button," well, leave the purple
> button alone.      :)   (I don't know, push it if you want)

https://www.wizards.com/magic/magazine/article.aspx?x=mtg/daily/mm/69

> If you monitor the PEP process, or have ever taken part in python-ideas, or
> python-dev (either directly, or just lurking) you will notice that python is
> developed through a very interesting active committee process (that is
> really something phenomenal; cool community).

Not really a committee, more of a champion-and-bikeshedders approach -
often with more than one level of champion, as when a PEP has an
author (the first champion) and either the BDFL or his delegate (the
second champion, whose role is usually just to say yay or nay). It's a
curious process, but one that works fairly well.

> How should one spell a complex number? Should we use i or j ? Should the
> imaginary part be set off somehow?  Should literals be parsed differently
> (or consistently) with correctly formed strings?  Who knows, beats me.
>
> consider:
>>>> complex( 3   +  2   j)
> SyntaxError: invalid syntax
>>>> complex( 3   +2j  )
> (3+2j)
>>>>
> I don't know... you tell me.

That's for the sake of parsing clarity. (Incidentally, the call to
complex() is redundant in each case.) Everything in Python consists of
tokens - those tokens, in your examples, are:

"complex", "(", whitespace, "3", whitespace, "+", whitespace, "2",
whitespace, "j", ")", end of line

and

"complex", "(", whitespace, "3", whitespace, "+", "2j", whitespace,
")", end of line

In the first case, the parser then has two symbol-type tokens ("2" and
"j") separated by whitespace, with no operator. That's a problem. Did
you mean "2+j", or "2==j", etc? Since j is perfectly natural as a
name, it's going to be interpreted that way.

In the second case, that translates into a perfectly valid parse tree,
because "2j" is an imaginary literal.

>>> ast.dump(ast.parse("complex( 3   +2j  )"))
"Module(body=[Expr(value=Call(func=Name(id='complex', ctx=Load()),
args=[BinOp(left=Num(n=3), op=Add(), right=Num(n=2j))], keywords=[],
starargs=None, kwargs=None))])"

The sole argument to complex() is an expression which sums the integer
3 and the imaginary 2j, which results in the complex (3+2j), which
complex() looks at and returns unchanged. And that's what you see.

>>>> complex('3+2j')
> (3+2j)
>>>> complex('3 +2j')
> Traceback (most recent call last):
>   File "<pyshell#17>", line 1, in <module>
>     complex('3 +2j')
> ValueError: complex() arg is a malformed string
>>>>
>
> Again, beats me.  I just don't know.

And now what you're looking at is the construction of a complex from a
string. Now, instead of going by the rules of the Python lexer, it
goes by the rules of the complex constructor. You can't use extra
spaces there. You could, of course, write your own function that
parses whatever format you like (including the use of i instead of j),
or you can use ast.literal_eval to parse a string based on Python's
lexing, but with complex(str) you follow the rules of complex(str).

> Philosophically, I tend to think about it this way. A complex number is like
> any other number. I would not form a PI string like this> ' 3 .14 1 5 9265 3
> . . .'   I would rather see it formed like so, '3.1415926535'

Right.

> This  '3 + 2j'  is not a number, its an algebraic sum.
>
> This  '3+2j'  is a complex number.  Ok, maybe not, but its closer to what we
> expect (I'm sorry, but I like  i  instead  of  j  )

Hmm. That's a pretty tricky distinction. In Python source code, those
two are identical, and they're both rendered as a sum. (Lexically. The
CPython optimizer, and presumably other Pythons' optimizers, will
notice at compile time that you're adding two literals, and store the
sum. But as you see from the AST above, it's the sum of two values.)
It's actually not possible, as far as I know, to truly represent a
complex number; all you can do is represent the sum of a real part and
an imaginary part.

> Also, philosophically, C ignores white space;  python does not.

That's not really anything to do with it. The two languages'
approaches to whitespace inside expressions are identical, save that
Python will only allow newlines if the expression is "clearly
unfinished", eg if it has unbalanced open parens. Horizontal
whitespace is fine in both languages. (Of course, C doesn't even
_have_ a complex literal notation, so the distinction is slightly
moot.)

ChrisA


From breamoreboy at yahoo.co.uk  Mon Mar 17 13:03:21 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 17 Mar 2014 17:03:21 +0000
Subject: test
In-Reply-To: <lg78lt$9p9$1@speranza.aioe.org>
References: <lg2geg$48n$1@speranza.aioe.org>
 <mailman.8158.1394934532.18130.python-list@python.org>
 <lg36h6$hb0$1@speranza.aioe.org>
 <mailman.8166.1394964771.18130.python-list@python.org>
 <lg78lt$9p9$1@speranza.aioe.org>
Message-ID: <lg79sd$9s1$1@ger.gmane.org>

On 17/03/2014 16:42, Mark H Harris wrote:
> On 3/16/14 5:07 AM, Chris ?Kwpolska? Warrick wrote:
>> Why not use the mailing list instead?  It?s a much easier way to
>> access this place.
>
> I prefer to 'pull' rather than receive the 'push'.
>
> The newsreader idea is better because threading works better, and
> because the interface is simpler. I don't know, just preference
> I guess.
>
> I am active on several mailing lists also; they only have list
> servers (not news Usenet server). The Usenet news reader concept
> must be fading away, and many isp(s) are not providing the nntp
> post service these days (Charter stopped it in late 2011).
>
> There are still several free post servers out there that do not
> require registration (some are free but do require registration).
>
> What are most active pythoniacs doing with this these days?
>
> (beats me)
>

Thunderbird and gmane, FWIW on Windows 7.  Several hundred Python 
mailing lists and blogs all available from one place, plus presumably 
tens of thousands of other such beasties for just about everything under 
the sun.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From g.rodola at gmail.com  Mon Mar 17 13:11:39 2014
From: g.rodola at gmail.com (Giampaolo Rodola')
Date: Mon, 17 Mar 2014 18:11:39 +0100
Subject: [Python-Dev] [RELEASED] Python 3.4.0
In-Reply-To: <CAO41-mPV0GcV9EEPjv_DDJAOWL3O7Q6QV1ET5EN=wp-64Rwqrg@mail.gmail.com>
References: <53269663.9050408@hastings.org>
 <CAO41-mPV0GcV9EEPjv_DDJAOWL3O7Q6QV1ET5EN=wp-64Rwqrg@mail.gmail.com>
Message-ID: <CAFYqXL-t7VurJgC8qBo0gKj0QeygNNf4NVVk2O1y3uoX7cxFbA@mail.gmail.com>

The what's new looks truly amazing, with pathlib and asyncio being my
favourite additions.
Thanks for all the hard work.


On Mon, Mar 17, 2014 at 5:57 PM, Ryan Gonzalez <rymg19 at gmail.com> wrote:

> YES!!! +1 to the authors of the statistics and pathlib modules.
>
>
> On Mon, Mar 17, 2014 at 1:29 AM, Larry Hastings <larry at hastings.org>wrote:
>
>>
>> On behalf of the Python development team, I'm thrilled to announce
>> the official release of Python 3.4.
>>
>>
>> Python 3.4 includes a range of improvements of the 3.x series, including
>> hundreds of small improvements and bug fixes.  Major new features and
>> changes in the 3.4 release series include:
>>
>> * PEP 428, a "pathlib" module providing object-oriented filesystem paths
>> * PEP 435, a standardized "enum" module
>> * PEP 436, a build enhancement that will help generate introspection
>>            information for builtins
>> * PEP 442, improved semantics for object finalization
>> * PEP 443, adding single-dispatch generic functions to the standard
>> library
>> * PEP 445, a new C API for implementing custom memory allocators
>> * PEP 446, changing file descriptors to not be inherited by default
>>            in subprocesses
>> * PEP 450, a new "statistics" module
>> * PEP 451, standardizing module metadata for Python's module import system
>> * PEP 453, a bundled installer for the *pip* package manager
>> * PEP 454, a new "tracemalloc" module for tracing Python memory
>> allocations
>> * PEP 456, a new hash algorithm for Python strings and binary data
>> * PEP 3154, a new and improved protocol for pickled objects
>> * PEP 3156, a new "asyncio" module, a new framework for asynchronous I/O
>>
>>
>> To download Python 3.4.0 visit:
>>
>>     http://www.python.org/download/releases/3.4.0/
>>
>>
>> This is a production release.  Please report any issues you notice to:
>>
>>      http://bugs.python.org/
>>
>>
>> Enjoy!
>>
>>
>> --
>> Larry Hastings, Release Manager
>> larry at hastings.org
>> (on behalf of the entire python-dev team and 3.4's contributors)
>> _______________________________________________
>> Python-Dev mailing list
>> Python-Dev at python.org
>> https://mail.python.org/mailman/listinfo/python-dev
>> Unsubscribe: https://mail.python.org/mailman/options/python-dev/
>> rymg19%40gmail.com
>>
>
>
>
> --
> Ryan
> If anybody ever asks me why I prefer C++ to C, my answer will be simple:
> "It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't think that was
> nul-terminated."
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>
>


-- 
Giampaolo - http://grodola.blogspot.com
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From felixonmars at gmail.com  Mon Mar 17 13:18:01 2014
From: felixonmars at gmail.com (Felix Yan)
Date: Tue, 18 Mar 2014 01:18:01 +0800
Subject: Thread._stop() behavior changed in Python 3.4
Message-ID: <279038900.uDlbjECTej@felix-arch>

Hi list,

I noticed a behavior change on Thread._stop() with Python 3.4.

I know the method is an undocumented "feature" itself, but some projects are 
using it, and now they fail.

A minimized snippet to reproduce:

#!/usr/bin/python
import threading
def stale():
    import time
    time.sleep(1000)
t = threading.Thread(target=stale)
t.start()
t._stop()

This works correctly with Python 3.3, the program exits immediately after 
t._stop() called, and no exception was raised.

But with Python 3.4, an AssertionError was raised:

Traceback (most recent call last):
  File "test.py", line 8, in <module>
    t._stop()
  File "/usr/lib/python3.4/threading.py", line 990, in _stop
    assert not lock.locked()
AssertionError

And the program still waits on the sleep().

I know trying to forcefully stop a thread is not really a good practice, but I 
still wonder if there's an easy way to get broken programs to work again, just 
in the way they currently are?

Downstream bug reports, for reference:

http://youtrack.jetbrains.com/issue/PY-12317
https://github.com/paramiko/paramiko/issues/286

Regards,
Felix Yan
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From dia.aliounes at gmail.com  Mon Mar 17 13:18:25 2014
From: dia.aliounes at gmail.com (Alioune Dia)
Date: Mon, 17 Mar 2014 18:18:25 +0100
Subject: [Python-Dev] [RELEASED] Python 3.4.0
In-Reply-To: <CAFYqXL-t7VurJgC8qBo0gKj0QeygNNf4NVVk2O1y3uoX7cxFbA@mail.gmail.com>
References: <53269663.9050408@hastings.org>
 <CAO41-mPV0GcV9EEPjv_DDJAOWL3O7Q6QV1ET5EN=wp-64Rwqrg@mail.gmail.com>
 <CAFYqXL-t7VurJgC8qBo0gKj0QeygNNf4NVVk2O1y3uoX7cxFbA@mail.gmail.com>
Message-ID: <CADbZ2qC0U6eWMGh+zBkbsKw8QeFzN756oUEg8DeZ6akvwrASGA@mail.gmail.com>

yeah , asyncio is a great module, congrat for all jobs you are doing
--Ad | Dakar


2014-03-17 18:11 GMT+01:00 Giampaolo Rodola' <g.rodola at gmail.com>:

> The what's new looks truly amazing, with pathlib and asyncio being my
> favourite additions.
> Thanks for all the hard work.
>
>
> On Mon, Mar 17, 2014 at 5:57 PM, Ryan Gonzalez <rymg19 at gmail.com> wrote:
>
>> YES!!! +1 to the authors of the statistics and pathlib modules.
>>
>>
>> On Mon, Mar 17, 2014 at 1:29 AM, Larry Hastings <larry at hastings.org>wrote:
>>
>>>
>>> On behalf of the Python development team, I'm thrilled to announce
>>> the official release of Python 3.4.
>>>
>>>
>>> Python 3.4 includes a range of improvements of the 3.x series, including
>>> hundreds of small improvements and bug fixes.  Major new features and
>>> changes in the 3.4 release series include:
>>>
>>> * PEP 428, a "pathlib" module providing object-oriented filesystem paths
>>> * PEP 435, a standardized "enum" module
>>> * PEP 436, a build enhancement that will help generate introspection
>>>            information for builtins
>>> * PEP 442, improved semantics for object finalization
>>> * PEP 443, adding single-dispatch generic functions to the standard
>>> library
>>> * PEP 445, a new C API for implementing custom memory allocators
>>> * PEP 446, changing file descriptors to not be inherited by default
>>>            in subprocesses
>>> * PEP 450, a new "statistics" module
>>> * PEP 451, standardizing module metadata for Python's module import
>>> system
>>> * PEP 453, a bundled installer for the *pip* package manager
>>> * PEP 454, a new "tracemalloc" module for tracing Python memory
>>> allocations
>>> * PEP 456, a new hash algorithm for Python strings and binary data
>>> * PEP 3154, a new and improved protocol for pickled objects
>>> * PEP 3156, a new "asyncio" module, a new framework for asynchronous I/O
>>>
>>>
>>> To download Python 3.4.0 visit:
>>>
>>>     http://www.python.org/download/releases/3.4.0/
>>>
>>>
>>> This is a production release.  Please report any issues you notice to:
>>>
>>>      http://bugs.python.org/
>>>
>>>
>>> Enjoy!
>>>
>>>
>>> --
>>> Larry Hastings, Release Manager
>>> larry at hastings.org
>>> (on behalf of the entire python-dev team and 3.4's contributors)
>>> _______________________________________________
>>> Python-Dev mailing list
>>> Python-Dev at python.org
>>> https://mail.python.org/mailman/listinfo/python-dev
>>> Unsubscribe: https://mail.python.org/mailman/options/python-dev/
>>> rymg19%40gmail.com
>>>
>>
>>
>>
>> --
>> Ryan
>> If anybody ever asks me why I prefer C++ to C, my answer will be simple:
>> "It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't think that was
>> nul-terminated."
>>
>>
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>>
>>
>
>
> --
> Giampaolo - http://grodola.blogspot.com
>
>
> _______________________________________________
> Python-Dev mailing list
> Python-Dev at python.org
> https://mail.python.org/mailman/listinfo/python-dev
> Unsubscribe:
> https://mail.python.org/mailman/options/python-dev/dia.aliounes%40gmail.com
>
>
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From solipsis at pitrou.net  Mon Mar 17 13:18:05 2014
From: solipsis at pitrou.net (Antoine Pitrou)
Date: Mon, 17 Mar 2014 17:18:05 +0000 (UTC)
Subject: What does =?utf-8?b?Z2MuZ2V0X29iamVjdHMoKQ==?= return?
References: <lfqcr8$249$1@ger.gmane.org>
 <5320BD3F.5030509@mrabarnett.plus.com> <lfqjgu$kug$1@ger.gmane.org>
 <CAPTjJmqdKZ6qDQ+PZAdxVF-hKN=txKh35ga_C451C2z_hpZZAA@mail.gmail.com>
Message-ID: <loom.20140317T181504-977@post.gmane.org>

Chris Angelico <rosuav <at> gmail.com> writes:
> 
> It's not strictly an implementation detail, beyond that there are
> certain optimizations. For instance...
> 
> >   For CPython 3.4 I guess strings and other atomic types such as ints are
> > not, as well as raw object() instances. Custom class instances on the other
> > hand seem to be under GC control.
> 
> ... strings and ints should never be listed, and custom objects should
> always be listed, but I'd say the non-tracking of object() would be an
> implementation-specific optimization.

These are all implementation details, tied to the fact that the primary
object reclaim mechanism in CPython is reference counting. Other 
implementations may use a full GC and gc.get_objects() may then also
return strings and other "atomic" objects (but the implementation may
also elicit to hack get_objects() in order to closely mimick CPython).

All in all, though, gc.get_objects() is an expensive function call (it
will walk the entire graph of objects tracked by the GC, which can be very
large in non-trivial applications), so it's really only useful for
debugging (and, I'd add, for low-level debugging). In most situations,
gc.get_objects() is certainly the wrong tool to use.

Regards

Antoine.




From solipsis at pitrou.net  Mon Mar 17 13:33:09 2014
From: solipsis at pitrou.net (Antoine Pitrou)
Date: Mon, 17 Mar 2014 17:33:09 +0000 (UTC)
Subject: =?utf-8?b?VGhyZWFkLl9zdG9wKCk=?= behavior changed in Python 3.4
References: <279038900.uDlbjECTej@felix-arch>
Message-ID: <loom.20140317T182601-605@post.gmane.org>


Hi,

Felix Yan <felixonmars <at> gmail.com> writes:
> 
> A minimized snippet to reproduce:
> 
> #!/usr/bin/python
> import threading
> def stale():
>     import time
>     time.sleep(1000)
> t = threading.Thread(target=stale)
> t.start()
> t._stop()
> 
> This works correctly with Python 3.3, the program exits immediately after 
> t._stop() called, and no exception was raised.

Basically what you are doing is abusing a private method because you want
to make the thread daemonic after it was started (a daemonic thread is
not waited for at interpreter exit). Please do note one thing: the _stop()
method does *not* actually stop the thread; it just marks it stopped, but
the underlying OS thread continues to run (and may indeed continue to
execute Python code until the interpreter exits).

So the obvious "solution" here is to mark the thread daemonic before 
starting it.

A possible related improvement would be to relax the contraints on 
Thread.daemon to allow setting the flag on a running thread?

That said, daemon threads (or abuse of the _stop() method as you did) can
lead to instabilities and oddities as some code will continue executing while 
the interpreter starts shutting down. This has been improved but perhaps
not totally solved in recent interpreter versions. A fully correct solution
would involve gracefully telling the thread to shut down, via a boolean
flag, an Event, a file descriptor or any other means.

(if you are interested in this, please open a new issue at 
http://bugs.python.org)

Regards

Antoine.




From rosuav at gmail.com  Mon Mar 17 13:40:51 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 04:40:51 +1100
Subject: Thread._stop() behavior changed in Python 3.4
In-Reply-To: <279038900.uDlbjECTej@felix-arch>
References: <279038900.uDlbjECTej@felix-arch>
Message-ID: <CAPTjJmrNizyUvY=XC+FwKcTv+TDMKQv9YL6dyc3WjiGDtB+6iw@mail.gmail.com>

On Tue, Mar 18, 2014 at 4:18 AM, Felix Yan <felixonmars at gmail.com> wrote:
> I noticed a behavior change on Thread._stop() with Python 3.4.
>
> I know the method is an undocumented "feature" itself, but some projects are
> using it, and now they fail.
>
> I know trying to forcefully stop a thread is not really a good practice, but I
> still wonder if there's an easy way to get broken programs to work again, just
> in the way they currently are?

You're using something that has a leading underscore on the name.
Frankly, you shouldn't be doing that. Your code was already broken,
before 3.4 came along, and it's just that 3.4 highlighted that
brokenness. The PyCharm report that this is a Python 3.4 bug is simply
incorrect. This code should be a strong indication that something's
reaching into places it shouldn't be:

https://github.com/JetBrains/intellij-community/blob/master/python/helpers/pydev/pydevd_comm.py#L109

The solution is to have the thread acknowledge, in some way, that it
needs to shut down. Forcefully stopping a thread is actually a really
bad practice, at least in Python (with OS/2 and VX-REXX, it's a
different matter). Antoine says that this doesn't even stop the thread
(I can't say; I've never used _stop(), for obvious reasons), so this
code was doubly broken. The change in 3.4 should be an excuse to fix
the code so it actually works, and works according to the spec, which
will mean it works on all versions.

ChrisA


From jurko.gospodnetic at pke.hr  Mon Mar 17 13:53:24 2014
From: jurko.gospodnetic at pke.hr (=?UTF-8?B?SnVya28gR29zcG9kbmV0acSH?=)
Date: Mon, 17 Mar 2014 18:53:24 +0100
Subject: What does gc.get_objects() return?
In-Reply-To: <loom.20140317T181504-977@post.gmane.org>
References: <lfqcr8$249$1@ger.gmane.org>
 <5320BD3F.5030509@mrabarnett.plus.com> <lfqjgu$kug$1@ger.gmane.org>
 <CAPTjJmqdKZ6qDQ+PZAdxVF-hKN=txKh35ga_C451C2z_hpZZAA@mail.gmail.com>
 <loom.20140317T181504-977@post.gmane.org>
Message-ID: <lg7cq5$fuv$1@ger.gmane.org>

   Hi.

On 17.3.2014. 18:18, Antoine Pitrou wrote:
> All in all, though, gc.get_objects() is an expensive function call (it
> will walk the entire graph of objects tracked by the GC, which can be very
> large in non-trivial applications), so it's really only useful for
> debugging (and, I'd add, for low-level debugging). In most situations,
> gc.get_objects() is certainly the wrong tool to use.

   I agree, and for the record, we were using it for debugging when I 
started this thread - trying to track down a memory leak. :-)

   gc.get_objects() turned out to be of great help with in resolving the 
issue - in the end we tracked it down to a typical reference counting 
problem in a Python extension DLL. *doh*

   Best regards,
     Jurko Gospodneti?



From mdickinson at enthought.com  Mon Mar 17 13:55:36 2014
From: mdickinson at enthought.com (Mark Dickinson)
Date: Mon, 17 Mar 2014 17:55:36 +0000 (UTC)
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
Message-ID: <loom.20140317T184835-830@post.gmane.org>

Jayanth Koushik <jnkoushik <at> gmail.com> writes:

> "Note: When converting from a string, the string must not contain whitespace
> around the central + or - operator. For example, complex('1+2j') is fine, but
> complex('1 + 2j') raises ValueError."
> 
> Why is this so?

See http://bugs.python.org/issue9574 for a bit more context.  To begin with,
it's not at all clear what *should* be allowed.  If "1 + 2j" is valid, what
about "+ 2j"?  How about "+ 2"?  What about things like "+1.0 + -2.3j"?
Ultimately, I closed that issue because the proposed change seemed like
unnecessary code churn, and there wasn't a clear consensus that the change was
desirable (or even what that change should be).  If it ain't broke, etc.

-- 
Mark




From felixonmars at gmail.com  Mon Mar 17 13:59:52 2014
From: felixonmars at gmail.com (Felix Yan)
Date: Tue, 18 Mar 2014 01:59:52 +0800
Subject: Thread._stop() behavior changed in Python 3.4
In-Reply-To: <loom.20140317T182601-605@post.gmane.org>
References: <279038900.uDlbjECTej@felix-arch>
 <loom.20140317T182601-605@post.gmane.org>
Message-ID: <6089125.ey7IQ53jgg@felix-arch>

On Monday, March 17, 2014 17:33:09 Antoine Pitrou wrote:
> Hi,
> 
> Felix Yan <felixonmars <at> gmail.com> writes:
> > A minimized snippet to reproduce:
> > 
> > #!/usr/bin/python
> > import threading
> > 
> > def stale():
> >     import time
> >     time.sleep(1000)
> > 
> > t = threading.Thread(target=stale)
> > t.start()
> > t._stop()
> > 
> > This works correctly with Python 3.3, the program exits immediately after
> > t._stop() called, and no exception was raised.
> 
> Basically what you are doing is abusing a private method because you want
> to make the thread daemonic after it was started (a daemonic thread is
> not waited for at interpreter exit). Please do note one thing: the _stop()
> method does *not* actually stop the thread; it just marks it stopped, but
> the underlying OS thread continues to run (and may indeed continue to
> execute Python code until the interpreter exits).
> 
> So the obvious "solution" here is to mark the thread daemonic before
> starting it.
> 
> A possible related improvement would be to relax the contraints on
> Thread.daemon to allow setting the flag on a running thread?
> 
> That said, daemon threads (or abuse of the _stop() method as you did) can
> lead to instabilities and oddities as some code will continue executing
> while the interpreter starts shutting down. This has been improved but
> perhaps not totally solved in recent interpreter versions. A fully correct
> solution would involve gracefully telling the thread to shut down, via a
> boolean flag, an Event, a file descriptor or any other means.
> 
> (if you are interested in this, please open a new issue at
> http://bugs.python.org)
> 
> Regards
> 
> Antoine.

Thanks for the detailed explanation!

Actually I didn't used _stop() myself either, but noticed the problem when 
trying to build paramiko against python 3.4.

Thanks especially for the tip that the threads may be still running - actually 
I didn't even think about this part!

For now I just skipped the test suites for paramiko to get the packaging done 
(since the test suites themselves are passed without a problem, just the test 
script made something wrong). I'll try to follow up the issue for paramiko :)

Regards,
Felix Yan
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From ian.g.kelly at gmail.com  Mon Mar 17 14:03:51 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 17 Mar 2014 12:03:51 -0600
Subject: Thread._stop() behavior changed in Python 3.4
In-Reply-To: <CAPTjJmrNizyUvY=XC+FwKcTv+TDMKQv9YL6dyc3WjiGDtB+6iw@mail.gmail.com>
References: <279038900.uDlbjECTej@felix-arch>
 <CAPTjJmrNizyUvY=XC+FwKcTv+TDMKQv9YL6dyc3WjiGDtB+6iw@mail.gmail.com>
Message-ID: <CALwzidkdqEGebjtnAsxGzC0Y1z+k_WZxfSHkBbS9sD6RZy10uQ@mail.gmail.com>

On Mon, Mar 17, 2014 at 11:40 AM, Chris Angelico <rosuav at gmail.com> wrote:
> Antoine says that this doesn't even stop the thread
> (I can't say; I've never used _stop(), for obvious reasons), so this
> code was doubly broken.

I was curious about that -- after all, Python's threads aren't truly
concurrent, so perhaps they could just test the flag each time they
resume -- so I tested it using 3.3.  First I tried simply adding a
print call on to the end of the OP's function:

>>> def stale():
...     import time
...     time.sleep(1000)
...     print('hello')
...
>>> t = threading.Thread(target=stale)
>>> t.start(); t._stop()

No output was printed, so at least a sleeping thread can apparently be
stopped.  Then I tried removing the sleep call:

>>> def stale():
...     for i in range(10): print('hello')
...
>>> t = threading.Thread(target=stale)
>>> t.start(); print('Starting'); t._stop(); print('Stopping')
hello
Starting
Stopping
>>> hello
hello
hello
hello
hello
hello
hello
hello
hello

So yes, despite the lack of true concurrency, a thread can continue to
run after its _stop has been called.


From rosuav at gmail.com  Mon Mar 17 14:08:20 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 05:08:20 +1100
Subject: Thread._stop() behavior changed in Python 3.4
In-Reply-To: <6089125.ey7IQ53jgg@felix-arch>
References: <279038900.uDlbjECTej@felix-arch>
 <loom.20140317T182601-605@post.gmane.org>
 <6089125.ey7IQ53jgg@felix-arch>
Message-ID: <CAPTjJmpgp5NaiVvBmEr6H5hFMjia+gEo=GOATYNZsU8rjwuS7A@mail.gmail.com>

On Tue, Mar 18, 2014 at 4:59 AM, Felix Yan <felixonmars at gmail.com> wrote:
> For now I just skipped the test suites for paramiko to get the packaging done
> (since the test suites themselves are passed without a problem, just the test
> script made something wrong). I'll try to follow up the issue for paramiko :)

I've posted comments on both the issues you linked to. My guess based
on a cursory look at paramiko is that it's a test suite watchdog,
which would be much better implemented with a subprocess; I may be
wrong, though. In any case, if it's just a tests problem, you should
theoretically be able to ignore it.

ChrisA


From felixonmars at gmail.com  Mon Mar 17 14:13:53 2014
From: felixonmars at gmail.com (Felix Yan)
Date: Tue, 18 Mar 2014 02:13:53 +0800
Subject: Thread._stop() behavior changed in Python 3.4
In-Reply-To: <CAPTjJmpgp5NaiVvBmEr6H5hFMjia+gEo=GOATYNZsU8rjwuS7A@mail.gmail.com>
References: <279038900.uDlbjECTej@felix-arch> <6089125.ey7IQ53jgg@felix-arch>
 <CAPTjJmpgp5NaiVvBmEr6H5hFMjia+gEo=GOATYNZsU8rjwuS7A@mail.gmail.com>
Message-ID: <1469242.qze850NkBZ@felix-arch>

On Tuesday, March 18, 2014 05:08:20 Chris Angelico wrote:
> I've posted comments on both the issues you linked to. My guess based
> on a cursory look at paramiko is that it's a test suite watchdog,
> which would be much better implemented with a subprocess; I may be
> wrong, though. In any case, if it's just a tests problem, you should
> theoretically be able to ignore it.
> 
> ChrisA

I was just trying to comment and see yours... Thanks a lot! :D

Regards,
Felix Yan
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From rosuav at gmail.com  Mon Mar 17 14:18:54 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 05:18:54 +1100
Subject: Thread._stop() behavior changed in Python 3.4
In-Reply-To: <1469242.qze850NkBZ@felix-arch>
References: <279038900.uDlbjECTej@felix-arch> <6089125.ey7IQ53jgg@felix-arch>
 <CAPTjJmpgp5NaiVvBmEr6H5hFMjia+gEo=GOATYNZsU8rjwuS7A@mail.gmail.com>
 <1469242.qze850NkBZ@felix-arch>
Message-ID: <CAPTjJmppOBpUfRbniPCaoSj-_k16jwqbz8Z1kPP5OzR212Nj3Q@mail.gmail.com>

On Tue, Mar 18, 2014 at 5:13 AM, Felix Yan <felixonmars at gmail.com> wrote:
> On Tuesday, March 18, 2014 05:08:20 Chris Angelico wrote:
>> I've posted comments on both the issues you linked to. My guess based
>> on a cursory look at paramiko is that it's a test suite watchdog,
>> which would be much better implemented with a subprocess; I may be
>> wrong, though. In any case, if it's just a tests problem, you should
>> theoretically be able to ignore it.
>>
>> ChrisA
>
> I was just trying to comment and see yours... Thanks a lot! :D

Your comment will mean more, since you actually use the thing :)

ChrisA


From marko at pacujo.net  Mon Mar 17 14:15:55 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 17 Mar 2014 20:15:55 +0200
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <mailman.8201.1395075805.18130.python-list@python.org>
Message-ID: <87y508r8ro.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Tue, Mar 18, 2014 at 3:18 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>> Philosophically, I tend to think about it this way. A complex number
>> is like any other number. I would not form a PI string like this> ' 3
>> .14 1 5 9265 3 . . .' I would rather see it formed like so,
>> '3.1415926535'
>
> Right.

Well, Java 7 allows you to embed underscores freely in numeric literals.
Would be a nice addition to Python as well:

   if unit == 'G':
       count *= 1_000_000_000

vs:

   if unit == 'G':
       count *= 1000000000


>> This  '3 + 2j'  is not a number, its an algebraic sum.
>>
>> This '3+2j' is a complex number. Ok, maybe not, but its closer to what
>> we expect (I'm sorry, but I like i instead of j )
>
>Hmm. That's a pretty tricky distinction.

Is "-2.0" a literal?

What's the outcome of

   -2.0.__str__()


Marko


From harrismh777 at gmail.com  Mon Mar 17 14:20:51 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 17 Mar 2014 13:20:51 -0500
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <mailman.8201.1395075805.18130.python-list@python.org>
Message-ID: <lg7ee0$qe1$1@speranza.aioe.org>

On 3/17/14 12:03 PM, Chris Angelico wrote:
>>>> ast.dump(ast.parse("complex( 3   +2j  )"))
> "Module(body=[Expr(value=Call(func=Name(id='complex', ctx=Load()),
> args=[BinOp(left=Num(n=3), op=Add(), right=Num(n=2j))], keywords=[],
> starargs=None, kwargs=None))])"
>
> The sole argument to complex() is an expression which sums the integer
> 3 and the imaginary 2j, which results in the complex (3+2j), which
> complex() looks at and returns unchanged. And that's what you see.

~very nice.

Ok, going along with Mark's comment about this bug report:

> See http://bugs.python.org/issue9574

This string  '3  +2j'  should probably be ok from the complex() string
constructor standpoint, right?

I mean, there might be more than one constructor for string, mighten-it?

marcus


From ian.g.kelly at gmail.com  Mon Mar 17 14:28:05 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 17 Mar 2014 12:28:05 -0600
Subject: 'complex' function with string argument.
In-Reply-To: <87y508r8ro.fsf@elektro.pacujo.net>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <mailman.8201.1395075805.18130.python-list@python.org>
 <87y508r8ro.fsf@elektro.pacujo.net>
Message-ID: <CALwzidkwv3GZ=Kr6YeJyU0ZPudLA3LpFP3Y2sBea+aRD6nMmeQ@mail.gmail.com>

On Mon, Mar 17, 2014 at 12:15 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Is "-2.0" a literal?
>
> What's the outcome of
>
>    -2.0.__str__()

No.  The compiler will try to optimize it into a single constant if it
can, but it has to be done in accordance with the order of operations.
 In that example, the __str__ method is called before the unary - is
applied, resulting in an error.


From jurko.gospodnetic at pke.hr  Mon Mar 17 14:51:13 2014
From: jurko.gospodnetic at pke.hr (=?UTF-8?B?SnVya28gR29zcG9kbmV0acSH?=)
Date: Mon, 17 Mar 2014 19:51:13 +0100
Subject: Thread._stop() behavior changed in Python 3.4
In-Reply-To: <CALwzidkdqEGebjtnAsxGzC0Y1z+k_WZxfSHkBbS9sD6RZy10uQ@mail.gmail.com>
References: <279038900.uDlbjECTej@felix-arch>
 <CAPTjJmrNizyUvY=XC+FwKcTv+TDMKQv9YL6dyc3WjiGDtB+6iw@mail.gmail.com>
 <CALwzidkdqEGebjtnAsxGzC0Y1z+k_WZxfSHkBbS9sD6RZy10uQ@mail.gmail.com>
Message-ID: <lg7g6i$qgg$1@ger.gmane.org>

   Hi.

On 17.3.2014. 19:03, Ian Kelly wrote:
> So yes, despite the lack of true concurrency, a thread can continue to
> run after its _stop has been called.

   Actually 'true' or 'false' concurrency does not matter here.

   CPython supports multiple threads and implements them using 
underlying native OS threads. The fact that it has an internal mutex 
(GIL) preventing it from executing/interpreting Python code at the same 
time in multiple threads (most of the time) does not come into play.. 
When one thread exits its GIL protected section (e.g. finishes 
processing one bytecode instruction and is about to go on to processing 
the next one), another thread may pick up the GIL and do some of its 
work, e.g. print out some output.

   Best regards,
     Jurko Gospodneti?




From rosuav at gmail.com  Mon Mar 17 14:59:50 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 05:59:50 +1100
Subject: 'complex' function with string argument.
In-Reply-To: <87y508r8ro.fsf@elektro.pacujo.net>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <mailman.8201.1395075805.18130.python-list@python.org>
 <87y508r8ro.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmouU=qLMpTj0QL+xjsA8vgCmhiwmQm=V7z_1+yCMCapHQ@mail.gmail.com>

On Tue, Mar 18, 2014 at 5:15 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> This  '3 + 2j'  is not a number, its an algebraic sum.
>>>
>>> This '3+2j' is a complex number. Ok, maybe not, but its closer to what
>>> we expect (I'm sorry, but I like i instead of j )
>>
>>Hmm. That's a pretty tricky distinction.
>
> Is "-2.0" a literal?
>
> What's the outcome of
>
>    -2.0.__str__()

If you mean (-2.0).__str__(), then it returns '-2.0', but that proves
nothing. Lots of objects have a str() which isn't a literal. Closer to
what you're talking about would be repr(), but even then, it doesn't
prove that something's a literal. The easiest way to tell is probably
ast.parse():

>>> ast.dump(ast.parse("-2.0"))
'Module(body=[Expr(value=UnaryOp(op=USub(), operand=Num(n=2.0)))])'

It's an expression consisting of unary minus and the float literal 2.0.

ChrisA


From harrismh777 at gmail.com  Mon Mar 17 15:01:02 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 17 Mar 2014 14:01:02 -0500
Subject: test
References: <lg2geg$48n$1@speranza.aioe.org>
 <mailman.8158.1394934532.18130.python-list@python.org>
 <lg36h6$hb0$1@speranza.aioe.org>
 <mailman.8166.1394964771.18130.python-list@python.org>
 <lg78lt$9p9$1@speranza.aioe.org>
 <mailman.8202.1395075820.18130.python-list@python.org>
Message-ID: <lg7gpb$115$1@speranza.aioe.org>

On 3/17/14 12:03 PM, Mark Lawrence wrote:

> Thunderbird and gmane, FWIW on Windows 7.

I moved my news reader stuff like comp.lang.python over to my
Thunderbird mail client yesterday; works well and is as functional
as sea-monkey ever was. The client is nice and has none of the
short-comings of gg.

The server &Thunderbird complain about the line lengths when in
excess of 79 characters (says it can't post) but posts anyway. I've seen
that at least one|twice.

Gmane looks interesting... gonna try it.

marcus


From marko at pacujo.net  Mon Mar 17 15:22:18 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 17 Mar 2014 21:22:18 +0200
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <mailman.8201.1395075805.18130.python-list@python.org>
 <87y508r8ro.fsf@elektro.pacujo.net>
 <mailman.8218.1395082794.18130.python-list@python.org>
Message-ID: <87siqgr5p1.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Tue, Mar 18, 2014 at 5:15 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> Is "-2.0" a literal?
>>
>> What's the outcome of
>>
>>    -2.0.__str__()
>
> If you mean (-2.0).__str__(), then it returns '-2.0', but that proves
> nothing.

The point is, you don't need to "philosophize" about complex literals
when even negative numbers don't have literals in Python.


Marko


From rosuav at gmail.com  Mon Mar 17 15:32:18 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 06:32:18 +1100
Subject: 'complex' function with string argument.
In-Reply-To: <87siqgr5p1.fsf@elektro.pacujo.net>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <mailman.8201.1395075805.18130.python-list@python.org>
 <87y508r8ro.fsf@elektro.pacujo.net>
 <mailman.8218.1395082794.18130.python-list@python.org>
 <87siqgr5p1.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpjH3P5tcSS5pu8m+Zt2OMO0rpWoxBRSZzaim21A3u9+w@mail.gmail.com>

On Tue, Mar 18, 2014 at 6:22 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> On Tue, Mar 18, 2014 at 5:15 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> Is "-2.0" a literal?
>>>
>>> What's the outcome of
>>>
>>>    -2.0.__str__()
>>
>> If you mean (-2.0).__str__(), then it returns '-2.0', but that proves
>> nothing.
>
> The point is, you don't need to "philosophize" about complex literals
> when even negative numbers don't have literals in Python.

Ah! I get you.

The difference between literals and constants is one that almost never
matters, though. Python may not have a syntax for negative or complex
literals, but it does have notations for various sorts of constants,
which function the same way. (Literals are by definition constants.)
So Python may not have a convenient notation for "number of seconds in
a week" (unless you work with DNS and find the bare integer 604800
convenient), but you can write 7*24*60*60 and it's just as good in a
function:

>>> ast.dump(ast.parse("7*24*60*60"))
'Module(body=[Expr(value=BinOp(left=BinOp(left=BinOp(left=Num(n=7),
op=Mult(), right=Num(n=24)), op=Mult(), right=Num(n=60)), op=Mult(),
right=Num(n=60)))])'
>>> def f(x):
    return x + 7*24*60*60

>>> dis.dis(f)
  2           0 LOAD_FAST                0 (x)
              3 LOAD_CONST               6 (604800)
              6 BINARY_ADD
              7 RETURN_VALUE

There's absolutely no run-time cost to writing it out, and you get to
be flexible with whitespace and such, which you can't do with
literals.

ChrisA


From laguna-mc at mail.com  Mon Mar 17 15:56:38 2014
From: laguna-mc at mail.com (laguna-mc at mail.com)
Date: Mon, 17 Mar 2014 15:56:38 -0400
Subject: Installing binwalk on Portable Python
Message-ID: <20140317195638.22300@gmx.com>

Portable Python 2.7 for Win32 and installed on USB flash drive. I want install Binwalk tool, it have a few depencencies, I installed it first (numpy, matplotlib, libmagic, python-magic)
Then I tried to install binwalk from locally stored source archive file, I tried two ways:

pip install E:\Portable Python 2.7.5.1\binwalk-1.3.0.tar

pip install E:\Portable Python 2.7.5.1\binwalk-1.3.0\src\setup.py

I both cases I got error, below is log:

E:\Portable Python 2.7.5.1\App\Scripts\pip run on 03/17/14 21:25:47
Exception:
Traceback (most recent call last):
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\basecommand.py", line 122, in main
 status = self.run(options, args)
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\commands\install.py", line 257, in run
 InstallRequirement.from_line(name, None))
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line 172, in from_line
 return cls(req, comes_from, url=url, prereleases=prereleases)
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line 70, in __init__
 req = pkg_resources.Requirement.parse(req)
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2606, in parse
 reqs = list(parse_requirements(s))
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2544, in parse_requirements
 line, p, specs = scan_list(VERSION,LINE_END,line,p,(1,2),"version spec")
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2512, in scan_list
 raise ValueError("Expected "+item_name+" in",line,"at",line[p:])
ValueError: ('Expected version spec in', 'E:\\Portable', 'at', ':\\Portable')
-------------------------------------------
What is wrong with this?
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From ian.g.kelly at gmail.com  Mon Mar 17 16:05:58 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 17 Mar 2014 14:05:58 -0600
Subject: Thread._stop() behavior changed in Python 3.4
In-Reply-To: <lg7g6i$qgg$1@ger.gmane.org>
References: <279038900.uDlbjECTej@felix-arch>
 <CAPTjJmrNizyUvY=XC+FwKcTv+TDMKQv9YL6dyc3WjiGDtB+6iw@mail.gmail.com>
 <CALwzidkdqEGebjtnAsxGzC0Y1z+k_WZxfSHkBbS9sD6RZy10uQ@mail.gmail.com>
 <lg7g6i$qgg$1@ger.gmane.org>
Message-ID: <CALwzid=bfiGgV5YCNjeR6Z9C8E0fY7mSb=m4bXtyKs=uz5WpEg@mail.gmail.com>

On Mar 17, 2014 12:53 PM, "Jurko Gospodneti?" <jurko.gospodnetic at pke.hr>
wrote:
>
>   Hi.
>
>
> On 17.3.2014. 19:03, Ian Kelly wrote:
>>
>> So yes, despite the lack of true concurrency, a thread can continue to
>> run after its _stop has been called.
>
>
>   Actually 'true' or 'false' concurrency does not matter here.
>
>   CPython supports multiple threads and implements them using underlying
native OS threads. The fact that it has an internal mutex (GIL) preventing
it from executing/interpreting Python code at the same time in multiple
threads (most of the time) does not come into play.. When one thread exits
its GIL protected section (e.g. finishes processing one bytecode
instruction and is about to go on to processing the next one), another
thread may pick up the GIL and do some of its work, e.g. print out some
output.

Yes, and whenever a thread acquires the GIL it *could* check whether its
_stop flag has been set before it starts executing any Python code.
Apparently though it does not, perhaps for performance reasons.
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From pmawhorter at gmail.com  Mon Mar 17 16:13:52 2014
From: pmawhorter at gmail.com (Peter Mawhorter)
Date: Mon, 17 Mar 2014 13:13:52 -0700
Subject: Installing binwalk on Portable Python
In-Reply-To: <20140317195638.22300@gmx.com>
References: <20140317195638.22300@gmx.com>
Message-ID: <CABaZ=CEhjCLPGG3cm8MuanCSGA01dX67dxCpC75t5PHDJvLTvA@mail.gmail.com>

On Mon, Mar 17, 2014 at 12:56 PM,  <laguna-mc at mail.com> wrote:
> Portable Python 2.7 for Win32 and installed on USB flash drive. I want
> install Binwalk tool, it have a few depencencies,  I installed it first
> (numpy, matplotlib, libmagic,  python-magic)
> Then I tried to install binwalk from locally stored source archive file, I
> tried two ways:
>
> pip install E:\Portable Python 2.7.5.1\binwalk-1.3.0.tar
>
> pip install E:\Portable Python 2.7.5.1\binwalk-1.3.0\src\setup.py
>
> I both cases I got error, below is log:
>
> E:\Portable Python 2.7.5.1\App\Scripts\pip run on 03/17/14 21:25:47
> Exception:
> Traceback (most recent call last):
>   File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\basecommand.py", line 122, in main
>     status = self.run(options, args)
>   File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\commands\install.py", line 257, in run
>     InstallRequirement.from_line(name, None))
>   File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line
> 172, in from_line
>     return cls(req, comes_from, url=url, prereleases=prereleases)
>   File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line
> 70, in __init__
>     req = pkg_resources.Requirement.parse(req)
>   File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2606, in
> parse
>     reqs = list(parse_requirements(s))
>   File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2544, in
> parse_requirements
>     line, p, specs = scan_list(VERSION,LINE_END,line,p,(1,2),"version spec")
>   File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2512, in
> scan_list
>     raise ValueError("Expected "+item_name+" in",line,"at",line[p:])
> ValueError: ('Expected version spec in', 'E:\\Portable', 'at',
> ':\\Portable')
> -------------------------------------------
>
>
>
> What is wrong with this?
> --
> https://mail.python.org/mailman/listinfo/python-list
>

>From your error it looks like you just need quotes around the path
because it has a space in it.

-Peter Mawhorter


From laguna-mc at mail.com  Mon Mar 17 16:58:36 2014
From: laguna-mc at mail.com (laguna-mc at mail.com)
Date: Mon, 17 Mar 2014 16:58:36 -0400
Subject: Installing binwalk on Portable Python
Message-ID: <20140317205836.64790@gmx.com>

I tried: pip install "E:\Portable Python 2.7.5.1\binwalk-1.3.0\src\setup.py"

Error:

E:\Portable Python 2.7.5.1\App\Scripts\pip run on 03/17/14 22:53:51
Exception:
Traceback (most recent call last):
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\basecommand.py", line 122, in main
 status = self.run(options, args)
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\commands\install.py", line 257, in run
 InstallRequirement.from_line(name, None))
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line 172, in from_line
 return cls(req, comes_from, url=url, prereleases=prereleases)
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line 70, in __init__
 req = pkg_resources.Requirement.parse(req)
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2606, in parse
 reqs = list(parse_requirements(s))
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2544, in parse_requirements
 line, p, specs = scan_list(VERSION,LINE_END,line,p,(1,2),"version spec")
 File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2512, in scan_list
 raise ValueError("Expected "+item_name+" in",line,"at",line[p:])
ValueError: ('Expected version spec in', 'E:\\Portable Python 2.7.5.1\\binwalk-1.3.0\\src\\setup.py', 'at', ':\\Portable Python 2.7.5.1\\binwalk-1.3.0\\src\\setup.py')


--------------
----- Original Message -----
From: Peter Mawhorter
Sent: 03/17/14 10:13 PM
To: laguna-mc at mail.com
Subject: Re: Installing binwalk on Portable Python

On Mon, Mar 17, 2014 at 12:56 PM, <laguna-mc at mail.com> wrote: > Portable Python 2.7 for Win32 and installed on USB flash drive. I want > install Binwalk tool, it have a few depencencies, I installed it first > (numpy, matplotlib, libmagic, python-magic) > Then I tried to install binwalk from locally stored source archive file, I > tried two ways: > > pip install E:\Portable Python 2.7.5.1\binwalk-1.3.0.tar > > pip install E:\Portable Python 2.7.5.1\binwalk-1.3.0\src\setup.py > > I both cases I got error, below is log: > > E:\Portable Python 2.7.5.1\App\Scripts\pip run on 03/17/14 21:25:47 > Exception: > Traceback (most recent call last): > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\basecommand.py", line 122, in main > status = self.run(options, args) > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\commands\install.py", line 257, in run > InstallRequirement.from_line(name, None)) > File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line > 172, in from_line > return cls(req, comes_from, url=url, prereleases=prereleases) > File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line > 70, in __init__ > req = pkg_resources.Requirement.parse(req) > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2606, in > parse > reqs = list(parse_requirements(s)) > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2544, in > parse_requirements > line, p, specs = scan_list(VERSION,LINE_END,line,p,(1,2),"version spec") > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2512, in > scan_list > raise ValueError("Expected "+item_name+" in",line,"at",line[p:]) > ValueError: ('Expected version spec in', 'E:\\Portable', 'at', > ':\\Portable') > ------------------------------------------- > > > > What is wrong with this? > -- > https://mail.python.org/mailman/listinfo/python-list > From your error it looks like you just need quotes around the path because it has a space in it. -Peter Mawhorter
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From pmawhorter at gmail.com  Mon Mar 17 17:07:03 2014
From: pmawhorter at gmail.com (Peter Mawhorter)
Date: Mon, 17 Mar 2014 14:07:03 -0700
Subject: Installing binwalk on Portable Python
In-Reply-To: <20140317205836.64790@gmx.com>
References: <20140317205836.64790@gmx.com>
Message-ID: <CABaZ=CEhgwSj3-Vkt1NaGR9Usjse3C+m-k2SfUzWaCOqTihx+g@mail.gmail.com>

On Mon, Mar 17, 2014 at 1:58 PM,  <laguna-mc at mail.com> wrote:
> I  tried: pip install "E:\Portable Python
> 2.7.5.1\binwalk-1.3.0\src\setup.py"
>
> Error:
>
> E:\Portable Python 2.7.5.1\App\Scripts\pip run on 03/17/14 22:53:51
>
> Exception:
> Traceback (most recent call last):
>   File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\basecommand.py", line 122, in main
>     status = self.run(options, args)
>   File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\commands\install.py", line 257, in run
>     InstallRequirement.from_line(name, None))
>   File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line
> 172, in from_line
>     return cls(req, comes_from, url=url, prereleases=prereleases)
>   File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line
> 70, in __init__
>     req = pkg_resources.Requirement.parse(req)
>   File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2606, in
> parse
>     reqs = list(parse_requirements(s))
>   File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2544, in
> parse_requirements
>     line, p, specs = scan_list(VERSION,LINE_END,line,p,(1,2),"version spec")
>   File "E:\Portable Python
> 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2512, in
> scan_list
>     raise ValueError("Expected "+item_name+" in",line,"at",line[p:])
> ValueError: ('Expected version spec in', 'E:\\Portable Python
> 2.7.5.1\\binwalk-1.3.0\\src\\setup.py', 'at', ':\\Portable Python
> 2.7.5.1\\binwalk-1.3.0\\src\\setup.py')
>
>
> --------------

I'm no expert, but when I try to run pip install ... it seems to want
a directory that contains a setup.py file rather than the path of the
setup.py file itself. Try:

pip install "E:\Portable Python 2.7.5.1\binwalk-1.3.0\src"

perhaps?

-Peter Mawhorter


From stutzbach at google.com  Mon Mar 17 17:16:52 2014
From: stutzbach at google.com (Daniel Stutzbach)
Date: Mon, 17 Mar 2014 14:16:52 -0700
Subject: Balanced trees
In-Reply-To: <CAN1F8qU=2K6ysbpnu-JoUtfWfTToRsOaRek0dSQzjPx_sYzPKQ@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <CAN1F8qU=2K6ysbpnu-JoUtfWfTToRsOaRek0dSQzjPx_sYzPKQ@mail.gmail.com>
Message-ID: <CAMMy=OsYUzULRTRHwytiTszd44f3anz43=2DtGALHR3nBGe8JQ@mail.gmail.com>

On Fri, Mar 14, 2014 at 6:13 PM, Joshua Landau <joshua at landau.ws> wrote:
>
> Now, I understand there are downsides to blist. Particularly, I've
>
looked through the "benchmarks" and they seem untruthful.


I worked hard to make those benchmarks as fair as possible.  I recognize
that evaluating your own work always runs the risk of introducing hidden
biases, and I welcome input on how they could be improved.

-- 
Daniel Stutzbach
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From laguna-mc at mail.com  Mon Mar 17 17:52:57 2014
From: laguna-mc at mail.com (laguna-mc at mail.com)
Date: Mon, 17 Mar 2014 17:52:57 -0400
Subject: Installing binwalk on Portable Python
Message-ID: <20140317215257.64780@gmx.com>

Yes, that help.
Installation start, but then failed due to "Pre-requisite failure: failed to find libmagic. Check your installation. Please install the python-magic module, or download and install it from source: ftp://ftp.astron.com/pub/file/' "
Although libmagic was installed using pip.

----- Original Message -----
From: Peter Mawhorter
Sent: 03/17/14 11:07 PM
To: laguna-mc
Subject: Re: Installing binwalk on Portable Python

On Mon, Mar 17, 2014 at 1:58 PM, <laguna-mc at mail.com> wrote: > I tried: pip install "E:\Portable Python > 2.7.5.1\binwalk-1.3.0\src\setup.py" > > Error: > > E:\Portable Python 2.7.5.1\App\Scripts\pip run on 03/17/14 22:53:51 > > Exception: > Traceback (most recent call last): > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\basecommand.py", line 122, in main > status = self.run(options, args) > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\commands\install.py", line 257, in run > InstallRequirement.from_line(name, None)) > File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line > 172, in from_line > return cls(req, comes_from, url=url, prereleases=prereleases) > File "E:\Portable Python 2.7.5.1\App\lib\site-packages\pip\req.py", line > 70, in __init__ > req = pkg_resources.Requirement.parse(req) > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2606, in > parse > reqs = list(parse_requirements(s)) > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2544, in > parse_requirements > line, p, specs = scan_list(VERSION,LINE_END,line,p,(1,2),"version spec") > File "E:\Portable Python > 2.7.5.1\App\lib\site-packages\pip\_vendor\pkg_resources.py", line 2512, in > scan_list > raise ValueError("Expected "+item_name+" in",line,"at",line[p:]) > ValueError: ('Expected version spec in', 'E:\\Portable Python > 2.7.5.1\\binwalk-1.3.0\\src\\setup.py', 'at', ':\\Portable Python > 2.7.5.1\\binwalk-1.3.0\\src\\setup.py') > > > -------------- I'm no expert, but when I try to run pip install ... it seems to want a directory that contains a setup.py file rather than the path of the setup.py file itself. Try: pip install "E:\Portable Python 2.7.5.1\binwalk-1.3.0\src" perhaps? -Peter Mawhorter
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From tjreedy at udel.edu  Mon Mar 17 18:06:50 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 17 Mar 2014 18:06:50 -0400
Subject: 'complex' function with string argument.
In-Reply-To: <loom.20140317T184835-830@post.gmane.org>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <loom.20140317T184835-830@post.gmane.org>
Message-ID: <lg7rle$4q0$1@ger.gmane.org>

On 3/17/2014 1:55 PM, Mark Dickinson wrote:
> Jayanth Koushik <jnkoushik <at> gmail.com> writes:
>
>> "Note: When converting from a string, the string must not contain whitespace
>> around the central + or - operator. For example, complex('1+2j') is fine, but
>> complex('1 + 2j') raises ValueError."
>>
>> Why is this so?
>
> See http://bugs.python.org/issue9574 for a bit more context.  To begin with,
> it's not at all clear what *should* be allowed.  If "1 + 2j" is valid, what
> about "+ 2j"?  How about "+ 2"?  What about things like "+1.0 + -2.3j"?
> Ultimately, I closed that issue because the proposed change seemed like
> unnecessary code churn, and there wasn't a clear consensus that the change was
> desirable (or even what that change should be).  If it ain't broke, etc.

I was not nosy on that issue, but  I agree with 'as is', along with no 
space in Franction("1/2"). Mathematicians genearally write both without 
spaces.

-- 
Terry Jan Reedy



From marko at pacujo.net  Mon Mar 17 18:05:47 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 18 Mar 2014 00:05:47 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
Message-ID: <87mwgoqy4k.fsf@elektro.pacujo.net>

Joshua Landau <joshua at landau.ws>:

> The thing we really need is for the blist containers to become stdlib
> (but not to replace the current list implementation).

Very interesting. Downloaded blist but didn't compile it yet. It *could*
be the missing link.

I would *love* to see some comparative performance results between
blist.sorteddict and an AVL tree. A B+ tree could be nicer to the CPU
cache, but then again, the cache line is only a few pointers wide and
there appears to be a lot of shoving stuff left and right -- based on a
10-second "analysis" of the code:

        while (src >= stop)
                *dst-- = *src--;

Personally, I find it a bit odd to place lists at the center of the
proposal and have trees come out as a side effect. I would rather see it
the other way round: sorteddict -> sortedset et al.

> * It reduces demand for trees:

I would hope it would satisfy the demand for trees.

> nobody jumps at blists because they're rarely the obvious solution.

I haven't jumped at them because they were nowhere to be found on <URL:
http://docs.python.org/3/genindex-B.html>.


Marko


From thrinaxodon at bitch.invalid  Mon Mar 17 18:33:39 2014
From: thrinaxodon at bitch.invalid (Thrinaxodon)
Date: Mon, 17 Mar 2014 18:33:39 -0400
Subject: Venus / GuthVenus for iPhone, Nexus, Droid and Android Jelly Bean
References: <32cfed4b-dd74-4360-baab-03f6dba01bdb@googlegroups.com>
 <cf25883a-f4c9-4b41-ba2b-dc8d4db942e1@googlegroups.com>
 <71ab5220-6d5d-46bf-b33a-16aae6c87109@googlegroups.com>
Message-ID: <MPG.2d91424e2332741598968f@news.eternal-september.org>

In article <71ab5220-6d5d-46bf-b33a-16aae6c87109 at googlegroups.com>, 
bradguth at gmail.com says...
> 
> On Wednesday, February 5, 2014 2:59:23 PM UTC-8, Brad Guth wrote:
> > On Saturday, January 11, 2014 3:52:10 PM UTC-8, Brad Guth wrote:
> > 
> > > NOVA and Discovery Channel each missed this one as of 13+ years ago; 
> > 
> > > 
> > 
> > > GuthVenus 1:1, plus 10x resample/enlargement of the area in question
> > 
> > > 
> > 
> > >  http://bradguth.blogspot.com/2009/07/brad-guth-index.html
> > 
> > > 
> > 
> > >  http://nssdc.gsfc.nasa.gov/imgcat/hires/mgn_c115s095_1.gif
> > 
> > > 
> > 
> > > 
> > 
> > > 
> > 
> > > Our NASA and all of their contracted universities plus numerous others associated somehow missed this one, even after they'd been explicitly informed. Go figure.
> > 
> > > 
> > 
> > > 
> > 
> > > 
> > 
> > >  Be my guest and apply your very own photographic enlargement software, as to viewing this one small but rather interesting topography area of Venus, using your independent deductive expertise as to further enlarge or magnify and simply interpret this extensively mountainous and canyon populated terrain area of Venus that I've focused upon (roughly one third up from the bottom and roughly center), honestly shouldn't be asking too much.  Most of modern PhotoZoom and 
numerous other photographic software variations tend to accomplish this digital enlargement process automatically on the fly, (including iPhone, Safari, Android, Mozilla FireFox, Google Chrome and most other internet browsing forms of image viewing and zooming), although some extra applied filtering and thereby image enhancing for dynamic range compensations (aka contrast boosting) can further improve upon the end result (no direct pixel modifications should ever be 
necessary, because it's all a derivative from the original Magellan radar imaging that's offering a composite of 36 confirming radar scans per pixel, that can always be 100% verified from scratch).
> > 
> > > 
> > 
> > > 
> > 
> > > 
> > 
> > > Using Ctrl+,+,+ gets most older PCs and even the basic Apple notebooks to quickly zoom in, whereas iPhone, Android and MS-W8 as well as Google Chrome accepts touch-pad or screen touch zooming with even somewhat better results of automatic image resampling, so as to keeping the image context reasonably clear or in focus.  However, a regular photographic editing app or software solution like PhotoShop is still going to provide some of the best results plus offering 
dynamic range compensation for a version of added contrast without actually modifying a damn thing as to the raw context of the original, because everything always remains as a direct image derivative.
> > 
> > > 
> > 
> > >  http://photo-editing-software-review.toptenreviews.com/
> > 
> > > 
> > 
> > > 
> > 

HERE'S THE ANSWER:

=======================
>BREAKING NEWSSSSSSSSS
=======================
>
RICHARD LEAKEY JUST DIED DUE TO HEART FAILURE!
>
THE REASONS DESCRIBED BY THE MEDICAL TEAM IS THAT HIS WORK WAS
DISPROVEN, BY NONE OTHER THAN YOUR OWN BASTARD, THRINAXODON.
>
THIS CAUSED LEAKEY'S HEART TO EXPLODE!
>
THRINAXODON DANCED WITH JOY AS HE WAS GRANTED $600,000,000,000.000!
>
TO WASTE YOUR TIME EVEN FURTHER, CHECK OUT THESE LINKS BELOW.
===========================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/threa
d/6f501c469c7af24f#


https://groups.google.com/group/sci.bio.paleontology/browse_thread/threa
d/3aad75c16afb0b82#


====================================

http://thrinaxodon.wordpress.com/

===================================

THRINAXODON ONLY HAD THIS TO SAY:

"I..I...I...Can't believe it. This completely disproved Darwinian
orthodoxy."

===================================

THE BASTARDS AT THE SMITHSONIAN, AND THE LEAKEY FOUNDATION ARE ERODING
WITH FEAR.

===========================
THESE ASSHOLES ARE GOING TO DIE:
THOMAS AQUINAS;
ALDOUS HUXLEY;
BOB CASANVOVA;
SkyEyes;
DAVID IAIN GRIEG;
MARK ISAAK;
JOHN HARSHAM;
RICHARD NORMAN;
DR. DOOLITTLE;
CHARLES DARWIN;
MARK HORTON;
ERIK SIMPSON;
HYPATIAB7;
PAUL J. GANS;
JILLERY;
WIKI TRIK;
THRINAXODON;
PETER NYIKOS;
RON OKIMOTO;
JOHN S. WILKINS
===========================

THRINAXODON WAS SCOURING ANOTHER DEVONIAN FOSSIL BED, AND FOUND A
HUMAN SKULL, AND A HUMAN FEMUR. HE ANALYSED THE FINDS, AND SAW THAT
THEY WERE NOT NORMAL ROCKS. THESE WERE FOSSILIZED BONES. THEY EVEN HAD
TOOTH MARKS ON THEM. SO, THRINAXODON BROUGHT THEM TO THE LEAKEY
FOUNDATION, THEY UTTERLY DISMISSED IT, AND SAID, "We want to keep
people thinking that humans evolved 2 Ma." THRINAXODON BROUGHT HIS
SWORD, AND SAID, "SCIENCE CORRECTS ITSELF." RICHARD LEAKEY SAID, "That
is a myth, for people to believe in science." THRINAXODON PLANS TO
BRING DOOM TO SCIENCE, ITSELF.

============================

THRINAXODON IS NOW ON REDDIT 


From skip at pobox.com  Mon Mar 17 19:59:44 2014
From: skip at pobox.com (Skip Montanaro)
Date: Mon, 17 Mar 2014 18:59:44 -0500
Subject: 'complex' function with string argument.
In-Reply-To: <lg7rle$4q0$1@ger.gmane.org>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <loom.20140317T184835-830@post.gmane.org>
 <lg7rle$4q0$1@ger.gmane.org>
Message-ID: <CANc-5UzEHLBDcHVdt9odKX24hp7=rdGtBTBiWjO7Me_BEwgGDg@mail.gmail.com>

On Mon, Mar 17, 2014 at 5:06 PM, Terry Reedy <tjreedy at udel.edu> wrote:
> Mathematicians genearally write both without spaces.

Mathematicians also have a tendency to use single letter variables and
often escape into non-ASCII character sets as well. <wink>

Perhaps it's worth pointing out that pylint complains about most/many
infix operations if you don't surround the operator with white space.
And, complex expressions work just fine with white space around the
operator:

>>> 1 + 2j
(1+2j)

Personally, I'm agnostic to the proposed change. I don't use complex
numbers in my work, and I suspect that creating complex numbers from
strings is an extremely small corner case.

Skip


From joshua at landau.ws  Mon Mar 17 20:08:27 2014
From: joshua at landau.ws (Joshua Landau)
Date: Tue, 18 Mar 2014 00:08:27 +0000
Subject: Balanced trees
In-Reply-To: <CAMMy=OsYUzULRTRHwytiTszd44f3anz43=2DtGALHR3nBGe8JQ@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <CAN1F8qU=2K6ysbpnu-JoUtfWfTToRsOaRek0dSQzjPx_sYzPKQ@mail.gmail.com>
 <CAMMy=OsYUzULRTRHwytiTszd44f3anz43=2DtGALHR3nBGe8JQ@mail.gmail.com>
Message-ID: <CAN1F8qUqVnhjxXEUnub36GEwK_DD+ukKK2GwA5wYku0s=wpdgA@mail.gmail.com>

On 17 March 2014 21:16, Daniel Stutzbach <stutzbach at google.com> wrote:
> On Fri, Mar 14, 2014 at 6:13 PM, Joshua Landau <joshua at landau.ws> wrote:
>>
>> Now, I understand there are downsides to blist. Particularly, I've
>> looked through the "benchmarks" and they seem untruthful.
>
> I worked hard to make those benchmarks as fair as possible.  I recognize
> that evaluating your own work always runs the risk of introducing hidden
> biases, and I welcome input on how they could be improved.

Thanks.  First, I want to state that there are two aspects to my
claim. The first is that these benchmarks to not represent typical
use-cases. I will not go too far into this, though, because it's
mostly obvious.

The second is that of the the flaws in the benchmarks themselves.

I'll go through in turn some that are apparent to me:

"Create from an iterator" gives me relatively different results when I
run it (Python 3).

"Delete a slice" is fudged from its inclusion of multiplication, which
is far faster on blists. I admit that it's not obvious how to fix
this.

"First in, first out (FIFO)" should be "x.append(0); x.pop(0)".

"Last in, first out (LIFO)" should use "pop()" over "pop(-1)",
although I admit it shouldn't make a meaningful difference.

"Sort *" are really unfair because they put initialisation in the
timed part and all have keys. The benchmarks on Github are less bad,
but the website really should include all of them and fix the
remaining problems. I do understand that TimSort isn't the most suited
algorithm, though, so I won't read too far into these results.

Further, some of these tests don't show growth where they should, such
as in getitem. The growth is readily apparent when measured as such:

>>> python -m timeit -s "from random import choice; import blist; lst = blist.blist(range(10**0))" "choice(lst)"
1000000 loops, best of 3: 1.18 usec per loop

>>> python -m timeit -s "from random import choice; import blist; lst = blist.blist(range(10**8))" "choice(lst)"
1000000 loops, best of 3: 1.56 usec per loop

Lower size ranges are hidden by the function-call overhead.
Perhaps this effect is to do with caching, in which case the limits of
the cache should be explained more readily.

Nevertheless, my enthusiasm for blist as an alternative stdlib
implementation remains. There are obvious and large advantages to be
had, sometimes when you wouldn't even expect. The slower aspects of
blist are also rarely part of the bottlenecks of programs. So yeah, go
for it.


From rosuav at gmail.com  Mon Mar 17 20:16:48 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 11:16:48 +1100
Subject: 'complex' function with string argument.
In-Reply-To: <CANc-5UzEHLBDcHVdt9odKX24hp7=rdGtBTBiWjO7Me_BEwgGDg@mail.gmail.com>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <loom.20140317T184835-830@post.gmane.org>
 <lg7rle$4q0$1@ger.gmane.org>
 <CANc-5UzEHLBDcHVdt9odKX24hp7=rdGtBTBiWjO7Me_BEwgGDg@mail.gmail.com>
Message-ID: <CAPTjJmpMw7fnU9L8OKMSvyQJZ8t9uM3VbzZxHzwoU0dV6wHaLQ@mail.gmail.com>

On Tue, Mar 18, 2014 at 10:59 AM, Skip Montanaro <skip at pobox.com> wrote:
> Perhaps it's worth pointing out that pylint complains about most/many
> infix operations if you don't surround the operator with white space.

IMO that's excessive. Not every infix operator needs whitespace.

ChrisA


From mok-kong.shen at t-online.de  Mon Mar 17 20:32:05 2014
From: mok-kong.shen at t-online.de (Mok-Kong Shen)
Date: Tue, 18 Mar 2014 01:32:05 +0100
Subject: Ordering in the printout of a dictionary
Message-ID: <lg8462$fnk$1@news.albasani.net>


Could someone kindly explain a phenomenon in the following where:

(1) I first typed in a dictionary but got a printout in a reordered
form.

(2) I then typed in the reordered form but got a printout in the
order that I typed in originally in (1).

That is, there is no stable "standard" ordering. Why is that so?

Is there a way to force a certain ordering of the printout or else
somehow manage to get at least a certain stable ordering of the
printout (i.e. input and output are identical)?

Thanks in advance.

M. K. Shen
------------------------------------------

 >>> {'label': 3, 'parent': 0, 'left child': 1, 'right child': 2}
{'right child': 2, 'parent': 0, 'left child': 1, 'label': 3}
 >>> {'right child': 2, 'parent': 0, 'left child': 1, 'label': 3}
{'label': 3, 'parent': 0, 'left child': 1, 'right child': 2}


From leobutcher5 at gmail.com  Mon Mar 17 20:42:46 2014
From: leobutcher5 at gmail.com (leobutcher5 at gmail.com)
Date: Mon, 17 Mar 2014 17:42:46 -0700 (PDT)
Subject: Python Docs & Download servers not accessable from Egypt
Message-ID: <cfa22dd8-983c-47aa-bac5-27b40131f322@googlegroups.com>

Hello,

I just want to report a python web sites specific problem I don't know if this is the right place to report it

I can't seem to access docs.python.org, mail.python.org, or even legacy.python.org
from my ISP in Egypt "LinkDotNet" the dynamic IP range I noticed while facing this problem is 41.130.xx.xx
please tell me if you need any further info

Thanks


From rosuav at gmail.com  Mon Mar 17 20:48:04 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 11:48:04 +1100
Subject: Ordering in the printout of a dictionary
In-Reply-To: <lg8462$fnk$1@news.albasani.net>
References: <lg8462$fnk$1@news.albasani.net>
Message-ID: <CAPTjJmq8tDjHP2ELS1YN3j+gwopBJUCSQGB+Viq=RyHfcpKxkg@mail.gmail.com>

On Tue, Mar 18, 2014 at 11:32 AM, Mok-Kong Shen
<mok-kong.shen at t-online.de> wrote:
> Could someone kindly explain a phenomenon in the following where:
>
> (1) I first typed in a dictionary but got a printout in a reordered
> form.
>
> (2) I then typed in the reordered form but got a printout in the
> order that I typed in originally in (1).
>
> That is, there is no stable "standard" ordering. Why is that so?

A dictionary is simply a mapping from keys to values. It has no ordering.

> Is there a way to force a certain ordering of the printout or else
> somehow manage to get at least a certain stable ordering of the
> printout (i.e. input and output are identical)?

Yes; instead of simply printing it out (which calls repr()),
explicitly iterate over it, like this:

def display(d):
    return '{'+','.join('%r: %r'%(key,d[key]) for key in sorted(d))+'}'

>>> print(display({'label': 3, 'parent': 0, 'left child': 1, 'right child': 2}))
{'label': 3, 'left child': 1, 'parent': 0, 'right child': 2}

That will be consistent, and will also always be sorted, which will
probably be what you want for human-readable display. At least, it's
consistent as long as the keys all sort consistently, which they will
if you use simple strings. Other types of keys may not work, and in
fact mixing types may cause an exception:

>>> print(display({True:1,"Hello":2}))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in display
TypeError: unorderable types: str() < bool()

But for strings, this is the easiest way to get what you're looking for.

ChrisA


From rosuav at gmail.com  Mon Mar 17 20:49:46 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 11:49:46 +1100
Subject: Python Docs & Download servers not accessable from Egypt
In-Reply-To: <cfa22dd8-983c-47aa-bac5-27b40131f322@googlegroups.com>
References: <cfa22dd8-983c-47aa-bac5-27b40131f322@googlegroups.com>
Message-ID: <CAPTjJmpP9Mg=o4DZKtfdmvkYsBxVfJ6_sfhWtX6mGa40MtMXeQ@mail.gmail.com>

On Tue, Mar 18, 2014 at 11:42 AM,  <leobutcher5 at gmail.com> wrote:
> Hello,
>
> I just want to report a python web sites specific problem I don't know if this is the right place to report it
>
> I can't seem to access docs.python.org, mail.python.org, or even legacy.python.org
> from my ISP in Egypt "LinkDotNet" the dynamic IP range I noticed while facing this problem is 41.130.xx.xx
> please tell me if you need any further info

What IP address is docs.python.org for you? Try using 'dig' or 'ping'
on it. For me, it's:

docs.python.org. 60625 IN CNAME dinsdale.python.org.
dinsdale.python.org. 60625 IN A 82.94.164.162

ChrisA


From stutzbach at google.com  Mon Mar 17 21:01:24 2014
From: stutzbach at google.com (Daniel Stutzbach)
Date: Mon, 17 Mar 2014 18:01:24 -0700
Subject: Balanced trees
In-Reply-To: <CAN1F8qUqVnhjxXEUnub36GEwK_DD+ukKK2GwA5wYku0s=wpdgA@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <CAN1F8qU=2K6ysbpnu-JoUtfWfTToRsOaRek0dSQzjPx_sYzPKQ@mail.gmail.com>
 <CAMMy=OsYUzULRTRHwytiTszd44f3anz43=2DtGALHR3nBGe8JQ@mail.gmail.com>
 <CAN1F8qUqVnhjxXEUnub36GEwK_DD+ukKK2GwA5wYku0s=wpdgA@mail.gmail.com>
Message-ID: <CAMMy=OveYrvz+SZkbk9WvdrmsQMEx3_HVWSkcatbZC4A5jzD8Q@mail.gmail.com>

On Mon, Mar 17, 2014 at 5:08 PM, Joshua Landau <joshua at landau.ws> wrote:

> Thanks.  First, I want to state that there are two aspects to my
>  claim. The first is that these benchmarks to not represent typical
> use-cases. I will not go too far into this, though, because it's
> mostly obvious.
>

I would love to have include macro-benchmarks.  I keep waiting for the PyPy
benchmark suite to get ported to Python 3...


> "Create from an iterator" gives me relatively different results when I
> run it (Python 3).
>

The graphs were originally created to compare vanilla Python with a Python
modified to use blist as the built-in list type.  I think I used Python
3.1, but I'm not certain.  As I recall, the built-in type has a few small
advantages over any third-party extension type, so that might be what
you're seeing.  Alternately, something may have changed between Python
versions.


> "Delete a slice" is fudged from its inclusion of multiplication, which
> is far faster on blists. I admit that it's not obvious how to fix
> this.
>

I could move the initialization into the timed part, similar to what I did
for sort (see below).  That has downsides too, of course, but it might be
an improvement.


> "First in, first out (FIFO)" should be "x.append(0); x.pop(0)".
>

Wow, I mangled that one badly.


> "Last in, first out (LIFO)" should use "pop()" over "pop(-1)",
> although I admit it shouldn't make a meaningful difference.
>

I like pop(-1) because it's explicit rather than implicit.  I agree it
shouldn't make a meaningful difference.


> "Sort *" are really unfair because they put initialisation in the
> timed part


That's a limitation of timeit.  The setup step is only executed once.  If I
put the initialization there, every sort after the first one would be
sorting a pre-sorted list.  If you compare the "Create form an iterator"
and "Sort a random list", you'll see that the initialization cost is
dwarfed by the sorting cost for n > 15 or so.


> and all have keys.


If you use classes with __lt__ methods instead of keys, the cost is
dominated by the calls to __lt__.  You're right that I should include both,
though.


> >>> python -m timeit -s "from random import choice; import blist; lst =
> blist.blist(range(10**0))" "choice(lst)"
> 1000000 loops, best of 3: 1.18 usec per loop
>
> >>> python -m timeit -s "from random import choice; import blist; lst =
> blist.blist(range(10**8))" "choice(lst)"
> 1000000 loops, best of 3: 1.56 usec per loop
>
> Lower size ranges are hidden by the function-call overhead.
> Perhaps this effect is to do with caching, in which case the limits of
> the cache should be explained more readily.
>

That's definitely a cache issue, which is always a risk with
micro-benchmarks.  I see growth even for the built-in list:

gnusto:~$ python -m timeit -s "from random import choice; lst =
list(range(10**0))" "choice(lst)"
1000000 loops, best of 3: 0.349 usec per loop
gnusto:~$ python -m timeit -s "from random import choice; lst =
list(range(10**8))" "choice(lst)"
1000000 loops, best of 3: 0.634 usec per loop

I agree it's more interesting to pick items randomly instead of always
querying the same index.  The overhead of choice() is kind of a problem,
though.  Since I'm only plotting up to 10**5, I'd expect these to look more
or less flat.

Thanks for all of the feedback.  I filed a bug with myself to improve the
metrics:
https://github.com/DanielStutzbach/blist/issues/64

-- 
Daniel Stutzbach
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From skip at pobox.com  Mon Mar 17 21:07:31 2014
From: skip at pobox.com (Skip Montanaro)
Date: Mon, 17 Mar 2014 20:07:31 -0500
Subject: 'complex' function with string argument.
In-Reply-To: <CAPTjJmpMw7fnU9L8OKMSvyQJZ8t9uM3VbzZxHzwoU0dV6wHaLQ@mail.gmail.com>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <loom.20140317T184835-830@post.gmane.org>
 <lg7rle$4q0$1@ger.gmane.org>
 <CANc-5UzEHLBDcHVdt9odKX24hp7=rdGtBTBiWjO7Me_BEwgGDg@mail.gmail.com>
 <CAPTjJmpMw7fnU9L8OKMSvyQJZ8t9uM3VbzZxHzwoU0dV6wHaLQ@mail.gmail.com>
Message-ID: <CANc-5UzutPcFuC8e46NpBT28cA9VYuniApATpHmbc39PvZCPLA@mail.gmail.com>

On Mon, Mar 17, 2014 at 7:16 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Tue, Mar 18, 2014 at 10:59 AM, Skip Montanaro <skip at pobox.com> wrote:
>> Perhaps it's worth pointing out that pylint complains about most/many
>> infix operations if you don't surround the operator with white space.
>
> IMO that's excessive. Not every infix operator needs whitespace.

I wasn't suggesting it was the only way things could be done. Just
pointing out that there is enough common practice out there to suggest
that white space around infix operators is often the preferred way of
doing things. Quoting from PEP 8:

If operators with different priorities are used, consider adding
whitespace around the operators with the lowest priority(ies). Use
your own judgment; however, never use more than one space, and always
have the same amount of whitespace on both sides of a binary operator.

Yes:

i = i + 1
submitted += 1
x = x*2 - 1
hypot2 = x*x + y*y
c = (a+b) * (a-b)

...

My point is that accommodating white space around the + or - sign
isn't altogether unreasonable.

Maybe PEP 8 needs to be tweaked with an example of good complex
literal practice?

Skip


From gordon at panix.com  Mon Mar 17 22:56:21 2014
From: gordon at panix.com (John Gordon)
Date: Tue, 18 Mar 2014 02:56:21 +0000 (UTC)
Subject: Ordering in the printout of a dictionary
References: <lg8462$fnk$1@news.albasani.net>
 <mailman.8231.1395103693.18130.python-list@python.org>
Message-ID: <lg8ckl$aro$1@reader1.panix.com>

In <mailman.8231.1395103693.18130.python-list at python.org> Chris Angelico <rosuav at gmail.com> writes:

> > Is there a way to force a certain ordering of the printout or else
> > somehow manage to get at least a certain stable ordering of the
> > printout (i.e. input and output are identical)?

> Yes; instead of simply printing it out (which calls repr()),
> explicitly iterate over it, like this:

> def display(d):
>     return '{'+','.join('%r: %r'%(key,d[key]) for key in sorted(d))+'}'

You could also use the OrderedDict type, which is subclass of dict that
preserves insertion order.

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon at panix.com    watch 'House', or a real serial killer to watch 'Dexter'.



From bradguth at yahoo.com  Mon Mar 17 23:45:17 2014
From: bradguth at yahoo.com (Brad Guth)
Date: Mon, 17 Mar 2014 20:45:17 -0700
Subject: Venus / GuthVenus for iPhone, Nexus, Droid and Android Jelly Bean
In-Reply-To: <MPG.2d91424e2332741598968f@news.eternal-september.org>
References: <32cfed4b-dd74-4360-baab-03f6dba01bdb@googlegroups.com>
 <cf25883a-f4c9-4b41-ba2b-dc8d4db942e1@googlegroups.com>
 <71ab5220-6d5d-46bf-b33a-16aae6c87109@googlegroups.com>
 <MPG.2d91424e2332741598968f@news.eternal-september.org>
Message-ID: <lg8ff4$lgr$1@dont-email.me>

On 3/17/2014 3:33 PM, Thrinaxodon wrote:
> In article <71ab5220-6d5d-46bf-b33a-16aae6c87109 at googlegroups.com>,
> bradguth at gmail.com says...
>>
>> On Wednesday, February 5, 2014 2:59:23 PM UTC-8, Brad Guth wrote:
>>> On Saturday, January 11, 2014 3:52:10 PM UTC-8, Brad Guth wrote:
>>>
>>>> NOVA and Discovery Channel each missed this one as of 13+ years ago;
>>>
>>>>
>>>
>>>> GuthVenus 1:1, plus 10x resample/enlargement of the area in question
>>>
>>>>
>>>
>>>>   http://bradguth.blogspot.com/2009/07/brad-guth-index.html
>>>
>>>>
>>>
>>>>   http://nssdc.gsfc.nasa.gov/imgcat/hires/mgn_c115s095_1.gif
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> Our NASA and all of their contracted universities plus numerous others associated somehow missed this one, even after they'd been explicitly informed. Go figure.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>   Be my guest and apply your very own photographic enlargement software, as to viewing this one small but rather interesting topography area of Venus, using your independent deductive expertise as to further enlarge or magnify and simply interpret this extensively mountainous and canyon populated terrain area of Venus that I've focused upon (roughly one third up from the bottom and roughly center), honestly shouldn't be asking too much.  Most of modern PhotoZoom and
> numerous other photographic software variations tend to accomplish this digital enlargement process automatically on the fly, (including iPhone, Safari, Android, Mozilla FireFox, Google Chrome and most other internet browsing forms of image viewing and zooming), although some extra applied filtering and thereby image enhancing for dynamic range compensations (aka contrast boosting) can further improve upon the end result (no direct pixel modifications should ever be
> necessary, because it's all a derivative from the original Magellan radar imaging that's offering a composite of 36 confirming radar scans per pixel, that can always be 100% verified from scratch).
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> Using Ctrl+,+,+ gets most older PCs and even the basic Apple notebooks to quickly zoom in, whereas iPhone, Android and MS-W8 as well as Google Chrome accepts touch-pad or screen touch zooming with even somewhat better results of automatic image resampling, so as to keeping the image context reasonably clear or in focus.  However, a regular photographic editing app or software solution like PhotoShop is still going to provide some of the best results plus offering
> dynamic range compensation for a version of added contrast without actually modifying a damn thing as to the raw context of the original, because everything always remains as a direct image derivative.
>>>
>>>>
>>>
>>>>   http://photo-editing-software-review.toptenreviews.com/
>>>
>>>>
>>>
>>>>
>>>
>
> HERE'S THE ANSWER:
>
> =======================
>> BREAKING NEWSSSSSSSSS
> =======================
>>
> RICHARD LEAKEY JUST DIED DUE TO HEART FAILURE!
>>
> THE REASONS DESCRIBED BY THE MEDICAL TEAM IS THAT HIS WORK WAS
> DISPROVEN, BY NONE OTHER THAN YOUR OWN BASTARD, THRINAXODON.
>>
> THIS CAUSED LEAKEY'S HEART TO EXPLODE!
>>
> THRINAXODON DANCED WITH JOY AS HE WAS GRANTED $600,000,000,000.000!
>>
> TO WASTE YOUR TIME EVEN FURTHER, CHECK OUT THESE LINKS BELOW.
> ===========================
> EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:
>
> https://groups.google.com/group/sci.bio.paleontology/browse_thread/threa
> d/6f501c469c7af24f#
>
>
> https://groups.google.com/group/sci.bio.paleontology/browse_thread/threa
> d/3aad75c16afb0b82#
>
>
> ====================================
>
> http://thrinaxodon.wordpress.com/
>
> ===================================
>
> THRINAXODON ONLY HAD THIS TO SAY:
>
> "I..I...I...Can't believe it. This completely disproved Darwinian
> orthodoxy."
>
> ===================================
>
> THE BASTARDS AT THE SMITHSONIAN, AND THE LEAKEY FOUNDATION ARE ERODING
> WITH FEAR.
>
> ===========================
> THESE ASSHOLES ARE GOING TO DIE:
> THOMAS AQUINAS;
> ALDOUS HUXLEY;
> BOB CASANVOVA;
> SkyEyes;
> DAVID IAIN GRIEG;
> MARK ISAAK;
> JOHN HARSHAM;
> RICHARD NORMAN;
> DR. DOOLITTLE;
> CHARLES DARWIN;
> MARK HORTON;
> ERIK SIMPSON;
> HYPATIAB7;
> PAUL J. GANS;
> JILLERY;
> WIKI TRIK;
> THRINAXODON;
> PETER NYIKOS;
> RON OKIMOTO;
> JOHN S. WILKINS
> ===========================
>
> THRINAXODON WAS SCOURING ANOTHER DEVONIAN FOSSIL BED, AND FOUND A
> HUMAN SKULL, AND A HUMAN FEMUR. HE ANALYSED THE FINDS, AND SAW THAT
> THEY WERE NOT NORMAL ROCKS. THESE WERE FOSSILIZED BONES. THEY EVEN HAD
> TOOTH MARKS ON THEM. SO, THRINAXODON BROUGHT THEM TO THE LEAKEY
> FOUNDATION, THEY UTTERLY DISMISSED IT, AND SAID, "We want to keep
> people thinking that humans evolved 2 Ma." THRINAXODON BROUGHT HIS
> SWORD, AND SAID, "SCIENCE CORRECTS ITSELF." RICHARD LEAKEY SAID, "That
> is a myth, for people to believe in science." THRINAXODON PLANS TO
> BRING DOOM TO SCIENCE, ITSELF.
>
> ============================
>
> THRINAXODON IS NOW ON REDDIT
>
Direct death threats should be kept to a minimum.

 > ===========================
 > THESE ASSHOLES ARE GOING TO DIE:
 > THOMAS AQUINAS;
 > ALDOUS HUXLEY;
 > BOB CASANVOVA;
 > SkyEyes;
 > DAVID IAIN GRIEG;
 > MARK ISAAK;
 > JOHN HARSHAM;
 > RICHARD NORMAN;
 > DR. DOOLITTLE;
 > CHARLES DARWIN;
 > MARK HORTON;
 > ERIK SIMPSON;
 > HYPATIAB7;
 > PAUL J. GANS;
 > JILLERY;
 > WIKI TRIK;
 > THRINAXODON;
 > PETER NYIKOS;
 > RON OKIMOTO;
 > JOHN S. WILKINS
 > ===========================

You may want to revise that manifesto to read 'suffer and pay dearly' 
instead of "GOING TO DIE", unless you meant via natural causes.



From steve at pearwood.info  Tue Mar 18 00:08:11 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 18 Mar 2014 04:08:11 GMT
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <mailman.8201.1395075805.18130.python-list@python.org>
 <87y508r8ro.fsf@elektro.pacujo.net>
 <mailman.8218.1395082794.18130.python-list@python.org>
 <87siqgr5p1.fsf@elektro.pacujo.net>
Message-ID: <5327c6ab$0$2923$c3e8da3$76491128@news.astraweb.com>

On Mon, 17 Mar 2014 21:22:18 +0200, Marko Rauhamaa wrote:

> Chris Angelico <rosuav at gmail.com>:
> 
>> On Tue, Mar 18, 2014 at 5:15 AM, Marko Rauhamaa <marko at pacujo.net>
>> wrote:
>>> Is "-2.0" a literal?
>>>
>>> What's the outcome of
>>>
>>>    -2.0.__str__()
>>
>> If you mean (-2.0).__str__(), then it returns '-2.0', but that proves
>> nothing.
> 
> The point is, you don't need to "philosophize" about complex literals
> when even negative numbers don't have literals in Python.

But Python *does* have complex (well, imaginary to be precise) literals. 
The j suffix to a number makes it complex:

py> type(2j)
<class 'complex'>


Complex numbers with both a real and imaginary component are not treated 
as literals:

py> import ast
py> ast.dump(ast.parse("2j"))
'Module(body=[Expr(value=Num(n=2j))])'
py> ast.dump(ast.parse("1+2j"))
'Module(body=[Expr(value=BinOp(left=Num(n=1), op=Add(), 
right=Num(n=2j)))])'


and in recent versions, the peephole optimizer optimizes them:

py> from dis import dis
py> dis("1+2j")
  1           0 LOAD_CONST               2 ((1+2j)) 
              3 RETURN_VALUE         



-- 
Steven


From steve at pearwood.info  Tue Mar 18 00:52:35 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 18 Mar 2014 04:52:35 GMT
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
Message-ID: <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>

On Mon, 17 Mar 2014 11:18:56 -0500, Mark H Harris wrote:

> How should one spell a complex number? Should we use i or j ? Should the
> imaginary part be set off somehow?  Should literals be parsed
> differently (or consistently) with correctly formed strings?  Who knows,
> beats me.

With respect, that's just because you would make a lousy language 
designer :-) The answer to most of those questions should be pretty 
obvious, with perhaps just one that isn't clear.

"How should one spell a complex number?" There is perfectly good syntax 
for complex numbers used by mathematicians and engineers for over a 
century. There is no need to invent something different just for the sake 
of being different:

    Yes:   2+3i or 2+3j
    No:    @2|3?


"Should we use i or j ?" There are good reasons for both i and j. This 
one comes down to personal preference.


"Should the imaginary part be set off somehow?" What do you mean "set 
off"? Why do you want to? Since the imaginary part can appear on its own:

    z = 3j

we cannot make "setting off" compulsory. Once you have syntax for complex 
numbers with an imaginary component, everything else Just Works with no 
additional effort:

    z = 2 + 3j  # an expression adding 2 to 3j
    z = 5*3j  # an expression multiplying 5 by 3j

There's no need for dedicated syntax for complex numbers beyond the 
simple no-real-part case. You get everything else for free from basic 
arithmetic expressions, so there actually isn't need to parse complex 
literals beyond the j suffix.


"Should literals be parsed differently (or consistently) with correctly 
formed strings?" Once you decide that complex literals should be formed 
from only the imaginary part, 3j, parsing literals is simple. So is 
passing strings: you have something that looks like a float, with a j 
suffix. Obviously they should parse the same.

    assert 1.234j == complex('1.234j')

Problem solved.

Well, not quite -- it would be rather limiting if the complex constructor 
only accepted complex numbers with an implicitly zero real part. We'd 
like to accept anything that repr(z) can print. Since repr(z) prints 
complex numbers with a + or - infix operator, the complex constructor 
should accept the same inside strings.

How flexible should the complex constructor be? Should it bend over 
backwards to accept any mathematical expression that includes a complex j 
suffix, e.g. complex("2**3i")? I think not, since complex numbers don't 
display like that. Our only obligation is to parse the strings that 
complex.__repr__ can produce, not to parse any imaginable numeric 
expression.

So at a minimum, complex should accept strings that look like 

    <float>j
    <float>+<float>j 
    <float>-<float>j

For the same reason that float("2") works, we should also allow strings 
that look like:

    <float>

with no j suffix. Anything else, including spaces around the + and - 
symbols, would be a bonus.


> consider:
>  >>> complex( 3   +  2   j)
> SyntaxError: invalid syntax

That's a syntax error for the same reason that:

    x = 1   2

is a syntax error. Nothing to do with the + sign. It's the spaces between 
the 2 and the j.


>  >>> complex( 3   +2j  )
> (3+2j)
>  >>>
> I don't know... you tell me.

In both cases, the call to complex is redundant. You've already created a 
complex number, using syntax, then you pass it to the complex function 
which just returns the same number.


>  >>> complex('3+2j')
> (3+2j)
>  >>> complex('3 +2j')
> Traceback (most recent call last):
>    File "<pyshell#17>", line 1, in <module>
>      complex('3 +2j')
> ValueError: complex() arg is a malformed string


Personally, I would like complex to accept spaces around the + or -, as 
it already accepts leading and trailing spaces. But it's not a big deal.


[...]
> Also, philosophically, C ignores white space;  python does not.

C does not ignore whitespace. 

    forwhile

is not the same as

    for while


The first is a valid identifier, the second is a syntax error. Oh 
somebody please tell me it's not a valid C expression! *wink*



-- 
Steven


From rosuav at gmail.com  Tue Mar 18 00:59:56 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 15:59:56 +1100
Subject: 'complex' function with string argument.
In-Reply-To: <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CAPTjJmoT5y0Uo4a0_Wud15XM_9VHA6XyCC9dqi48W9Eoye3-Rg@mail.gmail.com>

On Tue, Mar 18, 2014 at 3:52 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> The first is a valid identifier, the second is a syntax error. Oh
> somebody please tell me it's not a valid C expression! *wink*

It's not a valid C expression.

ChrisA


From frank at chagford.com  Tue Mar 18 01:39:37 2014
From: frank at chagford.com (Frank Millman)
Date: Tue, 18 Mar 2014 07:39:37 +0200
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
Message-ID: <lg8m6b$c8t$1@ger.gmane.org>


"Chris Angelico" <rosuav at gmail.com> wrote in message 
news:CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g at mail.gmail.com...
> On Tue, Mar 18, 2014 at 12:06 AM, Frank Millman <frank at chagford.com> 
> wrote:
[...]
>>
>> So where should I install the SCM, and how should I set it up so that I 
>> can
>> access the latest version from any machine?
>
> First off: You can save yourself a huge amount of trouble now! Modern
> source control systems are distributed (DVCS - Distributed Version
> Control System), which means that you have a much simpler setup: every
> machine that uses it has a full clone of the repository.
>
> By the sound of it, you don't have any history at the moment, so I'll
> assume you just start using either git or hg from where you are. The
> first thing to do is to get a local copy of the current source tree.
> I'd start with a Linux system, because everything seems to be easier
> there...
>
[...]

Thanks, Chris. I appreciate the detailed explanation.

Two quick questions -

1. At present the source code is kept on one machine (A), but only accessed 
from the two other machines (B and C).

Does it make sense to create the central repository on A, but *not* install 
the SCM on A? Install separate copies of the SCM on B and C, and allow them 
both to set up their own clones. I only develop on B, so only B would 
'push', but both B and C would 'pull' to get the latest version.

2. Being a typical lazy programmer, I frequently go through the following 
cycle. I work on a section of code by editing it on B. Then I test it by 
running it on C. Instead of meticulously checking my code I let python find 
the errors, so I run it on C, it crashes with a traceback, I fix the error 
on B and rerun it on C until it is working to my satisfaction.

It seems that I will have to change my approach. Edit on B, 'push' on B, 
'pull' on C, run from C. It sounds more cumbersome, but maybe that is the 
price I have to pay.

Have I got those two right?

Thanks

Frank





From rosuav at gmail.com  Tue Mar 18 02:03:27 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 17:03:27 +1100
Subject: Question about Source Control
In-Reply-To: <lg8m6b$c8t$1@ger.gmane.org>
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
Message-ID: <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>

On Tue, Mar 18, 2014 at 4:39 PM, Frank Millman <frank at chagford.com> wrote:
> Two quick questions -
>
> 1. At present the source code is kept on one machine (A), but only accessed
> from the two other machines (B and C).
>
> Does it make sense to create the central repository on A, but *not* install
> the SCM on A? Install separate copies of the SCM on B and C, and allow them
> both to set up their own clones. I only develop on B, so only B would
> 'push', but both B and C would 'pull' to get the latest version.

I don't know about Mercurial, but with git, installing the software on
A lets it work more efficiently (otherwise it has to do all the work
remotely, ergo unnecessary traffic). Advantage of free software is
that you don't have to check license agreements - just go ahead,
install it everywhere. But if for some reason that would be a problem,
you can look into running it over basic SSH or something.

> 2. Being a typical lazy programmer, I frequently go through the following
> cycle. I work on a section of code by editing it on B. Then I test it by
> running it on C. Instead of meticulously checking my code I let python find
> the errors, so I run it on C, it crashes with a traceback, I fix the error
> on B and rerun it on C until it is working to my satisfaction.
>
> It seems that I will have to change my approach. Edit on B, 'push' on B,
> 'pull' on C, run from C. It sounds more cumbersome, but maybe that is the
> price I have to pay.
>
> Have I got those two right?

That would be the simplest to set up. But here are two alternatives:

1) My current setup for developing Gypsum involves development on
Sikorsky, on Linux, and everything gets tested there. Then every once
in a while, I pull changes to Traal, and test on Windows. If there's a
problem, that's a separate commit fixing a separate issue ("Implement
pause key handling" / "Fix pause key handling on Windows"). That works
fairly well when you can do >90% of your testing on your development
box.

2) At work, we had a system for rapid development across two machines,
pretty much how you're describing. To make that work, I wrote a
three-part rapid send/receive system: a daemon that runs on the dev
system, a client that runs on the test system and connects to the
daemon, and a triggering notification that runs on the dev and tells
the daemon to do its work. (That could be done with a process signal,
but I wanted to send it some parameters.) When the daemon gets
notified to send its stuff across, it writes out the full content of
all changed files (mangled somewhat because my boss was paranoid -
well, as far as I know he's still utterly paranoid, but he's not my
boss any more) to the socket connection, and the receiver plops them
onto the disk and SIGHUPs the appropriate processes to tell them to
reload code.

The second option takes some setting up, though I'd be happy to help
out with the code. But it's really easy to use. You shoot stuff across
to it and off it all goes. The way I described above, it's quite happy
to have multiple simultaneous clients, and it's happy for those
clients to be behind NAT - so you can run half a dozen VMs with
different configurations, and have them all get the code together. And
you can put the trigger into a makefile to be run at the end of some
other tasks, or have it do some sanity checking, or whatever you like.
Very flexible and powerful.

ChrisA


From frank at chagford.com  Tue Mar 18 02:42:13 2014
From: frank at chagford.com (Frank Millman)
Date: Tue, 18 Mar 2014 08:42:13 +0200
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
Message-ID: <lg8prm$gs0$1@ger.gmane.org>


"Chris Angelico" <rosuav at gmail.com> wrote in message 
news:CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ at mail.gmail.com...
> On Tue, Mar 18, 2014 at 4:39 PM, Frank Millman <frank at chagford.com> wrote:
>> Two quick questions -
>>
>> 1. At present the source code is kept on one machine (A), but only 
>> accessed
>> from the two other machines (B and C).
>>
>> Does it make sense to create the central repository on A, but *not* 
>> install
>> the SCM on A? Install separate copies of the SCM on B and C, and allow 
>> them
>> both to set up their own clones. I only develop on B, so only B would
>> 'push', but both B and C would 'pull' to get the latest version.
>
> I don't know about Mercurial, but with git, installing the software on
> A lets it work more efficiently (otherwise it has to do all the work
> remotely, ergo unnecessary traffic). Advantage of free software is
> that you don't have to check license agreements - just go ahead,
> install it everywhere. But if for some reason that would be a problem,
> you can look into running it over basic SSH or something.
>

Excuse my ignorance, but how does it actually work?

Do you set up some kind of client/server relationship, and if so, how do the 
clients (machines B and C) access the software on machine A?

I know that Mercurial can run its own web server, and clients can access it 
through http. It that what you are suggesting? That would be quite a change 
for me, as on my linux box I do all my work from the command line on a 
console.

These are the kind of stumbling blocks that prevented me from succeeding in 
my previous attempt. I have a vague recollection that I set it up on machine 
A, but then hit a problem because machines B and C both accessed the same 
directory, but with different names - on Windows, a mapped drive and on 
linux a mounted nfs directory. I had to provide a 'path' name to set up 
Mercurial in the first place, but I could not find one that suited both 
clients.

I feel that I have just not grasped the basics yet, so any assistance that 
puts me on the right path is appreciated.

Frank





From ben+python at benfinney.id.au  Tue Mar 18 02:47:51 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 18 Mar 2014 17:47:51 +1100
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <lg8prm$gs0$1@ger.gmane.org>
Message-ID: <85y508roiw.fsf@benfinney.id.au>

"Frank Millman" <frank at chagford.com> writes:

> I feel that I have just not grasped the basics yet, so any assistance that 
> puts me on the right path is appreciated.

Here is ?Hg Init?, a tutorial for Mercurial <URL:http://hginit.com/>.

(?source control? is not the most common term for this; what we're
talking about is a ?version control system?, or VCS. But some Git users
may disagree.)

-- 
 \         ?If nature has made any one thing less susceptible than all |
  `\    others of exclusive property, it is the action of the thinking |
_o__)                          power called an idea? ?Thomas Jefferson |
Ben Finney



From frank at chagford.com  Tue Mar 18 02:45:05 2014
From: frank at chagford.com (Frank Millman)
Date: Tue, 18 Mar 2014 08:45:05 +0200
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org>
 <BLU0-SMTP953C8572B5CA6374830E50917D0@phx.gbl>
Message-ID: <lg8q12$ic8$1@ger.gmane.org>


"Andriy Kornatskyy" <andriy.kornatskyy at live.com> wrote in message 
news:BLU0-SMTP953C8572B5CA6374830E50917D0 at phx.gbl...
> Frank,
>
> I would suggest start with an account on https://bitbucket.org. It 
> supports private repositories so you should be good there.
>
> From other hand you can setup own infrastructure for SCM, read more here:
> http://mindref.blogspot.com/2013/10/how-to-manage-git-or-mercurial.html
>

Thanks, Andriy.

I followed your link, which took me to another link which took me to 
RhodeCode - https://rhodecode.com/

It looks interesting. I wll investigate that and bitbucket further.

Frank





From auriocus at gmx.de  Tue Mar 18 03:04:44 2014
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Tue, 18 Mar 2014 08:04:44 +0100
Subject: 'complex' function with string argument.
In-Reply-To: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
Message-ID: <lg8r68$g5e$1@dont-email.me>

Am 15.03.14 17:26, schrieb Jayanth Koushik:
> This is regarding the inbuilt 'complex' function. The python docs
> say: "Note: When converting from a string, the string must not
> contain whitespace around the central + or - operator. For example,
> complex('1+2j') is fine, but complex('1 + 2j') raises ValueError."

It's funny that you ask this question exactly now; because I'm currently 
implementing a compiler for a small language that understands complex 
numbers. As others have explained, the basic issue is the question how 
to parse an expression like

	1+2i*3

is it "complex(1+2i) times 3" or is it sum of 1 and product of complex 
2i and 3? The answer that python does it by parsing imaginary literals 
and then combining them back using peephole optimization was helpful, 
thanks for that!

	Christian


From rosuav at gmail.com  Tue Mar 18 03:09:51 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 18:09:51 +1100
Subject: Question about Source Control
In-Reply-To: <lg8prm$gs0$1@ger.gmane.org>
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <lg8prm$gs0$1@ger.gmane.org>
Message-ID: <CAPTjJmqLa9-VW9dDROJC+h1ncjJ2uMqXNA84EyHXNZuRYtO6_g@mail.gmail.com>

On Tue, Mar 18, 2014 at 5:42 PM, Frank Millman <frank at chagford.com> wrote:
> Excuse my ignorance, but how does it actually work?

Ignorance not only excused, but welcomed. :) However, caveat: I know
how git is set up, but not hg. Someone else can fill in the details;
for now, I'll explain git and hope that hg is broadly similar. I
expect it will be.

> Do you set up some kind of client/server relationship, and if so, how do the
> clients (machines B and C) access the software on machine A?

For read-only access, git can run its own protocol, but for read/write
it's most common to run it over SSH. Every pull or push is implemented
by git calling on ssh to run either 'git send-pack' or 'git
receive-pack' on the other end. (It's common to set it up with a
restricted shell that can *only* run those commands, although I also
find this usage convenient for cloning between two computers that I
control, rather than fetching from upstream. It's immensely faster
downloading something over a virtualized gigabit ethernet link than
over the internet!)

So it goes by the rules of SSH. There's a user account on the target
computer, which owns all the files in the repository. That user
account might have a password on it (which you type in every time you
pull/push), or you might use public/private keys to authenticate, or
whatever else you've set up. That part isn't git's responsibility. On
Linux systems, it's usually pretty easy to set up openssh and a
dedicated account; on other servers, I assume it can't be hard to get
something going.

> I know that Mercurial can run its own web server, and clients can access it
> through http. It that what you are suggesting? That would be quite a change
> for me, as on my linux box I do all my work from the command line on a
> console.

You'd still do everything from the command line. You type "git clone
blahblah" or "hg clone blahblah", and everything happens under the
covers. The only way you'd know the difference is if the "blahblah"
part identifies the protocol (which it usually will, but that's
somewhat beside the point).

> These are the kind of stumbling blocks that prevented me from succeeding in
> my previous attempt. I have a vague recollection that I set it up on machine
> A, but then hit a problem because machines B and C both accessed the same
> directory, but with different names - on Windows, a mapped drive and on
> linux a mounted nfs directory. I had to provide a 'path' name to set up
> Mercurial in the first place, but I could not find one that suited both
> clients.
>
> I feel that I have just not grasped the basics yet, so any assistance that
> puts me on the right path is appreciated.

Yeah, a distributed repository solves that. You could have three
entirely different path names on the three computers, and nothing will
care. (You have to be careful to use relative paths everywhere
internally, of course, but you probably do that already.) It's pretty
efficient once you get used to it; I recommend poking around on the
internet for a git tutorial or an hg tutorial, depending on which you
go with. It's not too hard, but there are a lot of commands to keep
track of. Here's a helpful quick reference to the differences between
the two:

https://github.com/sympy/sympy/wiki/Git-hg-rosetta-stone

As a git-familiar and hg-novice, I keep that handy every time I'm
working with hg on anything more complicated than "keep up with the
changes".

ChrisA


From rosuav at gmail.com  Tue Mar 18 03:11:45 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 18:11:45 +1100
Subject: 'complex' function with string argument.
In-Reply-To: <lg8r68$g5e$1@dont-email.me>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg8r68$g5e$1@dont-email.me>
Message-ID: <CAPTjJmqkR8jHXuSowKNM3Z7OXaParD4uir-DruxxkSDvVdsp3Q@mail.gmail.com>

On Tue, Mar 18, 2014 at 6:04 PM, Christian Gollwitzer <auriocus at gmx.de> wrote:
> As others have explained, the basic issue is the question how to parse an
> expression like
>
>         1+2i*3
>
> is it "complex(1+2i) times 3" or is it sum of 1 and product of complex 2i
> and 3?

The only way to have it be the former would be to mandate that all
complex literals have both parts, and you'd still lose clarity. You'd
probably want to have some other symbol rather than + in there, to
emphasize the connection:

1_2j
1_--2j # Negative imaginary component

Otherwise, yeah, do what Python does and have imaginary literals only.

ChrisA


From frank at chagford.com  Tue Mar 18 03:14:28 2014
From: frank at chagford.com (Frank Millman)
Date: Tue, 18 Mar 2014 09:14:28 +0200
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <lg8prm$gs0$1@ger.gmane.org> <85y508roiw.fsf@benfinney.id.au>
Message-ID: <lg8ro3$57n$1@ger.gmane.org>


"Ben Finney" <ben+python at benfinney.id.au> wrote in message 
news:85y508roiw.fsf at benfinney.id.au...
> "Frank Millman" <frank at chagford.com> writes:
>
>> I feel that I have just not grasped the basics yet, so any assistance 
>> that
>> puts me on the right path is appreciated.
>
> Here is "Hg Init", a tutorial for Mercurial <URL:http://hginit.com/>.
>
> ("source control" is not the most common term for this; what we're
> talking about is a "version control system", or VCS. But some Git users
> may disagree.)
>

Thanks, Ben, that is a really nice tutorial.

I was calling it an SCM because that is how Mercurial describes it - from 
their home page "Mercurial is a free, distributed source managment control 
tool". I do agree that 'version control' makes more sense.

Frank





From rosuav at gmail.com  Tue Mar 18 03:18:20 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 18:18:20 +1100
Subject: Question about Source Control
In-Reply-To: <85y508roiw.fsf@benfinney.id.au>
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <lg8prm$gs0$1@ger.gmane.org> <85y508roiw.fsf@benfinney.id.au>
Message-ID: <CAPTjJmr2w8MK6N5yMvR8PQtQ69AvF3dyLu4FciHcSjXWNoofJQ@mail.gmail.com>

On Tue, Mar 18, 2014 at 5:47 PM, Ben Finney <ben+python at benfinney.id.au> wrote:
> (?source control? is not the most common term for this; what we're
> talking about is a ?version control system?, or VCS. But some Git users
> may disagree.)

People use different terms depending on their backgrounds, I think.
I've heard a good few words used to describe fundamentally the same
thing, and none is really perfect.

ChrisA


From usenetmail at solar-empire.de  Tue Mar 18 03:36:44 2014
From: usenetmail at solar-empire.de (Marc Christiansen)
Date: Tue, 18 Mar 2014 08:36:44 +0100
Subject: Ordering in the printout of a dictionary
References: <lg8462$fnk$1@news.albasani.net>
 <mailman.8231.1395103693.18130.python-list@python.org>
Message-ID: <cl9lva-45d.ln1@pluto.solar-empire.de>

Chris Angelico <rosuav at gmail.com> wrote:
> On Tue, Mar 18, 2014 at 11:32 AM, Mok-Kong Shen
> <mok-kong.shen at t-online.de> wrote:
>> Is there a way to force a certain ordering of the printout or else
>> somehow manage to get at least a certain stable ordering of the
>> printout (i.e. input and output are identical)?
> 
> Yes; instead of simply printing it out (which calls repr()),
> explicitly iterate over it, like this:
> 
> def display(d):
>    return '{'+','.join('%r: %r'%(key,d[key]) for key in sorted(d))+'}'
> 
[...]
> At least, it's consistent as long as the keys all sort consistently,
> which they will if you use simple strings. Other types of keys may not
> work, and in fact mixing types may cause an exception:
> 
>>>> print(display({True:1,"Hello":2}))
> Traceback (most recent call last):
>  File "<stdin>", line 1, in <module>
>  File "<stdin>", line 2, in display
> TypeError: unorderable types: str() < bool()
> 
> But for strings, this is the easiest way to get what you're looking for.

I would say using pprint.pprint is even easier and it works with your
failing example:

>>> pprint.pprint({True:1,"Hello":2})
{True: 1, 'Hello': 2}

Ciao
Marc


From joshua at landau.ws  Tue Mar 18 03:46:42 2014
From: joshua at landau.ws (Joshua Landau)
Date: Tue, 18 Mar 2014 07:46:42 +0000
Subject: Balanced trees
In-Reply-To: <CAMMy=OveYrvz+SZkbk9WvdrmsQMEx3_HVWSkcatbZC4A5jzD8Q@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <CAN1F8qU=2K6ysbpnu-JoUtfWfTToRsOaRek0dSQzjPx_sYzPKQ@mail.gmail.com>
 <CAMMy=OsYUzULRTRHwytiTszd44f3anz43=2DtGALHR3nBGe8JQ@mail.gmail.com>
 <CAN1F8qUqVnhjxXEUnub36GEwK_DD+ukKK2GwA5wYku0s=wpdgA@mail.gmail.com>
 <CAMMy=OveYrvz+SZkbk9WvdrmsQMEx3_HVWSkcatbZC4A5jzD8Q@mail.gmail.com>
Message-ID: <CAN1F8qX3b6n=sGTNcnm=VxwfOOFD3qVp=v9_cMEHU0ND+dJr3g@mail.gmail.com>

On 18 March 2014 01:01, Daniel Stutzbach <stutzbach at google.com> wrote:
> I would love to have include macro-benchmarks.  I keep waiting for the PyPy
> benchmark suite to get ported to Python 3...

*grins*

>> "Delete a slice" is fudged from its inclusion of multiplication, which
>> is far faster on blists. I admit that it's not obvious how to fix
>> this.
>
> I could move the initialization into the timed part, similar to what I did
> for sort (see below).  That has downsides too, of course, but it might be an
> improvement.

You could try making a baseline and subtracting it:

    timer("del x[len(x)//4:3*len(x)//4]; x *= 2") - timer("x * 2")

Not ideal, but closer, assuming that the multiplication isn't much
larger than the deletion. Error would be summed.

>> "Sort *" are really unfair because they put initialisation in the
>> timed part
>
> That's a limitation of timeit.  The setup step is only executed once.  If I
> put the initialization there, every sort after the first one would be
> sorting a pre-sorted list.  If you compare the "Create form an iterator" and
> "Sort a random list", you'll see that the initialization cost is dwarfed by
> the sorting cost for n > 15 or so.

This argument is slightly less convincing without the overhead of the
keys. It might be worth doing a subtraction and adding some error-bars
as I suggest above. Nevertheless, I do agree for n > some small n,
which is all that matters anyway.

>> and all have keys.
>
> If you use classes with __lt__ methods instead of keys, the cost is
> dominated by the calls to __lt__.  You're right that I should include both,
> though.

This argument doesn't make sense to me. The only time this happens is
when you have a non-primitive and your transformation gives a
primitive which has optimised comparisons. This typically only happens
when the key is a getitem or getattr, in which case it's just
meaningless overhead. I see little reason to care about the key's cost
in those cases.

> That's definitely a cache issue, which is always a risk with
> micro-benchmarks.
>
> I agree it's more interesting to pick items randomly instead of always
> querying the same index.  The overhead of choice() is kind of a problem,
> though.  Since I'm only plotting up to 10**5, I'd expect these to look more
> or less flat.

You could try jumping around to avoid the cache without using random
numbers. Something like "idx = (idx + LARGE_PRIME) % n" might have less
overhead. Further, the subtraction method would probably work fine for
that.

Also, I don't think the cache is all bad. Chances are a lot of list
accesses have a lot of data locality.

> Thanks for all of the feedback.

Thanks in turn for the module :).


From rosuav at gmail.com  Tue Mar 18 03:55:17 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 18:55:17 +1100
Subject: Ordering in the printout of a dictionary
In-Reply-To: <cl9lva-45d.ln1@pluto.solar-empire.de>
References: <lg8462$fnk$1@news.albasani.net>
 <mailman.8231.1395103693.18130.python-list@python.org>
 <cl9lva-45d.ln1@pluto.solar-empire.de>
Message-ID: <CAPTjJmqUUyTNUfyNfM7oi1R=nf0aYvWMbejTyqhrc8Q1FLxHbQ@mail.gmail.com>

On Tue, Mar 18, 2014 at 6:36 PM, Marc Christiansen
<usenetmail at solar-empire.de> wrote:
> I would say using pprint.pprint is even easier and it works with your
> failing example:
>
>>>> pprint.pprint({True:1,"Hello":2})
> {True: 1, 'Hello': 2}
>

True. I could try to say that I prefer to offer the simpler approach
rather than encourage people to automatically reach for the nearest
hammer and hope it's right, but the fact is... I completely forgot
about pprint :)

ChrisA


From steve at pearwood.info  Tue Mar 18 03:55:51 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 18 Mar 2014 07:55:51 GMT
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <lg8prm$gs0$1@ger.gmane.org>
 <mailman.8239.1395125283.18130.python-list@python.org>
Message-ID: <5327fc07$0$2923$c3e8da3$76491128@news.astraweb.com>

On Tue, 18 Mar 2014 17:47:51 +1100, Ben Finney wrote:

> "Frank Millman" <frank at chagford.com> writes:
> 
>> I feel that I have just not grasped the basics yet, so any assistance
>> that puts me on the right path is appreciated.
> 
> Here is ?Hg Init?, a tutorial for Mercurial <URL:http://hginit.com/>.
> 
> (?source control? is not the most common term for this; what we're
> talking about is a ?version control system?, or VCS. But some Git users
> may disagree.)

I don't think that *version* control is the right model to describe what 
hg and git do, although it may be appropriate for subversion. hg doesn't 
manage *versions*, it manages changes to source code ("changesets"). 
Mercurial describes itself as a "distributed source control management 
tool", so I think the term "source control" is quite appropriate.

http://mercurial.selenic.com/


-- 
Steve


From steve at pearwood.info  Tue Mar 18 04:00:29 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 18 Mar 2014 08:00:29 GMT
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg8r68$g5e$1@dont-email.me>
Message-ID: <5327fd1c$0$2923$c3e8da3$76491128@news.astraweb.com>

On Tue, 18 Mar 2014 08:04:44 +0100, Christian Gollwitzer wrote:

> Am 15.03.14 17:26, schrieb Jayanth Koushik:
>> This is regarding the inbuilt 'complex' function. The python docs say:
>> "Note: When converting from a string, the string must not contain
>> whitespace around the central + or - operator. For example,
>> complex('1+2j') is fine, but complex('1 + 2j') raises ValueError."
> 
> It's funny that you ask this question exactly now; because I'm currently
> implementing a compiler for a small language that understands complex
> numbers. As others have explained, the basic issue is the question how
> to parse an expression like
> 
> 	1+2i*3
> 
> is it "complex(1+2i) times 3" 

Putting my mathematician's hat on, I would say *absolutely not*.

> or is it sum of 1 and product of complex 2i and 3? 

This one. Multiplication has higher precedence than addition, so 1+2i*3 
has to be evaluated as 1+(2i*3).


-- 
Steve


From rosuav at gmail.com  Tue Mar 18 04:08:17 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 19:08:17 +1100
Subject: Question about Source Control
In-Reply-To: <5327fc07$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <lg8prm$gs0$1@ger.gmane.org>
 <mailman.8239.1395125283.18130.python-list@python.org>
 <5327fc07$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CAPTjJmr-NmrVRePwQ6BkAWuDX5UD51tUj1iokwxf3uSMBipWLQ@mail.gmail.com>

On Tue, Mar 18, 2014 at 6:55 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> I don't think that *version* control is the right model to describe what
> hg and git do, although it may be appropriate for subversion. hg doesn't
> manage *versions*, it manages changes to source code ("changesets").

Meh... Is there any real difference? With git, I can check out any
tree state I like ("give me the 50th parent of the current HEAD"), so
in that sense it effectively stores versions - at least, it can
retrieve or recreate versions. Does it store versions and optimize
them by recording only the difference, or record differences and
replay them to recreate a state? Two sides of the same coin.

ChrisA


From auriocus at gmx.de  Tue Mar 18 04:21:48 2014
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Tue, 18 Mar 2014 09:21:48 +0100
Subject: 'complex' function with string argument.
In-Reply-To: <5327fd1c$0$2923$c3e8da3$76491128@news.astraweb.com>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>	<lg8r68$g5e$1@dont-email.me>
 <5327fd1c$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <lg8vmn$929$1@dont-email.me>

Hi Steven,

Am 18.03.14 09:00, schrieb Steven D'Aprano:
> On Tue, 18 Mar 2014 08:04:44 +0100, Christian Gollwitzer wrote:
>
>> Am 15.03.14 17:26, schrieb Jayanth Koushik:
>>> This is regarding the inbuilt 'complex' function. The python docs say:
>>> "Note: When converting from a string, the string must not contain
>>> whitespace around the central + or - operator. For example,
>>> complex('1+2j') is fine, but complex('1 + 2j') raises ValueError."
>>
>> It's funny that you ask this question exactly now; because I'm currently
>> implementing a compiler for a small language that understands complex
>> numbers. As others have explained, the basic issue is the question how
>> to parse an expression like
>>
>> 	1+2i*3
>>
>> is it "complex(1+2i) times 3"
>
> Putting my mathematician's hat on, I would say *absolutely not*.
>
>> or is it sum of 1 and product of complex 2i and 3?
>
> This one. Multiplication has higher precedence than addition, so 1+2i*3
> has to be evaluated as 1+(2i*3).

The question was not whether the expression should be interpreted the 
first way, I'm sorry for being unclear. The question was how to 
implement this in a compiler. Because if you implement complex literals 
in the tokenizer, you would end up with the tokens of the first 
interpretation. But if you implement as imaginary literals, then your 
parse tree for "1+2i" ends up as a sum of a real and an imaginary 
literal, instead of a complex literal. This works, but it lets your 
parse tree grow and possibly generates inefficient code. The answer I 
got here, is to parse it as a sum and let the optimizer combine it back 
into a single complex constant.


The same problem arises with unary minus, but it's less annoying because 
-(a*b) = (-a)*b.

I admit that my knowledge of compiler construction is limited, and I'm 
working on my first real-world application now. Oh, and it's not written 
in Python.

	Christian




From rosuav at gmail.com  Mon Mar 17 23:48:52 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 18 Mar 2014 14:48:52 +1100
Subject: Venus / GuthVenus for iPhone, Nexus, Droid and Android Jelly Bean
In-Reply-To: <lg8ff4$lgr$1@dont-email.me>
References: <32cfed4b-dd74-4360-baab-03f6dba01bdb@googlegroups.com>
 <cf25883a-f4c9-4b41-ba2b-dc8d4db942e1@googlegroups.com>
 <71ab5220-6d5d-46bf-b33a-16aae6c87109@googlegroups.com>
 <MPG.2d91424e2332741598968f@news.eternal-september.org>
 <lg8ff4$lgr$1@dont-email.me>
Message-ID: <CAPTjJmqmFaGP7dc5SpDQXSoc38tPfGWWKdUC49JBFRJFL9yUeQ@mail.gmail.com>

On Tue, Mar 18, 2014 at 2:45 PM, Brad Guth <bradguth at yahoo.com> wrote:
> You may want to revise that manifesto to read 'suffer and pay dearly'
> instead of "GOING TO DIE", unless you meant via natural causes.

Don't bother responding to Thrinaxodon, it's a spammer.

ChrisA


From jsutar at gmail.com  Tue Mar 18 05:11:19 2014
From: jsutar at gmail.com (Jignesh Sutar)
Date: Tue, 18 Mar 2014 09:11:19 +0000
Subject: Find and replace multiple RegEx search expressions
Message-ID: <CACvW2fzS7xAa9JB3rQmRU6V9tiFJADhJFWcs-muTEjSB7wx6KA@mail.gmail.com>

Hi,

I'm trying to delete contents of a .txt log file, matching on multiple
re.sub criteria but not sure how to achieve this.

Below is an illustration of what I am trying to achieve (of course in this
example I can combine the 3 re.sub into a single re expression but my
actual code will have a dozen plus expression I need to match on so easier
to keep them separate). Only the last re.sub will take effect in the
example below I need all 3 to take effect.


import re
o = open(r"c:\temp\outputfile.txt","w")
data = open(r"C:\Temp\infile.txt").read()
o.write( re.sub(".*<X>     ","",data) )
o.write( re.sub(".*<Y>     ","",data) )
o.write( re.sub(".*<Z>     ","",data) )
o.close()


Thanks in advance.
Jignesh
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From __peter__ at web.de  Tue Mar 18 05:48:03 2014
From: __peter__ at web.de (Peter Otten)
Date: Tue, 18 Mar 2014 10:48:03 +0100
Subject: Find and replace multiple RegEx search expressions
References: <CACvW2fzS7xAa9JB3rQmRU6V9tiFJADhJFWcs-muTEjSB7wx6KA@mail.gmail.com>
Message-ID: <lg94o4$a6c$1@ger.gmane.org>

Jignesh Sutar wrote:

> Hi,
> 
> I'm trying to delete contents of a .txt log file, matching on multiple
> re.sub criteria but not sure how to achieve this.
> 
> Below is an illustration of what I am trying to achieve (of course in this
> example I can combine the 3 re.sub into a single re expression but my
> actual code will have a dozen plus expression I need to match on so easier
> to keep them separate). Only the last re.sub will take effect in the
> example below I need all 3 to take effect.
> 
> 
> import re
> o = open(r"c:\temp\outputfile.txt","w")
> data = open(r"C:\Temp\infile.txt").read()
> o.write( re.sub(".*<X>     ","",data) )
> o.write( re.sub(".*<Y>     ","",data) )
> o.write( re.sub(".*<Z>     ","",data) )
> o.close()

Apply all substitutions to data before you write the result to the file:

with open(infile) as f:
    data = f.read()

for expr in list_of_regexes:
    data = re.sub(expr, "", data)

with open(outfile, "w") as f:
    f.write(data)




From balajimarisetti at gmail.com  Tue Mar 18 06:10:58 2014
From: balajimarisetti at gmail.com (balaji marisetti)
Date: Tue, 18 Mar 2014 15:40:58 +0530
Subject: Python3 html.parser
Message-ID: <CAKcrOwejRS1Aptqoph=78mARm3mO2gBPq3Q1Mh=XyrbmB87JAg@mail.gmail.com>

Hi,

I'm trying to parse a pice of HTML code using `html.parser` in Python3.
I want to find out the offset of a particular end tag (let's say </p>) and
then stop processing
the remaining HTML code immediately. So I wrote something like this.

[code]
def handle_endtag(self, tag):
    if tag == mytag:
        #do something
        self.reset()
[code]

I called `reset()` method at the end of  `handle_endtag()` method. Now the
problem is: when I call parser.feed("some html"), it's giving an
"AssertionError" exception. Isn't the `reset()` method
supposed to be called inside "handler" methods?

Thanks,
Balaji
-- 
:-)balaji
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From __peter__ at web.de  Tue Mar 18 07:44:24 2014
From: __peter__ at web.de (Peter Otten)
Date: Tue, 18 Mar 2014 12:44:24 +0100
Subject: Python3 html.parser
References: <CAKcrOwejRS1Aptqoph=78mARm3mO2gBPq3Q1Mh=XyrbmB87JAg@mail.gmail.com>
Message-ID: <lg9bi9$v1b$1@ger.gmane.org>

balaji marisetti wrote:

> Hi,
> 
> I'm trying to parse a pice of HTML code using `html.parser` in Python3.
> I want to find out the offset of a particular end tag (let's say </p>) and
> then stop processing
> the remaining HTML code immediately. So I wrote something like this.
> 
> [code]
> def handle_endtag(self, tag):
>     if tag == mytag:
>         #do something
>         self.reset()
> [code]
> 
> I called `reset()` method at the end of  `handle_endtag()` method. Now the
> problem is: when I call parser.feed("some html"), it's giving an
> "AssertionError" exception. Isn't the `reset()` method
> supposed to be called inside "handler" methods?

Obviously not ;) After looking into the code I think there is no controlled 
way to stop parsing. I suggest that you raise a custom exception instead:

import html.parser

class TagFound(Exception):
    pass

class MyParser(html.parser.HTMLParser):
    def handle_endtag(self, tag):
        if tag == wanted_tag:
            raise TagFound

wanted_tag = "a"
parser = MyParser()
for data in ["<html><body><a></a></body></html>",
             "<html><body><b></b></body></html>"]:
    try:
        parser.feed(data)
    except TagFound:
        print("tag {!r} found".format(wanted_tag))
    else:
        print("tag {!r} not found".format(wanted_tag))
    parser.reset()




From steve+comp.lang.python at pearwood.info  Tue Mar 18 09:45:18 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 18 Mar 2014 13:45:18 GMT
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <lg8prm$gs0$1@ger.gmane.org>
 <mailman.8239.1395125283.18130.python-list@python.org>
 <5327fc07$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.8247.1395130100.18130.python-list@python.org>
Message-ID: <53284dee$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 18 Mar 2014 19:08:17 +1100, Chris Angelico wrote:

> On Tue, Mar 18, 2014 at 6:55 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> I don't think that *version* control is the right model to describe
>> what hg and git do, although it may be appropriate for subversion. hg
>> doesn't manage *versions*, it manages changes to source code
>> ("changesets").
> 
> Meh... Is there any real difference? 

If you believe Joel Spolsky, there is:

http://hginit.com/00.html

Scroll down about half way, to the section titled "One more big 
conceptual difference".

Recording *snapshots* versus recording *diffs* makes a considerable 
difference when it comes to dealing with merge conflicts.



-- 
Steven


From marko at pacujo.net  Tue Mar 18 10:00:13 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 18 Mar 2014 16:00:13 +0200
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg8r68$g5e$1@dont-email.me>
 <5327fd1c$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg8vmn$929$1@dont-email.me>
Message-ID: <87lhw738uq.fsf@elektro.pacujo.net>

Christian Gollwitzer <auriocus at gmx.de>:

> The same problem arises with unary minus, but it's less annoying
> because -(a*b) = (-a)*b.

  >>> -1**2
  -1


Marko


From steve+comp.lang.python at pearwood.info  Tue Mar 18 10:20:07 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 18 Mar 2014 14:20:07 GMT
Subject: Unexpected comparisons in dict lookup
Message-ID: <53285617$0$29994$c3e8da3$5496439d@news.astraweb.com>

I stumbled across this unexpected behaviour with Python 2.7 and 3.3. When 
you look up a key in a dict, the key is sometimes compared against other 
keys twice instead of just once.

First, a class that reports when it is being tested for equality, with a 
fixed hash so that we get collisions inside the dict:

class Spam:
    def __init__(self, label):
        self.label = label
    def __str__(self):
        return self.label
    def __hash__(self):
        return 100
    def __eq__(self, other):
        print("comparing %s with %s" % (self, other))
        return self is other


Create a dict and prepare for collisions:

x = Spam("x")
y = Spam("y")
d = {100: 1}  # hash(100) == 100


When we add x to the dict, it collides with the existing key 100, so I 
expect one call to Spam.__eq__, and that's exactly what I get:

py> d[x] = 200
comparing x with 100


But when I try adding y to the dict, it collides with 100, then it 
collides with x, then it apparently collides with x a second time:

py> d[y] = 300
comparing y with 100
comparing x with y
comparing x with y


I expected only two calls to __eq__, not three: first comparing with 100, 
then comparing with x. Checking for keys gives the same result:

py> x in d
comparing x with 100
True
py> y in d
comparing y with 100
comparing x with y
comparing x with y
True


What's more, checking for a key which is not present also compares three 
times instead of twice:

py> Spam("z") in d
comparing z with 100
comparing x with z
comparing x with z
comparing y with z
False


I expected it to compare z with 100, then x *once*, then y, then return 
False.

Why is the dict lookup comparing against x twice? It doesn't seem to be 
the fault of x. If I create a slightly different dict, with the 
collisions in a different order:

py> e = {x: 100}
py> e[100] = 200
comparing x with 100
py> e[y] = 300
comparing x with y
comparing y with 100
comparing y with 100



-- 
Steven


From harrismh777 at gmail.com  Tue Mar 18 12:14:49 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 18 Mar 2014 11:14:49 -0500
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>	<lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
Message-ID: <lg9rdm$us9$1@speranza.aioe.org>

On 3/17/14 11:52 PM, Steven D'Aprano wrote:
> On Mon, 17 Mar 2014 11:18:56 -0500, Mark H Harris wrote:
>>  Who knows, beats me.

> With respect, that's just because you would make a lousy language
> designer :-)

    Ouch    ;-)

> "How should one spell a complex number?" There is perfectly good syntax
> for complex numbers used by mathematicians and engineers for over a
> century. There is no need to invent something different just for the sake
> of being different:
>      Yes:   2+3i or 2+3j

    Yes.  my Q was rhetorical only. And for the sake of discussion, 
particularly on the part of the OP, to think about what one expects 
based on experience and common sense, as a mathematician. (that doesn't 
mean it will be easy for the lexical parser.

> "Should we use i or j ?" There are good reasons for both i and j. This
> one comes down to personal preference.

    no, not really.  nobody writes,   e^(jPI) + 1 = 0

    Euler wants to see   e^(iPI) + 1 = 0      ;-)

> "Should the imaginary part be set off somehow?" What do you mean "set
> off"? Why do you want to? Since the imaginary part can appear on its own:

    simply, is 2j a literal complex part?  ...yes     2 j  ...no

    In other words, there must NEVER be a space between the 2 and j. 
This is debatable:   3 +2j    although, I want to see    3+2j


>      z = 2 + 3j  # an expression adding 2 to 3j
>      z = 5*3j  # an expression multiplying 5 by 3j

    all good, well until its not

> How flexible should the complex constructor be? Should it bend over
> backwards to accept any mathematical expression that includes a complex j
> suffix, e.g. complex("2**3i")? I think not,

    I think not either.  But, it is possible to have *many* constructors/

    But, really, how often is this a problem?   like almost never!

>>   >>>  complex( 3   +2j  )
>> (3+2j)
>>   >>>
>> I don't know... you tell me.
>
> In both cases, the call to complex is redundant. You've already created a
> complex number, using syntax, then you pass it to the complex function
> which just returns the same number.

    Of course.  I was merely pointing out that the constructor for 
'literals' (whatever you guys mean by that) is 'different' than the 
consistency with the string constructor.  As Chris pointed out these are 
two markedly different animals; one is a valid parse syntax, the other 
is a string constructor.   But here is my point--- to the user the 
difference comes down to semantics, which is not really true.

     cf. below

>>   >>>  complex('3+2j')
>> (3+2j)
>>   >>>  complex('3 +2j')
>> Traceback (most recent call last):
>>     File "<pyshell#17>", line 1, in<module>
>>       complex('3 +2j')
>> ValueError: complex() arg is a malformed string


>> Also, philosophically, C ignores white space;  python does not.

    This was said tongue in cheek...  *both* languages inconsistently 
observer (and ignore) white space!  But, in general, white space is more 
important to python, and less important to C.

I'm still hung up on whether I'm a lousy language designer.  I guess 
we'll know if people use my language (or not)!  I suppose they might use 
it even though its lousy; on the other hand, it might be too simple for 
folks to be able to figure it out.   :)

marcus


From nospam at thanks.invalid  Tue Mar 18 12:17:36 2014
From: nospam at thanks.invalid (Juha Nieminen)
Date: Tue, 18 Mar 2014 16:17:36 +0000 (UTC)
Subject: HOLY SH*T! HUMANS ORIGINATED IN THE DEVONIAN
References: <MPG.2d90815744d89924989689@news.eternal-september.org>
Message-ID: <lg9rit$80i$1@adenine.netfront.net>

In comp.lang.c++ ASSODON <troll at bitch.invalid> wrote:
> THRINAXODON DANCED WITH JOY AS HE WAS GRANTED $600,000,000,000.000!

I find it interesting, from a psychological perspective, that you are
not even *pretending* that you are not lying and making stuff up.
You pretty much imply it as clearly as it possibly can be, and clearly
don't care. Yet, nevertheless, you accuse others of lying.

I don't think you are simply a troll who does this for his own amusement,
because even trolls get tired of the same old joke, and move to other
things. I get a feeling of this being more obsessive in nature.

There's something probably very wrong inside your head. I really think
you should seek professional help for your mental problems.

--- news://freenews.netfront.net/ - complaints: news at netfront.net ---


From ladynikon at gmail.com  Tue Mar 18 12:56:03 2014
From: ladynikon at gmail.com (Danyelle Davis)
Date: Tue, 18 Mar 2014 12:56:03 -0400
Subject: HOLY SH*T! HUMANS ORIGINATED IN THE DEVONIAN
In-Reply-To: <MPG.2d90815744d89924989689@news.eternal-september.org>
References: <MPG.2d90815744d89924989689@news.eternal-september.org>
Message-ID: <CAO32GkBnNHq=w9NAvuZDk3OaN65+SW+JBT_pOD_-coxSY3ANNQ@mail.gmail.com>

Don't feed the trolls.  Actually talking to it makes it think you actually
care..


On Mon, Mar 17, 2014 at 4:50 AM, ASSODON <troll at bitch.invalid> wrote:

> =======================
> >BREAKING NEWSSSSSSSSS
> =======================
> >
> RICHARD LEAKEY JUST DIED DUE TO HEART FAILURE!
> >
> THE REASONS DESCRIBED BY THE MEDICAL TEAM IS THAT HIS WORK WAS
> DISPROVEN, BY NONE OTHER THAN YOUR OWN BASTARD, THRINAXODON.
> >
> THIS CAUSED LEAKEY'S HEART TO EXPLODE!
> >
> THRINAXODON DANCED WITH JOY AS HE WAS GRANTED $600,000,000,000.000!
> >
> TO WASTE YOUR TIME EVEN FURTHER, CHECK OUT THESE LINKS BELOW.
> ===========================
> EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:
>
> https://groups.google.com/group/sci.bio.paleontology/browse_thread/threa
> d/6f501c469c7af24f#
>
>
> https://groups.google.com/group/sci.bio.paleontology/browse_thread/threa
> d/3aad75c16afb0b82#
>
>
> ====================================
>
> http://thrinaxodon.wordpress.com/
>
> ===================================
>
> THRINAXODON ONLY HAD THIS TO SAY:
>
> "I..I...I...Can't believe it. This completely disproved Darwinian
> orthodoxy."
>
> ===================================
>
> THE BASTARDS AT THE SMITHSONIAN, AND THE LEAKEY FOUNDATION ARE ERODING
> WITH FEAR.
>
> ===========================
> THESE ASSHOLES ARE GOING TO DIE:
> THOMAS AQUINAS;
> ALDOUS HUXLEY;
> BOB CASANVOVA;
> SkyEyes;
> DAVID IAIN GRIEG;
> MARK ISAAK;
> JOHN HARSHAM;
> RICHARD NORMAN;
> DR. DOOLITTLE;
> CHARLES DARWIN;
> MARK HORTON;
> ERIK SIMPSON;
> HYPATIAB7;
> PAUL J. GANS;
> JILLERY;
> WIKI TRIK;
> THRINAXODON;
> PETER NYIKOS;
> RON OKIMOTO;
> JOHN S. WILKINS
> ===========================
>
> THRINAXODON WAS SCOURING ANOTHER DEVONIAN FOSSIL BED, AND FOUND A
> HUMAN SKULL, AND A HUMAN FEMUR. HE ANALYSED THE FINDS, AND SAW THAT
> THEY WERE NOT NORMAL ROCKS. THESE WERE FOSSILIZED BONES. THEY EVEN HAD
> TOOTH MARKS ON THEM. SO, THRINAXODON BROUGHT THEM TO THE LEAKEY
> FOUNDATION, THEY UTTERLY DISMISSED IT, AND SAID, "We want to keep
> people thinking that humans evolved 2 Ma." THRINAXODON BROUGHT HIS
> SWORD, AND SAID, "SCIENCE CORRECTS ITSELF." RICHARD LEAKEY SAID, "That
> is a myth, for people to believe in science." THRINAXODON PLANS TO
> BRING DOOM TO SCIENCE, ITSELF.
>
> ============================
>
> THRINAXODON IS NOW ON REDDIT
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>
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From jabba.laci at gmail.com  Tue Mar 18 13:03:26 2014
From: jabba.laci at gmail.com (Jabba Laci)
Date: Tue, 18 Mar 2014 18:03:26 +0100
Subject: extract stream title from the output of mplayer
Message-ID: <CAOuJsM=ehKxRDmJ=2HXUCi6OZ8g0OBjQG87RQ+NWuCeBFKKedw@mail.gmail.com>

Hi,

I have a simple command-line radio player and I want to extract song
titles from the output of mplayer.

Example:

$ mplayer http://relay2.slayradio.org:8000/

It produces a streamed output of this form:

MPlayer2 UNKNOWN (C) 2000-2012 MPlayer Team
mplayer: could not connect to socket
mplayer: No such file or directory
...
ICY Info: StreamTitle='Alexander 'Taxim' Nev - Unsound minds feat.
SAM';StreamUrl='http://www.SLAYRadio.org/';
...

At the end it shows a progress indicator, thus the output is streamed.
The problem is I can't get this output in a string. My idea is to
launch mplayer with a timeout of 2 seconds for instance, get the
produced output and find the line that starts with "ICY Info". But
when I kill the process after the timeout, I don't know how to fetch
the output produced so far.

Thanks,

Laszlo


From harrismh777 at gmail.com  Tue Mar 18 13:03:40 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 18 Mar 2014 12:03:40 -0500
Subject: Question about Source Control
References: <mailman.8190.1395061611.18130.python-list@python.org>
Message-ID: <lg9u9a$7b2$1@speranza.aioe.org>

On 3/17/14 8:06 AM, Frank Millman wrote:
> All my source code resides on an old Linux server, which I switch on in the
> morning and switch off at night, but otherwise hardly ever look at. It uses
> 'samba' to allow sharing with Windows, and 'nfs' to allow sharing with other
> Linux machines.

hi Frank, I am using GIT and code.google.com.

    https://code.google.com/p/pythondecimallibrary/

    I have not used Code Google prior to the pdeclib project; however, I 
plan to use it in the future extensively, at least for my open source 
projects (and when I am thinking about bringing another person on board.

    Code Google permits three version|control|access systems (I use GIT, 
a very simple command line interface).  The thing is that the code 
resides on a person's machine as a clone of the repository, and is 
assessable from anywhere in the world, allows multiple developer 
participation, allows multiple branches|merge|master, and allows access 
to the source on-line (browse|edit), and permits new members to clone 
the repository from anywhere.  Downloads are zipped.

    The down-side is also the up-side. Code Google is an open source 
developer collaborative environment for sharing & managing. Anything you 
put there belongs to everyone in the project, and can be viewed by 
anyone in the world (which is kinda the point of open source).  There is 
a supreme benefit to having multiple eyes on the code. People maybe not 
even involved in the project directly will comment on the code (and they 
are not shy). You code will improve dynamically and radically (if you 
have the guts for it).

    It took me a couple of hours to get up to speed with Code Google. It 
took another hour or so to come up to speed with GIT. You need to create 
the project on Code Google first. Then on your machine, in the code 
directory (the directory actually holding the source files that you are 
going to make a part of your project) you do these things:

    git init
                    this builds the .git subdirectory needed for push

    git add file-name

                    add each filename you want to commit and push

    git remove

                    removes any unwanted files

    git commit -a

                    edit your commit comments here ,  or provide default


    git push  https://code.google.com/p/whateveryourprojectnameis/ master

                    sends the files on their way


    other files:    .gitconfig    .netrc


    You will place your name, email, and method (use simple) in the 
.gitconfig file.  The .netrc file will contain the login info for code 
google machine.


    Read the GIT manual on-line; its pretty easy too.

    https://www.kernel.org/pub/software/scm/git/docs/user-manual.html

    http://git-scm.com/documentation


Cheers





From rosuav at gmail.com  Tue Mar 18 13:12:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 19 Mar 2014 04:12:43 +1100
Subject: extract stream title from the output of mplayer
In-Reply-To: <CAOuJsM=ehKxRDmJ=2HXUCi6OZ8g0OBjQG87RQ+NWuCeBFKKedw@mail.gmail.com>
References: <CAOuJsM=ehKxRDmJ=2HXUCi6OZ8g0OBjQG87RQ+NWuCeBFKKedw@mail.gmail.com>
Message-ID: <CAPTjJmp7QYgW_6fsJ91-roGD-DwHD_s=s_HaD14SxvwrbiK9Aw@mail.gmail.com>

On Wed, Mar 19, 2014 at 4:03 AM, Jabba Laci <jabba.laci at gmail.com> wrote:
> I have a simple command-line radio player and I want to extract song
> titles from the output of mplayer.
>
> ICY Info: StreamTitle='Alexander 'Taxim' Nev - Unsound minds feat.
> SAM';StreamUrl='http://www.SLAYRadio.org/';
>
> At the end it shows a progress indicator, thus the output is streamed.
> The problem is I can't get this output in a string. My idea is to
> launch mplayer with a timeout of 2 seconds for instance, get the
> produced output and find the line that starts with "ICY Info". But
> when I kill the process after the timeout, I don't know how to fetch
> the output produced so far.

My first recommendation would be to see what you can get directly,
rather than calling on mplayer. But otherwise, what you want to do is
redirect the output somewhere. Are you using the Python subprocess
module to do this? You haven't shown any code, but since you posted
this to python-list I'm guessing that you probably are talking about
Python. (Or s/guess/hop/ if you prefer!) There are many ways this
could be done; what have you tried, what partly worked, what did
something unexpected?

ChrisA


From jabba.laci at gmail.com  Tue Mar 18 13:51:31 2014
From: jabba.laci at gmail.com (Jabba Laci)
Date: Tue, 18 Mar 2014 18:51:31 +0100
Subject: extract stream title from the output of mplayer
In-Reply-To: <CAPTjJmp7QYgW_6fsJ91-roGD-DwHD_s=s_HaD14SxvwrbiK9Aw@mail.gmail.com>
References: <CAOuJsM=ehKxRDmJ=2HXUCi6OZ8g0OBjQG87RQ+NWuCeBFKKedw@mail.gmail.com>
 <CAPTjJmp7QYgW_6fsJ91-roGD-DwHD_s=s_HaD14SxvwrbiK9Aw@mail.gmail.com>
Message-ID: <CAOuJsMkoGHkrHg6025TNE4G9Zc=dEBnUBuyBD_sGCFUdDEct7w@mail.gmail.com>

> Python. (Or s/guess/hop/ if you prefer!) There are many ways this
> could be done; what have you tried, what partly worked, what did
> something unexpected?

Hi,

I managed to solve the problem. In the man of mplayer I found how to
quit after X seconds: "-endpos X". See my solution below.

Best,

Laszlo

============

import re
import shlex
from subprocess import PIPE, Popen

URL = 'http://relay2.slayradio.org:8000/'


def get_exitcode_stdout_stderr(cmd):
    """
    Execute the external command and get its exitcode, stdout and stderr.
    """
    args = shlex.split(cmd)

    proc = Popen(args, stdout=PIPE, stderr=PIPE)
    out, err = proc.communicate()
    exitcode = proc.returncode
    #
    return exitcode, out, err


def get_title():
    cmd = "mplayer -endpos 1 -ao null {url}".format(url=URL)
    out = get_exitcode_stdout_stderr(cmd)[1]

    for line in out.split("\n"):
#        print(line)
        if line.startswith('ICY Info:'):
            match = re.search(r"StreamTitle='(.*)';StreamUrl=", line)
            title = match.group(1)
            return title

def main():
    print(get_title())


From drsalists at gmail.com  Tue Mar 18 15:26:09 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Tue, 18 Mar 2014 12:26:09 -0700
Subject: Balanced trees
In-Reply-To: <87mwgoqy4k.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
Message-ID: <CAGGBd_qDRdWQHVm-=qEfK8qKVdMsD8WjuPtDQ3nEaGia55SvrQ@mail.gmail.com>

On Mon, Mar 17, 2014 at 3:05 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Joshua Landau <joshua at landau.ws>:
>
>> The thing we really need is for the blist containers to become stdlib
>> (but not to replace the current list implementation).
>
> Very interesting. Downloaded blist but didn't compile it yet. It *could*
> be the missing link.
>
> I would *love* to see some comparative performance results between
> blist.sorteddict and an AVL tree.

I added blist.sorteddict and removed (temporarily) Pypy and Jython.
The results are at
http://stromberg.dnsalias.org/~strombrg/python-tree-and-heap-comparison/2014-03/

In short, blist.sorteddict didn't do that well, despite being in C.
In the random workloads, blist.sorteddict was dead last.  In the
sequential workloads blist.sorteddict fell somewhere in the middle.

I excluded Pypy and Jython because blist.sorteddict probably doesn't
run on them.

HTH


From ian.g.kelly at gmail.com  Tue Mar 18 16:15:31 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 18 Mar 2014 14:15:31 -0600
Subject: Unexpected comparisons in dict lookup
In-Reply-To: <53285617$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <53285617$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALwzidnaTfYFKA41Jsp9wwA1Vu7jY0xs5MFug-puzi7z+O+C2g@mail.gmail.com>

On Tue, Mar 18, 2014 at 8:20 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> I stumbled across this unexpected behaviour with Python 2.7 and 3.3. When
> you look up a key in a dict, the key is sometimes compared against other
> keys twice instead of just once.

>From what I can see in the code, it adds a perturbation based on the
upper bits of the hash value to the probing scheme, to reduce
collisions for keys with unequal hashes.  On the downside, this
cancels the guarantee that each bucket can only be checked at most
once.  The perturbation gradually shifts to 0 after a few iterations,
so every bucket can still be reached within O(n) iterations.

See the comments starting at "Major subtleties ahead":
http://hg.python.org/cpython/file/f8b40d33e45d/Objects/dictobject.c#l106


From stutzbach at google.com  Tue Mar 18 16:18:40 2014
From: stutzbach at google.com (Daniel Stutzbach)
Date: Tue, 18 Mar 2014 13:18:40 -0700
Subject: Balanced trees
In-Reply-To: <CAGGBd_qDRdWQHVm-=qEfK8qKVdMsD8WjuPtDQ3nEaGia55SvrQ@mail.gmail.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <CAGGBd_qDRdWQHVm-=qEfK8qKVdMsD8WjuPtDQ3nEaGia55SvrQ@mail.gmail.com>
Message-ID: <CAMMy=OuwTt7nEETRwDA23zxNxpJWzL6oG-0pSRYo8XmP0-vKbA@mail.gmail.com>

On Tue, Mar 18, 2014 at 12:26 PM, Dan Stromberg <drsalists at gmail.com> wrote:

> In short, blist.sorteddict didn't do that well, despite being in C.
>

blist.blist is written in C, but blist.sorteddict is written in Python on
top of blist.blist.  It won't perform as well as a class written entirely
in C that has similar asymptotic properties.  If the objects in the tree
are non-trivial (i.e., not a built-in type), the cost of calling the __lt__
method may be more important than the choice of blist vs. AVL tree, but I
haven't tested it.

-- 
Daniel Stutzbach
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From mitko.haralanov at intel.com  Tue Mar 18 16:23:19 2014
From: mitko.haralanov at intel.com (Haralanov, Mitko)
Date: Tue, 18 Mar 2014 20:23:19 +0000
Subject: Controlling buffer alignment in file.read()
Message-ID: <F5ED8E150D0FF14F82CAF3C46756763232396ECB@FMSMSX104.amr.corp.intel.com>

Hi all,

I am using Python to read from a binary device file which requires that all read sizes are in 8byte multiples and the user's buffer is 8byte aligned.

I am currently using a file object and the file.read() method. However, the issue is that the file.read() method allocates the buffer passed to C function under the covers and, therefore, the alignment is arbitrary.

Is there a way that I can get file.read() to use an 8byte aligned buffer?

Thanks,
- Mitko




From davea at davea.name  Tue Mar 18 16:51:41 2014
From: davea at davea.name (Dave Angel)
Date: Tue, 18 Mar 2014 16:51:41 -0400 (EDT)
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <lg8prm$gs0$1@ger.gmane.org>
 <mailman.8239.1395125283.18130.python-list@python.org>
 <5327fc07$0$2923$c3e8da3$76491128@news.astraweb.com>
 <mailman.8247.1395130100.18130.python-list@python.org>
 <53284dee$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgabbj$fnv$1@ger.gmane.org>

 Steven D'Aprano <steve+comp.lang.python at pearwood.info> Wrote in
 message:
> On Tue, 18 Mar 2014 19:08:17 +1100, Chris Angelico wrote:
> 
>> On Tue, Mar 18, 2014 at 6:55 PM, Steven D'Aprano <steve at pearwood.info>
>> wrote:
>>> I don't think that *version* control is the right model to describe
>>> what hg and git do, although it may be appropriate for subversion. hg
>>> doesn't manage *versions*, it manages changes to source code
>>> ("changesets").
>> 
>> Meh... Is there any real difference? 
> 
> If you believe Joel Spolsky, there is:
> 
> http://hginit.com/00.html
> 
> Scroll down about half way, to the section titled "One more big 
> conceptual difference".
> 
> Recording *snapshots* versus recording *diffs* makes a considerable 
> difference when it comes to dealing with merge conflicts.
> 

So which does git do, according to this model? 


-- 
DaveA



From marko at pacujo.net  Tue Mar 18 16:55:03 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 18 Mar 2014 22:55:03 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
Message-ID: <8738ifqlaw.fsf@elektro.pacujo.net>

Dan Stromberg <drsalists at gmail.com>:

> The results are at
> http://stromberg.dnsalias.org/~strombrg/python-tree-and-heap-comparison/2014-03/

Unfortunately I'm having a hard time understanding the results.

The 50/50 get/set ratio is most interesting to me.

I'm seeing (under cpython-3.3):


    Size: 1048576, duration:  75.3, dictionary type: dict
    [...]
    Size:  262144, duration:  66.1, dictionary type: AVL_tree
    [...]
    Size:   65536, duration:  77.3, dictionary type: blist.sorteddict 


What does it mean?


Marko


From klonuo at gmail.com  Tue Mar 18 17:04:46 2014
From: klonuo at gmail.com (klo uo)
Date: Tue, 18 Mar 2014 22:04:46 +0100
Subject: mobile friendly docs?
Message-ID: <CAA-8Ld8zYSm31KmK1t=uKFDLXj9cC04EEW4BSAA_myM8bpkHcw@mail.gmail.com>

Hi,

let me quickly introduce my concern - I was happy to see main
python.org portal rendered nicely on mobile, but docs are still hardly
accessible, while sphinx allows better experience if user instructs it
to.

So I browsed Python MLs (sorry if this is not the right one, I'd be
happy to forward my mail where you suggest) and wanted to ask if such
concern is planed, as I can run Python from years ago on my Nokias,
while feeling strange that official docs aren't accessible from
mobile.


TIA


From drsalists at gmail.com  Tue Mar 18 17:45:52 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Tue, 18 Mar 2014 14:45:52 -0700
Subject: Balanced trees
In-Reply-To: <8738ifqlaw.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
Message-ID: <CAGGBd_q_DgAkxX9utFPOVAbzCc+bdT2=OxDCLmqvDEbQRFYXMw@mail.gmail.com>

On Tue, Mar 18, 2014 at 1:55 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Dan Stromberg <drsalists at gmail.com>:
>
>> The results are at
>> http://stromberg.dnsalias.org/~strombrg/python-tree-and-heap-comparison/2014-03/
>
> Unfortunately I'm having a hard time understanding the results.
>
> The 50/50 get/set ratio is most interesting to me.
>
> I'm seeing (under cpython-3.3):
>
>
>     Size: 1048576, duration:  75.3, dictionary type: dict
>     [...]
>     Size:  262144, duration:  66.1, dictionary type: AVL_tree
>     [...]
>     Size:   65536, duration:  77.3, dictionary type: blist.sorteddict
>
>
> What does it mean?

dict was able to do 1048576 operations on a dictionary before taking
more than 120 seconds to complete - it took 75.3 seconds to do 1048576
operations.

AVL_tree was able to do 262144 operations on a dictionary before
taking more than 120 seconds to complete - it took 66.1 seconds to do
262144 operations.

blist.sorteddict was able to do 65536 operations on a dictionary
before taking more than 120 seconds to complete  - it took 77.3
seconds to do 65536 operations.

For the 50/50 workload; the "operations" were half adding key, value
pairs; and half lookups of values by keys we know are in the
dictionary.

I used to run all the dictionaries for as long as it took to do 4
million operations, but for (EG) unbalanced binary trees, that would
take far too long in the ordered tests, so I changed the code to try a
given tree type until the time for an operation became prohibitive.

If you look at the graphs (I have to admit they've become a little
cluttered), you can see the slower trees "escaping" rapidly (exceeding
the 120 second threshold), while the better performing trees grow more
slowly and are allowed to continue proving themselves longer.
Inspecting these graphs may help in developing an intuition for how
the tests were conducted.

The code implementing this method of testing is in
http://stromberg.dnsalias.org/svn/python-tree-and-heap-comparison/trunk/tester

HTH


From greg.ewing at canterbury.ac.nz  Tue Mar 18 17:51:22 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 19 Mar 2014 10:51:22 +1300
Subject: Question about Source Control
In-Reply-To: <mailman.8238.1395124947.18130.python-list@python.org>
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <mailman.8238.1395124947.18130.python-list@python.org>
Message-ID: <bortetF7t42U1@mid.individual.net>

Frank Millman wrote:
> These are the kind of stumbling blocks that prevented me from succeeding in 
> my previous attempt. I have a vague recollection that I set it up on machine 
> A, but then hit a problem because machines B and C both accessed the same 
> directory, but with different names

For dealing with your practice of editing on one machine and
running on another, you may be best off having just *one* local
repository, residing on the shared file system. Whichever machine
you're working on, you cd to the shared directory and use hg or
git commands from there, so all the pathnames you're using are
relative.

Source control operations might be slightly slower that way,
but you'd save time by not having to update your local repo
every time you switch between editing and running, so it may
well be faster overall. In any case, if the machines involved
are on a fast local network, I wouldn't expect there to be
much difference.

-- 
Greg


From marko at pacujo.net  Tue Mar 18 18:03:59 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 19 Mar 2014 00:03:59 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
Message-ID: <87wqfrp3jk.fsf@elektro.pacujo.net>

Dan Stromberg <drsalists at gmail.com>:

> dict was able to do 1048576 operations on a dictionary before taking
> more than 120 seconds to complete - it took 75.3 seconds to do 1048576
> operations.
>
> AVL_tree was able to do 262144 operations on a dictionary before
> taking more than 120 seconds to complete - it took 66.1 seconds to do
> 262144 operations.
>
> blist.sorteddict was able to do 65536 operations on a dictionary
> before taking more than 120 seconds to complete - it took 77.3 seconds
> to do 65536 operations.

For a proper comparison, I'd like a fixed, identical dataset and set of
operations run against each data structure.

How about this test program:

   generate random datasets of 100, 10000, 1000000 and 100000000 elements
   generate random testset of 1000000 elements
   for each data structure:
        for each dataset:
             initialize data structure with dataset
             head, tail = testset[:100], testset[100:]
             t0 = current timestamp
             for each element in head:
                  add element to data structure
             for each element in tail:
                  add element to data structure
                  append element to head
                  remove head.pop(0) from data structure
             for each element in head:
                  remove element from data structure
             t1 = current timestamp
             report data structure type, dataset size, t1 - t0


Marko


From drsalists at gmail.com  Tue Mar 18 18:21:28 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Tue, 18 Mar 2014 15:21:28 -0700
Subject: Balanced trees
In-Reply-To: <87wqfrp3jk.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
 <87wqfrp3jk.fsf@elektro.pacujo.net>
Message-ID: <CAGGBd_r1tYxaTntkjjk770cn5RBjbBrnUCURRndyK2bKo0L4Lw@mail.gmail.com>

On Tue, Mar 18, 2014 at 3:03 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Dan Stromberg <drsalists at gmail.com>:
> For a proper comparison, I'd like a fixed, identical dataset and set of
> operations run against each data structure.
>
> How about this test program:

I used to do essentially this, but it was time-prohibitive and
produced harder-to-read graphs - harder to read because the enormous
values of the bad trees were dwarfing the values of the good trees.

Imagine doing 100000000 operation tests for the unbalanced binary
tree. For a series of random keys, it would do quite well (probably
second only to dict), but for a series of sequential keys it would
take longer than anyone would reasonably want to wait because it's
basically a storage-inefficient linked list.

Rather than throw out unbalanced binary tree altogether, it makes more
sense to run it until it gets "too slow".

The workload+interpreter pairs are all tested the same way, it's just
that the ones that are doing badly are thrown out before they're able
to get a lot worse. Studying the graphs will likely help develop an
intuition for what's happening.


From greg.ewing at canterbury.ac.nz  Tue Mar 18 19:08:30 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 19 Mar 2014 12:08:30 +1300
Subject: Controlling buffer alignment in file.read()
In-Reply-To: <mailman.8260.1395174272.18130.python-list@python.org>
References: <mailman.8260.1395174272.18130.python-list@python.org>
Message-ID: <bos1vgF8r6oU1@mid.individual.net>

Haralanov, Mitko wrote:
> I am using Python to read from a binary device file which requires that all
> read sizes are in 8byte multiples and the user's buffer is 8byte aligned.
> 
> Is there a way that I can get file.read() to use an 8byte aligned buffer?

For control at that level you'd be better off using
direct system calls, i.e. os.open() and os.read(),
then you can read exacty the number of bytes you want.

-- 
Greg


From mitko.haralanov at intel.com  Tue Mar 18 19:13:46 2014
From: mitko.haralanov at intel.com (Haralanov, Mitko)
Date: Tue, 18 Mar 2014 23:13:46 +0000
Subject: Controlling buffer alignment in file.read()
In-Reply-To: <bos1vgF8r6oU1@mid.individual.net>
References: <mailman.8260.1395174272.18130.python-list@python.org>
 <bos1vgF8r6oU1@mid.individual.net>
Message-ID: <F5ED8E150D0FF14F82CAF3C467567632323980AF@FMSMSX104.amr.corp.intel.com>

> For control at that level you'd be better off using
> direct system calls, i.e. os.open() and os.read(),
> then you can read exacty the number of bytes you want.
> 

The problem is not controlling the number of bytes read. That part seems to be working.
The issue is that the buffer into which the data is placed needs to be of certain alignment (8byte-aligned). Python does not seem to have a way that allows me to control that.

Thanks,
- Mitko


From marko at pacujo.net  Tue Mar 18 19:11:33 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 19 Mar 2014 01:11:33 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
 <87wqfrp3jk.fsf@elektro.pacujo.net>
 <mailman.8264.1395181297.18130.python-list@python.org>
Message-ID: <87r45zf6fu.fsf@elektro.pacujo.net>

Dan Stromberg <drsalists at gmail.com>:

> On Tue, Mar 18, 2014 at 3:03 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> Dan Stromberg <drsalists at gmail.com>:
>> For a proper comparison, I'd like a fixed, identical dataset and set
>> of operations run against each data structure.
>>
>> How about this test program:
>
> I used to do essentially this, but it was time-prohibitive and
> produced harder-to-read graphs - harder to read because the enormous
> values of the bad trees were dwarfing the values of the good trees.
>
> Imagine doing 100000000 operation tests for the unbalanced binary
> tree. For a series of random keys, it would do quite well (probably
> second only to dict), but for a series of sequential keys it would
> take longer than anyone would reasonably want to wait because it's
> basically a storage-inefficient linked list.
>
> Rather than throw out unbalanced binary tree altogether, it makes more
> sense to run it until it gets "too slow".

I disagree strongly. You should throw out unbalanced binary trees and
linked lists and the like and concentrate on solid contenders.

But it's your test. You do as you like.

Anyway, even a well-thought-out test is subject to all kinds of
criticisms due to the CPU architecture, the distribution of the key
values, the quality of the data structure implementation etc etc.


Marko


From greg.ewing at canterbury.ac.nz  Tue Mar 18 20:07:12 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 19 Mar 2014 13:07:12 +1300
Subject: Controlling buffer alignment in file.read()
In-Reply-To: <mailman.8265.1395184430.18130.python-list@python.org>
References: <mailman.8260.1395174272.18130.python-list@python.org>
 <bos1vgF8r6oU1@mid.individual.net>
 <mailman.8265.1395184430.18130.python-list@python.org>
Message-ID: <bos5diF9glrU1@mid.individual.net>

Haralanov, Mitko wrote:

> The problem is not controlling the number of bytes read. That part seems to
> be working. The issue is that the buffer into which the data is placed needs
> to be of certain alignment (8byte-aligned). Python does not seem to have a
> way that allows me to control that.

Hmmm, that could be tricky. Have you tried using os.read()?
If you're lucky, Python will be using a malloc() call or
equivalent to create a str/bytes object to read the data
into, and that will return something platform-aligned.

If you're unlucky, there's probably no pure-Python
solution, and you might need to write a small C or
Cython module to accomplish this trick.


-- 
Greg


From drsalists at gmail.com  Tue Mar 18 21:01:59 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Tue, 18 Mar 2014 18:01:59 -0700
Subject: Controlling buffer alignment in file.read()
In-Reply-To: <F5ED8E150D0FF14F82CAF3C46756763232396ECB@FMSMSX104.amr.corp.intel.com>
References: <F5ED8E150D0FF14F82CAF3C46756763232396ECB@FMSMSX104.amr.corp.intel.com>
Message-ID: <CAGGBd_oACzpjETDNWR+RfF6gAOUGHjfPZddGKjzR66Uc3oZHrg@mail.gmail.com>

On Tue, Mar 18, 2014 at 1:23 PM, Haralanov, Mitko
<mitko.haralanov at intel.com> wrote:
> Hi all,
>
> I am using Python to read from a binary device file which requires that all read sizes are in 8byte multiples and the user's buffer is 8byte aligned.
>
> I am currently using a file object and the file.read() method. However, the issue is that the file.read() method allocates the buffer passed to C function under the covers and, therefore, the alignment is arbitrary.
>
> Is there a way that I can get file.read() to use an 8byte aligned buffer?

This is a lot like what my odirect project does:
http://stromberg.dnsalias.org/~strombrg/odirect/

It does buffer alignment, because O_DIRECT requires buffer alignment.
It's a Python-callable SWIG wrapper for some C code.


From ckaynor at zindagigames.com  Tue Mar 18 21:02:11 2014
From: ckaynor at zindagigames.com (Chris Kaynor)
Date: Tue, 18 Mar 2014 18:02:11 -0700
Subject: Balanced trees
In-Reply-To: <8738ifqlaw.fsf@elektro.pacujo.net>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
Message-ID: <CALvWhxtdLL6zjFPNHUG4yM9t1Y6tHHqkg1ObKLJo0sE7cqPTQg@mail.gmail.com>

>
> On Tue, Mar 18, 2014 at 1:55 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>
Dan Stromberg <drsalists at gmail.com>:
>> > The results are at
>> >
>> http://stromberg.dnsalias.org/~strombrg/python-tree-and-heap-comparison/2014-03/
>
>

  Size: 1048576, duration:  75.3, dictionary type: dict
>     [...]
>     Size:  262144, duration:  66.1, dictionary type: AVL_tree
>     [...]
>     Size:   65536, duration:  77.3, dictionary type: blist.sorteddict
>

Taking a quick look at this, I think it might be made much clearer if the
number/second were added to the output. While it can be computed off the
displayed data, it would make it much easier to compare in the table view
by including it. Something like:

  Size: 1048576, duration:  75.3, dictionary type: 13925/second: dict
  Size:  262144, duration:  66.1, dictionary type: 3965/second: AVL_tree
  Size:   65536, duration:  77.3, dictionary type: 847/second:
blist.sorteddict

Chris
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From steve+comp.lang.python at pearwood.info  Tue Mar 18 21:15:23 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 19 Mar 2014 01:15:23 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
 <87wqfrp3jk.fsf@elektro.pacujo.net>
 <mailman.8264.1395181297.18130.python-list@python.org>
 <87r45zf6fu.fsf@elektro.pacujo.net>
Message-ID: <5328efab$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Wed, 19 Mar 2014 01:11:33 +0200, Marko Rauhamaa wrote:

> Dan Stromberg <drsalists at gmail.com>:

>> Rather than throw out unbalanced binary tree altogether, it makes more
>> sense to run it until it gets "too slow".
> 
> I disagree strongly. You should throw out unbalanced binary trees and
> linked lists and the like and concentrate on solid contenders.

If you are in a position to randomize the data before storing it in the 
tree, an unbalanced binary tree is a solid contender. The overhead will 
likely be much less than any balanced tree, and the probability of 
degenerate behaviour negligible for any amount of data big enough to 
really matter.



-- 
Steven


From steve+comp.lang.python at pearwood.info  Tue Mar 18 21:15:53 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 19 Mar 2014 01:15:53 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
 <87wqfrp3jk.fsf@elektro.pacujo.net>
 <mailman.8264.1395181297.18130.python-list@python.org>
Message-ID: <5328efc8$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 18 Mar 2014 15:21:28 -0700, Dan Stromberg wrote:

> On Tue, Mar 18, 2014 at 3:03 PM, Marko Rauhamaa <marko at pacujo.net>
> wrote:
>> Dan Stromberg <drsalists at gmail.com>:
>> For a proper comparison, I'd like a fixed, identical dataset and set of
>> operations run against each data structure.
>>
>> How about this test program:
> 
> I used to do essentially this, but it was time-prohibitive and produced
> harder-to-read graphs - harder to read because the enormous values of
> the bad trees were dwarfing the values of the good trees.

A log graph may be the solution to that: graph the log of the time rather 
than time itself.



-- 
Steven


From tjreedy at udel.edu  Tue Mar 18 21:38:06 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 18 Mar 2014 21:38:06 -0400
Subject: Question about Source Control
In-Reply-To: <bortetF7t42U1@mid.individual.net>
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <mailman.8238.1395124947.18130.python-list@python.org>
 <bortetF7t42U1@mid.individual.net>
Message-ID: <lgasdj$93f$1@ger.gmane.org>

On 3/18/2014 5:51 PM, Gregory Ewing wrote:
> Frank Millman wrote:
>> These are the kind of stumbling blocks that prevented me from
>> succeeding in my previous attempt. I have a vague recollection that I
>> set it up on machine A, but then hit a problem because machines B and
>> C both accessed the same directory, but with different names
>
> For dealing with your practice of editing on one machine and
> running on another, you may be best off having just *one* local
> repository, residing on the shared file system. Whichever machine
> you're working on, you cd to the shared directory and use hg or
> git commands from there, so all the pathnames you're using are
> relative.

At least with hg, one should best test the code in the working directory 
*before* committing to the local repository. The one local repository 
could still be a close of a master repository somewhere else. One can 
push multiple commits at once, either as the end of a work session or 
when one has done enough to become paranoid about losing work.



-- 
Terry Jan Reedy



From nathanjbruce at gmail.com  Tue Mar 18 21:54:55 2014
From: nathanjbruce at gmail.com (Nathan Bruce)
Date: Wed, 19 Mar 2014 12:54:55 +1100
Subject: No subject
Message-ID: <CALX+1eRMxPv07eqVMd5PtAAVTC94oyyS3NbqS6ZaQdWov+dVqA@mail.gmail.com>

Hi I was wondering how much your oxycontins are for what mg and quantity.
Also do you guys sell dilaudid?

Thank you
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From python.list at tim.thechases.com  Tue Mar 18 22:12:35 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Tue, 18 Mar 2014 21:12:35 -0500
Subject: Question about Source Control
In-Reply-To: <lgasdj$93f$1@ger.gmane.org>
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <mailman.8238.1395124947.18130.python-list@python.org>
 <bortetF7t42U1@mid.individual.net> <lgasdj$93f$1@ger.gmane.org>
Message-ID: <20140318211235.7be2bd4d@bigbox.christie.dr>

On 2014-03-18 21:38, Terry Reedy wrote:
> At least with hg, one should best test the code in the working
> directory *before* committing to the local repository. 

I don't know if this is a hg-vs-git way of thinking, but I tend to
frequently commit things on a private development branch regardless
of brokenness, but once I get it working, I flatten & clean up those
changes ("rebase" in git terms, which I believe has been adopted as a
standardly-available-but-not-enabled-by-default module in hg) into
logical units of change-sets that I then test individually before
applying them to my more public-facing branch.  This produces clean
history that makes it easy for others to see what's going on.

-tkc





From rosuav at gmail.com  Tue Mar 18 22:34:09 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 19 Mar 2014 13:34:09 +1100
Subject: Question about Source Control
In-Reply-To: <20140318211235.7be2bd4d@bigbox.christie.dr>
References: <lg6s09$irl$1@ger.gmane.org>
 <CAPTjJmqPca5cnNWu8T5BZhpH665X0=mrf7bJaLqVrQVMjZWu1g@mail.gmail.com>
 <lg8m6b$c8t$1@ger.gmane.org>
 <CAPTjJmqHXh2M3-QGbeLV_AkGAJzMEYmbuDLy8_dkpnhrpSUVMQ@mail.gmail.com>
 <mailman.8238.1395124947.18130.python-list@python.org>
 <bortetF7t42U1@mid.individual.net> <lgasdj$93f$1@ger.gmane.org>
 <20140318211235.7be2bd4d@bigbox.christie.dr>
Message-ID: <CAPTjJmp96CtHK1EaHrSiWMmjuRawrhVNknjPODn4m5Tkz=wMaA@mail.gmail.com>

On Wed, Mar 19, 2014 at 1:12 PM, Tim Chase
<python.list at tim.thechases.com> wrote:
> On 2014-03-18 21:38, Terry Reedy wrote:
>> At least with hg, one should best test the code in the working
>> directory *before* committing to the local repository.
>
> I don't know if this is a hg-vs-git way of thinking, but I tend to
> frequently commit things on a private development branch regardless
> of brokenness, but once I get it working, I flatten & clean up those
> changes ("rebase" in git terms, which I believe has been adopted as a
> standardly-available-but-not-enabled-by-default module in hg) into
> logical units of change-sets that I then test individually before
> applying them to my more public-facing branch.  This produces clean
> history that makes it easy for others to see what's going on.

My approach to rebasing is derived from the accountancy concepts my
Dad taught me. You create transactions, invoices, whatever, and you
can freely edit them so long as they're the "current batch". It's very
clear what the current batch is and where history begins. Then when
you update that batch, it becomes history and is indelible; if you
find an error in history, you put a new transaction through that
updates it (or maybe reverses it completely, so you can then do a new
clean transaction), which will have its own date (the date of the
correction) and its own identity. [1] In git terms, that means commits
above origin/master are freely editable, but as soon as anything's
pushed, it's not to be changed. I violate that rule only very VERY
occasionally, and only with the understanding that every clone of the
repo will have to be manually updated.

The "git rebase -i" command is perfect for this - it lets you rewrite
anything that isn't pushed yet, by default. I made myself a hook
script that helps with this; between that and the "autosquash" feature
of git rebase interactive, it's easy to fiddle with unpushed changes.
Let's say you discover a typo in an unpushed commit, and go and fix
the corresponding file. As long as it's a one-file edit, and the most
recent edit to that file is the commit you want to fix up, just type:

$ git commit -amf

or

$ git commit some-file -mf

and it'll make a fixup commit marked with that commit's message. Then:

$ git rebase -i

will notice that (if autosquash is enabled) and offer to squash the
two commits together. In all cases, only unpushed commits are
considered; everything from origin/master is untouchable.

If anyone wants the script, I'm happy to share, though it is
git-specific. Porting it to hg (does hg do hooks? I'm sure it must) is
left as an exercise for the reader :)

ChrisA

[1] Linking this in with a previous thread on identity vs value: a
transaction definitely has an identity, which may or may not be
representable with some sort of database ID field. The identity might
be something like "third row of the current batch" and nothing more,
but it has one.


From marwa.kotb98 at gmail.com  Wed Mar 19 01:50:58 2014
From: marwa.kotb98 at gmail.com (marwa kotb)
Date: Tue, 18 Mar 2014 22:50:58 -0700 (PDT)
Subject: Greetings from Al-Madinah International University
Message-ID: <79a274b0-ebc4-42bb-9a29-cede4a1db97b@googlegroups.com>

Al Salam Alaykom w rahmat allah w barkato

 
Dear : mr \  mrs
We are pleased that on behalf of the Al-Madinah International University [MEDIU] greetings and best wishes for you continued success , coupled with the sincere invitations for your further success and development and growth.
 
 
Al-Madinah International University [MEDIU] Malaysia: "University City World [MEDIU] Malaysia" is one of the leading universities of Malaysia, which is characterized by excellence and excellence of technical and higher education areas, and " Al-Madinah International University [MEDIU] " is a multiple cultures and areas of study and is based
Malaysia  Shah Alam , Here is a brief history.
1. " Al-Madinah International University [MEDIU]" founded early in 2004 in Medinah  Almonowra 
 
2. In 19 / July / 2006, the university received the invitation of the Malaysian Ministry of Higher Education for the establishment of the University Centre in Malaysia.
 
3. On 20 / July / 2007, the university obtained full license from the Ministry of Higher Education Malaysia to be the first international  Malaysian University pursuing a systematic distance education using e-learning Targeting the  Students from around the world.
 
4. In early of February of 2008 the university began full operation of reception of students. 
5. joined the university for beginning of the year 2009, approximately [1500 ] students from different countries, while the number of applications submitted to the University of [3000] enrollment request.
 
. 6. Early / 2009. University offered more than (24) academic program accredited by the Accreditation Authority and the Ministry of Higher Education (Malaysia), and more (34) accredited course in Arabic and English language center.
 
. 7. Early 2009. Varied the levels of academic programs at the university to include foundation studies ,  Pre-university, diploma, bachelor's degree - graduate studies, language training courses.
8. Mid-2009. The number of students who were enrolled in the university more than (4701) students from more than 40 nationalities around the world.
 
. 9. The third quarter of 2009. The Al-Madinah International University [MEDIU] Passed successfully institutional inspection held by the Malaysian Ministry of Higher Education to ensure quality of academic and administrative of the University.
 
10 . The end of 2009. The number of applications increased by the University of (6508) Application from more than (60) countries around the world, while the number of students enrolled in the University (2482 )
 
11. The end of 2009.The university Completed the (10) new programs of study for approval by the  Malaysian accreditation of Graduate Studies.
 
12. The end of 2009. The Al-Madinah International University [MEDIU] started the procedures to start the constituent university education in the disciplines of direct scientific and practical, including a new Computer Science, Finance and Administration, Engineering and intending to be started by mid-year 2010.
 
13. . Early in 2010. The number of students of the University increased to (3057) students from around the world, from the beginning of September  2010.
 
14. The end of 2010. The number of applications received the university for direct education on campus system around (511) applications and more than (154) enrollment students.
 
            15. Early of  2011. The number of applications received by the university to direct education on campus system (2312) The number of enrollment students  more than (362).
. . 16. Early in 2011. Al-Madinah International University [MEDIU] inclusion Programs of the  Al-Madinah International University [MEDIU] in full accreditation for four academic graduate programs in the Faculty of Islamic Sciences in the list of qualifications recognized by the Civil Service Commission, Malaysia
 
17. The end of 2011. The university  the graduating first graduating batch of students from the  Al-Medina International University  in the  master's programs, bachelor's and (84) students for the bachelor's degree, and (27) students for master's degree.
 
 
What distinguishes the Al-Medinah International University [MEDIU].
 
First, high-technical  and modern facilities: The technical infrastructure of the Al-Medinah International University  is designed to match the best standards in the field of modern e-learning and distance education, including those of infrastructure following matters: 
 
Al-Medinah International University website on the Internet "www.mediu.edu.my": which offers all university services, which content  admission, registration , inquiry , direct access to the lessons and communicate with lecturers  and administrators staff of t the university.
 
The electronic system of educational administration "Alim" for managing  the  academic affairs of  the university, which can be both a student university lectures , administrators and supervisors to manage all the  Process of study , direct communication, and dissemination the  academic ,  exercise and lectures of subjects.

The digital library
 
comprehensive


http://dlib.mediu.edu.my/ar/


   which provide for the student and university lecturer the most types of works and textbooks. 


a center of excellence for customer service, and to which the student or lecturer or Enquirer from which to obtain any type of services available, and has the potential to provide rapid communication. * universality: as the administrative staff and faculty members of the university comes from many nationalities and cultures from around the world, providing the University a global spin and helps students to adapt quickly in the air school at the university
 
Second, the various programs of study Accredited
 
The university from the set foundations academy to provide programs of study in varied levels : foundation studies , pre-university, diploma, undergraduate and postgraduate up to PhD, in a number of scientific disciplines, including disciplines of Islamic Sciences , Arabic Language , Finance and Management, Computer Science, and Education, and Applied Science, is certified all courses at the university in advance and before it is put by the appropriations and specifications Academy of Malaysia under the Ministry of Higher Education of Malaysia and the universally recognized as known for short as [MQA], has got the university to recognize the academic programs of excellence in more than 90 study programs. "Al-Madinah International   University," one of the first leading educational institutions in Malaysia in the field of higher education in a number of programs and disciplines that it has never in the field of e-learning.
 
Third: (distance education (through the five faculties are distributed as follows: -.
. 1. Faculty of Islamic Sciences
 2. Faculty of Languages
 3. College of Computer and Information Technology 
4. Faculty of Finance and Administration
 5. College of Education 6. College of Engineering
 7. Language Center
 8. Center for foundation Studies for the undergraduate
 
Fourth, academic curriculum, the arbitrator:
 
"International Al-Madinah  University " keen From the beginning to control the academic curriculum of the programs of study, preparation and by Accredited and recognized to their knowledge, experience, and the University provide a full academic curriculum, the, recording audio, text, references and sources of study and divided by the lectures of study according to the academic calendar in advance to students enrolled thus contributing to raising their level of education, academic quality and achieve the target..
 
Fifth, the development of comprehensive programs for students:
 
>From through the services offered by the "Al-Madinah International University [MEDIU]" of headquarter  or centers of services its Its service centers in each of the (Kuwait - Saudi Arabia - Indonesia - Thailand - Egypt - Singapore - Malaysia - Britain - Morocco - Ghana), the university offered and provide scientific skills and educational as well as basic education-oriented experience within the unique environment and means of educational Saattabrha graduates of the university that it has changed the course of their lives. in addition to the administrative staff and the university's highest levels of academic qualification , and equipped with extensive experience in teaching methods and supervision, which provides the most appropriate opportunities for students to develop their skills through leadership of a diverse global community, and is the university students and provides them with multiple skills and capabilities, Kmharrat use of modern technology, and proficiency in different languages, skills , personal development , leadership skills, social activities and sports.
 
Sixth: The tuition fees are reasonable: 
 
"Al-Madinah International University [MEDIU]" offers educated reasonable fee, where the tuition fees for diploma programs in Finance and Administration and Computer science  (the equivalent of a bachelor's degree) is about [4000] U.S. dollars to the length of the study and that the range of about two and a half to three years, while the total of tuition fees in undergraduate programs in Islamic studies and Arabic language for the entire duration of the study, which  about four years  [6000] to [7000] USD U.S., the average tuition fees for post master's degree in Islamic studies and Arabic language, which two years duration [6000] U.S. dollars.
 
thanks and appreciation to you for your perusal and hope of success
 
Best Regards,
Marketing Team of Al-Medinah International University


From frank at chagford.com  Wed Mar 19 02:41:35 2014
From: frank at chagford.com (Frank Millman)
Date: Wed, 19 Mar 2014 08:41:35 +0200
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org>
Message-ID: <lgbe6g$j9o$1@ger.gmane.org>


"Frank Millman" <frank at chagford.com> wrote in message 
news:lg6s09$irl$1 at ger.gmane.org...
> Hi all
>
> I know I *should* be using a Source Control Management system, but at 
> present I am not. I tried to set up Mercurial a couple of years ago, but I 
> think I set it up wrongly, as I got myself confused and found it more of a 
> hindrance than a help. Now I am ready to try again, but I want to avoid my 
> earlier mistakes.
>

Many thanks to all for the responses. I have a much better feel for it now. 
If anything, I have moved from being confused because I did not understand 
it, to being confused because there are so many options I am not sure which 
to select. However, I consider this to be progress!

I have decided to stick with Mercurial, simply because that is what I used 
in my previous attempt and I felt comfortable with it. Also I believe that 
Python itself uses it, so if it is good enough for them ...

Before actually plunging in, I would like to summarise what I think I have 
understood, and what steps I propose to take.

I realise now that my initial problem had nothing to do with SCM/VCS, and 
everything to do with my lack of knowledge of basic networking protocols. As 
I understand it now, if I want to share the repository over a network, I can 
choose between SSH and HTTP. I like the following quote from Joel Spolsky -

"The quick-and-dirty way to make a central repository is to use Mercurial's 
built in web-server. ... I'm going to configure the server to allow anybody 
in the world to do anything they want to it. ... Needless to say, this is 
rather unsafe, but if you're on a nice protected LAN at work and there's a 
good firewall and you trust everybody on your LAN, this is reasonably OK."

This describes my situation well, so to keep things simple I will start with 
this.

To recap my basic setup, I have machine A which holds the source directory, 
machine B which is used to edit the program, and machines B and C which are 
both used to run the program.

Initially, to prove that I understand the concept, I propose to install 
Mercurial on all three machines. Machine A will hold the central repository, 
which I will clone onto machines B and C. After editing on B, I will 'push' 
to A, and then from C 'pull' from A to get the latest version.

If this works, I will simplify it to make my life easier. My first thought 
was to remove the clone from machine C and set up an nfs share pointing to 
the working directory on machine A, so I don't need the 'pull' step. Then I 
thought, why not just point to the working directory on machine B, so then I 
can test the changes on C directly, without even having to 'push'. I realise 
that this is defeating the object of version control, but I think it makes 
sense. I will still use version control to maintain a full history of the 
project on machine A.

I appreciated Mark's comments about hosting his project on code.google.com - 
not just the mechanics, but the benefits that he experiences from sharing 
his code. I am actually getting closer to being able to do that with my 
project. Over the last few years I have frequently 'trashed' whole sections 
of my code and rewritten them, which I suspect would not endear me to 
someone attempting to collaborate with me. However, the broad framework is 
starting to settle down now, so I am starting to think about putting it out 
there. Then the question is which hosting service to use - there are so many 
of them. I will probably come back here for more advice when I get to that 
stage.

Frank





From rosuav at gmail.com  Wed Mar 19 03:09:58 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 19 Mar 2014 18:09:58 +1100
Subject: Question about Source Control
In-Reply-To: <lgbe6g$j9o$1@ger.gmane.org>
References: <lg6s09$irl$1@ger.gmane.org>
	<lgbe6g$j9o$1@ger.gmane.org>
Message-ID: <CAPTjJmqM+cxEwT+c2AkBYwAMa_i4tOubpxdbiJMfKOuHKdtSfA@mail.gmail.com>

On Wed, Mar 19, 2014 at 5:41 PM, Frank Millman <frank at chagford.com> wrote:
> I have decided to stick with Mercurial, simply because that is what I used
> in my previous attempt and I felt comfortable with it.

That's the best reason for choosing, really.
https://github.com/Rosuav/Gypsum/commit/0f973
> Also I believe that
> Python itself uses it, so if it is good enough for them ...

Mercurial is used by a good number of high-profile projects. You're
probably thinking of CPython, the implementation, but
Python-the-language is built on top of Mercurial too, with such as the
PEP repo and the web site (although I understand the latest version of
the web site is managed in git). Both git and hg are used by plenty of
solid projects, including the Linux kernel (git's original purpose),
themselves (git's development is managed in git, hg's is managed in
hg), and plenty of other big projects. This is one reason why I always
push people to either of those two, rather than to an unknown or
proprietary system that might have problems.

> I realise now that my initial problem had nothing to do with SCM/VCS, and
> everything to do with my lack of knowledge of basic networking protocols. As
> I understand it now, if I want to share the repository over a network, I can
> choose between SSH and HTTP. I like the following quote from Joel Spolsky -
>
> "The quick-and-dirty way to make a central repository is to use Mercurial's
> built in web-server. ... I'm going to configure the server to allow anybody
> in the world to do anything they want to it. ... Needless to say, this is
> rather unsafe, but if you're on a nice protected LAN at work and there's a
> good firewall and you trust everybody on your LAN, this is reasonably OK."
>
> This describes my situation well, so to keep things simple I will start with
> this.

Yep! People complain loudly about the insecurity of protocols like
FTP, but properly-firewalled networks with all members trusted are
more common than you might think - all you need is a basic home-grade
NAT router and a sysadmin whose competence exceeds the sensitivity of
your content.

> To recap my basic setup, I have machine A which holds the source directory,
> machine B which is used to edit the program, and machines B and C which are
> both used to run the program.
>
> Initially, to prove that I understand the concept, I propose to install
> Mercurial on all three machines. Machine A will hold the central repository,
> which I will clone onto machines B and C. After editing on B, I will 'push'
> to A, and then from C 'pull' from A to get the latest version.

Right. That's a nice standard setup. There'll be plenty of tutorials
that can walk you through setting that up. (Don't forget, btw, that
most Linux distributions will include Mercurial - just "apt-get
install mercurial" or "yum install mercurial".)

> If this works, I will simplify it to make my life easier. My first thought
> was to remove the clone from machine C and set up an nfs share pointing to
> the working directory on machine A, so I don't need the 'pull' step. Then I
> thought, why not just point to the working directory on machine B, so then I
> can test the changes on C directly, without even having to 'push'. I realise
> that this is defeating the object of version control, but I think it makes
> sense. I will still use version control to maintain a full history of the
> project on machine A.

It doesn't defeat the object of version control as long as you always
make logical, conceptual commits. However, it does introduce a
dependency (the NFS share) and the associated messes of file locking
and so on, so I personally would prefer to deploy a file-transfer
system, maybe like the one I described earlier, or maybe something
more like FTP. But do whatever makes sense for you.

> Over the last few years I have frequently 'trashed' whole sections
> of my code and rewritten them, which I suspect would not endear me to
> someone attempting to collaborate with me. However, the broad framework is
> starting to settle down now, so I am starting to think about putting it out
> there.

That's not in itself a problem. This commit made quite a few changes,
all at once:

https://github.com/Rosuav/Gypsum/commit/0f973

It does mean that anyone who's collaborating with you will need to
keep a close eye on what goes on, but that's true of any fast-moving
project. As things get more stable, it'll be easier to join in.

ChrisA


From wxjmfauth at gmail.com  Wed Mar 19 03:30:55 2014
From: wxjmfauth at gmail.com (wxjmfauth at gmail.com)
Date: Wed, 19 Mar 2014 00:30:55 -0700 (PDT)
Subject: 'complex' function with string argument.
In-Reply-To: <lg9rdm$us9$1@speranza.aioe.org>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg9rdm$us9$1@speranza.aioe.org>
Message-ID: <11b58171-a99b-4ddf-8e6c-7b4f3169c60c@googlegroups.com>


z = a + b*i     with a, b, elements of R
z = r*exp(i*phi)    with r, phi, elements of R
z = [[a, -b], [b, a]]   with a, b, elements of R

This is, in my mind, more questionable:

>>> complex(2, 1+1j)
(1+1j)
>>> 
>>> print(complex.__doc__)
complex(real[, imag]) -> complex number

Create a complex number from a real part and an optional imaginary part.
This is equivalent to (real + imag*1j) where imag defaults to 0.

jmf


From marko at pacujo.net  Wed Mar 19 04:49:33 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 19 Mar 2014 10:49:33 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
 <87wqfrp3jk.fsf@elektro.pacujo.net>
 <mailman.8264.1395181297.18130.python-list@python.org>
 <87r45zf6fu.fsf@elektro.pacujo.net>
 <5328efab$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87pplipo82.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> If you are in a position to randomize the data before storing it in
> the tree, an unbalanced binary tree is a solid contender.

Applications that can assume randomly distributed data are exceedingly
rare and even then, you can't easily discount the possibility of
worst-case ordering.

In fact, Dan himself said unbalanced trees performed so badly he
couldn't test them satisfactorily.


Marko


From marko at pacujo.net  Wed Mar 19 04:51:20 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 19 Mar 2014 10:51:20 +0200
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg9rdm$us9$1@speranza.aioe.org>
 <11b58171-a99b-4ddf-8e6c-7b4f3169c60c@googlegroups.com>
Message-ID: <87lhw6po53.fsf@elektro.pacujo.net>

wxjmfauth at gmail.com:

> This is, in my mind, more questionable:
>
>>>> complex(2, 1+1j)
> (1+1j)

I find it neat, actually.


Marko


From murukessanap at gmail.com  Wed Mar 19 04:55:26 2014
From: murukessanap at gmail.com (muru kessan)
Date: Wed, 19 Mar 2014 14:25:26 +0530
Subject: unable to import rlcompleter readline
Message-ID: <CACk27ULHNogjmnRrOBMXvLQYHeoqLOM48b+3f-SqqQwFkVZ3fA@mail.gmail.com>

hi guys,
i want the python interactive shell to be auto complete and i found that by
adding the following lines in PYTHONSTARTUP file it is possible

import rlcompleter, readline
readline.parse_and_bind('tab: complete')

but i get the following error in git bash shell
Note: i run windows8 as Operating System

Python 2.7 (r27:82525, Jul  4 2010, 07:43:08) [MSC v.1500 64 bit (AMD64)]
on win
32
Type "help", "copyright", "credits" or "license" for more information.
Traceback (most recent call last):
  File "C:\muru work 05-nov-2013\python\start.py", line 6, in <module>
    import rlcompleter, readline
ImportError: No module named readline

Any help would be appreciated

Thanks,
muru
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-list/attachments/20140319/0989849f/attachment.html>

From mail at timgolden.me.uk  Wed Mar 19 05:30:02 2014
From: mail at timgolden.me.uk (Tim Golden)
Date: Wed, 19 Mar 2014 09:30:02 +0000
Subject: unable to import rlcompleter readline
In-Reply-To: <CACk27ULHNogjmnRrOBMXvLQYHeoqLOM48b+3f-SqqQwFkVZ3fA@mail.gmail.com>
References: <CACk27ULHNogjmnRrOBMXvLQYHeoqLOM48b+3f-SqqQwFkVZ3fA@mail.gmail.com>
Message-ID: <5329639A.4090503@timgolden.me.uk>

On 19/03/2014 08:55, muru kessan wrote:
> hi guys,
> i want the python interactive shell to be auto complete and i found that
> by adding the following lines in PYTHONSTARTUP file it is possible
> 
> import rlcompleter, readline
> readline.parse_and_bind('tab: complete')
> 
> but i get the following error in git bash shell
> Note: i run windows8 as Operating System
> 
> Python 2.7 (r27:82525, Jul  4 2010, 07:43:08) [MSC v.1500 64 bit
> (AMD64)] on win
> 32
> Type "help", "copyright", "credits" or "license" for more information.
> Traceback (most recent call last):
>   File "C:\muru work 05-nov-2013\python\start.py", line 6, in <module>
>     import rlcompleter, readline
> ImportError: No module named readline

readline is commonly provided on *nix systems, but not on Windows. You
can install a plug-compatible version here:

  https://pypi.python.org/pypi/pyreadline/2.0

(ie pip install pyreadline)

or just use IPython which project maintains it:

  http://ipython.org/

NB installing pyreadline will override the way in which Python interacts
with the standard Windows console's up/down/history recall features.
(Assuming it hasn't changed since I last used it a few years ago).

TJG


From wxjmfauth at gmail.com  Wed Mar 19 05:52:56 2014
From: wxjmfauth at gmail.com (wxjmfauth at gmail.com)
Date: Wed, 19 Mar 2014 02:52:56 -0700 (PDT)
Subject: 'complex' function with string argument.
In-Reply-To: <87lhw6po53.fsf@elektro.pacujo.net>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg9rdm$us9$1@speranza.aioe.org>
 <11b58171-a99b-4ddf-8e6c-7b4f3169c60c@googlegroups.com>
 <87lhw6po53.fsf@elektro.pacujo.net>
Message-ID: <d1f09443-f5d4-4ed6-880f-bc15810a1fdd@googlegroups.com>

Le mercredi 19 mars 2014 09:51:20 UTC+1, Marko Rauhamaa a ?crit?:
> wxjmfauth at gmail.com:
> 
> 
> 
> > This is, in my mind, more questionable:
> 
> >
> 
> >>>> complex(2, 1+1j)
> 
> > (1+1j)
> 
> 
> 
> I find it neat, actually.
> 
> 
> 
> 
> 
> Marko

>>> # tricky: yes, neat: no
>>> complex(1+1j, 2)
(1+3j)
>>>


From marko at pacujo.net  Wed Mar 19 06:09:06 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 19 Mar 2014 12:09:06 +0200
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg9rdm$us9$1@speranza.aioe.org>
 <11b58171-a99b-4ddf-8e6c-7b4f3169c60c@googlegroups.com>
 <87lhw6po53.fsf@elektro.pacujo.net>
 <d1f09443-f5d4-4ed6-880f-bc15810a1fdd@googlegroups.com>
Message-ID: <87bnx233gd.fsf@elektro.pacujo.net>

wxjmfauth at gmail.com:

> Le mercredi 19 mars 2014 09:51:20 UTC+1, Marko Rauhamaa a ?crit?:
>> wxjmfauth at gmail.com:
>> >>>> complex(2, 1+1j)
>> > (1+1j)
>> 
>> I find it neat, actually.
>
>>>> # tricky: yes, neat: no
>>>> complex(1+1j, 2)
> (1+3j)

So complex(a, b) is documented to produce a+bj when a and b are integers
or floats. What's more natural than saying it produces a+bj when a and b
are complex numbers? It's a straightforward generalization that in no
way violates the more limited documentation.


Marko


From thrinaxodon.jm at bitch.invalid  Wed Mar 19 06:22:23 2014
From: thrinaxodon.jm at bitch.invalid (THRINAXODON JM)
Date: Wed, 19 Mar 2014 06:22:23 -0400
Subject: PNYIKOS DOWN AND UNDER!
Message-ID: <lgbr4n$sbr$1@speranza.aioe.org>

=======================
 >BREAKING NEWSSSSSSSSS
=======================
 >
RICHARD LEAKEY JUST DIED DUE TO HEART FAILURE!
 >
THE REASONS DESCRIBED BY THE MEDICAL TEAM IS THAT HIS WORK WAS
DISPROVEN, BY NONE OTHER THAN YOUR OWN BASTARD, THRINAXODON.
 >
THIS CAUSED LEAKEY'S HEART TO EXPLODE!
 >
THRINAXODON DANCED WITH JOY AS HE WAS GRANTED $600,000,000,000.000!
 >
TO WASTE YOUR TIME EVEN FURTHER, CHECK OUT THESE LINKS BELOW.
===========================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/threa
d/6f501c469c7af24f# 
<https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/6f501c469c7af24f#> 



https://groups.google.com/group/sci.bio.paleontology/browse_thread/threa
d/3aad75c16afb0b82# 
<https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/3aad75c16afb0b82#> 



==============================
======

http://thrinaxodon.wordpress.com/ <http://thrinaxodon.wordpress.com/>

===================================

THRINAXODON ONLY HAD THIS TO SAY:

"I..I...I...Can't believe it. This completely disproved Darwinian
orthodoxy."

===================================

THE BASTARDS AT THE SMITHSONIAN, AND THE LEAKEY FOUNDATION ARE ERODING
WITH FEAR.

===========================
THESE ASSHOLES ARE GOING TO DIE:
THOMAS AQUINAS;
ALDOUS HUXLEY;
BOB CASANVOVA;
SkyEyes;
DAVID IAIN GRIEG;
MARK ISAAK;
JOHN HARSHAM;
RICHARD NORMAN;
DR. DOOLITTLE;
CHARLES DARWIN;
MARK HORTON;
ERIK SIMPSON;
HYPATIAB7;
PAUL J. GANS;
JILLERY;
WIKI TRIK;
THRINAXODON;
PETER NYIKOS;
RON OKIMOTO;
JOHN S. WILKINS
===========================

THRINAXODON WAS SCOURING ANOTHER DEVONIAN FOSSIL BED, AND FOUND A
HUMAN SKULL, AND A HUMAN FEMUR. HE ANALYSED THE FINDS, AND SAW THAT
THEY WERE NOT NORMAL ROCKS. THESE WERE FOSSILIZED BONES. THEY EVEN HAD
TOOTH MARKS ON THEM. SO, THRINAXODON BROUGHT THEM TO THE LEAKEY
FOUNDATION, THEY UTTERLY DISMISSED IT, AND SAID, "We want to keep
people thinking that humans evolved 2 Ma." THRINAXODON BROUGHT HIS
SWORD, AND SAID, "SCIENCE CORRECTS ITSELF." RICHARD LEAKEY SAID, "That
is a myth, for people to believe in science." THRINAXODON PLANS TO
BRING DOOM TO SCIENCE, ITSELF.

============================

THRINAXODON IS NOW ON REDDIT

-- 
---Thrinaxodon



From ian.g.kelly at gmail.com  Wed Mar 19 06:33:34 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 19 Mar 2014 04:33:34 -0600
Subject: 'complex' function with string argument.
In-Reply-To: <87bnx233gd.fsf@elektro.pacujo.net>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg9rdm$us9$1@speranza.aioe.org>
 <11b58171-a99b-4ddf-8e6c-7b4f3169c60c@googlegroups.com>
 <87lhw6po53.fsf@elektro.pacujo.net>
 <d1f09443-f5d4-4ed6-880f-bc15810a1fdd@googlegroups.com>
 <87bnx233gd.fsf@elektro.pacujo.net>
Message-ID: <CALwzidmy6qnSXTfTitNJ2mw4ij87L4UeGJ+Xu4FyOc_GzC3F5g@mail.gmail.com>

On Wed, Mar 19, 2014 at 4:09 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> wxjmfauth at gmail.com:
>
>> Le mercredi 19 mars 2014 09:51:20 UTC+1, Marko Rauhamaa a ?crit :
>>> wxjmfauth at gmail.com:
>>> >>>> complex(2, 1+1j)
>>> > (1+1j)
>>>
>>> I find it neat, actually.
>>
>>>>> # tricky: yes, neat: no
>>>>> complex(1+1j, 2)
>> (1+3j)
>
> So complex(a, b) is documented to produce a+bj when a and b are integers
> or floats. What's more natural than saying it produces a+bj when a and b
> are complex numbers? It's a straightforward generalization that in no
> way violates the more limited documentation.

When is it ever useful though?  I only see a use for passing a as
complex if b is omitted, and I don't see any use for passing b as
complex.  If there's no use case, then it's just a confusing edge case
that will catch unsuspecting programmers who thought the data they
were passing in was real-valued when actually it wasn't.  It would be
better to raise an exception in either of the cases above, in my
opinion.  If you really want to form a complex a+bj from two other
complex numbers, there is always the explicit (a + b * 1j).

That said, complex numbers have been around since 1.4 or so, and
there's probably not much chance to change it now.


From marko at pacujo.net  Wed Mar 19 06:53:00 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 19 Mar 2014 12:53:00 +0200
Subject: 'complex' function with string argument.
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg9rdm$us9$1@speranza.aioe.org>
 <11b58171-a99b-4ddf-8e6c-7b4f3169c60c@googlegroups.com>
 <87lhw6po53.fsf@elektro.pacujo.net>
 <d1f09443-f5d4-4ed6-880f-bc15810a1fdd@googlegroups.com>
 <87bnx233gd.fsf@elektro.pacujo.net>
 <mailman.8276.1395225264.18130.python-list@python.org>
Message-ID: <877g7q31f7.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> On Wed, Mar 19, 2014 at 4:09 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> So complex(a, b) is documented to produce a+bj when a and b are integers
>> or floats. What's more natural than saying it produces a+bj when a and b
>> are complex numbers? It's a straightforward generalization that in no
>> way violates the more limited documentation.
>
> When is it ever useful though? [...] It would be better to raise an
> exception in either of the cases above, in my opinion.

I don't think it matters one way or another.

Medieval mathematicians had to address an analogous issue when they had
to decide if

   x + 0

was meaningful. After all, adding nothing doesn't make any sense and
should raise a ValueError exception...


Marko


From skip at pobox.com  Wed Mar 19 07:04:06 2014
From: skip at pobox.com (Skip Montanaro)
Date: Wed, 19 Mar 2014 06:04:06 -0500
Subject: 'complex' function with string argument.
In-Reply-To: <CALwzidmy6qnSXTfTitNJ2mw4ij87L4UeGJ+Xu4FyOc_GzC3F5g@mail.gmail.com>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg9rdm$us9$1@speranza.aioe.org>
 <11b58171-a99b-4ddf-8e6c-7b4f3169c60c@googlegroups.com>
 <87lhw6po53.fsf@elektro.pacujo.net>
 <d1f09443-f5d4-4ed6-880f-bc15810a1fdd@googlegroups.com>
 <87bnx233gd.fsf@elektro.pacujo.net>
 <CALwzidmy6qnSXTfTitNJ2mw4ij87L4UeGJ+Xu4FyOc_GzC3F5g@mail.gmail.com>
Message-ID: <CANc-5UxL+LdNja+mCan-fUYLAZw1DNhMmpY240o-FW5Ax-Nb3A@mail.gmail.com>

On Wed, Mar 19, 2014 at 5:33 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> When is it ever useful though?

About as often as int(0), float(0), or float(0.0) which all work as
expected, though probably don't turn up in a lot of code.

Skip


From vinay_sajip at yahoo.co.uk  Wed Mar 19 09:13:38 2014
From: vinay_sajip at yahoo.co.uk (Vinay Sajip)
Date: Wed, 19 Mar 2014 13:13:38 +0000 (GMT)
Subject: [ANN]: distlib 0.1.8 released on PyPI
Message-ID: <1395234818.65024.YahooMailNeo@web172401.mail.ir2.yahoo.com>

I've released version 0.1.8 of distlib on PyPI [1]. For newcomers,
distlib is a library of packaging functionality which is intended
to be?usable as the basis for third-party packaging tools.

The main changes in this release are as follows:

* Fixed issue #45: Improved thread-safety in SimpleScrapingLocator.
*?Fixed issue #42: Handling of pre-release legacy version numbers
? now mirrors setuptools logic.
* Added exists, verify, update, is_compatible and is_mountable methods
? to?the Wheel class (the update method fixed issue #41).
* Added a search method to the PackageIndex class.
* Fixed a bug in the Metadata.add_requirements method.
*?Allowed versions with a single numeric component and a local version
? component (tracking changes to PEP 440).* Corrected spelling of environment variable used for the stub launcher
? on OS X.
*?Avoided using pydist.json in 1.0 wheels (bdist_wheel writes a non-
? conforming pydist.json).

* Improved computation of ABI tags on Python versions where SOABI is not
? available, and improved computation of compatibility tags on OS X to
? allow for multiple architectures and older OS X versions.


A more detailed change log is available at [2]. Please try it out, and
if you find any problems or have any suggestions for?improvements, please
give some feedback using the issue tracker! [3]

Regards,

Vinay Sajip

[1] https://pypi.python.org/pypi/distlib/0.1.8?
[2] http://pythonhosted.org/distlib/overview.html#change-log-for-distlib?
[3] https://bitbucket.org/pypa/distlib/issues/new



From diccon.tesson at gmail.com  Wed Mar 19 09:11:48 2014
From: diccon.tesson at gmail.com (diccon.tesson at gmail.com)
Date: Wed, 19 Mar 2014 06:11:48 -0700 (PDT)
Subject: Printing characters outside of the ASCII range
In-Reply-To: <3d4644f8-ab88-41c5-9a52-2a5678dd64c0@googlegroups.com>
References: <3d4644f8-ab88-41c5-9a52-2a5678dd64c0@googlegroups.com>
Message-ID: <f99e87f3-9887-47f9-905b-d8f0ace54cce@googlegroups.com>

Your handling Pick Multi value fields aren't you ;)
Just hit the same issue, thanks all here for various solutions.
Interfacing with OpenQM / Scarlet DME here.


From steve+comp.lang.python at pearwood.info  Wed Mar 19 09:42:04 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 19 Mar 2014 13:42:04 GMT
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
 <87wqfrp3jk.fsf@elektro.pacujo.net>
 <mailman.8264.1395181297.18130.python-list@python.org>
 <87r45zf6fu.fsf@elektro.pacujo.net>
 <5328efab$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87pplipo82.fsf@elektro.pacujo.net>
Message-ID: <53299eac$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Wed, 19 Mar 2014 10:49:33 +0200, Marko Rauhamaa wrote:

> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
> 
>> If you are in a position to randomize the data before storing it in the
>> tree, an unbalanced binary tree is a solid contender.
> 
> Applications that can assume randomly distributed data are exceedingly
> rare 

Please re-read what I wrote. I didn't say "if your data comes to you 
fully randomized". I said "if you are in a position to randomize the data 
before storing it". In other words, if you actively randomize the data 
yourself.


> and even then, you can't easily discount the possibility of
> worst-case ordering.

Of course you can. If you have a million items, then the odds that those 
million items happen to be sorted (the worst-case order) are 1 in a 
million factorial. That's a rather small number, small enough that we can 
discount it from ever happening, not in a million lifetimes of the 
Universe.

Of course, you would be right to point out that one would also like to 
avoid *nearly* worst-case ordering. Nevertheless, there are Vastly more 
ways that the data will be sufficiently randomized as to avoid degenerate 
performance than the worst-case poor performance.

> In fact, Dan himself said unbalanced trees performed so badly he
> couldn't test them satisfactorily.

You're misrepresenting what Dan said. What he actually said was that 
unbalanced trees perform second only to dicts with random data, only with 
sorted data do they perform badly. His exact words were:

"For a series of random keys, it would do quite well (probably second only
to dict), but for a series of sequential keys it would take longer than
anyone would reasonably want to wait"



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From marko at pacujo.net  Wed Mar 19 09:54:40 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 19 Mar 2014 15:54:40 +0200
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
 <87wqfrp3jk.fsf@elektro.pacujo.net>
 <mailman.8264.1395181297.18130.python-list@python.org>
 <87r45zf6fu.fsf@elektro.pacujo.net>
 <5328efab$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87pplipo82.fsf@elektro.pacujo.net>
 <53299eac$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87siqe1efz.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> Please re-read what I wrote. I didn't say "if your data comes to you
> fully randomized". I said "if you are in a position to randomize the
> data before storing it". In other words, if you actively randomize the
> data yourself.

Yes, you could implement a "hash table" that way.


Marko


From roy at panix.com  Wed Mar 19 10:06:29 2014
From: roy at panix.com (Roy Smith)
Date: Wed, 19 Mar 2014 10:06:29 -0400
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
 <87wqfrp3jk.fsf@elektro.pacujo.net>
 <mailman.8264.1395181297.18130.python-list@python.org>
 <87r45zf6fu.fsf@elektro.pacujo.net>
 <5328efab$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87pplipo82.fsf@elektro.pacujo.net>
 <53299eac$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-0F0BB4.10062919032014@news.panix.com>

In article <53299eac$0$29994$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> If you have a million items, then the odds that those 
> million items happen to be sorted (the worst-case order) are 1 in a 
> million factorial. That's a rather small number, small enough that we can 
> discount it from ever happening, not in a million lifetimes of the 
> Universe.

If the items are coming from some inherently random process, then I 
agree.  But, not all data sources are random.

Imagine you had a web site, and wanted to store various bits of data 
from the stream of input requests.  You decided that the data structure 
you were going to use was a balanced tree.  If your keys were, say, a 
hash of the client's IP address, then it's a pretty good guess they're 
random.  But, what if the keys were the time the request was received?  
Those are obviously not random, and using them as a keys in a balanced 
tree would give you sub-optimum performance.

This is not a hypothetical scenario.  Songza uses MongoDB as our 
database.  The indexes are balanced trees.  One of our biggest 
collections has a multi-component key, one of the components being the 
request time truncated to the hour.  Insertion time into that collection 
has an obvious sawtooth shape, with performance degrading as each hour 
progresses and jumping back up as the time rolls over to the next hour.  
This is due (we believe :-)) to the constant rebalancing of the index 
trees.

Almost-sorted data sets are very common.  For example, here's a pipeline 
I run a lot (from memory, could have gotten some detail wrong):

grep pattern lofgile | awk '{print $7}' | sed 's/:[0-9][0-9]$//' | sort 
| uniq -c

Field 7 is the timestamp for when a request came in.  What I'm doing 
here is counting how many requests of a certain type came in during each 
minute of the day.  Logging isn't exactly in chronological order, so I 
need to sort the times before I count them.  But, it's in *almost* 
chronological order; a sort which had pathologically bad behavior on 
almost sorted data would be unusable here.


From breamoreboy at yahoo.co.uk  Wed Mar 19 10:19:14 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 19 Mar 2014 14:19:14 +0000
Subject: Printing characters outside of the ASCII range
In-Reply-To: <f99e87f3-9887-47f9-905b-d8f0ace54cce@googlegroups.com>
References: <3d4644f8-ab88-41c5-9a52-2a5678dd64c0@googlegroups.com>
 <f99e87f3-9887-47f9-905b-d8f0ace54cce@googlegroups.com>
Message-ID: <lgc90o$o71$1@ger.gmane.org>

On 19/03/2014 13:11, diccon.tesson at gmail.com wrote:
> Your handling Pick Multi value fields aren't you ;)
> Just hit the same issue, thanks all here for various solutions.
> Interfacing with OpenQM / Scarlet DME here.
>

The context is conspicious by its absence.  In future would you please 
be kind enough to provide some.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From wxjmfauth at gmail.com  Wed Mar 19 10:35:06 2014
From: wxjmfauth at gmail.com (wxjmfauth at gmail.com)
Date: Wed, 19 Mar 2014 07:35:06 -0700 (PDT)
Subject: 'complex' function with string argument.
In-Reply-To: <mailman.8277.1395227054.18130.python-list@python.org>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg9rdm$us9$1@speranza.aioe.org>
 <11b58171-a99b-4ddf-8e6c-7b4f3169c60c@googlegroups.com>
 <87lhw6po53.fsf@elektro.pacujo.net>
 <d1f09443-f5d4-4ed6-880f-bc15810a1fdd@googlegroups.com>
 <87bnx233gd.fsf@elektro.pacujo.net>
 <CALwzidmy6qnSXTfTitNJ2mw4ij87L4UeGJ+Xu4FyOc_GzC3F5g@mail.gmail.com>
 <mailman.8277.1395227054.18130.python-list@python.org>
Message-ID: <4021d887-0673-42a3-816d-74bc8755a082@googlegroups.com>

Le mercredi 19 mars 2014 12:04:06 UTC+1, Skip Montanaro a ?crit?:
> On Wed, Mar 19, 2014 at 5:33 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> 
> > When is it ever useful though?
> 
> 
> 
> About as often as int(0), float(0), or float(0.0) which all work as
> 
> expected, though probably don't turn up in a lot of code.
> 
> 
> 
> Skip

Your comment is equivalent to this:

>>> complex(1+2.0j)
(1+2j)
>>> complex(0+0.0j)
0j

Both, the constructor and the docstring, are not so clean.

What to say about the __repr__ ? Are not a and b
supposed to be floats? (elements of R)

>>> 0
0
>>> 0.0
0.0
>>> 0j
0j
>>> 1.0 + 2.0j
(1+2j)
>>> 1.
1.0
>>> 1
1
>>> (1 + 2.0j).real
1.0
>>> type((1 + 2.0j).real)
<class 'float'>

jmf



From zachary.ware+pylist at gmail.com  Wed Mar 19 10:43:30 2014
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Wed, 19 Mar 2014 09:43:30 -0500
Subject: Printing characters outside of the ASCII range
In-Reply-To: <lgc90o$o71$1@ger.gmane.org>
References: <3d4644f8-ab88-41c5-9a52-2a5678dd64c0@googlegroups.com>
 <f99e87f3-9887-47f9-905b-d8f0ace54cce@googlegroups.com>
 <lgc90o$o71$1@ger.gmane.org>
Message-ID: <CAKJDb-MRzvTWADzbwUQDhREpUOGoFZcUkDsQPgnkvi=ApzHS3g@mail.gmail.com>

On 19/03/2014 13:11, diccon.tesson at gmail.com wrote:
> Your handling Pick Multi value fields aren't you ;)
> Just hit the same issue, thanks all here for various solutions.
> Interfacing with OpenQM / Scarlet DME here.

For future posts, please be sure to quote what you're replying to.
Google Groups makes things easy to find and reply to, but this is a
mailing list.  When we receive a mail with just a subject line and a
cryptic message, we're likely to think it spam and ignore future mail
from that sender.  It's also a bit less than ideal to reply to years
old threads.

On Wed, Mar 19, 2014 at 9:19 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> The context is conspicious by its absence.  In future would you please be
> kind enough to provide some.

In a fit of curiosity, I went looking:
https://mail.python.org/pipermail/python-list/2012-November/634803.html
 I'm almost surprised it wasn't any older than that :)

Ironically, on my way down the November 2012 archive page, I noticed a
long thread about "Obnoxious postings from Google Groups".

-- 
Zach


From breamoreboy at yahoo.co.uk  Wed Mar 19 11:14:20 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 19 Mar 2014 15:14:20 +0000
Subject: Printing characters outside of the ASCII range
In-Reply-To: <CAKJDb-MRzvTWADzbwUQDhREpUOGoFZcUkDsQPgnkvi=ApzHS3g@mail.gmail.com>
References: <3d4644f8-ab88-41c5-9a52-2a5678dd64c0@googlegroups.com>
 <f99e87f3-9887-47f9-905b-d8f0ace54cce@googlegroups.com>
 <lgc90o$o71$1@ger.gmane.org>
 <CAKJDb-MRzvTWADzbwUQDhREpUOGoFZcUkDsQPgnkvi=ApzHS3g@mail.gmail.com>
Message-ID: <lgcc81$49n$1@ger.gmane.org>

On 19/03/2014 14:43, Zachary Ware wrote:
> Ironically, on my way down the November 2012 archive page, I noticed a
> long thread about "Obnoxious postings from Google Groups".
>

Thankfully the number of grotty postings from gg has dropped 
considerably.  Sadly our resident unicode expert quite deliberately 
continues to use it in a manner which is designed to annoy.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ethan at stoneleaf.us  Wed Mar 19 11:15:49 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Wed, 19 Mar 2014 08:15:49 -0700
Subject: Balanced trees
In-Reply-To: <5328efc8$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
 <87wqfrp3jk.fsf@elektro.pacujo.net>
 <mailman.8264.1395181297.18130.python-list@python.org>
 <5328efc8$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5329B4A5.1030206@stoneleaf.us>

On 03/18/2014 06:15 PM, Steven D'Aprano wrote:
> On Tue, 18 Mar 2014 15:21:28 -0700, Dan Stromberg wrote:
>
>> On Tue, Mar 18, 2014 at 3:03 PM, Marko Rauhamaa <marko at pacujo.net>
>> wrote:
>>> Dan Stromberg <drsalists at gmail.com>:
>>> For a proper comparison, I'd like a fixed, identical dataset and set of
>>> operations run against each data structure.
>>>
>>> How about this test program:
>>
>> I used to do essentially this, but it was time-prohibitive and produced
>> harder-to-read graphs - harder to read because the enormous values of
>> the bad trees were dwarfing the values of the good trees.
>
> A log graph may be the solution to that: graph the log of the time rather
> than time itself.

I don't think that will solve the problem of not wanting to wait three days for the test to finish.  ;)

--
~Ethan~


From nikolaus.fleischhacker at gmail.com  Wed Mar 19 05:27:14 2014
From: nikolaus.fleischhacker at gmail.com (audiowerk)
Date: Wed, 19 Mar 2014 02:27:14 -0700 (PDT)
Subject: Kivy contest 2014
In-Reply-To: <CAPztPCf9PzfjJ5E1Cw8Ami5aYDBxDZAz8txv81GduHC6wTdKQQ@mail.gmail.com>
References: <CAPztPCf9PzfjJ5E1Cw8Ami5aYDBxDZAz8txv81GduHC6wTdKQQ@mail.gmail.com>
Message-ID: <fb28447a-7dff-4373-8489-00484a96eaf8@googlegroups.com>

Hi!

Is there already a date when the theme will be announced?

Am Sonntag, 16. M?rz 2014 18:42:16 UTC+1 schrieb qua-non:
>
> Hi folks,
>
> Kivy will be holding it's programming contest for 2014 starting April 15th.
>
> For details please visit http://kivy.org/#contest
>
> If you are interested in sponsoring the contest, please contact us at 
> con... at kivy.org <javascript:>.
>
>
> [image: Inline image 1]
>  
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From ian.g.kelly at gmail.com  Wed Mar 19 14:45:06 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 19 Mar 2014 12:45:06 -0600
Subject: 'complex' function with string argument.
In-Reply-To: <CANc-5UxL+LdNja+mCan-fUYLAZw1DNhMmpY240o-FW5Ax-Nb3A@mail.gmail.com>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg9rdm$us9$1@speranza.aioe.org>
 <11b58171-a99b-4ddf-8e6c-7b4f3169c60c@googlegroups.com>
 <87lhw6po53.fsf@elektro.pacujo.net>
 <d1f09443-f5d4-4ed6-880f-bc15810a1fdd@googlegroups.com>
 <87bnx233gd.fsf@elektro.pacujo.net>
 <CALwzidmy6qnSXTfTitNJ2mw4ij87L4UeGJ+Xu4FyOc_GzC3F5g@mail.gmail.com>
 <CANc-5UxL+LdNja+mCan-fUYLAZw1DNhMmpY240o-FW5Ax-Nb3A@mail.gmail.com>
Message-ID: <CALwzidn9hhAtO_S6Rh6_nXa9N937f4i=TVbmdwwtvCjpQwP9Pg@mail.gmail.com>

On Wed, Mar 19, 2014 at 5:04 AM, Skip Montanaro <skip at pobox.com> wrote:
> On Wed, Mar 19, 2014 at 5:33 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> When is it ever useful though?
>
> About as often as int(0), float(0), or float(0.0) which all work as
> expected, though probably don't turn up in a lot of code.

The analogous call to those is complex(1+2j), which I have no problem
with, not complex(1+2j, 3+4j).


From ian.g.kelly at gmail.com  Wed Mar 19 15:35:05 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 19 Mar 2014 13:35:05 -0600
Subject: 'complex' function with string argument.
In-Reply-To: <877g7q31f7.fsf@elektro.pacujo.net>
References: <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com>
 <lg779d$5f4$2@speranza.aioe.org>
 <5327d112$0$2923$c3e8da3$76491128@news.astraweb.com>
 <lg9rdm$us9$1@speranza.aioe.org>
 <11b58171-a99b-4ddf-8e6c-7b4f3169c60c@googlegroups.com>
 <87lhw6po53.fsf@elektro.pacujo.net>
 <d1f09443-f5d4-4ed6-880f-bc15810a1fdd@googlegroups.com>
 <87bnx233gd.fsf@elektro.pacujo.net>
 <mailman.8276.1395225264.18130.python-list@python.org>
 <877g7q31f7.fsf@elektro.pacujo.net>
Message-ID: <CALwzidndBwGfOOeVbBwXZiwKKMmUUNuQ_CLPCQLsX9Ek5E=dtA@mail.gmail.com>

On Wed, Mar 19, 2014 at 4:53 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Ian Kelly <ian.g.kelly at gmail.com>:
>
>> On Wed, Mar 19, 2014 at 4:09 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> So complex(a, b) is documented to produce a+bj when a and b are integers
>>> or floats. What's more natural than saying it produces a+bj when a and b
>>> are complex numbers? It's a straightforward generalization that in no
>>> way violates the more limited documentation.
>>
>> When is it ever useful though? [...] It would be better to raise an
>> exception in either of the cases above, in my opinion.
>
> I don't think it matters one way or another.
>
> Medieval mathematicians had to address an analogous issue when they had
> to decide if
>
>    x + 0
>
> was meaningful. After all, adding nothing doesn't make any sense and
> should raise a ValueError exception...

I wasn't aware that algebra had ValueErrors.  Describing an operation
as "undefined" isn't the same thing.  Anyway, if mathematicians
discover that the definitions of the past were flawed or incomplete,
then they redefine them.  Case in point, if we were still using
Brahmagupta's rules for zero, then 0/0 would be 0.

Python though has backward compatibility to worry about.  Because of
this, it is much simpler to add wanted behavior than to remove
unwanted behavior. If an operation can be generalized but the
generalization has no apparent use case, it *may* be better to
disallow it, with the possibility of adding it later when a user pops
up and says "Hey, this would actually be useful to me", than to allow
it from the beginning, and then have no option to remove it later when
it turns out to be merely a nuisance.

Compare for example the 2-argument int constructor.  Normally this is
meant to be called like int("42", 13), where it will interpret the
digits passed as base 13 and return 54.  We might generalize that and
say that if the user passes int(42, 13), it should also return 54,
seeing that the repr of 42 provides the digits "42".  It is more
likely though that this call merely indicates a bug in the user's
code, and fortunately in this case what Python actually does is to
raise a TypeError.

Anyway, curious though this tangent is, further discussion is unlikely
to produce any useful outcome, so I'll just leave it there.


From alexanderjohntaylor at gmail.com  Wed Mar 19 17:33:15 2014
From: alexanderjohntaylor at gmail.com (Alexander Taylor)
Date: Wed, 19 Mar 2014 14:33:15 -0700 (PDT)
Subject: Kivy contest 2014
In-Reply-To: <fb28447a-7dff-4373-8489-00484a96eaf8@googlegroups.com>
References: <CAPztPCf9PzfjJ5E1Cw8Ami5aYDBxDZAz8txv81GduHC6wTdKQQ@mail.gmail.com>
 <fb28447a-7dff-4373-8489-00484a96eaf8@googlegroups.com>
Message-ID: <7178e6e0-ad32-4cc0-b4a1-47a587fb5f69@googlegroups.com>

The theme will be announced when the contest officially starts, the 15th 
April.

On Wednesday, 19 March 2014 09:27:14 UTC, audiowerk wrote:
>
> Hi!
>
> Is there already a date when the theme will be announced?
>
> Am Sonntag, 16. M?rz 2014 18:42:16 UTC+1 schrieb qua-non:
>>
>> Hi folks,
>>
>> Kivy will be holding it's programming contest for 2014 starting April 
>> 15th.
>>
>> For details please visit http://kivy.org/#contest
>>
>> If you are interested in sponsoring the contest, please contact us at 
>> con... at kivy.org.
>>
>>
>> [image: Inline image 1]
>>  
>
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From abhishek1899 at gmail.com  Wed Mar 19 18:05:31 2014
From: abhishek1899 at gmail.com (Peace)
Date: Wed, 19 Mar 2014 15:05:31 -0700 (PDT)
Subject: Problem with pickle and restarting a program
Message-ID: <cc656034-01c4-430c-84f0-a181cef6560a@googlegroups.com>

In my GUI, the user enters two values: cellNumber(Integer) and SerialNumber(String)

I have the following piece of code in my view/controller:

####################The following function is called after the user enters the cellnumber and serial number##############
def ListenForDetails(status):
	cellNumber = status[0]
	SerialNumber = status[1]
	ModelInfo().CellList[cellNumber].receiveSerialNumber(SerialNumber)

------------------In my controller thread-----------------
class Controller(Thread):
	def __init__(self):
		Thread.__init__(self)
		self.start()
	
	def run(self):
		global SynchronizationVariable
		while SynchronizationVariable != 1:
			time.sleep(0.01)
		while 1:
			StateChanged = False
			for cells in ModelInfo().CellList:
				rc = cells.PollCells()
				if rc == 0:
					StateChanged = True
			if StateChanged:
				ModelInfo().save()
			time.sleep(1)

-------------------------------In my model.py script-------------------------------------

class CellInfo(): #This class encapsulates all the information present in a cell
	def __init__(self,cellNo):
		self.SerialNo = ""
		self.cellNo = cellNo
	
	def receiveSerialNumber(self, SerialNumber):
		self.SerialNo = SerialNumber

        def PollCells(self):
		RC = self.StateMachine[self.CurrentState](self)
		return RC

        ...all state machine functions here...


"""Model Info below"""
class ModelInfo(): #This class creates a list of cells.
	def __init__(self):
		print("Setting up a list of cells to iterate on")
		self.CellList = [] #List of all the cell Objects
		for index in xrange(0,24):
			print(self.CellList)
			self.CellList.append(CellInfo(index))
		
	def save(self):
		with open("RestoreInfo.p", "wb") as f:
			pickle.dump(self,f)

Model = ModelInfo() #Constructs an empty model

"""IN MAIN (In the controller script)"""
if __name__ == '__main__':
    if os.path.isfile( "RestoreInfo.p" ):
        with open("RestoreInfo.p", "rb") as f:
            model = pickle.load( f );
    else:
        model = model.ModelInfo();


The serial number field always remains empty even though I enter from the GUI and the receiveSerialNumber function is called and I explicitly initialize it to the variable in the model.
I'm trying to save the state of the program so that next time I open the application it resumes from where it left off. The problem is when I restart the application, the serial number is empty. What am I doing wrong here? Whenever I get a change in state (the RC value), I pickle and save to a file (restoreinfo.p). When I restart the application, the serial number is no longer there even though I enter it. Could you please let me know what is going wrong? Thank you.


From goswami.anjan at gmail.com  Wed Mar 19 19:03:09 2014
From: goswami.anjan at gmail.com (goswami.anjan at gmail.com)
Date: Wed, 19 Mar 2014 16:03:09 -0700 (PDT)
Subject: Problem in fetching blob or clob data with python and cx_oracle
Message-ID: <bf000f0e-a5e6-46e0-8395-fa201d7e375c@googlegroups.com>

It seems that when I attempt to download blob or clob data using fetchmany, it can not keep track of the LOB variable in subsequent fetch. The problem is over if I fetch one row at a time but it is not optimal. Can anyone give me an idea how to efficiently fetch columns with clob or blob data from oracle DB using python.

Thank you,
Anjan


From rhodri at wildebst.org.uk  Wed Mar 19 22:16:50 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Thu, 20 Mar 2014 02:16:50 -0000
Subject: Balanced trees
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1> <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
Message-ID: <op.xcz0mccp5079vu@gnudebeest>

On Tue, 18 Mar 2014 21:45:52 -0000, Dan Stromberg <drsalists at gmail.com>  
wrote:

> blist.sorteddict was able to do 65536 operations on a dictionary
> before taking more than 120 seconds to complete  - it took 77.3
> seconds to do 65536 operations.

65536 is a suspiciously round number.  You might want to double-
check that there's no 16-bit overflow causing something unexpected.

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From drsalists at gmail.com  Wed Mar 19 22:34:43 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Wed, 19 Mar 2014 19:34:43 -0700
Subject: Balanced trees
In-Reply-To: <op.xcz0mccp5079vu@gnudebeest>
References: <lennh4$kpm$1@cabale.usenet-fr.net>
 <CAPTjJmomgZSFj7TanBn8_qXP4ULhCm85abJ5=2PcikXJkrH6GQ@mail.gmail.com>
 <CAN1F8qU8AJ+Z-Rb4+wGsYWd_bS5aOA3bsjd5NjF46MUvnecSeQ@mail.gmail.com>
 <mailman.7473.1393598638.18130.python-list@python.org>
 <XnsA2E95FA1E1EB6duncanbooth@127.0.0.1>
 <bnvctpF5vanU1@mid.individual.net>
 <mailman.7920.1394252278.18130.python-list@python.org>
 <87eh2d3x8h.fsf_-_@elektro.pacujo.net>
 <CAGGBd_qU3Zp3A4pymnDQfWynWZwFVrdHJpG=U0WZTap4HiymdA@mail.gmail.com>
 <lffv32$mqo$1@ger.gmane.org>
 <mailman.8154.1394846042.18130.python-list@python.org>
 <87mwgoqy4k.fsf@elektro.pacujo.net>
 <mailman.8257.1395170778.18130.python-list@python.org>
 <8738ifqlaw.fsf@elektro.pacujo.net>
 <mailman.8263.1395179161.18130.python-list@python.org>
 <op.xcz0mccp5079vu@gnudebeest>
Message-ID: <CAGGBd_pZcjfrrCdLOrtzWfys5apKceH9O9yn6-TdPkaNS8puBg@mail.gmail.com>

On Wed, Mar 19, 2014 at 7:16 PM, Rhodri James <rhodri at wildebst.org.uk> wrote:
> 65536 is a suspiciously round number.  You might want to double-
> check that there's no 16-bit overflow causing something unexpected.

It's because I'm using powers of 2.  All the numbers in the report are
round in hex.


From wtz_wh at foxmail.com  Thu Mar 20 01:51:41 2014
From: wtz_wh at foxmail.com (=?gb18030?B?sbGx+dHz?=)
Date: Thu, 20 Mar 2014 13:51:41 +0800
Subject: [Python-Dev] Issues about relative& absolute import way for
 Portingfrom python2.4 to python2.7
Message-ID: <tencent_2BE3693E682BB54F2047A4BE@qq.com>

Dear,


I just wrote a sample like this:
testPy/
         __init__.py
         client.py
         SoamFactory.c
         SoamFactory.so
         soamapi.py
         sample/testP.py
export PYTHONPATH=$(TEST_LOCATION):$(TEST_LOCATION)/testPy
Here's the source codes:
__init__.py:
import client
client.py
import soamapi
class Client(soamapi.SessionCallback):


  def __init__(self):
    print "----class Client----"
    super(Client, self).__init__()
    soamapi.initialize()


  def create_session(self):
    sec_cb = soamapi.DefaultSecurityCallback()
    self.connection = soamapi.connect(sec_cb)

soamapi.py
import SoamFactory


class ConnectionSecurityCallback(object):  
  def __init__(self):
    print "----class ConnectionSecurityCallback----"


  def __del__(self):
    pass


  def test_P(self):
    print "test_P in class ConnectionSecurityCallback"


class DefaultSecurityCallback(ConnectionSecurityCallback):
  def __init__(self):
    super(DefaultSecurityCallback, self).__init__()
    print "----class DefaultSecurityCallback----"


  def __del__(self):
    super(DefaultSecurityCallback, self).__del__()


  def test(self):
    print "test in class DefaultSecurityCallback"


class SessionCallback(object):
  def __init__(self):
    pass
  
  def __del__(self):
    pass


def connect(security_callback):
  return SoamFactory.SoamFactory_connect(security_callback)


def initialize():
  SoamFactory.SoamFactory_initialize()


print "call soamapi"

SoamFactory.c
#include "Python.h"
#include "PythonLoop.c"


PyObject* SOAM_API_MODULE = NULL;
PyObject* pyModule = NULL;


static PyObject* SoamFactory_initialize(PyObject* self, PyObject* args){
    PyEval_InitThreads();
    init();
    Py_RETURN_NONE;
}


static PyObject* SoamFactory_connect(PyObject* self, PyObject* args){
    PyObject* pySecCallback = NULL;
    int ok = PyArg_ParseTuple(args, "O", &pySecCallback);
    if (!ok){
        printf("parse tuple error!\n");
        Py_RETURN_NONE;
    }
    if (! PyObject_IsInstance(pySecCallback, connectSecCallback)){
        printf("pySecCallback is not an instance of ConnectionSecurityCallback!\n");
        Py_RETURN_NONE;
    }
    printf("Successful!\n");
    Py_RETURN_NONE;
}


static PyMethodDef SoamFactory[] = {
    {"SoamFactory_connect", SoamFactory_connect, METH_VARARGS, "connection function"},
    {"SoamFactory_initialize", SoamFactory_initialize, METH_VARARGS, "SoamFactory_initialize"},
    {NULL, NULL}
};


void initSoamFactory(){
    PyEval_InitThreads();
    Py_Initialize();
    pyModule = Py_InitModule("SoamFactory", SoamFactory);
    SOAM_API_MODULE = PyImport_ImportModule("soamapi");
}

sample/testP.py
import testPy


print "========================================"
submitter = testPy.client.Client()
submitter.create_session()
print "========================================"



When I ran it on python2.4, it worked well, and the result was
call soamapi
after import soamapi------client.py
========================================
----class Client----
----class ConnectionSecurityCallback----
----class DefaultSecurityCallback----
Successful!
========================================   
     
But when I ran it on python2.7, it worked beyond my expectation, the result was 
call soamapi
call soamapi
========================================
----class Client----
----class ConnectionSecurityCallback----
----class DefaultSecurityCallback----
pySecCallback is not an instance of ConnectionSecurityCallback!
========================================



I found that soamapi was imported twice, and I investigated this is related to absolute&relative import way.  PyImport_ImportModule in python2.7 uses absolute import way, it will look up sys.path to get soamapi module, and when testP.py file import testPy module, it will find local module soamapi under testPy package, and binds module's name to package, as testPy.soamapi.
There are two ways to correct it for python2.7, 1) Don't use import testPy, use import client directly to avoid using relative; 2) Use from __future__ import absolute_import to enable absolute import feature.


But there are two Pre-conditions:
1) Should not modify testP.py;
2) Should be ran on both python2.4 and 2.7.


I don't know how to fix it. Is there any official way about how to porting this scenario or better idea?


Thanks,
Vatel
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From frank at chagford.com  Thu Mar 20 02:48:22 2014
From: frank at chagford.com (Frank Millman)
Date: Thu, 20 Mar 2014 08:48:22 +0200
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org> <lgbe6g$j9o$1@ger.gmane.org>
Message-ID: <lge2v9$h0l$1@ger.gmane.org>

"Frank Millman" <frank at chagford.com> wrote in message 
news:lgbe6g$j9o$1 at ger.gmane.org...
>
>
> To recap my basic setup, I have machine A which holds the source 
> directory, machine B which is used to edit the program, and machines B and 
> C which are both used to run the program.
>
> Initially, to prove that I understand the concept, I propose to install 
> Mercurial on all three machines. Machine A will hold the central 
> repository, which I will clone onto machines B and C. After editing on B, 
> I will 'push' to A, and then from C 'pull' from A to get the latest 
> version.
>

Ok, I did that, and it worked. I think I may be on the path to 
enlightenment.

One thing still confuses me. Over the lifetime of a project, there could be 
many thousands of changesets. Some of those could be tagged as 'major 
releases'. Someone wishing to clone the project from scratch may want to 
start from the latest major release, and not download every changeset since 
the project started.

How is this handled in practice?

Thanks

Frank





From rosuav at gmail.com  Thu Mar 20 03:15:25 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 20 Mar 2014 18:15:25 +1100
Subject: Question about Source Control
In-Reply-To: <lge2v9$h0l$1@ger.gmane.org>
References: <lg6s09$irl$1@ger.gmane.org> <lgbe6g$j9o$1@ger.gmane.org>
 <lge2v9$h0l$1@ger.gmane.org>
Message-ID: <CAPTjJmqiAL8TR-9p0zP7k3OyuQ20Lm0YFj9+aObD=eF2BfcRyw@mail.gmail.com>

On Thu, Mar 20, 2014 at 5:48 PM, Frank Millman <frank at chagford.com> wrote:
> One thing still confuses me. Over the lifetime of a project, there could be
> many thousands of changesets. Some of those could be tagged as 'major
> releases'. Someone wishing to clone the project from scratch may want to
> start from the latest major release, and not download every changeset since
> the project started.
>
> How is this handled in practice?

There are several ways, but the most common is to simply tag a
revision along the way; Pike does this, and I do the same in Gypsum.

Pike 7.8.700 is commit 1ace5c:
http://pike-git.lysator.liu.se/gitweb.cgi?p=pike.git;a=commit;h=1ace5c8e7c5c14fcaeeefd307b1ec99b80560311

Gypsum 1.1.0 is commit d937bf:
https://github.com/Rosuav/Gypsum/tree/v1.1.0

You can then offer a non-source-control means of downloading that
specific revision. Github does this for me automatically:

https://github.com/Rosuav/Gypsum/archive/v1.1.0.zip

Pike goes further and publishes binaries for various systems, too, and
the source archive isn't quite a pure snapshot of git at that point
(it has some intermediate files so as to reduce dependencies), but the
effect is the same - if you want to get Pike 7.8.700, you don't need
all the changes:

http://pike.lysator.liu.se/download/pub/pike/latest-stable/

Python also snapshots like that, but with a much more complicated
history than either of the above; the Python download pages offer you
source tarballs and compiled binaries. If you want to find version
3.3.1 in source control, just look that up in the .hgtags file, which
says that "v3.3.1" is d9893d. (I'm not familiar with hg-web, so I
can't provide a link. But it's effectively the same as I showed
above.)

ChrisA


From __peter__ at web.de  Thu Mar 20 03:21:03 2014
From: __peter__ at web.de (Peter Otten)
Date: Thu, 20 Mar 2014 08:21:03 +0100
Subject: [Python-Dev] Issues about relative& absolute import way for
 Portingfrom python2.4 to python2.7
References: <tencent_2BE3693E682BB54F2047A4BE@qq.com>
Message-ID: <lge4sn$63e$1@ger.gmane.org>

??? wrote:

> I just wrote a sample like this:
> testPy/
>          __init__.py
>          client.py
>          SoamFactory.c
>          SoamFactory.so
>          soamapi.py
>          sample/testP.py
> export PYTHONPATH=$(TEST_LOCATION):$(TEST_LOCATION)/testPy

> I found that soamapi was imported twice, and I investigated this is

> I don't know how to fix it. Is there any official way about how to porting
> this scenario or better idea?

Without looking into the details -- I believe that your problem stems from 
having a path into the package:

> export PYTHONPATH=$(TEST_LOCATION):$(TEST_LOCATION)/testPy

The above means that a module testPy.foo can also successfully be imported 
as foo. Try changing the path to

export PYTHONPATH=$(TEST_LOCATION)

If you get failing imports change every failing import

import foo

to

from testPy import foo



From dieter at handshake.de  Thu Mar 20 04:20:03 2014
From: dieter at handshake.de (dieter)
Date: Thu, 20 Mar 2014 09:20:03 +0100
Subject: Problem with pickle and restarting a program
References: <cc656034-01c4-430c-84f0-a181cef6560a@googlegroups.com>
Message-ID: <8738idjn7w.fsf@handshake.de>

Peace <abhishek1899 at gmail.com> writes:
> ...
> The serial number field always remains empty even though I enter from the GUI and the receiveSerialNumber function is called and I explicitly initialize it to the variable in the model.
> I'm trying to save the state of the program so that next time I open the application it resumes from where it left off. The problem is when I restart the application, the serial number is empty. What am I doing wrong here? Whenever I get a change in state (the RC value), I pickle and save to a file (restoreinfo.p). When I restart the application, the serial number is no longer there even though I enter it. Could you please let me know what is going wrong? Thank you.

You may want to use debugging to determine what goes on in detail.

There are commercial debuggers with a graphical user interface
(maybe even free ones). Python comes with a simple command line
debugger ("pdb").



From murukessanap at gmail.com  Thu Mar 20 05:19:55 2014
From: murukessanap at gmail.com (muru kessan)
Date: Thu, 20 Mar 2014 14:49:55 +0530
Subject: Decorator
Message-ID: <CACk27ULPKOaYzU404yanq7e=4qZMhBgk24LwmVZJ=gZz51wQJQ@mail.gmail.com>

Hi guys,
    Is there a difference between accessing decorators via '@' symbol and
hard coding that ? esp when the function passed to the decorator is a
recursive one?

See attachments
result from deco_with@ is
1 1 0 1 1 0 1 1 0

result from deco_without@ is
1 1 2 3 5 8 13 21 34
1 1 0 3 5 0 13 21 0

Thanks ,
muru
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#-------------------------------------------------------------------------------
# Name:        module1
# Purpose:
#
# Author:      Ratna
#
# Created:     20/03/2014
# Copyright:   (c) Ratna 2014
# Licence:     <your licence>
#-------------------------------------------------------------------------------
import math

def isOddMy(func):
    def innerOdd(x):
        y = func(x)
        if math.fmod(y, 2) == 0 :
            return 0
        else:
            if y is not None:
                 return y
            else:
                 return 0
    return innerOdd

@isOddMy
def fib(n):
    #print n,
    if n == 0 :
        return 0
    elif n == 1 :
        return 1
    else:
        return fib(n-2) + fib(n-1)


def main():
    #oddFibi = isOdd(fib)
    #print [i for i in oddFibi(100)]
    for i in range(1,10):
        print fib(i),

    '''print
    fib1 = isOddMy(fib)
    for i in range(1,10):
        print fib1(i),'''

if __name__ == '__main__':
    main()
-------------- next part --------------
#-------------------------------------------------------------------------------
# Name:        module1
# Purpose:
#
# Author:      Ratna
#
# Created:     20/03/2014
# Copyright:   (c) Ratna 2014
# Licence:     <your licence>
#-------------------------------------------------------------------------------
import math

def isOddMy(func):
    def innerOdd(x):
        y = func(x)
        if math.fmod(y, 2) == 0 :
            return 0
        else:
            if y is not None:
                 return y
            else:
                 return 0
    return innerOdd

#@isOddMy
def fib(n):
    #print n,
    if n == 0 :
        return 0
    elif n == 1 :
        return 1
    else:
        return fib(n-2) + fib(n-1)


def main():
    #oddFibi = isOdd(fib)
    #print [i for i in oddFibi(100)]
    for i in range(1,10):
        print fib(i),

    print
    fib1 = isOddMy(fib)
    for i in range(1,10):
        print fib1(i),

if __name__ == '__main__':
    main()

From __peter__ at web.de  Thu Mar 20 05:59:35 2014
From: __peter__ at web.de (Peter Otten)
Date: Thu, 20 Mar 2014 10:59:35 +0100
Subject: Decorator
References: <CACk27ULPKOaYzU404yanq7e=4qZMhBgk24LwmVZJ=gZz51wQJQ@mail.gmail.com>
Message-ID: <lgee5r$ffp$1@ger.gmane.org>

muru kessan wrote:

>     Is there a difference between accessing decorators via '@' symbol and
> hard coding that ? esp when the function passed to the decorator is a
> recursive one?

The difference is not the decorator but the recursive function call. 
Consider

Case 1:

@deco
def f():
   ...
   f() # calls the decorated function
   ...
f()

Case 2:

def f()
    ...
    f() # calls the undecorated function
    ...
g = deco(f)
g()


The function call f() will invoke whatever the global name f is bound to a 
the time of invocation. So

Case 3:

def f()
    ...
    f() # calls the decorated function
    ...
f = deco(f)
f()

In your code change 

fib1 = isOddMy(fib)

to

fib = isOddMy(fib)

and the without@ version will produce the same output as the with@ version.



From davea at davea.name  Thu Mar 20 07:00:44 2014
From: davea at davea.name (Dave Angel)
Date: Thu, 20 Mar 2014 07:00:44 -0400 (EDT)
Subject: Decorator
References: <CACk27ULPKOaYzU404yanq7e=4qZMhBgk24LwmVZJ=gZz51wQJQ@mail.gmail.com>
 <lgee5r$ffp$1@ger.gmane.org>
Message-ID: <lgehfh$nfh$1@ger.gmane.org>

 Peter Otten <__peter__ at web.de> Wrote in message:

> 
> In your code change 
> 
> fib1 = isOddMy(fib)
> 
> to
> 
> fib = isOddMy(fib)
> 
> and the without@ version will produce the same output as the with@ version.
> 
> 

I expect that one more thing is needed,  since the above is inside
 a function:

     global fib
     fib = isOdd (fib)

-- 
DaveA



From fabiofz at gmail.com  Thu Mar 20 08:01:50 2014
From: fabiofz at gmail.com (Fabio Zadrozny)
Date: Thu, 20 Mar 2014 09:01:50 -0300
Subject: PyDev 3.4.1 Released
Message-ID: <CANXBEFogXsze6WByg_iCit-oLEQK-RXsgJCDM=ocZ7JPNgdb8g@mail.gmail.com>

What is PyDev?
---------------------------

PyDev is an open-source Python IDE on top of Eclipse for Python, Jython and
IronPython development.

It comes with goodies such as code completion, syntax highlighting, syntax
analysis, code analysis, refactor, debug, interactive console, etc.

Details on PyDev: http://pydev.org
Details on its development: http://pydev.blogspot.com


What is LiClipse?
---------------------------

LiClipse is a PyDev standalone with goodies such as support for Multiple
cursors, theming and a number of other languages such as Django Templates,
Kivy Language, Mako Templates, Html, Javascript, etc.

It's also a commercial counterpart which helps supporting the development
of PyDev.

Details on LiClipse: http://brainwy.github.io/liclipse/


Release Highlights:
-------------------------------

- **Important**: PyDev requires Eclipse 3.8 or 4.3 onwards and Java 7! For
older versions, keep using PyDev 2.x (or LiClipse for a PyDev standalone
with all requirements bundled).


- **Interactive Console**:

    * **Send a single line to the interactive console with F2** (akin to
Ctrl+Alt+Enter but only for the current line).


- **Debugger**:

    * **Added support for debugging spawned subprocesses.**

    * New Django launches no longer have -noreload to take advantage of
that (but existing launches have to be manually edited -- or removed and
recreated).

    * When terminating a process its subprocesses are also killed (avoiding
django zombie processes).

    * In the debugger, locals are now also properly saved on PyPy (requires
a newer version of PyPy too).

    * Remote Debugger: when specifying items in
PATHS_FROM_ECLIPSE_TO_PYTHON pathnames are normalized.

    * Fixes to work with Jython 2.1 and Jython 2.2.1

    * Always setting PYTHONUNBUFFERED environment variable to 1.

    * The python default encoding is no longer changed (only
PYTHONIOENCODING is used now and not sys.setdefaultencoding).

    * Minor improvements on get referrers.


- **General**:

    * **Cython: .pxd and .pxi files are properly supported.**

    * Interpreter configuration: It's possible to reorder PYTHONPATH
entries with drag and drop.

    * Fixed django interactive shell to work with newer versions of Django.

    * Rename working properly for files without extensions.

    * Fixed issue where specifying the type of a variable with a comment
was not detected in the code-completion.

    * Fixed issue where we'd open a file as if it was an external file when
it was actually a file in the workspace or inside a source folder.

    * PyDev Package Explorer: fixed issue where some errors would remain
showing when they didn't exist anymore.

    * PyDev Package Explorer: fixed issue where items could change its
order depending on decorations.

    * On a double-click on spaces, all the spaces are selected.


- **Test Runner**:

    * **Improved py.test integration**: it's now possible to select which
tests to run with Ctrl+F9 (even if not under a class).

    * No longer breaks if a file which was in a launch config is removed
(still runs other tests in the launch).

    * After a test run finishes, if there are non-daemon threads running
they're printed to the output.

    * Fixed UnicodeDecodeError when running unit-tests under python 2.x

    * Fixed issue on test discovery on Linux.


- **Sorting Imports**:

    * Sort of imports no longer adds spaces at end of imports.

    * Sort of imports no longer passes the number of available columns
specified.

    * It's now also possible to keep the names of 'from' imports sorted.



Cheers,

--
Fabio Zadrozny
------------------------------------------------------
Software Developer

LiClipse
http://brainwy.github.io/liclipse

PyDev - Python Development Environment for Eclipse
http://pydev.org
http://pydev.blogspot.com
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From __peter__ at web.de  Thu Mar 20 09:04:33 2014
From: __peter__ at web.de (Peter Otten)
Date: Thu, 20 Mar 2014 14:04:33 +0100
Subject: Decorator
References: <CACk27ULPKOaYzU404yanq7e=4qZMhBgk24LwmVZJ=gZz51wQJQ@mail.gmail.com>
 <lgee5r$ffp$1@ger.gmane.org> <lgehfh$nfh$1@ger.gmane.org>
Message-ID: <lgep0i$hel$1@ger.gmane.org>

Dave Angel wrote:

>  Peter Otten <__peter__ at web.de> Wrote in message:
> 
>> 
>> In your code change
>> 
>> fib1 = isOddMy(fib)
>> 
>> to
>> 
>> fib = isOddMy(fib)
>> 
>> and the without@ version will produce the same output as the with@
>> version.
>> 
>> 
> 
> I expect that one more thing is needed,  since the above is inside
>  a function:
> 
>      global fib
>      fib = isOdd (fib)

Yes, sorry, I missed that. 




From ishish at domhain.de  Thu Mar 20 09:11:44 2014
From: ishish at domhain.de (ishish)
Date: Thu, 20 Mar 2014 13:11:44 +0000
Subject: Dictionaries
In-Reply-To: <CANXBEFogXsze6WByg_iCit-oLEQK-RXsgJCDM=ocZ7JPNgdb8g@mail.gmail.com>
References: <CANXBEFogXsze6WByg_iCit-oLEQK-RXsgJCDM=ocZ7JPNgdb8g@mail.gmail.com>
Message-ID: <cc9658ed24ed4af1b65b5098a00f9aac@home.minuskel.de>

Hi,

This might sound weird, but is there a limit how many dictionaries a 
can create/use in a single script?

My reason for asking is I split a 2-column-csv (phone#, ref#) file into 
a dict and am trying to put duplicated phone numbers with different ref 
numbers into new dictionaries. The script deducts the duplicated 46 
numbers but it only creates batch1.csv. Since I obviously can't see the 
wood for the trees here, can someone pls punch me into the right 
direction....
...(No has_key is fine, its python 2.7)

f = open("file.csv", 'r')

myDict = {}
Batch1 = {}
Batch2 = {}
Batch3 = {}

for line in f:
	if line.startswith('Number' ):
		print "First line ignored..."
	else:
		k, v = line.split(',')
		myDict[k] = v
f.close()

for k, v in myDict.items():
	if Batch1.has_key(k):
		if k in Batch2.has_key(k):
			Batch3[k] = v
		else:
			Batch2[k] = v
	else:
		Batch1[k] = v

for k, v in Batch1.items():
	newLine = "%s,%s" % (k, v)
	with open("batch1.csv", "a") as f:
		f.write(newLine)

for k, v in Batch2.items():
	newLine = "%s,%s" % (k, v)
	with open("batch2.csv", "a") as f:
		f.write(newLine)

for k, v in Batch3.items():
	newLine = "%s,%s" % (k, v)
	with open("batch3.csv", "a") as f:
		f.write(newLine)


From __peter__ at web.de  Thu Mar 20 10:08:31 2014
From: __peter__ at web.de (Peter Otten)
Date: Thu, 20 Mar 2014 15:08:31 +0100
Subject: Dictionaries
References: <CANXBEFogXsze6WByg_iCit-oLEQK-RXsgJCDM=ocZ7JPNgdb8g@mail.gmail.com>
 <cc9658ed24ed4af1b65b5098a00f9aac@home.minuskel.de>
Message-ID: <lgesoi$8a1$1@ger.gmane.org>

ishish wrote:

> This might sound weird, but is there a limit how many dictionaries a 
> can create/use in a single script?

No.
 
> My reason for asking is I split a 2-column-csv (phone#, ref#) file into 
> a dict and am trying to put duplicated phone numbers with different ref 
> numbers into new dictionaries. The script deducts the duplicated 46 
> numbers but it only creates batch1.csv. Since I obviously can't see the 
> wood for the trees here, can someone pls punch me into the right 
> direction....
> ...(No has_key is fine, its python 2.7)
> 
> f = open("file.csv", 'r')

Consider a csv with the lines

Number...
123,first
123,second
456,third
 
> myDict = {}
> Batch1 = {}
> Batch2 = {}
> Batch3 = {}
> 
> for line in f:
>         if line.startswith('Number' ):
>                 print "First line ignored..."
>         else:
>                 k, v = line.split(',')
>                 myDict[k] = v

the first time around the assignment is

myDict["123"] = "first\n"

the second time it is

myDict["123"] = "second\n"

i. e. you are overwriting the previous value and only keep the value 
corresponding to the last occurrence of a key.

A good approach to solve the problem of keeping an arbitrary number of 
values per key is to make the dict value a list:

myDict = {}
with open("data.csv") as f:
    next(f) # skip first line
    for line in f:
        k, v = line.split(",")
        myDict.setdefault(k, []).append(v)

This will produce a myDict
{
   "123": ["first\n", "second\n"],
   "456": ["third\n"]
}

You can then proceed to find out the number of batches:

num_batches = max(len(v) for v in myDict.values())

Now write the files:

for index in range(num_batches):
    with open("batch%s.csv" % (index+1), "w") as f:
        for key, values in myDict.items():
            if len(values) > index: # there are more than index duplicates
                f.write("%s,%s" % (key, values[index]))




From gordon at panix.com  Thu Mar 20 10:19:50 2014
From: gordon at panix.com (John Gordon)
Date: Thu, 20 Mar 2014 14:19:50 +0000 (UTC)
Subject: Dictionaries
References: <CANXBEFogXsze6WByg_iCit-oLEQK-RXsgJCDM=ocZ7JPNgdb8g@mail.gmail.com>
 <mailman.8300.1395322251.18130.python-list@python.org>
Message-ID: <lgete6$fom$1@reader1.panix.com>

In <mailman.8300.1395322251.18130.python-list at python.org> ishish <ishish at domhain.de> writes:

> The script [...] only creates batch1.csv.

If the script only creates batch1.csv, that means Batch2 and Batch3 must
be empty.

> for k, v in myDict.items():
> 	if Batch1.has_key(k):
> 		if k in Batch2.has_key(k):
> 			Batch3[k] = v
> 		else:
> 			Batch2[k] = v
> 	else:
> 		Batch1[k] = v

'if k in Batch2.has_key(k):' is a very strange line of code.  In fact, it
should produce a syntax error if it were ever executed, because the 'in'
keyword requires an iterable as the second part, and has_key() returns
only True or False.

Therefore, I would say that line of code never executes, which means
that the preceding 'if Batch1.has_key(k)' statement always evaluates
to False.

Which therefore means that Batch2 and Batch3 never accumulate any items,
matching your observed output.

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon at panix.com    watch 'House', or a real serial killer to watch 'Dexter'.



From davea at davea.name  Thu Mar 20 10:44:32 2014
From: davea at davea.name (Dave Angel)
Date: Thu, 20 Mar 2014 10:44:32 -0400 (EDT)
Subject: Dictionaries
References: <CANXBEFogXsze6WByg_iCit-oLEQK-RXsgJCDM=ocZ7JPNgdb8g@mail.gmail.com>
 <cc9658ed24ed4af1b65b5098a00f9aac@home.minuskel.de>
Message-ID: <lgeuj3$qr$1@ger.gmane.org>

 Please don't leave new questions in an existing thread, and
 especially without changing subject line. Compose a new message
 with meaningful subject line. 


ishish <ishish at domhain.de> Wrote in message:
> Hi,
> 
> This might sound weird, but is there a limit how many dictionaries a 
> can create/use in a single script?

No, unless you run out of RAM.

> 
> My reason for asking is I split a 2-column-csv (phone#, ref#) file into 
> a dict and am trying to put duplicated phone numbers with different ref 
> numbers into new dictionaries. The script deducts the duplicated 46 
> numbers but it only creates batch1.csv. Since I obviously can't see the 
> wood for the trees here, can someone pls punch me into the right 
> direction....
> ...(No has_key is fine, its python 2.7)

But has_key is deprecated,  and you're using it wrong anyway. 

> 
> f = open("file.csv", 'r')
> 
> myDict = {}
> Batch1 = {}
> Batch2 = {}
> Batch3 = {}
> 
> for line in f:
> 	if line.startswith('Number' ):
> 		print "First line ignored..."
> 	else:
> 		k, v = line.split(',')
> 		myDict[k] = v
> f.close()
> 
> for k, v in myDict.items():
> 	if Batch1.has_key(k):
> 		if k in Batch2.has_key(k):

I'm surprised this doesn't throw an exception.   has_key returns a
 bool, and in isn't meaningful on a bool.  Just use
 
      if k in Batch2:


> 			Batch3[k] = v
> 		else:
> 			Batch2[k] = v
> 	else:
> 		Batch1[k] = v
> 
> for k, v in Batch1.items():
> 	newLine = "%s,%s" % (k, v)
> 	with open("batch1.csv", "a") as f:

This is unusual,  and a performance killer,  to repeatedly open
 the file.  But you may have some reason. 

> 		f.write(newLine)

There's no newline there, so your csv is going to be one long
 line. You probably want newLine+'\n' inside those
 parens.

> 
> for k, v in Batch2.items():
> 	newLine = "%s,%s" % (k, v)
> 	with open("batch2.csv", "a") as f:
> 		f.write(newLine)
> 
> for k, v in Batch3.items():
> 	newLine = "%s,%s" % (k, v)
> 	with open("batch3.csv", "a") as f:
> 		f.write(newLine)
> 


-- 
DaveA



From notbob at nothome.com  Thu Mar 20 10:58:54 2014
From: notbob at nothome.com (notbob)
Date: 20 Mar 2014 14:58:54 GMT
Subject: running python 2 vs 3
Message-ID: <bp0e1eF613oU1@mid.individual.net>

Dumb noob questions: 

I've installed python 3.3 on my Slack box, which by default comes with
python 2.7.  I know how to fire up the different IDLE environments,
but how do I differentiate between the scripts?  IOW, up till now,
I've used .py on all my 2.7 files.  How do I know not to run a .py in
python3 or visa versa?  Or do I?  What's the excepted convention for
differentiating between the two?

nb  


From ishish at domhain.de  Thu Mar 20 10:15:57 2014
From: ishish at domhain.de (ishish)
Date: Thu, 20 Mar 2014 14:15:57 +0000
Subject: Dictionaries
In-Reply-To: <lgesoi$8a1$1@ger.gmane.org>
References: <CANXBEFogXsze6WByg_iCit-oLEQK-RXsgJCDM=ocZ7JPNgdb8g@mail.gmail.com>
 <cc9658ed24ed4af1b65b5098a00f9aac@home.minuskel.de>
 <lgesoi$8a1$1@ger.gmane.org>
Message-ID: <cc12d990ac025e70540e0dfa5e7b2781@home.minuskel.de>

Thanks Peter for the fast response, but the prob is solved. My 
colleague just verbally slapped me because a dict SHOULDN'T have 
duplicate keys...
I change it around to duplicate values and it works fine....
I think I need coffee now... lots of it.



From marko at pacujo.net  Thu Mar 20 11:21:42 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 20 Mar 2014 17:21:42 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
Message-ID: <87ob10nbeh.fsf@elektro.pacujo.net>

notbob <notbob at nothome.com>:

> I've installed python 3.3 on my Slack box, which by default comes with
> python 2.7. I know how to fire up the different IDLE environments, but
> how do I differentiate between the scripts? IOW, up till now, I've
> used .py on all my 2.7 files. How do I know not to run a .py in
> python3 or visa versa? Or do I? What's the excepted convention for
> differentiating between the two?

That's a bit of a sore spot.

On a linux box, the initial line of the script indicates the
interpreter:

   #!/usr/bin/env python2

for Python 2.x

   #!/usr/bin/env python3

for Python 3.x.

All tutorials will tell you to start it with

   #!/usr/bin/env python

which will start python2 on all (?) existing linux distros, but is
expected to start python3 within the next decade.


Marko


From notbob at nothome.com  Thu Mar 20 12:00:07 2014
From: notbob at nothome.com (notbob)
Date: 20 Mar 2014 16:00:07 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
Message-ID: <bp0hk7F613oU3@mid.individual.net>

On 2014-03-20, Marko Rauhamaa <marko at pacujo.net> wrote:

> That's a bit of a sore spot.
>
> On a linux box, the initial line of the script indicates the
> interpreter:
>
>    #!/usr/bin/env python2
>
> for Python 2.x
>
>    #!/usr/bin/env python3
>
> for Python 3.x.
>
> All tutorials will tell you to start it with
>
>    #!/usr/bin/env python
>
> which will start python2 on all (?) existing linux distros, but is
> expected to start python3 within the next decade.

Ahhh! ....now a shabang I understand.  So, I guess the only way, short
of looking at the actual file, is to include the version in the
filename.  Can I safely assume I can run all 2.7 files w/o a shebang
(which I have not, so far, and was wondering how I got away with that)
and only include a py3 shebang in the py3 files, yes/no?  

nb


From harrismh777 at gmail.com  Thu Mar 20 12:11:28 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 20 Mar 2014 11:11:28 -0500
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
Message-ID: <lgf3ve$iuc$1@speranza.aioe.org>

On 3/20/14 9:58 AM, notbob wrote:

> I've installed python 3.3 on my Slack box, which by default comes with
> python 2.7.  I know how to fire up the different IDLE environments,
> but how do I differentiate between the scripts?

hi notbob, the two (or more) IDLE environments run very nicely 
side-by-side. If you access your scripts from the same directory (I do 
not) there really is no problem. The reason is that the .pyc files 
created for python2.x are only used by python2.  The .pyc files for 
python3.x are kept (by a naming convention) in __pycache__ , so there 
really is no problem.  Having said that, the only problem is that your 
script for python3 might not run in python2 (for various reasons) but 
the problem is not that the scripts are contained in the same folder.

I keep my python2 scripts in one folder ~/Documents/Python2/ and my 
python3 scripts in another one ~/Documents/Python3/

I add the two folders in the python paths browser (using site-packages) 
so that when I start IDLE for python2 it pulls its scripts from 
~/Documents/Python2/  and when I start IDLE for python3 it pulls its 
scripts from  ~/Documents/Python3/

There are *many* ways to organize this. Often I have to maintain two 
scripts (packages) one for each version. Although, I try to make my 
scripts run in both environments.  Often I have IDLE(2) ane IDLE(3) 
running and testing at the same time on the same box. This works very well.

marcus



From zachary.ware+pylist at gmail.com  Thu Mar 20 12:14:54 2014
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Thu, 20 Mar 2014 11:14:54 -0500
Subject: running python 2 vs 3
In-Reply-To: <bp0hk7F613oU3@mid.individual.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
 <bp0hk7F613oU3@mid.individual.net>
Message-ID: <CAKJDb-PpnB5ALvodfQL+0Oke5XRQd0BD0T_GJ8fkJ7F5AyqMAQ@mail.gmail.com>

On Thu, Mar 20, 2014 at 11:00 AM, notbob <notbob at nothome.com> wrote:
> Ahhh! ....now a shabang I understand.  So, I guess the only way, short
> of looking at the actual file, is to include the version in the
> filename.  Can I safely assume I can run all 2.7 files w/o a shebang
> (which I have not, so far, and was wondering how I got away with that)
> and only include a py3 shebang in the py3 files, yes/no?

If I understand your question: you're probably better off putting a
shebang line in all of the files that you intend to run directly.  Use
"/usr/bin/env python2" for your Python 2 scripts, "/usr/bin/env
python3" for your Python 3 scripts, and "/usr/bin/env python" for
scripts that can run under either interpreter.  You can also be more
version-specific if you need to; use "python2.7", "python3.3", etc. as
necessary.  That way, you can invoke the script directly and the right
interpreter will run it.  If you're specifying the interpreter in your
command (by calling "python <scriptname>.py", etc), the shebang won't
mean anything anyway.

-- 
Zach


From notbob at nothome.com  Thu Mar 20 13:10:42 2014
From: notbob at nothome.com (notbob)
Date: 20 Mar 2014 17:10:42 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <bp0hk7F613oU3@mid.individual.net>
 <mailman.8304.1395332703.18130.python-list@python.org>
Message-ID: <bp0lohF7aqdU3@mid.individual.net>

On 2014-03-20, Zachary Ware <zachary.ware+pylist at gmail.com> wrote:

> If you're specifying the interpreter in your command (by calling
> "python <scriptname>.py", etc), the shebang won't mean anything
> anyway.

DOH!  

I was following you, fine, until that last sentence.  Then how should
I invoke the scripts? ....as your example is exactly how I've been
doing it with 2.7, as per Learn Python the Hard Way.  Simply
./<scriptname>.py from the appropriate directory (assuming I keep both
vers in separate dirs)?

nb


From notbob at nothome.com  Thu Mar 20 13:23:24 2014
From: notbob at nothome.com (notbob)
Date: 20 Mar 2014 17:23:24 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net> <lgf3ve$iuc$1@speranza.aioe.org>
Message-ID: <bp0mgcF7aqdU4@mid.individual.net>

On 2014-03-20, Mark H Harris <harrismh777 at gmail.com> wrote:

> not) there really is no problem. The reason is that the .pyc files 
> created for python2.x are only used by python2.  

Lordy, what hath I wrought!?  ;)

What the heck is a .pyc file and how are they created?  Actually, I
can see  it's a compiled binary, but I where did it come from?  

I went back to my ~/python/ dir and noticed one .pyc file out of 15
.py files I created from following Learning Python the Hard Way.  No
one said anything about creating a binary.  I know I discovered how to
create/edit python scripts from IDLE.  Is that it?  I've been using
gedit and emacs up till now.  Seems the file with the .pyc file is the
one I edited in IDLE.  Is that why LPtHW eschews IDLE for gedit?  

Why do I feel like I've really stepped in it?  ;)

nb


From rosuav at gmail.com  Thu Mar 20 13:29:54 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 04:29:54 +1100
Subject: running python 2 vs 3
In-Reply-To: <bp0mgcF7aqdU4@mid.individual.net>
References: <bp0e1eF613oU1@mid.individual.net> <lgf3ve$iuc$1@speranza.aioe.org>
 <bp0mgcF7aqdU4@mid.individual.net>
Message-ID: <CAPTjJmoecLz08RFCZY2A2a6EvMFddFwoYt+d5AEz-DuiAmE6MQ@mail.gmail.com>

On Fri, Mar 21, 2014 at 4:23 AM, notbob <notbob at nothome.com> wrote:
> On 2014-03-20, Mark H Harris <harrismh777 at gmail.com> wrote:
>
>> not) there really is no problem. The reason is that the .pyc files
>> created for python2.x are only used by python2.
>
> Lordy, what hath I wrought!?  ;)
>
> What the heck is a .pyc file and how are they created?  Actually, I
> can see  it's a compiled binary, but I where did it come from?
>
> I went back to my ~/python/ dir and noticed one .pyc file out of 15
> .py files I created from following Learning Python the Hard Way.  No
> one said anything about creating a binary.  I know I discovered how to
> create/edit python scripts from IDLE.  Is that it?  I've been using
> gedit and emacs up till now.  Seems the file with the .pyc file is the
> one I edited in IDLE.  Is that why LPtHW eschews IDLE for gedit?
>
> Why do I feel like I've really stepped in it?  ;)
>

You should be able to completely ignore .pyc files, most of the time.
The only thing to remember is that you should delete them any time you
delete the corresponding .py files. They're a cached version that
Python will use to speed up imports, nothing more.

Nowadays they'll be pushed away into a separate directory, which makes
them easier for you to ignore. This is a good thing.

ChrisA


From rosuav at gmail.com  Thu Mar 20 13:30:58 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 04:30:58 +1100
Subject: running python 2 vs 3
In-Reply-To: <bp0lohF7aqdU3@mid.individual.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
 <bp0hk7F613oU3@mid.individual.net>
 <mailman.8304.1395332703.18130.python-list@python.org>
 <bp0lohF7aqdU3@mid.individual.net>
Message-ID: <CAPTjJmoHu4by9bNw26_oL52mjgXi9JiYX9Pk5QEWk_WV0ZyoTQ@mail.gmail.com>

On Fri, Mar 21, 2014 at 4:10 AM, notbob <notbob at nothome.com> wrote:
> On 2014-03-20, Zachary Ware <zachary.ware+pylist at gmail.com> wrote:
>
>> If you're specifying the interpreter in your command (by calling
>> "python <scriptname>.py", etc), the shebang won't mean anything
>> anyway.
>
> DOH!
>
> I was following you, fine, until that last sentence.  Then how should
> I invoke the scripts? ....as your example is exactly how I've been
> doing it with 2.7, as per Learn Python the Hard Way.  Simply
> ./<scriptname>.py from the appropriate directory (assuming I keep both
> vers in separate dirs)?

That's a fine way to do it. Zachary is mentioning an alternative, and
showing that the shebang doesn't hurt (it's a comment to Python), so
go ahead and put the shebang in all your scripts.

ChrisA


From harrismh777 at gmail.com  Thu Mar 20 13:42:05 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 20 Mar 2014 12:42:05 -0500
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <lgf3ve$iuc$1@speranza.aioe.org> <bp0mgcF7aqdU4@mid.individual.net>
Message-ID: <lgf99a$3fc$1@speranza.aioe.org>

On 3/20/14 12:23 PM, notbob wrote:

> What the heck is a .pyc file and how are they created?  Actually, I
> can see  it's a compiled binary, but I where did it come from?

The world according to me:  python is an interpreter (vs compiler) which 
converts your source code into tokens and then into a bytecode.

The process takes time. So, the solution is to place the tokenized stuff 
into a .pyc file so that the process does not have to be repeated 
unless, of course, the source has changed since the last .pyc file create.

It used to be that the .pyc files went into the same dir as the source 
(that's how it works for python2) but now with python3 they go into a 
directory in your source tree called __pycache__,  and they are named 
based on python version  (a way better scheme for sure).

If you wanted to you could run your python scripts from the .pyc file 
alone. In other words, you may import as long as the .pyc file exists 
and the source does not need to be there.  Some folks use this (not 
recommended) trick to hide or obfuscate their source from their users).

marcus




From marko at pacujo.net  Thu Mar 20 13:45:43 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 20 Mar 2014 19:45:43 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <lgf3ve$iuc$1@speranza.aioe.org> <bp0mgcF7aqdU4@mid.individual.net>
 <mailman.8305.1395336598.18130.python-list@python.org>
Message-ID: <87k3bon4qg.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Nowadays they'll be pushed away into a separate directory, which makes
> them easier for you to ignore. This is a good thing.

Still, I don't think Python should go and soil my directories without an
explicit permission.


Marko


From marko at pacujo.net  Thu Mar 20 13:47:10 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 20 Mar 2014 19:47:10 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <lgf3ve$iuc$1@speranza.aioe.org> <bp0mgcF7aqdU4@mid.individual.net>
 <lgf99a$3fc$1@speranza.aioe.org>
Message-ID: <87fvmcn4o1.fsf@elektro.pacujo.net>

Mark H Harris <harrismh777 at gmail.com>:

> If you wanted to you could run your python scripts from the .pyc file
> alone. In other words, you may import as long as the .pyc file exists
> and the source does not need to be there. Some folks use this (not
> recommended) trick to hide or obfuscate their source from their
> users).

I've seen it done, but at least in those Python 2 days the pyc format
changed between minor releases of Python, so Python itself had to be
shipped with the pyc files.


Marko


From gary.herron at islandtraining.com  Thu Mar 20 13:45:33 2014
From: gary.herron at islandtraining.com (Gary Herron)
Date: Thu, 20 Mar 2014 10:45:33 -0700
Subject: running python 2 vs 3
In-Reply-To: <bp0lohF7aqdU3@mid.individual.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <bp0hk7F613oU3@mid.individual.net>
 <mailman.8304.1395332703.18130.python-list@python.org>
 <bp0lohF7aqdU3@mid.individual.net>
Message-ID: <532B293D.4030602@islandtraining.com>

On 03/20/2014 10:10 AM, notbob wrote:
> On 2014-03-20, Zachary Ware <zachary.ware+pylist at gmail.com> wrote:
>
>> If you're specifying the interpreter in your command (by calling
>> "python <scriptname>.py", etc), the shebang won't mean anything
>> anyway.
> DOH!
>
> I was following you, fine, until that last sentence.  Then how should
> I invoke the scripts? ....as your example is exactly how I've been
> doing it with 2.7, as per Learn Python the Hard Way.  Simply
> ./<scriptname>.py from the appropriate directory (assuming I keep both
> vers in separate dirs)?
>
> nb

If you mark your script as executable (chmod ...) and include the 
shebang line, and place it in a directory included in your search path 
(mine is ~/bin),  then you run it as you run any installed program:  
Just type it's name followed by any command line args.   I usually 
remove the .py portion of the name as I copy it into my bin directory so 
it really does look like any other installed program.

If you need to be in a specific directory when you run it, then perhaps 
you should consider a bit of a rewrite to remove this constraint.

Gary Herron


From laguna-mc at mail.com  Thu Mar 20 14:22:19 2014
From: laguna-mc at mail.com (laguna-mc at mail.com)
Date: Thu, 20 Mar 2014 14:22:19 -0400
Subject: Installing ssdeep on Portable Python
Message-ID: <20140320182219.240120@gmx.com>

Portable Python 2.7 for Windows, the Python application have dependency on ssdeep-2.10, which is a binary exe.

The ssdeep (libfuzzy) installation example was shown for Linux platform only:
----
a) libfuzzy can be installed via apt-get:

 ? ?$ sudo apt-get install libfuzzy2

b) to install libfuzzy from source, download the gzipped tarball from http://ssdeep.sourceforge.net/#download, then run:

 ? ?$ tar -zxvf ssdeep-2.10.tar.gz
 ? ?$ cd ssdeep-2.10 && ./configure && make && sudo make install
-----
I need install it on PortablePython for Windows, so it's not clear how to make this: where should be placed ssdeep Windows binary files, that Python application can found it?
-------------- next part --------------
-- 
https://mail.python.org/mailman/listinfo/python-list

From abhishek1899 at gmail.com  Thu Mar 20 14:28:40 2014
From: abhishek1899 at gmail.com (peace)
Date: Thu, 20 Mar 2014 11:28:40 -0700 (PDT)
Subject: Problem with pickle and restarting a program
In-Reply-To: <mailman.8292.1395303616.18130.python-list@python.org>
References: <cc656034-01c4-430c-84f0-a181cef6560a@googlegroups.com>
 <mailman.8292.1395303616.18130.python-list@python.org>
Message-ID: <11a691c7-2842-4d3a-b355-1e44652d7590@googlegroups.com>

On Thursday, March 20, 2014 1:20:03 AM UTC-7, dieter wrote:
> Peace <> writes:
> 
> > ...
> 
> > The serial number field always remains empty even though I enter from the GUI and the receiveSerialNumber function is called and I explicitly initialize it to the variable in the model.
> 
> > I'm trying to save the state of the program so that next time I open the application it resumes from where it left off. The problem is when I restart the application, the serial number is empty. What am I doing wrong here? Whenever I get a change in state (the RC value), I pickle and save to a file (restoreinfo.p). When I restart the application, the serial number is no longer there even though I enter it. Could you please let me know what is going wrong? Thank you.
> 
> 
> 
> You may want to use debugging to determine what goes on in detail.
> 
> 
> 
> There are commercial debuggers with a graphical user interface
> 
> (maybe even free ones). Python comes with a simple command line
> 
> debugger ("pdb").

I tried doing that. I still could not figure out what was wrong. Thank you.


From ned at nedbatchelder.com  Thu Mar 20 14:45:06 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Thu, 20 Mar 2014 14:45:06 -0400
Subject: running python 2 vs 3
In-Reply-To: <87fvmcn4o1.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <lgf3ve$iuc$1@speranza.aioe.org> <bp0mgcF7aqdU4@mid.individual.net>
 <lgf99a$3fc$1@speranza.aioe.org> <87fvmcn4o1.fsf@elektro.pacujo.net>
Message-ID: <lgfcv3$qi$1@ger.gmane.org>

On 3/20/14 1:47 PM, Marko Rauhamaa wrote:
> Mark H Harris <harrismh777 at gmail.com>:
>
>> If you wanted to you could run your python scripts from the .pyc file
>> alone. In other words, you may import as long as the .pyc file exists
>> and the source does not need to be there. Some folks use this (not
>> recommended) trick to hide or obfuscate their source from their
>> users).
>
> I've seen it done, but at least in those Python 2 days the pyc format
> changed between minor releases of Python, so Python itself had to be
> shipped with the pyc files.
>

Python3 still makes no guarantees about the compatibility of bytecode 
(and therefore .pyc files) across versions of Python, so if you want to 
run from pure .pyc files, you have to be sure to use the same version of 
Python that produced the files.

--Ned.

>
> Marko
>


-- 
Ned Batchelder, http://nedbatchelder.com



From breamoreboy at yahoo.co.uk  Thu Mar 20 14:56:25 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 20 Mar 2014 18:56:25 +0000
Subject: running python 2 vs 3
In-Reply-To: <87ob10nbeh.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
Message-ID: <lgfdke$55s$1@ger.gmane.org>

On 20/03/2014 15:21, Marko Rauhamaa wrote:
> notbob <notbob at nothome.com>:
>
>> I've installed python 3.3 on my Slack box, which by default comes with
>> python 2.7. I know how to fire up the different IDLE environments, but
>> how do I differentiate between the scripts? IOW, up till now, I've
>> used .py on all my 2.7 files. How do I know not to run a .py in
>> python3 or visa versa? Or do I? What's the excepted convention for
>> differentiating between the two?
>
> That's a bit of a sore spot.
>
> On a linux box, the initial line of the script indicates the
> interpreter:
>
>     #!/usr/bin/env python2
>
> for Python 2.x
>
>     #!/usr/bin/env python3
>
> for Python 3.x.
>
> All tutorials will tell you to start it with
>
>     #!/usr/bin/env python
>
> which will start python2 on all (?) existing linux distros, but is
> expected to start python3 within the next decade.
>
>
> Marko
>

The above is also true on windows via the 'Python launcher for windows' 
see http://legacy.python.org/dev/peps/pep-0397/

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From gordon at panix.com  Thu Mar 20 15:07:39 2014
From: gordon at panix.com (John Gordon)
Date: Thu, 20 Mar 2014 19:07:39 +0000 (UTC)
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <bp0hk7F613oU3@mid.individual.net>
 <mailman.8304.1395332703.18130.python-list@python.org>
 <bp0lohF7aqdU3@mid.individual.net>
Message-ID: <lgfe9q$9hv$1@reader1.panix.com>

In <bp0lohF7aqdU3 at mid.individual.net> notbob <notbob at nothome.com> writes:

> On 2014-03-20, Zachary Ware <zachary.ware+pylist at gmail.com> wrote:

> > If you're specifying the interpreter in your command (by calling
> > "python <scriptname>.py", etc), the shebang won't mean anything
> > anyway.

> DOH!  

> I was following you, fine, until that last sentence.  Then how should
> I invoke the scripts? ....as your example is exactly how I've been
> doing it with 2.7, as per Learn Python the Hard Way.  Simply
> ./<scriptname>.py from the appropriate directory (assuming I keep both
> vers in separate dirs)?

There are two ways (at least!) to run a python script:

1. Execute the python interpreter manually, supplying the python script name
   as an arugment, like so:

     python myscript.py
     python2 otherscript.py
     python3 yetanotherscript.py

This lets you choose on-the-fly which version of python is being used to
interpret the script.

2. Execute the python script directly by just typing its name, like so:

     myscript.py
     ./otherscript.py
     /other/directory/yetanotherscript.py

   Depending on your operating system, this may require:
     a. Permissions on the script file be set to allow execution; 
     b. A 'shebang' entry as the first line in the file which specifies the
        program that shall be executed;

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon at panix.com    watch 'House', or a real serial killer to watch 'Dexter'.



From eric.jacoboni at gmail.com  Thu Mar 20 15:07:25 2014
From: eric.jacoboni at gmail.com (Eric Jacoboni)
Date: Thu, 20 Mar 2014 20:07:25 +0100
Subject: running python 2 vs 3
In-Reply-To: <87ob10nbeh.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
Message-ID: <lgfeb3$clj$1@cabale.usenet-fr.net>

Le 20/03/2014 16:21, Marko Rauhamaa a ?crit :


> All tutorials will tell you to start it with
> 
>    #!/usr/bin/env python
> 
> which will start python2 on all (?) existing linux distros, but is
> expected to start python3 within the next decade.

With Arch-Linux, python is python3...



From harrismh777 at gmail.com  Thu Mar 20 15:36:32 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 20 Mar 2014 14:36:32 -0500
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <lgf3ve$iuc$1@speranza.aioe.org> <bp0mgcF7aqdU4@mid.individual.net>
 <lgf99a$3fc$1@speranza.aioe.org> <87fvmcn4o1.fsf@elektro.pacujo.net>
Message-ID: <lgffvt$n40$1@speranza.aioe.org>

On 3/20/14 12:47 PM, Marko Rauhamaa wrote:
> I've seen it done, but at least in those Python 2 days the pyc format
> changed between minor releases of Python, so Python itself had to be
> shipped with the pyc files.

hi Marko, yeah, I have not done this; being that the concept is contrary 
to my principles and sensibilities these days. So,

   1) no intellectual property
   2) no software idea patents
   3) no obfuscated code
   4) ship the source, or don't ship anything/

In my view coding (and all other aspects of computer science including 
software engineering) is a liberal art; it should be open, free (libre), 
and available to everyone. People learn best by doing, and the do best 
by reading what others have done before them.

marcus


From ameyer2 at yahoo.com  Thu Mar 20 15:53:52 2014
From: ameyer2 at yahoo.com (Alan Meyer)
Date: Thu, 20 Mar 2014 15:53:52 -0400
Subject: running python 2 vs 3
In-Reply-To: <87ob10nbeh.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
Message-ID: <532B4750.2090006@yahoo.com>

On 3/20/2014 11:21 AM, Marko Rauhamaa wrote:

> On a linux box, the initial line of the script indicates the
> interpreter:
>
>     #!/usr/bin/env python2
>
> for Python 2.x
>
>     #!/usr/bin/env python3
>
> for Python 3.x.
>
> All tutorials will tell you to start it with
>
>     #!/usr/bin/env python
>
> which will start python2 on all (?) existing linux distros, but is
> expected to start python3 within the next decade.
>
>
> Marko

I presume it would still be a good idea to test both python interpreters 
against any script that you didn't knowingly write with a feature that 
will only work in one of the two python versions.

If it works fine in both - and many will, then use:

      #!/usr/bin/env python

Only use the "python2" or "python3" versions if you really have a reason 
to do so.

Yes?  No?

    Alan


From roy.snuffles at gmail.com  Thu Mar 20 15:55:33 2014
From: roy.snuffles at gmail.com (roy.snuffles at gmail.com)
Date: Thu, 20 Mar 2014 12:55:33 -0700 (PDT)
Subject: File Path/Global name issue
Message-ID: <2089d20b-aa60-462f-aad0-51109849cf36@googlegroups.com>

I am currently running code for a program called HotNet (https://github.com/raphael-group/hotnet)

In its simpleRun.py file, there is a place to insert a file path to be run. 

parser.add_argument('-mf', '--infmat_file', required=True,
                        help='Path to .mat file containing influence matrix')

My path file is /home/lai/Downloads/influence_matrix_files/hprd_inf_.mat

And I have tried to add it in as such: 

Input: 

parser.add_argument('-mf', '--infmat_file', required=True,
                   help= /home/lai/Downloads/influence_matrix_file/hprd_inf_.mat)

Output:   

File "simpleRun.py", line 29
    help= ~/home/lai/Downloads/influence_matrix_files/hprd_inf_.mat)
           ^
SyntaxError: invalid syntax

I have also tried to place the path in ' ' but that isn't processed.

I have tried removing the / however that just returns the following error: 

NameError: global name 'home' is not defined


Completely new at this, so thank you for bearing with me and for the help!



From skip at pobox.com  Thu Mar 20 16:05:41 2014
From: skip at pobox.com (Skip Montanaro)
Date: Thu, 20 Mar 2014 15:05:41 -0500
Subject: File Path/Global name issue
In-Reply-To: <2089d20b-aa60-462f-aad0-51109849cf36@googlegroups.com>
References: <2089d20b-aa60-462f-aad0-51109849cf36@googlegroups.com>
Message-ID: <CANc-5UyVRuhDh55a4Cb-T6ky031QJUV0wSDwX86mK4_TSOgytQ@mail.gmail.com>

On Thu, Mar 20, 2014 at 2:55 PM,  <roy.snuffles at gmail.com> wrote:
> File "simpleRun.py", line 29
>     help= ~/home/lai/Downloads/influence_matrix_files/hprd_inf_.mat)
>            ^
> SyntaxError: invalid syntax

You need quotes around the filename. It's a string literal.

Skip


From roy.snuffles at gmail.com  Thu Mar 20 16:08:06 2014
From: roy.snuffles at gmail.com (roy.snuffles at gmail.com)
Date: Thu, 20 Mar 2014 13:08:06 -0700 (PDT)
Subject: File Path/Global name issue
In-Reply-To: <mailman.8311.1395345950.18130.python-list@python.org>
References: <2089d20b-aa60-462f-aad0-51109849cf36@googlegroups.com>
 <mailman.8311.1395345950.18130.python-list@python.org>
Message-ID: <f890ea65-d47d-4b4c-ac12-fd479e42ee60@googlegroups.com>

Hi Skip! 
Thank you so much for the response. When I put quotes around the file name I receive this output. 

simpleRun.py: error: argument -mf/--infmat_file is required


From marko at pacujo.net  Thu Mar 20 16:08:37 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 20 Mar 2014 22:08:37 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
Message-ID: <87eh1wpr96.fsf@elektro.pacujo.net>

Alan Meyer <ameyer2 at yahoo.com>:

> I presume it would still be a good idea to test both python
> interpreters against any script that you didn't knowingly write with a
> feature that will only work in one of the two python versions.
>
> If it works fine in both - and many will, then use:
>
>      #!/usr/bin/env python
>
> Only use the "python2" or "python3" versions if you really have a
> reason to do so.
>
> Yes?  No?

No. Even if you managed to do that, it would mean getting the worst of
both worlds. The language dialects are too far apart. When you start
your Python project, you decide between Python 2 and Python 3 and go all
in.


Marko


From harrismh777 at gmail.com  Thu Mar 20 16:10:04 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 20 Mar 2014 15:10:04 -0500
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
Message-ID: <lgfhup$sth$1@speranza.aioe.org>

On 3/20/14 2:53 PM, Alan Meyer wrote:
> #!/usr/bin/env python
>
> Only use the "python2" or "python3" versions if you really have a reason
> to do so.

It gets tricky for distribution (you need docs for your distros, imho) 
because #!/usr/bin/env python  means different things on different 
systems.

I actually have three major versions of python2 and 2 major versions of 
python3 on my primary system at this point. On my machine python2.6 is 
"python".  That is because that system shipped with 2.6 and many of the 
subsystem stuff depends on python2.6 /

When I call python2 that means python2.7.6 /

When I call python3 that means python3.3.4 /

I can also call python2.7, which is 2.7.2 /

You get the idea.   There is no one set rule, because there are many 
distros (gnu/linux) that use python at various versions, and they all us 
different setups.  Really , you need an install script to snoop out the 
configurables.

marcus


From skip at pobox.com  Thu Mar 20 16:15:42 2014
From: skip at pobox.com (Skip Montanaro)
Date: Thu, 20 Mar 2014 15:15:42 -0500
Subject: File Path/Global name issue
In-Reply-To: <f890ea65-d47d-4b4c-ac12-fd479e42ee60@googlegroups.com>
References: <2089d20b-aa60-462f-aad0-51109849cf36@googlegroups.com>
 <mailman.8311.1395345950.18130.python-list@python.org>
 <f890ea65-d47d-4b4c-ac12-fd479e42ee60@googlegroups.com>
Message-ID: <CANc-5UxVUy_oCCowYo0JxPOL+7XBsJVVLQyhoJceN-ppxjBOoQ@mail.gmail.com>

On Thu, Mar 20, 2014 at 3:08 PM,  <roy.snuffles at gmail.com> wrote:
> simpleRun.py: error: argument -mf/--infmat_file is required

I think you are misinterpreting the actual purpose of the
parser_add_argument() call. It's telling you that *on the command
line* you can specify it using either

-mf some-file-name

or

--infmat_file=some-file-name

It also tells you that it is a required argument.

I don't believe you are supposed to have to modify the source to run
the program. I'd set the argument to the "help=..." parameter back to
however it was set when you got it and try either of the above command
line args.

Skip


From breamoreboy at yahoo.co.uk  Thu Mar 20 16:22:33 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 20 Mar 2014 20:22:33 +0000
Subject: running python 2 vs 3
In-Reply-To: <87eh1wpr96.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
Message-ID: <lgfilv$abl$1@ger.gmane.org>

On 20/03/2014 20:08, Marko Rauhamaa wrote:
> Alan Meyer <ameyer2 at yahoo.com>:
>
>> I presume it would still be a good idea to test both python
>> interpreters against any script that you didn't knowingly write with a
>> feature that will only work in one of the two python versions.
>>
>> If it works fine in both - and many will, then use:
>>
>>       #!/usr/bin/env python
>>
>> Only use the "python2" or "python3" versions if you really have a
>> reason to do so.
>>
>> Yes?  No?
>
> No. Even if you managed to do that, it would mean getting the worst of
> both worlds. The language dialects are too far apart. When you start
> your Python project, you decide between Python 2 and Python 3 and go all
> in.
>
> Marko
>

I do not agree that the dialects are too far apart, not that it really 
matters.  There are several libraries available to enable code to run 
under both versions.  The starter is 2to3 which had been in the standard 
library for what seems like an eternity to me.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From __peter__ at web.de  Thu Mar 20 16:26:21 2014
From: __peter__ at web.de (Peter Otten)
Date: Thu, 20 Mar 2014 21:26:21 +0100
Subject: File Path/Global name issue
References: <2089d20b-aa60-462f-aad0-51109849cf36@googlegroups.com>
Message-ID: <lgfisv$859$1@ger.gmane.org>

roy.snuffles at gmail.com wrote:

> I am currently running code for a program called HotNet
> (https://github.com/raphael-group/hotnet)
> 
> In its simpleRun.py file, there is a place to insert a file path to be
> run.
> 
> parser.add_argument('-mf', '--infmat_file', required=True,
>                         help='Path to .mat file containing influence
>                         matrix')
> 
> My path file is /home/lai/Downloads/influence_matrix_files/hprd_inf_.mat
> 
> And I have tried to add it in as such:
> 
> Input:
> 
> parser.add_argument('-mf', '--infmat_file', required=True,
>                    help=
>                    /home/lai/Downloads/influence_matrix_file/hprd_inf_.mat)
> 
> Output:
> 
> File "simpleRun.py", line 29
>     help= ~/home/lai/Downloads/influence_matrix_files/hprd_inf_.mat)
>            ^
> SyntaxError: invalid syntax
> 
> I have also tried to place the path in ' ' but that isn't processed.
> 
> I have tried removing the / however that just returns the following error:
> 
> NameError: global name 'home' is not defined
> 
> 
> Completely new at this, so thank you for bearing with me and for the help!

Reread the documentation, you are misunderstanding it. You don't have to 
modify the simpleRun.py script, you should invoke it from the commandline 
with the file as one of its arguments:

$ python simpleRun.py --infmat_file /home/lai/Downloads/influence_matrix_files/hprd_inf_.mat

As there are more required arguments you will end up with a very long 
command line. But there is an alternative. Create a config file like the 
following

https://github.com/raphael-group/hotnet/blob/master/example/configs/simple.config

where you replace all the file names with those of your actual files and 
then invoke simpleRun.py with

$ python simpleRun.py @roy_snuffles.config




From ned at nedbatchelder.com  Thu Mar 20 16:26:39 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Thu, 20 Mar 2014 16:26:39 -0400
Subject: running python 2 vs 3
In-Reply-To: <lgfeb3$clj$1@cabale.usenet-fr.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <lgfeb3$clj$1@cabale.usenet-fr.net>
Message-ID: <lgfitg$cpv$1@ger.gmane.org>

On 3/20/14 3:07 PM, Eric Jacoboni wrote:
> Le 20/03/2014 16:21, Marko Rauhamaa a ?crit :
>
>
>> All tutorials will tell you to start it with
>>
>>     #!/usr/bin/env python
>>
>> which will start python2 on all (?) existing linux distros, but is
>> expected to start python3 within the next decade.
>
> With Arch-Linux, python is python3...
>

Yes, and they have been told many times that this was foolish and wrong, 
but it persists, much to our pain.

-- 
Ned Batchelder, http://nedbatchelder.com



From ned at nedbatchelder.com  Thu Mar 20 16:27:59 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Thu, 20 Mar 2014 16:27:59 -0400
Subject: running python 2 vs 3
In-Reply-To: <87eh1wpr96.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
Message-ID: <lgfj00$cpv$2@ger.gmane.org>

On 3/20/14 4:08 PM, Marko Rauhamaa wrote:
> Alan Meyer <ameyer2 at yahoo.com>:
>
>> I presume it would still be a good idea to test both python
>> interpreters against any script that you didn't knowingly write with a
>> feature that will only work in one of the two python versions.
>>
>> If it works fine in both - and many will, then use:
>>
>>       #!/usr/bin/env python
>>
>> Only use the "python2" or "python3" versions if you really have a
>> reason to do so.
>>
>> Yes?  No?
>
> No. Even if you managed to do that, it would mean getting the worst of
> both worlds. The language dialects are too far apart. When you start
> your Python project, you decide between Python 2 and Python 3 and go all
> in.

Plenty of people have adopted a dual-support strategy, with one code 
base that supports both Python 2 and Python 3.  The six module can help 
a great deal with this.

>
>
> Marko
>


-- 
Ned Batchelder, http://nedbatchelder.com



From marko at pacujo.net  Thu Mar 20 16:30:57 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 20 Mar 2014 22:30:57 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
Message-ID: <87a9ckpq7y.fsf@elektro.pacujo.net>

Mark Lawrence <breamoreboy at yahoo.co.uk>:

> The starter is 2to3 which had been in the standard library for what
> seems like an eternity to me.

No problem there. It helps you transition from python2 to python3.

However, python3 is here and you should be able to write genuine python3
code with the appropriate bytes and string facilities. It would be very
confusing to try to mix the two regimes.

I must say, though, that Python3 destroyed "print" forever for me. To
avoid nausea, I write sys.stdout.write() in all Python3 code.


Marko


From drsalists at gmail.com  Thu Mar 20 16:38:10 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Thu, 20 Mar 2014 13:38:10 -0700
Subject: running python 2 vs 3
In-Reply-To: <87ob10nbeh.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
Message-ID: <CAGGBd_q=2H0Yh=35cFOWuMca9r6ARtyYcoEyCj36PO778z+Dsg@mail.gmail.com>

On Thu, Mar 20, 2014 at 8:21 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> notbob <notbob at nothome.com>:
>
>> I've installed python 3.3 on my Slack box, which by default comes with
>> python 2.7. I know how to fire up the different IDLE environments, but
>> how do I differentiate between the scripts? IOW, up till now, I've
>> used .py on all my 2.7 files. How do I know not to run a .py in
>> python3 or visa versa? Or do I? What's the excepted convention for
>> differentiating between the two?
>
> That's a bit of a sore spot.
>
> On a linux box, the initial line of the script indicates the
> interpreter:
>
>    #!/usr/bin/env python2
>
> for Python 2.x
>
>    #!/usr/bin/env python3
>
> for Python 3.x.
>
> All tutorials will tell you to start it with
>
>    #!/usr/bin/env python

Actually, I formerly used /usr/bin/env, but have recently (within the
last couple of years) stopped.

This is because the env trick doesn't play nicely with top IME.  Also,
it's a trick.


From zachary.ware+pylist at gmail.com  Thu Mar 20 16:43:50 2014
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Thu, 20 Mar 2014 15:43:50 -0500
Subject: running python 2 vs 3
In-Reply-To: <87a9ckpq7y.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
 <532B4750.2090006@yahoo.com> <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
Message-ID: <CAKJDb-O=39UGJfDrXQQfEu_o6UeOx6nggM+EXdG+O-hqwxLVMw@mail.gmail.com>

On Thu, Mar 20, 2014 at 3:30 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> I must say, though, that Python3 destroyed "print" forever for me. To
> avoid nausea, I write sys.stdout.write() in all Python3 code.

To each their own :).  I can't stand using 'print' as a statement.
It's a very nice trick to be able to write a script, think "oh, all
those prints should really be sending that output somewhere else", and
then instead of changing every individual print, just define a
different 'print' function at the top of the file (which may be as
simple as `print = functools.partial(print, file=sys.stderr)` or
`print = logging.debug`).

-- 
Zach


From breamoreboy at yahoo.co.uk  Thu Mar 20 16:44:03 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 20 Mar 2014 20:44:03 +0000
Subject: running python 2 vs 3
In-Reply-To: <87a9ckpq7y.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
Message-ID: <lgfju9$qeu$1@ger.gmane.org>

On 20/03/2014 20:30, Marko Rauhamaa wrote:
> Mark Lawrence <breamoreboy at yahoo.co.uk>:
>
>> The starter is 2to3 which had been in the standard library for what
>> seems like an eternity to me.
>
> No problem there. It helps you transition from python2 to python3.
>
> However, python3 is here and you should be able to write genuine python3
> code with the appropriate bytes and string facilities. It would be very
> confusing to try to mix the two regimes.
>
> I must say, though, that Python3 destroyed "print" forever for me. To
> avoid nausea, I write sys.stdout.write() in all Python3 code.
>

Not for me, I was using from __future__ import print_function for years 
so got used to typing those two extra brackets, plus print very kindly 
inserts the newlines for me.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From marko at pacujo.net  Thu Mar 20 16:42:41 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 20 Mar 2014 22:42:41 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
Message-ID: <8738icppoe.fsf@elektro.pacujo.net>

Ned Batchelder <ned at nedbatchelder.com>:

> Plenty of people have adopted a dual-support strategy, with one code
> base that supports both Python 2 and Python 3. The six module can help
> a great deal with this.

I wonder how easy the resulting code is to the eyes and how easy it is
for the casual maintainer to accidentally break the delicate balance. In
a word, I wouldn't go there. Stay with Python2 as long as you must and
then, migrate and leave it behind.


Marko


From marko at pacujo.net  Thu Mar 20 16:46:09 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 20 Mar 2014 22:46:09 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
 <mailman.8317.1395347899.18130.python-list@python.org>
Message-ID: <87y504oay6.fsf@elektro.pacujo.net>

Dan Stromberg <drsalists at gmail.com>:

> Actually, I formerly used /usr/bin/env, but have recently (within the
> last couple of years) stopped.
>
> This is because the env trick doesn't play nicely with top IME. Also,
> it's a trick.

I'm not sure I like it either, but it's a standard idiom in Pythonland.


Marko


From ned at nedbatchelder.com  Thu Mar 20 16:53:25 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Thu, 20 Mar 2014 16:53:25 -0400
Subject: running python 2 vs 3
In-Reply-To: <8738icppoe.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
Message-ID: <lgfkfl$2tt$1@ger.gmane.org>

On 3/20/14 4:42 PM, Marko Rauhamaa wrote:
> Ned Batchelder <ned at nedbatchelder.com>:
>
>> Plenty of people have adopted a dual-support strategy, with one code
>> base that supports both Python 2 and Python 3. The six module can help
>> a great deal with this.
>
> I wonder how easy the resulting code is to the eyes and how easy it is
> for the casual maintainer to accidentally break the delicate balance. In
> a word, I wouldn't go there. Stay with Python2 as long as you must and
> then, migrate and leave it behind.

This is fine advice for applications, but tools, libraries, and 
frameworks may want to support more than one version at the same time.

It's an extreme case, but the latest released version of coverage.py 
supports Python 2.3 through 3.3 with one code base.  To do it, there's a 
compatibility layer (akin to six).  Then you stay away from features 
that aren't available on all versions.  In a few places, you might need 
to have version checks, and the code can get a little idiomatic to 
continue to work.

It's a tradeoff: you have to decide for yourself whether the effort is 
worth the benefit.  I was glad to be able to drop support for 2.3, 2.4, 
and 2.5, and now only support 2.6-3.4 in coverage.py.

>
>
> Marko
>


-- 
Ned Batchelder, http://nedbatchelder.com



From marko at pacujo.net  Thu Mar 20 16:50:45 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 20 Mar 2014 22:50:45 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
 <mailman.8319.1395348268.18130.python-list@python.org>
Message-ID: <87txasoaqi.fsf@elektro.pacujo.net>

Mark Lawrence <breamoreboy at yahoo.co.uk>:

> On 20/03/2014 20:30, Marko Rauhamaa wrote:
>> I must say, though, that Python3 destroyed "print" forever for me. To
>> avoid nausea, I write sys.stdout.write() in all Python3 code.
>
> Not for me, I was using from __future__ import print_function for
> years so got used to typing those two extra brackets, plus print very
> kindly inserts the newlines for me.

That very realization helped me wean myself from "print." Its sole
raison d'?tre is the insertion of the newline, which it would be nicer
to micromanage anyway; that's how it's done in other programming
languages as well: C, perl, guile, ... (Well, ok, "echo" is the
exception.)


Marko


From marko at pacujo.net  Thu Mar 20 16:59:21 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 20 Mar 2014 22:59:21 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
Message-ID: <87pplgoac6.fsf@elektro.pacujo.net>

Ned Batchelder <ned at nedbatchelder.com>:

> It's an extreme case, but the latest released version of coverage.py
> supports Python 2.3 through 3.3 with one code base. To do it, there's
> a compatibility layer (akin to six). Then you stay away from features
> that aren't available on all versions. In a few places, you might need
> to have version checks, and the code can get a little idiomatic to
> continue to work.

Well, with proper care, I suppose the same code base could support perl
as well. ;)


Marko


From ckaynor at zindagigames.com  Thu Mar 20 17:18:41 2014
From: ckaynor at zindagigames.com (Chris Kaynor)
Date: Thu, 20 Mar 2014 14:18:41 -0700
Subject: running python 2 vs 3
In-Reply-To: <87pplgoac6.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
 <532B4750.2090006@yahoo.com> <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
 <87pplgoac6.fsf@elektro.pacujo.net>
Message-ID: <CALvWhxuXuU_dM4tA5sSiE2MtPQ+Yxp_Q7wd8tNV0Y4D7hKo0uw@mail.gmail.com>

On Thu, Mar 20, 2014 at 1:59 PM, Marko Rauhamaa <marko at pacujo.net> wrote:

> Well, with proper care, I suppose the same code base could support perl
> as well. ;)
>

Go even farther; how about C, PHP, and bash? I'm sure if you tried, you
could mix in some Python as well.
http://en.wikipedia.org/wiki/Polyglot_(computing)

Chris
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From notbob at nothome.com  Thu Mar 20 17:16:36 2014
From: notbob at nothome.com (notbob)
Date: 20 Mar 2014 21:16:36 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <lgfeb3$clj$1@cabale.usenet-fr.net>
 <mailman.8315.1395347215.18130.python-list@python.org>
Message-ID: <bp145kFaoq9U1@mid.individual.net>

On 2014-03-20, Ned Batchelder <ned at nedbatchelder.com> wrote:

> On 3/20/14 3:07 PM, Eric Jacoboni wrote:

>> With Arch-Linux, python is python3...
>>

> Yes, and they have been told many times that this was foolish and wrong, 
> but it persists, much to our pain.

I've read that 2.7 is the defacto std for python (default on Slack
14.1).  I installed py3 on Slack box cuz I'd gotten the little
"Programming the Raspberry Pi" book, which is a pretty good lil' book,
clarifying many confusing (to me) python issues.  Only prob is, it's
fer python 3x.  I guess I coulda kept the two platforms separate, but
then raspi has 2X and 3x, also, so I guess I need to get this issue
straight in my feeble geezer head, right outta the gate.  I'm plum
grateful to all you kind folks who are taking the time to educate this
slow ol' curmudgeon.  ;)

nb    


From notbob at nothome.com  Thu Mar 20 17:28:43 2014
From: notbob at nothome.com (notbob)
Date: 20 Mar 2014 21:28:43 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <lgfhup$sth$1@speranza.aioe.org>
Message-ID: <bp14sbFaoq9U2@mid.individual.net>

On 2014-03-20, Mark H Harris <harrismh777 at gmail.com> wrote:

> When I call python2 that means python2.7.6 /
>
> When I call python3 that means python3.3.4 /
>
> I can also call python2.7, which is 2.7.2 /
>
> You get the idea.   There is no one set rule, because there are many 
> distros (gnu/linux) that use python at various versions, and they all us 
> different setups.  Really , you need an install script to snoop out the 
> configurables.

Weeping Chryst on the cross!!.  No wonder the latest O'Reilly book,
Learning Python, 5th ed, is 1600 pgs.  I coulda swore someone sed
python is easy.  ;)

nb   


From ned at nedbatchelder.com  Thu Mar 20 17:31:58 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Thu, 20 Mar 2014 17:31:58 -0400
Subject: running python 2 vs 3
In-Reply-To: <87pplgoac6.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
 <87pplgoac6.fsf@elektro.pacujo.net>
Message-ID: <lgfmnv$tjt$1@ger.gmane.org>

On 3/20/14 4:59 PM, Marko Rauhamaa wrote:
> Ned Batchelder <ned at nedbatchelder.com>:
>
>> It's an extreme case, but the latest released version of coverage.py
>> supports Python 2.3 through 3.3 with one code base. To do it, there's
>> a compatibility layer (akin to six). Then you stay away from features
>> that aren't available on all versions. In a few places, you might need
>> to have version checks, and the code can get a little idiomatic to
>> continue to work.
>
> Well, with proper care, I suppose the same code base could support perl
> as well. ;)

I'm not sure how to take this comment.  I feel like you are mocking my 
choice.  I wanted to make coverage.py available to as broad an audience 
as possible, something that I think is worthwhile.  Yes, there was an 
engineering cost, but the tradeoff was worth it.

>
>
> Marko
>


-- 
Ned Batchelder, http://nedbatchelder.com



From gordon at panix.com  Thu Mar 20 17:31:15 2014
From: gordon at panix.com (John Gordon)
Date: Thu, 20 Mar 2014 21:31:15 +0000 (UTC)
Subject: File Path/Global name issue
References: <2089d20b-aa60-462f-aad0-51109849cf36@googlegroups.com>
Message-ID: <lgfmn3$rua$1@reader1.panix.com>

In <2089d20b-aa60-462f-aad0-51109849cf36 at googlegroups.com> roy.snuffles at gmail.com writes:

> I am currently running code for a program called HotNet (https://github.com/raphael-group/hotnet)

> In its simpleRun.py file, there is a place to insert a file path to be run. 

> parser.add_argument('-mf', '--infmat_file', required=True,
>                         help='Path to .mat file containing influence matrix')

> My path file is /home/lai/Downloads/influence_matrix_files/hprd_inf_.mat

You're completely misunderstanding the purpose of this line of code.  Its
intent is to allow you to pass the matrix file location to the script by
using the '-mf' or '--infmat_file' arguments, thus not requiring you to
edit the script at all.

The 'help' parameter provides a message explaining the usage of that
particular argument if the simpleRun.py script is executed with the '-help'
option.

For example, if you were unsure how to use the simpleRun.py script, you
might run this command:

    simpleRun.py -help

And you might see output that looks like this:

    Usage: simpleRun.py [options]

    Options:
      -h, --help            show this help message and exit
      -mf, --infmat_file    Path to .mat file containing influence matrix
      -d, --dance           do a little dance
      -l, --love            make a little love

The help message thus informs you that you can provide the location to an
influence matrix file by using the '-mf' or '--infmat_file' arguments.
There are also -d and -l options that do ... something.

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon at panix.com    watch 'House', or a real serial killer to watch 'Dexter'.



From breamoreboy at yahoo.co.uk  Thu Mar 20 17:36:38 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 20 Mar 2014 21:36:38 +0000
Subject: running python 2 vs 3
In-Reply-To: <87txasoaqi.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
 <mailman.8319.1395348268.18130.python-list@python.org>
 <87txasoaqi.fsf@elektro.pacujo.net>
Message-ID: <lgfn0s$129$1@ger.gmane.org>

On 20/03/2014 20:50, Marko Rauhamaa wrote:
> Mark Lawrence <breamoreboy at yahoo.co.uk>:
>
>> On 20/03/2014 20:30, Marko Rauhamaa wrote:
>>> I must say, though, that Python3 destroyed "print" forever for me. To
>>> avoid nausea, I write sys.stdout.write() in all Python3 code.
>>
>> Not for me, I was using from __future__ import print_function for
>> years so got used to typing those two extra brackets, plus print very
>> kindly inserts the newlines for me.
>
> That very realization helped me wean myself from "print." Its sole
> raison d'?tre is the insertion of the newline, which it would be nicer
> to micromanage anyway; that's how it's done in other programming
> languages as well: C, perl, guile, ... (Well, ok, "echo" is the
> exception.)
>
>
> Marko
>

The end keyword argument to the print function defaults to newline but 
you can make it anything you like, see 
http://docs.python.org/3/library/functions.html#print

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From harrismh777 at gmail.com  Thu Mar 20 17:46:35 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 20 Mar 2014 16:46:35 -0500
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <lgfhup$sth$1@speranza.aioe.org> <bp14sbFaoq9U2@mid.individual.net>
Message-ID: <lgfnjn$fd9$1@speranza.aioe.org>

On 3/20/14 4:28 PM, notbob wrote:
> No wonder the latest O'Reilly book, Learning Python, 5th ed,
is 1600 pgs.  I coulda swore someone sed python is easy.  ;)
> nb

Python is easy, but its not simple.
Python is elegant, and full of art, but it has no paucity of constructs, 
types, and opportunities for confusion.

My goal for designing SimplyPy (for instance)is to present the beautiful 
heart of python (as Mark Summerfield calls it) and subsume the 
complexities of the fulness of python within a simple interface, BUT 
without limiting it.

Python is easy enough to teach children (I've done it), but its 
"complete and elegant enough" for the most scientific of professionals.

You do not need to know the fulness of python in order to use it. It is 
possible (even elegant) to use python (in a Rexx style) not at all 
recognized as "pythonized" code, and yet very very simple and powerful.

The beauty of python, in my view, is the flexibility and extensibility 
of the namespace with something more than the minimalist approach of 
Lisp, BUT with the elegance of the language called python.

Get Mark Summerfield's Programming Python 3.  Its really quite good, and 
in my opinion better that the O'Reilly book, especially for new users.

Just an opinion of course.

marcus



From tjreedy at udel.edu  Thu Mar 20 17:52:02 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 20 Mar 2014 17:52:02 -0400
Subject: running python 2 vs 3
In-Reply-To: <bp0mgcF7aqdU4@mid.individual.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <lgf3ve$iuc$1@speranza.aioe.org> <bp0mgcF7aqdU4@mid.individual.net>
Message-ID: <lgfntp$c3o$1@ger.gmane.org>

On 3/20/2014 1:23 PM, notbob wrote:

> What the heck is a .pyc file and how are they created?

.pyc contained compiled bytecode. They are created when, and only when, 
you import a module.  Imported library files are often big and stable, 
so their compiled forms get cached. Top-level scripts are typically 
short and often volotile. They may be as short as "from start import 
run; run()" in order to have as much as possible stored in compiled form.

This has nothing to do with Idle.

> I went back to my ~/python/ dir and noticed one .pyc file out of 15
> .py files I created from following Learning Python the Hard Way.

That must be the only one you imported.

-- 
Terry Jan Reedy



From tjreedy at udel.edu  Thu Mar 20 18:05:49 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 20 Mar 2014 18:05:49 -0400
Subject: running python 2 vs 3
In-Reply-To: <lgfe9q$9hv$1@reader1.panix.com>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <bp0hk7F613oU3@mid.individual.net>
 <mailman.8304.1395332703.18130.python-list@python.org>
 <bp0lohF7aqdU3@mid.individual.net> <lgfe9q$9hv$1@reader1.panix.com>
Message-ID: <lgfonk$kth$1@ger.gmane.org>

On 3/20/2014 3:07 PM, John Gordon wrote:

> There are two ways (at least!) to run a python script:
>
> 1. Execute the python interpreter manually, supplying the python script name
>     as an arugment, like so:
>
>       python myscript.py
>       python2 otherscript.py
>       python3 yetanotherscript.py
>
> This lets you choose on-the-fly which version of python is being used to
> interpret the script.
>
> 2. Execute the python script directly by just typing its name, like so:
>
>       myscript.py
>       ./otherscript.py
>       /other/directory/yetanotherscript.py
>
>     Depending on your operating system, this may require:
>       a. Permissions on the script file be set to allow execution;
>       b. A 'shebang' entry as the first line in the file which specifies the
>          program that shall be executed;

         c. An association between '.py' and some version of python.

3. Use the python launcher py.exe with version selection.
     py -2 myscript.py
     py -3 myscript.py

As far as I know, this is only for Windows at present.

-- 
Terry Jan Reedy



From torriem at gmail.com  Thu Mar 20 17:44:27 2014
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 20 Mar 2014 15:44:27 -0600
Subject: running python 2 vs 3
In-Reply-To: <bp0lohF7aqdU3@mid.individual.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <bp0hk7F613oU3@mid.individual.net>
 <mailman.8304.1395332703.18130.python-list@python.org>
 <bp0lohF7aqdU3@mid.individual.net>
Message-ID: <532B613B.4030901@gmail.com>

On 03/20/2014 11:10 AM, notbob wrote:
> On 2014-03-20, Zachary Ware <zachary.ware+pylist at gmail.com> wrote:
> 
>> If you're specifying the interpreter in your command (by calling
>> "python <scriptname>.py", etc), the shebang won't mean anything
>> anyway.
> 
> DOH!  
> 
> I was following you, fine, until that last sentence.  Then how should
> I invoke the scripts? ....as your example is exactly how I've been
> doing it with 2.7, as per Learn Python the Hard Way.  Simply
> ./<scriptname>.py from the appropriate directory (assuming I keep both
> vers in separate dirs)?'

If you want to run a script with python3, just invoke the python3
interpreter:

python3 blah.py



From marko at pacujo.net  Thu Mar 20 18:17:07 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 21 Mar 2014 00:17:07 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <lgfhup$sth$1@speranza.aioe.org> <bp14sbFaoq9U2@mid.individual.net>
Message-ID: <877g7oms64.fsf@elektro.pacujo.net>

notbob <notbob at nothome.com>:

> Weeping Chryst on the cross!!. No wonder the latest O'Reilly book,
> Learning Python, 5th ed, is 1600 pgs. I coulda swore someone sed
> python is easy. ;)

It's not that bad. There are two principal dialects: python2 and
python3. Take the oldest python version you have to support and write
your code for that version.

Python documentation carefully explains what language and library
facilities are available in whichever version.


Marko


From notbob at nothome.com  Thu Mar 20 18:19:30 2014
From: notbob at nothome.com (notbob)
Date: 20 Mar 2014 22:19:30 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <lgf3ve$iuc$1@speranza.aioe.org> <bp0mgcF7aqdU4@mid.individual.net>
 <mailman.8324.1395352349.18130.python-list@python.org>
Message-ID: <bp17riFaoq9U5@mid.individual.net>

On 2014-03-20, Terry Reedy <tjreedy at udel.edu> wrote:

> That must be the only one you imported.

So it is.  Thank you.

nb


From greg.ewing at canterbury.ac.nz  Thu Mar 20 18:19:50 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Fri, 21 Mar 2014 11:19:50 +1300
Subject: Question about Source Control
In-Reply-To: <mailman.8290.1395299735.18130.python-list@python.org>
References: <lg6s09$irl$1@ger.gmane.org> <lgbe6g$j9o$1@ger.gmane.org>
 <lge2v9$h0l$1@ger.gmane.org>
 <mailman.8290.1395299735.18130.python-list@python.org>
Message-ID: <bp17s6Fbs18U1@mid.individual.net>

Chris Angelico wrote:
> You can then offer a non-source-control means of downloading that
> specific revision.

Just keep in mind the downside that you can't then
push or pull your changes directly back into the main
repository. You can generate a patch file for the
project maintainer to apply, however. Hg makes it
very easy to produce a patch file between any two
revisions.

Also, unless the project is truly ancient, the
whole history might not be as big as you expect.
The code presumably grew to its present size
incrementally, in an approximately monotonic
manner, so the sum of all the diffs is probably
about the same order of magnitude as the current
code size.

As an experiment, I just cloned a copy of the
CPython repository, and it's about 300MB. A
tarball of Python 3.2 that I downloaded and
compiled earlier is about 75MB. That's a ratio
of about 4, and CPython is a pretty ancient
project!

-- 
Greg


From marko at pacujo.net  Thu Mar 20 18:23:07 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 21 Mar 2014 00:23:07 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
 <87pplgoac6.fsf@elektro.pacujo.net>
 <mailman.8322.1395351136.18130.python-list@python.org>
Message-ID: <8738icmrw4.fsf@elektro.pacujo.net>

Ned Batchelder <ned at nedbatchelder.com>:
> On 3/20/14 4:59 PM, Marko Rauhamaa wrote:
>> Well, with proper care, I suppose the same code base could support perl
>> as well. ;)
>
> I'm not sure how to take this comment. I feel like you are mocking my
> choice. I wanted to make coverage.py available to as broad an audience
> as possible, something that I think is worthwhile. Yes, there was an
> engineering cost, but the tradeoff was worth it.

I can't judge if your particular choice was the right one. My only point
is that python2 and python3 are so far apart as to be regarded as
independent languages.


Marko


From rosuav at gmail.com  Thu Mar 20 18:34:23 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 09:34:23 +1100
Subject: Question about Source Control
In-Reply-To: <bp17s6Fbs18U1@mid.individual.net>
References: <lg6s09$irl$1@ger.gmane.org> <lgbe6g$j9o$1@ger.gmane.org>
 <lge2v9$h0l$1@ger.gmane.org>
 <mailman.8290.1395299735.18130.python-list@python.org>
 <bp17s6Fbs18U1@mid.individual.net>
Message-ID: <CAPTjJmq4MkGjOY_en-v=hA=3oJ1sef_uF8BbQ9nm6r8nPMwTgA@mail.gmail.com>

On Fri, Mar 21, 2014 at 9:19 AM, Gregory Ewing
<greg.ewing at canterbury.ac.nz> wrote:
> Chris Angelico wrote:
>>
>> You can then offer a non-source-control means of downloading that
>> specific revision.
>
> Just keep in mind the downside that you can't then
> push or pull your changes directly back into the main
> repository. You can generate a patch file for the
> project maintainer to apply, however. Hg makes it
> very easy to produce a patch file between any two
> revisions.

Yes, but a lot of people just want to get the software, they don't
actually need to generate patch files :)

> Also, unless the project is truly ancient, the
> whole history might not be as big as you expect.
> The code presumably grew to its present size
> incrementally, in an approximately monotonic
> manner, so the sum of all the diffs is probably
> about the same order of magnitude as the current
> code size.
>
> As an experiment, I just cloned a copy of the
> CPython repository, and it's about 300MB. A
> tarball of Python 3.2 that I downloaded and
> compiled earlier is about 75MB. That's a ratio
> of about 4, and CPython is a pretty ancient
> project!

Yep! But cloning requires that you have Mercurial installed and, more
importantly, know how to use it. We don't have a huge proliferation of
source control systems these days, but if someone says "Our code is
available via Perforce", I'm going to just look for a tarball
download, rather than figure out a source control system I don't know.

ChrisA


From steve+comp.lang.python at pearwood.info  Thu Mar 20 18:39:40 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 20 Mar 2014 22:39:40 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
Message-ID: <532b6e2c$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 20 Mar 2014 22:30:57 +0200, Marko Rauhamaa wrote:

> To avoid nausea, I write sys.stdout.write() in all Python3 code.

Now that's funny.


I-know-I-shouldn't-respond-to-obvious-trolling-but-I-can't-help-myself-ly 
yrs,

-- 
Steven D'Aprano


From breamoreboy at yahoo.co.uk  Thu Mar 20 18:42:39 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 20 Mar 2014 22:42:39 +0000
Subject: running python 2 vs 3
In-Reply-To: <8738icmrw4.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
 <87pplgoac6.fsf@elektro.pacujo.net>
 <mailman.8322.1395351136.18130.python-list@python.org>
 <8738icmrw4.fsf@elektro.pacujo.net>
Message-ID: <lgfqsk$c2c$1@ger.gmane.org>

On 20/03/2014 22:23, Marko Rauhamaa wrote:
> Ned Batchelder <ned at nedbatchelder.com>:
>> On 3/20/14 4:59 PM, Marko Rauhamaa wrote:
>>> Well, with proper care, I suppose the same code base could support perl
>>> as well. ;)
>>
>> I'm not sure how to take this comment. I feel like you are mocking my
>> choice. I wanted to make coverage.py available to as broad an audience
>> as possible, something that I think is worthwhile. Yes, there was an
>> engineering cost, but the tradeoff was worth it.
>
> I can't judge if your particular choice was the right one. My only point
> is that python2 and python3 are so far apart as to be regarded as
> independent languages.
>

And I still say this is complete nonsense.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Thu Mar 20 19:04:58 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 10:04:58 +1100
Subject: running python 2 vs 3
In-Reply-To: <87eh1wpr96.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpo4A8p7hNbssaoan3SaniQ4zBGEjuK0cYev-r2PD_few@mail.gmail.com>

On Fri, Mar 21, 2014 at 7:08 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Alan Meyer <ameyer2 at yahoo.com>:
>
>> I presume it would still be a good idea to test both python
>> interpreters against any script that you didn't knowingly write with a
>> feature that will only work in one of the two python versions.
>>
>> If it works fine in both - and many will, then use:
>>
>>      #!/usr/bin/env python
>>
>> Only use the "python2" or "python3" versions if you really have a
>> reason to do so.
>>
>> Yes?  No?
>
> No. Even if you managed to do that, it would mean getting the worst of
> both worlds. The language dialects are too far apart. When you start
> your Python project, you decide between Python 2 and Python 3 and go all
> in.

They're not that far apart. It's not difficult to write code that runs
happily on both. However, it does mean you can't take advantage of
Python 3 features, so it's probably better to write for one or the
other, unless you specifically want wide distribution. For your own
projects, just put whichever you need.

ChrisA


From fiensproto at gmail.com  Thu Mar 20 19:16:22 2014
From: fiensproto at gmail.com (fiensproto at gmail.com)
Date: Thu, 20 Mar 2014 16:16:22 -0700 (PDT)
Subject: CallBack function in C Libraries.
Message-ID: <a9908cb7-3566-42a8-a468-8179ac1df7ab@googlegroups.com>

Hello. I want to use a c library. It is a complete graphic widget set.

Here code working. But i have problem with the callback function. The callback is executed while ClikOnForm is executed but i get a error message (see after code )
____________________________________________________________________

file fpgui-test.py

from ctypes import*

def TheProc(c_int): fpgui.fpgFormWindowTitle(0, 'Boum')
return 0

CMPFUNC = CFUNCTYPE(c_int)

TheProcF = CMPFUNC(TheProc)

fpgui = cdll.LoadLibrary("fpgui-32.dll")

fpgui.fpgInitialize() fpgui.fpgSetStyle('Demo Style') fpgui.fpgFormCreate(0, -1) fpgui.fpgFormSetPosition(0, 300,100,400,200) fpgui.fpgFormWindowTitle(0, 'Hello world!')

fpgui.fpgFormOnClick(0,TheProcF)

fpgui.fpgButtonCreate(0,0,-1) ; fpgui.fpgButtonSetPosition(0,0, 15, 10 , 150 , 40) fpgui.fpgButtonSetText(0,0, 'BUTTON1')

fpgui.fpgButtonCreate(0,1,-1) ; fpgui.fpgButtonSetPosition(0,1, 15, 70 , 150, 40) fpgui.fpgButtonSetText(0,1, 'Clickme')

fpgui.fpgFormShow(0) fpgui.fpgRun()

Here the error message if i click on form :

Traceback (most recent call last): File "_ctypes/callbacks.c", line 314, in 'calling callback function' TypeError: TheProc() takes exactly 1 argument (0 given)

What is wrong ?

Many thanks.


From rosuav at gmail.com  Thu Mar 20 19:18:25 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 10:18:25 +1100
Subject: running python 2 vs 3
In-Reply-To: <8738icmrw4.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
 <87pplgoac6.fsf@elektro.pacujo.net>
 <mailman.8322.1395351136.18130.python-list@python.org>
 <8738icmrw4.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmoOtEd6+Bb4dqqwr0_sedENWZbSF6ER3k-9tugf6mTXLQ@mail.gmail.com>

On Fri, Mar 21, 2014 at 9:23 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Ned Batchelder <ned at nedbatchelder.com>:
>> On 3/20/14 4:59 PM, Marko Rauhamaa wrote:
>>> Well, with proper care, I suppose the same code base could support perl
>>> as well. ;)
>>
>> I'm not sure how to take this comment. I feel like you are mocking my
>> choice. I wanted to make coverage.py available to as broad an audience
>> as possible, something that I think is worthwhile. Yes, there was an
>> engineering cost, but the tradeoff was worth it.
>
> I can't judge if your particular choice was the right one. My only point
> is that python2 and python3 are so far apart as to be regarded as
> independent languages.

They're definitely not independent languages. The biggest change is
str/unicode->bytes/str, and you can get part of that in Python 2.6/2.7
with "from __future__ import unicode_literals". You may still run into
problems with some functions that expect str and won't take unicode
(or vice versa), but it's easy to make code that runs across both
versions that way. Then toss in "from __future__ import
print_function" and happily use the expanded features of print, or go
for the lowest common denominator:

print("some single string")

which works happily in all versions of Python.

I've written code that runs on 2.6+/3.2+. (Or maybe it's 3.1+;
whichever version Debian Squeeze ships with.) It's pretty easy. It's
certainly a lot easier than writing code that runs as either Pike or
C++, for instance. THOSE are independent languages. (And yes, I've
written that sort of code. Had a #define block up the top to handle
some naming differences, and then restricted myself to a *really*
narrow set of common operations. Was a neat way to prove correctness,
though.)

ChrisA


From harrismh777 at gmail.com  Thu Mar 20 19:42:03 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 20 Mar 2014 18:42:03 -0500
Subject: CallBack function in C Libraries.
References: <a9908cb7-3566-42a8-a468-8179ac1df7ab@googlegroups.com>
Message-ID: <lgfucb$4q7$1@speranza.aioe.org>

On 3/20/14 6:16 PM, fiensproto at gmail.com wrote:

> def TheProc(c_int): fpgui.fpgFormWindowTitle(0, 'Boum')
> return 0

> TheProcF = CMPFUNC(TheProc)

> Traceback (most recent call last): File "_ctypes/callbacks.c",
> line 314, in 'calling callback function' TypeError: TheProc() takes
> exactly 1 argument (0 given)

> What is wrong ?

You defined TheProc(c_init) to take exactly 1 argument.

But when you called it, you didn't provide the argument.

So, you got a traceback indicating that TheProc() takes exactly one 
argument.

Give the function call its required argument and the error will go 
away... well, at least that one.


Cheers


From fiensproto at gmail.com  Thu Mar 20 19:56:43 2014
From: fiensproto at gmail.com (fiensproto at gmail.com)
Date: Thu, 20 Mar 2014 16:56:43 -0700 (PDT)
Subject: CallBack function in C Libraries.
In-Reply-To: <lgfucb$4q7$1@speranza.aioe.org>
References: <a9908cb7-3566-42a8-a468-8179ac1df7ab@googlegroups.com>
 <lgfucb$4q7$1@speranza.aioe.org>
Message-ID: <e469fc0a-596c-40b6-8b27-751a4fe84d85@googlegroups.com>

> Give the function call its required argument and the error will go 
> 
> away... well, at least that one.

Yep, many thanks for the answer.
But... im totally beginner with Python.
I develop in Pascal and C and want to understand the basics of Python.

In concrete, what must i change in the code ?

Many thanks.


From dihedral88888 at gmail.com  Thu Mar 20 20:04:57 2014
From: dihedral88888 at gmail.com (88888 Dihedral)
Date: Thu, 20 Mar 2014 17:04:57 -0700 (PDT)
Subject: CallBack function in C Libraries.
In-Reply-To: <e469fc0a-596c-40b6-8b27-751a4fe84d85@googlegroups.com>
References: <a9908cb7-3566-42a8-a468-8179ac1df7ab@googlegroups.com>
 <lgfucb$4q7$1@speranza.aioe.org>
 <e469fc0a-596c-40b6-8b27-751a4fe84d85@googlegroups.com>
Message-ID: <fc708c65-e591-4186-801a-a0bbeaf87ef0@googlegroups.com>

On Friday, March 21, 2014 7:56:43 AM UTC+8, fiens... at gmail.com wrote:
> > Give the function call its required argument and the error will go 
> 
> > 
> 
> > away... well, at least that one.
> 
> 
> 
> Yep, many thanks for the answer.
> 
> But... im totally beginner with Python.
> 
> I develop in Pascal and C and want to understand the basics of Python.
> 
> 
> 
> In concrete, what must i change in the code ?
> 
> 
> 
> Many thanks.

Python is a dynamical typed functional
language with OOP supports in the 
revisons, and well suited in the 
giga-byte dram capacity 
personal toy era that can relplace 
her mother lisp's unrealized AI 
project .


From laguna-mc at mail.com  Thu Mar 20 20:16:09 2014
From: laguna-mc at mail.com (laguna-mc at mail.com)
Date: Thu, 20 Mar 2014 20:16:09 -0400
Subject: Installing ssdeep on Portable Python /advice
Message-ID: <20140321001609.63150@gmx.com>

Portable Python 2.7 for Windows, the Python application have dependency on ssdeep-2.10, which is a binary exe.

The ssdeep (libfuzzy) installation example was shown for Linux platform only:
----
a) libfuzzy can be installed via apt-get:

 ? ?$ sudo apt-get install libfuzzy2

b) to install libfuzzy from source, download the gzipped tarball from http://ssdeep.sourceforge.net/#download, then run:

 ? ?$ tar -zxvf ssdeep-2.10.tar.gz
 ? ?$ cd ssdeep-2.10 && ./configure && make && sudo make install
-----
I need install it on PortablePython for Windows, so it's not clear how to make this: where should be placed ssdeep Windows binary files, that Python application can found it?


From breamoreboy at yahoo.co.uk  Thu Mar 20 20:27:42 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Fri, 21 Mar 2014 00:27:42 +0000
Subject: Installing ssdeep on Portable Python /advice
In-Reply-To: <20140321001609.63150@gmx.com>
References: <20140321001609.63150@gmx.com>
Message-ID: <lgg11k$l6e$1@ger.gmane.org>

On 21/03/2014 00:16, laguna-mc at mail.com wrote:
> Portable Python 2.7 for Windows, the Python application have dependency on ssdeep-2.10, which is a binary exe.
>
> The ssdeep (libfuzzy) installation example was shown for Linux platform only:
> ----
> a) libfuzzy can be installed via apt-get:
>
>      $ sudo apt-get install libfuzzy2
>
> b) to install libfuzzy from source, download the gzipped tarball from http://ssdeep.sourceforge.net/#download, then run:
>
>      $ tar -zxvf ssdeep-2.10.tar.gz
>      $ cd ssdeep-2.10 && ./configure && make && sudo make install
> -----
> I need install it on PortablePython for Windows, so it's not clear how to make this: where should be placed ssdeep Windows binary files, that Python application can found it?
>

You've changed the subject line but other than that this appears to be 
identical to the question you posed almost exactly six hours ago.  It is 
considered polite to wait for at least 24 hours before again asking for 
assistance.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From steve+comp.lang.python at pearwood.info  Thu Mar 20 20:29:55 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 21 Mar 2014 00:29:55 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <lgfhup$sth$1@speranza.aioe.org> <bp14sbFaoq9U2@mid.individual.net>
Message-ID: <532b8803$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 20 Mar 2014 21:28:43 +0000, notbob wrote:

> On 2014-03-20, Mark H Harris <harrismh777 at gmail.com> wrote:
> 
>> When I call python2 that means python2.7.6 /
>>
>> When I call python3 that means python3.3.4 /
>>
>> I can also call python2.7, which is 2.7.2 /
>>
>> You get the idea.   There is no one set rule, because there are many
>> distros (gnu/linux) that use python at various versions, and they all
>> us different setups.  Really , you need an install script to snoop out
>> the configurables.
> 
> Weeping Chryst on the cross!!.  No wonder the latest O'Reilly book,
> Learning Python, 5th ed, is 1600 pgs.  I coulda swore someone sed python
> is easy.  ;)


This has nothing to do with Python. It has to do with the way executables 
(applications) are mapped to file names on Unix and Unix-like systems. 
And that in turn is not terribly different from the way that it works on 
Windows as well.

When you type "python" at the command prompt, your system locates an 
executable named "python", then runs it. If you wanted to be annoying, 
you could alias or link the python name to a completely different 
language. Or use a different name altogether:

steve at orac:~$ alias snake=python
steve at orac:~$ snake
Python 2.6.6 (r266:84292, Dec 27 2010, 00:02:40)
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.


This has nothing to do with Python, it's the way Linux works.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Thu Mar 20 20:32:48 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 21 Mar 2014 00:32:48 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <lgfeb3$clj$1@cabale.usenet-fr.net>
 <mailman.8315.1395347215.18130.python-list@python.org>
Message-ID: <532b88b0$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 20 Mar 2014 16:26:39 -0400, Ned Batchelder wrote:

> On 3/20/14 3:07 PM, Eric Jacoboni wrote:
>> Le 20/03/2014 16:21, Marko Rauhamaa a ?crit :
>>
>>
>>> All tutorials will tell you to start it with
>>>
>>>     #!/usr/bin/env python
>>>
>>> which will start python2 on all (?) existing linux distros, but is
>>> expected to start python3 within the next decade.
>>
>> With Arch-Linux, python is python3...
>>
>>
> Yes, and they have been told many times that this was foolish and wrong,
> but it persists, much to our pain.

How bizarre. I've been looking forward with great pleasure to Fedora 
moving to Python 3 as the standard system Python, expecting that this 
move from one of the big distros will start a chain reaction of others 
doing the same thing. Perhaps Arch-Linux is guilty of being prematurely 
Python 3, a little like those people hauled up to explain themselves to 
the House Unamerican Activities Committee to explain why they were a 
"premature anti-fascist".

I have no idea what "our pain" you are referring to, or who "our" refers 
to. In the three or five years or so since Arch-Linux moved to Python 3 
by default, I don't recall ever seeing even a single email from somebody 
confused by Arch-Linux's move, not here, or on the tutor mailing list, or 
on Python-Dev or Python-Ideas. Nor have I seen any signs of difficulty or 
confusion on Python-related blogs, or StackOverflow.

That's not to say that there has been absolutely none at all. The 
Internet is a big place, and I daresay I've missed something. But given 
how small the Arch-Linux share of the Linux space is, I would be 
astonished if their move caused more than a tiny little ripple. Perhaps a 
paper-cut worth of pain. I expect that there have been far more angry 
words written over this issue than the actual consequences of the move 
itself. Unless you're in the unfortunate situation of having to migrate 
and maintain scripts across a network of mixed Linux distros including 
some that are Arch-Linux, it's difficult to see exactly what pain they 
could be causing even in principle.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Thu Mar 20 20:37:04 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 21 Mar 2014 00:37:04 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
Message-ID: <532b89af$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 20 Mar 2014 16:53:25 -0400, Ned Batchelder wrote:

> On 3/20/14 4:42 PM, Marko Rauhamaa wrote:
>> Ned Batchelder <ned at nedbatchelder.com>:
>>
>>> Plenty of people have adopted a dual-support strategy, with one code
>>> base that supports both Python 2 and Python 3. The six module can help
>>> a great deal with this.
>>
>> I wonder how easy the resulting code is to the eyes and how easy it is
>> for the casual maintainer to accidentally break the delicate balance.
>> In a word, I wouldn't go there. Stay with Python2 as long as you must
>> and then, migrate and leave it behind.
> 
> This is fine advice for applications, but tools, libraries, and
> frameworks may want to support more than one version at the same time.

+1

Actually, even applications may want to support multiple versions. If I 
have a Python script that does something, I might not want to tie it to 
one specific version. In principle there's not much difference between 
"this will run under Python 2.6 and 2.7" and "this will run under Python 
2.7 and 3.3". In practice, it's a little trickier to cross the 2/3 
barrier than the 2.6/2.7 barrier. But it is still quite achievable, with 
a little extra effort. 

But you know that even better than I -- I take my hat off to you for 
supporting all the way back to Python 2.3, that is far more dedicated 
than I am.

In my experience, such as it is, the hard part about writing code that 
works from 2.4 to 3.4 is not the 3 versions but the 2.4 and 2.5 versions.


> It's an extreme case, but the latest released version of coverage.py
> supports Python 2.3 through 3.3 with one code base.  To do it, there's a
> compatibility layer (akin to six).  Then you stay away from features
> that aren't available on all versions.  In a few places, you might need
> to have version checks, and the code can get a little idiomatic to
> continue to work.
> 
> It's a tradeoff: you have to decide for yourself whether the effort is
> worth the benefit.  I was glad to be able to drop support for 2.3, 2.4,
> and 2.5, and now only support 2.6-3.4 in coverage.py.

Sounds like your experience agrees with mine.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Thu Mar 20 20:59:57 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 21 Mar 2014 00:59:57 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
 <mailman.8319.1395348268.18130.python-list@python.org>
 <87txasoaqi.fsf@elektro.pacujo.net>
Message-ID: <532b8f0d$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 20 Mar 2014 22:50:45 +0200, Marko Rauhamaa wrote:

> Mark Lawrence <breamoreboy at yahoo.co.uk>:
> 
>> On 20/03/2014 20:30, Marko Rauhamaa wrote:
>>> I must say, though, that Python3 destroyed "print" forever for me. To
>>> avoid nausea, I write sys.stdout.write() in all Python3 code.
>>
>> Not for me, I was using from __future__ import print_function for years
>> so got used to typing those two extra brackets, plus print very kindly
>> inserts the newlines for me.
> 
> That very realization helped me wean myself from "print." Its sole
> raison d'?tre is the insertion of the newline, which it would be nicer
> to micromanage anyway; that's how it's done in other programming
> languages as well: C, perl, guile, ... (Well, ok, "echo" is the
> exception.)

echo is not "the" exception. *Many* languages handle the newline when 
printing: Pascal, Ruby, Io, Dylan, Haskell, Rebol, Tcl, Perl6, Java, 
Ocaml, ... either add a newline by default, or provide two functions for 
printing, one which adds newline and one which doesn't.

The rule of three applies here: anything you do in three different places 
ought to be managed by a function. Printing a newline at the end of a 
line of output is *incredibly* common. Any language which fails to 
provide a print-with-newline function is, frankly, sub-standard.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ned at nedbatchelder.com  Thu Mar 20 21:06:24 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Thu, 20 Mar 2014 21:06:24 -0400
Subject: running python 2 vs 3
In-Reply-To: <532b88b0$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <lgfeb3$clj$1@cabale.usenet-fr.net>
 <mailman.8315.1395347215.18130.python-list@python.org>
 <532b88b0$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgg3a1$r94$1@ger.gmane.org>

On 3/20/14 8:32 PM, Steven D'Aprano wrote:
> On Thu, 20 Mar 2014 16:26:39 -0400, Ned Batchelder wrote:
>
>> On 3/20/14 3:07 PM, Eric Jacoboni wrote:
>>> Le 20/03/2014 16:21, Marko Rauhamaa a ?crit :
>>>
>>>
>>>> All tutorials will tell you to start it with
>>>>
>>>>      #!/usr/bin/env python
>>>>
>>>> which will start python2 on all (?) existing linux distros, but is
>>>> expected to start python3 within the next decade.
>>>
>>> With Arch-Linux, python is python3...
>>>
>>>
>> Yes, and they have been told many times that this was foolish and wrong,
>> but it persists, much to our pain.
>
> How bizarre. I've been looking forward with great pleasure to Fedora
> moving to Python 3 as the standard system Python, expecting that this
> move from one of the big distros will start a chain reaction of others
> doing the same thing. Perhaps Arch-Linux is guilty of being prematurely
> Python 3, a little like those people hauled up to explain themselves to
> the House Unamerican Activities Committee to explain why they were a
> "premature anti-fascist".
>

My understanding is that Fedora's move will not include making the word 
"python" mean Python 3.  Their move means that Python 3 will be 
installed by default, and that their Python programs that are part of 
the distro will be Python 3 programs.  They can still refer to it as 
"python3".

> I have no idea what "our pain" you are referring to, or who "our" refers
> to. In the three or five years or so since Arch-Linux moved to Python 3
> by default, I don't recall ever seeing even a single email from somebody
> confused by Arch-Linux's move, not here, or on the tutor mailing list, or
> on Python-Dev or Python-Ideas. Nor have I seen any signs of difficulty or
> confusion on Python-related blogs, or StackOverflow.

In the #python IRC channel, there's a steady flow of people who run 
programs they find online, and they get a syntax error on "print", and 
we say, "Arch?" and they say, "yup".

Perhaps I overstated the amount of pain.  But Arch's move prompted a PEP 
to be written explaining what the word "python" should mean:

http://python.org/dev/peps/pep-0394/

Note that they say there that "for the time being" the word python 
should mean Python 2, anticipating that eventually it will be OK to 
change it to Python 3.  But I think that change would always cause 
confusion, and we should not change it over.  I understand that this is 
a controversial view, and don't hold it strongly enough to defend it. :)

>
> That's not to say that there has been absolutely none at all. The
> Internet is a big place, and I daresay I've missed something. But given
> how small the Arch-Linux share of the Linux space is, I would be
> astonished if their move caused more than a tiny little ripple. Perhaps a
> paper-cut worth of pain.

It caused enough of a ripple to get PEP 394 written so that people 
wouldn't do it again.

I expect that there have been far more angry
> words written over this issue than the actual consequences of the move
> itself. Unless you're in the unfortunate situation of having to migrate
> and maintain scripts across a network of mixed Linux distros including
> some that are Arch-Linux, it's difficult to see exactly what pain they
> could be causing even in principle.
>
>
>
>


-- 
Ned Batchelder, http://nedbatchelder.com



From roy at panix.com  Thu Mar 20 21:06:42 2014
From: roy at panix.com (Roy Smith)
Date: Thu, 20 Mar 2014 21:06:42 -0400
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
 <mailman.8319.1395348268.18130.python-list@python.org>
 <87txasoaqi.fsf@elektro.pacujo.net>
 <532b8f0d$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-C004D1.21064220032014@news.panix.com>

In article <532b8f0d$0$29994$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> The rule of three applies here: anything you do in three different places 
> ought to be managed by a function.

I prefer the rule of two :-)


From rosuav at gmail.com  Thu Mar 20 21:10:21 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 12:10:21 +1100
Subject: running python 2 vs 3
In-Reply-To: <532b88b0$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
 <lgfeb3$clj$1@cabale.usenet-fr.net>
 <mailman.8315.1395347215.18130.python-list@python.org>
 <532b88b0$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmrP0-ZfXWe4B9Ss-NO74xFqMyLCKZXGAfKGsji5fDH6zA@mail.gmail.com>

On Fri, Mar 21, 2014 at 11:32 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Perhaps Arch-Linux is guilty of being prematurely Python 3...
>
> I have no idea what "our pain" you are referring to, or who "our" refers
> to. In the three or five years or so since Arch-Linux moved to Python 3
> by default, I don't recall ever seeing even a single email from somebody
> confused by Arch-Linux's move, not here, or on the tutor mailing list, or
> on Python-Dev or Python-Ideas. Nor have I seen any signs of difficulty or
> confusion on Python-related blogs, or StackOverflow.
>
> That's not to say that there has been absolutely none at all.

There definitely has been a little. Scripts that began with a "python"
shebang and assumed 2.x would suddenly fail on Arch. But not a huge
amount of confusion. I expect that there'll be a progressive shift -
more distros will start shipping 3.x under the name "python", so
script authors will be more and more aware of the difference, and
before long we'll settle on explicit use of "python2" or "python3" for
anything that matters. Think of the bug reports: "Your program doesn't
work on Ubuntu 14.04, but change the shebang and it'll work, without
breaking it for anything else". Easy fix. And then once Debian and Red
Hat move to 3.x as the default system Python, everyone'll use
"python2" for 2.7 (by that time, I doubt 2.6 or earlier will be
supported much anywhere) and "python" for 3.x, and the transition will
be complete.

ChrisA


From rosuav at gmail.com  Thu Mar 20 21:15:19 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 12:15:19 +1100
Subject: running python 2 vs 3
In-Reply-To: <532b8f0d$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
 <mailman.8319.1395348268.18130.python-list@python.org>
 <87txasoaqi.fsf@elektro.pacujo.net>
 <532b8f0d$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqLn2mJFN1VgAiyEtH43ZW8hWrjfZK1AnWC1T60TATJtQ@mail.gmail.com>

On Fri, Mar 21, 2014 at 11:59 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> The rule of three applies here: anything you do in three different places
> ought to be managed by a function. Printing a newline at the end of a
> line of output is *incredibly* common. Any language which fails to
> provide a print-with-newline function is, frankly, sub-standard.

I wouldn't go that far. There are plenty of languages where the
default (printf, write, werror, etc) doesn't add the newline, and I
wouldn't call the *language* sub-standard for that. But yes, it does
bug me now and then. I use my "say" function to produce one or more
lines of output in Gypsum, and it guarantees complete lines (because
the system works with lines, not streams of characters); and then if I
use the "werror" function to write to stderr, I have to remember to
add the newline. However, I think Py2's print statement has way too
many weirdnesses - the trailing comma (reminiscent of BASIC, where I
never liked it either), the whole "soft space" concept, etc. Py3's
print function, with the keyword end="", is a lot better, though still
a tad verbose. (I don't know of any solution to that.)

ChrisA


From ned at nedbatchelder.com  Thu Mar 20 21:20:47 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Thu, 20 Mar 2014 21:20:47 -0400
Subject: running python 2 vs 3
In-Reply-To: <lgg3a1$r94$1@ger.gmane.org>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <lgfeb3$clj$1@cabale.usenet-fr.net>
 <mailman.8315.1395347215.18130.python-list@python.org>
 <532b88b0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgg3a1$r94$1@ger.gmane.org>
Message-ID: <lgg44v$tee$1@ger.gmane.org>

On 3/20/14 9:06 PM, Ned Batchelder wrote:
> On 3/20/14 8:32 PM, Steven D'Aprano wrote:
>> On Thu, 20 Mar 2014 16:26:39 -0400, Ned Batchelder wrote:
>>
>>> On 3/20/14 3:07 PM, Eric Jacoboni wrote:
>>>> Le 20/03/2014 16:21, Marko Rauhamaa a ?crit :
>>>>
>>>>
>>>>> All tutorials will tell you to start it with
>>>>>
>>>>>      #!/usr/bin/env python
>>>>>
>>>>> which will start python2 on all (?) existing linux distros, but is
>>>>> expected to start python3 within the next decade.
>>>>
>>>> With Arch-Linux, python is python3...
>>>>
>>>>
>>> Yes, and they have been told many times that this was foolish and wrong,
>>> but it persists, much to our pain.
>>
>> How bizarre. I've been looking forward with great pleasure to Fedora
>> moving to Python 3 as the standard system Python, expecting that this
>> move from one of the big distros will start a chain reaction of others
>> doing the same thing. Perhaps Arch-Linux is guilty of being prematurely
>> Python 3, a little like those people hauled up to explain themselves to
>> the House Unamerican Activities Committee to explain why they were a
>> "premature anti-fascist".
>>
>
> My understanding is that Fedora's move will not include making the word
> "python" mean Python 3.  Their move means that Python 3 will be
> installed by default, and that their Python programs that are part of
> the distro will be Python 3 programs.  They can still refer to it as
> "python3".

 From http://fedoraproject.org/wiki/Changes/Python_3_as_Default :

    Users shouldn't notice any changes, ... /usr/bin/python will still
    point to Python 2 and depending on result of discussions with FPC,
    "yum install python-foo" will still install Python 2 version of
    the package.




-- 
Ned Batchelder, http://nedbatchelder.com



From ethan at stoneleaf.us  Thu Mar 20 21:23:55 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Thu, 20 Mar 2014 18:23:55 -0700
Subject: running python 2 vs 3
In-Reply-To: <532b89af$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
 <532b89af$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <532B94AB.7000709@stoneleaf.us>

On 03/20/2014 05:37 PM, Steven D'Aprano wrote:
>
> In my experience, such as it is, the hard part about writing code that
> works from 2.4 to 3.4 is not the 3 versions but the 2.4 and 2.5 versions.

+1000!  (yes, that's factorial  ;)

--
~Ethan~


From cs at zip.com.au  Thu Mar 20 21:33:13 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Fri, 21 Mar 2014 12:33:13 +1100
Subject: Question about Source Control
In-Reply-To: <CAPTjJmq4MkGjOY_en-v=hA=3oJ1sef_uF8BbQ9nm6r8nPMwTgA@mail.gmail.com>
References: <CAPTjJmq4MkGjOY_en-v=hA=3oJ1sef_uF8BbQ9nm6r8nPMwTgA@mail.gmail.com>
Message-ID: <20140321013313.GA58343@cskk.homeip.net>

On 21Mar2014 09:34, Chris Angelico <rosuav at gmail.com> wrote:
> On Fri, Mar 21, 2014 at 9:19 AM, Gregory Ewing
> > Also, unless the project is truly ancient, the
> > whole history might not be as big as you expect.
> > The code presumably grew to its present size
> > incrementally, in an approximately monotonic
> > manner, so the sum of all the diffs is probably
> > about the same order of magnitude as the current
> > code size.
> >
> > As an experiment, I just cloned a copy of the
> > CPython repository, and it's about 300MB. A
> > tarball of Python 3.2 that I downloaded and
> > compiled earlier is about 75MB. That's a ratio
> > of about 4, and CPython is a pretty ancient
> > project!
> 
> Yep! But cloning requires that you have Mercurial installed and, more
> importantly, know how to use it. We don't have a huge proliferation of
> source control systems these days, but if someone says "Our code is
> available via Perforce", I'm going to just look for a tarball
> download, rather than figure out a source control system I don't know.

Someone intending to clone the project and develop will probably
want the whole repository; as Gregory says - they can then easily
push/pull with others.

For Frank, the size of the repo is not the size of the bare code *
number of changesets. There are many diff-level steps in there,
making for a much smaller size. And code is small; really really
small.

Regarding having Mercurial installed, that is very easy, and after
you've gone (eg):

  hg clone https://bitbucket.org/cameron_simpson/css my-copy-of-cameron's-css

(or wherever the public repository is published), you can of course
then walk away and work. You no longer need the public copy at all.

With a DVCS the threshold is low and the advantages are high (hg
or git; I'm an hg person myself).

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

I am returning this otherwise good typing paper to you because someone has
printed gibberish all over it and put your name at the top.
        - English Professor, Ohio University


From rhodri at wildebst.org.uk  Thu Mar 20 22:01:51 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Fri, 21 Mar 2014 02:01:51 -0000
Subject: CallBack function in C Libraries.
References: <a9908cb7-3566-42a8-a468-8179ac1df7ab@googlegroups.com>
 <lgfucb$4q7$1@speranza.aioe.org>
 <e469fc0a-596c-40b6-8b27-751a4fe84d85@googlegroups.com>
Message-ID: <op.xc1uldoj5079vu@gnudebeest>

On Thu, 20 Mar 2014 23:56:43 -0000, <fiensproto at gmail.com> wrote:

>> Give the function call its required argument and the error will go
>>
>> away... well, at least that one.
>
> Yep, many thanks for the answer.
> But... im totally beginner with Python.
> I develop in Pascal and C and want to understand the basics of Python.
>
> In concrete, what must i change in the code ?

In abstract, exactly the same thing that you would change if a C compiler  
had complained to you that you had failed to give a function call the  
right number of arguments.  More than that I have no idea; it's your code,  
presumably you know what it should be doing.  I have absolutely no idea  
how TheProc() is being called by your widgets.  Are you sure it should be  
declared as taking a single parameter?

I'm afraid it doesn't help that GoogleGroups has badly mangled the  
formatting of your code.  I'm not quite sure what to suggest since it  
isn't one of the usual problems, but you might find reading  
https://wiki.python.org/moin/GoogleGroupsPython helpful.  It will  
certainly help with the double-spacing in your quote above.

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From rosuav at gmail.com  Thu Mar 20 22:14:21 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 13:14:21 +1100
Subject: Question about Source Control
In-Reply-To: <20140321013313.GA58343@cskk.homeip.net>
References: <CAPTjJmq4MkGjOY_en-v=hA=3oJ1sef_uF8BbQ9nm6r8nPMwTgA@mail.gmail.com>
 <20140321013313.GA58343@cskk.homeip.net>
Message-ID: <CAPTjJmpg6veAu0aC2pKNuaApk697m4_x=pQ10VE6UOGhxNtbBA@mail.gmail.com>

On Fri, Mar 21, 2014 at 12:33 PM, Cameron Simpson <cs at zip.com.au> wrote:
> Regarding having Mercurial installed, that is very easy, and after
> you've gone (eg):
>
>   hg clone https://bitbucket.org/cameron_simpson/css my-copy-of-cameron's-css
>
> (or wherever the public repository is published), you can of course
> then walk away and work. You no longer need the public copy at all.
>
> With a DVCS the threshold is low and the advantages are high (hg
> or git; I'm an hg person myself).

Yes, it's not hard to get Mercurial. And it's not hard to get git. But
it is an extra barrier, and trying to tell people they need
this-that-and-the-other just to get your software is a pain.
Personally, I'm quite happy fetching from either git or hg, because
I'm at least broadly familiar with both (more with git), but if it's
something I'm *not* familiar with (cvs? Haven't used it in forever),
less happy.

ChrisA


From rosuav at gmail.com  Thu Mar 20 22:18:29 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 13:18:29 +1100
Subject: running python 2 vs 3
In-Reply-To: <roy-C004D1.21064220032014@news.panix.com>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
 <mailman.8319.1395348268.18130.python-list@python.org>
 <87txasoaqi.fsf@elektro.pacujo.net>
 <532b8f0d$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-C004D1.21064220032014@news.panix.com>
Message-ID: <CAPTjJmo+ASg+7ixYc57u7MNS8pnhtZxbDV45pQK24LYFcT-iVw@mail.gmail.com>

On Fri, Mar 21, 2014 at 12:06 PM, Roy Smith <roy at panix.com> wrote:
> In article <532b8f0d$0$29994$c3e8da3$5496439d at news.astraweb.com>,
>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>
>> The rule of three applies here: anything you do in three different places
>> ought to be managed by a function.
>
> I prefer the rule of two :-)

The way I explain it is: Three is a rule of thumb. Sometimes it's
blatantly obvious at two, and other times you need four or five
similar pieces of code before you can see which part should become the
function. If the code's absolutely identical and reasonably
long/complex, then yes, two's all you need, but how often is that?
Usually it's similar, rather than congruent... err I mean identical.
That's where the third usage comes in. Or if it's maybe 2-3 lines,
used in two places, it doesn't necessarily need to be a function.
Again, a third usage is a strong hint that it should be broken out.

The rule doesn't say that anything that *isn't* in three places yet
should *not* be broken out. :)

ChrisA


From rustompmody at gmail.com  Thu Mar 20 22:20:21 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 20 Mar 2014 19:20:21 -0700 (PDT)
Subject: running python 2 vs 3
In-Reply-To: <mailman.8320.1395348816.18130.python-list@python.org>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
 <532B4750.2090006@yahoo.com> <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
Message-ID: <9663dc26-104b-4b02-bfca-525c86d07bb9@googlegroups.com>

On Friday, March 21, 2014 2:23:25 AM UTC+5:30, Ned Batchelder wrote:
> On 3/20/14 4:42 PM, Marko Rauhamaa wrote:
> > Ned Batchelder :
> >> Plenty of people have adopted a dual-support strategy, with one code
> >> base that supports both Python 2 and Python 3. The six module can help
> >> a great deal with this.
> > I wonder how easy the resulting code is to the eyes and how easy it is
> > for the casual maintainer to accidentally break the delicate balance. In
> > a word, I wouldn't go there. Stay with Python2 as long as you must and
> > then, migrate and leave it behind.

> This is fine advice for applications, but tools, libraries, and 
> frameworks may want to support more than one version at the same time.

> It's an extreme case, but the latest released version of coverage.py 
> supports Python 2.3 through 3.3 with one code base.  To do it, there's a 
> compatibility layer (akin to six).  Then you stay away from features 
> that aren't available on all versions.  In a few places, you might need 
> to have version checks, and the code can get a little idiomatic to 
> continue to work.

> It's a tradeoff: you have to decide for yourself whether the effort is 
> worth the benefit.  I was glad to be able to drop support for 2.3, 2.4, 
> and 2.5, and now only support 2.6-3.4 in coverage.py.

Ned is talking to (and from) a lib-writer perspective
Marko is talking from noob perspective (which is what the OP looks like)

Good to choose our hats appropriately


From wuwei23 at gmail.com  Thu Mar 20 22:37:46 2014
From: wuwei23 at gmail.com (alex23)
Date: Fri, 21 Mar 2014 12:37:46 +1000
Subject: running python 2 vs 3
In-Reply-To: <mailman.8325.1395353168.18130.python-list@python.org>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <bp0hk7F613oU3@mid.individual.net>
 <mailman.8304.1395332703.18130.python-list@python.org>
 <bp0lohF7aqdU3@mid.individual.net> <lgfe9q$9hv$1@reader1.panix.com>
 <mailman.8325.1395353168.18130.python-list@python.org>
Message-ID: <lgg8lq$74s$1@dont-email.me>

> On 3/20/2014 3:07 PM, John Gordon wrote:
> There are two ways (at least!) to run a python script:

 > On 21/03/2014 8:05 AM, Terry Reedy wrote:
> 3. [...]

"Our chief weapon is..."



From dtran.ru at gmail.com  Thu Mar 20 22:50:13 2014
From: dtran.ru at gmail.com (dtran.ru at gmail.com)
Date: Thu, 20 Mar 2014 19:50:13 -0700 (PDT)
Subject: Python - Caeser Cipher Not Giving Right Output
Message-ID: <7eee0f2b-0d5f-409e-ae4e-8c9c1af31d74@googlegroups.com>

Hello good people I am working on a caeser cipher program for class. However, I ran into a problem with my outputs. Up to a certain point for example:

1. two('y', 'z')

Would give a '\x92' output instead of a 'x' output.

Currently this is my code so far:

def chartonum(ch):
    return ord(ch) - 97 

def numtochar(n):
    return chr(n + 97) 

def two(c1 , c2):
    c1 = chartonum(c1)
    c2 = chartonum(c2)
    return numtochar(c1 + c2 %26)

I am thinking I have messed up on my mod 26, however, I am at a lost where I might have went wrong in that. Any help would be appreciated.


From davea at davea.name  Thu Mar 20 23:16:50 2014
From: davea at davea.name (Dave Angel)
Date: Thu, 20 Mar 2014 23:16:50 -0400 (EDT)
Subject: Python - Caeser Cipher Not Giving Right Output
References: <7eee0f2b-0d5f-409e-ae4e-8c9c1af31d74@googlegroups.com>
Message-ID: <lggall$ecu$1@ger.gmane.org>

 dtran.ru at gmail.com Wrote in message:
> Hello good people I am working on a caeser cipher program for class. However, I ran into a problem with my outputs. Up to a certain point for example:
> 
> 1. two('y', 'z')
> 
> Would give a '\x92' output instead of a 'x' output.
> 
> Currently this is my code so far:
> 
> def chartonum(ch):
>     return ord(ch) - 97 
> 
> def numtochar(n):
>     return chr(n + 97) 
> 
> def two(c1 , c2):
>     c1 = chartonum(c1)
>     c2 = chartonum(c2)
>     return numtochar(c1 + c2 %26)

You're missing some parentheses in that line. To test your
 understanding,  try picking some numbers for c1 and c2. Display
 c1 + c2 % 26, and see if the result is always between 0 and
 25.

Or look up the term precedence in your textbook.

> 
> I am thinking I have messed up on my mod 26, however, I am at a lost where I might have went wrong in that. Any help would be appreciated.
> 


-- 
DaveA



From steve+comp.lang.python at pearwood.info  Thu Mar 20 23:16:16 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 21 Mar 2014 03:16:16 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <lgfeb3$clj$1@cabale.usenet-fr.net>
 <mailman.8315.1395347215.18130.python-list@python.org>
 <532b88b0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8333.1395363997.18130.python-list@python.org>
Message-ID: <532baeff$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 20 Mar 2014 21:06:24 -0400, Ned Batchelder wrote:

> In the #python IRC channel, there's a steady flow of people who run
> programs they find online, and they get a syntax error on "print", and
> we say, "Arch?" and they say, "yup".

When you install random programs you find online without going through 
your package manager, you have no guarantee that all the dependencies 
will be met. Particularly of third-party libraries, but also of standard 
Python libraries too:

http://bytes.com/topic/python/answers/448757-how-enable-rotor-python-2-4-2-a

If your script uses xreadlines, rotor, or mpz, using "python" to refer to 
both pre-2.4 and post-2.4 will cause breakage. Likewise, I've seen Python 
2.6 break applications because it removed string exceptions. So I'm not 
seeing anything out of the ordinary with Arch: any version change has the 
possibility to break scripts. Python 3 is just more obvious because of 
the change to print, which I daresay is a little more common than rotor...

Arch happens to be at the bleeding edge of that, bless them, but if you 
use Arch, that's what you're letting yourself into. You know what they 
say -- even Slackware users think Arch users are nuts :-)

I've also seen scripts broken because the script used a hard-coded path 
to the Python executable, like /usr/bin/python or /usr/local/bin/python. Or 
because they've hard-coded the version number. Or because they didn't 
hard-code the version number. I haven't seen scripts broken because "env" 
has moved, but I guess that's only a matter of time. Frankly, hash-bang 
lines are a dirty hack, and like all dirty hacks, they work really well 
until they suddenly don't. 



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From dtran.ru at gmail.com  Thu Mar 20 23:23:49 2014
From: dtran.ru at gmail.com (dtran.ru at gmail.com)
Date: Thu, 20 Mar 2014 20:23:49 -0700 (PDT)
Subject: Python - Caeser Cipher Not Giving Right Output
In-Reply-To: <mailman.8341.1395371543.18130.python-list@python.org>
References: <7eee0f2b-0d5f-409e-ae4e-8c9c1af31d74@googlegroups.com>
 <mailman.8341.1395371543.18130.python-list@python.org>
Message-ID: <bda05813-d186-41ea-a40d-5d36f90a8fed@googlegroups.com>

On Thursday, March 20, 2014 11:16:50 PM UTC-4, Dave Angel wrote:
> dtran.ru at gmail.com Wrote in message:
> 
> > Hello good people I am working on a caeser cipher program for class. However, I ran into a problem with my outputs. Up to a certain point for example:
> 
> > 
> 
> > 1. two('y', 'z')
> 
> > 
> 
> > Would give a '\x92' output instead of a 'x' output.
> 
> > 
> 
> > Currently this is my code so far:
> 
> > 
> 
> > def chartonum(ch):
> 
> >     return ord(ch) - 97 
> 
> > 
> 
> > def numtochar(n):
> 
> >     return chr(n + 97) 
> 
> > 
> 
> > def two(c1 , c2):
> 
> >     c1 = chartonum(c1)
> 
> >     c2 = chartonum(c2)
> 
> >     return numtochar(c1 + c2 %26)
> 
> 
> 
> You're missing some parentheses in that line. To test your
> 
>  understanding,  try picking some numbers for c1 and c2. Display
> 
>  c1 + c2 % 26, and see if the result is always between 0 and
> 
>  25.
> 
> 
> 
> Or look up the term precedence in your textbook.
> 
> 
> 
> > 
> 
> > I am thinking I have messed up on my mod 26, however, I am at a lost where I might have went wrong in that. Any help would be appreciated.
> 
> > 
> 
> 
> 
> 
> 
> -- 
> 
> DaveA

Thanks for your input Dave. Would the line be:

return numtochar(c1 + c2 %26) 

c1 and c2 are lower-case letters. And I was wondering how I would add the partenthesis because I tried:

return numtochar(c1 + c2 (%26)) and it gave me an error. 


From rosuav at gmail.com  Thu Mar 20 23:34:28 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 14:34:28 +1100
Subject: running python 2 vs 3
In-Reply-To: <532baeff$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
 <lgfeb3$clj$1@cabale.usenet-fr.net>
 <mailman.8315.1395347215.18130.python-list@python.org>
 <532b88b0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8333.1395363997.18130.python-list@python.org>
 <532baeff$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmp+s-8nA_fypxw2bw=zqwR8ofsPnq2tAX-4E1mm6y1Mtw@mail.gmail.com>

On Fri, Mar 21, 2014 at 2:16 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> I haven't seen scripts broken because "env"
> has moved, but I guess that's only a matter of time.

That usage is extremely common, and isn't it also specified by POSIX?
I think that's about as dependable as you can get.

Course, it does depend on the user's $PATH...

ChrisA


From davea at davea.name  Fri Mar 21 00:02:39 2014
From: davea at davea.name (Dave Angel)
Date: Fri, 21 Mar 2014 00:02:39 -0400 (EDT)
Subject: Python - Caeser Cipher Not Giving Right Output
References: <7eee0f2b-0d5f-409e-ae4e-8c9c1af31d74@googlegroups.com>
 <mailman.8341.1395371543.18130.python-list@python.org>
 <bda05813-d186-41ea-a40d-5d36f90a8fed@googlegroups.com>
Message-ID: <lggdbi$ku6$1@ger.gmane.org>

 dtran.ru at gmail.com Wrote in message:
> On Thursday, March 20, 2014 11:16:50 PM UTC-4, Dave Angel wrote:
>> dtran.ru at gmail.com Wrote in message:
>> > 
>> 
>> > def two(c1 , c2):
>> 
>> >     c1 = chartonum(c1)
>> 
>> >     c2 = chartonum(c2)
>> 
>> >     return numtochar(c1 + c2 %26)
>> 
>> 
>> 
>> You're missing some parentheses in that line. To test your
>> 
>>  understanding,  try picking some numbers for c1 and c2. Display
>> 
>>  c1 + c2 % 26, and see if the result is always between 0 and
>> 
>>  25.
>> 
>> 
>> 
>> Or look up the term precedence in your textbook.
>> 
>
>> DaveA
> 
> Thanks for your input Dave. Would the line be:
> 
> return numtochar(c1 + c2 %26) 

That would be the line I tagged,  yes.

> 
> c1 and c2 are lower-case letters. 

No, they're not , you just got done overwriting the letters with
 numbers.   That's a bad habit, reusing local variables with data
 of different meanings,  but I was trying to focus on the line
 with the bug.


> And I was wondering how I would add the partenthesis because I tried:
> 
> return numtochar(c1 + c2 (%26)) and it gave me an error. 

Please help us to help you by actually showing the traceback. 
 Doesn't matter in this case, but...

What order do you want the add and the modulo to happen?  Use the
 parentheses to say so.  Or split it into two or more lines, with
 another variable. 

Perhaps you don't understand that % is an operator,  just like +
 and *.  If you were told to add a and b before multiplying by c,
 how would you write that? Try it, just as you tried the other
 experiment I recommended. 




-- 
DaveA



From steve+comp.lang.python at pearwood.info  Thu Mar 20 23:58:43 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 21 Mar 2014 03:58:43 GMT
Subject: Python - Caeser Cipher Not Giving Right Output
References: <7eee0f2b-0d5f-409e-ae4e-8c9c1af31d74@googlegroups.com>
 <mailman.8341.1395371543.18130.python-list@python.org>
 <bda05813-d186-41ea-a40d-5d36f90a8fed@googlegroups.com>
Message-ID: <532bb8f3$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 20 Mar 2014 20:23:49 -0700, dtran.ru wrote:

> Thanks for your input Dave. Would the line be:
> 
> return numtochar(c1 + c2 %26)

Yes, that's the line that Dave is talking about.

The critical part is that expression "c1 + c2 %26" which gets calculated 
before being passed on to numtochar. The % operator is a form of division 
(it returns the remainder after division, so 12%5 returns 2) and like the 
regular division operator / and multiplication * it has higher precedence 
than addition.

That means that "30 + 40 % 26" calculates the % part first:

30 + 40 % 26
=> 30 + 14
=> 54

What you probably want is to calculate the % last, not first. That means 
you need to perform the addition first. Use round brackets (parentheses) 
for that:

(30 + 40) % 26
=> 70 % 26
=> 18


Does that help?




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rustompmody at gmail.com  Fri Mar 21 00:02:58 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 20 Mar 2014 21:02:58 -0700 (PDT)
Subject: Python - Caeser Cipher Not Giving Right Output
In-Reply-To: <bda05813-d186-41ea-a40d-5d36f90a8fed@googlegroups.com>
References: <7eee0f2b-0d5f-409e-ae4e-8c9c1af31d74@googlegroups.com>
 <mailman.8341.1395371543.18130.python-list@python.org>
 <bda05813-d186-41ea-a40d-5d36f90a8fed@googlegroups.com>
Message-ID: <22bdaf7b-cace-46d8-a0d8-785fd5d83e74@googlegroups.com>

On Friday, March 21, 2014 8:53:49 AM UTC+5:30, wrote:
> On Thursday, March 20, 2014 11:16:50 PM UTC-4, Dave Angel wrote:
> > > Hello good people I am working on a caeser cipher program for class. However, I ran into a problem with my outputs. Up to a certain point for example:
> > > 1. two('y', 'z')
> > > Would give a '\x92' output instead of a 'x' output.
> > > Currently this is my code so far:
> > > def chartonum(ch):
> > >     return ord(ch) - 97 
> > > def numtochar(n):
> > >     return chr(n + 97) 
> > > def two(c1 , c2):
> > >     c1 = chartonum(c1)
> > >     c2 = chartonum(c2)
> > >     return numtochar(c1 + c2 %26)
> > You're missing some parentheses in that line. To test your
> >  understanding,  try picking some numbers for c1 and c2. Display
> >  c1 + c2 % 26, and see if the result is always between 0 and
> >  25.
> > Or look up the term precedence in your textbook.
> > > I am thinking I have messed up on my mod 26, however, I am at a lost where I might have went wrong in that. Any help would be appreciated.
> > -- 
> > DaveA

> Thanks for your input Dave. Would the line be:

> return numtochar(c1 + c2 %26) 

> c1 and c2 are lower-case letters. And I was wondering how I would add the partenthesis because I tried:

> return numtochar(c1 + c2 (%26)) and it gave me an error.

I suggest you put aside your assignment for 15 minutes. Then

1. Start up the python interpreter
2. Type ? + ?? % ???
   where the ?, ??, ??? take various values between 1 and 4
3. Try to put in parenthesis (ie '( )') here and there to modify your results
4. Then read the material on 'precedence' as Dave suggested


From dtran.ru at gmail.com  Fri Mar 21 00:23:24 2014
From: dtran.ru at gmail.com (dtran.ru at gmail.com)
Date: Thu, 20 Mar 2014 21:23:24 -0700 (PDT)
Subject: Python - Caeser Cipher Not Giving Right Output
In-Reply-To: <532bb8f3$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <7eee0f2b-0d5f-409e-ae4e-8c9c1af31d74@googlegroups.com>
 <mailman.8341.1395371543.18130.python-list@python.org>
 <bda05813-d186-41ea-a40d-5d36f90a8fed@googlegroups.com>
 <532bb8f3$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <32c74575-6387-45d5-ab8b-b414c035c98a@googlegroups.com>

On Thursday, March 20, 2014 11:58:43 PM UTC-4, Steven D'Aprano wrote:
> On Thu, 20 Mar 2014 20:23:49 -0700, dtran.ru wrote:
> 
> 
> 
> > Thanks for your input Dave. Would the line be:
> 
> > 
> 
> > return numtochar(c1 + c2 %26)
> 
> 
> 
> Yes, that's the line that Dave is talking about.
> 
> 
> 
> The critical part is that expression "c1 + c2 %26" which gets calculated 
> 
> before being passed on to numtochar. The % operator is a form of division 
> 
> (it returns the remainder after division, so 12%5 returns 2) and like the 
> 
> regular division operator / and multiplication * it has higher precedence 
> 
> than addition.
> 
> 
> 
> That means that "30 + 40 % 26" calculates the % part first:
> 
> 
> 
> 30 + 40 % 26
> 
> => 30 + 14
> 
> => 54
> 
> 
> 
> What you probably want is to calculate the % last, not first. That means 
> 
> you need to perform the addition first. Use round brackets (parentheses) 
> 
> for that:
> 
> 
> 
> (30 + 40) % 26
> 
> => 70 % 26
> 
> => 18
> 
> 
> 
> 
> 
> Does that help?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> -- 
> 
> Steven D'Aprano
> 
> http://import-that.dreamwidth.org/

Ooh I understand now! I've been coding for hours and exhaustion has gotten to my head. Many thanks all of you as I now know the source of my folly. 


From cs at zip.com.au  Fri Mar 21 01:17:00 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Fri, 21 Mar 2014 16:17:00 +1100
Subject: Question about Source Control
In-Reply-To: <CAPTjJmpg6veAu0aC2pKNuaApk697m4_x=pQ10VE6UOGhxNtbBA@mail.gmail.com>
References: <CAPTjJmpg6veAu0aC2pKNuaApk697m4_x=pQ10VE6UOGhxNtbBA@mail.gmail.com>
Message-ID: <20140321051700.GA35124@cskk.homeip.net>

On 21Mar2014 13:14, Chris Angelico <rosuav at gmail.com> wrote:
> On Fri, Mar 21, 2014 at 12:33 PM, Cameron Simpson <cs at zip.com.au> wrote:
> > Regarding having Mercurial installed, that is very easy, and after
> > you've gone (eg):
> >
> >   hg clone https://bitbucket.org/cameron_simpson/css my-copy-of-cameron's-css
> >
> > (or wherever the public repository is published), you can of course
> > then walk away and work. You no longer need the public copy at all.
> >
> > With a DVCS the threshold is low and the advantages are high (hg
> > or git; I'm an hg person myself).
> 
> Yes, it's not hard to get Mercurial. And it's not hard to get git. But
> it is an extra barrier, and trying to tell people they need
> this-that-and-the-other just to get your software is a pain.

I thought Frank's scenario involved someone cloning/forking the
software. I may have misread him though.

Of course, for people just wanting to build it or examine it,
tarballs and other archives are highly desirable.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

Rules of Optimization:
Rule 1: Don't do it.
Rule 2 (for experts only): Don't do it yet.
- M.A. Jackson


From frank at chagford.com  Fri Mar 21 01:40:42 2014
From: frank at chagford.com (Frank Millman)
Date: Fri, 21 Mar 2014 07:40:42 +0200
Subject: Question about Source Control
References: <CAPTjJmq4MkGjOY_en-v=hA=3oJ1sef_uF8BbQ9nm6r8nPMwTgA@mail.gmail.com>
 <20140321013313.GA58343@cskk.homeip.net>
Message-ID: <lggjcc$or$1@ger.gmane.org>


"Cameron Simpson" <cs at zip.com.au> wrote in message 
news:20140321013313.GA58343 at cskk.homeip.net...
>
> Someone intending to clone the project and develop will probably
> want the whole repository; as Gregory says - they can then easily
> push/pull with others.
>
> For Frank, the size of the repo is not the size of the bare code *
> number of changesets. There are many diff-level steps in there,
> making for a much smaller size. And code is small; really really
> small.
>

Ok, I think I've got it.

To make the software available to anyone who just wants to run a stable 
version, copy the working directory of the 'major release' repository to a 
directory of its own, without the .hg stuff, and make it available for 
download.

For everyone else, just make the full repository available, and don't worry 
about the size.

'Everyone else' would include those wishing to collaborate on the project, 
and those who just wish to keep up to date with the latest updates.

Actually my concern was not the 'size' of the full repository, but the 
prospect of wading through thousands of changesets most of which are ancient 
history. However, I assume that the experienced user will adopt habits such 
as 'hg log tip:-10' to review the last 10 changesets, so it should not be a 
problem.

Thanks, all

Frank





From rosuav at gmail.com  Fri Mar 21 01:47:07 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 16:47:07 +1100
Subject: Question about Source Control
In-Reply-To: <lggjcc$or$1@ger.gmane.org>
References: <CAPTjJmq4MkGjOY_en-v=hA=3oJ1sef_uF8BbQ9nm6r8nPMwTgA@mail.gmail.com>
 <20140321013313.GA58343@cskk.homeip.net>
 <lggjcc$or$1@ger.gmane.org>
Message-ID: <CAPTjJmpuYEo0R+v3OTt3un0SH-r5LW2SaXWwpkCu6p6MWpu44A@mail.gmail.com>

On Fri, Mar 21, 2014 at 4:40 PM, Frank Millman <frank at chagford.com> wrote:
> To make the software available to anyone who just wants to run a stable
> version, copy the working directory of the 'major release' repository to a
> directory of its own, without the .hg stuff, and make it available for
> download.
>
> For everyone else, just make the full repository available, and don't worry
> about the size.
>
> 'Everyone else' would include those wishing to collaborate on the project,
> and those who just wish to keep up to date with the latest updates.

That sounds about right. I have a number of people who use Gypsum
without any interest in coding it, but cloning the git repo is still
the easiest way to (a) get the code, and (b) pull changes later. (It
helps that I created a command in the program that pulls changes and
then does an internal "update all" to apply those changes without
restarting the program.)

> Actually my concern was not the 'size' of the full repository, but the
> prospect of wading through thousands of changesets most of which are ancient
> history. However, I assume that the experienced user will adopt habits such
> as 'hg log tip:-10' to review the last 10 changesets, so it should not be a
> problem.

Anyone who actually cares about the changes will need to know how to
use the version control system you're using. They can then use "hg
view" or "hg log" or whatever to see just what they care about;
personally, I'd just use "hg log|less", which is like "git log" - when
you're done reading recent stuff, hit q and get out of there.

ChrisA


From marko at pacujo.net  Fri Mar 21 01:49:54 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 21 Mar 2014 07:49:54 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
 <87pplgoac6.fsf@elektro.pacujo.net>
 <mailman.8322.1395351136.18130.python-list@python.org>
 <8738icmrw4.fsf@elektro.pacujo.net>
 <mailman.8330.1395357989.18130.python-list@python.org>
Message-ID: <87txasksn1.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> go for the lowest common denominator:
>
> print("some single string")
>
> which works happily in all versions of Python.

Whenever I have used "print" in my code, it has been with a >>
redirection.


Marko


From rosuav at gmail.com  Fri Mar 21 01:54:26 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 21 Mar 2014 16:54:26 +1100
Subject: running python 2 vs 3
In-Reply-To: <87txasksn1.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
 <87pplgoac6.fsf@elektro.pacujo.net>
 <mailman.8322.1395351136.18130.python-list@python.org>
 <8738icmrw4.fsf@elektro.pacujo.net>
 <mailman.8330.1395357989.18130.python-list@python.org>
 <87txasksn1.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmrYVisxf2XHy7YKCznr8Mrjm98rqV6GPLaF7Chz8w5AOA@mail.gmail.com>

On Fri, Mar 21, 2014 at 4:49 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> go for the lowest common denominator:
>>
>> print("some single string")
>>
>> which works happily in all versions of Python.
>
> Whenever I have used "print" in my code, it has been with a >>
> redirection.

Then you're probably not using "sys.stdout.write" but some other file
object's write method.

Also, I find it highly unusual that you never use print in its most
basic and intended form.

ChrisA


From cs at zip.com.au  Fri Mar 21 02:00:50 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Fri, 21 Mar 2014 17:00:50 +1100
Subject: Question about Source Control
In-Reply-To: <lggjcc$or$1@ger.gmane.org>
References: <lggjcc$or$1@ger.gmane.org>
Message-ID: <20140321060050.GA87434@cskk.homeip.net>

On 21Mar2014 07:40, Frank Millman <frank at chagford.com> wrote:
> "Cameron Simpson" <cs at zip.com.au> wrote in message 
> news:20140321013313.GA58343 at cskk.homeip.net...
> > Someone intending to clone the project and develop will probably
> > want the whole repository; as Gregory says - they can then easily
> > push/pull with others.
> >
> > For Frank, the size of the repo is not the size of the bare code *
> > number of changesets. There are many diff-level steps in there,
> > making for a much smaller size. And code is small; really really
> > small.
> 
> Ok, I think I've got it.
> 
> To make the software available to anyone who just wants to run a stable 
> version, copy the working directory of the 'major release' repository to a 
> directory of its own, without the .hg stuff, and make it available for 
> download.

See "hg archive". It does exactly that for you. Run "hg help archive".
It will also make tarballs and other archive formats.

> For everyone else, just make the full repository available, and don't worry 
> about the size.
> 
> 'Everyone else' would include those wishing to collaborate on the project, 
> and those who just wish to keep up to date with the latest updates.
> 
> Actually my concern was not the 'size' of the full repository, but the 
> prospect of wading through thousands of changesets most of which are ancient 
> history. However, I assume that the experienced user will adopt habits such 
> as 'hg log tip:-10' to review the last 10 changesets, so it should not be a 
> problem.

Yep.

Also see "hg blame". (Run "hg help blame" for usage info.)

For example, inside my "hg/css" repository I can say:

  hg blame bin/set-x

and the output goes:

    [hg/css]fleet*> hg blame bin/set-x
     2186: #!/bin/sh
    11359: #
    11359: # Trace execution of a command.

and so on the the end of the file. That tells me when those lines
of the file were last modified (by local changeset number). You
could pick a line in the file that you're interested in and look
at log entries for that.

For example, taking "11359" from the above listing, I can go:

    [hg/css]fleet*> hg log -r 11359
    changeset:   11359:136315cc8ec5
    user:        Cameron Simpson <cs at zip.com.au>
    date:        Wed Mar 05 10:37:09 2014 +1100
    files:       bin/set-x
    description:
    set-x: add --date option to timestamp command start and end, upgrade option parsing logic

That is for the whole changeset, but it happens to affect just that one
file.

Alternatively, although there may be many many changes, for some
files it is not so noisy. You might go:

    hg log bin/set-x

to show only changes involving that particular file.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

The aim of AI is to make computers act like the ones in the movies.
        - Graham Mann


From marko at pacujo.net  Fri Mar 21 02:08:42 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 21 Mar 2014 08:08:42 +0200
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
 <87pplgoac6.fsf@elektro.pacujo.net>
 <mailman.8322.1395351136.18130.python-list@python.org>
 <8738icmrw4.fsf@elektro.pacujo.net>
 <mailman.8330.1395357989.18130.python-list@python.org>
 <87txasksn1.fsf@elektro.pacujo.net>
 <mailman.8347.1395381598.18130.python-list@python.org>
Message-ID: <87mwgkkrrp.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Then you're probably not using "sys.stdout.write" but some other file
> object's write method.

Correct, sys.stderr.write would have been a more accurate choice.

> Also, I find it highly unusual that you never use print in its most
> basic and intended form.

Printing to the stdout (hardcoded) is a relatively rare need. Mostly,
I've used "print" for diagnostic messages, and whenever I've had to
create actual output, I've parameterized the target object.


Marko


From rustompmody at gmail.com  Fri Mar 21 02:51:17 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 20 Mar 2014 23:51:17 -0700 (PDT)
Subject: running python 2 vs 3
In-Reply-To: <87mwgkkrrp.fsf@elektro.pacujo.net>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net>
 <532B4750.2090006@yahoo.com> <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8316.1395347407.18130.python-list@python.org>
 <8738icppoe.fsf@elektro.pacujo.net>
 <mailman.8320.1395348816.18130.python-list@python.org>
 <87pplgoac6.fsf@elektro.pacujo.net>
 <mailman.8322.1395351136.18130.python-list@python.org>
 <8738icmrw4.fsf@elektro.pacujo.net>
 <mailman.8330.1395357989.18130.python-list@python.org>
 <87txasksn1.fsf@elektro.pacujo.net>
 <mailman.8347.1395381598.18130.python-list@python.org>
 <87mwgkkrrp.fsf@elektro.pacujo.net>
Message-ID: <3bf8380e-a62e-4961-bcde-9afdd33cfe30@googlegroups.com>

On Friday, March 21, 2014 11:38:42 AM UTC+5:30, Marko Rauhamaa wrote:
> Chris Angelico :

> > Then you're probably not using "sys.stdout.write" but some other file
> > object's write method.

> Correct, sys.stderr.write would have been a more accurate choice.

> > Also, I find it highly unusual that you never use print in its most
> > basic and intended form.

> Printing to the stdout (hardcoded) is a relatively rare need. Mostly,
> I've used "print" for diagnostic messages, and whenever I've had to
> create actual output, I've parameterized the target object.

Hear Hear!
Ive no opinion on whether python 2 or 3 print is better.

However I believe that people trying to help noobs would be actually
more helpful if they indicated that using prints all over code is not kosher.

Then whats the use/sense of print?? Debugging...


From 401anil at gmail.com  Fri Mar 21 04:14:48 2014
From: 401anil at gmail.com (Anil Kumar A)
Date: Fri, 21 Mar 2014 01:14:48 -0700 (PDT)
Subject: Need help in Python automation
Message-ID: <277bdaaa-b05e-4fbe-a2e2-4c142a207ea6@googlegroups.com>

-------------------------------------------------------------
Hi All,

I work for an ISP. Currently we bought few switches and routers. Python is available in that switches. So I would like to write some scipts which I can run inside switch. 

I tried module 'os, system', but It is not executing the commands in operational and configurational mode. Those modes' prompts are '*>' and '*#'. 

Can somebody suggest me, if there is any module which I can use to execute commands inside a switch.

I don't want to use 'socket' module as I am not connecting the box and executing commands. I am running the script inside switch.

Please give some clue to start my automation.

Thanks!

Anil Kumar A

-------------------------------------------------------------


From breamoreboy at yahoo.co.uk  Fri Mar 21 05:40:40 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Fri, 21 Mar 2014 09:40:40 +0000
Subject: running python 2 vs 3
In-Reply-To: <CAPTjJmo+ASg+7ixYc57u7MNS8pnhtZxbDV45pQK24LYFcT-iVw@mail.gmail.com>
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
 <mailman.8319.1395348268.18130.python-list@python.org>
 <87txasoaqi.fsf@elektro.pacujo.net>
 <532b8f0d$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-C004D1.21064220032014@news.panix.com>
 <CAPTjJmo+ASg+7ixYc57u7MNS8pnhtZxbDV45pQK24LYFcT-iVw@mail.gmail.com>
Message-ID: <lgh1ee$m4u$1@ger.gmane.org>

On 21/03/2014 02:18, Chris Angelico wrote:
> On Fri, Mar 21, 2014 at 12:06 PM, Roy Smith <roy at panix.com> wrote:
>> In article <532b8f0d$0$29994$c3e8da3$5496439d at news.astraweb.com>,
>>   Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>>
>>> The rule of three applies here: anything you do in three different places
>>> ought to be managed by a function.
>>
>> I prefer the rule of two :-)
>
> The way I explain it is: Three is a rule of thumb. Sometimes it's
> blatantly obvious at two, and other times you need four or five
> similar pieces of code before you can see which part should become the
> function. If the code's absolutely identical and reasonably
> long/complex, then yes, two's all you need, but how often is that?
> Usually it's similar, rather than congruent... err I mean identical.
> That's where the third usage comes in. Or if it's maybe 2-3 lines,
> used in two places, it doesn't necessarily need to be a function.
> Again, a third usage is a strong hint that it should be broken out.
>
> The rule doesn't say that anything that *isn't* in three places yet
> should *not* be broken out. :)
>
> ChrisA
>

Everybody, and especially Antipodeans, knows that there is no rule 6 and 
by definition what rule 7 is :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From breamoreboy at yahoo.co.uk  Fri Mar 21 05:50:20 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Fri, 21 Mar 2014 09:50:20 +0000
Subject: Python - Caeser Cipher Not Giving Right Output
In-Reply-To: <32c74575-6387-45d5-ab8b-b414c035c98a@googlegroups.com>
References: <7eee0f2b-0d5f-409e-ae4e-8c9c1af31d74@googlegroups.com>
 <mailman.8341.1395371543.18130.python-list@python.org>
 <bda05813-d186-41ea-a40d-5d36f90a8fed@googlegroups.com>
 <532bb8f3$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <32c74575-6387-45d5-ab8b-b414c035c98a@googlegroups.com>
Message-ID: <lgh20i$3mv$1@ger.gmane.org>

On 21/03/2014 04:23, dtran.ru at gmail.com wrote:

Would you please access this list via 
https://mail.python.org/mailman/listinfo/python-list or read and action 
this https://wiki.python.org/moin/GoogleGroupsPython to prevent us 
seeing double line spacing and single line paragraphs, thanks.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From sadzak at gmail.com  Fri Mar 21 06:22:37 2014
From: sadzak at gmail.com (Adnan Sadzak)
Date: Fri, 21 Mar 2014 11:22:37 +0100
Subject: Need help in Python automation
In-Reply-To: <277bdaaa-b05e-4fbe-a2e2-4c142a207ea6@googlegroups.com>
References: <277bdaaa-b05e-4fbe-a2e2-4c142a207ea6@googlegroups.com>
Message-ID: <CAG6E59Uqs=YBkye5km78v3ApXSkz84iAqQ6aRga1sRaYR3oahA@mail.gmail.com>

Hi,
there should be manufacturer documentation or API. What switch do You use?
Any other info?

Cheers,
Adnan


On Fri, Mar 21, 2014 at 9:14 AM, Anil Kumar A <401anil at gmail.com> wrote:

> -------------------------------------------------------------
> Hi All,
>
> I work for an ISP. Currently we bought few switches and routers. Python is
> available in that switches. So I would like to write some scipts which I
> can run inside switch.
>
> I tried module 'os, system', but It is not executing the commands in
> operational and configurational mode. Those modes' prompts are '*>' and
> '*#'.
>
> Can somebody suggest me, if there is any module which I can use to execute
> commands inside a switch.
>
> I don't want to use 'socket' module as I am not connecting the box and
> executing commands. I am running the script inside switch.
>
> Please give some clue to start my automation.
>
> Thanks!
>
> Anil Kumar A
>
> -------------------------------------------------------------
> --
> https://mail.python.org/mailman/listinfo/python-list
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-list/attachments/20140321/922ccbbd/attachment.html>

From fiensproto at gmail.com  Fri Mar 21 08:02:28 2014
From: fiensproto at gmail.com (fiensproto at gmail.com)
Date: Fri, 21 Mar 2014 05:02:28 -0700 (PDT)
Subject: CallBack function in C Libraries.
In-Reply-To: <op.xc1uldoj5079vu@gnudebeest>
References: <a9908cb7-3566-42a8-a468-8179ac1df7ab@googlegroups.com>
 <lgfucb$4q7$1@speranza.aioe.org>
 <e469fc0a-596c-40b6-8b27-751a4fe84d85@googlegroups.com>
 <op.xc1uldoj5079vu@gnudebeest>
Message-ID: <488fbd2c-1b99-482d-a282-f3f20defbc68@googlegroups.com>

> I'm afraid it doesn't help that GoogleGroups has badly mangled the  
> 
> formatting of your code.  I'm not quite sure what to suggest since it  
> 
> isn't one of the usual problems, but you might find reading  
> 
> https://wiki.python.org/moin/GoogleGroupsPython helpful.  It will  
> 
> certainly help with the double-spacing in your quote above.

> Rhodri James *-* Wildebeest Herder to the Masses


Yep, Many thanks for help....
Hum, i have find the solution, it was in "CallBack function" in help-doc.

=> 

#file fpgui-test.py
from ctypes import*

def TheProc():
    fpgui.fpgFormWindowTitle(0, 'Boum')
    return 0 

def TheProcBut0():
    fpgui.fpgButtonSetText(0,0, 'Boum also')
    return 0 
    
def TheProcBut1():
    fpgui.fpgButtonSetText(0,1, 'Boum too')
    return 0 
 
CMPFUNC = CFUNCTYPE(c_int)

TheProcF = CMPFUNC(TheProc)
TheProcB0 = CMPFUNC(TheProcBut0)
TheProcB1 = CMPFUNC(TheProcBut1)

fpgui = cdll.LoadLibrary("fpgui-32.dll")

fpgui.fpgInitialize()
fpgui.fpgSetStyle('Demo Style')
fpgui.fpgFormCreate(0, -1)
fpgui.fpgFormSetPosition(0, 300,100,400,200)
fpgui.fpgFormWindowTitle(0, 'Hello world!')

fpgui.fpgFormOnClick(0,TheProcF) 

fpgui.fpgButtonCreate(0,0,-1) ;
fpgui.fpgButtonSetPosition(0,0, 15, 10 , 150 , 40)
fpgui.fpgButtonSetText(0,0, 'BUTTON1')
fpgui.fpgButtonOnClick(0,0,TheProcB0) 

fpgui.fpgButtonCreate(0,1,-1) ;
fpgui.fpgButtonSetPosition(0,1, 15, 70 , 150, 40)
fpgui.fpgButtonSetText(0,1, 'Clickme')
fpgui.fpgButtonOnClick(0,1,TheProcB1)

fpgui.fpgFormShow(0)
fpgui.fpgRun()


From alister.nospam.ware at ntlworld.com  Fri Mar 21 08:09:13 2014
From: alister.nospam.ware at ntlworld.com (alister)
Date: Fri, 21 Mar 2014 12:09:13 GMT
Subject: running python 2 vs 3
References: <bp0e1eF613oU1@mid.individual.net>
 <87ob10nbeh.fsf@elektro.pacujo.net> <532B4750.2090006@yahoo.com>
 <87eh1wpr96.fsf@elektro.pacujo.net>
 <mailman.8313.1395346968.18130.python-list@python.org>
 <87a9ckpq7y.fsf@elektro.pacujo.net>
 <mailman.8319.1395348268.18130.python-list@python.org>
 <87txasoaqi.fsf@elektro.pacujo.net>
 <532b8f0d$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-C004D1.21064220032014@news.panix.com>
 <CAPTjJmo+ASg+7ixYc57u7MNS8pnhtZxbDV45pQK24LYFcT-iVw@mail.gmail.com>
 <mailman.8349.1395394859.18130.python-list@python.org>
Message-ID: <JZVWu.151296$Gq7.56995@fx29.am4>

On Fri, 21 Mar 2014 09:40:40 +0000, Mark Lawrence wrote:

> On 21/03/2014 02:18, Chris Angelico wrote:
>> On Fri, Mar 21, 2014 at 12:06 PM, Roy Smith <roy at panix.com> wrote:
>>> In article <532b8f0d$0$29994$c3e8da3$5496439d at news.astraweb.com>,
>>>   Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>>>
>>>> The rule of three applies here: anything you do in three different
>>>> places ought to be managed by a function.
>>>
>>> I prefer the rule of two :-)
>>
>> The way I explain it is: Three is a rule of thumb. Sometimes it's
>> blatantly obvious at two, and other times you need four or five similar
>> pieces of code before you can see which part should become the
>> function. If the code's absolutely identical and reasonably
>> long/complex, then yes, two's all you need, but how often is that?
>> Usually it's similar, rather than congruent... err I mean identical.
>> That's where the third usage comes in. Or if it's maybe 2-3 lines, used
>> in two places, it doesn't necessarily need to be a function. Again, a
>> third usage is a strong hint that it should be broken out.
>>
>> The rule doesn't say that anything that *isn't* in three places yet
>> should *not* be broken out. :)
>>
>> ChrisA
>>
>>
> Everybody, and especially Antipodeans, knows that there is no rule 6 and
> by definition what rule 7 is :)

Im sticking with rule 4


From roy at panix.com  Fri Mar 21 08:23:31 2014
From: roy at panix.com (Roy Smith)
Date: Fri, 21 Mar 2014 08:23:31 -0400
Subject: Question about Source Control
References: <lggjcc$or$1@ger.gmane.org>
 <mailman.8348.1395381664.18130.python-list@python.org>
Message-ID: <roy-B841BA.08233121032014@news.panix.com>

In article <mailman.8348.1395381664.18130.python-list at python.org>,
 Cameron Simpson <cs at zip.com.au> wrote:

>   hg blame bin/set-x
> 
> and the output goes:
> 
>     [hg/css]fleet*> hg blame bin/set-x
>      2186: #!/bin/sh
>     11359: #
>     11359: # Trace execution of a command.

There's two things hg blame doesn't do which would be useful.

First, the trivial one.  I don't want lines annotated by change number, 
I want them annotated by the name of the person who checked it in.  But, 
I'm sure that can be easily fixed with some simple post-processing 
filter, so it really falls into the bucket of "minor annoyances".

The hard thing is I don't really want to know which change most recently 
touched the line of text.  I want to know who really wrote it.  It would 
be wonderful if hg were smart enough to be able to back-track through 
the change history and ignore trivial changes like whitespace, 
refactoring a function out of one file into another, etc.  That's the 
real meat and potatoes of "blame".  I want to know who I need to hit 
over the head with a clue-by-four once I fix a bug.


From skip at pobox.com  Fri Mar 21 09:22:28 2014
From: skip at pobox.com (Skip Montanaro)
Date: Fri, 21 Mar 2014 08:22:28 -0500
Subject: Github down?
Message-ID: <CANc-5Uxf71ZEOtqHzYbgB3Gg5jwQM-=oYefdKL2bq=En+P1jTQ@mail.gmail.com>

Anybody else having trouble getting to Github? I'm trying to get to
the pythondotorg issue tracker:

https://github.com/python/pythondotorg/issues

Thx,

Skip


From larry.martell at gmail.com  Fri Mar 21 09:24:44 2014
From: larry.martell at gmail.com (Larry Martell)
Date: Fri, 21 Mar 2014 09:24:44 -0400
Subject: Github down?
In-Reply-To: <CANc-5Uxf71ZEOtqHzYbgB3Gg5jwQM-=oYefdKL2bq=En+P1jTQ@mail.gmail.com>
References: <CANc-5Uxf71ZEOtqHzYbgB3Gg5jwQM-=oYefdKL2bq=En+P1jTQ@mail.gmail.com>
Message-ID: <CACwCsY7-mVjdvGdhN5VDohp2Sjujo3t=xUkN6ZwhXuFp1A9YdQ@mail.gmail.com>

On Fri, Mar 21, 2014 at 9:22 AM, Skip Montanaro <skip at pobox.com> wrote:
> Anybody else having trouble getting to Github? I'm trying to get to
> the pythondotorg issue tracker:
>
> https://github.com/python/pythondotorg/issues

They post the status at:

https://twitter.com/githubstatus

As of 10 minutes ago it was down.


From chip9munk at gmail.com  Fri Mar 21 09:29:56 2014
From: chip9munk at gmail.com (chip9munk at gmail.com)
Date: Fri, 21 Mar 2014 06:29:56 -0700 (PDT)
Subject: csv read _csv.Error: line contains NULL byte
Message-ID: <22aeefa3-cf82-457c-ab85-6f0366ff7b4e@googlegroups.com>

Hi all!

I am reading from a huge csv file (> 20 Gb), so I have to read line by line:

for i, row in enumerate(input_reader):
      #  and I do something on each row

Everything works fine until i get to a row with some strange symbols "0I`00?^"
at that point I get an error: _csv.Error: line contains NULL byte

How can i skip such row and continue going, or "decipher" it in some way?

I have tried :
csvFile = open(input_file_path, 'rb')
csvFile = open(input_file_path, 'rU')
csvFile = open(input_file_path, 'r')

and nothing works.

if I do:

try:
    for i, row in enumerate(input_reader):
      #  and I do something on each row
except Exception:
    sys.exc_clear() 

i simply stop an that line. I would like to skip it and move on.

Please help!

Best,

Chip Munk


From mail at timgolden.me.uk  Fri Mar 21 09:39:37 2014
From: mail at timgolden.me.uk (Tim Golden)
Date: Fri, 21 Mar 2014 13:39:37 +0000
Subject: csv read _csv.Error: line contains NULL byte
In-Reply-To: <22aeefa3-cf82-457c-ab85-6f0366ff7b4e@googlegroups.com>
References: <22aeefa3-cf82-457c-ab85-6f0366ff7b4e@googlegroups.com>
Message-ID: <532C4119.2030507@timgolden.me.uk>

On 21/03/2014 13:29, chip9munk at gmail.com wrote:
> Hi all!
> 
> I am reading from a huge csv file (> 20 Gb), so I have to read line by line:
> 
> for i, row in enumerate(input_reader):
>       #  and I do something on each row
> 
> Everything works fine until i get to a row with some strange symbols "0I`00?^"
> at that point I get an error: _csv.Error: line contains NULL byte
> 
> How can i skip such row and continue going, or "decipher" it in some way?

Well you have several options:

Without disturbing your existing code too much, you could wrap the
input_reader in a generator which skips malformed lines. That would look
something like this:

def unfussy_reader(reader):
    while True:
        try:
            yield next(reader)
        except csv.Error:
            # log the problem or whatever
            continue


If you knew what to do with the malformed data, you strip it out and
carry on. Whatever works best for you.

Alternatively you could subclass the standard Reader and do something
equivalent to the above in the __next__ method.

TJG




From skip at pobox.com  Fri Mar 21 09:48:38 2014
From: skip at pobox.com (Skip Montanaro)
Date: Fri, 21 Mar 2014 08:48:38 -0500
Subject: Github down?
In-Reply-To: <CACwCsY7-mVjdvGdhN5VDohp2Sjujo3t=xUkN6ZwhXuFp1A9YdQ@mail.gmail.com>
References: <CANc-5Uxf71ZEOtqHzYbgB3Gg5jwQM-=oYefdKL2bq=En+P1jTQ@mail.gmail.com>
 <CACwCsY7-mVjdvGdhN5VDohp2Sjujo3t=xUkN6ZwhXuFp1A9YdQ@mail.gmail.com>
Message-ID: <CANc-5Uw0r=CNvj1Q7dfzqLGDp_f+3dZwiQtaKsQXjhbK2HnnZQ@mail.gmail.com>

On Fri, Mar 21, 2014 at 8:24 AM, Larry Martell <larry.martell at gmail.com> wrote:
> https://twitter.com/githubstatus

Thanks for the pointer. I'm an old fart and don't use social media
much (in fact, just closed my FB account a couple days ago). Does that
mean I'm a curmudgeon? :-)

Skip


From kwpolska at gmail.com  Fri Mar 21 09:51:54 2014
From: kwpolska at gmail.com (=?UTF-8?B?Q2hyaXMg4oCcS3dwb2xza2HigJ0gV2Fycmljaw==?=)
Date: Fri, 21 Mar 2014 14:51:54 +0100
Subject: Github down?
In-Reply-To: <CANc-5Uw0r=CNvj1Q7dfzqLGDp_f+3dZwiQtaKsQXjhbK2HnnZQ@mail.gmail.com>
References: <CANc-5Uxf71ZEOtqHzYbgB3Gg5jwQM-=oYefdKL2bq=En+P1jTQ@mail.gmail.com>
 <CACwCsY7-mVjdvGdhN5VDohp2Sjujo3t=xUkN6ZwhXuFp1A9YdQ@mail.gmail.com>
 <CANc-5Uw0r=CNvj1Q7dfzqLGDp_f+3dZwiQtaKsQXjhbK2HnnZQ@mail.gmail.com>
Message-ID: <CAMw+j7LUHUDGQ5CftQa_X8s=nixPq+EfdgvKkn+V0xmB_EFXVA@mail.gmail.com>

On Fri, Mar 21, 2014 at 2:48 PM, Skip Montanaro <skip at pobox.com> wrote:
> On Fri, Mar 21, 2014 at 8:24 AM, Larry Martell <larry.martell at gmail.com> wrote:
>> https://twitter.com/githubstatus
>
> Thanks for the pointer. I'm an old fart and don't use social media
> much (in fact, just closed my FB account a couple days ago). Does that
> mean I'm a curmudgeon? :-)

If you dislike social media (or prefer a nice website with graphs and
such), then go there:

https://status.github.com/

(though GitHub could qualify as social media for some?)

-- 
Chris ?Kwpolska? Warrick <http://kwpolska.tk>
PGP: 5EAAEA16
stop html mail | always bottom-post | only UTF-8 makes sense


From larry.martell at gmail.com  Fri Mar 21 09:56:16 2014
From: larry.martell at gmail.com (Larry Martell)
Date: Fri, 21 Mar 2014 09:56:16 -0400
Subject: Github down?
In-Reply-To: <CANc-5Uw0r=CNvj1Q7dfzqLGDp_f+3dZwiQtaKsQXjhbK2HnnZQ@mail.gmail.com>
References: <CANc-5Uxf71ZEOtqHzYbgB3Gg5jwQM-=oYefdKL2bq=En+P1jTQ@mail.gmail.com>
 <CACwCsY7-mVjdvGdhN5VDohp2Sjujo3t=xUkN6ZwhXuFp1A9YdQ@mail.gmail.com>
 <CANc-5Uw0r=CNvj1Q7dfzqLGDp_f+3dZwiQtaKsQXjhbK2HnnZQ@mail.gmail.com>
Message-ID: <CACwCsY7tN3uQj0q0xB4afETxWdwNbAH0qn4-HYb5aZCQ6aBFFQ@mail.gmail.com>

On Fri, Mar 21, 2014 at 9:48 AM, Skip Montanaro <skip at pobox.com> wrote:
> On Fri, Mar 21, 2014 at 8:24 AM, Larry Martell <larry.martell at gmail.com> wrote:
>> https://twitter.com/githubstatus
>
> Thanks for the pointer. I'm an old fart and don't use social media
> much (in fact, just closed my FB account a couple days ago). Does that
> mean I'm a curmudgeon? :-)

I don't use FB or twitter, but I do use Linkedin. But going to
https://twitter.com/githubstatus is not using twitter, it's just going
to a web site.


From info at wingware.com  Fri Mar 21 10:27:11 2014
From: info at wingware.com (Wingware)
Date: Fri, 21 Mar 2014 10:27:11 -0400
Subject: ANN:  Wing IDE 5.0.4 released
Message-ID: <532C4C3F.3010409@wingware.com>

Hi,

Wingware has released version 5.0.4 of Wing IDE, our cross-platform 
integrated
development environment for the Python programming language.

Wing IDE includes a professional quality code editor with vi, emacs, 
visual studio,
and other key bindings, auto-completion, call tips, goto-definition, 
find uses, refactoring,
context-aware auto-editing, a powerful graphical debugger, version 
control, unit testing,
search, and many other features.  For details see http://wingware.com/

Changes in this minor release include:

* Support for Python 3.4 final release
* Improved Source Assistant renders PEP 287 docstrings and displays 
return value type
* Optional New Project dialog
* Improved integrated documentation display
* Improved PDF formatted documentation
* Support for recent git versions
* Fix environment used with named entry points and launch configurations
* Fix Debug Probe for Django templates
* Fix inline renaming of files in the Project tool
* Several optimizations
* About 40 other bug fixes

For details see http://wingware.com/pub/wingide/5.0.4/CHANGELOG.txt

A summary of new features in Wing 5:

* Redesigned GUI based on Qt and PySide
* Native GUI on OS X (and better overall OS-native look and feel)
* Tools and editors can be dragged around
* Toolbar and editor and Project context menus are configurable
* Optional mode that opens different sets of files in each editor split
* Sharable color palettes and syntax highlighting configurations
* Auto-editing is on by default (except some operations that have a 
learning curve)
* Named file sets
* Sharable launch configurations
* Named entry points
* More control over unit testing environment
* Lockable editor splits
* Initial preferences dialog for new users
* Support for Python 3.4
* Support for Django 1.6
* Support for matplotlib on Anaconda and with MacOSX backend
* Improved Source Assistant with PEP 287 docstring rendering and return 
types
* Improved integrated and PDF documentation

For more information on what's new in Wing 5, see 
http://wingware.com/wingide/whatsnew

Free trial: http://wingware.com/wingide/trial
Downloads: http://wingware.com/downloads
Feature list: http://wingware.com/wingide/features
Sales: http://wingware.com/store/purchase
Upgrades: https://wingware.com/store/upgrade

Questions?  Don't hesitate to email us at support at wingware.com.

Thanks,

-- 

Stephan Deibel
Wingware | Python IDE

The Intelligent Development Environment for Python Programmers

wingware.com



From breamoreboy at yahoo.co.uk  Fri Mar 21 10:38:42 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Fri, 21 Mar 2014 14:38:42 +0000
Subject: Github down?
In-Reply-To: <CANc-5Uxf71ZEOtqHzYbgB3Gg5jwQM-=oYefdKL2bq=En+P1jTQ@mail.gmail.com>
References: <CANc-5Uxf71ZEOtqHzYbgB3Gg5jwQM-=oYefdKL2bq=En+P1jTQ@mail.gmail.com>
Message-ID: <lghit8$idu$1@ger.gmane.org>

On 21/03/2014 13:22, Skip Montanaro wrote:
> Anybody else having trouble getting to Github? I'm trying to get to
> the pythondotorg issue tracker:
>
> https://github.com/python/pythondotorg/issues
>
> Thx,
>
> Skip
>

http://www.downforeveryoneorjustme.com/

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From chip9munk at gmail.com  Fri Mar 21 10:46:00 2014
From: chip9munk at gmail.com (chip9munk at gmail.com)
Date: Fri, 21 Mar 2014 07:46:00 -0700 (PDT)
Subject: csv read _csv.Error: line contains NULL byte
In-Reply-To: <mailman.8354.1395409181.18130.python-list@python.org>
References: <22aeefa3-cf82-457c-ab85-6f0366ff7b4e@googlegroups.com>
 <mailman.8354.1395409181.18130.python-list@python.org>
Message-ID: <fefcec40-3bd9-4a94-9ae8-4f214fce2302@googlegroups.com>

On Friday, March 21, 2014 2:39:37 PM UTC+1, Tim Golden wrote:

> Without disturbing your existing code too much, you could wrap the
> 
> input_reader in a generator which skips malformed lines. That would look
> 
> something like this:
> 
> 
> 
> def unfussy_reader(reader):
> 
>     while True:
> 
>         try:
> 
>             yield next(reader)
> 
>         except csv.Error:
> 
>             # log the problem or whatever
> 
>             continue


I am sorry I do not understand how to get to each row in this way.

Please could you explain also this:
If I define this function, 
how do I change my for loop to get each row?

Thanks!


From chip9munk at gmail.com  Fri Mar 21 10:59:13 2014
From: chip9munk at gmail.com (chip9munk at gmail.com)
Date: Fri, 21 Mar 2014 07:59:13 -0700 (PDT)
Subject: csv read _csv.Error: line contains NULL byte
In-Reply-To: <fefcec40-3bd9-4a94-9ae8-4f214fce2302@googlegroups.com>
References: <22aeefa3-cf82-457c-ab85-6f0366ff7b4e@googlegroups.com>
 <mailman.8354.1395409181.18130.python-list@python.org>
 <fefcec40-3bd9-4a94-9ae8-4f214fce2302@googlegroups.com>
Message-ID: <c66fbee9-d585-4d0d-98be-e925f2cfef5f@googlegroups.com>

Ok, I have figured it out:

for i, row in enumerate(unfussy_reader(input_reader): 
      #  and I do something on each row 

Sorry, it is my first "face to face" with generators!

Thank you very much!

Best,
Chip Munk


From mail at timgolden.me.uk  Fri Mar 21 10:59:01 2014
From: mail at timgolden.me.uk (Tim Golden)
Date: Fri, 21 Mar 2014 14:59:01 +0000
Subject: csv read _csv.Error: line contains NULL byte
In-Reply-To: <fefcec40-3bd9-4a94-9ae8-4f214fce2302@googlegroups.com>
References: <22aeefa3-cf82-457c-ab85-6f0366ff7b4e@googlegroups.com>
 <mailman.8354.1395409181.18130.python-list@python.org>
 <fefcec40-3bd9-4a94-9ae8-4f214fce2302@googlegroups.com>
Message-ID: <532C53B5.9020000@timgolden.me.uk>

On 21/03/2014 14:46, chip9munk at gmail.com wrote:
> I am sorry I do not understand how to get to each row in this way.
> 
> Please could you explain also this:
> If I define this function, 
> how do I change my for loop to get each row?

Does this help?

<code>
#!python3
import csv

def unfussy_reader(csv_reader):
    while True:
        try:
            yield next(csv_reader)
        except csv.Error:
            # log the problem or whatever
            print("Problem with some row")
            continue

if __name__ == '__main__':
    #
    # Generate malformed csv file for
    # demonstration purposes
    #
    with open("temp.csv", "w") as fout:
        fout.write("abc,def\nghi\x00,klm\n123,456")

    #
    # Open the malformed file for reading, fire up a
    # conventional CSV reader over it, wrap that reader
    # in our "unfussy" generator and enumerate over that
    # generator.
    #
    with open("temp.csv") as fin:
        reader = unfussy_reader(csv.reader(fin))
        for n, row in enumerate(reader):
            print(n, "=>", row)


</code>


TJG


From breamoreboy at yahoo.co.uk  Fri Mar 21 11:15:02 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Fri, 21 Mar 2014 15:15:02 +0000
Subject: csv read _csv.Error: line contains NULL byte
In-Reply-To: <fefcec40-3bd9-4a94-9ae8-4f214fce2302@googlegroups.com>
References: <22aeefa3-cf82-457c-ab85-6f0366ff7b4e@googlegroups.com>
 <mailman.8354.1395409181.18130.python-list@python.org>
 <fefcec40-3bd9-4a94-9ae8-4f214fce2302@googlegroups.com>
Message-ID: <lghl1c$l6b$1@ger.gmane.org>

On 21/03/2014 14:46, chip9munk at gmail.com wrote:
> On Friday, March 21, 2014 2:39:37 PM UTC+1, Tim Golden wrote:
>
>> Without disturbing your existing code too much, you could wrap the
>>
>> input_reader in a generator which skips malformed lines. That would look
>>
>> something like this:
>>
>>
>>
>> def unfussy_reader(reader):
>>
>>      while True:
>>
>>          try:
>>
>>              yield next(reader)
>>
>>          except csv.Error:
>>
>>              # log the problem or whatever
>>
>>              continue
>
>
> I am sorry I do not understand how to get to each row in this way.
>
> Please could you explain also this:
> If I define this function,
> how do I change my for loop to get each row?
>
> Thanks!
>

I'm pleased to see that you have answers.  In return would you either 
use the mailing list 
https://mail.python.org/mailman/listinfo/python-list or read and action 
this https://wiki.python.org/moin/GoogleGroupsPython to prevent us 
seeing double line spacing and single line paragraphs, thanks.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From antonyjoseph89 at gmail.com  Fri Mar 21 11:28:24 2014
From: antonyjoseph89 at gmail.com (Antony Joseph)
Date: Fri, 21 Mar 2014 20:58:24 +0530
Subject: Implement multiprocessing without inheriting parent file handle
Message-ID: <CAMTL9-fWZgxRnR-fYCZBtreazRSzk+yOWp_MKYKbRyK8t37Pcw@mail.gmail.com>

Hi all,

How can i implement multiprocessing without inherit file descriptors from
my parent process?

Please help me.

regards,
Antony
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From harrismh777 at gmail.com  Fri Mar 21 12:50:18 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 21 Mar 2014 11:50:18 -0500
Subject: CallBack function in C Libraries.
References: <a9908cb7-3566-42a8-a468-8179ac1df7ab@googlegroups.com>
 <lgfucb$4q7$1@speranza.aioe.org>
 <e469fc0a-596c-40b6-8b27-751a4fe84d85@googlegroups.com>
 <op.xc1uldoj5079vu@gnudebeest>
 <488fbd2c-1b99-482d-a282-f3f20defbc68@googlegroups.com>
Message-ID: <lghqk7$suf$1@speranza.aioe.org>

On 3/21/14 7:02 AM, fiensproto at gmail.com wrote:
> Yep, Many thanks for help....
> Hum, i have find the solution, it was in "CallBack function" in help-doc.

    No, it was not in the "CallBack function" in help-doc ...

>
> def TheProc():         <================== you moved c_int from here ...
>      fpgui.fpgFormWindowTitle(0, 'Boum')
>      return 0
>
{snip}
>
> CMPFUNC = CFUNCTYPE(c_int)   <============ and placed it here ...
>
> TheProcF = CMPFUNC(TheProc)    <========== so that when you called TheProc ...


... it wasn't "expecting" exactly one parameter. So, your python 
traceback no longer warns about the parameter 'mismatch' in the defined 
function  TheProc().

    I'm not picking on you, but this error was obvious; as was it's 
solution, so I'm just wondering ?

Cheers



From rosuav at gmail.com  Fri Mar 21 13:23:54 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 04:23:54 +1100
Subject: Question about Source Control
In-Reply-To: <roy-B841BA.08233121032014@news.panix.com>
References: <lggjcc$or$1@ger.gmane.org>
 <mailman.8348.1395381664.18130.python-list@python.org>
 <roy-B841BA.08233121032014@news.panix.com>
Message-ID: <CAPTjJmpBFCUfkkgcobAc=jMFObZDh4=7HEaFEHz=M0vbW1t28Q@mail.gmail.com>

On Fri, Mar 21, 2014 at 11:23 PM, Roy Smith <roy at panix.com> wrote:
> There's two things hg blame doesn't do which would be useful.
>
> First, the trivial one.  I don't want lines annotated by change number,
> I want them annotated by the name of the person who checked it in.  But,
> I'm sure that can be easily fixed with some simple post-processing
> filter, so it really falls into the bucket of "minor annoyances".
>
> The hard thing is I don't really want to know which change most recently
> touched the line of text.  I want to know who really wrote it.  It would
> be wonderful if hg were smart enough to be able to back-track through
> the change history and ignore trivial changes like whitespace,
> refactoring a function out of one file into another, etc.  That's the
> real meat and potatoes of "blame".  I want to know who I need to hit
> over the head with a clue-by-four once I fix a bug.

Hmm. 'git blame' can do both of those things, so I'd be very surprised
if 'hg blame' can't, at least with some extension(s). (The latter
feature is "git blame -w filename"; -w is a standard 'git diff' option
meaning "ignore whitespace".) But hey, if nothing else, you could
import your hg repo into git just to blame the file...

ChrisA


From harrismh777 at gmail.com  Fri Mar 21 13:25:36 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 21 Mar 2014 12:25:36 -0500
Subject: Implement multiprocessing without inheriting parent file handle
References: <mailman.8363.1395415712.18130.python-list@python.org>
Message-ID: <lghsmd$3as$1@speranza.aioe.org>

On 3/21/14 10:28 AM, Antony Joseph wrote:
> How can i implement multiprocessing without inherit file descriptors
> from my parent process?

I'll bite...

If what you mean by 'multiprocessing' is forking a process, to get a 
child process, which will then do some parallel processing for some 
reason, the answer is two-fold: 1) you can't, and 2) you might try using 
threads.  (there are other answers too)

When you fork a process the only differences between the child and the 
parent is 1) process number, and 2) one is the 'parent' and one is the 
'child'.  They are 'exact' copies of one another.

In socket daemons the parent always listens on a given port, then forks 
a child process to establish a secondary port(s) to handle the comm 
link;  at that point (instant) both the parent and the child ask a 
simple question, "Am I the parent?"  If so, the code goes back to 
listening... if not, the code (the child) establishes the necessary comm 
ports and handles the server request.  When finished the child notifies 
the parent and ends.

You can try parent/child arrangements (maybe use rpc, or shared memory 
segments for inter process comm), or you might try threads... which are 
a separate unit of execution (not a full process copy) but with access 
to the parent's memory.

Otherwise, you might want to tell the list some of the background of 
your difficulty, or put the difficulty in pythonic terms, or simply ask 
your python related question with as much simplified but complete detail 
as possible.

Is there a python question in there someplace?

marcus


From invalid at invalid.invalid  Fri Mar 21 13:37:24 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Fri, 21 Mar 2014 17:37:24 +0000 (UTC)
Subject: Implement multiprocessing without inheriting parent file handle
References: <mailman.8363.1395415712.18130.python-list@python.org>
Message-ID: <lghtck$oon$1@reader1.panix.com>

On 2014-03-21, Antony Joseph <antonyjoseph89 at gmail.com> wrote:

> How can i implement multiprocessing without inherit file descriptors from
> my parent process?

What one typically does if that is desired is to call fork() and then
in the child process close all open file descriptors before doing any
other processsing (such as exec()ing another program).

-- 
Grant Edwards               grant.b.edwards        Yow! My life is a patio
                                  at               of fun!
                              gmail.com            


From marko at pacujo.net  Fri Mar 21 13:42:19 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 21 Mar 2014 19:42:19 +0200
Subject: Implement multiprocessing without inheriting parent file handle
References: <mailman.8363.1395415712.18130.python-list@python.org>
Message-ID: <878us35tz8.fsf@elektro.pacujo.net>

Antony Joseph <antonyjoseph89 at gmail.com>:

> How can i implement multiprocessing without inherit file descriptors
> from my parent process?

Take a look at the subprocess module:

  <URL:
  http://docs.python.org/3/library/subprocess.html#popen-constructor>

It's got the optional close_fds parameter, which is True by default.

IOW, you don't need to do anything if you use subprocess.Popen() to
start your child process. Incidentally, that's the preferred way.


Marko


From jarausch at igpm.rwth-aachen.de  Fri Mar 21 13:48:49 2014
From: jarausch at igpm.rwth-aachen.de (Helmut Jarausch)
Date: 21 Mar 2014 17:48:49 GMT
Subject: Python3 - temporarily change the file encoding
Message-ID: <bp3cc1Fpgg4U1@mid.dfncis.de>

Hi,

my locale is en_US.iso88591

But now I'd like to process a restructuredtext file which is encoded in utf-8.

rst2html has

#!/usr/bin/python3.3

# $Id: rst2html.py 4564 2006-05-21 20:44:42Z wiemann $
# Author: David Goodger <goodger at python.org>
# Copyright: This module has been placed in the public domain.

"""
A minimal front end to the Docutils Publisher, producing HTML.
"""

try:
    import locale
    locale.setlocale(locale.LC_ALL, '')
except:
    pass

from docutils.core import publish_cmdline, default_description


description = ('Generates (X)HTML documents from standalone reStructuredText '
               'sources.  ' + default_description)

publish_cmdline(writer_name='html', description=description)

--------------

Even if I comment out the part containing 'import locale' the utf-8 encoding of my
rst-file is not recognized.

How can I change this so that rst2html use utf-8 when reading and writing files.
Of course, I don't want to change the docutils package for that.

Many thanks for a hint,
Helmut


From python.list at tim.thechases.com  Fri Mar 21 13:54:59 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Fri, 21 Mar 2014 12:54:59 -0500
Subject: Question about Source Control
In-Reply-To: <CAPTjJmpBFCUfkkgcobAc=jMFObZDh4=7HEaFEHz=M0vbW1t28Q@mail.gmail.com>
References: <lggjcc$or$1@ger.gmane.org>
 <mailman.8348.1395381664.18130.python-list@python.org>
 <roy-B841BA.08233121032014@news.panix.com>
 <CAPTjJmpBFCUfkkgcobAc=jMFObZDh4=7HEaFEHz=M0vbW1t28Q@mail.gmail.com>
Message-ID: <20140321125459.1247f5f5@bigbox.christie.dr>

On 2014-03-22 04:23, Chris Angelico wrote:
> > The hard thing is I don't really want to know which change most
> > recently touched the line of text.  I want to know who really
> > wrote it.  It would be wonderful if hg were smart enough to be
> > able to back-track through the change history and ignore trivial
> > changes like whitespace, refactoring a function out of one file
> > into another, etc.  That's the real meat and potatoes of
> > "blame".  I want to know who I need to hit over the head with a
> > clue-by-four once I fix a bug.  
> 
> Hmm. 'git blame' can do both of those things, so I'd be very
> surprised if 'hg blame' can't, at least with some extension(s).
> (The latter feature is "git blame -w filename"; -w is a standard
> 'git diff' option meaning "ignore whitespace".)

A quick "hg -help blame" suggests that it has options to at least
show the author and control the ignoring of whitespace, as well as
tweak other elements:

 -u --user                list the author (long with -v)
 -f --file                list the filename
 -d --date                list the date (short with -q)
 -n --number              list the revision number (default)
 -c --changeset           list the changeset
 -l --line-number         show line number at the first appearance
 -w --ignore-all-space    ignore white space when comparing lines
 -b --ignore-space-change ignore changes in the amount of white space
 -B --ignore-blank-lines  ignore changes whose lines are all blank

I don't see a "ignore refactoring", but I'd want to chase through
those more manually.


From python.list at tim.thechases.com  Fri Mar 21 13:59:53 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Fri, 21 Mar 2014 12:59:53 -0500
Subject: Question about Source Control
In-Reply-To: <20140321125459.1247f5f5@bigbox.christie.dr>
References: <lggjcc$or$1@ger.gmane.org>
 <mailman.8348.1395381664.18130.python-list@python.org>
 <roy-B841BA.08233121032014@news.panix.com>
 <CAPTjJmpBFCUfkkgcobAc=jMFObZDh4=7HEaFEHz=M0vbW1t28Q@mail.gmail.com>
 <20140321125459.1247f5f5@bigbox.christie.dr>
Message-ID: <20140321125953.6d8853d7@bigbox.christie.dr>

On 2014-03-21 12:54, Tim Chase wrote:
> A quick "hg -help blame"

Sigh. Accidentally hit <enter> when I meant to hit <backspace>
with <control> down.  That is, of course "hg help blame", formerly
written there as "hg -v help blame" and accidentally sent mid-edit.

-tkc




From harrismh777 at gmail.com  Fri Mar 21 14:16:30 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 21 Mar 2014 13:16:30 -0500
Subject: Implement multiprocessing without inheriting parent file handle
References: <mailman.8363.1395415712.18130.python-list@python.org>
 <878us35tz8.fsf@elektro.pacujo.net>
Message-ID: <lghvlr$bqs$1@speranza.aioe.org>

On 3/21/14 12:42 PM, Marko Rauhamaa wrote:
>    http://docs.python.org/3/library/subprocess.html#popen-constructor>

> It's got the optional close_fds parameter, which is True by default.

> IOW, you don't need to do anything if you use subprocess.Popen() to
> start your child process. Incidentally, that's the preferred way.

hi Marko, of course this depends on the environment; if unix-like, then 
yes, elif windows well, not so much...

There are caveats about stdin, stdout, and stderr;  as well, there are 
caveats about passing fds between the two. Well, Popen() is implemented 
on unix and windows differently, so there is some study needed here if 
code is going to be run in both environments.

marcus


From __peter__ at web.de  Fri Mar 21 14:38:53 2014
From: __peter__ at web.de (Peter Otten)
Date: Fri, 21 Mar 2014 19:38:53 +0100
Subject: Python3 - temporarily change the file encoding
References: <bp3cc1Fpgg4U1@mid.dfncis.de>
Message-ID: <lgi0ve$h5o$1@ger.gmane.org>

Helmut Jarausch wrote:

> Hi,
> 
> my locale is en_US.iso88591
> 
> But now I'd like to process a restructuredtext file which is encoded in
> utf-8.
> 
> rst2html has
> 
> #!/usr/bin/python3.3
> 
> # $Id: rst2html.py 4564 2006-05-21 20:44:42Z wiemann $
> # Author: David Goodger <goodger at python.org>
> # Copyright: This module has been placed in the public domain.
> 
> """
> A minimal front end to the Docutils Publisher, producing HTML.
> """
> 
> try:
>     import locale
>     locale.setlocale(locale.LC_ALL, '')
> except:
>     pass
> 
> from docutils.core import publish_cmdline, default_description
> 
> 
> description = ('Generates (X)HTML documents from standalone
> reStructuredText '
>                'sources.  ' + default_description)
> 
> publish_cmdline(writer_name='html', description=description)
> 
> --------------
> 
> Even if I comment out the part containing 'import locale' the utf-8
> encoding of my rst-file is not recognized.
> 
> How can I change this so that rst2html use utf-8 when reading and writing
> files. Of course, I don't want to change the docutils package for that.
> 
> Many thanks for a hint,

Hm, there is an --input-encoding option that should allow you to specify the 
encoding on the command line.



From vasudevram at gmail.com  Fri Mar 21 16:42:53 2014
From: vasudevram at gmail.com (vasudevram)
Date: Fri, 21 Mar 2014 13:42:53 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x in
 x] (to flatten a nested list)
Message-ID: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>


Hi list,

Can anyone - maybe one of the Python language core team, or someone with knowledge of the internals of Python - can explain why this code works, and whether the different occurrences of the name x in the expression, are in different scopes or not? :

x = [[1,2], [3,4], [5,6]]
    [x for x in x for x in x]

I saw this on a Hacker News thread about Python, and here is a post I wrote that gives more details about it, including relevant links, how I found that it can be extended to a triply-nested list, and my thoughts about the scope issue:

http://jugad2.blogspot.in/2014/03/flatten-list-of-lists-with-list.html

A few people commented about it, both on my blog, and on the Python Reddit where I also submitted my post, but I'm not sure I'm convinced of their reasoning or understand it, hence posting the question here.

Thanks,
Vasudev Ram
www.dancingbison.com
jugad2.blogspot.com



From rustompmody at gmail.com  Fri Mar 21 16:54:00 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 21 Mar 2014 13:54:00 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
Message-ID: <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>

On Saturday, March 22, 2014 2:12:53 AM UTC+5:30, vasudevram wrote:
> Hi list,

> Can anyone - maybe one of the Python language core team, or someone with knowledge of the internals of Python - can explain why this code works, and whether the different occurrences of the name x in the expression, are in different scopes or not? :

> x = [[1,2], [3,4], [5,6]]
>     [x for x in x for x in x]

> I saw this on a Hacker News thread about Python, and here is a post I wrote that gives more details about it, including relevant links, how I found that it can be extended to a triply-nested list, and my thoughts about the scope issue:

> http://jugad2.blogspot.in/2014/03/flatten-list-of-lists-with-list.html

> A few people commented about it, both on my blog, and on the Python Reddit where I also submitted my post, but I'm not sure I'm convinced of their reasoning or understand it, hence posting the question here.

Lets try without comprehending comprehensions :-) 

>>> x=[[1,2],[3,4]]
>>> for x in x:
...   for x in x:
...      print x
... 
1
2
3
4
>>> 


From vasudevram at gmail.com  Fri Mar 21 16:56:09 2014
From: vasudevram at gmail.com (vasudevram)
Date: Fri, 21 Mar 2014 13:56:09 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
Message-ID: <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>

On Saturday, March 22, 2014 2:24:00 AM UTC+5:30, Rustom Mody wrote:
> Lets try without comprehending comprehensions :-) 
> >>> x=[[1,2],[3,4]]
> 
> >>> for x in x:
> 
> ...   for x in x:
> 
> ...      print x
> 
> ... 
> 
> 1
> 
> 2
> 
> 3
> 
> 4

Nice and all, thanks, but doesn't answer the question.



From rustompmody at gmail.com  Fri Mar 21 17:09:19 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 21 Mar 2014 14:09:19 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
Message-ID: <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>

On Saturday, March 22, 2014 2:26:09 AM UTC+5:30, vasudevram wrote:
> On Saturday, March 22, 2014 2:24:00 AM UTC+5:30, Rustom Mody wrote:
> > Lets try without comprehending comprehensions :-) 
> > >>> x=[[1,2],[3,4]]
> > >>> for x in x:
> > ...   for x in x:
> > ...      print x
> > ... 
> > 1
> > 2
> > 3
> > 4

> Nice and all, thanks, but doesn't answer the question.

Which is?



A 'for' introduces a scope:

>>> x = 42
>>> for x in [1,2,3]:
...   print x
... 
1
2
3

No sign of the 42 --v ie the outer x -- inside because of scope

And so we can do:

>>> x = [1,2,3]
>>> for x in x:
...   print x
... 
1
2
3

which implies that in a "for var in exp: ..."
the exp is evaluated in outer scope whereas the var has a new scope inside
the "..."

Now repeatedly apply that principle to the nested for.
Same principle for nested for in a comprehension.


From ian.g.kelly at gmail.com  Fri Mar 21 17:30:10 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 21 Mar 2014 15:30:10 -0600
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
Message-ID: <CALwzidnuTjs12giQw7CZs++HUK6oR9KEGCHQyBf0iyZnzZkoMQ@mail.gmail.com>

On Fri, Mar 21, 2014 at 3:09 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> A 'for' introduces a scope:

This is false.

>>>> x = 42
>>>> for x in [1,2,3]:
> ...   print x
> ...
> 1
> 2
> 3
>
> No sign of the 42 --v ie the outer x -- inside because of scope

Try printing x again *after* the for loop:

>>> x = 42
>>> for x in [1,2,3]:
...     print(x)
...
1
2
3
>>> print(x)
3

Notice that it's still 3.  If the x in the for loop were really a
separately scoped variable, we would have expected to see 42 here.  In
fact the x used in the for loop and the x used outside of it are the
same x variable.

The real reason that the OP's example works is because each value that
the x variable holds happens to only need to be read once.  Start with
this code, and work through it line-by-line:

x = [[1, 2], [3, 4]]
for x in x:
    for x in x:
        print(x)

Initially, x is assigned the list.  Then we enter the outer for loop.
The expression x is evaluated once to be iterated over.  The first
value that the for loop iterator yields is [1, 2], which is then
assigned to x.  Now we enter the inner for loop.  The expression x is
again evaluated once to be iterated over.  It first yields 1, which is
assigned to x, and then printed.  The inner for loop iterator then
yields 2, which is also assigned to x and printed.  The inner for loop
iterator then raises StopIteration, and the inner for loop terminates.
 The outer for loop iterator then yields [3, 4], and this is assigned
to x.  The inner for loop evaluates this expression and runs as
before.  Afterward, the outer for loop iterator raises StopException,
and that for loop terminates.  The final value of x here will be 4:

>>> x = [[1, 2], [3, 4]]
>>> for x in x:
...     for x in x:
...         print(x)
...
1
2
3
4
>>> print(x)
4

As I hope this makes clear, no nested scopes are needed to make this
happen.  It works because nothing that is stored in x needs to remain
there after the next thing is stored in x.


From cs at zip.com.au  Fri Mar 21 17:32:36 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Sat, 22 Mar 2014 08:32:36 +1100
Subject: Question about Source Control
In-Reply-To: <roy-B841BA.08233121032014@news.panix.com>
References: <roy-B841BA.08233121032014@news.panix.com>
Message-ID: <20140321213236.GA46964@cskk.homeip.net>

On 21Mar2014 08:23, Roy Smith <roy at panix.com> wrote:
> In article <mailman.8348.1395381664.18130.python-list at python.org>,
>  Cameron Simpson <cs at zip.com.au> wrote:
> 
> >   hg blame bin/set-x
> > 
> > and the output goes:
> > 
> >     [hg/css]fleet*> hg blame bin/set-x
> >      2186: #!/bin/sh
> >     11359: #
> >     11359: # Trace execution of a command.
> 
> There's two things hg blame doesn't do which would be useful.
> 
> First, the trivial one.  I don't want lines annotated by change number, 
> I want them annotated by the name of the person who checked it in.

From "hg help blame":

  This command is useful for discovering when a change was made and by whom.

Look at "hg blame -u" or "hg blame -uv".

> The hard thing is I don't really want to know which change most recently 
> touched the line of text.  I want to know who really wrote it.  It would 
> be wonderful if hg were smart enough to be able to back-track through 
> the change history and ignore trivial changes like whitespace, 
> refactoring a function out of one file into another, etc.  That's the 
> real meat and potatoes of "blame".  I want to know who I need to hit 
> over the head with a clue-by-four once I fix a bug.

That would probably be not too hard to script. The tricky bit might be
identifying a particular line as the same over certain diffs.

Basicly, run "hg log" for the file, and examine each of the diffs
WRT to your target line.

Refactoring raises the bar somewhat.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

I am learning that criticism is not nearly as effective as sabotage.
        - Shanti Goldstein


From greg.ewing at canterbury.ac.nz  Fri Mar 21 17:34:48 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Sat, 22 Mar 2014 10:34:48 +1300
Subject: Explanation of this Python language feature? [x for x in x for
 x   in x] (to flatten a nested list)
In-Reply-To: <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
Message-ID: <bp3pjnFscpsU1@mid.individual.net>

Rustom Mody wrote:

> A 'for' introduces a scope:

No, it doesn't!

>>>>x = 42
>>>>for x in [1,2,3]:
> ...   print x
> ... 
> 1
> 2
> 3
> 
> No sign of the 42 --v ie the outer x -- inside because of scope

You're right that there's no sign of the 42, but it's
*not* because of scope, as you'll see if you do one
more print:

 >>> print x
3

> And so we can do:
> 
> 
>>>>x = [1,2,3]
>>>>for x in x:
> ...   print x
> ... 
> 1
> 2
> 3

Again, if you print x after the loop has finished,
you'll find that it's no longer bound to the original
list. This is because Python's for-loop does *not*
introduce a new scope -- there's only one x, and
the for-loop is sharing it with the rest of the code.

The real question is why the for-loop works in *spite*
of this fact.

The answer is that the for-loop machinery keeps an
internal reference to the list being iterated over,
so once the loop has started, it doesn't matter what
x is bound to any more.

-- 
Greg


From ram.rachum at gmail.com  Fri Mar 21 18:05:59 2014
From: ram.rachum at gmail.com (cool-RR)
Date: Fri, 21 Mar 2014 15:05:59 -0700 (PDT)
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
Message-ID: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>

Hi everybody,

I need to install Python 3.4 final urgently, because my IDE stopped supporting Python 3.4 beta2, and I need it urgently to work.

I downloaded it, but the MSI won't install. It didn't work on both of my computers (Windows 7 64bit).

I managed to have the MSI dump data to log, file attached.

I couldn't help but notice this line in the log:

    The installer has encountered an unexpected error installing this package. This may indicate a problem with this package. The error code is 2726. The arguments are: HO_CHI~1|Ho_Chi_Minh

A Google search shows this: http://en.wikipedia.org/wiki/Ho_Chi_Minh

What the hell. Was python.org hacked by communists?

Please, I need to get back to work and I can't. 


Thanks,
Ram.


From ram.rachum at gmail.com  Fri Mar 21 18:08:25 2014
From: ram.rachum at gmail.com (cool-RR)
Date: Fri, 21 Mar 2014 15:08:25 -0700 (PDT)
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
Message-ID: <9a740a79-17fe-40ee-8dfc-4eba914e2072@googlegroups.com>

Sorry, couldn't attach the file, here's the log file:

https://gist.github.com/anonymous/9697505

On Saturday, March 22, 2014 12:05:59 AM UTC+2, cool-RR wrote:
> Hi everybody,
> 
> 
> 
> I need to install Python 3.4 final urgently, because my IDE stopped supporting Python 3.4 beta2, and I need it urgently to work.
> 
> 
> 
> I downloaded it, but the MSI won't install. It didn't work on both of my computers (Windows 7 64bit).
> 
> 
> 
> I managed to have the MSI dump data to log, file attached.
> 
> 
> 
> I couldn't help but notice this line in the log:
> 
> 
> 
>     The installer has encountered an unexpected error installing this package. This may indicate a problem with this package. The error code is 2726. The arguments are: HO_CHI~1|Ho_Chi_Minh
> 
> 
> 
> A Google search shows this: http://en.wikipedia.org/wiki/Ho_Chi_Minh
> 
> 
> 
> What the hell. Was python.org hacked by communists?
> 
> 
> 
> Please, I need to get back to work and I can't. 
> 
> 
> 
> 
> 
> Thanks,
> 
> Ram.


From rosuav at gmail.com  Fri Mar 21 18:17:07 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 09:17:07 +1100
Subject: Question about Source Control
In-Reply-To: <20140321213236.GA46964@cskk.homeip.net>
References: <roy-B841BA.08233121032014@news.panix.com>
 <20140321213236.GA46964@cskk.homeip.net>
Message-ID: <CAPTjJmp39h2zBRjvoT1rQBH07FMY8Kq2Ub+bcYyGQA7hsOdBRg@mail.gmail.com>

On Sat, Mar 22, 2014 at 8:32 AM, Cameron Simpson <cs at zip.com.au> wrote:
> Basicly, run "hg log" for the file, and examine each of the diffs
> WRT to your target line.
>
> Refactoring raises the bar somewhat.

Here's one where git and hg are a lot more different.

When I'm trying to find the origin of some line of code in a git repo,
I often make a dummy edit to it, then pull up gitk, right-click the
red "deleted" line, and hit "Show origin of this line". This will
select the commit that introduced that one line, without annotating
the whole rest of the file (often a slow job, especially on a big
file), and then I can go from the green inserted line to the
corresponding red deleted line and repeat the exercise (eg if some
trivial change was made, like renaming something). I'm trying that
workflow with "hg view", the nearest equivalent to gitk, but it's way
slower and doesn't seem to have a right-click menu at all, so I'm not
sure this is possible. Is there a convenient way to trace the origin
of one line back through a few commits?

ChrisA


From rosuav at gmail.com  Fri Mar 21 18:25:03 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 09:25:03 +1100
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
Message-ID: <CAPTjJmriw032SAXbsCTc4_fPyEvUOgUB-FNMB-HMWEJhRJocVg@mail.gmail.com>

On Sat, Mar 22, 2014 at 9:05 AM, cool-RR <ram.rachum at gmail.com> wrote:
> I downloaded it, but the MSI won't install. It didn't work on both of my computers (Windows 7 64bit).
>
> What the hell. Was python.org hacked by communists?

First question: Where did you download from? What file did you get?

(First and a halfth question: When you say "won't install", exactly
what do you mean? Error message? Hard drive exploded in a fiery
inferno? Your boss tapped you on the shoulder and said "Kill that
process"?)

Secondly, do you have a tool for checking the MD5 hash of a file?
Compare the file you have against the official checksum:

https://www.python.org/downloads/release/python-340/

I'm slightly surprised the python.org installers have MD5s and not
something more cryptographically secure; there are GPG signatures, but
it takes a bit more fiddling to check those.

Finally, take the simple approach: Re-download the file, straight from
python.org, and see if it happens again.

ChrisA


From ram.rachum at gmail.com  Fri Mar 21 18:34:06 2014
From: ram.rachum at gmail.com (cool-RR)
Date: Fri, 21 Mar 2014 15:34:06 -0700 (PDT)
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <mailman.8372.1395441071.18130.python-list@python.org>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
Message-ID: <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>

I did download from python.org. I checked the md5, it was incorrect, then I downloaded again by using a proxy in Austria. (Which hopefully the communists haven't be able to infiltrate? ;)

Now it worked! Woohoo!

I'm still curious about the bad installation file... And what Ho Chi Minh is doing in the Python MSI. (I'm guessing it's timezone-related, but it's still far-fetched, because why would an obscure time zone file appear in the MSI log?)

On Saturday, March 22, 2014 12:25:03 AM UTC+2, Chris Angelico wrote:
> On Sat, Mar 22, 2014 at 9:05 AM, cool-RR <ram.rachum at gmail.com> wrote:
> 
> > I downloaded it, but the MSI won't install. It didn't work on both of my computers (Windows 7 64bit).
> 
> >
> 
> > What the hell. Was python.org hacked by communists?
> 
> 
> 
> First question: Where did you download from? What file did you get?
> 
> 
> 
> (First and a halfth question: When you say "won't install", exactly
> 
> what do you mean? Error message? Hard drive exploded in a fiery
> 
> inferno? Your boss tapped you on the shoulder and said "Kill that
> 
> process"?)
> 
> 
> 
> Secondly, do you have a tool for checking the MD5 hash of a file?
> 
> Compare the file you have against the official checksum:
> 
> 
> 
> https://www.python.org/downloads/release/python-340/
> 
> 
> 
> I'm slightly surprised the python.org installers have MD5s and not
> 
> something more cryptographically secure; there are GPG signatures, but
> 
> it takes a bit more fiddling to check those.
> 
> 
> 
> Finally, take the simple approach: Re-download the file, straight from
> 
> python.org, and see if it happens again.
> 
> 
> 
> ChrisA



From ram.rachum at gmail.com  Fri Mar 21 18:34:49 2014
From: ram.rachum at gmail.com (cool-RR)
Date: Fri, 21 Mar 2014 15:34:49 -0700 (PDT)
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
Message-ID: <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>

Here's the offending MSI, if anyone wants to investigate: https://dl.dropboxusercontent.com/u/1927707/python-3.4.0.amd64.msi


On Saturday, March 22, 2014 12:34:06 AM UTC+2, cool-RR wrote:
> I did download from python.org. I checked the md5, it was incorrect, then I downloaded again by using a proxy in Austria. (Which hopefully the communists haven't be able to infiltrate? ;)
> 
> 
> 
> Now it worked! Woohoo!
> 
> 
> 
> I'm still curious about the bad installation file... And what Ho Chi Minh is doing in the Python MSI. (I'm guessing it's timezone-related, but it's still far-fetched, because why would an obscure time zone file appear in the MSI log?)
> 
> 
> 
> On Saturday, March 22, 2014 12:25:03 AM UTC+2, Chris Angelico wrote:
> 
> > On Sat, Mar 22, 2014 at 9:05 AM, cool-RR <ram.rachum at gmail.com> wrote:
> 
> > 
> 
> > > I downloaded it, but the MSI won't install. It didn't work on both of my computers (Windows 7 64bit).
> 
> > 
> 
> > >
> 
> > 
> 
> > > What the hell. Was python.org hacked by communists?
> 
> > 
> 
> > 
> 
> > 
> 
> > First question: Where did you download from? What file did you get?
> 
> > 
> 
> > 
> 
> > 
> 
> > (First and a halfth question: When you say "won't install", exactly
> 
> > 
> 
> > what do you mean? Error message? Hard drive exploded in a fiery
> 
> > 
> 
> > inferno? Your boss tapped you on the shoulder and said "Kill that
> 
> > 
> 
> > process"?)
> 
> > 
> 
> > 
> 
> > 
> 
> > Secondly, do you have a tool for checking the MD5 hash of a file?
> 
> > 
> 
> > Compare the file you have against the official checksum:
> 
> > 
> 
> > 
> 
> > 
> 
> > https://www.python.org/downloads/release/python-340/
> 
> > 
> 
> > 
> 
> > 
> 
> > I'm slightly surprised the python.org installers have MD5s and not
> 
> > 
> 
> > something more cryptographically secure; there are GPG signatures, but
> 
> > 
> 
> > it takes a bit more fiddling to check those.
> 
> > 
> 
> > 
> 
> > 
> 
> > Finally, take the simple approach: Re-download the file, straight from
> 
> > 
> 
> > python.org, and see if it happens again.
> 
> > 
> 
> > 
> 
> > 
> 
> > ChrisA


From rosuav at gmail.com  Fri Mar 21 18:42:56 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 09:42:56 +1100
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
Message-ID: <CAPTjJmp5TWg4bUSXh8tzLDZv5wdskt_4x+w9Fb+i_PhW2HJk9w@mail.gmail.com>

On Sat, Mar 22, 2014 at 9:34 AM, cool-RR <ram.rachum at gmail.com> wrote:
> I did download from python.org. I checked the md5, it was incorrect, then I downloaded again by using a proxy in Austria. (Which hopefully the communists haven't be able to infiltrate? ;)
>

I think you should follow the internet version of Hanlon's Razor here:
Damaged transmission before deliberate tampering. :) It's far more
likely something simply got misdownloaded, and your guess about
timezones is the most likely one - the Asia/Ho_Chi_Minh timezone [1],
and I believe Python Windows installers include a full zoneinfo
database.

ChrisA

[1] See https://en.wikipedia.org/wiki/Ho_Chi_Minh_City


From breamoreboy at yahoo.co.uk  Fri Mar 21 18:44:03 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Fri, 21 Mar 2014 22:44:03 +0000
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
Message-ID: <lgifba$c5p$1@ger.gmane.org>

On 21/03/2014 22:34, cool-RR wrote:

I'm pleased to see that you have answers.  In return would you either 
use the mailing list 
https://mail.python.org/mailman/listinfo/python-list or read and action 
this https://wiki.python.org/moin/GoogleGroupsPython to prevent us 
seeing double line spacing and single line paragraphs, thanks.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Fri Mar 21 18:50:07 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 09:50:07 +1100
Subject: Implement multiprocessing without inheriting parent file handle
In-Reply-To: <lghvlr$bqs$1@speranza.aioe.org>
References: <mailman.8363.1395415712.18130.python-list@python.org>
 <878us35tz8.fsf@elektro.pacujo.net>
 <lghvlr$bqs$1@speranza.aioe.org>
Message-ID: <CAPTjJmocSBmjKZOJ3aTipXkADXUrGmGBv7u07CJnmYY842+Pfg@mail.gmail.com>

On Sat, Mar 22, 2014 at 5:16 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/21/14 12:42 PM, Marko Rauhamaa wrote:
>>
>>    http://docs.python.org/3/library/subprocess.html#popen-constructor>
>
>
>> It's got the optional close_fds parameter, which is True by default.
>
>
>> IOW, you don't need to do anything if you use subprocess.Popen() to
>> start your child process. Incidentally, that's the preferred way.
>
>
> hi Marko, of course this depends on the environment; if unix-like, then yes,
> elif windows well, not so much...
>
> There are caveats about stdin, stdout, and stderr;  as well, there are
> caveats about passing fds between the two. Well, Popen() is implemented on
> unix and windows differently, so there is some study needed here if code is
> going to be run in both environments.

There were some recent changes, though, including making CLOEXEC the
default, which means that fork/exec on Unix will retain only the fds
you actually want.

ChrisA


From ram.rachum at gmail.com  Fri Mar 21 18:50:02 2014
From: ram.rachum at gmail.com (cool-RR)
Date: Fri, 21 Mar 2014 15:50:02 -0700 (PDT)
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <mailman.8373.1395441784.18130.python-list@python.org>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <mailman.8373.1395441784.18130.python-list@python.org>
Message-ID: <9458beea-9dcd-4dfe-8b94-a4516a7873e1@googlegroups.com>

On Saturday, March 22, 2014 12:42:56 AM UTC+2, Chris Angelico wrote:
> I think you should follow the internet version of Hanlon's Razor here:
> Damaged transmission before deliberate tampering. :) It's far more
> likely something simply got misdownloaded, and your guess about
> timezones is the most likely one - the Asia/Ho_Chi_Minh timezone [1],
> and I believe Python Windows installers include a full zoneinfo
> database.


The thing is, I then tried other versions of Python 3.4, like b2, and the 32 bit version, and they didn't work either... So damaged transmission of 3 separate files? I'm not seeing any other damaged files when surfing using this connection.


From ram.rachum at gmail.com  Fri Mar 21 18:55:42 2014
From: ram.rachum at gmail.com (cool-RR)
Date: Fri, 21 Mar 2014 15:55:42 -0700 (PDT)
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <mailman.8372.1395441071.18130.python-list@python.org>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
Message-ID: <793ecef5-2025-4714-a6a4-cff13c93f45d@googlegroups.com>

On Saturday, March 22, 2014 12:25:03 AM UTC+2, Chris Angelico wrote:
> (First and a halfth question: When you say "won't install", exactly
> what do you mean?

For completeness, I'll answer this question I forgot to answer, in case someone still wants to investigate: It just showed the first dialog (Something like "Preparing to install..."), after a few seconds it disappeared and then nothing.


From fiensproto at gmail.com  Fri Mar 21 20:22:02 2014
From: fiensproto at gmail.com (fiensproto at gmail.com)
Date: Fri, 21 Mar 2014 17:22:02 -0700 (PDT)
Subject: CallBack function in C Libraries.
In-Reply-To: <lghqk7$suf$1@speranza.aioe.org>
References: <a9908cb7-3566-42a8-a468-8179ac1df7ab@googlegroups.com>
 <lgfucb$4q7$1@speranza.aioe.org>
 <e469fc0a-596c-40b6-8b27-751a4fe84d85@googlegroups.com>
 <op.xc1uldoj5079vu@gnudebeest>
 <488fbd2c-1b99-482d-a282-f3f20defbc68@googlegroups.com>
 <lghqk7$suf$1@speranza.aioe.org>
Message-ID: <c451c8e3-90fb-40b9-85a5-cdcb6e9efb8a@googlegroups.com>

Le vendredi 21 mars 2014 16:50:18 UTC, Mark H. Harris a ?crit?:
> > def TheProc():         <================== you moved c_int from here ...
> 
> >      fpgui.fpgFormWindowTitle(0, 'Boum')
> 
> >      return 0

> > CMPFUNC = CFUNCTYPE(c_int)   <============ and placed it here ...

> 
> 
> ... it wasn't "expecting" exactly one parameter. So, your python 
> 
> traceback no longer warns about the parameter 'mismatch' in the defined 
> 
> function  TheProc().
> 
> 
> 
>     I'm not picking on you, but this error was obvious; as was it's 
> 
> solution, so I'm just wondering ?
> 

Hello and thanks for answer.

Hum, i do not understand why, but the code is working ... ;-)

Some remarks :

> def TheProc():   
>      fpgui.fpgFormWindowTitle(0, 'Boum')
>      return 0        <================== that does the trick...


And 

> > CMPFUNC = CFUNCTYPE(c_int)   <======== 1 argument minimum..

It seems that CFUNCTYPE() want minimum 1 argument, even if TheProc() is a simple procedure, without argument...

Hum, it is my really first program in Python and im impressed how easy it was to do my Pascal (fpc) library work!
Im busy to try to do it work for java programs but it is not so easy.

By the way, is it possible to hide the terminal-window ?

That library is a complete graphic widget set (from Form to Stringgrid and more).
So, i will prefer that the console was hided...

And last question, how to retrieve the directory of the main Python application ?

Many thanks.


From dan at tombstonezero.net  Fri Mar 21 20:57:03 2014
From: dan at tombstonezero.net (Dan Sommers)
Date: Sat, 22 Mar 2014 00:57:03 +0000 (UTC)
Subject: Github down?
References: <CANc-5Uxf71ZEOtqHzYbgB3Gg5jwQM-=oYefdKL2bq=En+P1jTQ@mail.gmail.com>
 <CACwCsY7-mVjdvGdhN5VDohp2Sjujo3t=xUkN6ZwhXuFp1A9YdQ@mail.gmail.com>
 <CANc-5Uw0r=CNvj1Q7dfzqLGDp_f+3dZwiQtaKsQXjhbK2HnnZQ@mail.gmail.com>
 <mailman.8356.1395409923.18130.python-list@python.org>
Message-ID: <lgin4u$qsv$1@dont-email.me>

On Fri, 21 Mar 2014 14:51:54 +0100, Chris ?Kwpolska? Warrick wrote:

> (though GitHub could qualify as social media for some?)

+1 QOTW


From tjreedy at udel.edu  Fri Mar 21 21:39:21 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Fri, 21 Mar 2014 21:39:21 -0400
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <793ecef5-2025-4714-a6a4-cff13c93f45d@googlegroups.com>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <793ecef5-2025-4714-a6a4-cff13c93f45d@googlegroups.com>
Message-ID: <lgipk1$7ji$1@ger.gmane.org>

On 3/21/2014 6:55 PM, cool-RR wrote:
> On Saturday, March 22, 2014 12:25:03 AM UTC+2, Chris Angelico wrote:
>> (First and a halfth question: When you say "won't install", exactly
>> what do you mean?
>
> For completeness, I'll answer this question I forgot to answer, in case someone still wants to investigate: It just showed the first dialog (Something like "Preparing to install..."), after a few seconds it disappeared and then nothing.

Does your .b2 install work? Can you delete it thru the programs list?

-- 
Terry Jan Reedy



From rustompmody at gmail.com  Fri Mar 21 22:06:06 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 21 Mar 2014 19:06:06 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8369.1395437459.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
Message-ID: <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>

On Saturday, March 22, 2014 3:00:10 AM UTC+5:30, Ian wrote:
> On Fri, Mar 21, 2014 at 3:09 PM, Rustom Mody  wrote:
> > A 'for' introduces a scope:

> This is false.


And 

On Saturday, March 22, 2014 3:04:48 AM UTC+5:30, Gregory Ewing wrote:

> > A 'for' introduces a scope:

> No, it doesn't!


Ha -- funny that *I* missed that one. Thanks both Ian and Gregory

In fact one of my grumbles against python is that list comprehension's
are a poor imitation of haskell's comprehensions.

And then I promptly forgot about it!

Actually there are two leakages in python 2, one of which is corrected
in python 3.

One: a comprehension variable leaks outside after the comprehension
This is corrected in python3.  
Two: A comprehension variable is not bound but reassigned across the
comprehension. This problem remains in python3 and causes weird behavior when
lambdas are put in a comprehension

>>> fl = [lambda y : x+y for x in [1,2,3]]
>>> [fl[i](2) for i in [0,1,2]]
[5, 5, 5]

The same in haskell:

Prelude> let fl = [\ y -> x + y | x <- [1,2,3]]
Prelude> [(fl!!i) 0 | i<- [0,1,2]]
[1,2,3]


From rosuav at gmail.com  Fri Mar 21 22:41:27 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 13:41:27 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
Message-ID: <CAPTjJmoQUk+S1nai18Bfy2faMivEWHeUUpja6NhpPvBxM5LLDA@mail.gmail.com>

On Sat, Mar 22, 2014 at 1:06 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> Two: A comprehension variable is not bound but reassigned across the
> comprehension. This problem remains in python3 and causes weird behavior when
> lambdas are put in a comprehension
>
>>>> fl = [lambda y : x+y for x in [1,2,3]]
>>>> [fl[i](2) for i in [0,1,2]]
> [5, 5, 5]

To clarify, what you're saying here is that x in the first
comprehension's closures should be bound to separate values for x,
yes?

I'm not sure how that ought to be done. Having closures that can
reference and modify each other's variables is important.

def func_pair():
    x = 0
    def inc():
        nonlocal x; x+=1
        return x
    def dec():
        nonlocal x; x-=1
        return x
    return inc, dec

fooup, foodn = func_pair()
barup, bardn = func_pair()
>>> fooup(), fooup(), fooup(), foodn()
(1, 2, 3, 2)
>>> barup(), barup(), bardn(), bardn()
(1, 2, 1, 0)

Those functions are fundamentally linked. Very useful with callbacks.
A nice alternative to doing everything with bound methods.

So if that's not going to be broken, how is this fundamentally different?

def func_loop():
    for x in 1,2,3:
        yield (lambda: x)

one, two, three = func_loop()
one(), one(), two(), two(), three(), three()

This one does NOT work the way the names imply, and I can see that
you'd like to fix it. But I can't pinpoint a significant difference
between them. How do you distinguish?

ChrisA


From cs at zip.com.au  Fri Mar 21 22:49:33 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Sat, 22 Mar 2014 13:49:33 +1100
Subject: Question about Source Control
In-Reply-To: <CAPTjJmp39h2zBRjvoT1rQBH07FMY8Kq2Ub+bcYyGQA7hsOdBRg@mail.gmail.com>
References: <CAPTjJmp39h2zBRjvoT1rQBH07FMY8Kq2Ub+bcYyGQA7hsOdBRg@mail.gmail.com>
Message-ID: <20140322024933.GA51643@cskk.homeip.net>

On 22Mar2014 09:17, Chris Angelico <rosuav at gmail.com> wrote:
> On Sat, Mar 22, 2014 at 8:32 AM, Cameron Simpson <cs at zip.com.au> wrote:
> > Basicly, run "hg log" for the file, and examine each of the diffs
> > WRT to your target line.
> >
> > Refactoring raises the bar somewhat.
> 
> Here's one where git and hg are a lot more different.

You might find it is just a matter of knowing what tool to use.

> When I'm trying to find the origin of some line of code in a git repo,
> I often make a dummy edit to it, then pull up gitk, right-click the
> red "deleted" line, and hit "Show origin of this line". This will
> select the commit that introduced that one line, without annotating
> the whole rest of the file (often a slow job, especially on a big
> file), and then I can go from the green inserted line to the
> corresponding red deleted line and repeat the exercise (eg if some
> trivial change was made, like renaming something). I'm trying that
> workflow with "hg view", the nearest equivalent to gitk, but it's way
> slower and doesn't seem to have a right-click menu at all, so I'm not
> sure this is possible. Is there a convenient way to trace the origin
> of one line back through a few commits?

I don't know.

You might do better to ask this kind of question on the mercurial list:

  http://selenic.com/mailman/listinfo/mercurial

Someone there is bound to have wanted to do this kind of thing, and
may know if there's a tool or extension that makes it easy. There's
a whole expression syntax for getting mercurial to select from the
revision tree, for example; I do not know if it is applicable in
this case.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

Do what you think is interesting, do something that you think is fun
and worthwhile, because otherwise you won't do it well anyway.
- Brian Kernighan


From harrismh777 at gmail.com  Fri Mar 21 22:51:09 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 21 Mar 2014 21:51:09 -0500
Subject: Installing ssdeep on Portable Python /advice
References: <mailman.8331.1395360978.18130.python-list@python.org>
Message-ID: <lgitqs$ok4$2@speranza.aioe.org>

On 3/20/14 7:16 PM, laguna-mc at mail.com wrote:

>      $ tar -zxvf ssdeep-2.10.tar.gz
>      $ cd ssdeep-2.10&&  ./configure&&  make&&  sudo make install

> I need install it on PortablePython for Windows, so it's not
> clear how to make this: where should be placed ssdeep Windows
> binary files, that Python application can found it?

It is strongly recommended that ssdeep be run on windows from 
precompiled binaries.  Building from sources is not recommended because 
of dependencies and environment...

Google is our frined;

http://ssdeep.sourceforge.net/usage.html


marcus


From rosuav at gmail.com  Fri Mar 21 23:05:21 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 14:05:21 +1100
Subject: Question about Source Control
In-Reply-To: <20140322024933.GA51643@cskk.homeip.net>
References: <CAPTjJmp39h2zBRjvoT1rQBH07FMY8Kq2Ub+bcYyGQA7hsOdBRg@mail.gmail.com>
 <20140322024933.GA51643@cskk.homeip.net>
Message-ID: <CAPTjJmq7328mniv0D7-=pH=_NtytQLq93w8AXFErUHdXHKVthg@mail.gmail.com>

On Sat, Mar 22, 2014 at 1:49 PM, Cameron Simpson <cs at zip.com.au> wrote:
> You might do better to ask this kind of question on the mercurial list:
>
>   http://selenic.com/mailman/listinfo/mercurial
>
> Someone there is bound to have wanted to do this kind of thing, and
> may know if there's a tool or extension that makes it easy.

I don't personally need it, because all my code is stored in git (as
are most of the other big projects that I'm involved in); was mainly
wondering if someone happened to know, such that Frank could make use
of it. But it's a suggested workflow, and if it appeals to someone,
they can raise the issue on Mercurial's list.

ChrisA


From harrismh777 at gmail.com  Fri Mar 21 23:32:43 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 21 Mar 2014 22:32:43 -0500
Subject: Installing ssdeep on Portable Python /advice
References: <mailman.8331.1395360978.18130.python-list@python.org>
 <lgitqs$ok4$2@speranza.aioe.org>
Message-ID: <lgj08q$tmp$1@speranza.aioe.org>

On 3/21/14 9:51 PM, Mark H Harris wrote:
> On 3/20/14 7:16 PM, laguna-mc at mail.com wrote:

>> $ tar -zxvf ssdeep-2.10.tar.gz
>> $ cd ssdeep-2.10&& ./configure&& make&& sudo make install

>> I need install it on PortablePython for Windows, so it's not
>> clear how to make this: where should be placed ssdeep Windows
>> binary files, that Python application can found it?

> It is strongly recommended that ssdeep be run on windows from
> precompiled binaries. Building from sources is not recommended because
> of dependencies and environment...

> Google is our frined;

> http://ssdeep.sourceforge.net/usage.html


Actually, I restated that wrong. The doc says that building from sources 
on windows is NOT supported.

marcus


From harrismh777 at gmail.com  Fri Mar 21 23:58:37 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 21 Mar 2014 22:58:37 -0500
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
Message-ID: <lgj1pd$10g$1@speranza.aioe.org>

On 3/21/14 5:44 PM, Mark Lawrence wrote:
> I'm pleased to see that you have answers. In return would you either use
> the mailing list https://mail.python.org/mailman/listinfo/python-list or
> read and action this https://wiki.python.org/moin/GoogleGroupsPython to
> prevent us seeing double line spacing and single line paragraphs, thanks.

I perceive that this is your singular pet peeve, or, you were elected by 
the python community some time ago to police the line-end problem ?

I notice (since moving my stuff to Thunderbird two weeks back) the 
double spacing you keep squawking about, but I don't find it the big 
nuisance you're talking about; ok, so we have to scroll a bit further.

I am honestly convinced that this might even be a python problem.  More 
likely than not, gg is written in python, and this is the goofy line-end 
character problem we have to deal with when we read lines in python.

Why do we suck in the new-line character as though it were part of the 
line?  This is asinine behavior.  The new-line is a "file" delimiter 
character and NOT intended to be part of the line.

Thinking this through a bit I've noticed that a blank line comes back 
with a '\n'  which differentiates it from file end which comes back 
"without" the new-line.  So, it appears that python is using the 
new-line character (or lack there-of) to have meaning which the new=line 
in a unix file was never suppose to carry.

If python would just return EOF like every other language at file end, 
and a test line without '\n' tacked to the end of it, this little snag 
with gg would probably go away.  What say you?

Of course, that does not alleviate all of the rest of gg's short 
comings!   <sigh>

marcus



From rosuav at gmail.com  Sat Mar 22 00:15:21 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 15:15:21 +1100
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <lgj1pd$10g$1@speranza.aioe.org>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
Message-ID: <CAPTjJmoYwC2Q3VH_0R69weh4QtB1ZD0Z4phNZriTfmgJC909ZA@mail.gmail.com>

On Sat, Mar 22, 2014 at 2:58 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/21/14 5:44 PM, Mark Lawrence wrote:
>>
>> I'm pleased to see that you have answers. In return would you either use
>> the mailing list https://mail.python.org/mailman/listinfo/python-list or
>> read and action this https://wiki.python.org/moin/GoogleGroupsPython to
>> prevent us seeing double line spacing and single line paragraphs, thanks.
>
>
> I perceive that this is your singular pet peeve, or, you were elected by the
> python community some time ago to police the line-end problem ?

Communities maintain standards by policing them. If nobody cares
enough to post, the problem will remain. He happens to be one of the
most frequent commenters on this particular issue, but believe you me,
he is not the only one to wish it were solved; I used to speak up too,
but became tired of saying it (and of the blowback), and now I ignore
all double-spaced junk. If I can't figure out what's going on without
the context, I'll just move on to the next post.

> I notice (since moving my stuff to Thunderbird two weeks back) the double
> spacing you keep squawking about, but I don't find it the big nuisance
> you're talking about; ok, so we have to scroll a bit further.

It compounds. One reply makes for double spacing... two makes
quadruple, three means we have seven wasted lines between every pair
of real lines. That gets pretty annoying. And considering that most
people who reply without cleaning up the lines also keep the entire
quoted text (and usually top-post as well), this gets big fast.

> I am honestly convinced that this might even be a python problem.  More
> likely than not, gg is written in python, and this is the goofy line-end
> character problem we have to deal with when we read lines in python.

No idea why you should think this; it's more likely to be based on
HTML parsing (newline -> paragraph -> double newline), especially
since the original text is usually unwrapped.

> Why do we suck in the new-line character as though it were part of the line?
> This is asinine behavior.  The new-line is a "file" delimiter character and
> NOT intended to be part of the line.
>
> Thinking this through a bit I've noticed that a blank line comes back with a
> '\n'  which differentiates it from file end which comes back "without" the
> new-line.  So, it appears that python is using the new-line character (or
> lack there-of) to have meaning which the new=line in a unix file was never
> suppose to carry.
>
> If python would just return EOF like every other language at file end, and a
> test line without '\n' tacked to the end of it, this little snag with gg
> would probably go away.  What say you?

Personally, I think that iterating over the lines in a file (in the
most obvious way) should strip delimiters. There should be a
less-obvious way to iterate over the "lines complete with their line
ends", which can then be used to distinguish between the different
line endings (including the absence of one at the end of the file),
but most of the time you want to just treat a file as a series of
lines, and don't care about the distinctions. However, that ship has
sailed; it's way WAY too late to make any such change.

And changing it would not fix the Google Groups problem unless it also
broke a whole pile of other code out there.

ChrisA


From harrismh777 at gmail.com  Sat Mar 22 00:30:06 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 21 Mar 2014 23:30:06 -0500
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <mailman.8380.1395461724.18130.python-list@python.org>
Message-ID: <lgj3kd$4th$1@speranza.aioe.org>

On 3/21/14 11:15 PM, Chris Angelico wrote:
> It compounds. One reply makes for double spacing... two makes
> quadruple, three means we have seven wasted lines between every pair
> of real lines. That gets pretty annoying. And considering that most
> people who reply without cleaning up the lines also keep the entire
> quoted text (and usually top-post as well), this gets big fast.

    Yes, I can see that readily/  I get it, it just seems that fixing it 
at the source (gg) is the answer; because there will always be someone 
new to the list who is using gg because its part of their suite and 
because its convenient (I mean, that's why I tried to use it). I think 
we need to be beating up on the gg people so they get their stuff working.

> Personally, I think that iterating over the lines in a file (in the
> most obvious way) should strip delimiters.

    agreed.

> most of the time you want to just treat a file as a series of
> lines, and don't care about the distinctions. However, that ship has
> sailed; it's way WAY too late to make any such change.

    agreed again, on both counts.

> And changing it would not fix the Google Groups problem unless it also
> broke a whole pile of other code out there.

    No doubt.  Well, I don't mind dealing with it/  and frankly, I don't 
really think its a python problem anyway at the root. All files should 
have standard delimiters.  What I used to call flat-text files should 
have standard line-end delimiters, and standard file-end EOF markers. 
All OS's should comply with the standard... for instance, there should 
not be a windows x'0a' x'0d' line ending, and a unix  x'0d' line ending.

    Well, and now that I'm thinking about this again, since we have 
unicode, maybe we should have an entire set of standard "file" 
delimiters for flat-files.

    But the bottom line (pun intended) is that I just want to suck the 
lines in, and I only want the system to have to handle the delimiters; 
I'm not asking for any changes mind you (at this point) just thinking 
out-loud.

Cheers dude.


From harrismh777 at gmail.com  Sat Mar 22 00:36:27 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 21 Mar 2014 23:36:27 -0500
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <mailman.8380.1395461724.18130.python-list@python.org>
 <lgj3kd$4th$1@speranza.aioe.org>
Message-ID: <lgj40a$5cu$1@speranza.aioe.org>

On 3/21/14 11:30 PM, Mark H Harris wrote:
> All OS's should comply with the standard... for instance, there should
> not be a windows x'0a' x'0d' line ending, and a unix x'0d' line ending.


whoops...  I meant  unix  x'0a' line ending...    ;-)


'\n'

:-))


From rustompmody at gmail.com  Sat Mar 22 00:39:55 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 21 Mar 2014 21:39:55 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8377.1395456097.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
Message-ID: <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>

On Saturday, March 22, 2014 8:11:27 AM UTC+5:30, Chris Angelico wrote:
> On Sat, Mar 22, 2014 at 1:06 PM, Rustom Mody wrote:
> > Two: A comprehension variable is not bound but reassigned across the
> > comprehension. This problem remains in python3 and causes weird behavior when
> > lambdas are put in a comprehension
> >>>> fl = [lambda y : x+y for x in [1,2,3]]
> >>>> [fl[i](2) for i in [0,1,2]]
> > [5, 5, 5]

> To clarify, what you're saying here is that x in the first
> comprehension's closures should be bound to separate values for x,
> yes?

Yes

> I'm not sure how that ought to be done.

Thats an implementation question -- see below.

> Having closures that can
> reference and modify each other's variables is important.

Yes

> def func_pair():
>     x = 0
>     def inc():
>         nonlocal x; x+=1
>         return x
>     def dec():
>         nonlocal x; x-=1
>         return x
>     return inc, dec

> fooup, foodn = func_pair()
> barup, bardn = func_pair()
> >>> fooup(), fooup(), fooup(), foodn()
> (1, 2, 3, 2)
> >>> barup(), barup(), bardn(), bardn()
> (1, 2, 1, 0)

> Those functions are fundamentally linked. Very useful with callbacks.
> A nice alternative to doing everything with bound methods.

Yes

> So if that's not going to be broken, how is this fundamentally different?

> def func_loop():
>     for x in 1,2,3:
>         yield (lambda: x)

Thats using a for-loop
A 'for' in a comprehension carries a different intention, the matching names
being merely coincidental.

This 'pun' causes cognitive dissonance in all these questions, including
my gaffe above

> one, two, three = func_loop()
> one(), one(), two(), two(), three(), three()

> This one does NOT work the way the names imply, and I can see that
> you'd like to fix it. But I can't pinpoint a significant difference
> between them. How do you distinguish?

Using closures for carrying state is a different question

As for comprehensions, the appropriate *intention* would be like this:

Given

fl = [lambda y : x+y for x in [1,2,3]] 

It means:

def rec(l):
   if not l: return []
   else:
     x,ll = l[0],l[1:]    
     return [lambda y: x + y] + rec(ll)

followed by
fl = rec([1,2,3])

Naturally a reasonable *implementation* would carry this *intention* more
efficiently with standard techniques like
1. Using list extend/append methods
2. Using lambda y, x=x: x+y

Inside an implementation this is fine
Forcing such tricks as kosher on a programmer is not (IMHO)

[But then I find Lisp and much of basic haskell natural and most of C++ not,
so my views are likely prejudiced :-)



From rosuav at gmail.com  Sat Mar 22 00:46:22 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 15:46:22 +1100
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <lgj3kd$4th$1@speranza.aioe.org>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <mailman.8380.1395461724.18130.python-list@python.org>
 <lgj3kd$4th$1@speranza.aioe.org>
Message-ID: <CAPTjJmqHOivfmvnqG85s_m4nc-ZgJX2Sbs1g7PY5U+3T1B0WqA@mail.gmail.com>

On Sat, Mar 22, 2014 at 3:30 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> All files should have standard delimiters.  What I used to call flat-text
> files should have standard line-end delimiters, and standard file-end EOF
> markers. All OS's should comply with the standard... for instance, there
> should not be a windows x'0a' x'0d' line ending, and a unix  x'0d' line
> ending.

(Side point: You have your 0d and your 0a backwards; the Unix line
ending is U+000A, and the Windows default is U+000D U+000A.)

How are you going to make people change? What are you going to make
them change to? Who controls this standard, and how do you convince
all OSes to comply with it?

ChrisA


From steve+comp.lang.python at pearwood.info  Sat Mar 22 00:47:36 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 22 Mar 2014 04:47:36 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
Message-ID: <532d15e8$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Fri, 21 Mar 2014 19:06:06 -0700, Rustom Mody wrote:

> Two: A comprehension variable is not bound but reassigned across the
> comprehension. This problem remains in python3 and causes weird behavior
> when lambdas are put in a comprehension

I don't know why you say the behaviour in Python is a problem. It's 
somewhat unexpected if you don't think about what's going on, but it's 
actually quite logical. On the contrary, I find the Haskell version weird.


>>>> fl = [lambda y : x+y for x in [1,2,3]] 
>>>> [fl[i](2) for i in [0,1,2]]
> [5, 5, 5]

This makes perfect sense: by the time you call the functions, the name x 
has been rebound to the value 3. If x were a global, or if comprehensions 
leaked their variable, that would be obvious: you could print x and see 
exactly what value it has. But visible or not, that's exactly what 
happens. Since x is 3, you're adding 3+2 and should get 5 no matter which 
function you call.

Unroll the first comprehension, and it's obvious what is going on:

def unrolled():
    fl = []
    x = 0
    def lambda_(y):
        return x + y
    fl.append(lambda_)
    x = 1
    def lambda_(y):
        return x + y
    fl.append(lambda_)
    x = 2
    def lambda_(y):
        return x + y
    fl.append(lambda_)
    return [f(2) for f in fl]

Don't be fooled by the coincidence that the three "lambda_" functions 
have the same name and body. They could have different names and 
different bodies, Either way, it is completely natural that they all 
closures over the same x -- that's how you wrote them.


But the Haskell version, on the other hand, is just weird:

> The same in haskell:
> 
> Prelude> let fl = [\ y -> x + y | x <- [1,2,3]] 
> Prelude> [(fl!!i) 0 | i<- [0,1,2]]
> [1,2,3]

For this to be the case, the functions in fl have to somehow "look back 
in time" to see the value of x, not as it is *now* when the function is 
called, but how it *was* when it was created. That's very weird indeed. 
If x were a global, it would be astonishing. The fact that x comes from a 
closure instead makes it no less surprising. Unroll the loop, and the 
magic is obvious.

Now I'm not sure precisely how Haskell implements this trick, but it 
suggests to me that it creates a different closure each time around the 
loop of the comprehension. That could end up being very expensive.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Sat Mar 22 00:51:13 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 15:51:13 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
Message-ID: <CAPTjJmqwEoHBXXaipRU8rkWrQ2O_-Mc03rno93bsCvjK6zDP+A@mail.gmail.com>

On Sat, Mar 22, 2014 at 3:39 PM, Rustom Mody <rustompmody at gmail.com> wrote:
>> So if that's not going to be broken, how is this fundamentally different?
>
>> def func_loop():
>>     for x in 1,2,3:
>>         yield (lambda: x)
>
> Thats using a for-loop
> A 'for' in a comprehension carries a different intention, the matching names
> being merely coincidental.

So what you're saying is that these two are fundamentally different:

def unrolled():
    x = 1
    yield (lambda: x)
    x = 2
    yield (lambda: x)
    x = 3
    yield (lambda: x)

def loop():
    for x in 1,2,3:
        yield (lambda: x)

In other words, a loop should be implemented as a separate binding
each time, not a rebinding. That's an interesting point, and it does
make some sense; effectively, what you want is for the body of a for
loop to be a new scope, a unique scope every iteration of the loop,
and one that automatically closes over all variables in the parent
scope (including for assignments) except for the loop
iteration/counter variable.

That does make some sense, but it doesn't really fit Python's concept.
It would, however, fit a more C-like language, where locals are
declared (in Python, you'd have to put a whole lot of implicit
'nonlocal' statements at the top of the loop).

ChrisAg


From harrismh777 at gmail.com  Sat Mar 22 00:51:38 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 21 Mar 2014 23:51:38 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
Message-ID: <lgj4sp$7ed$1@speranza.aioe.org>

On 3/21/14 11:39 PM, Rustom Mody wrote:
> Given

> fl = [lambda y : x+y for x in [1,2,3]]

> It means:

> def rec(l):
>     if not l: return []
>     else:
>       x,ll = l[0],l[1:]
>       return [lambda y: x + y] + rec(ll)
>
> followed by
> fl = rec([1,2,3])

> Naturally a reasonable *implementation* would carry this *intention*
{snip}
> [But then I find Lisp and much of basic haskell natural and most of C++ not,
> so my views are likely prejudiced :-)


This discussion (the entire thread) comes up again and again over the 
years because python tries to be all things to all people, without much 
reason behind the motivation. I'm speaking of Lambda (filter, map, reduce).

Python is not Lisp. (I love Lisp too). Python is not Haskell (I love 
Haskell too).

Lambda is a problem, if only because it causes confusion. What's the 
problem?  Glad you asked. The constructs DO NOT work the way most people 
would expect them to, having limited knowledge of python!  I ran into 
this thing about seven years ago (when I was studying Haskell, and 
Scheme) and I wanted to see how "pure functional" python was (well, not 
at all really).

I can see uses for python's lambda.  But, honestly, I think python could 
deprecate its use and in five years just remove it from the language; 
along with filter, map, and reduce !

I'm just saying;

marcus



From harrismh777 at gmail.com  Sat Mar 22 00:59:34 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 21 Mar 2014 23:59:34 -0500
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <mailman.8380.1395461724.18130.python-list@python.org>
 <lgj3kd$4th$1@speranza.aioe.org>
 <mailman.8381.1395463585.18130.python-list@python.org>
Message-ID: <lgj5bl$89p$1@speranza.aioe.org>

On 3/21/14 11:46 PM, Chris Angelico wrote:
> (Side point: You have your 0d and your 0a backwards; the Unix line
> ending is U+000A, and the Windows default is U+000D U+000A.)

    Yeah, I know... smart apple.

> How are you going to make people change? What are you going to make
> them change to? Who controls this standard, and how do you convince
> all OSes to comply with it?

    Well, we're already doing this to some extent; baby steps.  Well, we 
have open document standards (evolving) and we have a really good sense 
for unicode (and python is being a genuine leader there) and the 
flat-file is just another open document (very simple no doubt), not 
different from a standards viewpoint than rft, odt, {whatever}; txt?

    My idea is that as we are morphing open document standards we need 
to keep the "flat-file" in mind too.  The ASCII ship has sailed too. 
Unicode is in, ASCII is out (for all intents and purposes) except at 
Microsoft---and its time to rethink what a "flat" unicode text file 
really is. That's all.

marcus


From rosuav at gmail.com  Sat Mar 22 01:05:29 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 16:05:29 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <532d15e8$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <532d15e8$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmrRH5F5kLtf1GaKJTmdeFVLCPb8ep6Ay-HdwA8bmA=uzQ@mail.gmail.com>

On Sat, Mar 22, 2014 at 3:47 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Now I'm not sure precisely how Haskell implements this trick, but it
> suggests to me that it creates a different closure each time around the
> loop of the comprehension. That could end up being very expensive.

It needn't be terribly expensive, if you make a "scope stack" or
"scope chain". Imagine, if you will, a system of scopes like this:

current_scope = None
class Scope:
    def __init__(self, *a, **kw):
        self.names = dict(*a, **kw)
        global current_scope
        self.parent = current_scope
        current_scope = self
    def __getitem__(self, name):
        try:
            return self.names[name]
        except KeyError:
            if self.parent is None: raise
            return self.parent[name]
    def __setitem__(self, name, value):
        self.names[name] = value
def exit_scope():
    global current_scope
    current_scope = current_scope.parent

Creating a new scope would be fairly cheap (and a lot more so if this
were implemented in C without the object overhead, of course). Lookups
would scan up through a series of namespaces, same as they currently
do (local, module, builtins), there'd just be more of them. And the
compiler could be smart enough to skip creating a scope if there are
no assignments. There'd need to be some handling in there for the
'nonlocal' keyword, but my expectation is that 'global' is handled by
retaining a reference to the current_scope at module level, and
starting the search there for a LOAD_GLOBAL.

Each iteration of the loop could begin with Scope() and end with
exit_scope(), and there you are, each iteration in its own closable
scope.

I'm not saying it would be a good thing to do - and it'd be a bad fit
for Python, I think, as I said in my other post - but it could be
done.

ChrisA


From tjreedy at udel.edu  Sat Mar 22 01:24:33 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sat, 22 Mar 2014 01:24:33 -0400
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <lgj3kd$4th$1@speranza.aioe.org>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <mailman.8380.1395461724.18130.python-list@python.org>
 <lgj3kd$4th$1@speranza.aioe.org>
Message-ID: <lgj6q9$i0d$1@ger.gmane.org>

On 3/22/2014 12:30 AM, Mark H Harris wrote:
> On 3/21/14 11:15 PM, Chris Angelico wrote:
>> It compounds. One reply makes for double spacing... two makes
>> quadruple, three means we have seven wasted lines between every pair
>> of real lines. That gets pretty annoying. And considering that most
>> people who reply without cleaning up the lines also keep the entire
>> quoted text (and usually top-post as well), this gets big fast.

Before Mark started asking people adjust to the foibles of gg, we used 
to get such posts. I refused to read them. I have not seen one lately, 
say maybe his nudging has had some positive effect.

>     Yes, I can see that readily/  I get it, it just seems that fixing it
> at the source (gg) is the answer;

I completely agree. However, Google seems immune to suggestions, 
including requests that it try to stop being a major source of spam posts.

 > because there will always be someone
> new to the list who is using gg because its part of their suite and
> because its convenient (I mean, that's why I tried to use it).

If I were in charge of the software used for this list, I would replace 
Mark with a custom addition to return mis-formated posts (more blank 
lines than not) with instructions on how to fix them. But I am not.

-- 
Terry Jan Reedy



From rustompmody at gmail.com  Sat Mar 22 01:26:26 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 21 Mar 2014 22:26:26 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8382.1395463877.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
Message-ID: <9edb4ea0-5faf-4369-8021-48afa9800a34@googlegroups.com>

On Saturday, March 22, 2014 10:21:13 AM UTC+5:30, Chris Angelico wrote:
> On Sat, Mar 22, 2014 at 3:39 PM, Rustom Mody wrote:
> >> So if that's not going to be broken, how is this fundamentally different?
> >> def func_loop():
> >>     for x in 1,2,3:
> >>         yield (lambda: x)
> > Thats using a for-loop
> > A 'for' in a comprehension carries a different intention, the matching names
> > being merely coincidental.

> So what you're saying is that these two are fundamentally different:

> def unrolled():
>     x = 1
>     yield (lambda: x)
>     x = 2
>     yield (lambda: x)
>     x = 3
>     yield (lambda: x)

> def loop():
>     for x in 1,2,3:
>         yield (lambda: x)

Well almost...

Except that the 'loop' I am talking of is one of

def loop():
     return [yield (lambda: x) for x in [1,2,3]]
or 
     return (yield (lambda: x) for x in [1,2,3])      
or just plain ol
     (lambda x:  for x in [1,2,3])

IOW loop is an imperative construct, comprehensions are declarative

Progressing through a loop in a sequential order is natural and to
be expected

Comprehensions being declarative, progressing through them
in some order is incidental.


> In other words, a loop should be implemented as a separate binding
> each time, not a rebinding. That's an interesting point, and it does
> make some sense; effectively, what you want is for the body of a for
> loop to be a new scope, a unique scope every iteration of the loop,
> and one that automatically closes over all variables in the parent
> scope (including for assignments) except for the loop
> iteration/counter variable.

> That does make some sense, but it doesn't really fit Python's concept.

Yes it does not fit in with imperative programming.

Its good to remember the history.
Haskell did not invent comprehensions

In programming, they started with Miranda where they were called
'ZF-expressions' after the Zermelo/Fraenkel of axiomatic set theory.

Because Russell's paradox had shaken the (intended) foundations of mathematics,
the way out (actually the one chosen by Zermelo and Fraenkel) was to
add a *comprehension axiom*

http://en.wikipedia.org/wiki/Zermelo%E2%80%93Fraenkel_set_theory#3._Axiom_schema_of_specification_.28also_called_the_axiom_schema_of_separation_or_of_restricted_comprehension.29

What this basically mandates is that set constructions like
{x | Pred(x) } are disqualified (called unrestricted comprehension)

Only
{x ? S | Pred(x) } is a valid.

IOW sets cannot be concocted out of the blue but only out of other sets.

Fast forward 50 years and what David Turner ? inventor of Miranda ?- realized 
is that if the programming language is sufficiently mathematical ? ie no
imperative constructs plus lazy evaluation, then comprehensions are
actually constructive enough to make make into programming constructs.

However as Mark Harris points out imperative and functional thinking styles
remain somewhat inconsistent with each other.


From rosuav at gmail.com  Sat Mar 22 01:32:06 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 22 Mar 2014 16:32:06 +1100
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <lgj6q9$i0d$1@ger.gmane.org>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <mailman.8380.1395461724.18130.python-list@python.org>
 <lgj3kd$4th$1@speranza.aioe.org> <lgj6q9$i0d$1@ger.gmane.org>
Message-ID: <CAPTjJmoLYVa5f-c3RFYEqZ-u1zDSULgOeuib20XdaPTG89FNSQ@mail.gmail.com>

On Sat, Mar 22, 2014 at 4:24 PM, Terry Reedy <tjreedy at udel.edu> wrote:
> If I were in charge of the software used for this list, I would replace Mark
> with a custom addition to return mis-formated posts (more blank lines than
> not) with instructions on how to fix them. But I am not.

I love how this makes it sound as if Mark is part of Mailman...

ChrisA


From rustompmody at gmail.com  Sat Mar 22 01:48:06 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 21 Mar 2014 22:48:06 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8382.1395463877.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
Message-ID: <81e23c17-05a0-420e-a7d3-b30210f7d71b@googlegroups.com>

On Saturday, March 22, 2014 10:21:13 AM UTC+5:30, Chris Angelico wrote:
> On Sat, Mar 22, 2014 at 3:39 PM, Rustom Mody  wrote:
> >> So if that's not going to be broken, how is this fundamentally different?
> >> def func_loop():
> >>     for x in 1,2,3:
> >>         yield (lambda: x)
> > Thats using a for-loop
> > A 'for' in a comprehension carries a different intention, the matching names
> > being merely coincidental.

> So what you're saying is that these two are fundamentally different:



> def unrolled():
>     x = 1
>     yield (lambda: x)
>     x = 2
>     yield (lambda: x)
>     x = 3
>     yield (lambda: x)

> def loop():
>     for x in 1,2,3:
>         yield (lambda: x)

Well almost
Except that the 'loop' I am talking of is one of

def loop():
     return [yield (lambda: x) for x in [1,2,3]]
or 
     return (yield (lambda: x) for x in [1,2,3])      
or just plain ol
     (lambda x:  for x in [1,2,3])

IOW loops is an imperative construct, comprehensions are declarative

Progressing through a loop in a sequential order is natural and to
be expected

Comprehensions being declarative, progressing through them
in some order is incidental.



> In other words, a loop should be implemented as a separate binding
> each time, not a rebinding. That's an interesting point, and it does
> make some sense; effectively, what you want is for the body of a for
> loop to be a new scope, a unique scope every iteration of the loop,
> and one that automatically closes over all variables in the parent
> scope (including for assignments) except for the loop
> iteration/counter variable.

> That does make some sense, but it doesn't really fit Python's concept.

Yes it does not fit in with imperative programming.

Its good to remember the history.
Haskell did not invent comprehensions

In programming, they started with Miranda where they were called
'ZF-expressions' after the Zermelo/Fraenkel of axiomatic set theory.

Because Russell's paradox had shaken the (intended) foundations of mathematics,
the way out (actually the one chosen by Zermelo and Fraenkel) was to
add a *comprehension axiom*

http://en.wikipedia.org/wiki/Zermelo%E2%80%93Fraenkel_set_theory#3._Axiom_schema_of_specification_.28also_called_the_axiom_schema_of_separation_or_of_restricted_comprehension.29

What this basically mandates is that set constructions like
{x | Pred(x) } are disqualified (called unrestricted comprehension)

Only
{x ? S | Pred(x) } is a valid.

IOW sets cannot be concoted out of the blue but only out of other sets.

FF 50 years and what David Turner ? inventor of Miranda ?- realized is that
if the programming language is sufficiently mathematical ? ie no
imperative constructs plus lazy evaluation, then comprehensions are
actually constructive enough to make make into programming constructs.

However as Mark Harris points out imperative and functional thinking styles
remain confusingly inconsistent.


From dieter at handshake.de  Sat Mar 22 03:20:05 2014
From: dieter at handshake.de (dieter)
Date: Sat, 22 Mar 2014 08:20:05 +0100
Subject: Problem with pickle and restarting a program
References: <cc656034-01c4-430c-84f0-a181cef6560a@googlegroups.com>
 <mailman.8292.1395303616.18130.python-list@python.org>
 <11a691c7-2842-4d3a-b355-1e44652d7590@googlegroups.com>
Message-ID: <87a9ci4s4a.fsf@handshake.de>

peace <abhishek1899 at gmail.com> writes:
> On Thursday, March 20, 2014 1:20:03 AM UTC-7, dieter wrote:
> ...
>> You may want to use debugging to determine what goes on in detail.
> ...
> I tried doing that. I still could not figure out what was wrong. Thank you.

Debugging is often not easy. An essential strategy is "divide and conquer":
i.e. you split the complete scenario into segments and analyse each
segment to find out where the bad thing happens.

Related to pickle, there is one point to lock at closely: where
you "dump" the data. Verify, that you are dumping the correct (expected) data.
If the data is not as you expect at that point, you must analyse
the first part (from where the data was produced up to the dumping point);
on the other hand, if the dumped data is correct, you would verify
that "load" restores this same data (this will be very likely the case)
and if it does why it became wrong afterward.



From chris at simplistix.co.uk  Fri Mar 21 14:34:07 2014
From: chris at simplistix.co.uk (Chris Withers)
Date: Fri, 21 Mar 2014 18:34:07 +0000
Subject: which async framework? - a summary
In-Reply-To: <20140313193634.3767ddfc@bigbox.christie.dr>
References: <531E22DF.7030709@simplistix.co.uk> <lflcha$2mf$1@ger.gmane.org>
 <531EC0E6.10402@simplistix.co.uk> <lfnotf$i2a$1@ger.gmane.org>
 <53224C89.5050503@simplistix.co.uk>
 <20140313193634.3767ddfc@bigbox.christie.dr>
Message-ID: <532C861F.7070504@simplistix.co.uk>

On 14/03/2014 00:36, Tim Chase wrote:
> On 2014-03-14 00:25, Chris Withers wrote:
>> I've been pleasantly surprised by the succinct, well reasoned and
>> respectful replies from each of the communities!
>
> As one who doesn't lurk on the other lists, is there a nice executive
> summary of their responses?

Well, of course, each person recommended their own framework.

The short version was:

- tornado is a web server, if you're not using it, the async stuff is 
better developed elsewhere

- asyncio is very new, not a lot of protocols out in the wild and not 
much battle testing

- twisted is been around the block a lot, huge amounts of support and an 
active, knowledgeable community. Can feel crufty and old in parts, mind

The community bit swung it for me, so I've opted for Twisted, if I ever 
get a chance to work on the project in question ;-)

Chris

-- 
Simplistix - Content Management, Batch Processing & Python Consulting
             - http://www.simplistix.co.uk


From wxjmfauth at gmail.com  Sat Mar 22 04:54:26 2014
From: wxjmfauth at gmail.com (wxjmfauth at gmail.com)
Date: Sat, 22 Mar 2014 01:54:26 -0700 (PDT)
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <lgj5bl$89p$1@speranza.aioe.org>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <mailman.8380.1395461724.18130.python-list@python.org>
 <lgj3kd$4th$1@speranza.aioe.org>
 <mailman.8381.1395463585.18130.python-list@python.org>
 <lgj5bl$89p$1@speranza.aioe.org>
Message-ID: <3d50db8b-2428-49ec-93af-7b0743bdfbe8@googlegroups.com>

Le samedi 22 mars 2014 05:59:34 UTC+1, Mark H. Harris a ?crit?:
> On 3/21/14 11:46 PM, Chris Angelico wrote:
> 
> > (Side point: You have your 0d and your 0a backwards; the Unix line
> 
> > ending is U+000A, and the Windows default is U+000D U+000A.)
> 
> 
> 
>     Yeah, I know... smart apple.
> 
> 
> 
> > How are you going to make people change? What are you going to make
> 
> > them change to? Who controls this standard, and how do you convince
> 
> > all OSes to comply with it?
> 
> 
> 
>     Well, we're already doing this to some extent; baby steps.  Well, we 
> 
> have open document standards (evolving) and we have a really good sense 
> 
> for unicode (and python is being a genuine leader there) and the 
> 
> flat-file is just another open document (very simple no doubt), not 
> 
> different from a standards viewpoint than rft, odt, {whatever}; txt?
> 
> 
> 
>     My idea is that as we are morphing open document standards we need 
> 
> to keep the "flat-file" in mind too.  The ASCII ship has sailed too. 
> 
> Unicode is in, ASCII is out (for all intents and purposes) except at 
> 
> Microsoft---and its time to rethink what a "flat" unicode text file 
> 
> really is. That's all.
> 
> 

No offense. A good start would be to understand "unicode"
instead of bashing MS.

jmf


From ian.g.kelly at gmail.com  Sat Mar 22 05:09:56 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 22 Mar 2014 03:09:56 -0600
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
Message-ID: <CALwzid=i-NbZPmAq9suMwvgGCPvu_9=sxgPVf=Mk9aBGXRRtfg@mail.gmail.com>

On Fri, Mar 21, 2014 at 8:06 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> Two: A comprehension variable is not bound but reassigned across the
> comprehension. This problem remains in python3 and causes weird behavior when
> lambdas are put in a comprehension

Because Python as a language only has the concept of assignment, not
binding.  I think it would be weird and confusing if variables worked
this way in comprehensions and nowhere else.

> >>> fl = [lambda y : x+y for x in [1,2,3]]
> >>> [fl[i](2) for i in [0,1,2]]
> [5, 5, 5]

You can get the desired effect by adding a layer of indirection:

>>> fl = [(lambda x: lambda y: x+y)(x) for x in [1,2,3]]
>>> [f(2) for f in fl]
[3, 4, 5]

If that's too ugly then give the wrapper a proper name:

>>> def make_function(x):
...     return lambda y: x+y
...
>>> fl = [make_function(x) for x in [1,2,3]]
>>> [f(2) for f in fl]
[3, 4, 5]

There is also the default argument trick:

>>> fl = [lambda y, *, x=x: x+y for x in [1,2,3]]
>>> [f(2) for f in fl]
[3, 4, 5]


From steve+comp.lang.python at pearwood.info  Sat Mar 22 05:46:01 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 22 Mar 2014 09:46:01 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
Message-ID: <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Fri, 21 Mar 2014 23:51:38 -0500, Mark H Harris wrote:

> Lambda is a problem, if only because it causes confusion. What's the
> problem?  Glad you asked. The constructs DO NOT work the way most people
> would expect them to, having limited knowledge of python!

Why is that a problem? Would you consider it a problem that people who 
don't understand BASIC can't understand BASIC? ("I don't get the 
difference between GOTO and GOSUB. Obviously GOSUB is a problem and 
should be throw out.") Do you think that the fact that people who have 
never used a TI-89 calculator before may have trouble used a TI-89 
calculator means that TI-89 calculators are "a problem"? (I've taught 
school children who didn't know how to use their calculator.)

The problem is ignorance, not the calculator, and not lambda.

You've told us that "most people" (which people? dentists? lawyers? 
illiterate tribesmen from the Amazon? professional programmers?) are 
surprised by lamba's behaviour, but you haven't actually told us what 
behaviour is surprising, or what "most people" expect lambda to do. 
Perhaps you ought to?


> I ran into
> this thing about seven years ago (when I was studying Haskell, and
> Scheme) and I wanted to see how "pure functional" python was (well, not
> at all really).

Python is not a pure functional language, but you can write functional 
code in it. If you want a pure functional language, you know where to 
find one.

(I wonder whether, say, Haskell has the people coming along and demanding 
that it should become more like Python?)


> I can see uses for python's lambda.  But, honestly, I think python could
> deprecate its use and in five years just remove it from the language;
> along with filter, map, and reduce !

Python could deprecate many things. It would make Python a worse language.

By the way, are you aware that lambda is *identical* to def except for 
three things?

- lambda is an expression, not a statement like def;

- the body of a function created with lambda is limited to a 
  single expression, not a block;

- the function object created with lambda has a generic name.


So unless the surprising behaviour about lambda that you're about to tell 
us about relates to one of those three things, I *guarantee* that 
functions created with def have the same surprising behaviour.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Sat Mar 22 05:50:55 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 22 Mar 2014 09:50:55 GMT
Subject: Python MSI not installing, log file showing name of a
 Viatnemese communist revolutionary
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <mailman.8380.1395461724.18130.python-list@python.org>
 <lgj3kd$4th$1@speranza.aioe.org>
 <mailman.8384.1395465895.18130.python-list@python.org>
Message-ID: <532d5cfe$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sat, 22 Mar 2014 01:24:33 -0400, Terry Reedy wrote:

> On 3/22/2014 12:30 AM, Mark H Harris wrote:
>> On 3/21/14 11:15 PM, Chris Angelico wrote:
>>> It compounds. One reply makes for double spacing... two makes
>>> quadruple, three means we have seven wasted lines between every pair
>>> of real lines. That gets pretty annoying. And considering that most
>>> people who reply without cleaning up the lines also keep the entire
>>> quoted text (and usually top-post as well), this gets big fast.
> 
> Before Mark started asking people adjust to the foibles of gg, we used
> to get such posts. I refused to read them. I have not seen one lately,

Luck you. I see them quite frequently.


> say maybe his nudging has had some positive effect.
> 
>>     Yes, I can see that readily/  I get it, it just seems that fixing
>>     it
>> at the source (gg) is the answer;
> 
> I completely agree. However, Google seems immune to suggestions,
> including requests that it try to stop being a major source of spam
> posts.

Remember, we are not Google's customers. We are Google's product. The 
customers are the advertisers.

[...]
> If I were in charge of the software used for this list, I would replace
> Mark with a custom addition to return mis-formated posts (more blank
> lines than not) with instructions on how to fix them. But I am not.

Wouldn't it be less obnoxious and more useful to pass the posts through a 
filter that deletes the annoying blank lines?



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From tjreedy at udel.edu  Sat Mar 22 06:14:16 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sat, 22 Mar 2014 06:14:16 -0400
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <532d5cfe$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <mailman.8380.1395461724.18130.python-list@python.org>
 <lgj3kd$4th$1@speranza.aioe.org>
 <mailman.8384.1395465895.18130.python-list@python.org>
 <532d5cfe$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgjnpg$54n$1@ger.gmane.org>

On 3/22/2014 5:50 AM, Steven D'Aprano wrote:
> On Sat, 22 Mar 2014 01:24:33 -0400, Terry Reedy wrote:

>> If I were in charge of the software used for this list, I would replace
>> Mark with a custom addition to return mis-formated posts (more blank
>> lines than not) with instructions on how to fix them. But I am not.
>
> Wouldn't it be less obnoxious and more useful to pass the posts through a
> filter that deletes the annoying blank lines?

I have thought of that too, and may have suggested it. It would be 
slightly harder as a decision would be required as to which to delete.

-- 
Terry Jan Reedy



From greg.ewing at canterbury.ac.nz  Sat Mar 22 06:19:58 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Sat, 22 Mar 2014 23:19:58 +1300
Subject: Github down?
In-Reply-To: <lgin4u$qsv$1@dont-email.me>
References: <CANc-5Uxf71ZEOtqHzYbgB3Gg5jwQM-=oYefdKL2bq=En+P1jTQ@mail.gmail.com>	<CACwCsY7-mVjdvGdhN5VDohp2Sjujo3t=xUkN6ZwhXuFp1A9YdQ@mail.gmail.com>	<CANc-5Uw0r=CNvj1Q7dfzqLGDp_f+3dZwiQtaKsQXjhbK2HnnZQ@mail.gmail.com>	<mailman.8356.1395409923.18130.python-list@python.org>
 <lgin4u$qsv$1@dont-email.me>
Message-ID: <bp56ecF6fe2U1@mid.individual.net>

Dan Sommers wrote:
> On Fri, 21 Mar 2014 14:51:54 +0100, Chris ?Kwpolska? Warrick wrote:
> 
>>(though GitHub could qualify as social media for some?)
> 
> +1 QOTW

https://xkcd.com/624/


From marko at pacujo.net  Sat Mar 22 06:24:47 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 22 Mar 2014 12:24:47 +0200
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <532d15e8$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87zjki4jkg.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> This makes perfect sense: by the time you call the functions, the name x 
> has been rebound to the value 3.

> [...]

> Now I'm not sure precisely how Haskell implements this trick, but it
> suggests to me that it creates a different closure each time around
> the loop of the comprehension. That could end up being very expensive.

Haskell does not rebind variables. I guess Haskell simply physically
substitutes object references for each syntactic occurrence of a
variable.

If Python worked analogously, the following loop:

   for i, x in enumerate([1, 2, 3]):
       f[i] = lambda y: x + y

would unroll as follows:

   f[0] = lambda y: 1 + y
   f[1] = lambda y: 2 + y
   f[2] = lambda y: 3 + y

That is actually how classic lambda calculus does it. Variables are
substituted, not "bound" or "assigned". They are syntactic slots. There
is no heap, there is no stack, there is no memory apart from the
expression itself.


Marko


From marko at pacujo.net  Sat Mar 22 06:30:28 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 22 Mar 2014 12:30:28 +0200
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8388.1395479446.18130.python-list@python.org>
Message-ID: <87vbv64jaz.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> You can get the desired effect by adding a layer of indirection:
>
>>>> fl = [(lambda x: lambda y: x+y)(x) for x in [1,2,3]]

A trick to remember! Variable lifetime reduction by function invocation.


Marko


From breamoreboy at yahoo.co.uk  Sat Mar 22 06:40:49 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 22 Mar 2014 10:40:49 +0000
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
Message-ID: <lgjpb8$gtg$1@ger.gmane.org>

On 22/03/2014 02:06, Rustom Mody wrote:
>
> The same in haskell:
>
> Prelude> let fl = [\ y -> x + y | x <- [1,2,3]]
> Prelude> [(fl!!i) 0 | i<- [0,1,2]]
> [1,2,3]
>

My really big complaint about Python is that it's nothing like CORAL 66. 
  I think I'll raise this on python ideas in an attempt to get this 
glaring deficiency corrected.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
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From breamoreboy at yahoo.co.uk  Sat Mar 22 06:51:05 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 22 Mar 2014 10:51:05 +0000
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <lgj1pd$10g$1@speranza.aioe.org>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
Message-ID: <lgjpui$qr4$1@ger.gmane.org>

On 22/03/2014 03:58, Mark H Harris wrote:
> On 3/21/14 5:44 PM, Mark Lawrence wrote:
>> I'm pleased to see that you have answers. In return would you either use
>> the mailing list https://mail.python.org/mailman/listinfo/python-list or
>> read and action this https://wiki.python.org/moin/GoogleGroupsPython to
>> prevent us seeing double line spacing and single line paragraphs, thanks.
>
> I perceive that this is your singular pet peeve, or, you were elected by
> the python community some time ago to police the line-end problem ?
>

It's a pet peeve as:-

a) trying to read something that's the fourth level of reply or higher 
to the original gets to be almost impossible as it's all white space and 
no substance.

b) better tools exist

c) the work around is shown on the Python wiki, not on the crappy, bug 
ridden gg site itself.

Wow, it's like a sauna in here :)

I doubt that the Python community would elect me to do anything.  Anyhow 
I start my new job in the diplomatic corp next week.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From breamoreboy at yahoo.co.uk  Sat Mar 22 06:54:38 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 22 Mar 2014 10:54:38 +0000
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <3d50db8b-2428-49ec-93af-7b0743bdfbe8@googlegroups.com>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <mailman.8380.1395461724.18130.python-list@python.org>
 <lgj3kd$4th$1@speranza.aioe.org>
 <mailman.8381.1395463585.18130.python-list@python.org>
 <lgj5bl$89p$1@speranza.aioe.org>
 <3d50db8b-2428-49ec-93af-7b0743bdfbe8@googlegroups.com>
Message-ID: <lgjq56$qr4$2@ger.gmane.org>

On 22/03/2014 08:54, wxjmfauth at gmail.com wrote:
> Le samedi 22 mars 2014 05:59:34 UTC+1, Mark H. Harris a ?crit :
>> On 3/21/14 11:46 PM, Chris Angelico wrote:
>>
>>> (Side point: You have your 0d and your 0a backwards; the Unix line
>>
>>> ending is U+000A, and the Windows default is U+000D U+000A.)
>>
>>
>>
>>      Yeah, I know... smart apple.
>>
>>
>>
>>> How are you going to make people change? What are you going to make
>>
>>> them change to? Who controls this standard, and how do you convince
>>
>>> all OSes to comply with it?
>>
>>
>>
>>      Well, we're already doing this to some extent; baby steps.  Well, we
>>
>> have open document standards (evolving) and we have a really good sense
>>
>> for unicode (and python is being a genuine leader there) and the
>>
>> flat-file is just another open document (very simple no doubt), not
>>
>> different from a standards viewpoint than rft, odt, {whatever}; txt?
>>
>>
>>
>>      My idea is that as we are morphing open document standards we need
>>
>> to keep the "flat-file" in mind too.  The ASCII ship has sailed too.
>>
>> Unicode is in, ASCII is out (for all intents and purposes) except at
>>
>> Microsoft---and its time to rethink what a "flat" unicode text file
>>
>> really is. That's all.
>>
>>
>
> No offense. A good start would be to understand "unicode"
> instead of bashing MS.
>
> jmf
>

How apt given how this thread has moved :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ram.rachum at gmail.com  Sat Mar 22 06:57:25 2014
From: ram.rachum at gmail.com (cool-RR)
Date: Sat, 22 Mar 2014 03:57:25 -0700 (PDT)
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <mailman.8376.1395452380.18130.python-list@python.org>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <793ecef5-2025-4714-a6a4-cff13c93f45d@googlegroups.com>
 <mailman.8376.1395452380.18130.python-list@python.org>
Message-ID: <869d5d75-1641-4c81-8af5-f1ef40e55a9e@googlegroups.com>

On Saturday, March 22, 2014 3:39:21 AM UTC+2, Terry Reedy wrote:
> Does your .b2 install work? Can you delete it thru the programs list?

I uninstalled it before this entire adventure.


From teddybubu at gmail.com  Sat Mar 22 07:21:30 2014
From: teddybubu at gmail.com (teddybubu at gmail.com)
Date: Sat, 22 Mar 2014 04:21:30 -0700 (PDT)
Subject: help with for loop----python 2.7.2
Message-ID: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>

I am trying to get all the element data from the rss below.
The only thing I am pulling is the first element.
I don't understand why the for loop does not go through the entire rss.
Here is my code....


try:
    from urllib2 import urlopen
except ImportError:
    from urllib.request import urlopen 

from bs4 import BeautifulSoup 

soup = BeautifulSoup(urlopen('http://bl.ocks.org/mbostock.rss'))
#print soup.find_all('item')
#print (soup)

for item in soup.find_all('item'):
#for item in soup:    
    title = soup.find('title').text    
    link = soup.find('link').text
    item = soup.find('item').text
    print item
    print title
    print link


From laguna-mc at mail.com  Sat Mar 22 07:48:36 2014
From: laguna-mc at mail.com (laguna-mc at mail.com)
Date: Sat, 22 Mar 2014 07:48:36 -0400
Subject: Installing ssdeep on Portable Python /advice
Message-ID: <20140322114836.177130@gmx.com>

http://ssdeep.sourceforge.net/usage.html

the installation described in aboved document is for Linux only.
Well, I need experiment and see errors.

Regards,


> ----- Original Message -----
> From: Mark H Harris
> Sent: 03/22/14 05:32 AM
> To: python-list at python.org
> Subject: Re: Installing ssdeep on Portable Python /advice
> 
> On 3/21/14 9:51 PM, Mark H Harris wrote:
> > On 3/20/14 7:16 PM, laguna-mc at mail.com wrote:
> 
> >> $ tar -zxvf ssdeep-2.10.tar.gz
> >> $ cd ssdeep-2.10&& ./configure&& make&& sudo make install
> 
> >> I need install it on PortablePython for Windows, so it's not
> >> clear how to make this: where should be placed ssdeep Windows
> >> binary files, that Python application can found it?
> 
> > It is strongly recommended that ssdeep be run on windows from
> > precompiled binaries. Building from sources is not recommended because
> > of dependencies and environment...
> 
> > Google is our frined;
> 
> > http://ssdeep.sourceforge.net/usage.html
> 
> 
> Actually, I restated that wrong. The doc says that building from sources 
> on windows is NOT supported.
> 
> marcus
> -- 
> https://mail.python.org/mailman/listinfo/python-list



From ian.g.kelly at gmail.com  Sat Mar 22 08:00:47 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 22 Mar 2014 06:00:47 -0600
Subject: help with for loop----python 2.7.2
In-Reply-To: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
References: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
Message-ID: <CALwzid=__zqn_Q7W+cNwgP_Q=Dz1mh87foY4y190MMEAUHGVTg@mail.gmail.com>

On Sat, Mar 22, 2014 at 5:21 AM,  <teddybubu at gmail.com> wrote:
> I am trying to get all the element data from the rss below.
> The only thing I am pulling is the first element.
> I don't understand why the for loop does not go through the entire rss.
> Here is my code....

[SNIP]

> for item in soup.find_all('item'):
> #for item in soup:
>     title = soup.find('title').text
>     link = soup.find('link').text
>     item = soup.find('item').text

The three find method calls in the for loop are searching from the
document root (the "soup" variable), not from the item you're
currently iterating at.  Try changing these to calls of item.find. And
note that calling one of the results "item" will replace the loop
variable.  That won't affect the iteration, but it's bad practice to
refer to two different things by the same local name.


From jabba.laci at gmail.com  Sat Mar 22 08:40:31 2014
From: jabba.laci at gmail.com (Jabba Laci)
Date: Sat, 22 Mar 2014 13:40:31 +0100
Subject: terminate a program gracefully from a thread
Message-ID: <CAOuJsMny-DV2kLS2EU1=FtHr6zkMH__-Q-2z8_-wnaSKmap8iA@mail.gmail.com>

Hi,

I have a script (see below) that I want to terminate after X seconds.
The main loop of the program is waiting for user input.
The program enters the main loop and I try to shut down the program
after X seconds from a thread but I can't figure out how to do it. The
program should also do some cleanup before termination, so the shut
down must be graceful.

The code below is a simplified version. The whole idea is the
following: I have a script that has grown quite big over time. It
needs to read several data files, so when I start it for the first
time, it takes about 3-4 seconds to launch. The next start is much
faster since, I guess, the OS has done some caching. I use this script
a lot and the first slow launch bothers me. My idea: after booting, I
want to start the script in the background in suicide mode. OS does
the caching, so when I need it, it starts quickly.

See the code below with comments.

Thanks,

Laszlo

===============

import atexit
import sys
import time
from threading import Thread
import os

def suicide(wait):
    time.sleep(wait)
    print("should exit now...")
    sys.exit()      # exits this thread but not the main thread
#    os._exit(0)    # no cleanup with this :(

def cleanup():
    # I want it to run before termination.
    print("cleaning up...")

def main():
    Thread(target=suicide, kwargs={'wait': 3}).start()
    #
    while True:
        try:
            inp = raw_input("in> ")
            print(inp)
        except (KeyboardInterrupt, EOFError):
            print()
            sys.exit()

#####

if __name__ == "__main__":
    atexit.register(cleanup)
    main()


From davea at davea.name  Sat Mar 22 09:18:52 2014
From: davea at davea.name (Dave Angel)
Date: Sat, 22 Mar 2014 09:18:52 -0400 (EDT)
Subject: terminate a program gracefully from a thread
References: <CAOuJsMny-DV2kLS2EU1=FtHr6zkMH__-Q-2z8_-wnaSKmap8iA@mail.gmail.com>
Message-ID: <lgk2ad$end$1@ger.gmane.org>

 Jabba Laci <jabba.laci at gmail.com> Wrote in message:
> Hi,
> 
> I have a script (see below) that I want to terminate after X seconds.
> The main loop of the program is waiting for user input.
> The program enters the main loop and I try to shut down the program
> after X seconds from a thread but I can't figure out how to do it. The
> program should also do some cleanup before termination, so the shut
> down must be graceful.
> 
> The code below is a simplified version. The whole idea is the
> following: I have a script that has grown quite big over time. It
> needs to read several data files, so when I start it for the first
> time, it takes about 3-4 seconds to launch. The next start is much
> faster since, I guess, the OS has done some caching. I use this script
> a lot and the first slow launch bothers me. My idea: after booting, I
> want to start the script in the background in suicide mode. OS does
> the caching, so when I need it, it starts quickly.
> 

You need a flag to indicate that a particular invocation is the
 dummy one (background). So use that same flag either to suppress
 starting the thread,  or to avoid the unwanted raw_input.
 

If you had no blocking I/o, you could use a simple global to
 notify all the threads. Or use a signal to abort the main thread
 if it's stuck in raw_input. 

Alternatively,  rethink the need to preload at boot time.  Any
 caching the OS does is likely to only last a few minutes, 
 depending on load. So maybe you can make the real load seem to be
 quicker by displaying the gui right away,  but doing the
 time-consuming part in a thread. 
 
-- 
DaveA



From jabba.laci at gmail.com  Sat Mar 22 09:19:44 2014
From: jabba.laci at gmail.com (Jabba Laci)
Date: Sat, 22 Mar 2014 14:19:44 +0100
Subject: terminate a program gracefully from a thread
In-Reply-To: <lgk2ad$end$1@ger.gmane.org>
References: <CAOuJsMny-DV2kLS2EU1=FtHr6zkMH__-Q-2z8_-wnaSKmap8iA@mail.gmail.com>
 <lgk2ad$end$1@ger.gmane.org>
Message-ID: <CAOuJsMnC-eJMYxomQXK+_dyCB=_O1w87cRMac02XPYYdD4Dc6Q@mail.gmail.com>

> You need a flag to indicate that a particular invocation is the
>  dummy one (background). So use that same flag either to suppress
>  starting the thread,  or to avoid the unwanted raw_input.
>
> Alternatively,  rethink the need to preload at boot time.  Any
>  caching the OS does is likely to only last a few minutes,
>  depending on load. So maybe you can make the real load seem to be
>  quicker by displaying the gui right away,  but doing the
>  time-consuming part in a thread.

Hi,

Thanks for the idea. Right, if it's started in suicide mode, then
there is no need to enter the raw_input.

Thanks,

Laszlo


From rosuav at gmail.com  Sat Mar 22 09:44:51 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 23 Mar 2014 00:44:51 +1100
Subject: terminate a program gracefully from a thread
In-Reply-To: <lgk2ad$end$1@ger.gmane.org>
References: <CAOuJsMny-DV2kLS2EU1=FtHr6zkMH__-Q-2z8_-wnaSKmap8iA@mail.gmail.com>
 <lgk2ad$end$1@ger.gmane.org>
Message-ID: <CAPTjJmofex4LXsacM8+z7XQfOiuRcSjcFs_b-YaY2SN9KQmENQ@mail.gmail.com>

On Sun, Mar 23, 2014 at 12:18 AM, Dave Angel <davea at davea.name> wrote:
> Alternatively,  rethink the need to preload at boot time.  Any
>  caching the OS does is likely to only last a few minutes,
>  depending on load. So maybe you can make the real load seem to be
>  quicker by displaying the gui right away,  but doing the
>  time-consuming part in a thread.

I second this motion. Don't preload stuff on boot like that; if you
want the data preloaded, actually load the program and keep it
running. Depending on the OS/FS cache like that is a bit better than
what seems to proliferate on Windows ("MS Office fast-load" being one
of the worst offenders), where there's this constant fight between
boot time and program load time, with RAM usage going nuts in between.
By (ab)using the disk cache like this, you make your cache work
beautifully until some app actually needs all that RAM, and then your
cache will be dropped; which is a good thing for the system, but it
means you'll have completely wasted the loading effort. Much better to
be more explicit about it, and probably just accept that first startup
is slower.

ChrisA


From vikram.denizen at gmail.com  Sat Mar 22 09:41:14 2014
From: vikram.denizen at gmail.com (vikram.denizen at gmail.com)
Date: Sat, 22 Mar 2014 06:41:14 -0700 (PDT)
Subject: newbie - Does IDLE care about sitecustomize.py?
In-Reply-To: <1132151829.600244.9210@g14g2000cwa.googlegroups.com>
References: <1132151829.600244.9210@g14g2000cwa.googlegroups.com>
Message-ID: <f10f31d6-a28a-4327-9468-d2c1727b474c@googlegroups.com>

Could you figure this out?

On Wednesday, November 16, 2005 10:37:09 PM UTC+8, bobu... at yahoo.com wrote:
> I have the following test script in the file customize.py
> 
> # C:\Python24\Lib\site-packages\sitecustomize.py
> print "test text from sitecustomize"
> 
> If start Python from command prompt I get
> 
> C:\Python24>python
> test in sitecustomize
> Python 2.4.1 (#65, Mar 30 2005, 09:13:57) [MSC v.1310 32 bit (Intel)]
> on win32
> Type "help", "copyright", "credits" or "license" for more information.
> 
> which shows that sitecustomize.py works
> 
> 
> Now if I start IDLE I only get
> 
> IDLE 1.1.1
> >>>
> 
> which shows that that IDLE doesn't care about sitecustomize.py
> 
> Am I missing something or how do you customize if you are using IDLE?



From rosuav at gmail.com  Sat Mar 22 09:57:30 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 23 Mar 2014 00:57:30 +1100
Subject: newbie - Does IDLE care about sitecustomize.py?
In-Reply-To: <f10f31d6-a28a-4327-9468-d2c1727b474c@googlegroups.com>
References: <1132151829.600244.9210@g14g2000cwa.googlegroups.com>
 <f10f31d6-a28a-4327-9468-d2c1727b474c@googlegroups.com>
Message-ID: <CAPTjJmog0eJ7=OXt9yZ1AFghtscPjEsv3gTjKz6R397VzN8XOA@mail.gmail.com>

On Sun, Mar 23, 2014 at 12:41 AM,  <vikram.denizen at gmail.com> wrote:
> Could you figure this out?
>
> On Wednesday, November 16, 2005 10:37:09 PM UTC+8, bobu... at yahoo.com wrote:
>> [ chomp ]

You're responding to a decade-old post, you're posting from Google
Groups, and you haven't added any information to the thread at all.
The original post was talking about Python 2.4, which is well and
truly out of support (unless you're running RHEL5), so the very first
thing you should do is see if there's still a corresponding issue with
a current version of Python. The next thing to do is to make sure you
don't offend with form (always offend people with substance, it's more
satisfying), so either don't use Google Groups, or clean up what you
post so it comes out looking correct. And following the standard
interleaved style, rather than top-posting, will also help.

ChrisA


From kjakupak at gmail.com  Sat Mar 22 09:56:05 2014
From: kjakupak at gmail.com (kjakupak at gmail.com)
Date: Sat, 22 Mar 2014 06:56:05 -0700 (PDT)
Subject: User prompt as file to read
Message-ID: <83317185-701d-4218-a748-00b75b51843c@googlegroups.com>

I'm trying to create a program that will prompt the user for a list of text files to read from, then read those text files and build a dictionary of all the unique words found. Then finally put those unique words into another file and make it alphabetical order.

What I've got:

import string

s = input("Enter a file name: ") + ".txt"
filepath = "I:\\" + s

# remove all punctuation marks and make lower case
s_nopunct = "".join(c for c in s if c not in string.punctuation).lower()

# convert to a sorted list of unique words via set comprehension
list_unique = sorted(list({word for word in s_nopunct.split()}))

print("\nSorted list of unique words in sentence:")
print(list_unique)

with open("C:\\Users\\Desktop\\words.dat", "w") as f:
    for x in list_unique:
        f.write(x + "\n")

I need help making it so that the user is prompted to enter at least 3 files.
And also, I tried making those unique words to write to another file (I got it that far), but how do I make it more of an arbitrary path (rather than the C:\Users etc) since I need it so that anyone can run that program and write/find to that file.


From ian.g.kelly at gmail.com  Sat Mar 22 10:22:28 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 22 Mar 2014 08:22:28 -0600
Subject: Python - Caeser Cipher Not Giving Right Output
In-Reply-To: <lggdbi$ku6$1@ger.gmane.org>
References: <7eee0f2b-0d5f-409e-ae4e-8c9c1af31d74@googlegroups.com>
 <mailman.8341.1395371543.18130.python-list@python.org>
 <bda05813-d186-41ea-a40d-5d36f90a8fed@googlegroups.com>
 <lggdbi$ku6$1@ger.gmane.org>
Message-ID: <CALwzidkDtCo2aGp=Ae1e=X8veFi5TSdhFBin0i+Be-yBsMNR7g@mail.gmail.com>

On Mar 20, 2014 9:59 PM, "Dave Angel" <davea at davea.name> wrote:
>
>  dtran.ru at gmail.com Wrote in message:
> > And I was wondering how I would add the partenthesis because I tried:
> >
> > return numtochar(c1 + c2 (%26)) and it gave me an error.
>
> Please help us to help you by actually showing the traceback.
>  Doesn't matter in this case, but...
>
> What order do you want the add and the modulo to happen?  Use the
>  parentheses to say so.

Ah, but he did. x = y + z (mod m) is a perfectly well-formed math equation.
Not the OP's fault if it doesn't work that way in Python.
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From davea at davea.name  Sat Mar 22 10:34:25 2014
From: davea at davea.name (Dave Angel)
Date: Sat, 22 Mar 2014 10:34:25 -0400 (EDT)
Subject: User prompt as file to read
References: <83317185-701d-4218-a748-00b75b51843c@googlegroups.com>
Message-ID: <lgk6o2$t8u$1@ger.gmane.org>

 kjakupak at gmail.com Wrote in message:
> I'm trying to create a program that will prompt the user for a list of text files to read from, then read those text files and build a dictionary of all the unique words found. Then finally put those unique words into another file and make it alphabetical order.

Specify python version and os.  I assume python 3 and Windows. 

> 
> What I've got:
> 
> import string
> 
> s = input("Enter a file name: ") + ".txt"
> filepath = "I:\\" + s

So you've got a filename.  You're not using it for anything.
 Where's your open? Where's your read or readline?
 

> 
> # remove all punctuation marks and make lower case
> s_nopunct = "".join(c for c in s if c not in string.punctuation).lower()

Are you sure you want a single string nearly the total size of
 your 3 files? Could be huge. Might be better to do it
 incrementally. 

It's a lot safer to include the characters you want,  instead of
 excluding some of the ones you don't.  And many valid words
 contain punctuation such as apostrophe. 

> 
> # convert to a sorted list of unique words via set comprehension
> list_unique = sorted(list({word for word in s_nopunct.split()}))
> 


> print("\nSorted list of unique words in sentence:")
> print(list_unique)
> 
> with open("C:\\Users\\Desktop\\words.dat", "w") as f:
>     for x in list_unique:
>         f.write(x + "\n")
> 
> I need help making it so that the user is prompted to enter at least 3 files.

Need a while loop for that. 

> And also, I tried making those unique words to write to another file (I got it that far), but how do I make it more of an arbitrary path (rather than the C:\Users etc) since I need it so that anyone can run that program and write/find to that file.
> 

That could be another input, or it could be a command line
 parameter.  Your choice. 

-- 
DaveA



From steve+comp.lang.python at pearwood.info  Sat Mar 22 10:50:47 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 22 Mar 2014 14:50:47 GMT
Subject: Python MSI not installing, log file showing name of a
 Viatnemese communist revolutionary
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
Message-ID: <532da347$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Fri, 21 Mar 2014 22:58:37 -0500, Mark H Harris wrote:

> I notice (since moving my stuff to Thunderbird two weeks back) the
> double spacing you keep squawking about, but I don't find it the big
> nuisance you're talking about; ok, so we have to scroll a bit further.

It's not the scrolling that interferes

with readability, it's the interruption

to the flow of text by having excess 

blank lines within a paragraph of text.



> I am honestly convinced that this might even be a python problem.  More
> likely than not, gg is written in python, and this is the goofy line-end
> character problem we have to deal with when we read lines in python.

Well, that's certainly a novel idea. Why you think that Google Groups is 
written in Python? Does every post from GG end with "Powered By Python"?


> Why do we suck in the new-line character as though it were part of the
> line?  

Because it is the only sensible way to handle it. If you don't, then 
there is no way to distinguish between a file that ends with a newline 
and one which doesn't.


> This is asinine behavior.  The new-line is a "file" delimiter
> character and NOT intended to be part of the line.

Line endings are terminators: they end the line. Whether you consider the 
terminator part of the line or not is a matter of opinion (is the cover 
of a book part of the book?) but consider this:

    If you say that the end of lines are *not* part of the line, then 
    that implies that some parts of the file are not inside any line 
    at all. And that would be just weird.


> Thinking this through a bit

Yes, that helps :-)


> I've noticed that a blank line comes back
> with a '\n'  which differentiates it from file end which comes back
> "without" the new-line.  So, it appears that python is using the
> new-line character (or lack there-of) to have meaning which the new=line
> in a unix file was never suppose to carry.

I don't understand what meaning you are referring to here. Blank lines 
comes back as a \n because a blank line *is* a \n with nothing before it. 
Python isn't doing anything funny here, at least not on Linux. If you 
open a text editor, and type:

spam ENTER ENTER ENTER ENTER eggs ENTER

(where ENTER means to hit the Enter key, not the letters E N T E R) and 
then save, your editor will show the words "spam" and "eggs" separated by 
three blank lines. If you open that file in a hex editor, you will see 
something like:

73 70 61 6d 0a 0a 0a 0a  65 67 67 73 0a

Notice the four 0a bytes in a row? That gives you three blank lines. 
Python is no adding any extra newlines or putting them where they aren't, 
so I don't really understand what point you're trying to make here.


 
> If python would just return EOF like every other language at file end,
> and a test line without '\n' tacked to the end of it, this little snag
> with gg would probably go away.  What say you?

There is no evidence that Google Group's difficulty is because of Python. 
More likely it is related to the translation between "rich text" 
formatted using HTML, and plain text.

By the way, Python *does* return EOF at the end of the file. It is just 
that EOF in Python is spelled "the empty string" instead of some other 
special value. Both Ruby and Lua behave like Python, returning the empty 
string on end of file:

steve at orac:~$ irb
irb(main):001:0> f = File.open('/tmp/io.txt')
=> #<File:/tmp/io.txt>
irb(main):002:0> f.read()
=> "hello"
irb(main):003:0> f.read()
=> ""


[steve at ando ~]$ lua
Lua 5.1.4  Copyright (C) 1994-2008 Lua.org, PUC-Rio
> fp = io.open('/tmp/io.txt', 'r')
> print(fp:read("*all"))
hello
> print(fp:read("*all"))

>


Similarly, Rust returns None:
http://static.rust-lang.org/doc/0.9/std/io/trait.Reader.html#tymethod.read

And Java's java.io.BufferedReader is also similar, returning null.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Sat Mar 22 11:09:20 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 23 Mar 2014 02:09:20 +1100
Subject: Python MSI not installing, log file showing name of a Viatnemese
 communist revolutionary
In-Reply-To: <532da347$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <532da347$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmpEhO5rxwAvtYEfqJ10WK658O0kRBGmy1jB9kYZYN-hRQ@mail.gmail.com>

On Sun, Mar 23, 2014 at 1:50 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Line endings are terminators: they end the line. Whether you consider the
> terminator part of the line or not is a matter of opinion (is the cover
> of a book part of the book?) but consider this:
>
>     If you say that the end of lines are *not* part of the line, then
>     that implies that some parts of the file are not inside any line
>     at all. And that would be just weird.

Not so weird IMO. A file is not a concatenation of lines; it is a
stream of bytes. Now, if you ask Python to read you 512 bytes from a
binary file, and then ask for another 512 bytes, and so on until you
reach the end, then it would indeed be VERY weird if there were parts
of the file that weren't in the returned (byte) strings. But if you
ask for a line, and then another line, and another line, then it's
quite reasonable to interpret U+000A as "line separation" rather than
"line termination", and not return it. (Both interpretations make
sense. I just wish the most obvious form of iteration gave the
cleaner/tidier version, or at very least that there be some really
obvious way to ask for lines-without-endings.) Imagine the output of
GNU find as a series of records. You can ask for those to be separated
by newlines (the default, or -print), or by NULs (with the -print0
command). In either case, the records do not *contain* that value,
they're separated by it; the records consist of file names.

ChrisA


From rustompmody at gmail.com  Sat Mar 22 13:16:43 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Sat, 22 Mar 2014 10:16:43 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8388.1395479446.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8388.1395479446.18130.python-list@python.org>
Message-ID: <891df3fe-2cd8-4615-9f9c-0e6f62af764a@googlegroups.com>

On Saturday, March 22, 2014 2:39:56 PM UTC+5:30, Ian wrote:
> On Fri, Mar 21, 2014 at 8:06 PM, Rustom Mody  wrote:
> > Two: A comprehension variable is not bound but reassigned across the
> > comprehension. This problem remains in python3 and causes weird behavior when
> > lambdas are put in a comprehension

> Because Python as a language only has the concept of assignment, not
> binding.  I think it would be weird and confusing if variables worked
> this way in comprehensions and nowhere else.

Bizarre viewpoint!

When you do this:

> There is also the default argument trick:

> >>> fl = [lambda y, *, x=x: x+y for x in [1,2,3]]
> >>> [f(2) for f in fl]
> [3, 4, 5]

how is that not-a-binding solution?

More generally, insofar as variable-scopes can be made and exited, there
is binding.  Its just that imperative languages have
- assignment wherein the shape of the environment is preserved but 
its content is changed 
- there are binding-constructs -- functions, methods, classes etc etc
-- which leave extant bindings intact but create/remove new ones.

Ok, functional languages have only the latter.
But only the former?? Beyond assembly language I dont know what 
that would/could be...


From rustompmody at gmail.com  Sat Mar 22 13:29:47 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Sat, 22 Mar 2014 10:29:47 -0700 (PDT)
Subject: Python - Caeser Cipher Not Giving Right Output
In-Reply-To: <mailman.8400.1395498157.18130.python-list@python.org>
References: <7eee0f2b-0d5f-409e-ae4e-8c9c1af31d74@googlegroups.com>
 <mailman.8341.1395371543.18130.python-list@python.org>
 <bda05813-d186-41ea-a40d-5d36f90a8fed@googlegroups.com>
 <lggdbi$ku6$1@ger.gmane.org>
 <mailman.8400.1395498157.18130.python-list@python.org>
Message-ID: <3ddffa42-6f51-4950-94bd-560b9c9547b1@googlegroups.com>

On Saturday, March 22, 2014 7:52:28 PM UTC+5:30, Ian wrote:
> On Mar 20, 2014 9:59 PM, "Dave Angel" <da... at davea.name> wrote:
> > ?dtra... at gmail.com Wrote in message:
> > > And I was wondering how I would add the partenthesis because I tried:
> > > return numtochar(c1 + c2 (%26)) and it gave me an error.
> > Please help us to help you by actually showing the traceback.
> > ?Doesn't matter in this case, but...
> > What order do you want the add and the modulo to happen? ?Use the
> > ?parentheses to say so.
> Ah, but he did. x = y + z (mod m) is a perfectly well-formed math equation. Not the OP's fault if it doesn't work that way in Python.

!!!!!
!I forgot that parse!


From albert at spenarnc.xs4all.nl  Sat Mar 22 13:32:05 2014
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 22 Mar 2014 17:32:05 GMT
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org> <bortetF7t42U1@mid.individual.net>
 <lgasdj$93f$1@ger.gmane.org>
 <mailman.8270.1395195147.18130.python-list@python.org>
Message-ID: <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>

In article <mailman.8270.1395195147.18130.python-list at python.org>,
Tim Chase  <python.list at tim.thechases.com> wrote:
>On 2014-03-18 21:38, Terry Reedy wrote:
>> At least with hg, one should best test the code in the working
>> directory *before* committing to the local repository.
>
>I don't know if this is a hg-vs-git way of thinking, but I tend to
>frequently commit things on a private development branch regardless
>of brokenness, but once I get it working, I flatten & clean up those
>changes ("rebase" in git terms, which I believe has been adopted as a
>standardly-available-but-not-enabled-by-default module in hg) into
>logical units of change-sets that I then test individually before
>applying them to my more public-facing branch.  This produces clean
>history that makes it easy for others to see what's going on.

I see it this way that all code is broken to at least a small
extent, so it is stupid to not to save into source control because
code is not yet flawless.
I use RCS (!) for my eulerproject.net programs, and
I save every small milestone. There is just one important rule,
if you save code that has (severe) restrictions, keep
track of it in the submission message, otherwise you loose your
bearings.
Basically the first ten of so versions (before the tag WINNER)
just don't solve the problem.
(Of course euler problems are hard, three rewrites are not
uncommon.)

I compare the in between versions with the nails they put in
the mountainside in climbing. It is a point below which you'll
never need to slide back.

>
>-tkc

Groetjes Albert
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From breamoreboy at yahoo.co.uk  Sat Mar 22 13:57:21 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 22 Mar 2014 17:57:21 +0000
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <CALwzid=i-NbZPmAq9suMwvgGCPvu_9=sxgPVf=Mk9aBGXRRtfg@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <CALwzid=i-NbZPmAq9suMwvgGCPvu_9=sxgPVf=Mk9aBGXRRtfg@mail.gmail.com>
Message-ID: <lgkitp$vc9$1@ger.gmane.org>

On 22/03/2014 09:09, Ian Kelly wrote:
> On Fri, Mar 21, 2014 at 8:06 PM, Rustom Mody <rustompmody at gmail.com> wrote:
>> Two: A comprehension variable is not bound but reassigned across the
>> comprehension. This problem remains in python3 and causes weird behavior when
>> lambdas are put in a comprehension
>
> Because Python as a language only has the concept of assignment, not
> binding.  I think it would be weird and confusing if variables worked
> this way in comprehensions and nowhere else.
>

My understanding has always been that an expression of the rhs is bound 
to a name of the lhs.  So is my understanding wrong, or is the above 
wrong, or are we talking at cross purposes, or what?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From albert at spenarnc.xs4all.nl  Sat Mar 22 13:53:25 2014
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 22 Mar 2014 17:53:25 GMT
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org> <lge2v9$h0l$1@ger.gmane.org>
 <mailman.8290.1395299735.18130.python-list@python.org>
 <bp17s6Fbs18U1@mid.individual.net>
Message-ID: <532dce15$0$24918$e4fe514c@dreader36.news.xs4all.nl>

In article <bp17s6Fbs18U1 at mid.individual.net>,
Gregory Ewing  <greg.ewing at canterbury.ac.nz> wrote:
>Chris Angelico wrote:
>> You can then offer a non-source-control means of downloading that
>> specific revision.
>
>Just keep in mind the downside that you can't then
>push or pull your changes directly back into the main
>repository. You can generate a patch file for the
>project maintainer to apply, however. Hg makes it
>very easy to produce a patch file between any two
>revisions.
>
>Also, unless the project is truly ancient, the
>whole history might not be as big as you expect.
>The code presumably grew to its present size
>incrementally, in an approximately monotonic
>manner, so the sum of all the diffs is probably
>about the same order of magnitude as the current
>code size.
>
>As an experiment, I just cloned a copy of the
>CPython repository, and it's about 300MB. A
>tarball of Python 3.2 that I downloaded and
>compiled earlier is about 75MB. That's a ratio
>of about 4, and CPython is a pretty ancient
>project!

This post made me worry for the first time about one project of
mine (ciforth). It started in 2000 with an msdos assembler file,
and after several hundreds version it has accumulated doc's and test's
and is now usable on linux, windows whatnot.

Since 2000 the cvs style archive has grown to 2 megabyte,
for a current version of 400 kbyte. I kept the smallest of changes,
and at times was very happy I did.

Bottom line, the grow of a source archive cannot keep up
with LAN and Internet speeds and hard disk sizes.

>
>--
>Greg

Groetjes Albert
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From laurent.pointal at free.fr  Sat Mar 22 14:28:35 2014
From: laurent.pointal at free.fr (Laurent Pointal)
Date: Sat, 22 Mar 2014 19:28:35 +0100
Subject: Controlling buffer alignment in file.read()
References: <mailman.8260.1395174272.18130.python-list@python.org>
 <bos1vgF8r6oU1@mid.individual.net>
 <mailman.8265.1395184430.18130.python-list@python.org>
Message-ID: <532dd653$0$2370$426a74cc@news.free.fr>

Haralanov, Mitko wrote:

>> For control at that level you'd be better off using
>> direct system calls, i.e. os.open() and os.read(),
>> then you can read exacty the number of bytes you want.
>> 
> 
> The problem is not controlling the number of bytes read. That part seems
> to be working. The issue is that the buffer into which the data is placed
> needs to be of certain alignment (8byte-aligned). Python does not seem to
> have a way that allows me to control that.
> 
> Thanks,
> - Mitko

Did you try to set buffering parameter to 0 (unbuffered) ?

Eventually going to os.open() which map tp low level (eventually followed by 
an os.fdopen())

http://docs.python.org/2/library/os.html#os.open

A+
Laurent.



From marko at pacujo.net  Sat Mar 22 14:40:44 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 22 Mar 2014 20:40:44 +0200
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <CALwzid=i-NbZPmAq9suMwvgGCPvu_9=sxgPVf=Mk9aBGXRRtfg@mail.gmail.com>
 <mailman.8404.1395511066.18130.python-list@python.org>
Message-ID: <87mwgi3wlv.fsf@elektro.pacujo.net>

Mark Lawrence <breamoreboy at yahoo.co.uk>:

> On 22/03/2014 09:09, Ian Kelly wrote:
>> Because Python as a language only has the concept of assignment, not
>> binding. I think it would be weird and confusing if variables worked
>> this way in comprehensions and nowhere else.
>
> My understanding has always been that an expression of the rhs is
> bound to a name of the lhs. So is my understanding wrong, or is the
> above wrong, or are we talking at cross purposes, or what?

Hard to say without knowing more of your understanding.

Even Scheme doesn't have purely classical variable binding because
variables can be assigned to. You will notice that right away when you
try to implement a lisp dialect; a purely binding (substituting)
implementation fails with set!/setq because there is no variable to
assign a value to.

Python variables are named memory slots you can peek and poke into. Not
so in a purely functional language where variables are physically
removed from the code before the code is executed.

Example:

    def redouble(x):
        return x + x

    redouble(17 + 4)

If Python were simply binding variables in the purely functional sense,
the interpreter would first evaluate 17 + 4 and then make a copy of the
"redouble" function substituting the result (21) for each syntactic
occurrence of x:

    def __redouble__234001942():
        return 21 + 21

The interpreter would then proceed to evaluate the variable-less
function instance.

If you leave out assignment, there is really no difference between the
two models. Only if you don't have assignment, you don't need to
complicate your computational model with memory. Instead, you deal with
things like continuations.

In fact, even "def" violates the classic functional paradigm. For
example, to calculate 10's factorial without assignments, you can do
this (even in Python):

   (lambda n: (lambda fac: fac(fac, n)) \
      (lambda fac, n: 1 if n < 2 else n * fac(fac, n - 1)))(10)


Marko


From rustompmody at gmail.com  Sat Mar 22 14:42:42 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Sat, 22 Mar 2014 11:42:42 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8404.1395511066.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <CALwzid=i-NbZPmAq9suMwvgGCPvu_9=sxgPVf=Mk9aBGXRRtfg@mail.gmail.com>
 <mailman.8404.1395511066.18130.python-list@python.org>
Message-ID: <6fa40395-e8db-4597-ab8e-546132595586@googlegroups.com>

The foll is fairly standard fare in denotational semantics -- please excuse
the length!

In order to understand (formally) the concept of 'variable'
we need to have at the least a concept of name(or identifier) -> value mapping.
This mapping is called an 'environment'

If we stop at that we get the 'simplest' (at least from a mathematical
pov!!) language -- ? calculus.

However programming languages also need to be implemented -- typically
on von Neumann machines. So we make 'Variable' a composition of two functions:
Env   : Identifier -> Location
Store : Location -> Value

This seems fine and dandy until we realize that if the compositon is of
non one-one onto functions all kinds of troubles result; eg
-- Two locations going to one value -- aliasing
-- Store partial at a location -- uninitialized variable
etc etc the most innocuous looking?
-- assignment becomes a higher order function
because it converts a starting id -> -> value mapping to a new mapping


Seeing all these difficulties, some religious zealots (aka functional
programmers) decide that this composite mapping is the root of the problem
-- throw it out -- no aliasing, no assignment, no time. [Minor problem --
How to implement -- remains!]

The non-religious bigots (also called C programmers) see that managing
the Env at one time and the Store at a later time (the two times
are usually called compile-time and run-time but like bell-bottoms these
words are currently unfashionable!) can produce very effective engineering
expedience.

So strictly speaking whenever we have variables we have binding
[Probably mathematica is an exception... dunno for sure]

More loosely and conventionally if the mapping is a single direct one:
Env: Variable -> Value
as in ? calculus, functional languages etc, they are called binding-languages

To distinguish, the 'other' languages which need a 
compose of Environment and Store are called variously:

- imperative language
- reference semantics
- conventional (imperative) variable (vs mathematical variable)
etc

IOW in most (normal) languages we have constructs to change the shape
of the environment and we have constructs to change the content of the
environment. The single pre-eminent way for the latter is assignment,
function is the typical way for the former.

[Unfortunately this is not universally true:
In C we have initialized variables that look like assignment but is not.
In python the exception is what Ian calls the default variable trick:
x=x would be a rather asinine assignment. But its not an assignment at all,
it just looks like one]

So no...

> My understanding has always been that an expression of the rhs is bound 
> to a name of the lhs.  So is my understanding wrong, or is the above 
> wrong, or are we talking at cross purposes, or what?

assignment changes the content of the env, functions change the shape
-- which latter you may call binding.


From python.list at tim.thechases.com  Sat Mar 22 14:49:17 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Sat, 22 Mar 2014 13:49:17 -0500
Subject: Question about Source Control
In-Reply-To: <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>
References: <lg6s09$irl$1@ger.gmane.org> <bortetF7t42U1@mid.individual.net>
 <lgasdj$93f$1@ger.gmane.org>
 <mailman.8270.1395195147.18130.python-list@python.org>
 <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>
Message-ID: <20140322134917.080bada6@bigbox.christie.dr>

On 2014-03-22 17:32, Albert van der Horst wrote:
> >I don't know if this is a hg-vs-git way of thinking, but I tend to
> >frequently commit things on a private development branch regardless
> >of brokenness, but once I get it working, I flatten & clean up
> >those changes ("rebase" in git terms, which I believe has been
> >adopted as a standardly-available-but-not-enabled-by-default
> >module in hg) into logical units of change-sets that I then test
> >individually before applying them to my more public-facing
> >branch.  This produces clean history that makes it easy for others
> >to see what's going on.  
> 
> I see it this way that all code is broken to at least a small
> extent, so it is stupid to not to save into source control because
> code is not yet flawless.

I agree that skipping the commits just because it might be broken is
a foolish idea.  However, with most VCS tools, your commits can look
something like

  Baseline -> A -> B -> C -> D -> E -> F -> G {head/tip}

but A, C, & E all comprise one conceptual change, while B & G are
another, and D & F cancel each other out.  You can either cherry-pick
those changes or rebase (with git or the hg plugin) so that the
history looks like

  Baseline -> (ACE) -> (BG) {head/tip}

With git, the history isn't actually discarded immediately, but
rather just gets a parallel version (which may or may not have a
reference to it; if it doesn't it will get cleaned up about a month
later according to your garbage-collection settings) so your repo
ends up looking something like

  Baseline -> A -> B -> C -> D -> E -> F -> G {orphaned or named}
        \---> (ACE) -> (BG) {head/tip}

You can then publish that conceptually clean (and hopefully
tested&working) branch while simultaneously having the full history
in the event you need it.  That said, I almost never want the
intermediate work product once I have a final clean version, so I
just let git GC that for me.

-tkc















From fomcl at yahoo.com  Sat Mar 22 16:01:22 2014
From: fomcl at yahoo.com (Albert-Jan Roskam)
Date: Sat, 22 Mar 2014 13:01:22 -0700 (PDT)
Subject: Question about Source Control
In-Reply-To: <20140322134917.080bada6@bigbox.christie.dr>
References: <lg6s09$irl$1@ger.gmane.org> <bortetF7t42U1@mid.individual.net>
 <lgasdj$93f$1@ger.gmane.org>
 <mailman.8270.1395195147.18130.python-list@python.org>
 <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>
 <20140322134917.080bada6@bigbox.christie.dr>
Message-ID: <1395518482.78665.YahooMailNeo@web163804.mail.gq1.yahoo.com>

Hi,

I can recommend the book "Pragmatic Guide to Git". Very practical and to the point:

http://www.amazon.com/Pragmatic-Guide-Git-Programmers/dp/1934356727/ref=sr_1_1/184-0142481-0484062?ie=UTF8&qid=1395518159&sr=8-1&keywords=pragmatic+guide+to+git


I addition, I read a big fat super-exhaustive book, I believe it' s this one (there are two Git books with a bat!):

http://www.amazon.com/Version-Control-Git-collaborative-development/dp/1449316387/ref=sr_1_2/184-0142481-0484062?ie=UTF8&qid=1395518159&sr=8-2&keywords=pragmatic+guide+to+git


The former is for common tasks that are not common enough to remember right away. The latter is for reference.

I only have experience with git and subversion. I like git much better. But any SCM is better than none at all.

?
Regards,

Albert-Jan




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a 

fresh water system, and public health, what have the Romans ever done for us?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 





On Saturday, March 22, 2014 7:49 PM, Tim Chase <python.list at tim.thechases.com> wrote:
 
On 2014-03-22 17:32, Albert van der Horst wrote:
>> >I don't know if this is a hg-vs-git way of thinking, but I tend to
>> >frequently commit things on a private development branch regardless
>> >of brokenness, but once I get it working, I flatten & clean up
>> >those changes ("rebase" in git terms, which I believe has been
>> >adopted as a standardly-available-but-not-enabled-by-default
>> >module in hg) into logical units of change-sets that I then test
>> >individually before applying them to my more public-facing
>> >branch.? This produces clean history that makes it easy for others
>> >to see what's going on.? 
>> 
>> I see it this way that all code is broken to at least a small
>> extent, so it is stupid to not to save into source control because
>> code is not yet flawless.
>
>I agree that skipping the commits just because it might be broken is
>a foolish idea.? However, with most VCS tools, your commits can look
>something like
>
>? Baseline -> A -> B -> C -> D -> E -> F -> G {head/tip}
>
>but A, C, & E all comprise one conceptual change, while B & G are
>another, and D & F cancel each other out.? You can either cherry-pick
>those changes or rebase (with git or the hg plugin) so that the
>history looks like
>
>? Baseline -> (ACE) -> (BG) {head/tip}
>
>With git, the history isn't actually discarded immediately, but
>rather just gets a parallel version (which may or may not have a
>reference to it; if it doesn't it will get cleaned up about a month
>later according to your garbage-collection settings) so your repo
>ends up looking something like
>
>? Baseline -> A -> B -> C -> D -> E -> F -> G {orphaned or named}
>? ? ? ? \---> (ACE) -> (BG) {head/tip}
>
>You can then publish that conceptually clean (and hopefully
>tested&working) branch while simultaneously having the full history
>in the event you need it.? That said, I almost never want the
>intermediate work product once I have a final clean version, so I
>just let git GC that for me.
>
>
>-tkc
>
>
>
>
>
>
>
>
>
>
>
>
>
>-- 
>https://mail.python.org/mailman/listinfo/python-list
>
>
>
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From tjreedy at udel.edu  Sat Mar 22 16:13:59 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sat, 22 Mar 2014 16:13:59 -0400
Subject: newbie - Does IDLE care about sitecustomize.py?
In-Reply-To: <f10f31d6-a28a-4327-9468-d2c1727b474c@googlegroups.com>
References: <1132151829.600244.9210@g14g2000cwa.googlegroups.com>
 <f10f31d6-a28a-4327-9468-d2c1727b474c@googlegroups.com>
Message-ID: <lgkqu1$fh7$1@ger.gmane.org>

On 3/22/2014 9:41 AM, vikram.denizen at gmail.com wrote:
> Could you figure this out?
>
> On Wednesday, November 16, 2005 10:37:09 PM UTC+8, bobu... at yahoo.com wrote:
>> I have the following test script in the file customize.py
>>
>> # C:\Python24\Lib\site-packages\sitecustomize.py
>> print "test text from sitecustomize"
>>
>> If start Python from command prompt I get
>>
>> C:\Python24>python
>> test in sitecustomize
>> Python 2.4.1 (#65, Mar 30 2005, 09:13:57) [MSC v.1310 32 bit (Intel)]
>> on win32

Note: running on Windows

>> Type "help", "copyright", "credits" or "license" for more information.
>>
>> which shows that sitecustomize.py works
>>
>>
>> Now if I start IDLE I only get
>>
>> IDLE 1.1.1

On Windows, the default mode of running Idle is without a console 
window, with pythonw.exe. Site.py and sitecustomize.py are run before 
anything else and any output is discarded. I propose to note this where 
sitecustomize.py is explained.

http://bugs.python.org/issue21026

-- 
Terry Jan Reedy



From tjreedy at udel.edu  Sat Mar 22 16:48:02 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sat, 22 Mar 2014 16:48:02 -0400
Subject: terminate a program gracefully from a thread
In-Reply-To: <CAOuJsMny-DV2kLS2EU1=FtHr6zkMH__-Q-2z8_-wnaSKmap8iA@mail.gmail.com>
References: <CAOuJsMny-DV2kLS2EU1=FtHr6zkMH__-Q-2z8_-wnaSKmap8iA@mail.gmail.com>
Message-ID: <lgksts$m2v$1@ger.gmane.org>

On 3/22/2014 8:40 AM, Jabba Laci wrote:

> I have a script (see below) that I want to terminate after X seconds.
> The main loop of the program is waiting for user input.
> The program enters the main loop and I try to shut down the program
> after X seconds from a thread but I can't figure out how to do it. The
> program should also do some cleanup before termination, so the shut
> down must be graceful.

Although you have gotten comments specific to your problem, this type of 
thing should be easy (in just one thread) with asyncio (new in 3.4, 
backport on PyPI).

-- 
Terry Jan Reedy



From simonhf at gmail.com  Sat Mar 22 16:45:07 2014
From: simonhf at gmail.com (Simon Hardy-Francis)
Date: Sat, 22 Mar 2014 13:45:07 -0700 (PDT)
Subject: Help needed to create a Python extension library for an existing
 shared memory hash table library
Message-ID: <ba423f7b-dd9a-49d0-a37a-9fe51541fe16@googlegroups.com>

Hi Python fans, I just released my first open source project ever called SharedHashFile [1]. It's a shared memory hash table written in C. Some guy on Quora asked [2] whether there's an extension library for Python coming out. I would like to do one but I know little about Python. I was wondering if anybody in this group has experience writing extension libraries for Python? Could you help? Or could we collaborate? Thanks and all the best, Simon

[1] https://github.com/simonhf/sharedhashfile
[2] http://www.quora.com/Inter-Process-Communication-1/Whats-a-good-library-to-share-a-key-value-store-across-multiple-processes-through-shared-memory


From vasudevram at gmail.com  Sat Mar 22 16:59:46 2014
From: vasudevram at gmail.com (vasudevram)
Date: Sat, 22 Mar 2014 13:59:46 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
Message-ID: <8aa0b833-e7b7-485b-8258-c59eebdace93@googlegroups.com>


Thanks to all those who answered.

- Vasudev


From super.thrinaxodon at dumbass.bitch.invalid  Sat Mar 22 17:20:59 2014
From: super.thrinaxodon at dumbass.bitch.invalid (SUPER THRINAXODON DUMBASS)
Date: Sat, 22 Mar 2014 17:20:59 -0400
Subject: RICHARD LEAKEY RECENTLY ARRESTED -- THE THRINAXODON TIMES REPORTS
 YOU CRAP, YOU CALL OUT BULLSHIT!
Message-ID: <lgkurd$n33$2@speranza.aioe.org>

====================
 >LOOK, MOM! A BIRD, A PLANE, A THRINAXODON!
====================
 >
RICHARD LEAKEY WAS RECENTLY ARRESTED IN CONNECTION TO EVOLUTIONARY SCANDALS.
 >
THRINAXODON CAUGHT THE WHOLE SCENE!
 >
ONLY ONE GUESS TO WHAT RICHARD LEAKEY WAS UP TO WILL SHUT YOUR MOUTHS!
 >
RICHARD LEAKEY WAS BRAINWASHING CHILDREN INTO THE SCAM OF HUMAN 
EVOLUTION JUST TO MAKE BIG BUCKS...
 >
==================================
EVIDENCE THAT HUMANS LIVED IN THE DEVONIAN:

https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/6f501c469c7af24f# 


https://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/3aad75c16afb0b82# 


-- 
---Thrinaxodon



From rhodri at wildebst.org.uk  Sat Mar 22 20:32:22 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Sun, 23 Mar 2014 00:32:22 -0000
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
 <9edb4ea0-5faf-4369-8021-48afa9800a34@googlegroups.com>
Message-ID: <op.xc5fr8pn5079vu@gnudebeest>

On Sat, 22 Mar 2014 05:26:26 -0000, Rustom Mody <rustompmody at gmail.com>  
wrote:

> Well almost...
> Except that the 'loop' I am talking of is one of
> def loop():
>      return [yield (lambda: x) for x in [1,2,3]]
> or
>      return (yield (lambda: x) for x in [1,2,3])
> or just plain ol
>      (lambda x:  for x in [1,2,3])
> IOW loop is an imperative construct, comprehensions are declarative

I'm sorry, you've made a logical leap too far here.  I understand loops  
being imperative, but how are comprehensions declarative?  What do they  
declare that the loop equivalent doesn't.

You've made a great deal of the "for" in a comprehension not having the  
same meaning as the "for" in a loop.  That may well be true in the  
equivalent Haskell constructs (I don't speak or write Haskell), but I  
think you are wrong in Python.  If so, please stop trying to write Haskell  
in Python; you'll be as happy as the friend of mine I've finally persuaded  
to stop writing Fortran in Python, I promise!

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From steve+comp.lang.python at pearwood.info  Sat Mar 22 21:07:32 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 23 Mar 2014 01:07:32 GMT
Subject: Python MSI not installing, log file showing name of a
 Viatnemese communist revolutionary
References: <a5ea51ec-9d99-4119-9ee7-2b4b3cbecb69@googlegroups.com>
 <mailman.8372.1395441071.18130.python-list@python.org>
 <827c7585-6c2a-4329-861f-0fdaa629b050@googlegroups.com>
 <f335d76d-2746-40f3-931a-3d46dd469bc1@googlegroups.com>
 <mailman.8374.1395441860.18130.python-list@python.org>
 <lgj1pd$10g$1@speranza.aioe.org>
 <532da347$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8402.1395500969.18130.python-list@python.org>
Message-ID: <532e33d4$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sun, 23 Mar 2014 02:09:20 +1100, Chris Angelico wrote:

> On Sun, Mar 23, 2014 at 1:50 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> Line endings are terminators: they end the line. Whether you consider
>> the terminator part of the line or not is a matter of opinion (is the
>> cover of a book part of the book?) but consider this:
>>
>>     If you say that the end of lines are *not* part of the line, then
>>     that implies that some parts of the file are not inside any line at
>>     all. And that would be just weird.
> 
> Not so weird IMO. A file is not a concatenation of lines; it is a stream
> of bytes. 

But a *text file* is a concatenation of lines. The "text file" model is 
important enough that nearly all programming languages offer a line-based 
interface to files, and some (Python at least, possibly others) make it 
the default interface so that iterating over the file gives you lines 
rather than bytes -- even in "binary" mode.


> Now, if you ask Python to read you 512 bytes from a binary
> file, and then ask for another 512 bytes, and so on until you reach the
> end, then it would indeed be VERY weird if there were parts of the file
> that weren't in the returned (byte) strings. But if you ask for a line,
> and then another line, and another line, then it's quite reasonable to
> interpret U+000A as "line separation" rather than "line termination",
> and not return it. (Both interpretations make sense. I just wish the
> most obvious form of iteration gave the cleaner/tidier version, or at
> very least that there be some really obvious way to ask for
> lines-without-endings.)

There is: call strip('\n') on the line after reading it. Perl and Ruby 
spell it chomp(). Other languages may spell it differently. I don't know 
of any language that automatically strips newlines, probably because you 
can easily strip the newline from the line, but if the language did it 
for you, you cannot reliably reverse it.


> Imagine the output of GNU find as a series of
> records. You can ask for those to be separated by newlines (the default,
> or -print), or by NULs (with the -print0 command). In either case, the
> records do not *contain* that value, they're separated by it; the
> records consist of file names.

I have no problem with that: when interpreting text as a record with 
delimiters, e.g. from a CSV file, you normally exclude the delimiter. 
Sometimes the line terminator does double-duty as a record delimiter as 
well.

Reading from a file is considered a low-level operation. Reading 
individual bytes in binary mode is the lowest level; reading lines in 
text mode is the next level, built on top of the lower binary mode. You 
build higher protocols on top of one or the other of that mode, e.g. 
"read a zip file" would be built on top of binary mode, "read a csv file" 
would be built on top of text mode.

As a low-level protocol, you ought to be able to copy a file without 
changing it by reading it in then writing it out:

for blob in infile:
    outfile.write(blob)


ought to work whether you are in text mode or binary mode, so long as the 
infile and outfile are opened in the same mode. If Python were to strip 
newlines, that would no longer be the case.

(Even high-level protocols should avoid unnecessary modifications to 
files. One of the more annoying, if not crippling, limitations to the 
configparser module is that reading an INI file in, then writing it out 
again destroys the high-level structure of the file: comments and blank 
lines are stripped, and records may be re-ordered.)



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Sat Mar 22 21:37:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 23 Mar 2014 12:37:43 +1100
Subject: Reading in cooked mode (was Re: Python MSI not installing, log file
 showing name of a Viatnemese communist revolutionary)
Message-ID: <CAPTjJmq-DkLxwAva_pyZ2YB7H4qV5RnzsXAJQDfPVdYhT8ffOw@mail.gmail.com>

On Sun, Mar 23, 2014 at 12:07 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Sun, 23 Mar 2014 02:09:20 +1100, Chris Angelico wrote:
>
>> On Sun, Mar 23, 2014 at 1:50 AM, Steven D'Aprano
>> <steve+comp.lang.python at pearwood.info> wrote:
>>> Line endings are terminators: they end the line. Whether you consider
>>> the terminator part of the line or not is a matter of opinion (is the
>>> cover of a book part of the book?) but consider this:
>>>
>>>     If you say that the end of lines are *not* part of the line, then
>>>     that implies that some parts of the file are not inside any line at
>>>     all. And that would be just weird.
>>
>> Not so weird IMO. A file is not a concatenation of lines; it is a stream
>> of bytes.
>
> But a *text file* is a concatenation of lines. The "text file" model is
> important enough that nearly all programming languages offer a line-based
> interface to files, and some (Python at least, possibly others) make it
> the default interface so that iterating over the file gives you lines
> rather than bytes -- even in "binary" mode.

And lines are delimited entities. A text file is a sequence of lines,
separated by certain characters.

>> (Both interpretations make sense. I just wish the
>> most obvious form of iteration gave the cleaner/tidier version, or at
>> very least that there be some really obvious way to ask for
>> lines-without-endings.)
>
> There is: call strip('\n') on the line after reading it. Perl and Ruby
> spell it chomp(). Other languages may spell it differently. I don't know
> of any language that automatically strips newlines, probably because you
> can easily strip the newline from the line, but if the language did it
> for you, you cannot reliably reverse it.

That's not a tidy way to iterate, that's a way to iterate and then do
stuff. Compare:

for line in f:
    # process line with newline

for line in f:
    line = line.strip("\n")
    # process line without newline, as long as it doesn't have \r\n or something

for line in f:
    line = line.split("$")
    # process line as a series of dollar-delimited fields

The second one is more like the third than the first. Python does not
offer a tidy way to do the common thing, which is reading the content
of the line without its terminator.

>> Imagine the output of GNU find as a series of
>> records. You can ask for those to be separated by newlines (the default,
>> or -print), or by NULs (with the -print0 command). In either case, the
>> records do not *contain* that value, they're separated by it; the
>> records consist of file names.
>
> I have no problem with that: when interpreting text as a record with
> delimiters, e.g. from a CSV file, you normally exclude the delimiter.
> Sometimes the line terminator does double-duty as a record delimiter as
> well.

So why is the delimiter excluded when you treat the file as CSV, but
included when you treat the file as lines of text?

> Reading from a file is considered a low-level operation. Reading
> individual bytes in binary mode is the lowest level; reading lines in
> text mode is the next level, built on top of the lower binary mode. You
> build higher protocols on top of one or the other of that mode, e.g.
> "read a zip file" would be built on top of binary mode, "read a csv file"
> would be built on top of text mode.

I agree that reading a binary file is the lowest level. Reading a text
file is higher level, but to me "reading a text file" means "reading a
binary file and decoding it into Unicode text", and not "... and
dividing it into lines". Bear in mind that reading a CSV file can be
built on top of a Unicode decode, but not on a line-based iteration
(in case there are newlines inside quotes).

> As a low-level protocol, you ought to be able to copy a file without
> changing it by reading it in then writing it out:
>
> for blob in infile:
>     outfile.write(blob)
>
>
> ought to work whether you are in text mode or binary mode, so long as the
> infile and outfile are opened in the same mode. If Python were to strip
> newlines, that would no longer be the case.

All you need is a "writeln" method that re-adds the newline, and then
it's correctly round-tripping, based on what you've already stated
about the file: that it's a series of lines of text. It might not be a
byte-equivalent round-trip if you're changing newline style, any more
than it already won't be for other reasons (file encoding, for
instance). By reading the file as a series of Unicode lines, you're
declaring that it contains lines of Unicode text, not arbitrary bytes,
and so a valid representation of those lines of Unicode text is a
faithful reproduction of the file. If you want a byte-for-byte
identical file, open it in binary mode to do the copy; that's what we
learn from FTPing files between Linux and Windows.

> (Even high-level protocols should avoid unnecessary modifications to
> files. One of the more annoying, if not crippling, limitations to the
> configparser module is that reading an INI file in, then writing it out
> again destroys the high-level structure of the file: comments and blank
> lines are stripped, and records may be re-ordered.)

Precisely. If you read it as an INI file and then rewrite it as an INI
file, you risk damaging that sort of thing. If you parse a file as a
Python script, and then reconstitute it from the AST (with one of the
unparsers available), you have a guarantee that the result will
execute the exact same code. But it won't be the same file (although
Python's AST does guarantee order, unlike your INI file example).
Actually, this might be a useful transformation to do, sometimes -
part of a diff suite, maybe - if the old and new versions are
identical after an AST parse/unparse transformation, you don't need to
re-run tests, because there's no way a code bug can have been
introduced.

ChrisA


From davea at davea.name  Sat Mar 22 22:18:55 2014
From: davea at davea.name (Dave Angel)
Date: Sat, 22 Mar 2014 22:18:55 -0400 (EDT)
Subject: Question about Source Control
References: <lg6s09$irl$1@ger.gmane.org> <bortetF7t42U1@mid.individual.net>
 <lgasdj$93f$1@ger.gmane.org>
 <mailman.8270.1395195147.18130.python-list@python.org>
 <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>
 <20140322134917.080bada6@bigbox.christie.dr>
 <1395518482.78665.YahooMailNeo@web163804.mail.gq1.yahoo.com>
Message-ID: <lglg0u$446$1@ger.gmane.org>

 Albert-Jan Roskam <fomcl at yahoo.com> Wrote in message:
> 

In addition to posting in html format,  you have also set the font
 size too small for me to easily read. Reason number 12 for
 posting in text mode in a text newsgroup. 

-- 
DaveA



From cs at zip.com.au  Sat Mar 22 22:16:35 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Sun, 23 Mar 2014 13:16:35 +1100
Subject: Reading in cooked mode (was Re: Python MSI not installing, log
 file showing name of a Viatnemese communist revolutionary)
In-Reply-To: <CAPTjJmq-DkLxwAva_pyZ2YB7H4qV5RnzsXAJQDfPVdYhT8ffOw@mail.gmail.com>
References: <CAPTjJmq-DkLxwAva_pyZ2YB7H4qV5RnzsXAJQDfPVdYhT8ffOw@mail.gmail.com>
Message-ID: <20140323021635.GA90771@cskk.homeip.net>

On 23Mar2014 12:37, Chris Angelico <rosuav at gmail.com> wrote:
> On Sun, Mar 23, 2014 at 12:07 PM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
> > On Sun, 23 Mar 2014 02:09:20 +1100, Chris Angelico wrote:
> >> On Sun, Mar 23, 2014 at 1:50 AM, Steven D'Aprano
> >> <steve+comp.lang.python at pearwood.info> wrote:
> >>> Line endings are terminators: they end the line. Whether you consider
> >>> the terminator part of the line or not is a matter of opinion (is the
> >>> cover of a book part of the book?) but consider this:
> >>>
> >>>     If you say that the end of lines are *not* part of the line, then
> >>>     that implies that some parts of the file are not inside any line at
> >>>     all. And that would be just weird.
> >>
> >> Not so weird IMO. A file is not a concatenation of lines; it is a stream
> >> of bytes.
> >
> > But a *text file* is a concatenation of lines. The "text file" model is
> > important enough that nearly all programming languages offer a line-based
> > interface to files, and some (Python at least, possibly others) make it
> > the default interface so that iterating over the file gives you lines
> > rather than bytes -- even in "binary" mode.
> 
> And lines are delimited entities. A text file is a sequence of lines,
> separated by certain characters.
[...snip...]

As far as I'm concerned, a text file is a sequence lines, each of
which is _terminated_ by a newline (or the OS end-of-line flavour).

So I say "terminated by", not "separated by".

Plenty of people use editors that consider end-of-line to be a
separator and not a terminator, leading to supposed text files
lacking trailing newlines (or end-of-line of OS).

I consider this sloppy and error prone.

I like to be able to read a file and if it lacks a final newline
then I have a good clue that the file was incompletely written.
Editors (and other tools) that won't enforce a trailing newline as
omitting an easy way to give a fairly robust indication of completion
at no benefit to the user. (Not to mention the visual annoyance of
"cat file" when there's no trailing newline.)

So I'm happy to write code that errors if a line lacks a trailing
newline, and thus I consider the newline to be an intergral part
of the line.

Having passed that sanity check, for most machine readable text
formats I'm usually happy to use:

  line = line.rstrip()

to get the salient part of the line.

(Of course, lines extended with slosh-extension or the like need
pickier handling.)

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

If at first you don't succeed, your sky-diving days are over.
        - Paul Blumstein, paulb at harley.tti.com, DoD #36


From ian.g.kelly at gmail.com  Sat Mar 22 22:46:28 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 22 Mar 2014 20:46:28 -0600
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <op.xc5fr8pn5079vu@gnudebeest>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
 <9edb4ea0-5faf-4369-8021-48afa9800a34@googlegroups.com>
 <op.xc5fr8pn5079vu@gnudebeest>
Message-ID: <CALwzidm7mp_8EhwLfJs=FX-JVVRUhq9c_-H07R2h-gz_W5f+Wg@mail.gmail.com>

On Sat, Mar 22, 2014 at 6:32 PM, Rhodri James <rhodri at wildebst.org.uk> wrote:
> On Sat, 22 Mar 2014 05:26:26 -0000, Rustom Mody <rustompmody at gmail.com>
> wrote:
>
>> Well almost...
>> Except that the 'loop' I am talking of is one of
>> def loop():
>>      return [yield (lambda: x) for x in [1,2,3]]
>> or
>>      return (yield (lambda: x) for x in [1,2,3])
>> or just plain ol
>>      (lambda x:  for x in [1,2,3])
>> IOW loop is an imperative construct, comprehensions are declarative
>
>
> I'm sorry, you've made a logical leap too far here.  I understand loops
> being imperative, but how are comprehensions declarative?  What do they
> declare that the loop equivalent doesn't.

I'm with Rustom on this point.  A list comprehension is a syntax for
building a list by declaring a transformation from some other iterable
object.  Forget comprehensions for a moment and think of literals.
Would you not consider this to be declarative?

    x = [1, 2, 3]

A comprehension is syntactically similar to a literal, with just a
different type of construction in mind.

Where I disagree is on the question of whether Python should therefore
break its established closure rules for lambdas that are nested inside
comprehensions versus functions that are not.  It breaks the
equivalence between comprehensions and loops, and to my mind it
introduces significant complexity for relatively little gain.


From rustompmody at gmail.com  Sat Mar 22 23:16:47 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Sat, 22 Mar 2014 20:16:47 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8412.1395542839.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
 <9edb4ea0-5faf-4369-8021-48afa9800a34@googlegroups.com>
 <op.xc5fr8pn5079vu@gnudebeest>
 <mailman.8412.1395542839.18130.python-list@python.org>
Message-ID: <83b9f241-9b0a-4e81-8829-e1726c509471@googlegroups.com>

On Sunday, March 23, 2014 8:16:28 AM UTC+5:30, Ian wrote:
> On Sat, Mar 22, 2014 at 6:32 PM, Rhodri James wrote:
> > wrote:
> >> Well almost...
> >> Except that the 'loop' I am talking of is one of
> >> def loop():
> >>      return [yield (lambda: x) for x in [1,2,3]]
> >> or
> >>      return (yield (lambda: x) for x in [1,2,3])
> >> or just plain ol
> >>      (lambda x:  for x in [1,2,3])
> >> IOW loop is an imperative construct, comprehensions are declarative
> > I'm sorry, you've made a logical leap too far here.  I understand loops
> > being imperative, but how are comprehensions declarative?  What do they
> > declare that the loop equivalent doesn't.

> I'm with Rustom on this point.  A list comprehension is a syntax for
> building a list by declaring a transformation from some other iterable
> object.  Forget comprehensions for a moment and think of literals.
> Would you not consider this to be declarative?

>     x = [1, 2, 3]

> A comprehension is syntactically similar to a literal, with just a
> different type of construction in mind.

Aha! Very elegantly put!

> Where I disagree is on the question of whether Python should therefore
> break its established closure rules for lambdas that are nested inside
> comprehensions versus functions that are not.

No... see below

> It breaks the
> equivalence between comprehensions and loops, and to my mind it
> introduces significant complexity for relatively little gain.

[I am not completely sure whether the following can be proved/is true]

1. One can change lambda's closure rules which would amount to
"significant complexity for relatively little gain"

2. One can change comprehension rules to not reassign to the 
running comprehension running varible but to rebind, using a recursive
function as the simulation of the comprehension rather than a for loop

3. 2 is semantically equivalent to 1
   - trivially for normal (ie non-lambda containing) expressions
   - and also for lambda containing expressions if your 
     default-argument trick is implemented by the python compiler
     [This is the claim I am not completely sure of and would love to hear 
     of/if counter examples]

Assuming its true:

One *semantically specifies* a comprehension with a recursive function, 
not a for loop

One *implements* a comprehension with the standard use of append
method inside a for as the expansion of a comprehension with the extra
caveat that interior lambdas are automatically wrapped inside a
default-argument binding for all outer comprehension variables.

A vanilla python programmer need not know anything about this any
more than a vanilla C programmer knows about
- strength reduction
- code hoisting
- loop unrolling
etc

that goes on inside an optimizing C compiler


From ian.g.kelly at gmail.com  Sat Mar 22 23:47:42 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 22 Mar 2014 21:47:42 -0600
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <83b9f241-9b0a-4e81-8829-e1726c509471@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
 <9edb4ea0-5faf-4369-8021-48afa9800a34@googlegroups.com>
 <op.xc5fr8pn5079vu@gnudebeest>
 <mailman.8412.1395542839.18130.python-list@python.org>
 <83b9f241-9b0a-4e81-8829-e1726c509471@googlegroups.com>
Message-ID: <CALwzidnqPLDyt+9oq5mTXiR_dX-tyqtLfEAOU=aOMVwupCBaVA@mail.gmail.com>

On Sat, Mar 22, 2014 at 9:16 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> [I am not completely sure whether the following can be proved/is true]
>
> 1. One can change lambda's closure rules which would amount to
> "significant complexity for relatively little gain"
>
> 2. One can change comprehension rules to not reassign to the
> running comprehension running varible but to rebind, using a recursive
> function as the simulation of the comprehension rather than a for loop
>
> 3. 2 is semantically equivalent to 1

Well, if you accept that 1) amounts to significant complexity for
relatively little gain, and if 2) is semantically equivalent to 1),
then it follows that 2) also amounts to significant complexity for
relatively little gain.  My statement was in regard to the complexity
of the language, not the implementation of the language.

>    - trivially for normal (ie non-lambda containing) expressions
>    - and also for lambda containing expressions if your
>      default-argument trick is implemented by the python compiler
>      [This is the claim I am not completely sure of and would love to hear
>      of/if counter examples]

The disadvantage of the default argument trick is that it does modify
the function's signature, by adding an extra argument with a default,
so they're not entirely equivalent.

> Assuming its true:
>
> One *semantically specifies* a comprehension with a recursive function,
> not a for loop

The problem with this is a cognitive one.  The comprehension *looks
like* a for loop, not a recursive function.  It is natural to reason
about it as if it were a for loop, not a recursive function.  This is
that added complexity I was talking about.

> A vanilla python programmer need not know anything about this any
> more than a vanilla C programmer knows about
> - strength reduction
> - code hoisting
> - loop unrolling
> etc
>
> that goes on inside an optimizing C compiler

Until they go to unroll their comprehension into a for loop because
they need to add some imperative construct to it, and their code
breaks as a result.  From there you'll get the programmers who will
add functions with side effects to their comprehensions because they
want the comprehension binding behavior while still performing
imperative tasks within the loop.


From marko at pacujo.net  Sun Mar 23 06:22:11 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 23 Mar 2014 12:22:11 +0200
Subject: Reading in cooked mode
References: <CAPTjJmq-DkLxwAva_pyZ2YB7H4qV5RnzsXAJQDfPVdYhT8ffOw@mail.gmail.com>
 <mailman.8411.1395541003.18130.python-list@python.org>
Message-ID: <87eh1tjju4.fsf@elektro.pacujo.net>

Cameron Simpson <cs at zip.com.au>:

> Plenty of people use editors that consider end-of-line to be a
> separator and not a terminator, leading to supposed text files lacking
> trailing newlines (or end-of-line of OS).

I use an editor (emacs) that considers the end-of-line to be a byte
among others.

> I consider this sloppy and error prone.

If any editor, emacs is smart, but it generally doesn't insert
characters on its own. I like it that way.

> So I'm happy to write code that errors if a line lacks a trailing
> newline, and thus I consider the newline to be an intergral part of
> the line.

For sure, any file reader must think the situation through. Note, for
example, that CPython doesn't require the source code file to end in a
newline.


Marko


From jt at toerring.de  Sun Mar 23 09:07:11 2014
From: jt at toerring.de (Jens Thoms Toerring)
Date: 23 Mar 2014 13:07:11 GMT
Subject: Help needed to create a Python extension library for an existing
 shared memory hash table library
References: <ba423f7b-dd9a-49d0-a37a-9fe51541fe16@googlegroups.com>
Message-ID: <bp84jtFpbfuU1@mid.uni-berlin.de>

Simon Hardy-Francis <simonhf at gmail.com> wrote:
> Hi Python fans, I just released my first open source project ever called
> SharedHashFile [1]. It's a shared memory hash table written in C. Some guy
> on Quora asked [2] whether there's an extension library for Python coming
> out. I would like to do one but I know little about Python. I was wondering
> if anybody in this group has experience writing extension libraries for
> Python?

There are, as far as I know, a number of tools that can help you
to create extension modules from C/C++ libraries (i.e. Python bin-
dings for the library). One that I have used successfully with a
largish C++ library of mine is shortly described here

http://www.riverbankcomputing.com/software/sip/intro

and the documentation and download are at

http://pyqt.sourceforge.net/Docs/sip4/
http://www.riverbankcomputing.com/software/sip/download

Since I haven't used any of the alternatives I can't comment on
how good they are. A list of them can be found here

https://wiki.python.org/moin/IntegratingPythonWithOtherLanguages

                               Regards, Jens
-- 
  \   Jens Thoms Toerring  ___      jt at toerring.de
   \__________________________      http://toerring.de


From rustompmody at gmail.com  Sun Mar 23 09:40:26 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Sun, 23 Mar 2014 06:40:26 -0700 (PDT)
Subject: Help needed to create a Python extension library for an existing
 shared memory hash table library
In-Reply-To: <bp84jtFpbfuU1@mid.uni-berlin.de>
References: <ba423f7b-dd9a-49d0-a37a-9fe51541fe16@googlegroups.com>
 <bp84jtFpbfuU1@mid.uni-berlin.de>
Message-ID: <c0ce1362-817b-4095-9c2e-f9334a0e7702@googlegroups.com>

On Sunday, March 23, 2014 6:37:11 PM UTC+5:30, Jens Thoms Toerring wrote:
> Simon Hardy-Francis  wrote:
> > Hi Python fans, I just released my first open source project ever called
> > SharedHashFile [1]. It's a shared memory hash table written in C. Some guy
> > on Quora asked [2] whether there's an extension library for Python coming
> > out. I would like to do one but I know little about Python. I was wondering
> > if anybody in this group has experience writing extension libraries for
> > Python?

> There are, as far as I know, a number of tools that can help you
> to create extension modules from C/C++ libraries (i.e. Python bin-
> dings for the library). One that I have used successfully with a
> largish C++ library of mine is shortly described here

> http://www.riverbankcomputing.com/software/sip/intro

> and the documentation and download are at

> http://pyqt.sourceforge.net/Docs/sip4/
> http://www.riverbankcomputing.com/software/sip/download

> Since I haven't used any of the alternatives I can't comment on
> how good they are. A list of them can be found here

> https://wiki.python.org/moin/IntegratingPythonWithOtherLanguages

Thats an old looking list -- pyrex is on, boost is not
Worst of all the basic builting extending/embedding seems to be
not mentioned!

Heres a list I posted recently
https://mail.python.org/pipermail/python-list/2013-June/650250.html

If it looks ok, maybe it should go up on that wiki


From azt113 at gmail.com  Sun Mar 23 10:00:55 2014
From: azt113 at gmail.com (azt113 at gmail.com)
Date: Sun, 23 Mar 2014 07:00:55 -0700 (PDT)
Subject: Install CVXOPT in Windows 64 bit
Message-ID: <e197d1a2-a21e-4d97-8820-85f5d3a41506@googlegroups.com>

Hello!
I need to urgently install CVOXPT in my pc. However, it seems that it only works under 32 bit versions. Does anyone know about a way around this?
Your advise will be much appreciated!
Ines


From fomcl at yahoo.com  Sun Mar 23 10:58:20 2014
From: fomcl at yahoo.com (Albert-Jan Roskam)
Date: Sun, 23 Mar 2014 07:58:20 -0700 (PDT)
Subject: Question about Source Control
In-Reply-To: <lglg0u$446$1@ger.gmane.org>
References: <lg6s09$irl$1@ger.gmane.org> <bortetF7t42U1@mid.individual.net>
 <lgasdj$93f$1@ger.gmane.org>
 <mailman.8270.1395195147.18130.python-list@python.org>
 <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>
 <20140322134917.080bada6@bigbox.christie.dr>
 <1395518482.78665.YahooMailNeo@web163804.mail.gq1.yahoo.com>
 <lglg0u$446$1@ger.gmane.org>
Message-ID: <1395586700.55921.YahooMailNeo@web163806.mail.gq1.yahoo.com>



________________________________
> From: Dave Angel <davea at davea.name>
>To: python-list at python.org 
>Sent: Sunday, March 23, 2014 3:18 AM
>Subject: Re: Question about Source Control
> 
>
>Albert-Jan Roskam <fomcl at yahoo.com> Wrote in message:
>> 
>
>In addition to posting in html format,? you have also set the font
>size too small for me to easily read. Reason number 12 for
>posting in text mode in a text newsgroup. 


Ooops, sorry. Below is the email again, hopefully more readable. 

One more thing (so this is not entirely a double post!). While reading these books I found that the authors were pretty religious about Clean Commits. I mean, ok, it's not a good idea to do one huge monolithic commit each month, but I felt they were exaggerating. But maybe I'm wrong and clean commits become more important when the number of collaborators get bigger. It's just so easy to fix something, and e.g. correct that typo in a docstring while you're at it.


regards,
Albert-Jan




Hi,

I can recommend the book "Pragmatic Guide to Git". Very practical and to the point:

http://www.amazon.com/Pragmatic-Guide-Git-Programmers/dp/1934356727/ref=sr_1_1/184-0142481-0484062?ie=UTF8&qid=1395518159&sr=8-1&keywords=pragmatic+guide+to+git


I addition, I read a big fat super-exhaustive book, I believe it' s this one (there are two Git books with a bat!):

http://www.amazon.com/Version-Control-Git-collaborative-development/dp/1449316387/ref=sr_1_2/184-0142481-0484062?ie=UTF8&qid=1395518159&sr=8-2&keywords=pragmatic+guide+to+git


The former is for common tasks that are not common enough to remember right away. The latter is for reference.

I only have experience with git and subversion. I like git much better. But any SCM is better than none at all.

?Regards,

Albert-Jan



From breamoreboy at yahoo.co.uk  Sun Mar 23 11:30:40 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 23 Mar 2014 15:30:40 +0000
Subject: Install CVXOPT in Windows 64 bit
In-Reply-To: <e197d1a2-a21e-4d97-8820-85f5d3a41506@googlegroups.com>
References: <e197d1a2-a21e-4d97-8820-85f5d3a41506@googlegroups.com>
Message-ID: <lgmumn$7km$1@ger.gmane.org>

On 23/03/2014 14:00, azt113 at gmail.com wrote:
> Hello!
> I need to urgently install CVOXPT in my pc. However, it seems that it only works under 32 bit versions. Does anyone know about a way around this?
> Your advise will be much appreciated!
> Ines
>

http://www.lfd.uci.edu/~gohlke/pythonlibs/#cvxopt

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rborole06 at gmail.com  Sun Mar 23 13:09:09 2014
From: rborole06 at gmail.com (rborole06 at gmail.com)
Date: Sun, 23 Mar 2014 10:09:09 -0700 (PDT)
Subject: python installation on windows
Message-ID: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>

Hi Everybody

actually i want to run python on web browser. I downloaded python and installed but i'm not able to run it in browser but it running using command prompt. so i trying to install mod_wsgi 3.4. So i downloaded precompiled version mod_wsgi-3.4.ap22.win32-py2.6 and copied mod_wsgi.so file to C:\wamp\bin\apache\Apache2.2.11\modules after i'm trying to run .\configure on path C:\Documents and Settings\Rahul\Desktop\mod_wsgi-3.4.ap22.win32-py2.6 but it giving me error that .\configure is not recognized as internal or external command.

So please suggest me what can i do for that, i'm so beginner to python and installing and configuring modules for apache.

Thanks
Rahul


From teddybubu at gmail.com  Sun Mar 23 13:29:40 2014
From: teddybubu at gmail.com (tad na)
Date: Sun, 23 Mar 2014 10:29:40 -0700 (PDT)
Subject: help with for loop----python 2.7.2
In-Reply-To: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
References: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
Message-ID: <03c8b5d0-363e-4287-80d0-a43b0266f2a3@googlegroups.com>

On Saturday, March 22, 2014 6:21:30 AM UTC-5, tad na wrote:
> I am trying to get all the element data from the rss below.
> 
> The only thing I am pulling is the first element.
 
> I don't understand why the for loop does not go through the entire rss.

> Here is my code....
> try:
>     from urllib2 import urlopen
> except ImportError:
>     from urllib.request import urlopen  
> from bs4 import BeautifulSoup 
> soup = BeautifulSoup(urlopen('http://bl.ocks.org/mbostock.rss'))
> #print soup.find_all('item')
> #print (soup)
> for item in soup.find_all('item'):
> #for item in soup:    
>     title = soup.find('title').text    
>     link = soup.find('link').text
>     item = soup.find('item').text
>     print item
>     print title
>     print link
OK . second problem :)
I can print the date.  not sure how to do this one..
try:
    from urllib2 import urlopen
except ImportError:
    from urllib.request import urlopen 
import urllib2
from bs4 import BeautifulSoup

soup = BeautifulSoup(urlopen('http://bl.ocks.org/mbostock.rss'))
#print soup.find_all('item')
#print (soup)
data = soup.find_all("item")

x=0
for item in soup.find_all('item'):
    title = item.find('title').text    
    link = item.find('link').text
    date = item.find('pubDate')
   # print date
    print('+++++++++++++++++')
    print data[x].title.text
    print data[x].link.text
    print data[x].guid.text
    print data[x].pubDate
    x = x + 1


From teddybubu at gmail.com  Sun Mar 23 13:30:27 2014
From: teddybubu at gmail.com (tad na)
Date: Sun, 23 Mar 2014 10:30:27 -0700 (PDT)
Subject: help with for loop----python 2.7.2
In-Reply-To: <03c8b5d0-363e-4287-80d0-a43b0266f2a3@googlegroups.com>
References: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
 <03c8b5d0-363e-4287-80d0-a43b0266f2a3@googlegroups.com>
Message-ID: <32858d81-7dcf-45de-af10-6157068f15af@googlegroups.com>

On Sunday, March 23, 2014 12:29:40 PM UTC-5, tad na wrote:
> On Saturday, March 22, 2014 6:21:30 AM UTC-5, tad na wrote:
> 
> > I am trying to get all the element data from the rss below.
> 
> > 
> 
> > The only thing I am pulling is the first element.
> 
>  
> 
> > I don't understand why the for loop does not go through the entire rss.
> 
> 
> 
> > Here is my code....
> 
> > try:
> 
> >     from urllib2 import urlopen
> 
> > except ImportError:
> 
> >     from urllib.request import urlopen  
> 
> > from bs4 import BeautifulSoup 
> 
> > soup = BeautifulSoup(urlopen('http://bl.ocks.org/mbostock.rss'))
> 
> > #print soup.find_all('item')
> 
> > #print (soup)
> 
> > for item in soup.find_all('item'):
> 
> > #for item in soup:    
> 
> >     title = soup.find('title').text    
> 
> >     link = soup.find('link').text
> 
> >     item = soup.find('item').text
> 
> >     print item
> 
> >     print title
> 
> >     print link
> 
> OK . second problem :)
> 
> I can print the date.  not sure how to do this one..
> 
> try:
> 
>     from urllib2 import urlopen
> 
> except ImportError:
> 
>     from urllib.request import urlopen 
> 
> import urllib2
> 
> from bs4 import BeautifulSoup
> 
> 
> 
> soup = BeautifulSoup(urlopen('http://bl.ocks.org/mbostock.rss'))
> 
> #print soup.find_all('item')
> 
> #print (soup)
> 
> data = soup.find_all("item")
> 
> 
> 
> x=0
> 
> for item in soup.find_all('item'):
> 
>     title = item.find('title').text    
> 
>     link = item.find('link').text
> 
>     date = item.find('pubDate')
> 
>    # print date
> 
>     print('+++++++++++++++++')
> 
>     print data[x].title.text
> 
>     print data[x].link.text
> 
>     print data[x].guid.text
> 
>     print data[x].pubDate
> 
>     x = x + 1

meant to say CANNOT print the date


From teddybubu at gmail.com  Sun Mar 23 13:33:02 2014
From: teddybubu at gmail.com (tad na)
Date: Sun, 23 Mar 2014 10:33:02 -0700 (PDT)
Subject: python installation on windows
In-Reply-To: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
Message-ID: <c7619a46-3c79-4eb8-9383-0fb720d6c8f5@googlegroups.com>

On Sunday, March 23, 2014 12:09:09 PM UTC-5, rbor... at gmail.com wrote:
> Hi Everybody
> 
> 
> 
> actually i want to run python on web browser. I downloaded python and installed but i'm not able to run it in browser but it running using command prompt. so i trying to install mod_wsgi 3.4. So i downloaded precompiled version mod_wsgi-3.4.ap22.win32-py2.6 and copied mod_wsgi.so file to C:\wamp\bin\apache\Apache2.2.11\modules after i'm trying to run .\configure on path C:\Documents and Settings\Rahul\Desktop\mod_wsgi-3.4.ap22.win32-py2.6 but it giving me error that .\configure is not recognized as internal or external command.
> 
> 
> 
> So please suggest me what can i do for that, i'm so beginner to python and installing and configuring modules for apache.
> 
> 
> 
> Thanks
> 
> Rahul

To set up a web browser:
1.open a dos window
2.navigate to dir you want "served"
3.type "python -m SimpleHTTPServer 8888 &."


From breamoreboy at yahoo.co.uk  Sun Mar 23 13:40:04 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 23 Mar 2014 17:40:04 +0000
Subject: help with for loop----python 2.7.2
In-Reply-To: <32858d81-7dcf-45de-af10-6157068f15af@googlegroups.com>
References: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
 <03c8b5d0-363e-4287-80d0-a43b0266f2a3@googlegroups.com>
 <32858d81-7dcf-45de-af10-6157068f15af@googlegroups.com>
Message-ID: <lgn69b$vm$1@ger.gmane.org>

On 23/03/2014 17:30, tad na wrote:

Would you please use the mailing list 
https://mail.python.org/mailman/listinfo/python-list or read and action 
this https://wiki.python.org/moin/GoogleGroupsPython to prevent us 
seeing double line spacing and single line paragraphs, thanks.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ian.g.kelly at gmail.com  Sun Mar 23 13:49:11 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 23 Mar 2014 11:49:11 -0600
Subject: help with for loop----python 2.7.2
In-Reply-To: <03c8b5d0-363e-4287-80d0-a43b0266f2a3@googlegroups.com>
References: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
 <03c8b5d0-363e-4287-80d0-a43b0266f2a3@googlegroups.com>
Message-ID: <CALwzidmA=aimxnpSWBVynnq=gLFD_igBjh9DbkO=8d6WNJ1Ydg@mail.gmail.com>

On Mar 23, 2014 11:31 AM, "tad na" <teddybubu at gmail.com> wrote:
> OK . second problem :)
> I can print the date.  not sure how to do this one..

Why not? What happens when you try?

> try:
>     from urllib2 import urlopen
> except ImportError:
>     from urllib.request import urlopen
> import urllib2
> from bs4 import BeautifulSoup
>
> soup = BeautifulSoup(urlopen('http://bl.ocks.org/mbostock.rss'))
> #print soup.find_all('item')
> #print (soup)
> data = soup.find_all("item")
>
> x=0
> for item in soup.find_all('item'):
>     title = item.find('title').text
>     link = item.find('link').text
>     date = item.find('pubDate')
>    # print date
>     print('+++++++++++++++++')
>     print data[x].title.text
>     print data[x].link.text
>     print data[x].guid.text
>     print data[x].pubDate
>     x = x + 1

data[x] should be the same object as item, no? If you want to keep track of
the current iteration index, a cleaner way to do that is by using enumerate:

    for x, item in enumerate(soup.find_all('item')):

As far as printing the pubDate goes, why not start by getting its text
property as you do with the other tags? From there you can either print the
string out directly or parse it into a datetime object.
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From teddybubu at gmail.com  Sun Mar 23 13:49:12 2014
From: teddybubu at gmail.com (tad na)
Date: Sun, 23 Mar 2014 10:49:12 -0700 (PDT)
Subject: help with for loop----python 2.7.2
In-Reply-To: <mailman.8417.1395596423.18130.python-list@python.org>
References: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
 <03c8b5d0-363e-4287-80d0-a43b0266f2a3@googlegroups.com>
 <32858d81-7dcf-45de-af10-6157068f15af@googlegroups.com>
 <mailman.8417.1395596423.18130.python-list@python.org>
Message-ID: <1bd3b586-b3ed-4d18-8d68-26a2144f6163@googlegroups.com>

On Sunday, March 23, 2014 12:40:04 PM UTC-5, Mark Lawrence wrote:
> On 23/03/2014 17:30, tad na wrote:
> Would you please use the mailing list 
> https://mail.python.org/mailman/listinfo/python-list or read and action 
> this https://wiki.python.org/moin/GoogleGroupsPython to prevent us 
> seeing double line spacing and single line paragraphs, thanks.
> -- 
> My fellow Pythonistas, ask not what our language can do for you, ask 
> what you can do for our language.
> Mark Lawrence
> ---
> This email is free from viruses and malware because avast! Antivirus protection is active.
> http://www.avast.com

mark not sure what i did wrong. The double line in the code is mine.
it helps me keep things separate.


From breamoreboy at yahoo.co.uk  Sun Mar 23 14:43:59 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sun, 23 Mar 2014 18:43:59 +0000
Subject: help with for loop----python 2.7.2
In-Reply-To: <32858d81-7dcf-45de-af10-6157068f15af@googlegroups.com>
References: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
 <03c8b5d0-363e-4287-80d0-a43b0266f2a3@googlegroups.com>
 <32858d81-7dcf-45de-af10-6157068f15af@googlegroups.com>
Message-ID: <lgna17$9p0$1@ger.gmane.org>

On 23/03/2014 17:30, tad na wrote:
> On Sunday, March 23, 2014 12:29:40 PM UTC-5, tad na wrote:
>> On Saturday, March 22, 2014 6:21:30 AM UTC-5, tad na wrote:
>>
>>> I am trying to get all the element data from the rss below.
>>
>>>
>>
>>> The only thing I am pulling is the first element.
>>
>>
>>
>>> I don't understand why the for loop does not go through the entire rss.
>>
>>
>>
>>> Here is my code....

I've snipped the bulk of the message, but imagine what the above looks 
like when its been back and forth through gg a few times, it's 
effectively unreadable.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From teddybubu at gmail.com  Sun Mar 23 17:07:28 2014
From: teddybubu at gmail.com (tad na)
Date: Sun, 23 Mar 2014 14:07:28 -0700 (PDT)
Subject: python installation on windows
In-Reply-To: <c7619a46-3c79-4eb8-9383-0fb720d6c8f5@googlegroups.com>
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
 <c7619a46-3c79-4eb8-9383-0fb720d6c8f5@googlegroups.com>
Message-ID: <73a660da-9dd8-4104-ae9c-ba1788ae1d60@googlegroups.com>

On Sunday, March 23, 2014 12:33:02 PM UTC-5, tad na wrote:
> On Sunday, March 23, 2014 12:09:09 PM UTC-5, rbor... at gmail.com wrote:
> > Hi Everybody
> > actually i want to run python on web browser. I downloaded python and installed but i'm not able to run it in browser but it running using command prompt. so i trying to install mod_wsgi 3.4. So i downloaded precompiled version mod_wsgi-3.4.ap22.win32-py2.6 and copied mod_wsgi.so file to C:\wamp\bin\apache\Apache2.2.11\modules after i'm trying to run .\configure on path C:\Documents and Settings\Rahul\Desktop\mod_wsgi-3.4.ap22.win32-py2.6 but it giving me error that .\configure is not recognized as internal or external command.

> > So please suggest me what can i do for that, i'm so beginner to python and installing and configuring modules for apache.

> > Thanks

> > Rahul
> To set up a web browser:
 
> 1.open a dos window
> 2.navigate to dir you want "served"
> 3.type "python -m SimpleHTTPServer 8888 &."
4. open browser and type http://localhost:8888/


From teddybubu at gmail.com  Sun Mar 23 17:51:19 2014
From: teddybubu at gmail.com (tad na)
Date: Sun, 23 Mar 2014 14:51:19 -0700 (PDT)
Subject: help with for loop----python 2.7.2
In-Reply-To: <mailman.8418.1395596955.18130.python-list@python.org>
References: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
 <03c8b5d0-363e-4287-80d0-a43b0266f2a3@googlegroups.com>
 <mailman.8418.1395596955.18130.python-list@python.org>
Message-ID: <5f8a6cae-4e84-4748-beb1-fd931b187e4e@googlegroups.com>

On Sunday, March 23, 2014 12:49:11 PM UTC-5, Ian wrote:
> On Mar 23, 2014 11:31 AM, "tad na" <tedd... at gmail.com> wrote:
 
> > OK . second problem :)

> > I can print the date. ?not sure how to do this one..
> Why not? What happens when you try?
> > try:
> > ? ? from urllib2 import urlopen

> > except ImportError:
> > ? ? from urllib.request import urlopen
> > import urllib2
> > from bs4 import BeautifulSoup

> > soup = BeautifulSoup(urlopen('http://bl.ocks.org/mbostock.rss'))
> > #print soup.find_all('item')
> > #print (soup)
> > data = soup.find_all("item")
> > x=0
> > for item in soup.find_all('item'):
> > ? ? title = item.find('title').text
> > ? ? link = item.find('link').text
> > ? ? date = item.find('pubDate')
> > ? ?# print date
> > ? ? print('+++++++++++++++++')
> > ? ? print data[x].title.text
> > ? ? print data[x].link.text
> > ? ? print data[x].guid.text
> > ? ? print data[x].pubDate
> > ? ? x = x + 1
> data[x] should be the same object as item, no? If you want to keep track of the current iteration index, a cleaner way to do that is by using enumerate:

> ??? for x, item in enumerate(soup.find_all('item')):
 
> As far as printing the pubDate goes, why not start by getting its text property as you do with the other tags? From there you can either print the string out directly or parse it into a datetime object.

This is the error I get with 
1. print data[x].pubDate.text
    AttributeError: 'NoneType' object has no attribute 'text'
2. print data[x].pubDate
    It results in "None"




From ben+python at benfinney.id.au  Sun Mar 23 18:39:09 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 24 Mar 2014 09:39:09 +1100
Subject: help with for loop----python 2.7.2
References: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
Message-ID: <85k3bksfoy.fsf@benfinney.id.au>

teddybubu at gmail.com writes:

> I am trying to get all the element data from the rss below.

[?]

> from bs4 import BeautifulSoup 
>
> soup = BeautifulSoup(urlopen('http://bl.ocks.org/mbostock.rss'))

RSS is not HTML; so BeautifulSoup is not a good tool to use for parsing
RSS.

Instead, you will do better if you use one of the libraries already
written for RSS parsing <URL:https://wiki.python.org/moin/RssLibraries>.

-- 
 \                                             ?To be is to do? ?Plato |
  `\                                       ?To do is to be? ?Aristotle |
_o__)                                        ?Do be do be do? ?Sinatra |
Ben Finney



From ian.g.kelly at gmail.com  Sun Mar 23 18:44:41 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 23 Mar 2014 16:44:41 -0600
Subject: help with for loop----python 2.7.2
In-Reply-To: <5f8a6cae-4e84-4748-beb1-fd931b187e4e@googlegroups.com>
References: <84eb4c69-d43d-4777-8a99-34eed9be73d6@googlegroups.com>
 <03c8b5d0-363e-4287-80d0-a43b0266f2a3@googlegroups.com>
 <mailman.8418.1395596955.18130.python-list@python.org>
 <5f8a6cae-4e84-4748-beb1-fd931b187e4e@googlegroups.com>
Message-ID: <CALwzidmCPPKR0xksXDtTjxvMRjek38ysomayc7Dsb2roi6v0kg@mail.gmail.com>

On Mar 23, 2014 3:56 PM, "tad na" <teddybubu at gmail.com> wrote:
>
> This is the error I get with
> 1. print data[x].pubDate.text
>     AttributeError: 'NoneType' object has no attribute 'text'
> 2. print data[x].pubDate
>     It results in "None"

So the problem is that it's not even finding the pubDate tag in the first
place. Some sites on the Web suggest that beautiful soup normalizes all
tags to lowercase; try looking for the pubdate tag instead.
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From rosuav at gmail.com  Sun Mar 23 18:56:02 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 09:56:02 +1100
Subject: Question about Source Control
In-Reply-To: <1395586700.55921.YahooMailNeo@web163806.mail.gq1.yahoo.com>
References: <lg6s09$irl$1@ger.gmane.org> <bortetF7t42U1@mid.individual.net>
 <lgasdj$93f$1@ger.gmane.org>
 <mailman.8270.1395195147.18130.python-list@python.org>
 <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>
 <20140322134917.080bada6@bigbox.christie.dr>
 <1395518482.78665.YahooMailNeo@web163804.mail.gq1.yahoo.com>
 <lglg0u$446$1@ger.gmane.org>
 <1395586700.55921.YahooMailNeo@web163806.mail.gq1.yahoo.com>
Message-ID: <CAPTjJmpotXCzkB3NMh9xnJfCVGCeAsYpz6F4VaMA0wZKdqyJQQ@mail.gmail.com>

On Mon, Mar 24, 2014 at 1:58 AM, Albert-Jan Roskam <fomcl at yahoo.com> wrote:
> One more thing (so this is not entirely a double post!). While reading these books I found that the authors were pretty religious about Clean Commits. I mean, ok, it's not a good idea to do one huge monolithic commit each month, but I felt they were exaggerating. But maybe I'm wrong and clean commits become more important when the number of collaborators get bigger. It's just so easy to fix something, and e.g. correct that typo in a docstring while you're at it.
>

It's important even with a single editor. When you go back and look at
a commit, you should be able to read the summary and know immediately
whether a particular line in it should have been edited or not.
Combining changes into a single commit makes that harder.

Commits are cheap. Do more of 'em rather than less.

ChrisA


From cs at zip.com.au  Sun Mar 23 20:19:53 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Mon, 24 Mar 2014 11:19:53 +1100
Subject: Question about Source Control
In-Reply-To: <CAPTjJmpotXCzkB3NMh9xnJfCVGCeAsYpz6F4VaMA0wZKdqyJQQ@mail.gmail.com>
References: <CAPTjJmpotXCzkB3NMh9xnJfCVGCeAsYpz6F4VaMA0wZKdqyJQQ@mail.gmail.com>
Message-ID: <20140324001953.GA70218@cskk.homeip.net>

On 24Mar2014 09:56, Chris Angelico <rosuav at gmail.com> wrote:
> On Mon, Mar 24, 2014 at 1:58 AM, Albert-Jan Roskam <fomcl at yahoo.com> wrote:
> > One more thing (so this is not entirely a double post!). While reading these books I found that the authors were pretty religious about Clean Commits. I mean, ok, it's not a good idea to do one huge monolithic commit each month, but I felt they were exaggerating. But maybe I'm wrong and clean commits become more important when the number of collaborators get bigger. It's just so easy to fix something, and e.g. correct that typo in a docstring while you're at it.
> >
> 
> It's important even with a single editor. When you go back and look at
> a commit, you should be able to read the summary and know immediately
> whether a particular line in it should have been edited or not.
> Combining changes into a single commit makes that harder.
> 
> Commits are cheap. Do more of 'em rather than less.

I'm particularly fond of "hg record" (or the similar extension, "hg
crecord"), which lets you commit just parts of a modified file.

When I'm in a debugging branch, it gradually turns into a huge diff.
"hg record" lets me commit specific parts of a diff in a single
commit. Every so often I spent a little while cleaning out related
changes that are going to stay so that the final diffness consists
of debug statements and hacks-in-progress; much smaller.

So I'll pick a file and run an "hg record that-file" and pick all
the diff parts that involve, say, removing some parameter. And in
goes a single commit with just that feature change. Lather, rinse,
repeat for other small concrete changes.

And then my "hg diff" is back to being managably readable.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

Wagner's music is better than it sounds.        - Mark Twain


From rosuav at gmail.com  Sun Mar 23 20:30:28 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 11:30:28 +1100
Subject: Question about Source Control
In-Reply-To: <20140324001953.GA70218@cskk.homeip.net>
References: <CAPTjJmpotXCzkB3NMh9xnJfCVGCeAsYpz6F4VaMA0wZKdqyJQQ@mail.gmail.com>
 <20140324001953.GA70218@cskk.homeip.net>
Message-ID: <CAPTjJmoJxBF2mgkUrKyD9DZmwGSmHHVskD9vR+exq7U49mkMmQ@mail.gmail.com>

On Mon, Mar 24, 2014 at 11:19 AM, Cameron Simpson <cs at zip.com.au> wrote:
> I'm particularly fond of "hg record" (or the similar extension, "hg
> crecord"), which lets you commit just parts of a modified file.
>
> When I'm in a debugging branch, it gradually turns into a huge diff.
> "hg record" lets me commit specific parts of a diff in a single
> commit. Every so often I spent a little while cleaning out related
> changes that are going to stay so that the final diffness consists
> of debug statements and hacks-in-progress; much smaller.
>
> So I'll pick a file and run an "hg record that-file" and pick all
> the diff parts that involve, say, removing some parameter. And in
> goes a single commit with just that feature change. Lather, rinse,
> repeat for other small concrete changes.
>
> And then my "hg diff" is back to being managably readable.
>

Absolutely agree. With git, the same functionality can be done by
making use of the staging area; you can either add an entire file (all
its changes), or do a partial add with "git add -p" or (more
conveniently, but requires a GUI) "git gui". I do that *very*
frequently. The only thing I would really like is a simple way to say
"stage/commit the lines from here to there"; with git gui, I can
either stage an entire hunk (everything until the next point where
there's enough unchanged lines that the context breaks) or a single
line (either an insertion or a removal). Gets tedious when you want to
stage half of a large hunk. But other than that, yes, the
functionality is awesome, letting you fidget your edits into readable
commits.

ChrisA


From pabloeruggeri at gmail.com  Sun Mar 23 20:35:14 2014
From: pabloeruggeri at gmail.com (pabloeruggeri at gmail.com)
Date: Sun, 23 Mar 2014 17:35:14 -0700 (PDT)
Subject: loop
Message-ID: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>

Hello, 

I'm trying to create a for loop that starts at 100 and goes to 10Mllion. The increments are like this: 100, 1000, 10000, ..... Basicaly adding a zero each iteration. I'm having problems trying to do it. Can somebody help me


From python at mrabarnett.plus.com  Sun Mar 23 20:50:55 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 24 Mar 2014 00:50:55 +0000
Subject: loop
In-Reply-To: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
Message-ID: <532F816F.1080301@mrabarnett.plus.com>

On 2014-03-24 00:35, pabloeruggeri at gmail.com wrote:
> Hello,
>
> I'm trying to create a for loop that starts at 100 and goes to
> 10Mllion. The increments are like this: 100, 1000, 10000, .....
> Basicaly adding a zero each iteration. I'm having problems trying to
> do it. Can somebody help me
>
Probably better to use a 'while' loop instead, multiplying by 10 on
each iteration until the number exceeds 10 million.


From rosuav at gmail.com  Sun Mar 23 20:52:11 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 11:52:11 +1100
Subject: loop
In-Reply-To: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
Message-ID: <CAPTjJmqodB8gfbX3=Kix6dgT_E2wyVQw4UyL8=PeLZHidTzWoA@mail.gmail.com>

On Mon, Mar 24, 2014 at 11:35 AM,  <pabloeruggeri at gmail.com> wrote:
> Hello,
>
> I'm trying to create a for loop that starts at 100 and goes to 10Mllion. The increments are like this: 100, 1000, 10000, ..... Basicaly adding a zero each iteration. I'm having problems trying to do it. Can somebody help me
>

That sounds like a logarithmic scale. Look at this:

>>> 10**2
100
>>> 10**3
1000
...
>>> 10**7
10000000

Do you know how to iterate from 2 to 7 inclusive?

ChrisA


From breamoreboy at yahoo.co.uk  Sun Mar 23 20:56:51 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 24 Mar 2014 00:56:51 +0000
Subject: loop
In-Reply-To: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
Message-ID: <lgnvsb$fkt$1@ger.gmane.org>

On 24/03/2014 00:35, pabloeruggeri at gmail.com wrote:
> Hello,
>
> I'm trying to create a for loop that starts at 100 and goes to 10Mllion. The increments are like this: 100, 1000, 10000, ..... Basicaly adding a zero each iteration. I'm having problems trying to do it. Can somebody help me
>

Start by rereading this 
http://docs.python.org/3/tutorial/controlflow.html#for-statements, give 
it another go and if you have problems post your code inline here and 
we'll help you out.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From pabloeruggeri at gmail.com  Sun Mar 23 20:57:28 2014
From: pabloeruggeri at gmail.com (pabloeruggeri at gmail.com)
Date: Sun, 23 Mar 2014 17:57:28 -0700 (PDT)
Subject: loop
In-Reply-To: <mailman.8425.1395622263.18130.python-list@python.org>
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
 <mailman.8425.1395622263.18130.python-list@python.org>
Message-ID: <fd3d0d6e-caf0-4b42-bae1-a4be752b40a9@googlegroups.com>



Thanks!! 


From bupphairodazz at yandex.ru  Sun Mar 23 20:59:20 2014
From: bupphairodazz at yandex.ru (anton)
Date: Sun, 23 Mar 2014 17:59:20 -0700 (PDT)
Subject: loop
In-Reply-To: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
Message-ID: <05924f21-0162-4d4c-84d0-016c7fdfeee1@googlegroups.com>

for i in (10**p for p in range(3, 8)):
    print(i)


From cs at zip.com.au  Sun Mar 23 21:07:13 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Mon, 24 Mar 2014 12:07:13 +1100
Subject: Question about Source Control
In-Reply-To: <CAPTjJmoJxBF2mgkUrKyD9DZmwGSmHHVskD9vR+exq7U49mkMmQ@mail.gmail.com>
References: <CAPTjJmoJxBF2mgkUrKyD9DZmwGSmHHVskD9vR+exq7U49mkMmQ@mail.gmail.com>
Message-ID: <20140324010713.GA46934@cskk.homeip.net>

On 24Mar2014 11:30, Chris Angelico <rosuav at gmail.com> wrote:
> On Mon, Mar 24, 2014 at 11:19 AM, Cameron Simpson <cs at zip.com.au> wrote:
> > I'm particularly fond of "hg record" (or the similar extension, "hg
> > crecord"), which lets you commit just parts of a modified file.
> >
> > When I'm in a debugging branch, it gradually turns into a huge diff.
> > [...] Every so often I spent a little while cleaning out related
> > changes that are going to stay so that the final diffness consists
> > of debug statements and hacks-in-progress; much smaller. [...]
> 
> Absolutely agree. With git, the same functionality can be done by
> making use of the staging area; you can either add an entire file (all
> its changes), or do a partial add with "git add -p" or (more
> conveniently, but requires a GUI) "git gui". [...]
> The only thing I would really like is a simple way to say
> "stage/commit the lines from here to there"; with git gui, I can
> either stage an entire hunk (everything until the next point where
> there's enough unchanged lines that the context breaks) or a single
> line (either an insertion or a removal). Gets tedious when you want to
> stage half of a large hunk. [...]

"hg record" has the same issue; you get to approve or ignore single
diff chunks.

However, there's no fundamental technical reason you can't pick and
choose arbitrary lines.

Based on things I've experienced use "hg record", it pretty clearly
walks the user through the diff picking/rejecting chunks, and then
temporarily replaces the target file(s) with versions containing
only the selected diff chunks, and commits the files. Then it
restores the original modified file, whose diff from the "tip" is
now reduced.

With some work, that could be done on a line-by-line basis.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

I've always been a big Greenaway fan - I've seen and enjoyed "The Falls" for
crying out loud.        - Peter Alexander Merel <pete at extro.ucc.su.OZ.AU>


From tjreedy at udel.edu  Sun Mar 23 21:26:54 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 23 Mar 2014 21:26:54 -0400
Subject: Question about Source Control
In-Reply-To: <CAPTjJmpotXCzkB3NMh9xnJfCVGCeAsYpz6F4VaMA0wZKdqyJQQ@mail.gmail.com>
References: <lg6s09$irl$1@ger.gmane.org> <bortetF7t42U1@mid.individual.net>
 <lgasdj$93f$1@ger.gmane.org>
 <mailman.8270.1395195147.18130.python-list@python.org>
 <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>
 <20140322134917.080bada6@bigbox.christie.dr>
 <1395518482.78665.YahooMailNeo@web163804.mail.gq1.yahoo.com>
 <lglg0u$446$1@ger.gmane.org>
 <1395586700.55921.YahooMailNeo@web163806.mail.gq1.yahoo.com>
 <CAPTjJmpotXCzkB3NMh9xnJfCVGCeAsYpz6F4VaMA0wZKdqyJQQ@mail.gmail.com>
Message-ID: <lgo1kp$k75$1@ger.gmane.org>

On 3/23/2014 6:56 PM, Chris Angelico wrote:
> On Mon, Mar 24, 2014 at 1:58 AM, Albert-Jan Roskam <fomcl at yahoo.com> wrote:
>> One more thing (so this is not entirely a double post!). While reading these books I found that the authors were pretty religious about Clean Commits. I mean, ok, it's not a good idea to do one huge monolithic commit each month, but I felt they were exaggerating. But maybe I'm wrong and clean commits become more important when the number of collaborators get bigger. It's just so easy to fix something, and e.g. correct that typo in a docstring while you're at it.
>>
>
> It's important even with a single editor. When you go back and look at
> a commit, you should be able to read the summary and know immediately
> whether a particular line in it should have been edited or not.
> Combining changes into a single commit makes that harder.
>
> Commits are cheap. Do more of 'em rather than less.

With multiple branches (as with 2.7, 3.4, and default for cpython) and 
multiple active developers (20?) commiting to those brances, commits are 
definitely not free. I would not exactly call them as cheap as you seem 
to imply either. That said, I have occasionally pushed interim changes 
that put code in an improved and stable state.

N. Coughlan has suggested improving the cpython infrastructure and 
procedures to reduce the cost of commits to encourage more people to 
make more commits (in the sense of more lines changed, not more pieces) 
and improve cpython faster.

--
Terry Jan Reedy



From breamoreboy at yahoo.co.uk  Sun Mar 23 21:42:23 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 24 Mar 2014 01:42:23 +0000
Subject: Question about Source Control
In-Reply-To: <lgo1kp$k75$1@ger.gmane.org>
References: <lg6s09$irl$1@ger.gmane.org> <bortetF7t42U1@mid.individual.net>
 <lgasdj$93f$1@ger.gmane.org>
 <mailman.8270.1395195147.18130.python-list@python.org>
 <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>
 <20140322134917.080bada6@bigbox.christie.dr>
 <1395518482.78665.YahooMailNeo@web163804.mail.gq1.yahoo.com>
 <lglg0u$446$1@ger.gmane.org>
 <1395586700.55921.YahooMailNeo@web163806.mail.gq1.yahoo.com>
 <CAPTjJmpotXCzkB3NMh9xnJfCVGCeAsYpz6F4VaMA0wZKdqyJQQ@mail.gmail.com>
 <lgo1kp$k75$1@ger.gmane.org>
Message-ID: <lgo2hn$m2d$1@ger.gmane.org>

On 24/03/2014 01:26, Terry Reedy wrote:
> On 3/23/2014 6:56 PM, Chris Angelico wrote:
>> On Mon, Mar 24, 2014 at 1:58 AM, Albert-Jan Roskam <fomcl at yahoo.com>
>> wrote:
>>> One more thing (so this is not entirely a double post!). While
>>> reading these books I found that the authors were pretty religious
>>> about Clean Commits. I mean, ok, it's not a good idea to do one huge
>>> monolithic commit each month, but I felt they were exaggerating. But
>>> maybe I'm wrong and clean commits become more important when the
>>> number of collaborators get bigger. It's just so easy to fix
>>> something, and e.g. correct that typo in a docstring while you're at it.
>>>
>>
>> It's important even with a single editor. When you go back and look at
>> a commit, you should be able to read the summary and know immediately
>> whether a particular line in it should have been edited or not.
>> Combining changes into a single commit makes that harder.
>>
>> Commits are cheap. Do more of 'em rather than less.
>
> With multiple branches (as with 2.7, 3.4, and default for cpython) and
> multiple active developers (20?) commiting to those brances, commits are
> definitely not free. I would not exactly call them as cheap as you seem
> to imply either. That said, I have occasionally pushed interim changes
> that put code in an improved and stable state.

And consider that this has been simplified, at one point four branches 
plus default were being supported at the same time.

>
> N. Coughlan has suggested improving the cpython infrastructure and
> procedures to reduce the cost of commits to encourage more people to
> make more commits (in the sense of more lines changed, not more pieces)
> and improve cpython faster.
>

Excellent.  The most frustrating part of CPython development from my 
viewpoint is the massive number of open issues on the bug tracker that 
have patches, but simply sit there for years doing nothing except gather 
dust.  Anything that can be done to improve this situation is IMHO long 
overdue and extremely welcome.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Sun Mar 23 22:04:54 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 13:04:54 +1100
Subject: Question about Source Control
In-Reply-To: <lgo1kp$k75$1@ger.gmane.org>
References: <lg6s09$irl$1@ger.gmane.org> <bortetF7t42U1@mid.individual.net>
 <lgasdj$93f$1@ger.gmane.org>
 <mailman.8270.1395195147.18130.python-list@python.org>
 <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>
 <20140322134917.080bada6@bigbox.christie.dr>
 <1395518482.78665.YahooMailNeo@web163804.mail.gq1.yahoo.com>
 <lglg0u$446$1@ger.gmane.org>
 <1395586700.55921.YahooMailNeo@web163806.mail.gq1.yahoo.com>
 <CAPTjJmpotXCzkB3NMh9xnJfCVGCeAsYpz6F4VaMA0wZKdqyJQQ@mail.gmail.com>
 <lgo1kp$k75$1@ger.gmane.org>
Message-ID: <CAPTjJmotL=J-humqR9xi=HerVnDjGooC74o-yXO=uQ3Xv+R9kw@mail.gmail.com>

On Mon, Mar 24, 2014 at 12:26 PM, Terry Reedy <tjreedy at udel.edu> wrote:
> With multiple branches (as with 2.7, 3.4, and default for cpython) and
> multiple active developers (20?) commiting to those brances, commits are
> definitely not free. I would not exactly call them as cheap as you seem to
> imply either. That said, I have occasionally pushed interim changes that put
> code in an improved and stable state.
>
> N. Coughlan has suggested improving the cpython infrastructure and
> procedures to reduce the cost of commits to encourage more people to make
> more commits (in the sense of more lines changed, not more pieces) and
> improve cpython faster.

When I call them cheap, what I mean is that there's little difference
between a single commit and 2-3 commits as a group. Yes, there's a bit
more difference when you're cherry-picking them to other branches, and
maybe an infrastructure/procedure change could help with that; but
once they're there in history, it doesn't hurt to have three separate
commits doing related work, keeping the distinct parts distinct.

ChrisA


From rhodri at wildebst.org.uk  Sun Mar 23 22:22:54 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Mon, 24 Mar 2014 02:22:54 -0000
Subject: python installation on windows
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
Message-ID: <op.xc7fkg2m5079vu@gnudebeest>

On Sun, 23 Mar 2014 17:09:09 -0000, <rborole06 at gmail.com> wrote:

> Hi Everybody
>
> actually i want to run python on web browser.

Actually you don't.  You want to run Python on a web server, which  
fortunately is a good deal easier.

> I downloaded python and installed but i'm not able to run it in browser  
> but it running using command prompt. so i trying to install mod_wsgi  
> 3.4. So i downloaded precompiled version mod_wsgi-3.4.ap22.win32-py2.6  
> and copied mod_wsgi.so file to C:\wamp\bin\apache\Apache2.2.11\modules  
> after i'm trying to run .\configure on path C:\Documents and  
> Settings\Rahul\Desktop\mod_wsgi-3.4.ap22.win32-py2.6 but it giving me  
> error that .\configure is not recognized as internal or external command.
>
> So please suggest me what can i do for that, i'm so beginner to python  
> and installing and configuring modules for apache.

The ".\configure" thing is for Linux installations using autotools; it's  
not going to work on Windows.

I don't run Apache on Windows, so I'm just guessing from the documentation  
here, but the mod_wsgi "Installation on Windows" page says to "follow the  
instructions for loading mod_wsgi in the Quick Installation Guide."  The  
"Quick Installation Guide" page has instructions for editing the Apache  
config files.  No mention of running ".\configure" -- why are you doing  
that?  Try just editing the config files as the documentation suggests and  
see if that works.

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From ben+python at benfinney.id.au  Sun Mar 23 22:31:01 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 24 Mar 2014 13:31:01 +1100
Subject: loop
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
Message-ID: <85zjkgqqe2.fsf@benfinney.id.au>

pabloeruggeri at gmail.com writes:

> I'm trying to create a for loop that starts at 100 and goes to
> 10Mllion. The increments are like this: 100, 1000, 10000, .....
> Basicaly adding a zero each iteration. I'm having problems trying to
> do it. Can somebody help me

Welcome.

What have you tried so far?

We're not in the practice of just writing the code for you; please show
us what you have written that we can try running it, and how it's
behaving differently from what you expect.

-- 
 \           ?Oh, I love your magazine. My favorite section is ?How To |
  `\          Increase Your Word Power?. That thing is really, really, |
_o__)                          really... good.? ?Homer, _The Simpsons_ |
Ben Finney



From rhodri at wildebst.org.uk  Sun Mar 23 22:35:45 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Mon, 24 Mar 2014 02:35:45 -0000
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
 <9edb4ea0-5faf-4369-8021-48afa9800a34@googlegroups.com>
 <op.xc5fr8pn5079vu@gnudebeest>
 <mailman.8412.1395542839.18130.python-list@python.org>
Message-ID: <op.xc7f5vuf5079vu@gnudebeest>

On Sun, 23 Mar 2014 02:46:28 -0000, Ian Kelly <ian.g.kelly at gmail.com>  
wrote:

> On Sat, Mar 22, 2014 at 6:32 PM, Rhodri James <rhodri at wildebst.org.uk>  
> wrote:
>> On Sat, 22 Mar 2014 05:26:26 -0000, Rustom Mody <rustompmody at gmail.com>
>> wrote:
>>
>>> Well almost...
>>> Except that the 'loop' I am talking of is one of
>>> def loop():
>>>      return [yield (lambda: x) for x in [1,2,3]]
>>> or
>>>      return (yield (lambda: x) for x in [1,2,3])
>>> or just plain ol
>>>      (lambda x:  for x in [1,2,3])
>>> IOW loop is an imperative construct, comprehensions are declarative
>>
>>
>> I'm sorry, you've made a logical leap too far here.  I understand loops
>> being imperative, but how are comprehensions declarative?  What do they
>> declare that the loop equivalent doesn't.
> I'm with Rustom on this point.  A list comprehension is a syntax for
> building a list by declaring a transformation from some other iterable
> object.  Forget comprehensions for a moment and think of literals.
> Would you not consider this to be declarative?
>
>    x = [1, 2, 3]

I'm not sure I would.  I look at that line of code and think of it as  
"Create a list...", very much in an imperative manner.  Then again,  
compared with C structs and typedefs and actual honest-to-God type  
declarations, there's precious little in Python I would consider truly  
declarative.

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From steve+comp.lang.python at pearwood.info  Sun Mar 23 22:37:32 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 24 Mar 2014 02:37:32 GMT
Subject: Reading in cooked mode (was Re: Python MSI not installing, log
 file showing name of a Viatnemese communist revolutionary)
References: <mailman.8409.1395538666.18130.python-list@python.org>
Message-ID: <532f9a6b$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sun, 23 Mar 2014 12:37:43 +1100, Chris Angelico wrote:

> On Sun, Mar 23, 2014 at 12:07 PM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> On Sun, 23 Mar 2014 02:09:20 +1100, Chris Angelico wrote:
>>
>>> On Sun, Mar 23, 2014 at 1:50 AM, Steven D'Aprano
>>> <steve+comp.lang.python at pearwood.info> wrote:
>>>> Line endings are terminators: they end the line. Whether you consider
>>>> the terminator part of the line or not is a matter of opinion (is the
>>>> cover of a book part of the book?) but consider this:
>>>>
>>>>     If you say that the end of lines are *not* part of the line, then
>>>>     that implies that some parts of the file are not inside any line
>>>>     at all. And that would be just weird.
>>>
>>> Not so weird IMO. A file is not a concatenation of lines; it is a
>>> stream of bytes.
>>
>> But a *text file* is a concatenation of lines. The "text file" model is
>> important enough that nearly all programming languages offer a
>> line-based interface to files, and some (Python at least, possibly
>> others) make it the default interface so that iterating over the file
>> gives you lines rather than bytes -- even in "binary" mode.
> 
> And lines are delimited entities. A text file is a sequence of lines,
> separated by certain characters.

Are they really separated, or are they terminated?

    a\nb\n

Three lines or two? If you say three, then you consider \n to be a 
separator; if you say two, you consider it a terminator.

The thing is, both points of view are valid. If \n is a terminator, then 
the above is valid text, but this may not be:

    a\nb\nc

since the last line is unterminated. (You might be generous and allow 
that every line must be terminated except possibly the last. Or you might 
be strict and consider the last line to be broken.)

In practice, most people swap between one point of view and the other 
without warning: I might say that "a\nb\n" has two lines terminated with 
\n, and then an instant later say that the file ends with a blank line, 
which means it has three lines, not two. Or you might say that "a\nb\n" 
has three lines separated by \n, and an instant later claim that the last 
line contains the letter "b". So common language about text files tends 
to be inconsistent and flip-flop between the two points of view, a bit 
like the Necker Cube optical illusion.

Given that the two points of view are legitimate and useful, how should a 
programming language treat lines? If the language treats the newline as 
separator, and strips it, then those who want to treat it as terminator 
are screwed -- you cannot tell if the last line is terminated or not. But 
if the language treats the newline as a terminator, and so part of the 
line, it is easy for the caller to remove it. The decision ought to be a 
no-brainer: keep the newline in place, let the user strip it if they 
don't want it.

Here's another thought for you: words are separated by spaces. Nobody 
ever considers the space to be part of the word[1]. I think that nearly 
everyone agrees that both "spam eggs" and "spam      eggs" contain two 
words, "spam" and "eggs". I don't think anyone would say that the second 
example includes seven words, five of which are blank. Would we like to 
say that "spam\n\n\n\n\n\neggs" contains two lines rather than seven?


 
>>> (Both interpretations make sense. I just wish the most obvious form of
>>> iteration gave the cleaner/tidier version, or at very least that there
>>> be some really obvious way to ask for lines-without-endings.)
>>
>> There is: call strip('\n') on the line after reading it. Perl and Ruby
>> spell it chomp(). Other languages may spell it differently. I don't
>> know of any language that automatically strips newlines, probably
>> because you can easily strip the newline from the line, but if the
>> language did it for you, you cannot reliably reverse it.
> 
> That's not a tidy way to iterate, that's a way to iterate and then do
> stuff. Compare:
> 
> for line in f:
>     # process line with newline
> 
> for line in f:
>     line = line.strip("\n")
>     # process line without newline, as long as it doesn't have \r\n or
>     something

With universal newline support, you can completely ignore the difference 
in platform-specific end-of-line markers. By default, Python will convert 
them to and from \n when you read or write a text file, and you'll never 
see any difference. Just program using \n in your source code, and let 
Python do the right thing. (If you need to handle end of line markers 
yourself, you can easily disable universal newline support.)

f = (line.rstrip('\n') for line in f)
for line in f:
    # process line

Everything[1] in computer science can be solved by an additional layer of 
indirection :-)


[...]
> So why is the delimiter excluded when you treat the file as CSV, but
> included when you treat the file as lines of text?

Because reading lines of text is more general than reading CSV records. 
Therefore it has to make fewer modifications to the raw content.

I once had a Pascal compiler that would insert spaces, indentation, even 
change the case of words. Regardless of what you actually typed, it would 
pretty-print your code, then write the pretty-printed output when you 
saved. Likewise, if you read in a Pascal source file from an external 
editor, then saved it, it would overwrite the original with it's pretty-
printed version. That sort of thing may or may not be appropriate for a 
high-level tool which is allowed to impose whatever structure it likes on 
its data files, but it would be completely inappropriate for a low-level 
almost-raw process (more like lightly blanched than cooked) like reading 
from a text file in Python.


>> Reading from a file is considered a low-level operation. Reading
>> individual bytes in binary mode is the lowest level; reading lines in
>> text mode is the next level, built on top of the lower binary mode. You
>> build higher protocols on top of one or the other of that mode, e.g.
>> "read a zip file" would be built on top of binary mode, "read a csv
>> file" would be built on top of text mode.
> 
> I agree that reading a binary file is the lowest level. Reading a text
> file is higher level, but to me "reading a text file" means "reading a
> binary file and decoding it into Unicode text", and not "... and
> dividing it into lines". Bear in mind that reading a CSV file can be
> built on top of a Unicode decode, but not on a line-based iteration (in
> case there are newlines inside quotes).

Of course you can build a CSV reader on top of line-based iteration. You 
just need an accumulator inside your parser: if, at the end of the line, 
you are still inside a quoted field, keep processing over the next line.


>> As a low-level protocol, you ought to be able to copy a file without
>> changing it by reading it in then writing it out:
>>
>> for blob in infile:
>>     outfile.write(blob)
>>
>>
>> ought to work whether you are in text mode or binary mode, so long as
>> the infile and outfile are opened in the same mode. If Python were to
>> strip newlines, that would no longer be the case.
> 
> All you need is a "writeln" method that re-adds the newline, and then
> it's correctly round-tripping, based on what you've already stated about
> the file: that it's a series of lines of text.

No, that can't work. If the last line of the input file lacks a line 
terminator, the writeln will add one. Let's make it simple: if your data 
file consists of only a single line, "spam", the first blob you receive 
will be "spam". If it consists of "spam\n" instead, the first blob you 
receive will also be "spam". Should you call write() or writeln()? 
Whichever you choose, you will get it wrong for some files.


> It might not be a
> byte-equivalent round-trip if you're changing newline style, any more
> than it already won't be for other reasons (file encoding, for
> instance). 

Ignore encodings and newline style. They are irrelevant. So long as the 
input and output writer use the same settings, the input will be copied 
unchanged.


> By reading the file as a series of Unicode lines, you're
> declaring that it contains lines of Unicode text, not arbitrary bytes,
> and so a valid representation of those lines of Unicode text is a
> faithful reproduction of the file. If you want a byte-for-byte identical
> file, open it in binary mode to do the copy; that's what we learn from
> FTPing files between Linux and Windows.

Both "spam" and "spam\n" are valid Unicode. By striping the newline, you 
make it impossible to distinguish them on the last line.




[1] For some definition of "nobody". Linguists consider that some words 
contain a space, e.g. "lawn tennis", "science fiction". This is called 
the open or spaced form of compound words. However, the trailing space at 
the end of the word is never considered part of the word.

[2] Except efficiency.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Sun Mar 23 23:17:11 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 14:17:11 +1100
Subject: Reading in cooked mode (was Re: Python MSI not installing, log
 file showing name of a Viatnemese communist revolutionary)
In-Reply-To: <532f9a6b$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.8409.1395538666.18130.python-list@python.org>
 <532f9a6b$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmrE9nxHddOUEAWy7q53pmose2GJ-zUCiW0p7y+M+Ge4ug@mail.gmail.com>

On Mon, Mar 24, 2014 at 1:37 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Sun, 23 Mar 2014 12:37:43 +1100, Chris Angelico wrote:
>> And lines are delimited entities. A text file is a sequence of lines,
>> separated by certain characters.
>
> Are they really separated, or are they terminated?
>
>     a\nb\n
>
> Three lines or two? If you say three, then you consider \n to be a
> separator; if you say two, you consider it a terminator.
>
> The thing is, both points of view are valid. If \n is a terminator, then
> the above is valid text, but this may not be:
>
>     a\nb\nc
>
> since the last line is unterminated. (You might be generous and allow
> that every line must be terminated except possibly the last. Or you might
> be strict and consider the last line to be broken.)

It is a problem, and the correct usage depends on context.

I'd normally say that the first consists of two lines, the first being
"a" and the second being "b", and there is no third blank line. The
first line still doesn't consist of "a\n", though. It's more like how
environment variables are provided to a C program: separated by \0 and
the last one has to be terminated too.

In some situations, you would completely ignore the "c" in the last
example. When you're watching a growing log file, buffering might mean
that you see half of a line. When you're reading MUD text from a
socket, a partial line probably means it's broken across two packets,
and the rest of the line is coming. Either way, you don't process the
"c" in case it's the beginning of a line; you wait till you see the
"\n" separator that says that you now have a complete line. Got some
out-of-band indication that there won't be any more (like an EOF
signal)? Assume that "c" is the whole line, or assume the file is
damaged, and proceed accordingly.

> Given that the two points of view are legitimate and useful, how should a
> programming language treat lines? If the language treats the newline as
> separator, and strips it, then those who want to treat it as terminator
> are screwed -- you cannot tell if the last line is terminated or not.

That's my point, though. If you want to treat a file as lines, you
usually won't care whether the last one is terminated or not. You'll
have some means of defining lines, which might mean discarding the
last, or whatever it is, but the stream "a\nb\nc" will either become
["a", "b", "c"] or ["a", "b"] or ValueError or something, and that
list of lines is really all you care about. Universal newlines, as you
mention, means that "a\r\nb\r\n" will become the exact same thing as
"a\nb\n", and there's no way to recreate that difference - because it
*does not matter*.

> Here's another thought for you: words are separated by spaces. Nobody
> ever considers the space to be part of the word[1]. I think that nearly
> everyone agrees that both "spam eggs" and "spam      eggs" contain two
> words, "spam" and "eggs". I don't think anyone would say that the second
> example includes seven words, five of which are blank. Would we like to
> say that "spam\n\n\n\n\n\neggs" contains two lines rather than seven?

Ahh, that's a tricky one. For the simple concept of iterating over the
lines in a file, I would have to say that it's seven lines, five of
which are blank, same as "spam      eggs".split(" ") returns a
seven-element list. The tricky bit is that the term "word" means
"*non-empty* sequence of characters", which means that after splitting
on spaces, you discard all empty tokens in the list; but normally
"line" does NOT have that non-empty qualifier. However, a double
newline often means "paragraph break" as opposed to "line break", so
there's additional meaning applied there; that might be four
paragraphs, the last one unterminated (and a paragraph might well be
terminated by a single newline rather than two), and in some cases
might be squished to just two paragraphs because the paragraph itself
is required to be non-empty.

> With universal newline support, you can completely ignore the difference
> in platform-specific end-of-line markers. By default, Python will convert
> them to and from \n when you read or write a text file, and you'll never
> see any difference. Just program using \n in your source code, and let
> Python do the right thing. (If you need to handle end of line markers
> yourself, you can easily disable universal newline support.)

So why should we have to explicitly disable universal newlines to undo
the folding of \r\n and \n down to a single "end of line" indication,
but automatically get handling of \n or absence at the end of the
file? Surely that's parallel. In each case, you're taking the set of
lines as your important content, and folding together distinctions
that don't matter.

> I once had a Pascal compiler that would insert spaces, indentation, even
> change the case of words. Regardless of what you actually typed, it would
> pretty-print your code, then write the pretty-printed output when you
> saved. Likewise, if you read in a Pascal source file from an external
> editor, then saved it, it would overwrite the original with it's pretty-
> printed version. That sort of thing may or may not be appropriate for a
> high-level tool which is allowed to impose whatever structure it likes on
> its data files, but it would be completely inappropriate for a low-level
> almost-raw process (more like lightly blanched than cooked) like reading
> from a text file in Python.

GW-BASIC used to do something similar, always upper-casing keywords
like "print" and "goto", and putting exactly one space between the
line number and the code; in the file that it stored on the disk, and
probably what it stored in memory, those were stored as single tokens.
Obviously the process of turning "print" into a one-byte marker and
then back into a word is lossy, so the result comes out as "PRINT"
regardless of how you typed it. Not quite the same, but it does give a
justification for the conversion (hey, it was designed so you could
work off floppy disks, so space was important), and of course the
program would run just the same.

>> I agree that reading a binary file is the lowest level. Reading a text
>> file is higher level, but to me "reading a text file" means "reading a
>> binary file and decoding it into Unicode text", and not "... and
>> dividing it into lines". Bear in mind that reading a CSV file can be
>> built on top of a Unicode decode, but not on a line-based iteration (in
>> case there are newlines inside quotes).
>
> Of course you can build a CSV reader on top of line-based iteration. You
> just need an accumulator inside your parser: if, at the end of the line,
> you are still inside a quoted field, keep processing over the next line.

Sure, but that's reaching past the line-based iteration. You can't
give it a single line and get back the split version; it has to be a
stateful parser that comprehends the whole file. But you can give it
Unicode data and have it completely ignore the byte stream that
produced it - which you can't do with, say, a zip reader.

>> All you need is a "writeln" method that re-adds the newline, and then
>> it's correctly round-tripping, based on what you've already stated about
>> the file: that it's a series of lines of text.
>
> No, that can't work. If the last line of the input file lacks a line
> terminator, the writeln will add one. Let's make it simple: if your data
> file consists of only a single line, "spam", the first blob you receive
> will be "spam". If it consists of "spam\n" instead, the first blob you
> receive will also be "spam". Should you call write() or writeln()?
> Whichever you choose, you will get it wrong for some files.

But you'll produce a file full of lines. You might not have something
perfectly identical, byte for byte, but it will have the same lines,
and the process will be idempotent.

>> It might not be a
>> byte-equivalent round-trip if you're changing newline style, any more
>> than it already won't be for other reasons (file encoding, for
>> instance).
>
> Ignore encodings and newline style. They are irrelevant. So long as the
> input and output writer use the same settings, the input will be copied
> unchanged.

Newline style IS relevant. You're saying that this will copy a file perfectly:

out = open("out", "w")
for line in open("in"):
    out.write(line)

but it wouldn't if the iteration and write stripped and recreated
newlines? Incorrect, because this version will collapse \r\n into \n.
It's still a *text file copy*. (And yes, I know about 'with'. Shut
up.) It's idempotent, not byte-for-byte perfect.

ChrisA


From rosuav at gmail.com  Sun Mar 23 23:27:32 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 14:27:32 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <op.xc7f5vuf5079vu@gnudebeest>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
 <9edb4ea0-5faf-4369-8021-48afa9800a34@googlegroups.com>
 <op.xc5fr8pn5079vu@gnudebeest>
 <mailman.8412.1395542839.18130.python-list@python.org>
 <op.xc7f5vuf5079vu@gnudebeest>
Message-ID: <CAPTjJmrsmOX89HyfgGk8ZPEBdUr_=pNi=J6aTMvnCYJ8F=VPNw@mail.gmail.com>

On Mon, Mar 24, 2014 at 1:35 PM, Rhodri James <rhodri at wildebst.org.uk> wrote:
>> Would you not consider this to be declarative?
>>
>>    x = [1, 2, 3]
>
>
> I'm not sure I would.  I look at that line of code and think of it as
> "Create a list...", very much in an imperative manner.  Then again, compared
> with C structs and typedefs and actual honest-to-God type declarations,
> there's precious little in Python I would consider truly declarative.

I'm in the declarative group here. Yes, it has to be implemented as
creating a list and adding three elements to it, but conceptually, it
means "Bind x to a new list with these elements". And as long as
that's the end result, I don't care how it's done; the interpreter's
most welcome to have a "template list" that it copies, or maybe a
literal tuple that gets passed to the list() constructor, or
whatever's most efficient.

It gets a bit messier when there's stuff with side effects, though.
This has to be a bit more imperative:

x = [foo(y), bar(y), quux(y)]

That means "Call foo, bar, and quux, in that order, each with y as an
argument, and bind x to a new list with their return values". And if
Python had a simple notation for calling a series of functions, that
could be written something like this:

funcs = [foo, bar, quux]
x = funcs(y)

which is looking more declarative again. It's now "Take this list of
functions and call them all, and bind x to a list of their return
values". (This could be done, with a callable subclass of list. Call
it a sort of "implicit map" if you like.) Python doesn't have that
syntax, but it does have this:

x = [f(y) for f in funcs]

and I'd say that's reasonably declarative; it should be read like the
previous one: "Take this list of funcs, call each one, and bind x to a
list of their return values". And I could imagine a
parallel-processing version of a list comp that functions like
multiprocessing.Pool.map() and doesn't promise order, which would
*definitely* be declarative.

ChrisA


From harrismh777 at gmail.com  Sun Mar 23 23:28:38 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sun, 23 Mar 2014 22:28:38 -0500
Subject: python installation on windows
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
 <c7619a46-3c79-4eb8-9383-0fb720d6c8f5@googlegroups.com>
 <73a660da-9dd8-4104-ae9c-ba1788ae1d60@googlegroups.com>
Message-ID: <lgo8p6$92p$1@speranza.aioe.org>

On 3/23/14 4:07 PM, tad na wrote:
>> On Sunday, March 23, 2014 12:33:02 PM UTC-5, tad na wrote:
>> To set up a web browser:

>> 1.open a dos window
>> 2.navigate to dir you want "served"
>> 3.type "python -m SimpleHTTPServer 8888&."
>> 4. open browser and type http://localhost:8888/

That is very ~cool. I learn something around here everyday.

But, the OP did not ask how to run a web server on python (above); he 
asked how to run python on a web browser (I think he meant web server).
Anyway, the PSF runs python (the interpreter) from a web server (I can 
access the python interpreter from my browser from the PSF site).

How is that done simply, is possibly what the OP wants to know (me too).

marcus



From rosuav at gmail.com  Sun Mar 23 23:32:13 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 14:32:13 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <op.xc7f5vuf5079vu@gnudebeest>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
 <9edb4ea0-5faf-4369-8021-48afa9800a34@googlegroups.com>
 <op.xc5fr8pn5079vu@gnudebeest>
 <mailman.8412.1395542839.18130.python-list@python.org>
 <op.xc7f5vuf5079vu@gnudebeest>
Message-ID: <CAPTjJmoKAVhBfBKzCK0DwZth-YdLfw0KMszO_LQoRB-wSZU9Jw@mail.gmail.com>

On Mon, Mar 24, 2014 at 1:35 PM, Rhodri James <rhodri at wildebst.org.uk> wrote:
> I'm not sure I would.  I look at that line of code and think of it as
> "Create a list...", very much in an imperative manner.  Then again, compared
> with C structs and typedefs and actual honest-to-God type declarations,
> there's precious little in Python I would consider truly declarative.

By the way: Python does have a difference between "declarative" and
"imperative".

def f(): # Imperative
    global x # Declarative
    x += 1 # Imperative

Declaratives control things, imperatives become byte code. Everything
in the byte code is imperative. "LOAD_GLOBAL" means "fetch this global
and put it on the stack". "INPLACE_ADD" means "iadd the top two stack
elements and push the result onto the stack". "STORE_GLOBAL" means
"pop the top stack element and store it in this global". Very very
imperative, and there's none of that created by the "global"
statement. So in that sense, yes, "x = [1, 2, 3]" is imperative; it
loads three constants, builds a list, and stores it. But digging into
the byte code isn't really helpful; it's much more useful to look at
the source code and how the programmer thinks about it.

ChrisA


From harrismh777 at gmail.com  Sun Mar 23 23:30:54 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sun, 23 Mar 2014 22:30:54 -0500
Subject: loop
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
 <05924f21-0162-4d4c-84d0-016c7fdfeee1@googlegroups.com>
Message-ID: <lgo8td$92p$2@speranza.aioe.org>

On 3/23/14 7:59 PM, anton wrote:
> for i in (10**p for p in range(3, 8)):
>      print(i)

Never do their home-work for them; but, in this case, what the heck.

:)


From rosuav at gmail.com  Sun Mar 23 23:35:19 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 14:35:19 +1100
Subject: python installation on windows
In-Reply-To: <lgo8p6$92p$1@speranza.aioe.org>
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
 <c7619a46-3c79-4eb8-9383-0fb720d6c8f5@googlegroups.com>
 <73a660da-9dd8-4104-ae9c-ba1788ae1d60@googlegroups.com>
 <lgo8p6$92p$1@speranza.aioe.org>
Message-ID: <CAPTjJmo-s8pQJqeCN-hEpcvkOUi65iU9OuknwHyjEsEWJy+9hA@mail.gmail.com>

On Mon, Mar 24, 2014 at 2:28 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> Anyway, the PSF runs python (the interpreter) from a web server (I can
> access the python interpreter from my browser from the PSF site).
>
> How is that done simply, is possibly what the OP wants to know (me too).

That's a much MUCH harder thing to do than running Python code in your
web server, because of trust issues. I don't know how it's set up, but
there'll be something in there to protect the server against malicious
or accidental insanity (spinning with "while True: pass", trying to
read/write files, trying to execute commands, using up all of RAM with
"x = []\nwhile True: x.append(1)", etc, etc, etc). That's actually a
very hard problem to solve, not something where you can just say
"Here, this is how to run Python via a browser".

ChrisA


From harrismh777 at gmail.com  Sun Mar 23 23:48:49 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sun, 23 Mar 2014 22:48:49 -0500
Subject: Reading in cooked mode (was Re: Python MSI not installing, log
 file showing name of a Viatnemese communist revolutionary)
References: <mailman.8409.1395538666.18130.python-list@python.org>
 <532f9a6b$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8433.1395631040.18130.python-list@python.org>
Message-ID: <lgo9v1$b3i$1@speranza.aioe.org>

On 3/23/14 10:17 PM, Chris Angelico wrote:
> Newline style IS relevant. You're saying that this will copy a file perfectly:
>
> out = open("out", "w")
> for line in open("in"):
>      out.write(line)
>
> but it wouldn't if the iteration and write stripped and recreated
> newlines? Incorrect, because this version will collapse \r\n into \n.
> It's still a *text file copy*. (And yes, I know about 'with'. Shut
> up.) It's idempotent, not byte-for-byte perfect.

Which was my point in the first place about new-line standards. We all 
know why its important to collapse \r\n into \n,  but why(?) in a 
general way would this be the universal desired end? (rhetorical)  Your 
example of byte-for-byte perfect copy is one good case (they are not). 
Another might be controller code (maybe ancient) where the \r is 
'required' and collapsing it to \n won't work on the device (tty, or 
other).

There does need to be a text file standard where what is desired is a 
file of "lines". Iterating over the file object should return the 
"lines" on any system platform, without the user being required to strip 
off the line-end (newline  \n) delimiter U+000a. The delimiter does not 
matter.

What python has done by collapsing the \r\n into \n is to hide the real 
problem (non standard delimiters between platforms) and in the process 
actually 'removes' possibly important information  (\r). {lossy}

We don't really use real tty devices any longer which require one code 
to bring the print head carriage back (\r) and one code to index the 
paper platten (\n).  Screen I/O doesn't work that way any longer either. 
Its time to standardize the newline and/or file text line end delimiters.

marcus


From rustompmody at gmail.com  Mon Mar 24 00:14:20 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Sun, 23 Mar 2014 21:14:20 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8434.1395631654.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
 <9edb4ea0-5faf-4369-8021-48afa9800a34@googlegroups.com>
 <op.xc5fr8pn5079vu@gnudebeest>
 <mailman.8412.1395542839.18130.python-list@python.org>
 <op.xc7f5vuf5079vu@gnudebeest>
 <mailman.8434.1395631654.18130.python-list@python.org>
Message-ID: <8a786235-3030-483c-8153-b3b420510782@googlegroups.com>

On Monday, March 24, 2014 8:57:32 AM UTC+5:30, Chris Angelico wrote:
> On Mon, Mar 24, 2014 at 1:35 PM, Rhodri James  wrote:
> >> Would you not consider this to be declarative?
> >>    x = [1, 2, 3]
> > I'm not sure I would.  I look at that line of code and think of it as
> > "Create a list...", very much in an imperative manner.  Then again, compared
> > with C structs and typedefs and actual honest-to-God type declarations,
> > there's precious little in Python I would consider truly declarative.

> I'm in the declarative group here. Yes, it has to be implemented as
> creating a list and adding three elements to it, but conceptually, it
> means "Bind x to a new list with these elements". And as long as
> that's the end result, I don't care how it's done; the interpreter's
> most welcome to have a "template list" that it copies, or maybe a
> literal tuple that gets passed to the list() constructor, or
> whatever's most efficient.

> It gets a bit messier when there's stuff with side effects, though.
> This has to be a bit more imperative:

> x = [foo(y), bar(y), quux(y)]

> That means "Call foo, bar, and quux, in that order, each with y as an
> argument, and bind x to a new list with their return values". And if
> Python had a simple notation for calling a series of functions, that
> could be written something like this:

> funcs = [foo, bar, quux]
> x = funcs(y)

> which is looking more declarative again. It's now "Take this list of
> functions and call them all, and bind x to a list of their return
> values". (This could be done, with a callable subclass of list. Call
> it a sort of "implicit map" if you like.) Python doesn't have that
> syntax, but it does have this:

> x = [f(y) for f in funcs]

> and I'd say that's reasonably declarative; it should be read like the
> previous one: "Take this list of funcs, call each one, and bind x to a
> list of their return values". And I could imagine a
> parallel-processing version of a list comp that functions like
> multiprocessing.Pool.map() and doesn't promise order, which would
> *definitely* be declarative.

You have described nicely a slippery slope!

The list
[(1, 1), (1, 2), (1, 3), (1, 4), (2, 1), (2, 2), (2, 3), (2, 4), (3, 1), (3, 2), (3, 3), (3, 4)]

looks neater written (and *thought of* ) as
[(x,y) for x in range(1,4) for y in range(1,5)]

Neat! So I play around... Change it to
[(x,y) for x in range(1,10000) for y in range(1,10000)]
and I dont have an answer but a thrashing machine!! (*)

IOW everything we write/read as programmers has a declarative and an
imperative side.
Which one one wants to focus on requires good sense and taste.

(*) Example also shows inter alia how some things -- range -- have gone from
imperative to declarative from python 2 to 3.
Some people have made languages whose main focus is generalizing this
idea to more dimensions and restrictions:
http://www.irisa.fr/cosi/Rajopadhye/dag-talk.ps


From tjreedy at udel.edu  Mon Mar 24 00:55:04 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 24 Mar 2014 00:55:04 -0400
Subject: Question about Source Control
In-Reply-To: <CAPTjJmotL=J-humqR9xi=HerVnDjGooC74o-yXO=uQ3Xv+R9kw@mail.gmail.com>
References: <lg6s09$irl$1@ger.gmane.org> <bortetF7t42U1@mid.individual.net>
 <lgasdj$93f$1@ger.gmane.org>
 <mailman.8270.1395195147.18130.python-list@python.org>
 <532dc915$0$24914$e4fe514c@dreader36.news.xs4all.nl>
 <20140322134917.080bada6@bigbox.christie.dr>
 <1395518482.78665.YahooMailNeo@web163804.mail.gq1.yahoo.com>
 <lglg0u$446$1@ger.gmane.org>
 <1395586700.55921.YahooMailNeo@web163806.mail.gq1.yahoo.com>
 <CAPTjJmpotXCzkB3NMh9xnJfCVGCeAsYpz6F4VaMA0wZKdqyJQQ@mail.gmail.com>
 <lgo1kp$k75$1@ger.gmane.org>
 <CAPTjJmotL=J-humqR9xi=HerVnDjGooC74o-yXO=uQ3Xv+R9kw@mail.gmail.com>
Message-ID: <lgodr3$fbf$1@ger.gmane.org>

On 3/23/2014 10:04 PM, Chris Angelico wrote:
> On Mon, Mar 24, 2014 at 12:26 PM, Terry Reedy <tjreedy at udel.edu> wrote:
>> With multiple branches (as with 2.7, 3.4, and default for cpython) and
>> multiple active developers (20?) commiting to those brances, commits are
>> definitely not free. I would not exactly call them as cheap as you seem to
>> imply either. That said, I have occasionally pushed interim changes that put
>> code in an improved and stable state.
>>
>> N. Coughlan has suggested improving the cpython infrastructure and
>> procedures to reduce the cost of commits to encourage more people to make
>> more commits (in the sense of more lines changed, not more pieces) and
>> improve cpython faster.
>
> When I call them cheap, what I mean is that there's little difference
> between a single commit and 2-3 commits as a group.  Yes, there's a bit
> more difference when you're cherry-picking them to other branches, and
> maybe an infrastructure/procedure change could help with that; but
> once they're there in history, it doesn't hurt to have three separate
> commits doing related work, keeping the distinct parts distinct.

Every commit to a 3.x maintenance branch (now 3.4) must be forward 
merged into the 3.(x+1) default (now the future 3.5), even if it is just 
a null merge. The point of this policy is to keep the repository in a 
coherent state. If a bug were fixed in maintenance but not default, it 
would create a regression situation, the same as if it were fixed in 
default and then broken again by a separate patch.

Part of the planned (hoped-for) change (using a system that is already 
working for another project with even more code and committers) is to 
automatically test patches on the buildbots before they are committed to 
the central repository, rather than after. Each would be tested and 
accepted or rejected separately. So each commit would have to stand on 
its own even more than now.

-- 
Terry Jan Reedy



From rosuav at gmail.com  Mon Mar 24 01:04:51 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 16:04:51 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <8a786235-3030-483c-8153-b3b420510782@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <mailman.8382.1395463877.18130.python-list@python.org>
 <9edb4ea0-5faf-4369-8021-48afa9800a34@googlegroups.com>
 <op.xc5fr8pn5079vu@gnudebeest>
 <mailman.8412.1395542839.18130.python-list@python.org>
 <op.xc7f5vuf5079vu@gnudebeest>
 <mailman.8434.1395631654.18130.python-list@python.org>
 <8a786235-3030-483c-8153-b3b420510782@googlegroups.com>
Message-ID: <CAPTjJmqReFZabuHxED635q+tUAWnOdJX42rbpgGqDrbJjZBziw@mail.gmail.com>

On Mon, Mar 24, 2014 at 3:14 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> Neat! So I play around... Change it to
> [(x,y) for x in range(1,10000) for y in range(1,10000)]
> and I dont have an answer but a thrashing machine!! (*)

Yes, because you used square brackets, which means that the list has
to be fully realized. As you comment, range changed from returning a
list to returning an iterable, and this action is similarly cheap:

>>> ((x,y) for x in range(1,10000) for y in range(1,10000))
<generator object <genexpr> at 0x7f53ed61b360>

You can take a few elements from that cheaply:

>>> [next(_),next(_),next(_)]
[(1, 1), (1, 2), (1, 3)]

If you like thinking in "lazy lists", you can probably think just as
easily with generators; you can't pull up arbitrary elements from it,
or query its length, but for many purposes a generator will do.

ChrisA


From harrismh777 at gmail.com  Mon Mar 24 01:52:52 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 00:52:52 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgoh7j$otg$1@speranza.aioe.org>

On 3/22/14 4:46 AM, Steven D'Aprano wrote:
> On Fri, 21 Mar 2014 23:51:38 -0500, Mark H Harris wrote:
>
>> Lambda is a problem, if only because it causes confusion. What's the
>> problem?  Glad you asked. The constructs DO NOT work the way most people
>> would expect them to, having limited knowledge of python!

    One of the best links for understanding what is wrong with lambda is 
here, from Guido, (by the way I agree totally with his assessment, there 
is no point really in writing it out again):

   http://www.artima.com/weblogs/viewpost.jsp?thread=98196


> Why is that a problem? Would you consider it a problem that people who
> don't understand BASIC can't understand BASIC? ("I don't get the
> difference between GOTO and GOSUB. {snip}
>
> The problem is ignorance, not the calculator, and not lambda.

    You're argument, based on analogy, is also a red herring, as well a 
straw man. Lambda is a problem of confusion for scientists and other 
mathematicians (amateur and otherwise) who may be confused because 
python's lambda does not do precisely what they might expect from other 
functional programming languages, nor does it match precisely with the 
lambda calculus. Its also confusing to sophisticated users of all 
stripes who may not be aware of "lambda" at all.

> You've told us that "most people" (which people? dentists? lawyers?
> illiterate tribesmen from the Amazon? professional programmers?) are
> surprised by lamba's behaviour, but you haven't actually told us what
> behaviour is surprising, or what "most people" expect lambda to do.
> Perhaps you ought to?

    I love your rhetoric, actually, but red herrings all . . .

    Here is a link that advocates lambda (map, filter, and reduce) as a 
very powerful construct for doing various things:  I agree:

http://www.secnetix.de/olli/Python/lambda_functions.hawk

    Its a great link, but the important sentence for this discussion is 
this unique quote, about "lambda,"

 >"This is not exactly the same as lambda in functional
> programming languages, but it is a very powerful concept . . ."

    People who understand lambda from functional languages must hassle 
with the fact that lambda is different in python, and people who do not 
understand functional programming languages (nor the lambda calculus) 
are confused by the syntax, also just what it does.


> Python is not a pure functional language, but you can write functional
> code in it. If you want a pure functional language, you know where to
> find one.

    Yes, that's obvious; but you're missing the point. Python is not a 
functional language, and implying that it can be used as one is 
misleading at best (maybe a lie at worst) just because it has a 
construct for generating a dynamic anonymous function.

> (I wonder whether, say, Haskell has the people coming along and demanding
> that it should become more like Python?)

    Another straw man.

    Well, number one, I'm not demanding anything. Number two, everyone 
who uses Haskell (for whatever reason) knows well from the start that 
its a pure functional programming language. That is the advertisement, 
and that is the expectation. No one expects anything different.

>> I can see uses for python's lambda.  But, honestly, I think python could
>> deprecate its use and in five years just remove it from the language;
>> along with filter, map, and reduce !
>
> Python could deprecate many things. It would make Python a worse language.

    How so?  Read Guido's argument above. Another way to answer this 
question is that I have been programming with Python for almost a decade 
and I've not used lambda. In fact, I have gone out of my way to NOT use 
lambda because I am fully aware that the BDFL hates it. Reduce is no 
longer in the standard library (although you can import it) and there 
are equally good ways to do what lambda was designed for without the 
hassle nor confusion.

> By the way, are you aware that lambda is *identical* to def except for
> three things?
>
> - lambda is an expression, not a statement like def;
>
> - the body of a function created with lambda is limited to a
>    single expression, not a block;
>
> - the function object created with lambda has a generic name.

    Absolutely, thank you for pointing those out !  You forgot that 
lambdas can be used in expressions while def functions may not... but 
you really have proved my point.  There is so little difference between 
the two that (for the sake of clarity and reducing confusion) it might 
be good to just remove the lambda thing altogether.  Just say'in.

> So unless the surprising behaviour about lambda that you're about to tell
> us about relates to one of those three things, I *guarantee* that
> functions created with def have the same surprising behaviour.

    No, the surprising behavior is that python lambda does not work 
exactly the way that lambda works in functional programming languages 
(see the two links provided) the confusion it creates for "normal" users 
does not warrant its inclusion in the language.

    Having said that, I must admit that I've "played" with lambda 
extensively and find it interesting from a comp sci standpoint, but, 
again, for normal users I don't think there is a really good value add 
for having it in the language.



From lepto.python at gmail.com  Mon Mar 24 01:56:51 2014
From: lepto.python at gmail.com (oyster)
Date: Mon, 24 Mar 2014 13:56:51 +0800
Subject: how? Py extension does not depend on py version
Message-ID: <CACW-qXUye_iMgD8RO7AOciq7+ehLUjyotX_5K_ZYfotY_UhyZw@mail.gmail.com>

I found an extension on this blog
http://www.cnblogs.com/DxSoft/archive/2011/04/08/2009132.html

or you can download the extension directly from
http://files.cnblogs.com/DxSoft/PyFetion.rar

I found that I can do "from DxVcl import *" in py 2.5/2.6/2.7. When I try
this in py24, a msgbox says "no python25.dll is found". However "Dependency
Walker" shows that DxVcl does not has the python??.dll dependency. Is this
a dark side of python which is not in official python doc?

So, to the end, My question is: how can I write such an extension(i.e. not
DLL foe ctypes) in C/C++?

Thanks

Lee
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From solutions.for.student at gmail.com  Mon Mar 24 02:06:03 2014
From: solutions.for.student at gmail.com (solutions.for.student at gmail.com)
Date: Sun, 23 Mar 2014 23:06:03 -0700 (PDT)
Subject: solutions manual and test bank
Message-ID: <ab834823-97d7-4abc-989d-b59b304949b6@googlegroups.com>



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Computer Organization And Architecture , 8th ed , by William Stallings
Computer Organization and Design , 4 th ed
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Computer System Architecture 3rd edition by Morris Mano
Computer-Controlled Systems 3rd edition by Karl J. Astrom
Concepts of Programming Languages 7th edition Solutions Manual by Robert Sebesta
Contemporary Linear Algebra by Howard Anton Robert C. Busby
Continuous and Discrete Signals and Systems, 2nd ed , By Samir S. Soliman and Mandyam D. Srinath
Control systems  Principles and Design 2nd Edition by Madan Gopal
Control Systems Engineering 4th edition by Norman S. Nise
Corporate Finance solution manual 6th Edition by Ross
Craig's Soil Mechanics 7th Edition
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Data and computer communications 7th edition William Stallings
Data Communications and Networking 4th edition by Behroz Forouzan
Database Management Systems 3rd edition Raghu Ramakrishnan Johannes Gehrke
Design And Analysis Of Experiments ,5 th edition 2001 , by Douglas C Montgomery
Design of Analog CMOS Integrated Circuits Behzad Razavi
Design of Machine Elements , Spotts
Design of Nonlinear Control Systems with the Highest Derivative in Feedback 1st Edition by Valery D. Yurkevich [student solution manual]
Design with Operational Amplifiers and Analog Integrated Circuits, 3rd edition by Franco, Sergio
Device Electronics for Integrated Circuits 3rd edition by Muller Kamins
Differential Equations with Boundary Value Problems 2nd Edition by JOHNPOLKING and DAVID ARNOLD
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Digital and Analog Communication Systems 7th Edition by Leon W. Couch
Digital Communication 4th edition by Proakis
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Digital Communications Fundamentals and Applications, 2nd Edition by Bernard sklar
Digital Control and state variable methods - M.Gopal
Digital Design 2nd Edition by M. Morris Mano,Michael D. Ciletti
Digital Design 3rd Edition by M. Morris Mano,Michael D. Ciletti
Digital Design 4th edition Morris Mano
Digital Design-Principles and Practices 3rd Edition by John F. Wakerly [selected problems]
Digital Fundamentals 9th edition by Thomas L. Floyd
Digital Image Processing 2nd edition by Rafael C. Gonzalez
Digital Integrated Circuits 2nd edition by Rabaey
Digital Integrated Circuits by Thomas A. DeMassa & Zack Ciccone
Digital Logic And Computer Design , 4th ed , by M.Morris Mano & MICHAEL D. CILETTI
Digital Logic Design 2nd edition by M. Morris Mano
Digital Signal Processing - A Modern Introduction, 1st Edition Cengage learning Ashok Ambardar
Digital Signal Processing ;  A Computer-Based Approach 1st edition By sanjit K. Mitra
Digital Signal Processing 2nd Edition by Mitra
Digital Signal Processing 3nd Edition by Mitra
Digital Signal Processing 4th edition by John G. Proakis and Dimitri s G. Manolakis
Digital Signal Processing A Computer-Based Approach , 2nd ed , by Sanjit Mitra
Digital Signal Processing by Thomas J. Cavicchi
Digital signal processing proakis manolakis
Digital Signal Processing Signals, Systems, and Filters Andreas Antoniou
Digital Signal Processing Using Matlab 2nd edition by Vinay K Ingle Proakis
Digital Systems-Principles and Applications 10th Ed. by Ronald Tocci, Neal S. Widmer & Gregory L. Moss
Discrete Mathematics with Applications Third Edition By Susanna S. Epp
Discrete Mathematics, 6th ed , by richard Johnsonbaugh
Discrete Time Digital Signal Processing , 2nd ed 1999 , by Prentice Hall
Discrete Time Signal Processing 2nd Edition, by Alan V. Oppenheim
Discrete time signal processing 3rd edition by Oppenheim
Econometric Analysis , 5 th ed 2001 , by William H. Greene
Econometric Analysis of Cross Section and Panel Data , 2003 , by Wooldridge
Econometrics , 2nd ed , by Badi H. Baltagi
Economics Advanced Macroeconomics , 3 rd edition 2006 , by Romer  McGraw Hill
Electric Circuits 7th edition by Nilsson
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Electric circuits 9th Edition By Nilsson Riedel
Electric Machinery 6th Edition by Fitzgerald Kingsley
Electric Machinery and Power System Fundamentals 1st edition by Stephen Chapman
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Electric Machinery Fundamentals 4th edition by Stephen J. Chapman
Electric Machines Analysis and Design Applying MATLAB by Jim Cathey
Electrical Engineering Electric Machinery , 6th ed Fitzgerald & Kingsley & Uman
Electrical Engineering Principles and Applications 3rd edition by Allan R. Hambley
Electrical Machines, Drives and Power Systems 6th edition By Theodore Wildi
Electromagnetic Fields and Energy 1st Ed. by Haus and Melcher
Electromagnetics for Engineers by Ulaby
Electromagnetism Major American Universities Ph.D. Qualifying Questions and Solutions by Lim Yung-Kuo
Electromechanical Dynamics I , by Herbert H. Woodson & James R. Melcher
Electronic Circuit Analysis and Design 2nd edition by Donald A. Neamen
Electronic devices - electron flow version 4th edition by thomas l.floyd
Electronic Devices and Circuit Theory , 10 th ed , by Robert L. Boylestad & Louis Nashelsky
Electronic Devices and Circuit Theory 8th Ed.  with Lab Solutions, and Test Item File by Robert Boylestad
Electronic Devices-6th Edition by Thomas L. Floyd
Electronic Physics by Strabman
Elementary Differential Equations , 8th ed , by Werner Kohler & Lee Johnson
Elementary Differential Equations 8th edition by Boyce
Elementary Differential Equations And Boundary Value Problems, 7Th Edition by Boyce And Diprima
Elementary Differential Equations with Boundary Value Problems , 4th ed , by C.H. Edwards & David E. Penney
Elementary Linear Algebra With Applications ,  10 th ed , by Anton
Elementary Linear Algebra with Applications 9th by Howard Anton, Chris Rorres
Elementary Mechanics and Thermodynamics by Jhon W. Norbury
Elementary Number Theory and Its Applications, 5th edition by Kenneth H. Rosen
Elementary Number Theory and Its Applications, 6th Ed. By Kenneth H. Rosen
Elementary Principles of Chemical Processes 3rd edition by Richard M. Felder,Ronald W. Rousseau
Elements of Chemical Reaction Engineering 4th Edition by Brian Vicente, Max Nori, H. Scott Fogler
Elements of Chemical Reaction Engineering, 3rd Edition by H. Scott Fogler
Elements of electromagnetics 2nd edition by sadiku
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Elements Of Information Theory , 1992 ,By Thomas Cover, Joy A. Thomas
Elements of Power System Analysis 4th edition by William D. Stevenson
Embedded Microcomputer Systems Real Time Interfacing 2nd Edition by Jonathan W. Valvano
Engineering Circuit Analysis 6th edition by Hayt
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Engineering Economy 7th Edition Solution Manual By Leland Blank and Anthony Tarquin
Engineering Electromagnetics - 7th Ed. - Hayt
Engineering Electromagnetics 2d Edition by Nathan Ida
Engineering Electromagnetics 6th Edition by William H. Hayt Jr. and Hohn A. Buck
Engineering Fluid Mechanics , 8th Ed , by Donald Elger & Clayton Crowe
Engineering Fluid Mechanics 7th edition by Clayton T. Crowe, Donald F. Elger & John A. Roberson
Engineering Fundamentals of Machine Component Design , 3rd ed , by Juvinall & Marshek
Engineering Mathematics 4th edition by John Bird
Engineering Mathematics 4th Edition by NEWNES
Engineering Mechanic STATICS 10th Ed. R.C. Hibbeler
Engineering Mechanics - Dynamics 2 Edition by Riley and Sturges
Engineering Mechanics - Dynamics 11th edition by R. C. Hibbeler
Engineering Mechanics - STATICS 4th E - Bedford and Fowler
Engineering mechanics - statics 10th edition by R. C. Hibbeler
Engineering mechanics Dynamics 4th Ed. by Bedford and Fowler
Engineering Mechanics Dynamics 5th J.L Meriam
Engineering Mechanics Dynamics, 6th ed, by J. L. MERIAM
Engineering Mechanics Statics , 5th ed , by Anthony Bedford & Wallace T. Fowler
Engineering Mechanics Statics 6th edition by J.L Meriam
Engineering Mechanics Statics 11th Edition By R.C.Hibbeler
Engineering Statistics , 4 th ed , by Douglas C. Montgomery & George C. Runger & Norma F. Hubele
engineering vibration , 3rd ed , by daniel j inman
Feedback Control of Dynamic Systems 4th edition by G. F. Franklin, J. D. Powell, A. Emami
Feedback control of dynamic systems 6th edition by G. F. Franklin, J. D. Powell, A. Emami
Field and Wave Electromagnetics 2nd Edition by Wesley Cheng
Field and Wave Electromagnetics International Edition by David K
Financial Accounting (V.1 & V.2 & V.3) , 2008 edition , by Valix and Peralta
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Fluid Mechanics 1st edition by CENGEL
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Fluid Mechanics With Engineering Applications 10th edition by E. John Finnemore, Joseph B Franzini
Fracture mechanics fundamentals and applications 2nd edition by Northam Anderson
Fundamental Methods of Mathematical Economics , 4 th ed , by Alph C. chaing & Kevin wainwright
Fundamental of Electric Circuits 3rd editoin by C. K. Alexander M. N. O. Sadiku
Fundamental of engineering electromagnetics by David Cheng
Fundamental of Financial Management , 12 ed , by James C. Van Horne & John M. Wachowicz JR
Fundamentals of aerodynamics , 2nd ed , by John D. Anderson Jr
Fundamentals of Digital Logic with Verilog Design 1st edition by S. Brown Z. Vranesic
Fundamentals of Digital Logic with VHDL Design, 1st edt. by S. Brown, Z. Vranesic
Fundamentals of Digital Signal Processing Using MATLAB , 2nd ed 2012 , by Robert A. Schilling & Cengage Learning
Fundamentals of Electric Circuits 2nd edition by C. K. Alexander M. N. O. Sadiku
Fundamentals of Electric Circuits, 3rd edition by C. K. Alexander M. N. O. Sadiku
Fundamentals of Engineering Economics , 2nd ed , by Park
Fundamentals of engineering thermodynamics by m. j. moran  h. n. shapiro
Fundamentals Of Fluid Mechanics , 6th ed , by Munson
Fundamentals of Fluid Mechanics , 6th ed 2009 , by Munson
Fundamentals of Fluid mechanics 4th edition by Munson
Fundamentals of Fluid Mechanics Student Solutions Manual, 3rd Edition [Student solution manual]
Fundamentals of Heat and Mass Transfer 4th edition  by Incropera & Dewitt
Fundamentals of logic design 5th edition by  Charles Roth
Fundamentals of Machine Component Design - 3rd edition by Robert C. Juvinall and Kurt M. Marshek
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Fundamentals of Physics 7th edition by Halliday, Resnick and Walker
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Fundamentals of Physics extended , 9 th ed , by Halliday & resnick
Fundamentals of Power Electronics 2nd edition by R.W. Erickson
Fundamentals of Power Semiconductor Devices 1st Ed. by B. Jayant Baliga
Fundamentals Of Probability With Stochastic Processes , 3nd ed 2005 , by Prentice H. & SAEED GHAHRAMANI
fundamentals of quantum mechanics for solid state electronics and optics , 2005 edition , by C.L Tang
Fundamentals of Signals and systems using web and matlab third edition by Edward W. Kamen, Bonnie S Heck
Fundamentals of Solid-State Electronics by Chih-Tang Sah
Fundamentals of Thermal Fluid Sciences by Yunus A. Cengel, Robert H. Turner, Yunus Cengel, Robert Turner
Fundamentals of Thermodynamics 6th edition by sontag
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Fundamentals of Wireless Communication by Tse and Viswanath
Game Theory , An Introduction , 2013 , by Steve Tadelis
Geometry A High School Course , 1994 edition , by S. Lang & G.Murrow
Heat Transfer A Practical Approach 2nd edition by Yunus A. Cengel, Yunus Cengel
How English Works A Grammar Handbook with Readings Instructor's Manual by Ann Raimes
Intermediate Accounting , 2nd ed 2010 , by EmpLeo RobLes
Intermediate Accounting , 14th ed
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Introduction To Algorithms , 2 nd ed , by Thomas H. Cormen & Charles E. Leiserson & Ronald L. Rivest & Clifford Stein
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Introduction to chemical engineering thermodynamics 6th edition by j. m. smith
Introduction to Communication Systems 3rd Edition by Stremler
Introduction to Computing and Programming with JAVA-A Multimedia Approach 1st Edition by Mark Guzdial and Barbara Ericson
Introduction to Data Mining , 2006 , by Pang Ning Tan , Michael Steinbach , Vipin Kumar
Introduction to Econometrics , 2003 edition , by James H. Stock , Mark W. Watson
Introduction to electric circuits 6th edition by Dorf Svaboda
Introduction to Electric Circuits 7th edition by Richard C. Dorf & James A. Svoboda
Introduction to elementary particles by D.Griffiths
Introduction to Eletrodynamics  3rd ed By David J. Griffiths
Introduction to Environmental Engineering and Science 3rd Edition
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Introduction to Flight , 6th ed , by John D.Anderson Jr
Introduction to fluid mechanics 5th edition by fox and mcdonald
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Introduction to Graph Theory , 2nd ed ,by Douglas B. West
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Introduction to Linear Algebra 3rd Edition By Gilbert Strang
Introduction to Linear Programming 1st Edition by L. N. Vaserstein [student solution manual]
Introduction to modern statistical mechanics , by David Wu & David Chandler
Introduction to Probability by Dimitri P. Bertsekas
Introduction to Quantum Mechanics (1995) by David J. Griffiths
Introduction to Quantum Mechanics , 2nd Ed.2005 , by David Jeffery Griffiths
Introduction to Queueing Theory , 2nd ed , by Robert  B. Cooper & Borge Tilt
Introduction to Solid State Physics by Charles Kittel
Introduction to VLSI Circuits and Systems John P Uyemura
Introduction to Wireless Systems by P.M. Shankar
IP Telephony Solution guide
IT Networking Labs by Tom Cavaiani
Java How to Program, 5th Edition By Harvey M. Deitel, Paul J. Deitel
Journey into Mathematics An Introduction to Proofs (Book and solution manual) by Joseph J. Rotman
KC's Problems and Solutions for Microelectronic Circuits, Fourth Edition by Adel S. Sedra, K. C. Smith, Kenneth C. Smith
Labview for engineers 1st edition by R.W. Larsen
Linear Algebra a modern introduction Second Edition by David Poole
Linear Algebra and Its Applications by David C. Lay
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Linear Algebra Done Right, 2nd ed , by Sheldon Axler (ISBN 0387982590)(1997)
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Starting Out with Java 5 Lab Manual to Accompany Starting out with Java 5 by Diane Christen
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Statistical Inference , 2 nd ed 2001 , by George Casella & Roger L. Berger & Damaris Santana
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Student Solution Manual for Essential Mathematical Methods for the Physical Sciences by K. F. Riley, M. P. Hobson
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The ARRL Instructor's Manual for Technician and General License Courses By American Radio Relay League
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From marko at pacujo.net  Mon Mar 24 03:47:44 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 24 Mar 2014 09:47:44 +0200
Subject: loop
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
 <mailman.8426.1395622335.18130.python-list@python.org>
Message-ID: <87fvm811i7.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Mon, Mar 24, 2014 at 11:35 AM,  <pabloeruggeri at gmail.com> wrote:
>> I'm trying to create a for loop that starts at 100 and goes to 10Mllion.
>
> That sounds like a logarithmic scale.

How about:

    for i in [ 100, 1000, 10000, 100000, 1000000, 10000000, 100000000 ]:
        ...


Marko


From ian.g.kelly at gmail.com  Mon Mar 24 05:03:12 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 24 Mar 2014 03:03:12 -0600
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lgoh7j$otg$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
Message-ID: <CALwzid=-BOAa0yz5bsi6V5N0Wi8EUp0KXCjQcv6mrjxVd78nzA@mail.gmail.com>

On Mar 23, 2014 11:56 PM, "Mark H Harris" <harrismh777 at gmail.com> wrote:
>
> On 3/22/14 4:46 AM, Steven D'Aprano wrote:
>>
>> On Fri, 21 Mar 2014 23:51:38 -0500, Mark H Harris wrote:
>>
>>> Lambda is a problem, if only because it causes confusion. What's the
>>> problem?  Glad you asked. The constructs DO NOT work the way most people
>>> would expect them to, having limited knowledge of python!
>
>
>    One of the best links for understanding what is wrong with lambda is
here, from Guido, (by the way I agree totally with his assessment, there is
no point really in writing it out again):
>
>   http://www.artima.com/weblogs/viewpost.jsp?thread=98196

That post doesn't point out anything "wrong" with lambda. The argument
boils down to: 1) map and filter are not useful because we have
comprehensions; 2) reduce is confusing; 3) if we remove those then lambda
is not useful either.

> Lambda is a problem of confusion for scientists and other mathematicians
(amateur and otherwise) who may be confused because python's lambda does
not do precisely what they might expect from other functional programming
languages, nor does it match precisely with the lambda calculus. Its also
confusing to sophisticated users of all stripes who may not be aware of
"lambda" at all.

The difference does not really lie in the lambda construct per se but in
the binding style of closures. Functional languages tend to go one way
here; imperative languages tend to go the other. Python being primarily an
imperative language follows the imperative model. Anonymous functions in
Python work the same way in this regard as anonymous functions in Lua or
ECMAScript or Go -- those other languages merely avoid the cardinal sin of
defining their anonymous functions using the keyword "lambda". The result
may be more surprising to users accustomed to functional languages, but I
claim that it is *less* surprising to users of other imperative languages.

>> Python is not a pure functional language, but you can write functional
>> code in it. If you want a pure functional language, you know where to
>> find one.
>
>
>    Yes, that's obvious; but you're missing the point. Python is not a
functional language, and implying that it can be used as one is misleading
at best (maybe a lie at worst) just because it has a construct for
generating a dynamic anonymous function.

Oh, give me a break. If you find that you can't write functional code in
Python just because closure bindings are slightly inconvenient, then you
can't be trying very hard.

>    Well, number one, I'm not demanding anything. Number two, everyone who
uses Haskell (for whatever reason) knows well from the start that its a
pure functional programming language. That is the advertisement, and that
is the expectation. No one expects anything different.

And I would hope that anybody who uses Python is likewise aware from the
stay that it *isn't* a purely functional language.

>> Python could deprecate many things. It would make Python a worse
language.
>
>
>    How so?  Read Guido's argument above. Another way to answer this
question is that I have been programming with Python for almost a decade
and I've not used lambda. In fact, I have gone out of my way to NOT use
lambda because I am fully aware that the BDFL hates it.

If lambda were going to be deprecated and removed then it already would
have happened in Python 3, because Guido tried to do precisely that. I'm
not sure what the reasons were for keeping it in the end (according to PEP
3099 it was because nobody suggested a suitable replacement), but if he
couldn't get rid of it then, he never will.
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From breamoreboy at yahoo.co.uk  Mon Mar 24 05:40:51 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 24 Mar 2014 09:40:51 +0000
Subject: loop
In-Reply-To: <87fvm811i7.fsf@elektro.pacujo.net>
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
 <mailman.8426.1395622335.18130.python-list@python.org>
 <87fvm811i7.fsf@elektro.pacujo.net>
Message-ID: <lgouis$er3$1@ger.gmane.org>

On 24/03/2014 07:47, Marko Rauhamaa wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> On Mon, Mar 24, 2014 at 11:35 AM,  <pabloeruggeri at gmail.com> wrote:
>>> I'm trying to create a for loop that starts at 100 and goes to 10Mllion.
>>
>> That sounds like a logarithmic scale.
>
> How about:
>
>      for i in [ 100, 1000, 10000, 100000, 1000000, 10000000, 100000000 ]:
>          ...

Why the overhead of creating a list when you could use a tuple? :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From steve at pearwood.info  Mon Mar 24 05:49:35 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 24 Mar 2014 09:49:35 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
Message-ID: <532fffaf$0$29878$c3e8da3$5496439d@news.astraweb.com>

On Mon, 24 Mar 2014 00:52:52 -0500, Mark H Harris wrote:

> On 3/22/14 4:46 AM, Steven D'Aprano wrote:
>> On Fri, 21 Mar 2014 23:51:38 -0500, Mark H Harris wrote:
>>
>>> Lambda is a problem, if only because it causes confusion. What's the
>>> problem?  Glad you asked. The constructs DO NOT work the way most
>>> people would expect them to, having limited knowledge of python!
> 
>     One of the best links for understanding what is wrong with lambda is
> here, from Guido, (by the way I agree totally with his assessment, there
> is no point really in writing it out again):
> 
>    http://www.artima.com/weblogs/viewpost.jsp?thread=98196

It's only one paragraph. Here it is:

    Why drop lambda? Most Python users are unfamiliar with Lisp or
    Scheme, so the name is confusing; also, there is a widespread
    misunderstanding that lambda can do things that a nested function
    can't -- I still recall Laura Creighton's Aha!-erlebnis after I
    showed her there was no difference! Even with a better name, I think
    having the two choices side-by-side just requires programmers to
    think about making a choice that's irrelevant for their program; not
    having the choice streamlines the thought process. Also, once map(),
    filter() and reduce() are gone, there aren't a whole lot of places
    where you really need to write very short local functions; Tkinter
    callbacks come to mind, but I find that more often than not the
    callbacks should be methods of some state-carrying object anyway (the
    exception being toy programs). 


None of map(), filter() or reduce() are gone. reduce() has been pushed 
out into a module, but map() and filter() have actually been enhanced. 
Any suggestion that lambda is obsolete flounders on that fact.

There's no doubt that lambda is less-often useful than is the def 
statement. But not only is it still useful, but there is a continual 
stream of people asking for Python to make it *more useful* by allowing 
the body of a lambda to be a full block, not just a single statement. 
Guido has stated (although I cannot remember where, so cannot paste a 
link) that he accepts that in principle, so long as somebody comes up 
with acceptable syntax.

In Ruby, anonymous blocks are used *all the time*. Python is not Ruby, 
and never will be, but a lightweight way to generate anonymous functions 
in expressions is one difference between a modern, powerful language, and 
an archaic or toy under-powered language. I'm too lazy to do this the 
right way, but there are at least 99 mentions of "lambda" in the 3.3 
standard library:

steve at runes:/usr/local/lib/python3.3$ grep lambda *.py | wc -l 
99


It's used in calendar, cgitb, configparser, difflib, decimal, functools, 
inspect, os, pydoc and others. Python is a programming language aimed at 
programmers, not a toy. It should include tools that programmers use, 
like threads, closures, first-class functions. And lambda.


>> Why is that a problem? Would you consider it a problem that people who
>> don't understand BASIC can't understand BASIC? ("I don't get the
>> difference between GOTO and GOSUB. {snip}
>>
>> The problem is ignorance, not the calculator, and not lambda.
> 
>     You're argument, based on analogy, is also a red herring, as well a
> straw man. 

Please stop misusing "straw man". It has a specific meaning:

https://yourlogicalfallacyis.com/strawman


> Lambda is a problem of confusion for scientists and other
> mathematicians (amateur and otherwise) who may be confused because
> python's lambda does not do precisely what they might expect from other
> functional programming languages, nor does it match precisely with the
> lambda calculus. 

Yes, you've already said that. And my response remains the same: users of 
a language should be expected to learn the language, at least to the 
point that they can "get by". One doesn't need ten thousand hours 
experience and to be an expert. But nor should the confusion of somebody 
who doesn't know the language count for much.

Python's ints don't work exactly the same as ints do in some other 
languages, nor do Python's strings, nor is Python's object model 
precisely the same as that of some other languages. I think that it would 
be a ridiculous idea to discard int, str and the entire object system 
just because some people are surprised that Python doesn't behave exactly 
like some other language. I don't think lambda is any different.

The same argument applies to *any other language*. Ocaml is not precisely 
the same as Haskell, Java not precisely the same as C++, Ruby is not 
precisely the same as Javascript. Should Ruby discard their anonymous 
blocks because they don't work "precisely" the same as Haskell? Or 
perhaps Haskell should throw the towel in because it doesn't behave 
"precisely" the same as Ruby? 

Of course not -- new languages come into existence precisely so that they 
will be different from what is already there. Who is to say that there 
aren't people who like Python's lambda *because* it is different from the 
anonymous functions in other languages? Or because it is less abstract 
than the lambda calculus?

Other languages -- not even Lisp -- don't get to be the sole decider as 
to what counts as an anonymous function. Python's lambda may be limited, 
but it is a perfectly fine lambda for what it is intended to do.


> Its also confusing to sophisticated users of all
> stripes who may not be aware of "lambda" at all.

If they're not aware of lambda, how are they confused by it?


>> You've told us that "most people" (which people? dentists? lawyers?
>> illiterate tribesmen from the Amazon? professional programmers?) are
>> surprised by lamba's behaviour, but you haven't actually told us what
>> behaviour is surprising, or what "most people" expect lambda to do.
>> Perhaps you ought to?
> 
>     I love your rhetoric, actually, but red herrings all . . .

No, not really. I don't understand who your intended audience for Python 
is. If I were to try to guess, I suspect that you want to dumb Python 
down until it is like Dartmouth BASIC circa 1980 except without the line 
numbers and with a slightly different syntax. Perhaps I'm wrong, I 
certainly hope I'm wrong, but that's the impression I got from your 
comments on the python-ideas list. 

Python is a programming language. People who program in Python are 
programmers. It doesn't matter whether they are school children, or 
scientists, or farmhands, once they start writing programs, they are 
programming, which makes them a programmer. They might not be paid for 
it, but they are still programmers. Who should be using Python, if not 
programmers?


>     Here is a link that advocates lambda (map, filter, and reduce) as a
> very powerful construct for doing various things:  I agree:
> 
> http://www.secnetix.de/olli/Python/lambda_functions.hawk
> 
>     Its a great link, but the important sentence for this discussion is
> this unique quote, about "lambda,"
> 
>  >"This is not exactly the same as lambda in functional
>> programming languages, but it is a very powerful concept . . ."
> 
>     People who understand lambda from functional languages must hassle
> with the fact that lambda is different in python, and people who do not
> understand functional programming languages (nor the lambda calculus)
> are confused by the syntax, also just what it does.

You want to remove lambda because it causes confusion. Okay, for the sake 
of the argument I will agree that lambda is confusing. Do you know what 
else is confusing?

Threading is confusing. So is multiprocessing. So are databases. Unicode 
is confusing. First-class functions are confusing. Recursion is 
confusing. Closures are confusing. List comprehensions are confusing. 
What the hell are trampolines? I'm certainly confused by them.

If we remove lambda because it is confusing, shouldn't we also remove all 
these other confusing things? Where shall we stop?

Should we stop only when Python is a confusion-free, utterly useless toy 
language? I don't think so. Or should we stop *before* going down that 
path? You want to single out lambda. I don't think we should.


>> Python is not a pure functional language, but you can write functional
>> code in it. If you want a pure functional language, you know where to
>> find one.
> 
>     Yes, that's obvious; but you're missing the point. Python is not a
> functional language, and implying that it can be used as one is
> misleading at best (maybe a lie at worst) just because it has a
> construct for generating a dynamic anonymous function.

I didn't say that Python can be used as a functional language. I said you 
can write functional code in Python. And that is so obviously true that I 
cannot believe that you are disputing it.

Functions are first-class values. You can pass them around as arguments 
to other functions. You can wrap them to make closures, or compose them. 
You can return functions from other functions. You can, if you wish, 
eschew holding state and write pure functions with no side-effects and no 
state. You can even eschew local variables (well, mostly) inside your 
functions and do (nearly) everything by composing other functions. You 
can write pipelines of iterators, generators or co-routines.

It may be hard to write an *entire* application using nothing but 
functional style in Python, but using functional style throughout the 
application is so easy and simple that most people don't even realise 
that they are writing in a functional style when they do so.


>> (I wonder whether, say, Haskell has the people coming along and
>> demanding that it should become more like Python?)
> 
>     Another straw man.
> 
>     Well, number one, I'm not demanding anything. Number two, everyone
> who uses Haskell (for whatever reason) knows well from the start that
> its a pure functional programming language. That is the advertisement,
> and that is the expectation. No one expects anything different.

And everyone who uses Python ought to know that Python is not. That is 
the advertisement, and that ought to be the expectation.

Anonymous functions are not the sole preserve of purely functional 
languages, any more than objects are the sole preserve of purely OOP 
languages.


>>> I can see uses for python's lambda.  But, honestly, I think python
>>> could deprecate its use and in five years just remove it from the
>>> language; along with filter, map, and reduce !
>>
>> Python could deprecate many things. It would make Python a worse
>> language.
> 
>     How so?  Read Guido's argument above. Another way to answer this
> question is that I have been programming with Python for almost a decade
> and I've not used lambda. In fact, I have gone out of my way to NOT use
> lambda because I am fully aware that the BDFL hates it.

In other words, you have had situations where you *could have* used 
lambda, perhaps even *should have* used lambda, but you intentionally 
went *out of your way* (i.e. made the job harder than it needed to be) to 
avoid it, just to slavishly ape the BDFL.

Thank you for just proving my point for me. Your code would have been 
better, or at least easier, with lambda. Removing it would make the 
language worse, not better.


> Reduce is no
> longer in the standard library (although you can import it) 

You mean it is no longer in the builtin namespace. It is still in the 
standard library.


> and there
> are equally good ways to do what lambda was designed for without the
> hassle nor confusion.

Incorrect. lambda was designed to allow you to create anonymous functions 
in an expression, not as a statement. There is *no other way* to do that 
in Python. Even if you come up with some weird hack involving exec or 
FunctionType and code objects, it won't be *equally good*. It will be a 
broken, third-rate imitation of lambda.


>> By the way, are you aware that lambda is *identical* to def except for
>> three things?
>>
>> - lambda is an expression, not a statement like def;
>>
>> - the body of a function created with lambda is limited to a
>>    single expression, not a block;
>>
>> - the function object created with lambda has a generic name.
> 
>     Absolutely, thank you for pointing those out !  You forgot that
> lambdas can be used in expressions while def functions may not... 

Umm, read my list again. It's the first item.


> but
> you really have proved my point.  There is so little difference between
> the two that (for the sake of clarity and reducing confusion) it might
> be good to just remove the lambda thing altogether.  Just say'in.

The *number* of differences may be small, but the *consequences* of those 
differences are enormous.


>> So unless the surprising behaviour about lambda that you're about to
>> tell us about relates to one of those three things, I *guarantee* that
>> functions created with def have the same surprising behaviour.
> 
>     No, the surprising behavior is that python lambda does not work
> exactly the way that lambda works in functional programming languages

Then neither does def.

Would you like to discard def as well? No? Why not?


> (see the two links provided) the confusion it creates for "normal" users
> does not warrant its inclusion in the language.
> 
>     Having said that, I must admit that I've "played" with lambda
> extensively and find it interesting from a comp sci standpoint, but,
> again, for normal users I don't think there is a really good value add
> for having it in the language.




-- 
Steven


From shishirk at gmail.com  Mon Mar 24 05:15:17 2014
From: shishirk at gmail.com (Shishir)
Date: Mon, 24 Mar 2014 14:45:17 +0530
Subject: Asyncio (or something better) for control of a vacuum
 system/components.
Message-ID: <CAB4DN0U=4VBTow9cXgdotqfnrkvcx=Hr2UprM=Hup1W+JzibPQ@mail.gmail.com>

Dear All,

I apologise in advance a) if this is not the proper list for asking the
question, b) the length of the post.

I am writing a software to control and monitor a vacuum
furnace+attachments. It has a few mass flow controllers, a butterfly valve,
a labjack unit for analog/digital outputs etc. They use RS485, RS232 and
USB to communicate with the computer and follow special protocols for
commands and response. The response time to execute commands can be from 5
ms to 1 s.

To achieve this, I thought of a server which reads commands on a network
connections, parses the command and calls methods of appropriate device
classes, which then use the corresponding channel protocol to execute the
command. The response provided by the devices (flow controllers, valve) is
sent back on the network connection.

As there can be multiple clients (e.g. for monitoring from several
computers), and some commands can take long, the server should not block
when getting a command executed.

I wanted to use asyncio to achieve this non-blocking behaviour, i.e. when
the server calls the method of device classes, a callback is installed and
the method returns immediately. When the response is available from the
device, the callback writes the response to the client's connection.

Some (pseudo)code:

class server(Protocol):
    def connection_made(self, transport): self.transport = transport
    def data_received(self, data):
        device, command, args = parse(data)
        result = yield from device.command(args)
        self.transport.write(result)

class device1():
    self.channel = rs232()
    @asyncio.coroutine
    def command1(args):
        r = self.execute(self.channel, 'Cmd1', args) # this can take a while
        return r

# ++ get_event_loop code for running the server forever

This doesn't work as I expected. For example, I expected that when command1
is awaiting response from the device, the server can receive another
command2 on the same network connection, and get that executed (say on
another device). If the response of this command2 is available earlier, it
will be written to the network connection. Instead, the data_received call
for first command doesn't return till the command1 is completed. If the
execute() call is replaced by asyncio.sleep(r) it works as I expect.

The problem is that self.execute() blocks and the asyncio framework has no
way to know how to reschedule it or bypass it. This can be avoided if I
depended on I/O from a file descriptor, on which I can apply
poll()/select(). But the channel handler that I have is more generic
(rs232() in code above).

My question then is: is there a good way to handle the situation?

I would like to have following architecture:

A server sits on the computer which is connected to the devices via
channels (rs232, rs485, usb etc.). A client initiates a network connection
to the server and starts sending commands which are numbered. Server asks
the device classes for a response of execution of these commands on the
devices. The responses it receives (and dispatches to the client) from
device classes are not in same sequence, but that doesn't matter as they
are numbered by the client. There can be several clients. I also assume
that execution of each command on the devices is atomic, i.e. when the
device class connects to the device on later's channel, the channel is not
relinquished till the device provides a response. To achieve this, the
device classes obtain a lock on the channel they need before talking to the
device (and release it after they are done).


I have looked around the web but couldn't find an easy+flexible framework
to do what I have outlined here. Our lab is using a control panel written
in labview, which I believe does things sequentially (i.e. by blocking). It
works alright, but error handling is poor (crashes on errors and resets the
furnace state on a restart!). It is also done in Labview, is not portable
or can be addressed over network.


I have written/tested python code to control the following if anyone is
interested (will put up on bitbucket.org once I am done with the above
server):
T3Bi throttle valve controller from MKS (RS232 based)
GF40 MFCs from Brooks Instruments (RS485 based)
CMC & CMX gauges from Brooks Instruments (RS485, but currently controlled
by T3Bi)
1179A MFCs from MKS (which is controlled via analog output from a LabJack
U6)
SMC pneumatic switches (which are controlled via digital ports on LabJack
U6 + PS12VDC).
The LabJack parts use labjackpython library.

Thanks a lot for reading,
sid.
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From breamoreboy at yahoo.co.uk  Mon Mar 24 05:58:58 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 24 Mar 2014 09:58:58 +0000
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <lgoh7j$otg$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
Message-ID: <lgovks$3pi$1@ger.gmane.org>

On 24/03/2014 05:52, Mark H Harris wrote:
>
>     How so?  Read Guido's argument above. Another way to answer this
> question is that I have been programming with Python for almost a decade
> and I've not used lambda. In fact, I have gone out of my way to NOT use
> lambda because I am fully aware that the BDFL hates it. Reduce is no
> longer in the standard library (although you can import it) and there
> are equally good ways to do what lambda was designed for without the
> hassle nor confusion.
>

Where do you get reduce from if it's not in the standard library?  As 
for lambda I've no real interest in it, other than when copying examples 
where it's used to (say) provide a key function.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From marko at pacujo.net  Mon Mar 24 05:55:24 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 24 Mar 2014 11:55:24 +0200
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
Message-ID: <87bnwv2a5v.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> If lambda were going to be deprecated and removed then it already
> would have happened in Python 3, because Guido tried to do precisely
> that. I'm not sure what the reasons were for keeping it in the end
> (according to PEP 3099 it was because nobody suggested a suitable
> replacement), but if he couldn't get rid of it then, he never will.

You never *need* (Python's) lambda for anything. Inner functions are
more capable and almost always more readable. It doesn't hurt to have
lambda, but I don't find any use for it, either.


Marko


From marko at pacujo.net  Mon Mar 24 06:04:32 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 24 Mar 2014 12:04:32 +0200
Subject: loop
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
 <mailman.8426.1395622335.18130.python-list@python.org>
 <87fvm811i7.fsf@elektro.pacujo.net>
 <mailman.8441.1395654073.18130.python-list@python.org>
Message-ID: <877g7j29qn.fsf@elektro.pacujo.net>

Mark Lawrence <breamoreboy at yahoo.co.uk>:

> On 24/03/2014 07:47, Marko Rauhamaa wrote:
>>      for i in [ 100, 1000, 10000, 100000, 1000000, 10000000, 100000000 ]:
>
> Why the overhead of creating a list when you could use a tuple? :)

Once in college, we were given assembly programming assignments. The
textbook defined an imagined 18-bit CPU and an instruction set.

A fellow student was given the task to write a subroutine that
calculates the factorial of the argument. He went through the trouble of
creating a loop with multiplication etc. I argued (in vain) that his
solution is "wrong" from all angles; he should have implemented his
subroutine with a simple lookup table since 18 bits can only take a
handful of input values (0 through 8).


Marko


From nispray at gmail.com  Mon Mar 24 06:20:55 2014
From: nispray at gmail.com (Wesley)
Date: Mon, 24 Mar 2014 03:20:55 -0700 (PDT)
Subject: gdb python how to output integer for examine memory
Message-ID: <e1e8c3a2-5d8d-4aae-9a5d-82af79be8c4c@googlegroups.com>

Hi all,
  I am trying to use gdb debug python script.
I am using gdb7.7 and python2.7.6, here is my simple test script: 
import time

def next(i):
    time.sleep(10)
    i = 1 - i

i = 1
while True:
    next(i)
When this script running, gdb attach to it, and here is snippet:

(gdb) py-bt
#5 Frame 0x201e130, for file test.py, line 6, in next (i=1)
Python Exception <type 'exceptions.IOError'> (2, '\xe6\xb2\xa1\xe6\x9c\x89\xe9\x82\xa3\xe4\xb8\xaa\xe6\x96\x87\xe4\xbb\xb6\xe6\x88\x96\xe7\x9b\xae\xe5\xbd\x95', 'test.py'): 
Error occurred in Python command: (2, '\xe6\xb2\xa1\xe6\x9c\x89\xe9\x82\xa3\xe4\xb8\xaa\xe6\x96\x87\xe4\xbb\xb6\xe6\x88\x96\xe7\x9b\xae\xe5\xbd\x95', 'test.py')
(gdb) frame 5
#5  0x00000000004d01a7 in PyEval_EvalFrameEx (f=Frame 0x201e130, for file test.py, line 6, in next (i=1), throwflag=0) at Python/ceval.c:2666
2666                x = call_function(&sp, oparg);
(gdb) py-locals
i = 1
(gdb) pyo i
No symbol "i" in current context.
(gdb) 
No symbol "i" in current context.
(gdb) p f->f_localsplus
$1 = {1}
(gdb) p f->f_localsplus[0]
$2 = 1
(gdb) p &(f->f_localsplus[0])
$3 = (PyObject **) 0x201e2b8
(gdb) x/d 0x201e2b8
0x201e2b8:      31304528
(gdb) p sizeof(f->f_localsplus[0])
$4 = 8
(gdb) x/dg 0x201e2b8
0x201e2b8:      31304528
(gdb) x/dw 0x201e2b8
0x201e2b8:      31304528
(gdb) 

So, the latter several commands, I wannted to check memory content, but , how to output integer 1?

Thanks.
Wesley


From marko at pacujo.net  Mon Mar 24 06:22:05 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 24 Mar 2014 12:22:05 +0200
Subject: Asyncio (or something better) for control of a vacuum
 system/components.
References: <mailman.8442.1395655124.18130.python-list@python.org>
Message-ID: <8738i728xe.fsf@elektro.pacujo.net>

Shishir <shishirk at gmail.com>:

> The problem is that self.execute() blocks and the asyncio framework
> has no way to know how to reschedule it or bypass it. This can be
> avoided if I depended on I/O from a file descriptor, on which I can
> apply poll()/select(). But the channel handler that I have is more
> generic (rs232() in code above).

Deep down asyncio depends on file descriptors. If your thingy is another
kind of object, it needs to go into its own process or thread.

> A server sits on the computer which is connected to the devices via
> channels (rs232, rs485, usb etc.). [...]

Sounds about right.

> I have looked around the web but couldn't find an easy+flexible
> framework to do what I have outlined here.

Asyncio + subprocess should be all you need for a framework. However, some
system programming *will* be required.


Marko


From sales09 at opclabs.com  Mon Mar 24 06:41:35 2014
From: sales09 at opclabs.com (sales09 at opclabs.com)
Date: Mon, 24 Mar 2014 03:41:35 -0700 (PDT)
Subject: Writing an OPC client with Python ?
In-Reply-To: <440880b4$0$13692$636a55ce@news.free.fr>
References: <440880b4$0$13692$636a55ce@news.free.fr>
Message-ID: <8366e1f6-fa3b-41e7-b8b4-64c027089310@googlegroups.com>


OPC Python Example: Get OPC data into Python

http://www.opclabs.com/products/quickopc/languages-and-tools/python


From sales09 at opclabs.com  Mon Mar 24 06:42:47 2014
From: sales09 at opclabs.com (sales09 at opclabs.com)
Date: Mon, 24 Mar 2014 03:42:47 -0700 (PDT)
Subject: Python OPC -wrapper for data collection, anyone seen it ?
In-Reply-To: <3C07501E.3040807@vip.fi>
References: <3C07501E.3040807@vip.fi>
Message-ID: <7df31139-56b4-4f94-aec6-41cb7f813d04@googlegroups.com>

What about (our) QuickOPC: http://www.opclabs.com/products/quickopc/languages-and-tools/python 


From sales09 at opclabs.com  Mon Mar 24 06:43:21 2014
From: sales09 at opclabs.com (sales09 at opclabs.com)
Date: Mon, 24 Mar 2014 03:43:21 -0700 (PDT)
Subject: OPC for Python ?? (Win32)
In-Reply-To: <8ngvvh$25tb@drn.newsguy.com>
References: <8ngvvh$25tb@drn.newsguy.com>
Message-ID: <09af5e27-44d9-4a20-9d3b-0c10e1e9bebe@googlegroups.com>

QuickOPC: Get OPC data into Python

http://www.opclabs.com/products/quickopc/languages-and-tools/python




From sales09 at opclabs.com  Mon Mar 24 06:43:56 2014
From: sales09 at opclabs.com (sales09 at opclabs.com)
Date: Mon, 24 Mar 2014 03:43:56 -0700 (PDT)
Subject: Python in Process Control?
In-Reply-To: <joztfie8fghq.fdfzxi3urxbg$.dlg@40tude.net>
References: <joztfie8fghq.fdfzxi3urxbg$.dlg@40tude.net>
Message-ID: <ad0b1d03-c515-4329-a3e5-1798653ad0d6@googlegroups.com>

Get OPC data into Python: 
http://www.opclabs.com/products/quickopc/languages-and-tools/python 


From rosuav at gmail.com  Mon Mar 24 06:58:29 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 21:58:29 +1100
Subject: loop
In-Reply-To: <877g7j29qn.fsf@elektro.pacujo.net>
References: <e2be2ed8-e2b8-427c-b826-e7240ecc5bdf@googlegroups.com>
 <mailman.8426.1395622335.18130.python-list@python.org>
 <87fvm811i7.fsf@elektro.pacujo.net>
 <mailman.8441.1395654073.18130.python-list@python.org>
 <877g7j29qn.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmoqNrqF20moOa_0uWhmoErq15xkEFzUWED8C-08bm_fGQ@mail.gmail.com>

On Mon, Mar 24, 2014 at 9:04 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Once in college, we were given assembly programming assignments. The
> textbook defined an imagined 18-bit CPU and an instruction set.
>
> A fellow student was given the task to write a subroutine that
> calculates the factorial of the argument. He went through the trouble of
> creating a loop with multiplication etc. I argued (in vain) that his
> solution is "wrong" from all angles; he should have implemented his
> subroutine with a simple lookup table since 18 bits can only take a
> handful of input values (0 through 8).

The task was "calculates". If the task was "returns", then the lookup
table would be correct. :)

ChrisA


From rosuav at gmail.com  Mon Mar 24 07:21:20 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 22:21:20 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <532fffaf$0$29878$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <532fffaf$0$29878$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmo5o=WVbq3ogNR429uJJSPtTaHMrjP08bQt3nT_qzZB8w@mail.gmail.com>

On Mon, Mar 24, 2014 at 8:49 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> I'm too lazy to do this the
> right way, but there are at least 99 mentions of "lambda" in the 3.3
> standard library:
>
> steve at runes:/usr/local/lib/python3.3$ grep lambda *.py | wc -l
> 99

I'm not too lazy to do it the right way, but I don't have 3.3 handy,
so I've done it on 3.4 instead. There are 77 instances of lambda nodes
in the files you list there - which are the ones that aren't in
packages. (Note that two instances of lambda on the same line would
count as one in Steven's figure, but as two in mine. Also, his counts
comments. Still, his way's a lot easier to calculate, and it's in the
right ball-park.) Including all subdirectories raises that figure to,
get this, 1230. That's actual uses of the lambda keyword as parsed by
Python. This does include the test suite, though. Removing all files
with "/test/" in the names cuts that figure to only 273. But that's
still two hundred and seventy-three places where the Python standard
library uses lambda - a respectable figure.

ChrisA


From jamiemitchell1604 at gmail.com  Mon Mar 24 07:32:31 2014
From: jamiemitchell1604 at gmail.com (Jamie Mitchell)
Date: Mon, 24 Mar 2014 04:32:31 -0700 (PDT)
Subject: Memory error
Message-ID: <d4489c2b-6650-45b6-bcb0-7a1b648192d2@googlegroups.com>

Hello all,

I'm afraid I am new to all this so bear with me...

I am looking to find the statistical significance between two large netCDF data sets.

Firstly I've loaded the two files into python:

swh=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/controlperiod/averages/swh_control_concat.nc', 'r')

swh_2050s=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/2050s/averages/swh_2050s_concat.nc', 'r')

I have then isolated the variables I want to perform the pearson correlation on:

hs=swh.variables['hs']

hs_2050s=swh_2050s.variables['hs']

Here is the metadata for those files:

print hs
<type 'netCDF4.Variable'>
int16 hs(time, latitude, longitude)
    standard_name: significant_height_of_wind_and_swell_waves
    long_name: significant_wave_height
    units: m
    add_offset: 0.0
    scale_factor: 0.002
    _FillValue: -32767
    missing_value: -32767
unlimited dimensions: time
current shape = (86400, 350, 227)

print hs_2050s
<type 'netCDF4.Variable'>
int16 hs(time, latitude, longitude)
    standard_name: significant_height_of_wind_and_swell_waves
    long_name: significant_wave_height
    units: m
    add_offset: 0.0
    scale_factor: 0.002
    _FillValue: -32767
    missing_value: -32767
unlimited dimensions: time
current shape = (86400, 350, 227)


Then to perform the pearsons correlation:

from scipy.stats.stats import pearsonr

pearsonr(hs,hs_2050s)

I then get a memory error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/sci/lib/python2.7/site-packages/scipy/stats/stats.py", line 2409, in pearsonr
    x = np.asarray(x)
  File "/usr/local/sci/lib/python2.7/site-packages/numpy/core/numeric.py", line 321, in asarray
    return array(a, dtype, copy=False, order=order)
MemoryError

This also happens when I try to create numpy arrays from the data.

Does anyone know how I can alleviate theses memory errors?

Cheers,

Jamie


From jamiemitchell1604 at gmail.com  Mon Mar 24 07:39:47 2014
From: jamiemitchell1604 at gmail.com (Jamie Mitchell)
Date: Mon, 24 Mar 2014 04:39:47 -0700 (PDT)
Subject: Memory error
In-Reply-To: <d4489c2b-6650-45b6-bcb0-7a1b648192d2@googlegroups.com>
References: <d4489c2b-6650-45b6-bcb0-7a1b648192d2@googlegroups.com>
Message-ID: <81019e01-c101-4025-af2a-bea0c193230d@googlegroups.com>

On Monday, March 24, 2014 11:32:31 AM UTC, Jamie Mitchell wrote:
> Hello all,
> 
> 
> 
> I'm afraid I am new to all this so bear with me...
> 
> 
> 
> I am looking to find the statistical significance between two large netCDF data sets.
> 
> 
> 
> Firstly I've loaded the two files into python:
> 
> 
> 
> swh=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/controlperiod/averages/swh_control_concat.nc', 'r')
> 
> 
> 
> swh_2050s=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/2050s/averages/swh_2050s_concat.nc', 'r')
> 
> 
> 
> I have then isolated the variables I want to perform the pearson correlation on:
> 
> 
> 
> hs=swh.variables['hs']
> 
> 
> 
> hs_2050s=swh_2050s.variables['hs']
> 
> 
> 
> Here is the metadata for those files:
> 
> 
> 
> print hs
> 
> <type 'netCDF4.Variable'>
> 
> int16 hs(time, latitude, longitude)
> 
>     standard_name: significant_height_of_wind_and_swell_waves
> 
>     long_name: significant_wave_height
> 
>     units: m
> 
>     add_offset: 0.0
> 
>     scale_factor: 0.002
> 
>     _FillValue: -32767
> 
>     missing_value: -32767
> 
> unlimited dimensions: time
> 
> current shape = (86400, 350, 227)
> 
> 
> 
> print hs_2050s
> 
> <type 'netCDF4.Variable'>
> 
> int16 hs(time, latitude, longitude)
> 
>     standard_name: significant_height_of_wind_and_swell_waves
> 
>     long_name: significant_wave_height
> 
>     units: m
> 
>     add_offset: 0.0
> 
>     scale_factor: 0.002
> 
>     _FillValue: -32767
> 
>     missing_value: -32767
> 
> unlimited dimensions: time
> 
> current shape = (86400, 350, 227)
> 
> 
> 
> 
> 
> Then to perform the pearsons correlation:
> 
> 
> 
> from scipy.stats.stats import pearsonr
> 
> 
> 
> pearsonr(hs,hs_2050s)
> 
> 
> 
> I then get a memory error:
> 
> 
> 
> Traceback (most recent call last):
> 
>   File "<stdin>", line 1, in <module>
> 
>   File "/usr/local/sci/lib/python2.7/site-packages/scipy/stats/stats.py", line 2409, in pearsonr
> 
>     x = np.asarray(x)
> 
>   File "/usr/local/sci/lib/python2.7/site-packages/numpy/core/numeric.py", line 321, in asarray
> 
>     return array(a, dtype, copy=False, order=order)
> 
> MemoryError
> 
> 
> 
> This also happens when I try to create numpy arrays from the data.
> 
> 
> 
> Does anyone know how I can alleviate theses memory errors?
> 
> 
> 
> Cheers,
> 
> 
> 
> Jamie

Just realised that obviously pearson correlation requires two 1D arrays and mine are 3D, silly mistake!


From rosuav at gmail.com  Mon Mar 24 07:49:38 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 22:49:38 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <87bnwv2a5v.fsf@elektro.pacujo.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmppnWa91zWDyqtsrCSgAD9i_hAGb9aHXCi5-QPftrmPNQ@mail.gmail.com>

On Mon, Mar 24, 2014 at 8:55 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Ian Kelly <ian.g.kelly at gmail.com>:
>
>> If lambda were going to be deprecated and removed then it already
>> would have happened in Python 3, because Guido tried to do precisely
>> that. I'm not sure what the reasons were for keeping it in the end
>> (according to PEP 3099 it was because nobody suggested a suitable
>> replacement), but if he couldn't get rid of it then, he never will.
>
> You never *need* (Python's) lambda for anything. Inner functions are
> more capable and almost always more readable. It doesn't hurt to have
> lambda, but I don't find any use for it, either.

They're often not more readable. A lot of people seem to equate
"verbose" with "readable", possibly by faulty extrapolation from
unreadably crunched code with one-letter variables and no line breaks.
But which of these is truly more readable?

squares = []
for n in range(30):
    squares.append(n * n)

squares = [n * n for n in range(30)]

Similarly, there are plenty of cases where a nameless function is MUCH
clearer than breaking it out into a separate def and then using the
name once. Do you name the function for what it does internally?

def get_oneth_element_index(item):
    return item[1].index
L.sort(key=get_oneth_element_index)

Or for how you're using it?

def keyfunc(item):
    return item[1].index
L.sort(key=keyfunc)

Or do you just shortcut the whole thing by inlining it?

L.sort(key=lambda item:item[1].index)

Hey look, that's weakref.py line 941 right there. (It happens to be
the alphabetically last use of lambda in the stdlib. Made a good
example, although it'd be more common to have a space after that
colon.)

ChrisA


From davea at davea.name  Mon Mar 24 08:22:59 2014
From: davea at davea.name (Dave Angel)
Date: Mon, 24 Mar 2014 08:22:59 -0400 (EDT)
Subject: gdb python how to output integer for examine memory
References: <e1e8c3a2-5d8d-4aae-9a5d-82af79be8c4c@googlegroups.com>
Message-ID: <lgp7pi$61b$1@ger.gmane.org>

 Wesley <nispray at gmail.com> Wrote in message:
> Hi all,
>   I am trying to use gdb debug python script.
> I am using gdb7.7 and python2.7.6, here is my simple test script: 
> import time
> 
> def next(i):
>     time.sleep(10)
>     i = 1 - i
> 
> i = 1
> while True:
>     next(i)
> When this script running, gdb attach to it, and here is snippet:
> 

I cannot help with gdb, but I can point out that you have two
 separate variables here. Decrement ing the local has no effect on
 the global value.

The preferred way is to return any values from the function that
 you want to use after it exits. 
def next(i):
     time.sleep(10)
     i = 1 - i
     return i

i = 1
while True:
    i =next(i)

Another possibility,  generally a bad idea,  is declaring i global
 in the function. 

-- 
DaveA



From mauro at gmail.com  Mon Mar 24 08:23:34 2014
From: mauro at gmail.com (mauro)
Date: Mon, 24 Mar 2014 12:23:34 GMT
Subject: Asyncio (or something better) for control of a vacuum
 system/components.
References: <mailman.8442.1395655124.18130.python-list@python.org>
Message-ID: <atVXu.28207$Th2.17542@tornado.fastwebnet.it>

Hav you considered the option of a SCADA solution? There are many 
commercials solutions but also a few open source options such us:
http://openscada.org/
http://pvbrowser.de/pvbrowser/index.php

You may also ask the vacuum system provider, they should be aware of 
SCADA solutions supporting their communication protocols


From marko at pacujo.net  Mon Mar 24 08:36:48 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 24 Mar 2014 14:36:48 +0200
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
Message-ID: <87r45rzsbj.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Similarly, there are plenty of cases where a nameless function is MUCH
> clearer than breaking it out into a separate def and then using the
> name once. Do you name the function for what it does internally?
>
> def get_oneth_element_index(item):
>     return item[1].index
> L.sort(key=get_oneth_element_index)
>
> Or for how you're using it?
>
> def keyfunc(item):
>     return item[1].index
> L.sort(key=keyfunc)
>
> Or do you just shortcut the whole thing by inlining it?
>
> L.sort(key=lambda item:item[1].index)

I still prefer the "def" variant. It even allows you to clarify the
meaning of the tuple slot by using a nicer name.


Marko


From rosuav at gmail.com  Mon Mar 24 08:53:12 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 24 Mar 2014 23:53:12 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <87r45rzsbj.fsf@elektro.pacujo.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
 <87r45rzsbj.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmqH+tred=mCkc9Ug2jj29iABr2iAavO4LX23JFmpJxpDg@mail.gmail.com>

On Mon, Mar 24, 2014 at 11:36 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> def get_oneth_element_index(item):
>>     return item[1].index
>> L.sort(key=get_oneth_element_index)
>>
>> Or do you just shortcut the whole thing by inlining it?
>>
>> L.sort(key=lambda item:item[1].index)
>
> I still prefer the "def" variant. It even allows you to clarify the
> meaning of the tuple slot by using a nicer name.

It's the index of element 1. What more do you need to know? Is it
actually any help to give that a name? All you gain is a chance for
the name, the purpose, and the functionality to come into
disagreement.

ChrisA


From nispray at gmail.com  Mon Mar 24 09:37:31 2014
From: nispray at gmail.com (Wesley)
Date: Mon, 24 Mar 2014 06:37:31 -0700 (PDT)
Subject: gdb python how to output integer for examine memory
In-Reply-To: <mailman.8447.1395663507.18130.python-list@python.org>
References: <e1e8c3a2-5d8d-4aae-9a5d-82af79be8c4c@googlegroups.com>
 <mailman.8447.1395663507.18130.python-list@python.org>
Message-ID: <cb8140fb-ee67-453c-ab21-24e24e705cb4@googlegroups.com>

Hi Dave,
  Thanks for your response.
It's just a simple script for test:-)
My concern is use gdb to monitor variable in memory within python process.
For details, in my origin post, just wanna why cannot output interger value from the address.

Maybe here is not right for gdb python question..but seems I cannot post question at another gdb group.

So, post here, since it's also related to python,in case anyone knowns this.
Sorry for that.

Wesley

? 2014?3?24????UTC+8??8?22?59??Dave Angel???
> Wesley <nispray at gmail.com> Wrote in message:
> 
> > Hi all,
> 
> >   I am trying to use gdb debug python script.
> 
> > I am using gdb7.7 and python2.7.6, here is my simple test script: 
> 
> > import time
> 
> > 
> 
> > def next(i):
> 
> >     time.sleep(10)
> 
> >     i = 1 - i
> 
> > 
> 
> > i = 1
> 
> > while True:
> 
> >     next(i)
> 
> > When this script running, gdb attach to it, and here is snippet:
> 
> > 
> 
> 
> 
> I cannot help with gdb, but I can point out that you have two
> 
>  separate variables here. Decrement ing the local has no effect on
> 
>  the global value.
> 
> 
> 
> The preferred way is to return any values from the function that
> 
>  you want to use after it exits. 
> 
> def next(i):
> 
>      time.sleep(10)
> 
>      i = 1 - i
> 
>      return i
> 
> 
> 
> i = 1
> 
> while True:
> 
>     i =next(i)
> 
> 
> 
> Another possibility,  generally a bad idea,  is declaring i global
> 
>  in the function. 
> 
> 
> 
> -- 
> 
> DaveA



From steve+comp.lang.python at pearwood.info  Mon Mar 24 10:04:59 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 24 Mar 2014 14:04:59 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
Message-ID: <53303b8a$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Mon, 24 Mar 2014 22:49:38 +1100, Chris Angelico wrote:

> On Mon, Mar 24, 2014 at 8:55 PM, Marko Rauhamaa <marko at pacujo.net>
> wrote:

>> You never *need* (Python's) lambda for anything. Inner functions are
>> more capable and almost always more readable. It doesn't hurt to have
>> lambda, but I don't find any use for it, either.

Marko has missed an obvious use: lambda is the *only* solution when you 
need a function embedded in an expression. You simply cannot do so 
otherwise. It is truly astonishing that two people here who are such keen 
supporters of functional programming, Marko and Mark Harris, are so 
dismissive of lambda, and so forced to write declarative code using def.


> They're often not more readable. A lot of people seem to equate
> "verbose" with "readable", possibly by faulty extrapolation from
> unreadably crunched code with one-letter variables and no line breaks.
> But which of these is truly more readable?
> 
> squares = []
> for n in range(30):
>     squares.append(n * n)
> 
> squares = [n * n for n in range(30)]

Readable for whom?

List comprehension syntax is often completely obscure to beginners. A 
beginner would say that the explicit for-loop is more readable.

Actually, a *real* beginner, whose main programming experience before 
Python was Pascal, would probably even say that the first example was an 
unreadable mess. What's range(30)? What's this ".append" business? What 
does [] mean? I know this because I was this beginner, once. The first 
few times I tried reading Python code, I couldn't make head or tail of 
it. "for" I recognised, because it was the same keyword as Pascal and 
Hypertalk use. Pretty much everything else might as well have been 
Bulgarian.

This was before the public internet, there was no Google, no tutorials I 
could look up. It was only after a colleague convinced me that it would 
be a good language to learn that I bought an actual dead tree book and 
sat down and learned how to read Python.

I think that Python's reputation of being "executable pseudo-code" is 
sometimes harmful. It fools people into thinking that unless Aunt Tilly 
can understand a language feature, it's somehow a failure. Hence the 
arguments by Mark against lambda.

http://www.catb.org/jargon/html/A/Aunt-Tillie.html

But nobody expects Aunt Tilly to read Scheme or C++ or Go without at 
least a bit of learning -- or even Esperanto or French or Latin. You 
still need to learn the syntax and the vocabulary, and have some idea of 
the basic concepts. The same applies to Python. The learning curve may be 
more gentle, but there is still a learning curve. And that is perfectly 
fine.

So while I agree with you that, to a moderately fluent Python speaker, 
not a beginner but not an expert either, the list comprehension is more 
readable, for a beginner (one who has a basic Python vocab but isn't 
fluent yet) the for-loop will probably be more readable.


> Similarly, there are plenty of cases where a nameless function is MUCH
> clearer than breaking it out into a separate def and then using the name
> once. Do you name the function for what it does internally?
> 
> def get_oneth_element_index(item):
>     return item[1].index
> L.sort(key=get_oneth_element_index)
> 
> Or for how you're using it?
> 
> def keyfunc(item):
>     return item[1].index
> L.sort(key=keyfunc)

Why not both?! Don't forget to make it private so some other piece of 
code doesn't use it. Or better still, delete it when done!

def _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L(item):
    return item[1].index

L.sort(key=_get_oneth_element_index_to_use_as_keyfunc_when_sorting_L)
del _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L

Four lines of code to do what lambda lets you do in one. And people still 
insist that lambda is pointless. Maybe they're being paid by the line.


> Or do you just shortcut the whole thing by inlining it?
> 
> L.sort(key=lambda item:item[1].index)

Exactly.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rustompmody at gmail.com  Mon Mar 24 10:19:20 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 07:19:20 -0700 (PDT)
Subject: Question about Source Control
In-Reply-To: <mailman.8190.1395061611.18130.python-list@python.org>
References: <mailman.8190.1395061611.18130.python-list@python.org>
Message-ID: <19d3ddc9-0fb9-476d-a117-e5f174eca85c@googlegroups.com>

On Monday, March 17, 2014 6:36:33 PM UTC+5:30, Frank Millman wrote:
> Hi all

> I know I *should* be using a Source Control Management system, but at 
> present I am not. I tried to set up Mercurial a couple of years ago, but I 
> think I set it up wrongly, as I got myself confused and found it more of a 
> hindrance than a help. Now I am ready to try again, but I want to avoid my 
> earlier mistakes.

> I understand the concept, and I understand the importance, so I do not need 
> reminding of those. What I would like help with is the basic setup. I could 
> subscribe to the Mercurial mailing list and ask there, but I am hoping for a 
> kick-start here. Here is my setup.

> All my source code resides on an old Linux server, which I switch on in the 
> morning and switch off at night, but otherwise hardly ever look at. It uses 
> 'samba' to allow sharing with Windows, and 'nfs' to allow sharing with other 
> Linux machines.

> I need to test my program on Windows and on Linux, so I run it from both at 
> various times. On Windows I have a 'mapped drive' pointing to the source 
> code. On Linux I use a third machine, running a recent Fedora, using nfs to 
> mount a directory pointing to the source code. Obviously each machine has 
> its own version of Python installed.

> I do my development on the Windows machine. I use TextPad, a simple text 
> editor, which works fine for my purposes. It uses the mapped drive to point 
> to the source code.

> So where should I install the SCM, and how should I set it up so that I can 
> access the latest version from any machine?

> Any hints will be appreciated.

Seen this??
Yeah may not apply directly to your use-case buts seems worth a read
https://www.kernel.org/pub/software/scm/git/docs/gitworkflows.html

[At command line
$ git help -w workflows
will give you the same
]


From breamoreboy at yahoo.co.uk  Mon Mar 24 10:21:02 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 24 Mar 2014 14:21:02 +0000
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <87r45rzsbj.fsf@elektro.pacujo.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
 <87r45rzsbj.fsf@elektro.pacujo.net>
Message-ID: <lgpevh$maf$1@ger.gmane.org>

On 24/03/2014 12:36, Marko Rauhamaa wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> Similarly, there are plenty of cases where a nameless function is MUCH
>> clearer than breaking it out into a separate def and then using the
>> name once. Do you name the function for what it does internally?
>>
>> def get_oneth_element_index(item):
>>      return item[1].index
>> L.sort(key=get_oneth_element_index)
>>
>> Or for how you're using it?
>>
>> def keyfunc(item):
>>      return item[1].index
>> L.sort(key=keyfunc)
>>
>> Or do you just shortcut the whole thing by inlining it?
>>
>> L.sort(key=lambda item:item[1].index)
>
> I still prefer the "def" variant. It even allows you to clarify the
> meaning of the tuple slot by using a nicer name.
>

Each to their own.  Here give me the lambda version any day of the week.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From steve+comp.lang.python at pearwood.info  Mon Mar 24 10:39:51 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 24 Mar 2014 14:39:51 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
 <87r45rzsbj.fsf@elektro.pacujo.net>
 <mailman.8448.1395665601.18130.python-list@python.org>
Message-ID: <533043b7$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Mon, 24 Mar 2014 23:53:12 +1100, Chris Angelico wrote:

> On Mon, Mar 24, 2014 at 11:36 PM, Marko Rauhamaa <marko at pacujo.net>
> wrote:
>>> def get_oneth_element_index(item):
>>>     return item[1].index
>>> L.sort(key=get_oneth_element_index)
>>>
>>> Or do you just shortcut the whole thing by inlining it?
>>>
>>> L.sort(key=lambda item:item[1].index)
>>
>> I still prefer the "def" variant. It even allows you to clarify the
>> meaning of the tuple slot by using a nicer name.
> 
> It's the index of element 1. What more do you need to know? Is it
> actually any help to give that a name? All you gain is a chance for the
> name, the purpose, and the functionality to come into disagreement.



# Magic constants are wicked. Never use a constant without naming it.
ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L = 1

# <summary>
#     key func used when sorting L, returns item's 1th elem index method
# </summary>
# <function_name>
#    _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L
# </function_name>
# <author>Steven D'Aprano</author>
# <date_created>2014-03-25</date_created>
# <date_modified>2014-03-25</date_modified>
# <revision>1</revision>
# <param name="item">item to be sorted</param>
# <returns>index method of the oneth element</returns>
# <raises>NameError</raises>  # FIXME can this fail any other way?
def _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L(item):
    """Private key function for sorting list L.

    Returns the index method of element 1 of the given item.

    Example of use:

    >>> item = (None, '')
    >>> _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L(item)
    <built-in method index of str object at ...>

    Relies on global constant ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L.
    May raise NameError if that constant is missing.

    Warning: do not use this for anything else.
    """
    return item[ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L].index

L.sort(key=_get_oneth_element_index_to_use_as_keyfunc_when_sorting_L)
del _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L
# Better to be safe than sorry.
del ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L




Definitely being paid by the line :-)


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From prabir.kr.sarkar at gmail.com  Mon Mar 24 11:15:08 2014
From: prabir.kr.sarkar at gmail.com (Prabir Kr Sarkar)
Date: Mon, 24 Mar 2014 20:45:08 +0530
Subject: TypeError in HMAC module.
Message-ID: <CADjSiz7y2Zx8RDtE5n8gRMQ=0A3mcB_s548R4FXkBO1cfA-vog@mail.gmail.com>

Hi,
   I am trying to create a hashed message for authentication for a REST API
call. I have got the key from a keyring as :-

key = keyring.get_password('AWS_keyring','username')

& calculating the signature as :-
signature = hmac(key, message.encode('UTF-8'),
hashlib.sha1).digest().encode('base64')[:-1]

But, while running the script I get the following errors :-

  File "/usr/lib64/python2.6/hmac.py", line 133, in new
    return HMAC(key, msg, digestmod)
  File "/usr/lib64/python2.6/hmac.py", line 72, in __init__
*    self.outer.update(key.translate(trans_5C))*
*TypeError: character mapping must return integer, None or unicode*

My python version is :-

# python -V
Python 2.6.9

Can someone please help me as to how I can resolve this issue. Thanks in
advance.

-- 
*Thanks and Regards*
*Prabir Sarkar*
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From breamoreboy at yahoo.co.uk  Mon Mar 24 11:22:50 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 24 Mar 2014 15:22:50 +0000
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <533043b7$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
 <87r45rzsbj.fsf@elektro.pacujo.net>
 <mailman.8448.1395665601.18130.python-list@python.org>
 <533043b7$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgpiia$k42$1@ger.gmane.org>

On 24/03/2014 14:39, Steven D'Aprano wrote:
> On Mon, 24 Mar 2014 23:53:12 +1100, Chris Angelico wrote:
>
>> On Mon, Mar 24, 2014 at 11:36 PM, Marko Rauhamaa <marko at pacujo.net>
>> wrote:
>>>> def get_oneth_element_index(item):
>>>>      return item[1].index
>>>> L.sort(key=get_oneth_element_index)
>>>>
>>>> Or do you just shortcut the whole thing by inlining it?
>>>>
>>>> L.sort(key=lambda item:item[1].index)
>>>
>>> I still prefer the "def" variant. It even allows you to clarify the
>>> meaning of the tuple slot by using a nicer name.
>>
>> It's the index of element 1. What more do you need to know? Is it
>> actually any help to give that a name? All you gain is a chance for the
>> name, the purpose, and the functionality to come into disagreement.
>
>
>
> # Magic constants are wicked. Never use a constant without naming it.
> ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L = 1
>
> # <summary>
> #     key func used when sorting L, returns item's 1th elem index method
> # </summary>
> # <function_name>
> #    _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L
> # </function_name>
> # <author>Steven D'Aprano</author>
> # <date_created>2014-03-25</date_created>
> # <date_modified>2014-03-25</date_modified>
> # <revision>1</revision>
> # <param name="item">item to be sorted</param>
> # <returns>index method of the oneth element</returns>
> # <raises>NameError</raises>  # FIXME can this fail any other way?
> def _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L(item):
>      """Private key function for sorting list L.
>
>      Returns the index method of element 1 of the given item.
>
>      Example of use:
>
>      >>> item = (None, '')
>      >>> _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L(item)
>      <built-in method index of str object at ...>
>
>      Relies on global constant ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L.
>      May raise NameError if that constant is missing.
>
>      Warning: do not use this for anything else.
>      """
>      return item[ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L].index
>
> L.sort(key=_get_oneth_element_index_to_use_as_keyfunc_when_sorting_L)
> del _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L
> # Better to be safe than sorry.
> del ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L
>
> Definitely being paid by the line :-)
>

One of the finest examples of extracting the urine I've ever read. 
Please keep up the good work.  Ah but wait, down voted on the grounds 
that there are no unit tests and, far more importantly, it doesn't fit 
on one line (unless you use gg that is).  There is also no proof that 
it's been committed to your source control system after going through 
its code review.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rustompmody at gmail.com  Mon Mar 24 12:00:54 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 09:00:54 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <53303b8a$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
 <53303b8a$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <7beccf79-0036-4a90-8bc2-2afae28c1213@googlegroups.com>

On Monday, March 24, 2014 7:34:59 PM UTC+5:30, Steven D'Aprano wrote:
> On Mon, 24 Mar 2014 22:49:38 +1100, Chris Angelico wrote:

> > wrote:

> >> You never *need* (Python's) lambda for anything. Inner functions are
> >> more capable and almost always more readable. It doesn't hurt to have
> >> lambda, but I don't find any use for it, either.

> Marko has missed an obvious use: lambda is the *only* solution when you 
> need a function embedded in an expression. You simply cannot do so 
> otherwise. It is truly astonishing that two people here who are such keen 
> supporters of functional programming, Marko and Mark Harris, are so 
> dismissive of lambda, and so forced to write declarative code using def.

> > They're often not more readable. A lot of people seem to equate
> > "verbose" with "readable", possibly by faulty extrapolation from
> > unreadably crunched code with one-letter variables and no line breaks.
> > But which of these is truly more readable?
> > squares = []
> > for n in range(30):
> >     squares.append(n * n)
> > squares = [n * n for n in range(30)]

> Readable for whom?

> List comprehension syntax is often completely obscure to beginners. A 
> beginner would say that the explicit for-loop is more readable.

> Actually, a *real* beginner, whose main programming experience before 
> Python was Pascal, would probably even say that the first example was an 
> unreadable mess. What's range(30)? What's this ".append" business? What 
> does [] mean? I know this because I was this beginner, once. The first 
> few times I tried reading Python code, I couldn't make head or tail of 
> it. "for" I recognised, because it was the same keyword as Pascal and 
> Hypertalk use. Pretty much everything else might as well have been 
> Bulgarian.

> This was before the public internet, there was no Google, no tutorials I 
> could look up. It was only after a colleague convinced me that it would 
> be a good language to learn that I bought an actual dead tree book and 
> sat down and learned how to read Python.

> I think that Python's reputation of being "executable pseudo-code" is 
> sometimes harmful. It fools people into thinking that unless Aunt Tilly 
> can understand a language feature, it's somehow a failure. Hence the 
> arguments by Mark against lambda.

> http://www.catb.org/jargon/html/A/Aunt-Tillie.html

> But nobody expects Aunt Tilly to read Scheme or C++ or Go without at 
> least a bit of learning -- or even Esperanto or French or Latin. You 
> still need to learn the syntax and the vocabulary, and have some idea of 
> the basic concepts. The same applies to Python. The learning curve may be 
> more gentle, but there is still a learning curve. And that is perfectly 
> fine.

Ok so far

> So while I agree with you that, to a moderately fluent Python speaker, 
> not a beginner but not an expert either, the list comprehension is more 
> readable, for a beginner (one who has a basic Python vocab but isn't 
> fluent yet) the for-loop will probably be more readable.

And now I wonder...
The case you are wanting to make and the case you are ending up making
seem to be opposite: 

If it is so as you say that for "the beginner (one who has a basic 
Python vocab but isn't fluent yet)"
the for-loop is more readable than the for-in-compr
it then suggests that those more experienced taking/helping the
beginners at 0 to the stage of "basic vocab-but-not-yet fluent" are
choosing a sub-optimal route.

Remember that you started by reminding that for an absolute beginner,
everything is 'Bulgarian' not just list comprehensions.

Then how come some things become accessible faster than others?
It may be that those things are actually easier (in some objective sense)
But it may also reveal a prejudice of the teachers.

As for the other argument -- python lambda is BAD -- Ive currently run out of pepper for sprinkling on these flames :-)
I'll just make a few points:

1. Miranda the predecessor of Haskell had no lambda.
Local defs + curried convention + operator sections was considered more than 
sufficient for functional programming

2. Lisp was the originator of lambda (in programming languages) and it screwed up the semantics so badly that
 a. It had to be corrected at high cost 25 years later -- aka scheme and common lisp
 b. Some doyens of functional programming have suggested that lisp is a major setback for the acceptance of functional programming, eg
http://www.cs.kent.ac.uk/people/staff/dat/miranda/wadler87.pdf

3. One basic tenet of ? calculus
foo = ? x . exp
is equivalent to the more traditional
foo(x) = exp

is a little uh-uh in haskell thanks to the notorious monomorphism restriction
http://www.haskell.org/haskellwiki/Monomorphism_restriction

So if FP = ? calculus, Haskell does not quite make it!!
 


From peter.byaruhanga at utamu.ac.ug  Mon Mar 24 12:20:26 2014
From: peter.byaruhanga at utamu.ac.ug (mikie)
Date: Mon, 24 Mar 2014 09:20:26 -0700 (PDT)
Subject: String modifying error, trying to delete data in string
Message-ID: <fafdc0ba-573b-4c48-a6b6-263d2cdeb7eb@googlegroups.com>

Here is some code:
       import socket,sys

       s=socket.socket()
       port=int(sys.argv[1]) 
       s.bind(("127.0.0.1",port))
       s.listen(2) 
       cls,addr=s.accept()

       data=cls.recv(1024)
       f=data.pop("Proxy-Connection")
       cls.close()

Im trying to delete some headers in the request but get an error saying:
'str' object has no attribute 'pop'

How can I modify data received from the client?


From breamoreboy at yahoo.co.uk  Mon Mar 24 12:31:51 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 24 Mar 2014 16:31:51 +0000
Subject: String modifying error, trying to delete data in string
In-Reply-To: <fafdc0ba-573b-4c48-a6b6-263d2cdeb7eb@googlegroups.com>
References: <fafdc0ba-573b-4c48-a6b6-263d2cdeb7eb@googlegroups.com>
Message-ID: <lgpmjo$9mv$1@ger.gmane.org>

On 24/03/2014 16:20, mikie wrote:
> Here is some code:
>         import socket,sys
>
>         s=socket.socket()
>         port=int(sys.argv[1])
>         s.bind(("127.0.0.1",port))
>         s.listen(2)
>         cls,addr=s.accept()
>
>         data=cls.recv(1024)
>         f=data.pop("Proxy-Connection")
>         cls.close()
>
> Im trying to delete some headers in the request but get an error saying:
> 'str' object has no attribute 'pop'
>
> How can I modify data received from the client?
>

Strings are immutable so you'll need string methods to manipulate your 
data see 
http://docs.python.org/3/library/stdtypes.html#text-sequence-type-str

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From steve+comp.lang.python at pearwood.info  Mon Mar 24 13:09:11 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 24 Mar 2014 17:09:11 GMT
Subject: String modifying error, trying to delete data in string
References: <fafdc0ba-573b-4c48-a6b6-263d2cdeb7eb@googlegroups.com>
Message-ID: <533066b7$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Mon, 24 Mar 2014 09:20:26 -0700, mikie wrote:

> Im trying to delete some headers in the request but get an error saying:
> 'str' object has no attribute 'pop'

What sort of object is data? What do you expect it to be, and what it is 
actually?

Given that you are calling data.pop("Proxy-Connection"), that suggests to 
me that you think data is a dict. The error message given tells you that 
data is a str.

> How can I modify data received from the client?

The same as any string: make a copy with whatever modifications you want. 
Strings have a replace method; you can use the re module to use regexes; 
you can slice them with some_string[start:end] syntax, etc. But it looks 
to me like you might be better off using a higher-level protocol rather 
than using socket. What sort of data are you expecting back?



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ian.g.kelly at gmail.com  Mon Mar 24 13:24:00 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 24 Mar 2014 11:24:00 -0600
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <87bnwv2a5v.fsf@elektro.pacujo.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
Message-ID: <CALwzidk71U=A_PwBDRbTc2pEDP5nCLsnRb0z-qLT8C8=JLGgWA@mail.gmail.com>

On Mon, Mar 24, 2014 at 3:55 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Ian Kelly <ian.g.kelly at gmail.com>:
>
>> If lambda were going to be deprecated and removed then it already
>> would have happened in Python 3, because Guido tried to do precisely
>> that. I'm not sure what the reasons were for keeping it in the end
>> (according to PEP 3099 it was because nobody suggested a suitable
>> replacement), but if he couldn't get rid of it then, he never will.
>
> You never *need* (Python's) lambda for anything. Inner functions are
> more capable and almost always more readable. It doesn't hurt to have
> lambda, but I don't find any use for it, either.

So what? One might say the same thing about comprehensions -- loops
are more capable and almost always more readable.


From vincent at vincentdavis.net  Mon Mar 24 13:50:07 2014
From: vincent at vincentdavis.net (Vincent Davis)
Date: Mon, 24 Mar 2014 11:50:07 -0600
Subject: Merge/append CSV files with different headers
Message-ID: <CALyJZZWmAWP=STfZGpvN_NexxS=7DA9GrxOAC+2ibUNgkJtM1Q@mail.gmail.com>

I have several csv file I need to append (vertically). They have different
but overlapping headers. For example;
file1 headers ['a', 'b', 'c']
file2 headers ['d', 'e']
file3 headers ['c', 'd']

Is there a better way than this
import csv
def merge_csv(fileList, newFileName):
    allHeaders = set([])
    for afile in fileList:
        with open(afile, 'rb') as csvfilesin:
            eachheader = csv.reader(csvfilesin, delimiter=',').next()
            allHeaders.update(eachheader)
    print(allHeaders)
    with open(newFileName, 'wb') as csvfileout:
        outfile = csv.DictWriter(csvfileout, allHeaders)
        outfile.writeheader()
        for afile in fileList:
            print('***'+afile)
            with open(afile, 'rb') as csvfilesin:
                rows = csv.DictReader(csvfilesin, delimiter=',')
                for r in rows:
                    print(allHeaders.issuperset(r.keys()))
                    outfile.writerow(r)

Vincent Davis
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From breamoreboy at yahoo.co.uk  Mon Mar 24 14:24:10 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 24 Mar 2014 18:24:10 +0000
Subject: Merge/append CSV files with different headers
In-Reply-To: <CALyJZZWmAWP=STfZGpvN_NexxS=7DA9GrxOAC+2ibUNgkJtM1Q@mail.gmail.com>
References: <CALyJZZWmAWP=STfZGpvN_NexxS=7DA9GrxOAC+2ibUNgkJtM1Q@mail.gmail.com>
Message-ID: <lgpt84$3dg$1@ger.gmane.org>

On 24/03/2014 17:50, Vincent Davis wrote:
> I have several csv file I need to append (vertically). They have
> different but overlapping headers. For example;
> file1 headers ['a', 'b', 'c']
> file2 headers ['d', 'e']
> file3 headers ['c', 'd']
>
> Is there a better way than this
> import csv
> def merge_csv(fileList, newFileName):
>      allHeaders = set([])
>      for afile in fileList:
>          with open(afile, 'rb') as csvfilesin:
>              eachheader = csv.reader(csvfilesin, delimiter=',').next()
>              allHeaders.update(eachheader)
>      print(allHeaders)
>      with open(newFileName, 'wb') as csvfileout:
>          outfile = csv.DictWriter(csvfileout, allHeaders)
>          outfile.writeheader()
>          for afile in fileList:
>              print('***'+afile)
>              with open(afile, 'rb') as csvfilesin:
>                  rows = csv.DictReader(csvfilesin, delimiter=',')
>                  for r in rows:
>                      print(allHeaders.issuperset(r.keys()))
>                      outfile.writerow(r)
>
> Vincent Davis
>

I haven't looked too hard at your code but guess you could simplify it 
by using the fieldnames parameter to the DictReader class or making use 
of the Sniffer class.  See 
http://docs.python.org/3/library/csv.html#module-csv


-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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From harrismh777 at gmail.com  Mon Mar 24 14:58:16 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 13:58:16 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8443.1395655163.18130.python-list@python.org>
Message-ID: <lgpv85$rdq$1@speranza.aioe.org>

On 3/24/14 4:58 AM, Mark Lawrence wrote:
> Where do you get reduce from if it's not in the standard library?

    That was "a" proposal for 3000. Its there, but its not on the 
built-ins; ie., you have to import it.  The confusion: why reduce, why 
not filter, nor map?  {rhetorical}

> As for lambda I've no real interest in it, other than when copying examples
> where it's used to (say) provide a key function.
>

This is one of my main points to Steven. In my experience "most" people 
do not intend to use lambda for anything; they are trying to sort this 
or that and don't quite know how to get the key right and some helpful 
somebody gives them a key=lambda yadda yadda .  They use it, and it 
works, but they are scratching their head saying to themselves, "what it 
that, how does it work, how can I understand it and on and on".

That is what we mean by confusing. Or another really great example is 
this thread. Somebody asks about a language feature and somebody else 
helpfully answers the question by providing them with a similar lambda!!

Its the programmer's equivalent of explanation by reference to a more 
complicated analogy; which leaves the OP left with, "Thanks for all the 
responses".

marcus

PS  You are absolutely right, all the expanding double spaces become 
very annoying when viewed on Thunderbird; it is exasperating, genuinely.





From rosuav at gmail.com  Mon Mar 24 15:05:55 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 06:05:55 +1100
Subject: TypeError in HMAC module.
In-Reply-To: <CADjSiz7y2Zx8RDtE5n8gRMQ=0A3mcB_s548R4FXkBO1cfA-vog@mail.gmail.com>
References: <CADjSiz7y2Zx8RDtE5n8gRMQ=0A3mcB_s548R4FXkBO1cfA-vog@mail.gmail.com>
Message-ID: <CAPTjJmqOZj66rCugmdX229koRqUd4MJ2=1BwUMvPs1Kh1afpSg@mail.gmail.com>

On Tue, Mar 25, 2014 at 2:15 AM, Prabir Kr Sarkar
<prabir.kr.sarkar at gmail.com> wrote:
> Hi,
>    I am trying to create a hashed message for authentication for a REST API
> call. I have got the key from a keyring as :-
>
> key = keyring.get_password('AWS_keyring','username')
>
> & calculating the signature as :-
> signature = hmac(key, message.encode('UTF-8'),
> hashlib.sha1).digest().encode('base64')[:-1]

I can't "import keyring", so either that's a module that isn't in the
Python standard library, or "keyring" is some object you've
instantiated. My crystal ball says this might be something to do with
Amazon Web Services, but it's hard to be sure. Can you please help us
out here by telling us all the dependencies of your code, and also
showing us a complete runnable program?

http://www.sscce.org/

Thanks!

ChrisA


From rosuav at gmail.com  Mon Mar 24 15:12:47 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 06:12:47 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <53303b8a$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
 <53303b8a$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqZ1ekiBEpGDtj-P_TVJ+=0R2CMVh4GOfCvL5vci=qm2g@mail.gmail.com>

On Tue, Mar 25, 2014 at 1:04 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
>> But which of these is truly more readable?
>>
>> squares = []
>> for n in range(30):
>>     squares.append(n * n)
>>
>> squares = [n * n for n in range(30)]
>
> Readable for whom?
>
> List comprehension syntax is often completely obscure to beginners. A
> beginner would say that the explicit for-loop is more readable.
>
> Actually, a *real* beginner, whose main programming experience before
> Python was Pascal, would probably even say that the first example was an
> unreadable mess. What's range(30)? What's this ".append" business? What
> does [] mean? I know this because I was this beginner, once. The first
> few times I tried reading Python code, I couldn't make head or tail of
> it. "for" I recognised, because it was the same keyword as Pascal and
> Hypertalk use. Pretty much everything else might as well have been
> Bulgarian.

Actually, that's a very good point. Python's for loop is more often
called a foreach loop in other languages, and Python completely lacks
any concept of a "classic" iteration-over-integer for loop. That is a
point of confusion. However, that's going to come up on both branches,
so it's not really a mark against either.

Incidentally, I've often modified my loop counter, in C or REXX or any
other language. About the only situation where I actually miss it in
Python, though, is iterating over a list and mutating the list on the
way through; and even that can often be done in other ways (maybe a
list comp, filtering out some of the elements?). It's amazing how
something can be so utterly fundamental (I mean, come ON! Who can
imagine a language with no equivalent of the basic "do i=1 to 10"
(REXX) or "for (int i=0;i<10;++i)" (C++) loop???) and yet so
dispensable.

ChrisA


From breamoreboy at yahoo.co.uk  Mon Mar 24 15:13:13 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 24 Mar 2014 19:13:13 +0000
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <lgpv85$rdq$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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 <lgpv85$rdq$1@speranza.aioe.org>
Message-ID: <lgq043$dv2$1@ger.gmane.org>

On 24/03/2014 18:58, Mark H Harris wrote:
> On 3/24/14 4:58 AM, Mark Lawrence wrote:
>> Where do you get reduce from if it's not in the standard library?
>
>     That was "a" proposal for 3000. Its there, but its not on the
> built-ins; ie., you have to import it.  The confusion: why reduce, why
> not filter, nor map?  {rhetorical}

So it is in the standard library then.  And I'm not confused, seeing 
this must have been decided years ago as Python 3 was released some five 
years ago.

>
>> As for lambda I've no real interest in it, other than when copying
>> examples
>> where it's used to (say) provide a key function.
>>
>
> This is one of my main points to Steven. In my experience "most" people
> do not intend to use lambda for anything; they are trying to sort this
> or that and don't quite know how to get the key right and some helpful
> somebody gives them a key=lambda yadda yadda .  They use it, and it
> works, but they are scratching their head saying to themselves, "what it
> that, how does it work, how can I understand it and on and on".

More fool them, I write Python as I let it take away the head 
scratching, not add to it.  If I wanted to start head scratching maybe 
I'd go and investigate what line 247 of gcmodule.c does, but funnily 
enough I've never been there, and don't intend starting now.

>
> That is what we mean by confusing. Or another really great example is
> this thread. Somebody asks about a language feature and somebody else
> helpfully answers the question by providing them with a similar lambda!!

One of the joys of this list from my POV, YMMV.

>
> Its the programmer's equivalent of explanation by reference to a more
> complicated analogy; which leaves the OP left with, "Thanks for all the
> responses".
>
> marcus
>
> PS  You are absolutely right, all the expanding double spaces become
> very annoying when viewed on Thunderbird; it is exasperating, genuinely.
>

Yep, but like I said the situation has improved, partly thanks to the 
guys who improved the words on the wiki showing how to successfuly use 
gg.  Thanks fellas :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From ian.g.kelly at gmail.com  Mon Mar 24 15:12:54 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 24 Mar 2014 13:12:54 -0600
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lgpv85$rdq$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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Message-ID: <CALwzidm8kZ4bGEXJBK1akU-C+AvJCkA7f9E4T=cgwWM5zLLENQ@mail.gmail.com>

On Mon, Mar 24, 2014 at 12:58 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> That is what we mean by confusing. Or another really great example is this
> thread. Somebody asks about a language feature and somebody else helpfully
> answers the question by providing them with a similar lambda!!

That is not in fact how the topic of lambda arose in this thread.
Rustom Mody brought up the binding behavior in a tangent specifically
to complain about it, and that was the first mention of lambda in the
thread.


From rosuav at gmail.com  Mon Mar 24 15:22:28 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 06:22:28 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lgpv85$rdq$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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Message-ID: <CAPTjJmruMJavv4DgSjKxE_fHUaHkT8UshT_2VO+L19VxVLgryw@mail.gmail.com>

On Tue, Mar 25, 2014 at 5:58 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> Its there, but its not on the built-ins; ie., you have to import it.  The
> confusion: why reduce, why not filter, nor map?  {rhetorical}

In other languages with those three, and without list/array
comprehensions, I've used filter occasionally and map reasonably
often, but I don't remember the last time I used reduce. Actually,
Pike has special syntax that can take the place of map sometimes, so I
might use filter more often than map in Pike code, because these don't
need explicit map calls:

//Suppose that clients is an array of connected clients on some server
clients->sockets->write("System message: blah blah blah\n");

Indexing an array (the -> is like Python's . as Pike's . is resolved
at compile time) produces an array, effectively mapping the elements
through "lambda x: x->sockets" and ditto for "->write". Calling an
array calls all the non-empty elements in it, with the same
argument(s), and produces an array of return values. (In this case, I
don't care about the return values, which will simply be the number of
bytes written to each socket. If there's a problem, it'll throw an
exception.) Huh. Even with that, and the [*] automap syntax, and such,
I still use map far more often than filter... and filter orders of
magnitude more often than reduce.

Aside: You'll often hear people talking about "map-reduce" with big
data. Python supports that. Look!

>>> map.__reduce__
<method '__reduce__' of 'map' objects>

Oh wait, that's nothing to do with reduce()...

*ducks for cover*

ChrisA


From ian.g.kelly at gmail.com  Mon Mar 24 15:42:03 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 24 Mar 2014 13:42:03 -0600
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <CAPTjJmqZ1ekiBEpGDtj-P_TVJ+=0R2CMVh4GOfCvL5vci=qm2g@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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 <lgoh7j$otg$1@speranza.aioe.org>
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 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
 <53303b8a$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmqZ1ekiBEpGDtj-P_TVJ+=0R2CMVh4GOfCvL5vci=qm2g@mail.gmail.com>
Message-ID: <CALwzidk3qyeJvPZQ6CX_qmG00NNqhEwsb67WL_9eW1o9dHqdcw@mail.gmail.com>

On Mon, Mar 24, 2014 at 1:12 PM, Chris Angelico <rosuav at gmail.com> wrote:
> Incidentally, I've often modified my loop counter, in C or REXX or any
> other language. About the only situation where I actually miss it in
> Python, though, is iterating over a list and mutating the list on the
> way through; and even that can often be done in other ways (maybe a
> list comp, filtering out some of the elements?). It's amazing how
> something can be so utterly fundamental (I mean, come ON! Who can
> imagine a language with no equivalent of the basic "do i=1 to 10"
> (REXX) or "for (int i=0;i<10;++i)" (C++) loop???) and yet so
> dispensable.

I'm not sure "fundamental" is the right word.  A for loop is just a
while loop with some syntactic sugar.  For that matter, a while loop
is just a structured goto...


From rosuav at gmail.com  Mon Mar 24 15:44:39 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 06:44:39 +1100
Subject: Merge/append CSV files with different headers
In-Reply-To: <CALyJZZWmAWP=STfZGpvN_NexxS=7DA9GrxOAC+2ibUNgkJtM1Q@mail.gmail.com>
References: <CALyJZZWmAWP=STfZGpvN_NexxS=7DA9GrxOAC+2ibUNgkJtM1Q@mail.gmail.com>
Message-ID: <CAPTjJmpmbQWxrSBmsyiYOvPbVJGwmzDoRv_8pQh+bZ9=8iQpsg@mail.gmail.com>

On Tue, Mar 25, 2014 at 4:50 AM, Vincent Davis <vincent at vincentdavis.net> wrote:
> I have several csv file I need to append (vertically). They have different
> but overlapping headers. For example;
> file1 headers ['a', 'b', 'c']
> file2 headers ['d', 'e']
> file3 headers ['c', 'd']
>
> Is there a better way than this

Summary of your code:

1) Build up a set of all headers used, by opening each file and
reading the headers.
2) Go through each file a second time and write them out.

That seems like the best approach, broadly. You might be able to
improve it a bit (it might be tidier to open each file once, but since
you're using two different CSV readers, it'd probably not be), but by
and large, I'd say you have the right technique. Your processing time
here is going to be dominated by the actual work of copying.

The only thing you might want to consider is order. The headers all
have a set order to them, and it'd make sense to have the output come
out as ['a', 'b', 'c', 'd', 'e'] - the first three from the first
file, then adding in everything from subsequent files in the order
they were found. Could be done easily enough by using 'in' and
.append() on a list, rather than using a set. But if that doesn't
matter to you, or if something simple like "sort the headers
alphabetically" will do, then I think you basically have what you
want.

ChrisA


From rosuav at gmail.com  Mon Mar 24 15:45:53 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 06:45:53 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lgq043$dv2$1@ger.gmane.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8443.1395655163.18130.python-list@python.org>
 <lgpv85$rdq$1@speranza.aioe.org> <lgq043$dv2$1@ger.gmane.org>
Message-ID: <CAPTjJmraKs94oH+AEXp0eD+tFkUqNnrqaWaMrVJkqafPY3UjJQ@mail.gmail.com>

On Tue, Mar 25, 2014 at 6:13 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>>     That was "a" proposal for 3000. Its there, but its not on the
>> built-ins; ie., you have to import it.  The confusion: why reduce, why
>> not filter, nor map?  {rhetorical}
>
>
> So it is in the standard library then.  And I'm not confused, seeing this
> must have been decided years ago as Python 3 was released some five years
> ago.

Terminology issue, is all. It's not in the builtins, but it is in the
standard library.

ChrisA


From harrismh777 at gmail.com  Mon Mar 24 15:47:11 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 14:47:11 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <532fffaf$0$29878$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgq23s$44k$1@speranza.aioe.org>

On 3/24/14 4:49 AM, Steven D'Aprano wrote:
> There's no doubt that lambda is less-often useful than is the def
> statement. But not only is it still useful, but there is a continual
> stream of people asking for Python to make it *more useful* by allowing
> the body of a lambda to be a full block, not just a single statement.
> Guido has stated (although I cannot remember where, so cannot paste a
> link) that he accepts that in principle, so long as somebody comes up
> with acceptable syntax.

    Now, this will seem strange to you, but if lambda were expanded to 
include an entire block, well now, I would know two things:
   1) python has commitment to lambda    and
   2) lambda would become WAY more useful... ie., the only way to have a 
"block expression" embedded in an expression !  I'd vote for that. But 
as someone else noted, inner functions work as well (now) and are really 
more readable, so ...

> It's used in calendar, cgitb, configparser, difflib, decimal, functools,
> inspect, os, pydoc and others. Python is a programming language aimed at
> programmers, not a toy. It should include tools that programmers use,
> like threads, closures, first-class functions. And lambda.

    This is a valid point (its used a couple of hundred times). It could 
be replaced in probably of week of constant programming effort.  Neither 
here nor there, because nobody at this point is demanding it.

>> Lambda is a problem of confusion for scientists and other
>> mathematicians (amateur and otherwise) {snip}
>{snip}
> But nor should the confusion of somebody
> who doesn't know the language count for much.

    This is the main disagreement between the two of us on this topic. 
It should count for TONS; whole metric TONs. Because someone who 
understands python primarily, and after five years of coding (say me) 
somebody tells (me) to use lambda in a key clause so that my sort will 
work, or work better, or work "their" way; and I have no idea why I need 
this nameless function (after I find out that "that" is what it is!) 
Its confusing, and please contrast between complicated. I don't mind 
complicated, or extensive, or even hard, but when something is 
needlessly confusing, then why?

> Python's ints don't work exactly the same as ints do in some other
> languages, nor do Python's strings, nor is Python's object model
> precisely the same as that of some other languages. I think that it would
> be a ridiculous idea to discard int, str and the entire object system
> just because some people are surprised that Python doesn't behave exactly
> like some other language. I don't think lambda is any different.

    Your logic is faulty here.  Conceptually python's lambda doesn't 
work as expected, from contexts that define lambda and where lambda in 
functional programming is VERY important. For one thing, why would we 
want to "spell out" the word "lambda".    ( \x y -> x + y ) a b )
If we're going to use lambda, then use it.


> Other languages -- not even Lisp -- don't get to be the sole decider as
> to what counts as an anonymous function. Python's lambda may be limited,
> but it is a perfectly fine lambda for what it is intended to do.

    Is that the same as George W. Bush's "decider" ?

    I agree, and so does the link I referenced, for what it was designed 
to do, its powerful; esp if one needs to embed a function in an 
expression;  that is what lambda is for.

>> Its also confusing to sophisticated users of all
>> stripes who may not be aware of "lambda" at all.
>
> If they're not aware of lambda, how are they confused by it?

    See above.  They are recommended its use (maybe on this list) and 
they just don't get it; because its unnecessarily confusing.

> No, not really. I don't understand who your intended audience for Python
> is. If I were to try to guess, I suspect that you want to dumb Python
> down until it is like Dartmouth BASIC circa 1980 except without the line
> numbers and with a slightly different syntax. Perhaps I'm wrong, I
> certainly hope I'm wrong, but that's the impression I got from your
> comments on the python-ideas list.

    Actually it was circa 1964. Actually, it was precisely 1964 (I was 
there).

    No, I'm not advocating for dumb-down simplicity. Aristotle said that 
virtue is found at the mean. Either end of the spectrum is a problem 
(overly complicated, towards overly simplified) those end-points we must 
flee like the black plague. Normal people with reasonable training 
(college education) should be able to use python easily without 
confusion and without a computer science degree. Programming should be a 
liberal art available to everyone in the set of all "normal" educated 
people. Some developers (themselves perhaps with degrees Ph.D. in 
mathematics or computer science) forget about the fact that "normal" 
educated people want to leverage their computer (maybe with python) for 
problem solution without having to become a professional computer 
scientist. I am advocating for those people.

> You want to remove lambda because it causes confusion. Okay, for the sake
> of the argument I will agree that lambda is confusing. Do you know what
> else is confusing?

    I don't want to remove anything at this point. I am only suggesting 
that over time the python community might evaluate whether the lambda 
(map, filter, reduce) thing is a language benefit. If so, manet in 
aeternum.  Elif, deprecate it and over time phase it out completely. Its 
a community decision of course, and I'm NOT demanding anything.

> Threading is confusing. So is multiprocessing. So are databases. Unicode
> is confusing. First-class functions are confusing. Recursion is
> confusing. Closures are confusing. List comprehensions are confusing.
> What the hell are trampolines? I'm certainly confused by them.

    Argument by analogy almost never works. Please don't confuse my word 
"confusing" with your interpretation "complicated". Actually, I do not 
find any of those above mentioned as "confusing," while I do admit they 
are complicated--even extremely complicated. An intelligent person 
educated in the liberal arts should be able to sit down over time and 
pick-up the concepts in a new area--without--being confused by the 
material or presentation. Lambda is confusing NOT because its 
complicated (because its not) but because 1) it does not work like other 
lambda concepts in functional programming, and 2) because the syntax 
does not lend itself easily to immediate interpretation (by normal 
people) nor does it lend itself easily to explanation even in the best 
effort.

> If we remove lambda because it is confusing, shouldn't we also remove all
> these other confusing things? Where shall we stop?

    No.   see above.

> Should we stop only when Python is a confusion-free, utterly useless toy
> language? I don't think so. Or should we stop *before* going down that
> path? You want to single out lambda. I don't think we should.

    No.   see above.

> I didn't say that Python can be used as a functional language. I said you
> can write functional code in Python. And that is so obviously true that I
> cannot believe that you are disputing it.

    I'm not disputing that, not in the least. But advertising that 
python can be used to write functional code is misleading (particularly 
when lambda is included ;map,filter, reduce) because those who KNOW 
functional programming are going to be either 1) confused, or more 
likely, 2) disappointed.  Yes, I can make a nameless function 
(expression) and pass it to another function as an argument.  True 
enough, and powerful enough, but very confusing when the other aspects 
of functional programming with lambda do not hold precisely. Ok, 
functional with caveats.

>> In fact, I have gone out of my way to NOT use
>> lambda because I am fully aware that the BDFL hates it.
>
> In other words, you have had situations where you *could have* used
> lambda, perhaps even *should have* used lambda, but you intentionally
> went *out of your way* (i.e. made the job harder than it needed to be) to
> avoid it, just to slavishly ape the BDFL.

   No, no, no,  not at all. I went out-of-my-way to understand how inner 
functions could do everything lambda does. I use inner functions, not 
lambda, and everything works well; not to ape the BDFL, but because it 
does not appear that lambda is a stable concept, and because I want 
other people "in the normal" category to be able to support or at least 
read my code.

> Thank you for just proving my point for me. Your code would have been
> better, or at least easier, with lambda. Removing it would make the
> language worse, not better.

    No.   see above.

> lambda was designed to allow you to create anonymous functions
> in an expression, not as a statement. There is *no other way* to do that
> in Python.

    Yes, and I agree, and if that were *necessary* we wouldn't be having 
this conversation.  The point is that there is *no* reason that you must 
code your script that way.

> Would you like to discard def as well? No? Why not?

    I am not advocating discarding anything.  I am suggesting that 
lambda is not necessary and might be deprecated without too much 
trouble; if the community sees fit.  That is all.

    Since the name-space and arguably "def" itself is perhaps the most 
powerful aspect of python generally (extensibility) than of course the 
answer to your question is obvious, and discussing it would be silly.

    def is fine,   lambda not so much.  BUT I'm not demanding anyone 
discard it at the moment.  Try to remember Aristotle's mean.


marcus


From rosuav at gmail.com  Mon Mar 24 15:57:19 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 06:57:19 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <CALwzidk3qyeJvPZQ6CX_qmG00NNqhEwsb67WL_9eW1o9dHqdcw@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
 <53303b8a$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmqZ1ekiBEpGDtj-P_TVJ+=0R2CMVh4GOfCvL5vci=qm2g@mail.gmail.com>
 <CALwzidk3qyeJvPZQ6CX_qmG00NNqhEwsb67WL_9eW1o9dHqdcw@mail.gmail.com>
Message-ID: <CAPTjJmpdMcVsZhV0Q8bOs_ybzXSeMhNXoqP1ontvwT=HxbBpSA@mail.gmail.com>

On Tue, Mar 25, 2014 at 6:42 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Mon, Mar 24, 2014 at 1:12 PM, Chris Angelico <rosuav at gmail.com> wrote:
>> Incidentally, I've often modified my loop counter, in C or REXX or any
>> other language. About the only situation where I actually miss it in
>> Python, though, is iterating over a list and mutating the list on the
>> way through; and even that can often be done in other ways (maybe a
>> list comp, filtering out some of the elements?). It's amazing how
>> something can be so utterly fundamental (I mean, come ON! Who can
>> imagine a language with no equivalent of the basic "do i=1 to 10"
>> (REXX) or "for (int i=0;i<10;++i)" (C++) loop???) and yet so
>> dispensable.
>
> I'm not sure "fundamental" is the right word.  A for loop is just a
> while loop with some syntactic sugar.  For that matter, a while loop
> is just a structured goto...

Of course, and function calls are just stack operations and gotos too.
That's not what makes it fundamental - I'm talking at a source code
level. Can you imagine a high level language without a simple notation
for variable assignment? Certainly not. [1] Variable assignment, name
binding, whatever you call it, is fundamental. Some kind of structured
looping is also pretty critical; you don't see languages that force
you to use bare goto everywhere and call themselves "high level". [2]
Every high level language also needs some way to iterate over numbers.
Most of them provide it as an intrinsic; Python happens to do it as a
foreach over an easily-constructed iterable.

ChrisA

[1] DeScribe Macro Language would borderline-fail this test if I
called it a HLL. It has "SET something TO somevalue". But DML is about
on the level of Python's "dis.dis" output - assembly language for a
byte-code interpreter.
[2] DML passes this test, even. It has a block IF/ELSE/END IF
statement, and a REPEAT/END REPEAT for looping, with the loop
condition being provided by a statement "EXIT WHEN condition" that's
like Python's "if condition: break". Mind you, it also provides
language-level support for message boxes, including prompt boxes (ask
the user to provide a string or integer), so it's a bit of an odd
duck.


From newville at cars.uchicago.edu  Mon Mar 24 16:24:34 2014
From: newville at cars.uchicago.edu (Matt Newville)
Date: Mon, 24 Mar 2014 15:24:34 -0500
Subject: advice on sub-classing multiprocessing.Process and
 multiprocessing.BaseManager
Message-ID: <CA+7ESbr9i6VEO709jPF8ghoPRsUggqBrCEJhoXBn7LK6wYSA+w@mail.gmail.com>

I'm maintaining a python interface to a C library for a distributed
control system (EPICS, sort of a SCADA system) that does a large
amount of relatively light-weight network I/O.   In order to keep many
connections open and responsive, and to provide a simple interface,
the python library keeps a global store of connection state.

This works well for single processes and threads, but not so well for
multiprocessing, where the global state causes trouble.  The issue is
not too difficult to work around (ie, completely clear any such global
cache and insist that new connections be established in each process),
but easy to forget.

To make this easier, I have a function to clear the global cache,

def clear_my_cache():
     # empty global variables caching network connections
     return

and then subclass of multiprocessing.Process like:

class MyProcess(multiprocessing.Process):
    def __init__(self, **kws):
        multiprocessing.Process.__init__(self, **kws)

    def run(self):
        clear_my_cache()
        mp.Process.run(self)

This works fine.  I can subclass multiprocessing.pool.Pool too, as it
uses Process as a class variable (removing doc strings):

class Pool(object):
    Process = Process

    def __init__(self, processes=None, initializer=None, initargs=(),
                 maxtasksperchild=None):

and then uses self.Process in its Pool._repopulate_pool().  That makes
subclassing Pool is as easy as (removing doc strings):

class MyPool(multiprocssing.pool.Pool):
    def __init__(self, **kws):
        self.Process = MyProcess
        mp_pool.Pool.__init__(self, **kws)

I'm very pleased to need so little code here!  But, I run into trouble
when I try to subclass any of the Managers().  It looks like I would
have to make a nearly-identical copy of ~30 lines of
BaseManager.start() as it calls multiprocessing.Process() to create
processes there.   In addition, it looks like subclassing
multiprocessing.managers.SyncManager would mean making a
near-identical copy of a similar amount of code.

I'd be willing to do this, but it seems like a bad idea  -- I much
prefer overwriting self.Process as for Pool.

Does anyone have any advice for the best approach here?  Should, like
Pool,  BaseManager also use a class variable (Process = Process)?

Thanks in advance for any advice.

--Matt


From eneskristo at gmail.com  Mon Mar 24 16:30:18 2014
From: eneskristo at gmail.com (eneskristo at gmail.com)
Date: Mon, 24 Mar 2014 13:30:18 -0700 (PDT)
Subject: How to clear all content in a Tk()
Message-ID: <0ed94669-6c1e-4e2f-b79d-33bed8cdde15@googlegroups.com>

I have this program, and since I want to change stuff dynamically, I want to fully clear the root = Tk(), without deleting it. Is there a way to do so?


From gary.herron at islandtraining.com  Mon Mar 24 16:37:23 2014
From: gary.herron at islandtraining.com (Gary Herron)
Date: Mon, 24 Mar 2014 13:37:23 -0700
Subject: Memory error
In-Reply-To: <d4489c2b-6650-45b6-bcb0-7a1b648192d2@googlegroups.com>
References: <d4489c2b-6650-45b6-bcb0-7a1b648192d2@googlegroups.com>
Message-ID: <53309783.1090107@islandtraining.com>

On 03/24/2014 04:32 AM, Jamie Mitchell wrote:
> Hello all,
>
> I'm afraid I am new to all this so bear with me...
>
> I am looking to find the statistical significance between two large netCDF data sets.
>
> Firstly I've loaded the two files into python:
>
> swh=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/controlperiod/averages/swh_control_concat.nc', 'r')
>
> swh_2050s=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/2050s/averages/swh_2050s_concat.nc', 'r')
>
> I have then isolated the variables I want to perform the pearson correlation on:
>
> hs=swh.variables['hs']
>
> hs_2050s=swh_2050s.variables['hs']

This is not really a Python question.  It's a question about netCDF 
(whatever that may be), or perhaps it's interface to Python python-netCD4.

You may get an answer here, but you are far more likely to get one 
quickly and accurately from a forum dedicated to netCDF, or python-netCD.

Good luck.

Gary Herron


From victor.olex at vtenterprise.com  Mon Mar 24 16:57:49 2014
From: victor.olex at vtenterprise.com (victor.olex at vtenterprise.com)
Date: Mon, 24 Mar 2014 13:57:49 -0700 (PDT)
Subject: Python developer salary survey - results
Message-ID: <89759b83-95ac-4cb6-9597-bd64061b3c3e@googlegroups.com>

PyStreet's February salary survey attracted respondents from 37 countries. 

Median annual salary in the U.S.: $95,000
Median annual salary worldwide: $50,000

Complete study: http://bit.ly/1dgCw3p


From vincent at vincentdavis.net  Mon Mar 24 17:20:34 2014
From: vincent at vincentdavis.net (Vincent Davis)
Date: Mon, 24 Mar 2014 15:20:34 -0600
Subject: Merge/append CSV files with different headers
In-Reply-To: <CAPTjJmpmbQWxrSBmsyiYOvPbVJGwmzDoRv_8pQh+bZ9=8iQpsg@mail.gmail.com>
References: <CALyJZZWmAWP=STfZGpvN_NexxS=7DA9GrxOAC+2ibUNgkJtM1Q@mail.gmail.com>
 <CAPTjJmpmbQWxrSBmsyiYOvPbVJGwmzDoRv_8pQh+bZ9=8iQpsg@mail.gmail.com>
Message-ID: <CALyJZZXxCJ6Va2n2apwWWkCwwEVsSZKBzsMPWK++=EwgAypw9g@mail.gmail.com>

Thanks for the feedback.

Vincent Davis
720-301-3003


On Mon, Mar 24, 2014 at 1:44 PM, Chris Angelico <rosuav at gmail.com> wrote:

> On Tue, Mar 25, 2014 at 4:50 AM, Vincent Davis <vincent at vincentdavis.net>
> wrote:
> > I have several csv file I need to append (vertically). They have
> different
> > but overlapping headers. For example;
> > file1 headers ['a', 'b', 'c']
> > file2 headers ['d', 'e']
> > file3 headers ['c', 'd']
> >
> > Is there a better way than this
>
> Summary of your code:
>
> 1) Build up a set of all headers used, by opening each file and
> reading the headers.
> 2) Go through each file a second time and write them out.
>
> That seems like the best approach, broadly. You might be able to
> improve it a bit (it might be tidier to open each file once, but since
> you're using two different CSV readers, it'd probably not be), but by
> and large, I'd say you have the right technique. Your processing time
> here is going to be dominated by the actual work of copying.
>
> The only thing you might want to consider is order. The headers all
> have a set order to them, and it'd make sense to have the output come
> out as ['a', 'b', 'c', 'd', 'e'] - the first three from the first
> file, then adding in everything from subsequent files in the order
> they were found. Could be done easily enough by using 'in' and
> .append() on a list, rather than using a set. But if that doesn't
> matter to you, or if something simple like "sort the headers
> alphabetically" will do, then I think you basically have what you
> want.
>
> ChrisA
> --
> https://mail.python.org/mailman/listinfo/python-list
>
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From harrismh777 at gmail.com  Mon Mar 24 17:43:17 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 16:43:17 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
Message-ID: <lgq8th$nj4$1@speranza.aioe.org>

On 3/24/14 4:03 AM, Ian Kelly wrote:
>
> The difference does not really lie in the lambda construct per se but in
> the binding style of closures. Functional languages tend to go one way
> here; imperative languages tend to go the other. {snip}

> The result may be more surprising to users accustomed to functional
> languages, but I claim that it is *less* surprising to users of other
> imperative languages.

    Aside from the sin of spelling out "lambda,"
       should be   ( \x y -> x + y ) a b )  but, neither here nor there...

    Yes, its about closures, totally;  the most confusing aspect of 
lambda in python is not only the syntax but the idea of scope and 
closure (for that syntax).  Everyone is confused by this initially, not 
because its complicated, but because its confusing.  An example:

>>>>
>>>> adders= list(range(4))
>>>> adders
> [0, 1, 2, 3]
>>>> for n in adders:
> 	adders[n]=lambda a: a+n
>
> 	
>>>> print(adders[1](3))
> 6
>>>>

    The expected value as perceived by "normal" people is 4.

    This comes up on the list over and again year after year in various 
flavors, but always because lambda is unnecessarily confusing where it 
comes to how does it function; and by that we mean simply, how does 
scope and closure work in this context. Once the "normal" person is 
introduced to the scope and closure idiosyncrasies of pythons lambda, 
well then everything is much smoother. But how to fix?  Consider:

>>>>
>>>> adders= list(range(4))
>>>> adders
> [0, 1, 2, 3]
>>>> for n in adders:
> 	adders[n] = (lambda b: lambda a: b + a)(n)
>
> 	
>>>> adders[1](3)
> 4
>>>> adders[2](3)
> 5
>>>>

    Now, here is where I talk about confusion; explaining why the first 
lambda above does not work because of scope and closure, and then even 
worse, explaining why the second "double" lambda works in the lower 
example!

    Its a nightmare, really.

    And you are correct, its really about closure.

marcus





From marko at pacujo.net  Mon Mar 24 18:43:11 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 25 Mar 2014 00:43:11 +0200
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
Message-ID: <87ior3w740.fsf@elektro.pacujo.net>

Mark H Harris <harrismh777 at gmail.com>:

>    Yes, its about closures, totally;  the most confusing aspect of
> lambda in python is not only the syntax but the idea of scope and
> closure (for that syntax).  Everyone is confused by this initially, not
> because its complicated, but because its confusing.  An example:
>
>>>>> adders= list(range(4))
>>>>> for n in adders:
>> 	adders[n]=lambda a: a+n
>>>>> print(adders[1](3))
>> 6
>
>    The expected value as perceived by "normal" people is 4.

1. No, I don't think that understanding is automatically natural.

2. It does not concern Python only. For example, what does this scheme
   expression yield?

        ((let ((n 3))
           (let ((f (lambda () n)))
             (set! n 7)
             f)))

   Answer: 7

3. It doesn't concern lambda only. For example, rewrite your loop like
   this:

   for n in range(4):
       def add(a):
           return a + n
       adders[n] = add

   adders[1](3)
   => 6


Marko


From steve+comp.lang.python at pearwood.info  Mon Mar 24 18:58:19 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 24 Mar 2014 22:58:19 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8443.1395655163.18130.python-list@python.org>
 <lgpv85$rdq$1@speranza.aioe.org>
 <mailman.8460.1395688958.18130.python-list@python.org>
Message-ID: <5330b88b$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 06:22:28 +1100, Chris Angelico wrote:

> Aside: You'll often hear people talking about "map-reduce" with big
> data. Python supports that. Look!
> 
>>>> map.__reduce__
> <method '__reduce__' of 'map' objects>
> 
> Oh wait, that's nothing to do with reduce()...
> 
> *ducks for cover*

Ha ha, very funny :-P


http://code.activestate.com/recipes/577676-dirt-simple-mapreduce/




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Mon Mar 24 19:01:27 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 10:01:27 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lgq8th$nj4$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
Message-ID: <CAPTjJmqK6R+dGk9rzEmGZJJHUP8tLLPKNy36cvGJAjkkiqN3Vw@mail.gmail.com>

On Tue, Mar 25, 2014 at 8:43 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>>         adders[n] = (lambda b: lambda a: b + a)(n)
>
>    Now, here is where I talk about confusion; explaining why the first
> lambda above does not work because of scope and closure, and then even
> worse, explaining why the second "double" lambda works in the lower example!

Easy fix. Use the "explicit capture" notation:

adders[n] = lambda a, n=n: a+n

And there you are, out of your difficulty at once!

ChrisA


From rosuav at gmail.com  Mon Mar 24 19:07:01 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 10:07:01 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <5330b88b$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8443.1395655163.18130.python-list@python.org>
 <lgpv85$rdq$1@speranza.aioe.org>
 <mailman.8460.1395688958.18130.python-list@python.org>
 <5330b88b$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmrupwoBS=PogVi7TdRnVeuf6zfw0j_bP3vwBVXa_PWAmg@mail.gmail.com>

On Tue, Mar 25, 2014 at 9:58 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Tue, 25 Mar 2014 06:22:28 +1100, Chris Angelico wrote:
>
>> Aside: You'll often hear people talking about "map-reduce" with big
>> data. Python supports that. Look!
>>
>>>>> map.__reduce__
>> <method '__reduce__' of 'map' objects>
>>
>> Oh wait, that's nothing to do with reduce()...
>>
>> *ducks for cover*
>
> Ha ha, very funny :-P
>
>
> http://code.activestate.com/recipes/577676-dirt-simple-mapreduce/

That looks like a more serious map/reduce example. Mine came from a
double-take when I was looking at help(map) for some reason; there's a
__round__ magic method that helps define the round() function, there's
__abs__ for abs(), there's __str__ for str()... look, there's a
__reduce__ - it must be to help define reduce()! :)

ChrisA


From harrismh777 at gmail.com  Mon Mar 24 19:44:37 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 18:44:37 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8468.1395702091.18130.python-list@python.org>
Message-ID: <lgqg16$a2v$1@speranza.aioe.org>

On 3/24/14 6:01 PM, Chris Angelico wrote:

> Easy fix. Use the "explicit capture" notation:

> adders[n] = lambda a, n=n: a+n

> And there you are, out of your difficulty at once!

Yes, yes, yes,  and example:

 >>>> adders= list(range(4))
 >>>> for n in adders:
 >	adders[n] = lambda a, n=n: a+n
 >
 >	
 >>>> adders[1](3)
 >4
 >>>> adders[2](3)
 >5

    But, and this is the big (WHY?) is that necessary? In other words, 
its not about experts knowing how to make this work, its about "normal" 
people not understanding in the first place why its a problem, and why 
the various solutions work to fix it; even though "we" all know that 
nothing is 'broken'.

    And in reference to Marko's post, he's right, its not just python, 
but the issue is not where else is capture and scope a problem for 
confusion, the issue is whether python's lambda provides a significant 
opportunity for confusion that in the larger scheme of things (no pun 
intended) is not warranted.

marcus



From harrismh777 at gmail.com  Mon Mar 24 19:48:50 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 18:48:50 -0500
Subject: Reading in cooked mode (was Re: Python MSI not installing, log
 file showing name of a Viatnemese communist revolutionary)
References: <mailman.8409.1395538666.18130.python-list@python.org>
 <532f9a6b$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8433.1395631040.18130.python-list@python.org>
 <lgo9v1$b3i$1@speranza.aioe.org>
 <mailman.8470.1395703845.18130.python-list@python.org>
Message-ID: <lgqg92$a2v$2@speranza.aioe.org>

On 3/24/14 6:30 PM, Dennis Lee Bieber wrote:
> {And I recall standard practice was to hit \r, to return the carriage, \n
> for next line, and one RUBOUT to provide a delay while the carriage
> returned to the left<G>}

Yes, yes... I remember well, there had to be a delay (of some type) to 
wait for the horse and carriage to get from the right side of the field 
to the left.  Aaah, the good 'ol days.

marcus


From rosuav at gmail.com  Mon Mar 24 19:57:34 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 10:57:34 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lgqg16$a2v$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8468.1395702091.18130.python-list@python.org>
 <lgqg16$a2v$1@speranza.aioe.org>
Message-ID: <CAPTjJmoT_eJCx4hcMbK1WR1rUBkMZkhJ00mb_9Wgg7UvRRtsHw@mail.gmail.com>

On Tue, Mar 25, 2014 at 10:44 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/24/14 6:01 PM, Chris Angelico wrote:
>
>> Easy fix. Use the "explicit capture" notation:
>> adders[n] = lambda a, n=n: a+n
>> And there you are, out of your difficulty at once!
>    But, and this is the big (WHY?) is that necessary? In other words, its
> not about experts knowing how to make this work, its about "normal" people
> not understanding in the first place why its a problem, and why the various
> solutions work to fix it; even though "we" all know that nothing is
> 'broken'.

Why is it necessary? For the same reason that this works:

def func_pair():
    x = 0
    def inc():
        nonlocal x; x+=1
        return x
    def dec():
        nonlocal x; x-=1
        return x
    return inc, dec

fooup, foodn = func_pair()
barup, bardn = func_pair()
>>> fooup(), fooup(), fooup(), foodn()
(1, 2, 3, 2)
>>> barup(), barup(), bardn(), bardn()
(1, 2, 1, 0)

When you use the variable x in multiple places, it's the same variable
and it has a single value. If you don't want that, you have to make a
separate variable.

ChrisA


From ian.g.kelly at gmail.com  Mon Mar 24 19:58:11 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 24 Mar 2014 17:58:11 -0600
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lgq8th$nj4$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
Message-ID: <CALwzidm76LqqqEHTzzcENCzfjK05zsa5rS+ni7Z+uFO5S1o1sQ@mail.gmail.com>

On Mon, Mar 24, 2014 at 3:43 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/24/14 4:03 AM, Ian Kelly wrote:
>>
>>
>> The difference does not really lie in the lambda construct per se but in
>> the binding style of closures. Functional languages tend to go one way
>> here; imperative languages tend to go the other. {snip}
>
>
>> The result may be more surprising to users accustomed to functional
>> languages, but I claim that it is *less* surprising to users of other
>> imperative languages.
>
>
>    Aside from the sin of spelling out "lambda,"
>       should be   ( \x y -> x + y ) a b )  but, neither here nor there...

Well no, it *should* be ?x y . x + y but apparently some people don't
have that character on their keyboards, so it gets written as lambda
or \ instead.  Personally I dislike the \ style; it doesn't really
resemble a ? that closely, and to me the backslash denotes escape
sequences and set differences.  Nor is Python alone in spelling out
lambda: Scheme and Common Lisp spell it the same way. As far as I know
the \ for ? is unique to Haskell.


From harrismh777 at gmail.com  Mon Mar 24 19:56:23 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 18:56:23 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
Message-ID: <lgqgn7$bpd$1@speranza.aioe.org>

On 3/24/14 5:43 PM, Marko Rauhamaa wrote:
> Mark H Harris<harrismh777 at gmail.com>:

>>     Yes, its about closures, totally;  the most confusing aspect of
>> lambda in python is not only the syntax but the idea of scope and
>> closure (for that syntax).  Everyone is confused by this initially, not
>> because its complicated, but because its confusing.  An example:

>>>>>> adders= list(range(4))
>>>>>> for n in adders:
>>> 	adders[n]=lambda a: a+n
>>>>>> print(adders[1](3))
>>> 6

>>     The expected value as perceived by "normal" people is 4.
>
> 1. No, I don't think that understanding is automatically natural.

    It might not seem that way for an expert, but if you Google python 
lambda function closure(s)  you will notice that this is pretty much the 
natural way of interpreting things.

    Of course the problem is that the closure grabs the *last* number in 
the list which is used for each of the adder[] functions created. So, in 
other words, three (3) is the number added in each of the adder 
functions.  But here is the rub, it is not *ever* clear to people (even 
experienced python coders, me for instance) that this is how it should 
work. What is needed is the explicit closure "grab" recommended by 
ChrisA. But for the normal, that is just as bad (conceptually) because 
while it works it strays FAR away from expected lambda constructs known 
to functional programmers, and it is difficult to explain to non 
functional programmers... a proverbial catch 22.

marcus


From rosuav at gmail.com  Mon Mar 24 20:11:24 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 11:11:24 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lgqgn7$bpd$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
Message-ID: <CAPTjJmoN3rJeABuDiX5M-2gAsw646eccbuuEr6PfNcaFPBYCTw@mail.gmail.com>

On Tue, Mar 25, 2014 at 10:56 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> What is needed is the explicit closure "grab" recommended by ChrisA.

Which does work. You do know why, right?

ChrisA


From harrismh777 at gmail.com  Mon Mar 24 20:16:15 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 19:16:15 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8473.1395706293.18130.python-list@python.org>
Message-ID: <lgqhsf$ehi$1@speranza.aioe.org>

On 3/24/14 7:11 PM, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 10:56 AM, Mark H Harris<harrismh777 at gmail.com>  wrote:
>> What is needed is the explicit closure "grab" recommended by ChrisA.
>
> Which does work. You do know why, right?

Sure.  ... but again, that's not the point. The point is NOT can you 
explain why it works, the point is that as a lambda construct it is NOT 
clear why it works, and because the construct does not match what lambda 
users might expect (naturally) there are *constant* questions about it.

So, again, I'll restate that the community might consider (over time) 
whether the confusion created by lambda in python is worth the time and 
trouble to maintain the construct in the language. Is the value add 
worth the cost of confusion. I don't think so; others are bound to disagree.

marcus


From rosuav at gmail.com  Mon Mar 24 20:19:56 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 11:19:56 +1100
Subject: advice on sub-classing multiprocessing.Process and
 multiprocessing.BaseManager
In-Reply-To: <CA+7ESbr9i6VEO709jPF8ghoPRsUggqBrCEJhoXBn7LK6wYSA+w@mail.gmail.com>
References: <CA+7ESbr9i6VEO709jPF8ghoPRsUggqBrCEJhoXBn7LK6wYSA+w@mail.gmail.com>
Message-ID: <CAPTjJmoYBC9T5-ZbyaSX_m19JcXa5Lw0cSzXEAcfn-NZrO+V6g@mail.gmail.com>

On Tue, Mar 25, 2014 at 7:24 AM, Matt Newville
<newville at cars.uchicago.edu> wrote:
> I'm maintaining a python interface to a C library for a distributed
> control system (EPICS, sort of a SCADA system) that does a large
> amount of relatively light-weight network I/O.   In order to keep many
> connections open and responsive, and to provide a simple interface,
> the python library keeps a global store of connection state.
>
> This works well for single processes and threads, but not so well for
> multiprocessing, where the global state causes trouble.

>From the sound of things, a single process is probably what you want
here. Is there something you can't handle with one process?

ChrisA


From rosuav at gmail.com  Mon Mar 24 20:28:40 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 11:28:40 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lgqhsf$ehi$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8473.1395706293.18130.python-list@python.org>
 <lgqhsf$ehi$1@speranza.aioe.org>
Message-ID: <CAPTjJmouZXC0x6UjyTsA+FokwLqWFWZXkYcONvSH9Rf4+9Vj_A@mail.gmail.com>

On Tue, Mar 25, 2014 at 11:16 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/24/14 7:11 PM, Chris Angelico wrote:
>>
>> On Tue, Mar 25, 2014 at 10:56 AM, Mark H Harris<harrismh777 at gmail.com>
>> wrote:
>>>
>>> What is needed is the explicit closure "grab" recommended by ChrisA.
>>
>>
>> Which does work. You do know why, right?
>
>
> Sure.  ... but again, that's not the point. The point is NOT can you explain
> why it works, the point is that as a lambda construct it is NOT clear why it
> works, and because the construct does not match what lambda users might
> expect (naturally) there are *constant* questions about it.
>
> So, again, I'll restate that the community might consider (over time)
> whether the confusion created by lambda in python is worth the time and
> trouble to maintain the construct in the language. Is the value add worth
> the cost of confusion. I don't think so; others are bound to disagree.

Pure functional programming, from what I understand, doesn't *have*
variables other than function arguments. So the way to implement "x =
1" is to call a subfunction with an argument of 1, which is referred
to as x. (Am I right so far?) In that case, the default argument trick
is exactly the right way to implement that in Python.

ChrisA


From breamoreboy at yahoo.co.uk  Mon Mar 24 20:32:01 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 25 Mar 2014 00:32:01 +0000
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <lgqhsf$ehi$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8473.1395706293.18130.python-list@python.org>
 <lgqhsf$ehi$1@speranza.aioe.org>
Message-ID: <lgqipr$e0u$1@ger.gmane.org>

On 25/03/2014 00:16, Mark H Harris wrote:
> On 3/24/14 7:11 PM, Chris Angelico wrote:
>> On Tue, Mar 25, 2014 at 10:56 AM, Mark H
>> Harris<harrismh777 at gmail.com>  wrote:
>>> What is needed is the explicit closure "grab" recommended by ChrisA.
>>
>> Which does work. You do know why, right?
>
> Sure.  ... but again, that's not the point. The point is NOT can you
> explain why it works, the point is that as a lambda construct it is NOT
> clear why it works, and because the construct does not match what lambda
> users might expect (naturally) there are *constant* questions about it.
>
> So, again, I'll restate that the community might consider (over time)
> whether the confusion created by lambda in python is worth the time and
> trouble to maintain the construct in the language. Is the value add
> worth the cost of confusion. I don't think so; others are bound to
> disagree.
>
> marcus

I'd vote to have lambda taken out of the language if it meant avoiding 
tedious threads like this one :(

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From harrismh777 at gmail.com  Mon Mar 24 20:50:10 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 19:50:10 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
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Message-ID: <lgqjs2$i5m$1@speranza.aioe.org>

On 3/24/14 7:32 PM, Mark Lawrence wrote:
>> marcus
>
> I'd vote to have lambda taken out of the language if it meant avoiding
> tedious threads like this one :(
>

Dude, you remind me of Eeyore;   "days, weeks, months,  who knows..."

Its just a conversation.  Don't setup a polling booth yet.  Its all in 
fun and science.

marcus


From tjreedy at udel.edu  Mon Mar 24 21:04:41 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 24 Mar 2014 21:04:41 -0400
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <CAPTjJmrupwoBS=PogVi7TdRnVeuf6zfw0j_bP3vwBVXa_PWAmg@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
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Message-ID: <lgqkn4$jmf$2@ger.gmane.org>

On 3/24/2014 7:07 PM, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 9:58 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> On Tue, 25 Mar 2014 06:22:28 +1100, Chris Angelico wrote:
>>
>>> Aside: You'll often hear people talking about "map-reduce" with big
>>> data. Python supports that. Look!
>>>
>>>>>> map.__reduce__
>>> <method '__reduce__' of 'map' objects>
>>>
>>> Oh wait, that's nothing to do with reduce()...
>>>
>>> *ducks for cover*
>>
>> Ha ha, very funny :-P
>>
>>
>> http://code.activestate.com/recipes/577676-dirt-simple-mapreduce/
>
> That looks like a more serious map/reduce example. Mine came from a
> double-take when I was looking at help(map) for some reason; there's a
> __round__ magic method that helps define the round() function, there's
> __abs__ for abs(), there's __str__ for str()... look, there's a
> __reduce__ - it must be to help define reduce()! :)

That was my first think also. I believe __pickle__ or __unpickle__ would 
have been more appropriate.

-- 
Terry Jan Reedy



From tjreedy at udel.edu  Mon Mar 24 21:20:48 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 24 Mar 2014 21:20:48 -0400
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <lgqgn7$bpd$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
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Message-ID: <lgqllb$mta$1@ger.gmane.org>

On 3/24/2014 7:56 PM, Mark H Harris wrote:

>     Of course the problem is that the closure

A function is not a closure unless defined within another function. In 
the examples I remember, there was no nesting.

 > grabs the *last* number in
> the list which is used for each of the adder[] functions created.

Wrong. Functions look up global and nonlocal names, such as n, when the 
function is called.

 >>> adders = list(range(4))
 >>> for n in adders: adders[n] = lambda a: a+n

 >>> n = 1000
 >>> adders[1](3)
1003

Same result if the function *is* a closure, making n nonlocal rather 
than global.

def f():
     adders = list(range(4))
     for n in adders: adders[n] = lambda a: a+n
     n = 1000
     return adders

print(f()[1](3))
 >>>
1003

The only definition time grabbing is with default arg expressions.

This discussion is a bit funny in a way. Some people are puzzled that 
default arg expressions 'grab' just once, as definition time, rather 
than with each call. Others (I hope others) are puzzled that body 
expressions 'grab' with each call, rather than just once, at definition 
time. That seems to be particularly true when the body is in a lambda 
expression rather than a def statement.

-- 
Terry Jan Reedy



From nispray at gmail.com  Mon Mar 24 21:26:58 2014
From: nispray at gmail.com (Wesley)
Date: Mon, 24 Mar 2014 18:26:58 -0700 (PDT)
Subject: Python developer salary survey - results
In-Reply-To: <89759b83-95ac-4cb6-9597-bd64061b3c3e@googlegroups.com>
References: <89759b83-95ac-4cb6-9597-bd64061b3c3e@googlegroups.com>
Message-ID: <6ecc1d94-d27f-4fad-a7b8-0f26a12cca90@googlegroups.com>

? 2014?3?25????UTC+8??4?57?49??victo... at vtenterprise.com???
> PyStreet's February salary survey attracted respondents from 37 countries. 
> 
> 
> 
> Median annual salary in the U.S.: $95,000
> 
> Median annual salary worldwide: $50,000
> 
> 
> 
> Complete study: http://bit.ly/1dgCw3p

I am below the worldwide median...


From tjreedy at udel.edu  Mon Mar 24 21:31:46 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 24 Mar 2014 21:31:46 -0400
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <CAPTjJmouZXC0x6UjyTsA+FokwLqWFWZXkYcONvSH9Rf4+9Vj_A@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
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Message-ID: <lgqm9t$obv$1@ger.gmane.org>

On 3/24/2014 8:28 PM, Chris Angelico wrote:

> Pure functional programming, from what I understand, doesn't *have*
> variables other than function arguments.

function *parameters*, if in the 'variable = name' camp

> So the way to implement "x = 1" is to call a subfunction

with a parameter named 'x'

> with an argument of 1

Funny, I was just thinking about that last night. I really learned it 
when trying to translate python code to the scheme dialect racket.

import math as m

s = m.sqrt(2)
a = m.sin(s) + m.cos(s)
del s # to be exactly equivalent to the below, but not needed

b = (lambda x: m.sin(x) + m.cos(x))(m.sqrt(2))

print(a,b)
 >>>
1.14370964075811 1.14370964075811


-- 
Terry Jan Reedy



From rosuav at gmail.com  Mon Mar 24 21:41:32 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 12:41:32 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lgqm9t$obv$1@ger.gmane.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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Message-ID: <CAPTjJmoT5GDatxWDqvi27iP-tFYPDe99EQMrtm8koJZNsPVY+A@mail.gmail.com>

On Tue, Mar 25, 2014 at 12:31 PM, Terry Reedy <tjreedy at udel.edu> wrote:
> On 3/24/2014 8:28 PM, Chris Angelico wrote:
>
>> Pure functional programming, from what I understand, doesn't *have*
>> variables other than function arguments.
>
>
> function *parameters*, if in the 'variable = name' camp
>
>
>> So the way to implement "x = 1" is to call a subfunction
>
>
> with a parameter named 'x'
>
>> with an argument of 1

Ah, yes, parameter. I tend to use the terms interchangeably, but they
do have formal definitions and distinctions. But otherwise, yes;
that's how I was seeing that.

ChrisA


From steve+comp.lang.python at pearwood.info  Mon Mar 24 21:45:02 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 01:45:02 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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Message-ID: <5330df9e$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Mon, 24 Mar 2014 14:47:11 -0500, Mark H Harris wrote:

> On 3/24/14 4:49 AM, Steven D'Aprano wrote:
>> There's no doubt that lambda is less-often useful than is the def
>> statement. But not only is it still useful, but there is a continual
>> stream of people asking for Python to make it *more useful* by allowing
>> the body of a lambda to be a full block, not just a single statement.
>> Guido has stated (although I cannot remember where, so cannot paste a
>> link) that he accepts that in principle, so long as somebody comes up
>> with acceptable syntax.
> 
>     Now, this will seem strange to you, but if lambda were expanded to
> include an entire block, well now, I would know two things:
>    1) python has commitment to lambda

Python has a commitment to lambda. lambda is not going anywhere. There 
was some idea chatter five or six years ago about dropping it from the 
language. It didn't get dropped, so now it is as much a part of the 
language as for-loops, print, classes and import.


>    and 2) lambda would become WAY more useful...

Every one agrees that being able to include a full suite of statements in 
an expression form would be useful. Unfortunately, due to the constraint 
of Python's syntax, it seems to be impossible. People have looked for 20+ 
years, and nobody has come up with an acceptable syntax.


[...]
>>> Lambda is a problem of confusion for scientists and other
>>> mathematicians (amateur and otherwise) {snip}
>>{snip}
>> But nor should the confusion of somebody who doesn't know the language
>> count for much.
> 
>     This is the main disagreement between the two of us on this topic.
> It should count for TONS; whole metric TONs. Because someone who
> understands python primarily, and after five years of coding (say me)
> somebody tells (me) to use lambda in a key clause so that my sort will
> work, or work better, or work "their" way; and I have no idea why I need
> this nameless function (after I find out that "that" is what it is!)

Then you don't understand *sorting*. If you don't understand why you need 
a key function, the problem is not the syntax used to create the key 
function, but your understanding of sort. Time to remove sorting from 
Python, yes? No?

It's not lambda that is giving you trouble. That's just syntax. There is 
no conceptual difference between:

    data.sort(key=lambda item: *magic goes on here*)

and

    def key_func(item):
        *magic goes on here*

    data.sort(key=key_func)


If the first confuses you, so will the second. If you are capable of 
learning what the first means, learning the second is no harder.


> Its confusing, and please contrast between complicated. I don't mind
> complicated, or extensive, or even hard, but when something is
> needlessly confusing, then why?

I don't know why you insist it is confusing. Maybe you're just no good at 
seeing the correspondence between 

    lambda x: expression

and

    def func(x):
        return expression


>> Python's ints don't work exactly the same as ints do in some other
>> languages, nor do Python's strings, nor is Python's object model
>> precisely the same as that of some other languages. I think that it
>> would be a ridiculous idea to discard int, str and the entire object
>> system just because some people are surprised that Python doesn't
>> behave exactly like some other language. I don't think lambda is any
>> different.
> 
>     Your logic is faulty here.  Conceptually python's lambda doesn't
> work as expected, from contexts that define lambda

Python defines lambda too. Why should Python have to bend over to suit 
the definition used by other languages? They don't own the concept of 
anonymous functions. Anonymous functions are found in all sorts of 
languages, with different semantics and different syntax:

Pike:  lambda(typ1 para1, typ2, para2, ...) { ... };
Perl:  sub { my ($a, $b) = @_; ... }
Smalltalk:  [:a :b| ... ]
Haskell:  \a b -> ...
Erlang: fun(a, b) -> ... end
Dylan: method(a, b) ... end method


to mention just a few. Ruby even has at least three ways of spelling 
lambda, one of which even uses the word lambda:

    {|a, b| ... } 
    lambda {|a, b| ...}
    proc {|a, b| ...}


> and where lambda in functional programming is VERY important.

And? Nobody is saying that they have to stop using the term lambda. 
Certainly I'm not. I wouldn't be so rude.


> For one thing, why would we
> want to "spell out" the word "lambda".    ( \x y -> x + y ) a b ) If
> we're going to use lambda, then use it.

So you don't like the syntax of Python's lambda. That's your prerogative. 
But frankly, one thing I dislike about Haskell is that it is too terse. 
Why would you use lambda without spelling out explicitly that you are 
doing so?


>> Other languages -- not even Lisp -- don't get to be the sole decider as
>> to what counts as an anonymous function. Python's lambda may be
>> limited, but it is a perfectly fine lambda for what it is intended to
>> do.
> 
>     Is that the same as George W. Bush's "decider" ?

I have no idea why you are mocking my use of the word "decider". It's a 
perfectly legitimate word, a standard term in English for someone who 
decides. The Oxford dictionary dates it back to sometime between 1670 and 
1699, so it is hardly a neologism or one of Junior Bush's malapropisms.

Let me put it another way. Functional programming languages do not get to 
be the sole decision-maker of what counts as a legitimate syntax or 
semantics for anonymous functions.


>     I agree, and so does the link I referenced, for what it was designed
> to do, its powerful; esp if one needs to embed a function in an
> expression;  that is what lambda is for.

Right.

 
>>> Its also confusing to sophisticated users of all stripes who may not
>>> be aware of "lambda" at all.
>>
>> If they're not aware of lambda, how are they confused by it?
> 
>     See above.  They are recommended its use (maybe on this list) and
> they just don't get it; because its unnecessarily confusing.

Then they are aware of lambda.

Confusing in what way? Is it the keyword used? You don't need to know the 
background of the term to learn to use it. If non-English speakers can 
memorise that you use "class" to define classes, English speakers can 
stop being so precious and memorise that "lambda" is used to define a 
function in an expression.

'lambda' is just one of those jargon words, like 'tuple', 'iterate', 
'boolean', 'closure', ... just learn it, and you'll be fine. If you want 
to investigate the background of the word, go right ahead, but it won't 
make you a better programmer to know that "boolean" is named after George 
Boole, and I still have no idea what the origin of "tuple" is. (And after 
15+ years I still want to spell it "turple".)


[...]
> Programming should be a
> liberal art available to everyone in the set of all "normal" educated
> people. 

Why should it be? Programming is no more a liberal art than painting is 
an offshoot of calculus.

Most "normal" (normal as defined by whom?) educated people have no 
interest, no desire, and no aptitude for programming. Most *programmers* 
have no aptitude for the rigor of programming -- the world is full of 
lousy programmers churning out their 40 lines of buggy VB/PHP/Java/C code 
per day but aren't any good at it:

http://www.yacoset.com/Home/signs-that-you-re-a-bad-programmer
http://haacked.com/archive/2007/02/27/Why_Cant_Programmers._Read.aspx/

Programming is a skill, like writing iambic pentameter. Should liberal 
arts courses ban the use of iambic pentameter by poets because some 
people find it confusing and can't count syllables or tell the difference 
between stressed and unstressed? (I know I can't. My wife despairs that I 
am so useless at anything like poetry.)


> Some developers (themselves perhaps with degrees Ph.D. in
> mathematics or computer science) forget about the fact that "normal"
> educated people want to leverage their computer (maybe with python) for
> problem solution without having to become a professional computer
> scientist. I am advocating for those people.

So you say. But I think you are actually being terribly condescending and 
elitist at the same time. Consider:

(1) People who just want to get the job done, without learning a bunch of 
theory, *won't care* how their sort key function is written. They're 
looking for a recipe that they can copy and paste, and whether you write 
it like this:

    data.sort(key=lambda item: item[1])

or like this:

    from operator import itemgetter
    data.sort(key=itemgetter(1))

or like this:

    def sort_key(item):
        return item[1]
    data.sort(key=sort_key)


*they won't care*. In fact, they'll probably prefer the first version, 
with lambda, because it is fewer lines to copy.

And this is okay. Sometimes you've got more important things to do than 
understand how every line of your code works, especially for throw-away 
code, you just want to use it. It is very elitist to insist that features 
that some people don't understand have to go. Do you understand how 
import works? I bet you don't. It's so complicated that there are 
probably only one or two core developers who really understand it in all 
it's glory. You just use it: "import this", and it just works. lambda is 
the same.

Sometimes programming is just a means to an end and the programmer just 
wants an answer now.


(2) You're concluding that just because somebody is confused by lambda, 
they would be better off if lambda was removed. That's horribly 
patronising. Have you considered that maybe they will take that as an 
opportunity to *learn something new*? That they'll learn how to use 
lambda, they may even investigate the theory behind it?

I am especially aggravated by your attack on lambda because I was that 
person. I had never heard of lambda calculus. When I first learned 
Python, lambda's syntax troubled me for a while. I had to keep looking it 
up, until suddenly the penny dropped that the argument list is exactly 
the same as the argument list of def. Replace "def name" with "lambda", 
drop the brackets, and use a single expression without "return", and 
Joan's your Auntie.

But I learned it, and it got me interested in where the name came from, 
and I discovered the lambda calculus and decided that while I have every 
admiration for the people who fly that high into the rarefied air of 
theory, that's not an area I have much interest in. In any case, I am a 
better programmer -- or at least a more educated one -- precisely because 
Python didn't dumb down, it didn't patronise me, it offered an 
"advanced" (huh! not really) feature that I otherwise would never have 
been exposed to.

Yes, Python could remove lambda, and take that opportunity away from 
others. Python would be a lesser language for it, and Python programmers 
will be lesser programmers for it.

Python programmers are some of most widely read programmers around, 
compared to the average C or PHP or VB coder. That's because they are 
exposed to so many different concepts in the language. Not everyone cares 
to learn about them, and that's okay, but they aren't Python's core 
audience.


>> You want to remove lambda because it causes confusion. Okay, for the
>> sake of the argument I will agree that lambda is confusing. Do you know
>> what else is confusing?
> 
>     I don't want to remove anything at this point. I am only suggesting
> that over time the python community might evaluate whether the lambda
> (map, filter, reduce) thing is a language benefit. If so, manet in
> aeternum.  Elif, deprecate it and over time phase it out completely. Its
> a community decision of course, and I'm NOT demanding anything.

This discussion was held five years ago. And lambda is still here.


>> Threading is confusing. So is multiprocessing. So are databases.
>> Unicode is confusing. First-class functions are confusing. Recursion is
>> confusing. Closures are confusing. List comprehensions are confusing.
>> What the hell are trampolines? I'm certainly confused by them.
> 
>     Argument by analogy almost never works. Please don't confuse my word
> "confusing" with your interpretation "complicated". Actually, I do not
> find any of those above mentioned as "confusing," 

Good for you! I mean it, I'm not being sarcastic. But I *know* people 
find all those things confusing, because (1) either I found, or still do, 
find them confusing, or (2) because I've seen people confused by them. 
When I say "confusing", I mean it. I don't mean complicated.


> while I do admit they
> are complicated--even extremely complicated. An intelligent person
> educated in the liberal arts should be able to sit down over time and
> pick-up the concepts in a new area--without--being confused by the
> material or presentation. Lambda is confusing NOT because its
> complicated (because its not) but because 1) it does not work like other
> lambda concepts in functional programming, 

Do you really believe that people educated in the liberal arts are 
exposed to the lambda calculus? Most MATHEMATICIANS aren't exposed to 
lambda calculus.


> and 2) because the syntax
> does not lend itself easily to immediate interpretation (by normal
> people) nor does it lend itself easily to explanation even in the best
> effort.

I think that's just nonsense. Take a one-line function:

    def func(args):
        return stuff

Remove the "def func", the brackets, and the "return". Move it all to one 
line, and stick the magic word "lambda" at the front:

    lambda args: stuff


And you're done. That's all there is to it.

Your insistence that lambda is confusing is awfully condescending. People 
are not as dumb as you insist, and they are perfectly capable of learning 
lambda without a comp sci degree. Like any technical jargon, there is 
vocabulary and meaning to learn, but the concept is no more difficult 
than ordinary def functions.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From harrismh777 at gmail.com  Mon Mar 24 21:56:28 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 20:56:28 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <8aa0b833-e7b7-485b-8258-c59eebdace93@googlegroups.com>
Message-ID: <lgqnoc$p9e$1@speranza.aioe.org>

On 3/22/14 3:59 PM, vasudevram wrote:
>
> Thanks to all those who answered.
>
> - Vasudev

I am wondering if the question was answered?


>>>>
>>>> x = [[1,2],[3,4],[5,6]]
>>>> import ast
>>>> ast.dump(ast.parse('[x for x in x for x in x]'))
 >
> "Module(body=
 >
> [Expr(value=ListComp(elt=Name(id='x', ctx=Load()),
 >
> generators=
 >
> [comprehension(target=Name(id='x', ctx=Store()), iter=Name(id='x', ctx=Load()), ifs=[]),
 >
> comprehension(target=Name(id='x', ctx=Store()), iter=Name(id='x', ctx=Load()), ifs=[])]))])"
>>>>

This is really, I think, the answer to the OPs question. Knowing how 
python is parsing the comprehension of comprehensions is important, yes?

Obviously each x is within a different scope, within a separate 
iterator. This seems to unwind from right to left?

I didn't see any ast entries in the thread, so just wondering.

marcus




From breamoreboy at yahoo.co.uk  Mon Mar 24 22:06:53 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 25 Mar 2014 02:06:53 +0000
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <5330df9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <532fffaf$0$29878$c3e8da3$5496439d@news.astraweb.com>
 <lgq23s$44k$1@speranza.aioe.org>
 <5330df9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgqobn$u4k$1@ger.gmane.org>

On 25/03/2014 01:45, Steven D'Aprano wrote:
>
> (1) People who just want to get the job done, without learning a bunch of
> theory, *won't care* how their sort key function is written. They're
> looking for a recipe that they can copy and paste, and whether you write
> it like this:
>
>      data.sort(key=lambda item: item[1])
>
> or like this:
>
>      from operator import itemgetter
>      data.sort(key=itemgetter(1))
>
> or like this:
>
>      def sort_key(item):
>          return item[1]
>      data.sort(key=sort_key)
>
>
> *they won't care*. In fact, they'll probably prefer the first version,
> with lambda, because it is fewer lines to copy.
>

I'm firmly in this camp, practicality beats purity and all that.  I've 
used the first and second versions shown above as they happened to be in 
the recipes I was aquiring, I wouldn't contemplate the third.  That's 
just my mindset, which is what I love about Python, by pure luck it fits 
me like made to measure clothing.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From rosuav at gmail.com  Mon Mar 24 22:17:51 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 13:17:51 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <5330df9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <532fffaf$0$29878$c3e8da3$5496439d@news.astraweb.com>
 <lgq23s$44k$1@speranza.aioe.org>
 <5330df9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmq+UT+8=VAXEKT-Oqf+Z2rtET3DhTz5Nh+LXLq1D6W3qQ@mail.gmail.com>

On Tue, Mar 25, 2014 at 12:45 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Programming is a skill, like writing iambic pentameter. Should liberal
> arts courses ban the use of iambic pentameter by poets because some
> people find it confusing and can't count syllables or tell the difference
> between stressed and unstressed? (I know I can't. My wife despairs that I
> am so useless at anything like poetry.)

Iambic pentameter is hard. I know, I tried writing eight lines of it
for my brother's wedding. (Okay, I was writing *acrostic* iambic
pentameter, putting his wife's new surname down the left edge of the
page, but still, it's pretty restrictive.) It's much more fun, I
reckon, to write paragraphs of text roughly eighty characters across.
Prosaic, I know....

ChrisA


From harrismh777 at gmail.com  Mon Mar 24 22:39:33 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 21:39:33 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
Message-ID: <lgqq99$v5j$1@speranza.aioe.org>

On 3/24/14 8:20 PM, Terry Reedy wrote:
> On 3/24/2014 7:56 PM, Mark H Harris wrote:

>> the list which is used for each of the adder[] functions created.
>
> Wrong. Functions look up global and nonlocal names, such as n, when the
> function is called.
>

hi Terry, yeah, I know; this is what's *wrong* all at once.

Functions "look up global and nonlocal names" such as n, is semantics 
for "each created function 'grabs' the last number (n) in the list", 
well, because that (n) is bound at call-time to (3).

Your version semantically is detailed and correct; my version 
semantically is "how it is perceived" by the user, which is also 
correct. Again, how the function gets the n (grab or lookup) is mute. 
The user is often confused about how this happens. As you have shown, 
even experts in this field disagree about how this is described, which 
is also my secondary point--- the whole thing is VERY difficult to 
explain to "normal" users. It often takes several sessions and goes on 
and on, until Mark Lawrence calls it tedious.

marcus


From rustompmody at gmail.com  Mon Mar 24 23:00:56 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 20:00:56 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python language
 feature?)
In-Reply-To: <mailman.8472.1395705541.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
Message-ID: <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>

On Tuesday, March 25, 2014 5:28:11 AM UTC+5:30, Ian wrote:
> On Mon, Mar 24, 2014 at 3:43 PM, Mark H Harris wrote:
> > On 3/24/14 4:03 AM, Ian Kelly wrote:
> >> The difference does not really lie in the lambda construct per se but in
> >> the binding style of closures. Functional languages tend to go one way
> >> here; imperative languages tend to go the other. {snip}
> >> The result may be more surprising to users accustomed to functional
> >> languages, but I claim that it is *less* surprising to users of other
> >> imperative languages.
> >    Aside from the sin of spelling out "lambda,"
> >       should be   ( \x y -> x + y ) a b )  but, neither here nor there...

> Well no, it *should* be ?x y . x + y but apparently some people don't
> have that character on their keyboards, so it gets written as lambda
> or \ instead.  Personally I dislike the \ style; it doesn't really
> resemble a ? that closely, and to me the backslash denotes escape
> sequences and set differences.  Nor is Python alone in spelling out
> lambda: Scheme and Common Lisp spell it the same way. As far as I know
> the \ for ? is unique to Haskell.

Yeah: Its 2014 (at least out here)...
About time we started using unicode in earnest dont you think??

Id like to see the following spellings corrected:
lambda to ?
in to ?
(preferably with the 'in' predicate and the 'in' in 'for' disambiguated)
set([]) to ?

And some parentheses disambiguation
Internal ambiguity: Is '(...)' a paren? a function? a tuple?
External ambiguity: {} in python vs in set theory

[And now I hand it over to our very dear resident troll to explain the glories
of the FSR]


From rosuav at gmail.com  Mon Mar 24 23:17:35 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 14:17:35 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
Message-ID: <CAPTjJmq16kFTGbAB-hS41kxHAyQzu11tK3vP_8N67odp2p8u1Q@mail.gmail.com>

On Tue, Mar 25, 2014 at 2:00 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> Yeah: Its 2014 (at least out here)...
> About time we started using unicode in earnest dont you think??

We do.

> Id like to see the following spellings corrected:
> lambda to ?
> in to ?
> (preferably with the 'in' predicate and the 'in' in 'for' disambiguated)
> set([]) to ?

The problems with these is not Unicode or a lack thereof, but keys. I
know how to type "lambda" on any keyboard I reach for; if it's a
full-sized QWERTY variant, I can type it without looking, and if it's
something else then I can peer at the thing and find the appropriate
five letters. (Phone keyboards are notoriously peer-worthy.) How do I
type ?? Do I have to memorize an alt-key sequence? Do I need to keep a
set of "language keywords" in a file somewhere so I can copy and
paste? Does my editor have to provide them?

What is really gained by using the short-hand? It becomes nigh
ungoogleable; yes, you can paste ? into Google and find out that it's
called lambda (and, if Python used that as a keyword, you could type
"? python" into Google and get to the docs), but how do you figure out
which part of this to search for?

sockets.sort(key=?data:data[1])

More likely you'd search for "sockets" or "sort" or maybe "key" or
"data", but you wouldn't expect to search for the symbol.

> And some parentheses disambiguation
> Internal ambiguity: Is '(...)' a paren? a function? a tuple?
> External ambiguity: {} in python vs in set theory

I don't know about the difference between {} in set theory and Python,
but the multiple uses of () actually boil down to two:

1) Grouping, which includes tuples; there's a special case whereby
grouping nothing makes a zero-item tuple, but everything else is just
the comma

2) Functions (both definition and call)

Disambiguating them might be of some small value, but since they're
the same in pretty much every language under the sun, it would feel
like syntactic salt: you have to use a different, and hard to type,
form of parenthesis for one (or even both!) of what ought to just be
simple brackets.

And what's the benefit? Shorter code, maybe. A few 2-6 letter
sequences that can become single characters. I can sympathize somewhat
with the set issue (because {} means an empty dict), although set() is
better than set([]); having a short form for that would be of some
advantage. But not if it's hard to type.

ChrisA


From harrismh777 at gmail.com  Mon Mar 24 23:15:05 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 22:15:05 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
Message-ID: <lgqsbp$4ur$1@speranza.aioe.org>

On 3/24/14 10:00 PM, Rustom Mody wrote:
> About time we started using unicode in earnest dont you think??
>
> Id like to see the following spellings corrected:
> lambda to ?

    great idea!

{snip}
>
> [And now I hand it over to our very dear resident troll to explain the glories
> of the FSR]

Now, that's not at all patronizing, ~is it?


!vdrt

marcus      :)





From harrismh777 at gmail.com  Mon Mar 24 23:25:28 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 22:25:28 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
Message-ID: <lgqsv8$6e9$1@speranza.aioe.org>

On 3/24/14 10:17 PM, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 2:00 PM, Rustom Mody<rustompmody at gmail.com>  wrote:
>> Yeah: Its 2014 (at least out here)...
>> About time we started using unicode in earnest dont you think??
>
> We do.
>
>> Id like to see the following spellings corrected:
>> lambda to ?
>> in to ?
>> (preferably with the 'in' predicate and the 'in' in 'for' disambiguated)
>> set([]) to ?
>
> The problems with these is not Unicode or a lack thereof, but keys. I
> know how to type "lambda" on any keyboard I reach for;

Yeah, its a fit.  I found pi -> ?

... and here's apple pi ->   ??

but, rats, can't find \ lambda


From matt.newville at gmail.com  Mon Mar 24 23:27:41 2014
From: matt.newville at gmail.com (matt.newville at gmail.com)
Date: Mon, 24 Mar 2014 20:27:41 -0700 (PDT)
Subject: advice on sub-classing multiprocessing.Process and
 multiprocessing.BaseManager
In-Reply-To: <mailman.8474.1395707125.18130.python-list@python.org>
References: <CA+7ESbr9i6VEO709jPF8ghoPRsUggqBrCEJhoXBn7LK6wYSA+w@mail.gmail.com>
 <mailman.8474.1395707125.18130.python-list@python.org>
Message-ID: <80cf8fb7-d0c5-43a9-bc6f-c61ce6214f98@googlegroups.com>

On Monday, March 24, 2014 7:19:56 PM UTC-5, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 7:24 AM, Matt Newville
> 
> > I'm maintaining a python interface to a C library for a distributed
> > control system (EPICS, sort of a SCADA system) that does a large
> > amount of relatively light-weight network I/O.   In order to keep many
> > connections open and responsive, and to provide a simple interface,
> > the python library keeps a global store of connection state.
> >
> > This works well for single processes and threads, but not so well for
> > multiprocessing, where the global state causes trouble.
> 
> 
> From the sound of things, a single process is probably what you want
> here. Is there something you can't handle with one process?

Thanks for the reply.  I find that appreciation is greatly (perhaps infinitely) delayed whenever I reply "X is probably not what you want to do" without further explanation to a question of "can I get some advice on how to do X?". So, I do thank you for your willingness to reply, even such a guaranteed-to-be-under-appreciated reply. 

There are indeed operations that can't be handled with a single process, such as simultaneously using multiple cores.  This is why we want to use multiprocessing instead of (or, in addition to) threading.  We're trying to do real-time collection of scientific data from a variety of data sources, generally within a LAN. The data can get largish and fast, and intermediate processing occasionally requires non-trivial computation time.  So being able to launch worker processes that can run independently on separate cores would be very helpful.  Ideally, we'd like to let sub-processes make calls to the control system too, say, read new data.

I wasn't really asking "is multiprocessing appropriate?" but whether there was a cleaner way to subclass multiprocessing.BaseManager() to use a subclass of Process().  I can believe the answer is No, but thought I'd ask.

Thanks again,

--Matt


From harrismh777 at gmail.com  Mon Mar 24 23:28:55 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 22:28:55 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <lgqsv8$6e9$1@speranza.aioe.org>
Message-ID: <lgqt5n$6pq$1@speranza.aioe.org>

On 3/24/14 10:25 PM, Mark H Harris wrote:
>
> but, rats, can't find \ lambda


Ok, there we go ->   ?


and  ?  and  ?   and  ?



no problem.



From roy at panix.com  Mon Mar 24 23:29:19 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 24 Mar 2014 23:29:19 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
Message-ID: <roy-66D138.23291924032014@news.panix.com>

In article <mailman.8483.1395717465.18130.python-list at python.org>,
 Chris Angelico <rosuav at gmail.com> wrote:

> On Tue, Mar 25, 2014 at 2:00 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> > Yeah: Its 2014 (at least out here)...
> > About time we started using unicode in earnest dont you think??
> 
> We do.
> 
> > Id like to see the following spellings corrected:
> > lambda to ??
> > in to ???
> > (preferably with the 'in' predicate and the 'in' in 'for' disambiguated)
> > set([]) to ?
> 
> The problems with these is not Unicode or a lack thereof, but keys. I
> know how to type "lambda" on any keyboard I reach for; if it's a
> full-sized QWERTY variant, I can type it without looking, and if it's
> something else then I can peer at the thing and find the appropriate
> five letters. (Phone keyboards are notoriously peer-worthy.) How do I
> type ??? Do I have to memorize an alt-key sequence? Do I need to keep a
> set of "language keywords" in a file somewhere so I can copy and
> paste? Does my editor have to provide them?

I started programming on 029 keypunches and ASR-33 teletypes.  If you asked me to
type most of the punctuation we take for granted today (not to mention lower case
letters), I would have looked at you as if you had asked me to type something in greek.

Hardware evolves.  I assume that future generations of programmers will have input
devices better suited to unicode than the clumsy keyboards we use today.


From rosuav at gmail.com  Mon Mar 24 23:44:46 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 14:44:46 +1100
Subject: advice on sub-classing multiprocessing.Process and
 multiprocessing.BaseManager
In-Reply-To: <80cf8fb7-d0c5-43a9-bc6f-c61ce6214f98@googlegroups.com>
References: <CA+7ESbr9i6VEO709jPF8ghoPRsUggqBrCEJhoXBn7LK6wYSA+w@mail.gmail.com>
 <mailman.8474.1395707125.18130.python-list@python.org>
 <80cf8fb7-d0c5-43a9-bc6f-c61ce6214f98@googlegroups.com>
Message-ID: <CAPTjJmr6LJNworUcQmhu_pbHJ6o84WGHihueXzAfZ5X-0z62Aw@mail.gmail.com>

On Tue, Mar 25, 2014 at 2:27 PM,  <matt.newville at gmail.com> wrote:
> Thanks for the reply.  I find that appreciation is greatly (perhaps infinitely) delayed whenever I reply "X is probably not what you want to do" without further explanation to a question of "can I get some advice on how to do X?". So, I do thank you for your willingness to reply, even such a guaranteed-to-be-under-appreciated reply.
>

Heh. I do see that side of it, but the problem is that sometimes a
question will be asked that implies a completely wrong approach. Take
this example:

"I'm having trouble passing a global variable to a function, how can I do it?"

This exact question came up recently (I may have the wording wrong),
and some of the solutions offered were horrendously convoluted messes
involving passing the name of a global to the function which then used
'exec' or 'eval'. While technically that answers the question, it's
much more helpful to take a step back - no, let's take a step forward
- now another step back - and we're cha-cha'ing! - well, unless you're
a real genius, just take the step back, and look at what you're
actually trying to achieve.

I wasn't trying to imply that you absolutely ought to use a single
process, but more that the exact reasons for not using one process are
significant in your style of coding the multi-process method.

> There are indeed operations that can't be handled with a single process, such as simultaneously using multiple cores.  This is why we want to use multiprocessing instead of (or, in addition to) threading.  We're trying to do real-time collection of scientific data from a variety of data sources, generally within a LAN. The data can get largish and fast, and intermediate processing occasionally requires non-trivial computation time.  So being able to launch worker processes that can run independently on separate cores would be very helpful.  Ideally, we'd like to let sub-processes make calls to the control system too, say, read new data.
>
> I wasn't really asking "is multiprocessing appropriate?" but whether there was a cleaner way to subclass multiprocessing.BaseManager() to use a subclass of Process().  I can believe the answer is No, but thought I'd ask.
>

I've never subclassed BaseManager like this. It might be simpler to
spin off one or more workers and not have them do any network
communication at all; that way, you don't need to worry about the
cache. Set up a process tree with one at the top doing only networking
and process management (so it's always fast), and then use a
multiprocessing.Queue or somesuch to pass info to a subprocess and
back. Then your global connection state is all stored within the top
process, and none of the others need care about it. You might have a
bit of extra effort to pass info back to the parent rather than simply
writing it to the connection, but that's a common requirement in other
areas (eg GUI handling - it's common to push all GUI manipulation onto
the main thread), so it's a common enough model.

But if subclassing and tweaking is the easiest way, and if you don't
mind your solution being potentially fragile (which subclassing like
that is), then you could look into monkey-patching Process. Inject
your code into it and then use the original. It's not perfect, but it
may turn out easier than the "subclass everything" technique.

ChrisA


From rustompmody at gmail.com  Mon Mar 24 23:43:43 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 20:43:43 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8483.1395717465.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
Message-ID: <a434e0d3-b2e1-400d-a9a2-ac35493c2c4a@googlegroups.com>

On Tuesday, March 25, 2014 8:47:35 AM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 2:00 PM, Rustom Mody wrote:
> > Yeah: Its 2014 (at least out here)...
> > About time we started using unicode in earnest dont you think??

> We do.

> > Id like to see the following spellings corrected:
> > lambda to ?
> > in to ?
> > (preferably with the 'in' predicate and the 'in' in 'for' disambiguated)
> > set([]) to ?

> The problems with these is not Unicode or a lack thereof, but keys. I
> know how to type "lambda" on any keyboard I reach for; if it's a
> full-sized QWERTY variant, I can type it without looking, and if it's
> something else then I can peer at the thing and find the appropriate
> five letters. (Phone keyboards are notoriously peer-worthy.) How do I
> type ?? Do I have to memorize an alt-key sequence? Do I need to keep a
> set of "language keywords" in a file somewhere so I can copy and
> paste? Does my editor have to provide them?

> What is really gained by using the short-hand? It becomes nigh
> ungoogleable; yes, you can paste ? into Google and find out that it's
> called lambda (and, if Python used that as a keyword, you could type
> "? python" into Google and get to the docs), but how do you figure out
> which part of this to search for?

> sockets.sort(key=?data:data[1])

> More likely you'd search for "sockets" or "sort" or maybe "key" or
> "data", but you wouldn't expect to search for the symbol.

> > And some parentheses disambiguation
> > Internal ambiguity: Is '(...)' a paren? a function? a tuple?
> > External ambiguity: {} in python vs in set theory

> I don't know about the difference between {} in set theory and Python,
> but the multiple uses of () actually boil down to two:

> 1) Grouping, which includes tuples; there's a special case whereby
> grouping nothing makes a zero-item tuple, but everything else is just
> the comma

> 2) Functions (both definition and call)

> Disambiguating them might be of some small value, but since they're
> the same in pretty much every language under the sun, it would feel
> like syntactic salt: you have to use a different, and hard to type,
> form of parenthesis for one (or even both!) of what ought to just be
> simple brackets.

> And what's the benefit? Shorter code, maybe. A few 2-6 letter
> sequences that can become single characters. I can sympathize somewhat
> with the set issue (because {} means an empty dict), although set() is
> better than set([]); having a short form for that would be of some
> advantage. But not if it's hard to type.

> ChrisA

Of all your objections, the 'google-able' one is the most hard-hitting.
Yes its important and I have no answers.

What you are missing is that programmers spend
90% of their time reading code
10% writing code

You may well be in the super-whiz category (not being sarcastic here)
All that will change is upto 70-30. (ecause you rarely make a mistake)
You still have to read oodles of others' code

I find python (as haskell) sweet because they dont force me read
parsing-drudgery like '{}'.
Given that a compiler can parse whitespace (python), or '{}' (C) in microseconds
whereas I take seconds, this is really terrible economics

Increasing the lexical variety of the code is in the same direction
[There is no need implied that overdoing it and becoming APL is good :-) ]


From rustompmody at gmail.com  Mon Mar 24 23:44:51 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 20:44:51 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8483.1395717465.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
Message-ID: <3605803d-ec90-4484-8a3f-37d06d0b1207@googlegroups.com>

On Tuesday, March 25, 2014 12:28:16 AM UTC+5:30, Mark H. Harris wrote:
> On 3/24/14 4:58 AM, Mark Lawrence wrote:
> > Where do you get reduce from if it's not in the standard library?

>     That was "a" proposal for 3000. Its there, but its not on the 
> built-ins; ie., you have to import it.  The confusion: why reduce, why 
> not filter, nor map?  {rhetorical}

> > As for lambda I've no real interest in it, other than when copying examples
> > where it's used to (say) provide a key function.

> This is one of my main points to Steven. In my experience "most" people 
> do not intend to use lambda for anything; they are trying to sort this 
> or that and don't quite know how to get the key right and some helpful 
> somebody gives them a key=lambda yadda yadda .  They use it, and it 
> works, but they are scratching their head saying to themselves, "what it 
> that, how does it work, how can I understand it and on and on".

Your example backfires more than you perhaps realize
1. Most people who-have-not-heard-of (WHNHO) generators dont intend to use
generators. Somebody shows then a couple of uses and they then find them
useful in other contexts
2. Most programmers coming from C where vararg exists but is really
much too painful to use outside of printf, dont want to use default
arguments. Somebody shows them default arguments then they find nifty uses
for the same
3. Most people WHNHO special methods ...
4. Most people WHNHO slices ...

Just sayin...

> That is what we mean by confusing. Or another really great example is 
> this thread. Somebody asks about a language feature and somebody else 
> helpfully answers the question by providing them with a similar lambda!!

I am not in pro or anti lambda camp.
My grouses are 3, all re comprehensions

1. Technical: I consider the comprehension binding rules wrong -- not lambda
2. Methodological: Experienced people showing comprehensions
as 'nothing more than' a short-form for a for-loop are being less helpful
to the noob than they know.
3. Pedagogical: Comprehensions are hard, for loops are easy.

To convey comprehensions two contrasting perspectives are needed:
1. The for-loop view
2. The set-theory view

Give only one, and misunderstandings and confusions proliferate
Yes 'only one' can be either one. In the haskell world the pedagogical error
tends to be the opposite to the one out here:
Noobs write: [... x in l, y in m,...]
and wonder why the efficiency is vastly different from
[... y in m, x in l, ...]

Comes from emphasising the declarative (set-theory) view too much, the
imperative (for-loop) view too little


From harrismh777 at gmail.com  Mon Mar 24 23:48:04 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 22:48:04 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <532fffaf$0$29878$c3e8da3$5496439d@news.astraweb.com>
 <lgq23s$44k$1@speranza.aioe.org>
 <5330df9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgqu9j$9l1$1@speranza.aioe.org>

On 3/24/14 8:45 PM, Steven D'Aprano wrote:

> Your insistence that lambda is confusing is awfully condescending. People
> are not as dumb as you insist, and they are perfectly capable of learning
> lambda without a comp sci degree. Like any technical jargon, there is
> vocabulary and meaning to learn, but the concept is no more difficult
> than ordinary def functions.

This is an Ad Hominem. My opinion that lambda is confusing must not be 
construed to mean condescension; not coming from my pen.

I do not insist that people are dumb, nor do I insist that people cannot 
learn python without a comp sci degree. Pushing those words into my 
mouth and then beating me up for saying them is, well, ad hominem.

What I am insisting is that *many* people, as point of fact, are 
confused by the python lambda construct particularly when it is embedded 
within a   for x in   and the lambda is supposed to capture the value x 
(as in my previous examples). This say nothing of their intelligence and 
says nothing about my supposed motive of condescension. (we my judge 
actions, but not motives)

I am advocating for understanding, among all python users--- novice and 
expert alike. Especially when I find so many experts who want to "know" 
(like the OP on this thread) and other experts who (like ecumenical 
councils) cannot agree (also noticed on this thread).

I am not seeking over simplification, and I am not seeking to limit the 
expert in any way;  just advocating for Aristotle's mean, whereat we 
find virtue.

marcus




From rosuav at gmail.com  Mon Mar 24 23:51:00 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 14:51:00 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <roy-66D138.23291924032014@news.panix.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
Message-ID: <CAPTjJmoJngPV0Az1azNSY63q6GV3pH=e1gZNM86JFBo-ZWW__g@mail.gmail.com>

On Tue, Mar 25, 2014 at 2:29 PM, Roy Smith <roy at panix.com> wrote:
> I started programming on 029 keypunches and ASR-33 teletypes.  If you asked me to
> type most of the punctuation we take for granted today (not to mention lower case
> letters), I would have looked at you as if you had asked me to type something in greek.
>
> Hardware evolves.  I assume that future generations of programmers will have input
> devices better suited to unicode than the clumsy keyboards we use today.

And there you have a circular problem. Until the bulk of programmers
have access to such keyboards, programming languages shouldn't use
such symbols (because most of their users won't be able to type them);
and until programming languages make use of those symbols, there's
little reason to put them on keyboards.

Supporting both may look tempting, but you effectively create two ways
of spelling the exact same thing; it'd be like C's trigraphs. Do you
know what ??= is, without looking it up? [1]

ChrisA

[1] I will accept "An obfuscation tool" as a correct answer here.


From rosuav at gmail.com  Mon Mar 24 23:57:02 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 14:57:02 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <a434e0d3-b2e1-400d-a9a2-ac35493c2c4a@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
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Message-ID: <CAPTjJmoCtjxhSScnhboEUsj_u_rX7hhhv4Cd1UGBFpT-gXXEsA@mail.gmail.com>

On Tue, Mar 25, 2014 at 2:43 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> What you are missing is that programmers spend
> 90% of their time reading code
> 10% writing code
>
> You may well be in the super-whiz category (not being sarcastic here)
> All that will change is upto 70-30. (ecause you rarely make a mistake)
> You still have to read oodles of others' code

No, I'm not missing that. But the human brain is a tokenizer, just as
Python is. Once you know what a token means, you comprehend it as that
token, and it takes up space in your mind as a single unit. There's
not a lot of readability difference between a one-symbol token and a
one-word token. Also, since the human brain works largely with words,
you're usually going to grok things based on how you would read them
aloud:

x = y + 1

eggs equals why plus one

They take up roughly the same amount of storage space. One of them,
being a more compact notation, lends itself well to a superstructure
of notation; compare:

x += 1

eggs plus-equals one

inc eggs

You can eyeball the first version and read it as the third, which is a
space saving in your brain. But it's not fundamentally different from
the second. So the saving from using a one-letter symbol that's read
"lambda" rather than the actual word "lambda" is extremely minimal.
Unless you can use it in a higher-level construct, which seems
unlikely in Python (maybe it's different in Haskell? Maybe you use
lambda more and actually do have those supernotations?), you won't
really gain anything.

ChrisA


From rustompmody at gmail.com  Mon Mar 24 23:56:19 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 20:56:19 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8483.1395717465.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
Message-ID: <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>

On Tuesday, March 25, 2014 8:47:35 AM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 2:00 PM, Rustom Mody wrote:
> > Yeah: Its 2014 (at least out here)...
> > About time we started using unicode in earnest dont you think??

> We do.

> > Id like to see the following spellings corrected:
> > lambda to ?
> > in to ?
> > (preferably with the 'in' predicate and the 'in' in 'for' disambiguated)
> > set([]) to ?

> The problems with these is not Unicode or a lack thereof, but keys. I
> know how to type "lambda" on any keyboard I reach for; if it's a
> full-sized QWERTY variant, I can type it without looking, and if it's
> something else then I can peer at the thing and find the appropriate
> five letters. (Phone keyboards are notoriously peer-worthy.) How do I
> type ?? Do I have to memorize an alt-key sequence? Do I need to keep a
> set of "language keywords" in a file somewhere so I can copy and
> paste? Does my editor have to provide them?

> What is really gained by using the short-hand? It becomes nigh
> ungoogleable; yes, you can paste ? into Google and find out that it's
> called lambda (and, if Python used that as a keyword, you could type
> "? python" into Google and get to the docs), but how do you figure out
> which part of this to search for?

> sockets.sort(key=?data:data[1])

> More likely you'd search for "sockets" or "sort" or maybe "key" or
> "data", but you wouldn't expect to search for the symbol.

> > And some parentheses disambiguation
> > Internal ambiguity: Is '(...)' a paren? a function? a tuple?
> > External ambiguity: {} in python vs in set theory

> I don't know about the difference between {} in set theory and Python,
> but the multiple uses of () actually boil down to two:

In set theory {} makes sets
In python {} makes dictionaries

> 1) Grouping, which includes tuples; there's a special case whereby
> grouping nothing makes a zero-item tuple, but everything else is just
> the comma

> 2) Functions (both definition and call)

> Disambiguating them might be of some small value, but since they're
> the same in pretty much every language under the sun, it would feel

What 'they'?? I dont get: If you are talking of disambiguating function definition and call -- yeah thats overkill

If you are talking of overlap between tuples parentheses and function (call)
well consider
f(x,y) vs f((x,y)) vs (x,y) vs ((x,y))
Paren vs tuples: why do we need to write (x,) not (x)

All this is because () is doing triple-duty


From harrismh777 at gmail.com  Mon Mar 24 23:59:57 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 24 Mar 2014 22:59:57 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
Message-ID: <lgquvt$b7t$1@speranza.aioe.org>

On 3/24/14 10:51 PM, Chris Angelico wrote:
> Supporting both may look tempting, but you effectively create two ways
> of spelling the exact same thing; it'd be like C's trigraphs. Do you
> know what ??= is,

This was a fit for me, back in the day IBM (system36 & system38). When 
we started supporting the C compiler (ha!) and non of our 5250 terminals 
could provide the C punctuation we take for granted today--- so we 
invented tri-graphs for { and } and others. It was a hoot.

I personally think the answer is extended key maps triggered by meta 
keys shift ctrl opt alt command |  which call up full alternate mappings 
of Greek|Latin|Math|symbols &c which can be chosen by mouse|pointing 
device.


The mac calls these keyboard viewer, and character viewer. In that way 
the full unicode set can be available from a standard qwerty keyboard 
without modifying the hardware right away.

marcus


From rustompmody at gmail.com  Tue Mar 25 00:08:29 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 21:08:29 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <lgquvt$b7t$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
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 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
Message-ID: <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>

On Tuesday, March 25, 2014 9:29:57 AM UTC+5:30, Mark H. Harris wrote:
> On 3/24/14 10:51 PM, Chris Angelico wrote:
> > Supporting both may look tempting, but you effectively create two ways
> > of spelling the exact same thing; it'd be like C's trigraphs. Do you
> > know what ??= is,

> This was a fit for me, back in the day IBM (system36 & system38). When 
> we started supporting the C compiler (ha!) and non of our 5250 terminals 
> could provide the C punctuation we take for granted today--- so we 
> invented tri-graphs for { and } and others. It was a hoot.

> I personally think the answer is extended key maps triggered by meta 
> keys shift ctrl opt alt command |  which call up full alternate mappings 
> of Greek|Latin|Math|symbols &c which can be chosen by mouse|pointing 
> device.

> The mac calls these keyboard viewer, and character viewer. In that way 
> the full unicode set can be available from a standard qwerty keyboard 
> without modifying the hardware right away.

I think Roy is right in saying that what looks unrealistic with one
technology looks natural with another (out phones are already handling
speech and handwriting)

And Chris is right in (rephrasing) we may have unicode-happy OSes and
languages. We cant reasonably have unicode-happy keyboards.
[What would a million-key keyboard look like? Lets leave the cost aside...]

Problem is that unicode deals with very different sides:
Universality of the math language
Locality of the zillions of human languages

If any character could be a variable, distinguishing the different things that
look like 'A' would be a nightmare


From rosuav at gmail.com  Tue Mar 25 00:14:30 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 15:14:30 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org>
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 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
Message-ID: <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>

On Tue, Mar 25, 2014 at 2:56 PM, Rustom Mody <rustompmody at gmail.com
>> I don't know about the difference between {} in set theory and Python,
>> but the multiple uses of () actually boil down to two:
>
> In set theory {} makes sets
> In python {} makes dictionaries

That's a backward-compatibility issue. Braces in Python meant a
dictionary before it acquired a set type (at least, so I learned in
history class - I wasn't using Python back then), so empty braces have
to continue to mean empty dictionary. I sympathize with the confusion,
but short of confusing everyone terribly by changing dicts to use
something other than braces (maybe borrow Pike's mapping notation, ([
])??), I don't really see a solution.

>> 1) Grouping, which includes tuples; there's a special case whereby
>> grouping nothing makes a zero-item tuple, but everything else is just
>> the comma
>
>> 2) Functions (both definition and call)
>
>> Disambiguating them might be of some small value, but since they're
>> the same in pretty much every language under the sun, it would feel
>
> What 'they'?? I dont get: If you are talking of disambiguating function definition and call -- yeah thats overkill

No no. Disambiguating grouping and fuction definition/call. There's no
reason to have definition and call of functions differ.

> If you are talking of overlap between tuples parentheses and function (call)
> well consider
> f(x,y) vs f((x,y)) vs (x,y) vs ((x,y))
> Paren vs tuples: why do we need to write (x,) not (x)
>
> All this is because () is doing triple-duty

Tuples don't use parentheses. You only confuse yourself when you
insist on that. The only case with parens that actually makes a tuple
is the special empty tuple; imagine if that were given a name instead,
like "Empty". That would solve that confusion.

There's another minorly special case, and that's that the trailing
comma is mandatory on a one-item tuple. In all others, it's optional,
but the one-item tuple would be ambiguous otherwise.

>>> len((1,2,3,))
3
>>> len((1,2,))
2
>>> len((1,))
1

(By the way, bringing in another discussion: The comma isn't part of
the element, nor is it exactly a separator, nor is it exactly a
terminator. Just like a newline in a text file.)

So the only ambiguity is between function calls and grouping. Tuples
are just part of grouping, in that you need to disambiguate a
one-tuple-arg function call from a multiple-arg function call - as in
the above len() calls. And that's where I think it would be highly
confusing to mandate something different. Suppose we used $( )$ for
function calls, and ^( )^ for grouping:

x = ^(1 + 2)^ * 3
y = range$(x)$

What have we gained by distinguishing them? Not a lot. If an open
parenthesis immediately follows another token, it's calling that
previous token; if it follows an operator, it's grouping. Seems pretty
simple to me.

(Cue the spate of emails pointing out something I've missed that
breaks that rule, in which case call it a rule of thumb.)

ChrisA


From rosuav at gmail.com  Tue Mar 25 00:19:50 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 15:19:50 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <lgquvt$b7t$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
Message-ID: <CAPTjJmovAedK_4ph1suaYdJryKvkAxcAW=QhjWUSpMjyNZ342g@mail.gmail.com>

On Tue, Mar 25, 2014 at 2:59 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> I personally think the answer is extended key maps triggered by meta keys
> shift ctrl opt alt command |  which call up full alternate mappings of
> Greek|Latin|Math|symbols &c which can be chosen by mouse|pointing device.
>
>
> The mac calls these keyboard viewer, and character viewer. In that way the
> full unicode set can be available from a standard qwerty keyboard without
> modifying the hardware right away.

I can get up a character map on any platform fairly easily, and if
not, I can always Google the name of the character I want and copy and
paste from fileformat.info or some other handy site. It's not that
hard. But if I want to say "copyright", it's still quicker for me to
type nine letters than to hunt down U+00A9 ? to paste in somewhere.
Even more so with lambda, which is a shorter word and a less common
symbol (having an easy way to type A9 isn't uncommon these days, but
not many give an easy way to type U+03BB). I'm much more comfortable
typing that out.

ChrisA


From rosuav at gmail.com  Tue Mar 25 00:29:48 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 15:29:48 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <lgoh7j$otg$1@speranza.aioe.org>
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 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
Message-ID: <CAPTjJmopOfH+9YQuMb9ZaKNg_OMxKwG4hN3ymBV86Y5EzSYQEg@mail.gmail.com>

On Tue, Mar 25, 2014 at 3:08 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> And Chris is right in (rephrasing) we may have unicode-happy OSes and
> languages. We cant reasonably have unicode-happy keyboards.
> [What would a million-key keyboard look like? Lets leave the cost aside...]

Actually, it wouldn't be that bad. Unicode allows for only 1114112
characters (thanks to UTF-16), of which only the first three planes
have any actual characters on them (so, a maximum of about 200K
characters). All you'd need would be a system that organizes them
(using their hex codepoints isn't exactly useful), and you could type
any character with a maximum of, say, 6-8 keystrokes; Huffman coded,
of course, so the average would be 1.5 keystrokes per character
actually used. Add one meta key: Charset. Hold that and press L and
you get (say) ?, U+03BB; Charset+Shift+L is ?, U+039B. Ctrl+Charset+L
might give you a Cyrillic ? (U+043B), and Ctrl+Charset+Shift+L would
then be ? (U+041B), the upper-case version of that.

Emacs users would love it.

ChrisA


From rustompmody at gmail.com  Tue Mar 25 01:00:23 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 22:00:23 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8489.1395721791.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
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Message-ID: <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>

On Tuesday, March 25, 2014 9:59:48 AM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 3:08 PM, Rustom Mody  wrote:
> > And Chris is right in (rephrasing) we may have unicode-happy OSes and
> > languages. We cant reasonably have unicode-happy keyboards.
> > [What would a million-key keyboard look like? Lets leave the cost aside...]

> Actually, it wouldn't be that bad. Unicode allows for only 1114112
> characters (thanks to UTF-16), of which only the first three planes
> have any actual characters on them (so, a maximum of about 200K
> characters). All you'd need would be a system that organizes them
> (using their hex codepoints isn't exactly useful), and you could type
> any character with a maximum of, say, 6-8 keystrokes; Huffman coded,
> of course, so the average would be 1.5 keystrokes per character
> actually used. Add one meta key: Charset. Hold that and press L and
> you get (say) ?, U+03BB; Charset+Shift+L is ?, U+039B. Ctrl+Charset+L
> might give you a Cyrillic ? (U+043B), and Ctrl+Charset+Shift+L would
> then be ? (U+041B), the upper-case version of that.

> Emacs users would love it.

Its already there -- and even easier
Switch to cyrillic-jis-russian (whatever that is!)
and I get ? from k ? from K

Full layout

     +----------------------------------------------------------------+
      |? ?|? ?|? ?|? ? |? ?|? ?|? ?|? ?|? ?|? ?| ? ?|? ?| ? ? |
     +----------------------------------------------------------------+
        | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? |
       +------------------------------------------------------------+
         | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? |? ?|
        +-----------------------------------------------------------+
           | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? | ? ? |? ?|
          +-------------------------------------------------+
		    +-----------------------------+
		    |          space bar          |
		    +-----------------------------+


The catch is in the claim to huffman coding
Huffman coding requires a statistical distribution
Whose shall we take

And now the discussion is political not technical


From rosuav at gmail.com  Tue Mar 25 01:08:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 16:08:43 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <roy-66D138.23291924032014@news.panix.com>
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 <lgquvt$b7t$1@speranza.aioe.org>
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Message-ID: <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>

On Tue, Mar 25, 2014 at 4:00 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> Its already there -- and even easier
> Switch to cyrillic-jis-russian (whatever that is!)
> and I get ? from k ? from K

How quickly can you switch, type one letter (to generate one Cyrillic
character), and switch back? If you can do that more quickly than
typing a word, then (for you!) it might be worth using those letters
as symbols.

ChrisA


From harrismh777 at gmail.com  Tue Mar 25 01:14:42 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 00:14:42 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
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 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
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 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
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Message-ID: <lgr3c1$k9l$1@speranza.aioe.org>

On 3/25/14 12:08 AM, Chris Angelico wrote:

> How quickly can you switch, type one letter (to generate one Cyrillic
> character), and switch back?

... very fast.

Is not this nicer?

 >>> ? = pi
 >>>
 >>> sin(?/4)
0.7071067811865475
 >>>
 >>> cos(?/4)
0.7071067811865476
 >>>

    my pdeclib constants extension will have alternate spellings for ? 
and ? and ? and others...

    But what if python had a math symbols extension so that universal 
mathematics could be written the way we do it on a black|board, er, I 
mean white|board?

marcus



From rustompmody at gmail.com  Tue Mar 25 01:23:26 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 22:23:26 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <lgr3c1$k9l$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
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 <roy-66D138.23291924032014@news.panix.com>
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 <lgr3c1$k9l$1@speranza.aioe.org>
Message-ID: <4576875e-29cf-42b4-ac8d-2f75fadebe20@googlegroups.com>

On Tuesday, March 25, 2014 10:38:43 AM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 4:00 PM, Rustom Mody wrote:
> > Its already there -- and even easier
> > Switch to cyrillic-jis-russian (whatever that is!)
> > and I get ? from k ? from K

> How quickly can you switch, type one letter (to generate one Cyrillic
> character), and switch back? If you can do that more quickly than
> typing a word, then (for you!) it might be worth using those letters
> as symbols.

Well Russian is Greek to me (or more correctly Russian!)
So Ive no clue about ergonomics

So let me talk of which input methods I use -- devanagari and tex.
I have devanagari-itrans set up in emacs as default (other) input method
So Ctrl-\ (ie 1? keystrokes) puts emacs into devanagari mode

For tex Ive to type the keystroke for invoking
'set-input-method'
then spell out the input method (there seem to be hundreds)
RET

Considering that I use tex much more than devanagari I guess I should 
switch the default to tex


From rosuav at gmail.com  Tue Mar 25 01:27:33 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 16:27:33 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <lgr3c1$k9l$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
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 <lgquvt$b7t$1@speranza.aioe.org>
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Message-ID: <CAPTjJmrsK2tc_7BFhGzdYhZV=-t6s_29CStyyekO4BicJ_9nYg@mail.gmail.com>

On Tue, Mar 25, 2014 at 4:14 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/25/14 12:08 AM, Chris Angelico wrote:
>
>> How quickly can you switch, type one letter (to generate one Cyrillic
>> character), and switch back?
>
>
> ... very fast.
>
> Is not this nicer?
>
>>>> ? = pi
>>>>
>>>> sin(?/4)
> 0.7071067811865475
>>>>
>>>> cos(?/4)
> 0.7071067811865476
>>>>
>
>    my pdeclib constants extension will have alternate spellings for ? and ?
> and ? and others...

That's good! (Although typing ? quicker than pi is majorly pushing it.
I can type pi with two keystrokes. But for longer keywords, that's the
way it needs to be.) You can be at the front of the curve - using
non-ASCII symbols as identifiers, which a number of languages happily
support. Using them as keywords in the language means that it has to
be not just you, but the bulk of programmers; otherwise there have to
be two ways to do everything, and everyone has to learn both of them.
(Once, say, 99% of programmers can happily type all those symbols, the
fact that 1% of programmers are using the word "lambda" will just be a
matter to be dealt with in legacy code - same as seeing "range" vs
"xrange" in Python 2 code. New code needn't concern itself with the
difference.) Unfortunately, at the moment it's more like 1% of
programmers can easily type those symbols, I would guess.

ChrisA


From steve at pearwood.info  Tue Mar 25 01:28:29 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 05:28:29 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <87bnwv2a5v.fsf@elektro.pacujo.net>
 <mailman.8446.1395661782.18130.python-list@python.org>
 <53303b8a$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmqZ1ekiBEpGDtj-P_TVJ+=0R2CMVh4GOfCvL5vci=qm2g@mail.gmail.com>
 <CALwzidk3qyeJvPZQ6CX_qmG00NNqhEwsb67WL_9eW1o9dHqdcw@mail.gmail.com>
 <mailman.8464.1395691042.18130.python-list@python.org>
Message-ID: <533113fd$0$29878$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 06:57:19 +1100, Chris Angelico wrote:

> Can you imagine a high level language without a simple notation for
> variable assignment? Certainly not.

I don't know... what a stack based or concatenative language like Forth, 
Postscript, Joy or Factor count as high-level?

I'm pretty sure Joy and Factor should. Perhaps not Forth or Postscript.

Some of these language may offer variable assignment, but using it is 
entirely optional. It's a convenience, nothing more.



-- 
Steven


From rustompmody at gmail.com  Tue Mar 25 01:28:52 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 22:28:52 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <lgr3c1$k9l$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
Message-ID: <f8fe2203-8c83-4012-81c7-3a4f30800204@googlegroups.com>

On Tuesday, March 25, 2014 10:44:42 AM UTC+5:30, Mark H. Harris wrote:
> On 3/25/14 12:08 AM, Chris Angelico wrote:

> > How quickly can you switch, type one letter (to generate one Cyrillic
> > character), and switch back?

> ... very fast.

> Is not this nicer?

>  >>> ? = pi

>  >>> sin(?/4)
> 0.7071067811865475
>  >>> cos(?/4)
> 0.7071067811865476

Looks ugly here (both Google groups and emacs)
But I think you meant small pi not capital. Redoing:

? = pi
>>> sin(?/4)
0.7071067811865475
>>> cos(?/4)
0.7071067811865476

Looks better in emacs
Input with tex mode -- 1 char to switch
slightly verbose to type -- \pi gives ? \Pi gives ?
Now to check GG...


From rosuav at gmail.com  Tue Mar 25 01:31:26 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 16:31:26 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <4576875e-29cf-42b4-ac8d-2f75fadebe20@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
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 <lgr3c1$k9l$1@speranza.aioe.org>
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Message-ID: <CAPTjJmpiokJkvsXy18jnmJFpshWtxg5E29xYZvSqmzW=PLv4Zw@mail.gmail.com>

On Tue, Mar 25, 2014 at 4:23 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> So let me talk of which input methods I use -- devanagari and tex.
> I have devanagari-itrans set up in emacs as default (other) input method
> So Ctrl-\ (ie 1? keystrokes) puts emacs into devanagari mode

Yes, but putting emacs into a different mode, typing one letter, and
putting it back into the other mode is going to be more like 5
keystrokes. And that lets you have just one other input method; if you
have more than two, the cost will be higher. So replacing "lambda"
with "?" is a minimal saving, practically zip [1] when you consider
the readability cost of having two ways of spelling the exact same
thing. For this to be useful, you'd need to be able to both read and
write much more efficiently. It has to be something where you can
quickly switch from ASCII letters and symbols to a non-ASCII lambda
and back to ASCII for the arguments and expression.

ChrisA

[1] No offense meant to the builtin function!


From harrismh777 at gmail.com  Tue Mar 25 01:34:40 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 00:34:40 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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Message-ID: <lgr4hf$mbd$1@speranza.aioe.org>

On 3/25/14 12:27 AM, Chris Angelico wrote:
>>     my pdeclib constants extension will have alternate spellings for ? and ?
>> and ? and others...
>
> That's good! (Although typing ? quicker than pi is majorly pushing it.

Well, I'll tell ya, its exactly the same--- two key-strokes, believe it 
or not.

Because the character selector is up on the gui (for me, far left) and 
the two strokes are {mouse click the ? } and {mouse click the insert}; 
rather than {p} {i} .  There is of course a brief time-lag because my 
right hand has to move the pointing device and my hand is off the 
keyboard momentarily --  that is not a problem though, on my track pad 
notebook.

marcus

PS Is it   Tuesday 04:35 pm there?  Its Tuesday way AM here; 00:35am




From harrismh777 at gmail.com  Tue Mar 25 01:36:10 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 00:36:10 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
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 <roy-66D138.23291924032014@news.panix.com>
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 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
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 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
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 <lgr3c1$k9l$1@speranza.aioe.org>
 <f8fe2203-8c83-4012-81c7-3a4f30800204@googlegroups.com>
Message-ID: <lgr4k9$mbd$2@speranza.aioe.org>

On 3/25/14 12:28 AM, Rustom Mody wrote:
> ? = pi
>>>> sin(?/4)
> 0.7071067811865475
>>>> cos(?/4)
> 0.7071067811865476
>
> Looks better in emacs
> Input with tex mode -- 1 char to switch
> slightly verbose to type -- \pi gives ? \Pi gives ?

Whoohoo... yes, way more betterer/

:)



From frank at chagford.com  Tue Mar 25 01:41:27 2014
From: frank at chagford.com (Frank Millman)
Date: Tue, 25 Mar 2014 07:41:27 +0200
Subject: Question about Source Control
References: <mailman.8190.1395061611.18130.python-list@python.org>
 <19d3ddc9-0fb9-476d-a117-e5f174eca85c@googlegroups.com>
Message-ID: <lgr4to$gl9$1@ger.gmane.org>


"Rustom Mody" <rustompmody at gmail.com> wrote in message 
news:19d3ddc9-0fb9-476d-a117-e5f174eca85c at googlegroups.com...
> On Monday, March 17, 2014 6:36:33 PM UTC+5:30, Frank Millman wrote:
>> Hi all
>
>> I know I *should* be using a Source Control Management system, but at
>> present I am not. I tried to set up Mercurial a couple of years ago, but 
>> I
>> think I set it up wrongly, as I got myself confused and found it more of 
>> a
>> hindrance than a help. Now I am ready to try again, but I want to avoid 
>> my
>> earlier mistakes.
>
>
> Seen this??
> Yeah may not apply directly to your use-case buts seems worth a read
> https://www.kernel.org/pub/software/scm/git/docs/gitworkflows.html
>
> [At command line
> $ git help -w workflows
> will give you the same
> ]

Thanks, Rustom, that was a very interesting read.

I have made a shortcut to it so that I can refer back to it as my 
understanding grows.

Frank





From rosuav at gmail.com  Tue Mar 25 01:43:40 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 16:43:40 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <533113fd$0$29878$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
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 <CALwzidk3qyeJvPZQ6CX_qmG00NNqhEwsb67WL_9eW1o9dHqdcw@mail.gmail.com>
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Message-ID: <CAPTjJmoU8jSit_v2VG6GnCEhFT18k5xpQp+Zozebz2Hcx_3RyA@mail.gmail.com>

On Tue, Mar 25, 2014 at 4:28 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Tue, 25 Mar 2014 06:57:19 +1100, Chris Angelico wrote:
>
>> Can you imagine a high level language without a simple notation for
>> variable assignment? Certainly not.
>
> I don't know... what a stack based or concatenative language like Forth,
> Postscript, Joy or Factor count as high-level?
>
> I'm pretty sure Joy and Factor should. Perhaps not Forth or Postscript.
>
> Some of these language may offer variable assignment, but using it is
> entirely optional. It's a convenience, nothing more.

Ah, sorry. I meant in languages that do have a concept of variable
assignment. Yes, some don't have it at all, so of course they don't
offer any notation for it. But any reasonably modern symbolic language
is not going to have a long and wordy notation for assignment, because
assignment is so common. It's language design Huffman coding: the
features programmers are expected to use frequently are given
convenient notations. A stack-based language will have extremely
convenient notations for "push this onto the stack", something like
"Put potatoes into the mixing bowl. Put dijon mustard into the mixing
bowl. Put lard into the mixing bowl." (okay, so Chef might not be the
best language to demonstrate this with!).

A basic iterative for loop is considered extremely common. C has a
highly compact notation that packs three parts into a simple header;
REXX has a more piece-meal approach whereby "DO I=start" can be
followed by any combination of "TO stop", "BY step", "WHILE
condition", "UNTIL condition", and "FOR count", each of which has the
same effect on its own or in combination with others. (I think WHILE
and UNTIL might be incompatible with each other, but none of the
others conflict. Having TO and FOR in the same loop header means it'll
stop when either condition is reached.) And Python doesn't have any
such construct, but *only* a 'foreach'. That's what I was talking
about; and yet it works quite nicely.

ChrisA


From rustompmody at gmail.com  Tue Mar 25 01:42:56 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 22:42:56 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <lgr4hf$mbd$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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 <lgq8th$nj4$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
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Message-ID: <2228e770-e67f-4713-b2f3-5f1e98a27e89@googlegroups.com>

On Tuesday, March 25, 2014 11:04:40 AM UTC+5:30, Mark H. Harris wrote:
> On 3/25/14 12:27 AM, Chris Angelico wrote:
> >>     my pdeclib constants extension will have alternate spellings for ? and ?
> >> and ? and others...
> > That's good! (Although typing ? quicker than pi is majorly pushing it.

> Well, I'll tell ya, its exactly the same--- two key-strokes, believe it 
> or not.

> Because the character selector is up on the gui (for me, far left) and 
> the two strokes are {mouse click the ? } and {mouse click the insert}; 
> rather than {p} {i} .  There is of course a brief time-lag because my 
> right hand has to move the pointing device and my hand is off the 
> keyboard momentarily --  that is not a problem though, on my track pad 
> notebook.

You are not counting mouse
For an emacs user
Looking at mouse counts as 3  keystrokes
Touching is more like 5-8
https://sites.google.com/site/steveyegge2/effective-emacs

vi is probably even more hardcore in that vi is more economical ergonomially





From rosuav at gmail.com  Tue Mar 25 01:48:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 16:48:43 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <lgr4hf$mbd$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
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 <lgq8th$nj4$1@speranza.aioe.org>
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Message-ID: <CAPTjJmrGx6P_FUu6LjhA7nPtBDzh28gUvJGwwdp19b9yhxCq9A@mail.gmail.com>

On Tue, Mar 25, 2014 at 4:34 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> Because the character selector is up on the gui (for me, far left) and the
> two strokes are {mouse click the ? } and {mouse click the insert}; rather
> than {p} {i} .  There is of course a brief time-lag because my right hand
> has to move the pointing device and my hand is off the keyboard momentarily
> --  that is not a problem though, on my track pad notebook.

I'd like to see millisecond timings for that; for most people, typing
is WAY quicker than seeking with the mouse, as you can type without
feedback but clicking requires that you see that the mouse is in the
right place before you hit the button. (I'm typing this, right now,
with my eyes on my MUD client on the screen 90? away  from this
computer. I'm reading the text that other people have sent to me while
writing this text. The human brain can handle that, but only so long
as I don't need my eyes to also be on the screen where I'm typing -
which means my fingers need a measure of autonomy.)

> PS Is it   Tuesday 04:35 pm there?  Its Tuesday way AM here; 00:35am

Yup. Welcome to timezones. I'm UTC +11 here, although we'll drop back
to +10 shortly as DST finishes (yay!). It's currently 0547 UTC, so
you're presumably five hours behind UTC, which would put you east
coast USA, most likely. (Especially since your mailer is putting the
dates as mm/dd/yy, which is an abomination peculiar to Americans.)

ChrisA


From steve at pearwood.info  Tue Mar 25 01:47:51 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 05:47:51 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <a434e0d3-b2e1-400d-a9a2-ac35493c2c4a@googlegroups.com>
 <mailman.8486.1395719831.18130.python-list@python.org>
Message-ID: <53311887$0$2756$c3e8da3$76491128@news.astraweb.com>

On Tue, 25 Mar 2014 14:57:02 +1100, Chris Angelico wrote:

> On Tue, Mar 25, 2014 at 2:43 PM, Rustom Mody <rustompmody at gmail.com>
> wrote:
>> What you are missing is that programmers spend 90% of their time
>> reading code
>> 10% writing code
>>
>> You may well be in the super-whiz category (not being sarcastic here)
>> All that will change is upto 70-30. (ecause you rarely make a mistake)
>> You still have to read oodles of others' code
> 
> No, I'm not missing that. But the human brain is a tokenizer, just as
> Python is. Once you know what a token means, you comprehend it as that
> token, and it takes up space in your mind as a single unit. There's not
> a lot of readability difference between a one-symbol token and a
> one-word token.

Hmmm, I don't know about that. Mathematicians are heavy users of symbols. 
Why do they write ? instead of "for all", or ? instead of "subset"?

Why do we write "40" instead of "forty"?


> Also, since the human brain works largely with words,

I think that's a fairly controversial opinion. The Chinese might have 
something to say about that.

I think that heavy use of symbols is a form of Huffman coding -- common 
things should be short, and uncommon things longer. Mathematicians tend 
to be *extremely* specialised, so they're all inventing their own Huffman 
codings, and the end result is a huge number of (often ambiguous) symbols.

Personally, I think that it would be good to start accepting, but not 
requiring, Unicode in programming languages. We can already write:

from math import pi as ?

Perhaps we should be able to write:

setA ? setB




-- 
Steven


From harrismh777 at gmail.com  Tue Mar 25 01:47:51 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 00:47:51 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
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 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
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 <lgr4hf$mbd$1@speranza.aioe.org>
 <2228e770-e67f-4713-b2f3-5f1e98a27e89@googlegroups.com>
Message-ID: <lgr5a6$nlt$1@speranza.aioe.org>

On 3/25/14 12:42 AM, Rustom Mody wrote:

> You are not counting mouse
> For an emacs user
> Looking at mouse counts as 3  keystrokes

ha!   I would not be surprised that just "thinking" about the mouse 
might be worth 3 key-strokes for an emacs user!

I use vi all the time; emacs less; depends on the project. But I cannot 
claim to be an emacs keyboard ninja (sometimes I even have to look up a 
meta sequence)  how many key-strokes is that?  never mind...

marcus




From rosuav at gmail.com  Tue Mar 25 01:54:58 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 16:54:58 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <2228e770-e67f-4713-b2f3-5f1e98a27e89@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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Message-ID: <CAPTjJmrZJMia=YhtQM+a778fnKS=meLwrqiHFq7k=9qjtPTE-Q@mail.gmail.com>

On Tue, Mar 25, 2014 at 4:42 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> You are not counting mouse
> For an emacs user
> Looking at mouse counts as 3  keystrokes
> Touching is more like 5-8
> https://sites.google.com/site/steveyegge2/effective-emacs

I think the cost of the mouse varies according to technology. I'm
currently working on two systems: my desktop (Sikorsky) with a classic
101-key keyboard (including numpad) and a mouse to the right of it,
and my laptop (Traal) with an IBM keyboard with a trackpoint (stick
mouse) in the middle of it. I can switch to Traal's mouse almost as
quickly as typing a G or H, but Sikorsky's mouse requires me to move
my entire arm across from home position to the mouse pad. (Which means
I do far FAR better playing a classic first-person shooter on Sikorsky
- I keep my left hand on WASD for movement and my right hand on the
mouse for orientation and weaponry. Much more efficient than Traal's
setup.)

But regardless of the exact cost, it's still significant. Switching to
the mouse requires (a) moving a finger or hand onto the mouse; (b)
pushing the mouse to the right position; (c) sighting the mouse cursor
on the screen; (d) adjusting the mouse position until you're where you
want to be; and finally (e) clicking, which is roughly the same cost
as one keystroke. The costs of a through d depend on environment and
circumstances (don't discount step c until you've tried this exercise
in bright sunlight), but will usually be of the order of the above 5-8
keystroke figure. You might be able to get it down to 3 keystrokes,
but not to 1.

ChrisA


From harrismh777 at gmail.com  Tue Mar 25 01:56:11 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 00:56:11 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <lgr4hf$mbd$1@speranza.aioe.org>
 <mailman.8495.1395726527.18130.python-list@python.org>
Message-ID: <lgr5pq$olp$1@speranza.aioe.org>

On 3/25/14 12:48 AM, Chris Angelico wrote:
> Yup. Welcome to timezones. I'm UTC +11 here, although we'll drop back
> to +10 shortly as DST finishes (yay!). It's currently 0547 UTC, so
> you're presumably five hours behind UTC, which would put you east
> coast USA, most likely. (Especially since your mailer is putting the
> dates as mm/dd/yy, which is an abomination peculiar to Americans.)

No, we're already DST; so we're normally UTC -6, now  UTC -5. We're CDST 
Minnesota (Southeast)

Its entirely weird working with people all over the world in seconds 
24-7 365 (we're on one tiny planet, you know?)

marcus


From harrismh777 at gmail.com  Tue Mar 25 02:01:10 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 01:01:10 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <lgr4hf$mbd$1@speranza.aioe.org>
 <mailman.8495.1395726527.18130.python-list@python.org>
Message-ID: <lgr635$p5p$1@speranza.aioe.org>

On 3/25/14 12:48 AM, Chris Angelico wrote:
> (Especially since your mailer is putting the
> dates as mm/dd/yy, which is an abomination peculiar to Americans.)

I did not know that; so is  25 Mar 2014 the preferred way?


marcus


From steve at pearwood.info  Tue Mar 25 02:04:05 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 06:04:05 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <mailman.8488.1395721200.18130.python-list@python.org>
Message-ID: <53311c54$0$2756$c3e8da3$76491128@news.astraweb.com>

On Tue, 25 Mar 2014 15:19:50 +1100, Chris Angelico wrote:

> On Tue, Mar 25, 2014 at 2:59 PM, Mark H Harris <harrismh777 at gmail.com>
> wrote:
>> I personally think the answer is extended key maps triggered by meta
>> keys shift ctrl opt alt command |  which call up full alternate
>> mappings of Greek|Latin|Math|symbols &c which can be chosen by
>> mouse|pointing device.
>>
>>
>> The mac calls these keyboard viewer, and character viewer. In that way
>> the full unicode set can be available from a standard qwerty keyboard
>> without modifying the hardware right away.
> 
> I can get up a character map on any platform fairly easily, and if not,
> I can always Google the name of the character I want and copy and paste
> from fileformat.info or some other handy site. It's not that hard. But
> if I want to say "copyright", it's still quicker for me to type nine
> letters than to hunt down U+00A9 ? to paste in somewhere. 

I hear what you are saying, but that's not *necessarily* the case. Back 
when I was a Mac user, in the 1980s and 90s, *every* application accepted 
the same keyboard shortcuts for the entire Mac character set. Nearly all 
of the chars had trivially simple mnemonics, e.g Option-p for ?. Now, I 
don't happen to remember what the mnemonic for ? (it has been 20 years 
since I was regularly using a Mac), but I remember it used to be really 
easy. Easier to type Option-whatever and get a ? than typing "copyright".

So, if applications could standardise on a single interface for at least 
the common Unicode characters [er, common for who? English speakers? 
Japanese people? Arabs? Dutch?] then things would be more like 1984 on a 
Mac...



-- 
Steven


From steve at pearwood.info  Tue Mar 25 02:07:59 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 06:07:59 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
Message-ID: <53311d3f$0$2756$c3e8da3$76491128@news.astraweb.com>

On Tue, 25 Mar 2014 00:14:42 -0500, Mark H Harris wrote:

> On 3/25/14 12:08 AM, Chris Angelico wrote:
> 
>> How quickly can you switch, type one letter (to generate one Cyrillic
>> character), and switch back?
> 
> ... very fast.
> 
> Is not this nicer?
> 
>  >>> ? = pi

That's the product operator.

py> from unicodedata import name
py> name('?')
'GREEK CAPITAL LETTER PI'

You want lower-case pi, ?.



-- 
Steven


From rosuav at gmail.com  Tue Mar 25 02:12:50 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 17:12:50 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53311887$0$2756$c3e8da3$76491128@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <a434e0d3-b2e1-400d-a9a2-ac35493c2c4a@googlegroups.com>
 <mailman.8486.1395719831.18130.python-list@python.org>
 <53311887$0$2756$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CAPTjJmqsYPxwK9BN-aBgObdDGr1pQyeHv4JoGCwKKGfWB62p=g@mail.gmail.com>

On Tue, Mar 25, 2014 at 4:47 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Tue, 25 Mar 2014 14:57:02 +1100, Chris Angelico wrote:
>> No, I'm not missing that. But the human brain is a tokenizer, just as
>> Python is. Once you know what a token means, you comprehend it as that
>> token, and it takes up space in your mind as a single unit. There's not
>> a lot of readability difference between a one-symbol token and a
>> one-word token.
>
> Hmmm, I don't know about that. Mathematicians are heavy users of symbols.
> Why do they write ? instead of "for all", or ? instead of "subset"?
>
> Why do we write "40" instead of "forty"?

Because the shorter symbols lend themselves better to the
"super-tokenization" where you don't read the individual parts but the
whole. The difference between "40" and "forty" is minimal, but the
difference between "86400" and "eighty-six thousand [and] four
hundred" is significant; the first is a single token, which you could
then instantly recognize as the number of seconds in a day (leap
seconds aside), but the second is a lengthy expression.

There's also ease of writing. On paper or blackboard, it's really easy
to write little strokes and curvy lines to mean things, and to write a
bolded letter R to mean "Real numbers". In Python, it's much easier to
use a few more ASCII letters than to write ? ?.

>> Also, since the human brain works largely with words,
>
> I think that's a fairly controversial opinion. The Chinese might have
> something to say about that.

Well, all the people I interviewed (three of them: me, myself, and I)
agree that the human brain works with words. My research is 100%
scientific, and is therefore unassailable. So there. :)

> I think that heavy use of symbols is a form of Huffman coding -- common
> things should be short, and uncommon things longer. Mathematicians tend
> to be *extremely* specialised, so they're all inventing their own Huffman
> codings, and the end result is a huge number of (often ambiguous) symbols.

Yeah. That's about the size of it. Usually, each symbol has some read
form; "? ? ?" would be read as "Naturals are a subset of Reals" (or
maybe "Naturals is a subset of Reals"?), and in program code, using
the word "subset" or "issubset" wouldn't be much worse. It would be
some worse, and the exact cost depends on how frequently your code
does subset comparisons; my view is that the worseness of words is
less than the worseness of untypable symbols. (And I'm about to be
arrested for murdering the English language.)

> Personally, I think that it would be good to start accepting, but not
> requiring, Unicode in programming languages. We can already write:
>
> from math import pi as ?
>
> Perhaps we should be able to write:
>
> setA ? setB

It would be nice, if subset testing is considered common enough to
warrant it. (I'm not sure it is, but I'm certainly not sure it isn't.)
But it violates "one obvious way". Python doesn't, as a general rule,
offer us two ways of spelling the exact same thing. So the bar for
inclusion would be quite high: it has to be so much better than the
alternative that it justifies the creation of a duplicate notation.

ChrisA


From rustompmody at gmail.com  Tue Mar 25 02:10:58 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 23:10:58 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53311887$0$2756$c3e8da3$76491128@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <a434e0d3-b2e1-400d-a9a2-ac35493c2c4a@googlegroups.com>
 <mailman.8486.1395719831.18130.python-list@python.org>
 <53311887$0$2756$c3e8da3$76491128@news.astraweb.com>
Message-ID: <8b4fd4f8-f626-4b0d-8bda-6b6813ca7403@googlegroups.com>

On Tuesday, March 25, 2014 11:17:51 AM UTC+5:30, Steven D'Aprano wrote:
> On Tue, 25 Mar 2014 14:57:02 +1100, Chris Angelico wrote:

> > wrote:
> >> What you are missing is that programmers spend 90% of their time
> >> reading code
> >> 10% writing code
> >> You may well be in the super-whiz category (not being sarcastic here)
> >> All that will change is upto 70-30. (ecause you rarely make a mistake)
> >> You still have to read oodles of others' code
> > No, I'm not missing that. But the human brain is a tokenizer, just as
> > Python is. Once you know what a token means, you comprehend it as that
> > token, and it takes up space in your mind as a single unit. There's not
> > a lot of readability difference between a one-symbol token and a
> > one-word token.

> Hmmm, I don't know about that. Mathematicians are heavy users of symbols. 
> Why do they write ? instead of "for all", or ? instead of "subset"?

> Why do we write "40" instead of "forty"?

> > Also, since the human brain works largely with words,

> I think that's a fairly controversial opinion. The Chinese might have 
> something to say about that.

> I think that heavy use of symbols is a form of Huffman coding -- common 
> things should be short, and uncommon things longer. Mathematicians tend 
> to be *extremely* specialised, so they're all inventing their own Huffman 
> codings, and the end result is a huge number of (often ambiguous) symbols.

> Personally, I think that it would be good to start accepting, but not 
> requiring, Unicode in programming languages. We can already write:

> from math import pi as ?

> Perhaps we should be able to write:

> setA ? setB

Agree with all examples -- chinese being the best!

Something that Chris may relate to:

You type a music score into lilypond
Then call lilypond to convert it into standard western staff notation

Why not put up the lilypond (ASCII) directly on the piano/organ when you play?

This is far from rhetorical... ABC,Guido,etc (not python's!) have some
claim to be *musically* (not just textually) readable and easier to
master than standard staff notation

Still for someone
- used to staff notation
- under the standard presumptions of western music:
  -- harmony
  -- spelling c# ? d?
  -- a note is a note ie C to D is as much a note as D to E

staff notation is hard to beat


From rosuav at gmail.com  Tue Mar 25 02:19:10 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 17:19:10 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <lgr635$p5p$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
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 <lgr3c1$k9l$1@speranza.aioe.org>
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 <lgr4hf$mbd$1@speranza.aioe.org>
 <mailman.8495.1395726527.18130.python-list@python.org>
 <lgr635$p5p$1@speranza.aioe.org>
Message-ID: <CAPTjJmrhPm6JX1awcTtw6q6Lf_2ZUBX6RFtYZNYJL1Hm=2St+Q@mail.gmail.com>

On Tue, Mar 25, 2014 at 4:56 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/25/14 12:48 AM, Chris Angelico wrote:
>>
>> Yup. Welcome to timezones. I'm UTC +11 here, although we'll drop back
>> to +10 shortly as DST finishes (yay!). It's currently 0547 UTC, so
>> you're presumably five hours behind UTC, which would put you east
>> coast USA, most likely. (Especially since your mailer is putting the
>> dates as mm/dd/yy, which is an abomination peculiar to Americans.)
>
>
> No, we're already DST; so we're normally UTC -6, now  UTC -5. We're CDST
> Minnesota (Southeast)
>
> Its entirely weird working with people all over the world in seconds 24-7
> 365 (we're on one tiny planet, you know?)

It is one small planet, in many ways, yes. Plus, as well as timezones,
you have different people working different schedules. Some of us are
active in the weird hours of the night, others might be posting from
work (a good bit of python-dev traffic right now involves one of Red
Hat's Python people, so it's entirely possible he's posting during
business hours his time), and others will be active here during their
evenings. Net result: The list never goes quiet!

>> (Especially since your mailer is putting the
>> dates as mm/dd/yy, which is an abomination peculiar to Americans.)
>
>
> I did not know that; so is  25 Mar 2014 the preferred way?

Putting the month in words is unambiguous (at least among users of the
Gregorian calendar or its derivatives). For numeric dates, there are
broadly three competing formats: d/m/y, m/d/y, and y/m/d. (Or using
dots or hyphens between the components, or in the case of y/m/d, no
separator at all - I'll write today's date as 20140325 in some
contexts.) Of them, y/m/d is both the clearest and the least commonly
used; with a four-digit year, there's no way it could be confused for
anything else.

ChrisA


From steve at pearwood.info  Tue Mar 25 02:16:20 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 06:16:20 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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Message-ID: <53311f33$0$2756$c3e8da3$76491128@news.astraweb.com>

On Mon, 24 Mar 2014 18:44:37 -0500, Mark H Harris wrote:

> On 3/24/14 6:01 PM, Chris Angelico wrote:
> 
>> Easy fix. Use the "explicit capture" notation:
> 
>> adders[n] = lambda a, n=n: a+n
> 
>> And there you are, out of your difficulty at once!
> 
> Yes, yes, yes,  and example:
> 
>  >>>> adders= list(range(4))
>  >>>> for n in adders:
>  >	adders[n] = lambda a, n=n: a+n
>  >
>  >
>  >>>> adders[1](3)
>  >4
>  >>>> adders[2](3)
>  >5
> 
>     But, and this is the big (WHY?) is that necessary? In other words,
> its not about experts knowing how to make this work, its about "normal"
> people not understanding in the first place why its a problem, and why
> the various solutions work to fix it; even though "we" all know that
> nothing is 'broken'.

The reason this is surprising is that people want their functions to 
magically read their mind and do what they want, even when they want it 
to do something different each time.

If you have early binding, then people who want late binding will 
complain that it does the wrong thing. If you have late binding, then 
people who want early binding will complain that it does the wrong thing. 
Even when they are the same people.


And *none of this has anything to do with lambda*. Functions created with 
def exhibit the exact same behaviour.



-- 
Steven


From steve at pearwood.info  Tue Mar 25 02:20:20 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 06:20:20 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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Message-ID: <53312023$0$2756$c3e8da3$76491128@news.astraweb.com>

On Mon, 24 Mar 2014 17:58:11 -0600, Ian Kelly wrote:

> On Mon, Mar 24, 2014 at 3:43 PM, Mark H Harris <harrismh777 at gmail.com>
> wrote:
>>    Aside from the sin of spelling out "lambda,"
>>       should be   ( \x y -> x + y ) a b )  but, neither here nor
>>       there...
> 
> Well no, it *should* be ?x y . x + y but apparently some people don't
> have that character on their keyboards, so it gets written as lambda or
> \ instead. 


Holy cow! Is that where the Haskell syntax comes from?

I never would have guessed in a million years that backslash \ was meant 
to be an ASCII-ified version of lambda. What a stupid idea that is. 
Writing "lambda" out in full is much more sensible.

> Personally I dislike the \ style; it doesn't really resemble
> a ? that closely, and to me the backslash denotes escape sequences and
> set differences.  Nor is Python alone in spelling out lambda: Scheme and
> Common Lisp spell it the same way. As far as I know the \ for ? is
> unique to Haskell.

At least they don't spell it "fun". 



-- 
Steven


From rosuav at gmail.com  Tue Mar 25 02:26:48 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 17:26:48 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53311c54$0$2756$c3e8da3$76491128@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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Message-ID: <CAPTjJmokYJsv8Lwp=iLDzZf-G_gwY01gFpp-DtWgofZ-F==4ZQ@mail.gmail.com>

On Tue, Mar 25, 2014 at 5:04 PM, Steven D'Aprano <steve at pearwood.info> wrote:
>> I can get up a character map on any platform fairly easily, and if not,
>> I can always Google the name of the character I want and copy and paste
>> from fileformat.info or some other handy site. It's not that hard. But
>> if I want to say "copyright", it's still quicker for me to type nine
>> letters than to hunt down U+00A9 ? to paste in somewhere.
>
> I hear what you are saying, but that's not *necessarily* the case. Back
> when I was a Mac user, in the 1980s and 90s, *every* application accepted
> the same keyboard shortcuts for the entire Mac character set. Nearly all
> of the chars had trivially simple mnemonics, e.g Option-p for ?. Now, I
> don't happen to remember what the mnemonic for ? (it has been 20 years
> since I was regularly using a Mac), but I remember it used to be really
> easy. Easier to type Option-whatever and get a ? than typing "copyright".

Easy enough with a restricted character set. When you're working with,
say, 128 common characters and another 128 less common, it's not too
hard to organize keystrokes for them all.

> So, if applications could standardise on a single interface for at least
> the common Unicode characters [er, common for who? English speakers?
> Japanese people? Arabs? Dutch?] then things would be more like 1984 on a
> Mac...

And that's the problem. So what we'll have is a programming interface
that makes it easy to type a bunch of symbols used in code, and it'll
differ from pretty much everything else, and if you want to type
lambda into an email you have to jump over to your code window, key it
in, and then copy/paste... it wouldn't work without it being pretty
much universal.

ChrisA


From steve at pearwood.info  Tue Mar 25 02:28:04 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 06:28:04 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
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 <lgqhsf$ehi$1@speranza.aioe.org>
Message-ID: <533121f4$0$2756$c3e8da3$76491128@news.astraweb.com>

On Mon, 24 Mar 2014 19:16:15 -0500, Mark H Harris wrote:

> On 3/24/14 7:11 PM, Chris Angelico wrote:
>> On Tue, Mar 25, 2014 at 10:56 AM, Mark H Harris<harrismh777 at gmail.com> 
>> wrote:
>>> What is needed is the explicit closure "grab" recommended by ChrisA.
>>
>> Which does work. You do know why, right?
> 
> Sure.  ... but again, that's not the point. The point is NOT can you
> explain why it works, the point is that as a lambda construct it is NOT
> clear why it works, and because the construct does not match what lambda
> users might expect (naturally) there are *constant* questions about it.
> 
> So, again, I'll restate that the community might consider (over time)
> whether the confusion created by lambda in python


Functions created with def work exactly the same way. If you are 
surprised by lambda's binding behaviour, and you replace the lambda with 
def, you will still be confused. You'll have gone from a nice, concise 
expression to a bulky statement, and be no better off. You'll be worse 
off.


-- 
Steven


From rosuav at gmail.com  Tue Mar 25 02:33:24 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 17:33:24 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <8b4fd4f8-f626-4b0d-8bda-6b6813ca7403@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
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 <mailman.8440.1395651801.18130.python-list@python.org>
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Message-ID: <CAPTjJmrnkpzSakZ8np+mbVG+JK9geTwaY=O5DjO4jDw0=iQpRQ@mail.gmail.com>

On Tue, Mar 25, 2014 at 5:10 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> Something that Chris may relate to:
>
> You type a music score into lilypond
> Then call lilypond to convert it into standard western staff notation
>
> Why not put up the lilypond (ASCII) directly on the piano/organ when you play?
>
> This is far from rhetorical... ABC,Guido,etc (not python's!) have some
> claim to be *musically* (not just textually) readable and easier to
> master than standard staff notation
>
> Still for someone
> - used to staff notation
> - under the standard presumptions of western music:
>   -- harmony
>   -- spelling c# ? d?
>   -- a note is a note ie C to D is as much a note as D to E
>
> staff notation is hard to beat

I wouldn't say it's hard to beat... I happily beat time while looking
at staff notation!

(Of course, I shouldn't beat time. He doesn't like that.)

Staff notation isn't perfect by any means (and there've been various
projects to improve on it), but it's a lot better than the "source
code" form in Lilypond. This is partly because my source code tends to
look at multiple (often four) separate lines of harmony, often plus a
separate line of chords, but when I'm playing, I want to be able to
eyeball all of it at once.

But I've used WYSIWYG notation editors plenty, and *for note entry*
they offer me nothing above Lilypond's notation. I don't yearn to be
able to scribble notes on a paper staff, scan it in, and have that
functional. I don't look back with longing at NoteWorthy Composer (for
which I do own a license, and could probably hunt down the install CD
if I tried). There's a huge difference between the two.

ChrisA


From rustompmody at gmail.com  Tue Mar 25 02:35:50 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 23:35:50 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8497.1395727978.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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 <mailman.8497.1395727978.18130.python-list@python.org>
Message-ID: <fbc48b99-2d54-4484-8d3b-865b103203f5@googlegroups.com>

On Tuesday, March 25, 2014 11:42:50 AM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 4:47 PM, Steven D'Aprano wrote:
> > On Tue, 25 Mar 2014 14:57:02 +1100, Chris Angelico wrote:
> >> No, I'm not missing that. But the human brain is a tokenizer, just as
> >> Python is. Once you know what a token means, you comprehend it as that
> >> token, and it takes up space in your mind as a single unit. There's not
> >> a lot of readability difference between a one-symbol token and a
> >> one-word token.
> > Hmmm, I don't know about that. Mathematicians are heavy users of symbols.
> > Why do they write ? instead of "for all", or ? instead of "subset"?
> > Why do we write "40" instead of "forty"?

> Because the shorter symbols lend themselves better to the
> "super-tokenization" where you don't read the individual parts but the
> whole. The difference between "40" and "forty" is minimal, but the
> difference between "86400" and "eighty-six thousand [and] four
> hundred" is significant; the first is a single token, which you could
> then instantly recognize as the number of seconds in a day (leap
> seconds aside), but the second is a lengthy expression.

> There's also ease of writing. On paper or blackboard, it's really easy
> to write little strokes and curvy lines to mean things, and to write a
> bolded letter R to mean "Real numbers". In Python, it's much easier to
> use a few more ASCII letters than to write ? ?.

> >> Also, since the human brain works largely with words,
> > I think that's a fairly controversial opinion. The Chinese might have
> > something to say about that.

> Well, all the people I interviewed (three of them: me, myself, and I)
> agree that the human brain works with words. My research is 100%
> scientific, and is therefore unassailable. So there. :)

> > I think that heavy use of symbols is a form of Huffman coding -- common
> > things should be short, and uncommon things longer. Mathematicians tend
> > to be *extremely* specialised, so they're all inventing their own Huffman
> > codings, and the end result is a huge number of (often ambiguous) symbols.

> Yeah. That's about the size of it. Usually, each symbol has some read
> form; "? ? ?" would be read as "Naturals are a subset of Reals" (or
> maybe "Naturals is a subset of Reals"?), and in program code, using
> the word "subset" or "issubset" wouldn't be much worse. It would be
> some worse, and the exact cost depends on how frequently your code
> does subset comparisons; my view is that the worseness of words is
> less than the worseness of untypable symbols. (And I'm about to be
> arrested for murdering the English language.)

> > Personally, I think that it would be good to start accepting, but not
> > requiring, Unicode in programming languages. We can already write:
> > from math import pi as ?
> > Perhaps we should be able to write:
> > setA ? setB

> It would be nice, if subset testing is considered common enough to
> warrant it. (I'm not sure it is, but I'm certainly not sure it isn't.)
> But it violates "one obvious way". Python doesn't, as a general rule,
> offer us two ways of spelling the exact same thing. So the bar for
> inclusion would be quite high: it has to be so much better than the
> alternative that it justifies the creation of a duplicate notation.

I dont think we are anywhere near making real suggestions for real changes
which would need to talk of compatibility, portability, editor support
and all such other good stuff.

Just a bit of brainstorming to see how an alternative python would look like:

Heres a quickly made list of symbols that may be nice to have support for

?
?
?
?
?
?
?
?
? 
?
?
? 
?
?
?
?
?
?
?
? (ellipsis instead of range)



From rustompmody at gmail.com  Tue Mar 25 02:41:57 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 23:41:57 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8500.1395729208.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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Message-ID: <592062d8-37a1-4f80-a9db-b3b17a6215b9@googlegroups.com>

On Tuesday, March 25, 2014 12:03:24 PM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 5:10 PM, Rustom Mody wrote:
> > Something that Chris may relate to:
> > You type a music score into lilypond
> > Then call lilypond to convert it into standard western staff notation
> > Why not put up the lilypond (ASCII) directly on the piano/organ when you play?
> > This is far from rhetorical... ABC,Guido,etc (not python's!) have some
> > claim to be *musically* (not just textually) readable and easier to
> > master than standard staff notation
> > Still for someone
> > - used to staff notation
> > - under the standard presumptions of western music:
> >   -- harmony
> >   -- spelling c# ? d?
> >   -- a note is a note ie C to D is as much a note as D to E
> > staff notation is hard to beat

> I wouldn't say it's hard to beat... I happily beat time while looking
> at staff notation!

> (Of course, I shouldn't beat time. He doesn't like that.)

> Staff notation isn't perfect by any means (and there've been various
> projects to improve on it), but it's a lot better than the "source
> code" form in Lilypond. This is partly because my source code tends to
> look at multiple (often four) separate lines of harmony, often plus a
> separate line of chords, but when I'm playing, I want to be able to
> eyeball all of it at once.

ALl of which is isomorphic to Steven's point that forty is less
eyeballable than 40

And mine that ? is more eyeballable than set([])


From rosuav at gmail.com  Tue Mar 25 02:45:11 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 17:45:11 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <fbc48b99-2d54-4484-8d3b-865b103203f5@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <a434e0d3-b2e1-400d-a9a2-ac35493c2c4a@googlegroups.com>
 <mailman.8486.1395719831.18130.python-list@python.org>
 <53311887$0$2756$c3e8da3$76491128@news.astraweb.com>
 <mailman.8497.1395727978.18130.python-list@python.org>
 <fbc48b99-2d54-4484-8d3b-865b103203f5@googlegroups.com>
Message-ID: <CAPTjJmrH-npziMT9t=SP0oj4_g_NWvmkTs8Ss1CrELUURMYkyw@mail.gmail.com>

On Tue, Mar 25, 2014 at 5:35 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> I dont think we are anywhere near making real suggestions for real changes
> which would need to talk of compatibility, portability, editor support
> and all such other good stuff.
>
> Just a bit of brainstorming to see how an alternative python would look like:
>
> Heres a quickly made list of symbols that may be nice to have support for
>
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ?
> ? (ellipsis instead of range)

Most of those look fine, but that's a fair bunch of characters you'd
need to type. And will you stop there? Would other symbols want to be
typable too? And if you have ellipsis (the character) would you also
support three consecutive U+002E to mean the same thing? (People
*will* type it that way, and would be extremely annoyed if it didn't
work.)

And will you turn Python into APL?

ChrisA


From harrismh777 at gmail.com  Tue Mar 25 02:48:00 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 01:48:00 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
Message-ID: <lgr8qv$ie$1@speranza.aioe.org>

On 3/25/14 12:08 AM, Chris Angelico wrote:
> How quickly can you switch, type one letter (to generate one Cyrillic
> character), and switch back?

Ok.. after installing Ukelete from Summer Institute of Linguistics SIL I 
can now edit the installed keymaps and select them from input sources at 
the top of the menu bar.

So, I mapped the alt-l key to ? and whalla, lambda in zero time; 
whoohoo.  Same for ?,  just alt-p. Control has an entire blank page for 
key mappings so the sky is the limit.

very fast, no mouse


marcus  ? ?




From rosuav at gmail.com  Tue Mar 25 02:50:53 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 17:50:53 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <592062d8-37a1-4f80-a9db-b3b17a6215b9@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org>
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 <a434e0d3-b2e1-400d-a9a2-ac35493c2c4a@googlegroups.com>
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 <53311887$0$2756$c3e8da3$76491128@news.astraweb.com>
 <8b4fd4f8-f626-4b0d-8bda-6b6813ca7403@googlegroups.com>
 <mailman.8500.1395729208.18130.python-list@python.org>
 <592062d8-37a1-4f80-a9db-b3b17a6215b9@googlegroups.com>
Message-ID: <CAPTjJmpYxoSgt78y0BzYK6kgEwcw4xSXbYhN1YfrNLVkvfoMCw@mail.gmail.com>

On Tue, Mar 25, 2014 at 5:41 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> ALl of which is isomorphic to Steven's point that forty is less
> eyeballable than 40
>
> And mine that ? is more eyeballable than set([])

I don't disagree that it is; the short tokens are easier to read in
quantity. I just don't think that it's sufficient to justify piles of
new and hard-to-look-up operators and things. (And a literal notation
for an empty set would be a good thing. If I were designing a
Python-like language from scratch now, I'd probably differentiate sets
and dictionaries better, which would allow each one to have its own
empty literal.)

ChrisA


From rustompmody at gmail.com  Tue Mar 25 02:52:11 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 24 Mar 2014 23:52:11 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8501.1395729915.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <a434e0d3-b2e1-400d-a9a2-ac35493c2c4a@googlegroups.com>
 <mailman.8486.1395719831.18130.python-list@python.org>
 <53311887$0$2756$c3e8da3$76491128@news.astraweb.com>
 <mailman.8497.1395727978.18130.python-list@python.org>
 <fbc48b99-2d54-4484-8d3b-865b103203f5@googlegroups.com>
 <mailman.8501.1395729915.18130.python-list@python.org>
Message-ID: <8428b099-9130-4a37-8f67-eeeb61a416a8@googlegroups.com>

On Tuesday, March 25, 2014 12:15:11 PM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 5:35 PM, Rustom Mody wrote:
> > I dont think we are anywhere near making real suggestions for real changes
> > which would need to talk of compatibility, portability, editor support
> > and all such other good stuff.
> > Just a bit of brainstorming to see how an alternative python would look like:
> > Heres a quickly made list of symbols that may be nice to have support for
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ?
> > ? (ellipsis instead of range)

> Most of those look fine, but that's a fair bunch of characters you'd
> need to type. And will you stop there? Would other symbols want to be
> typable too? And if you have ellipsis (the character) would you also
> support three consecutive U+002E to mean the same thing? (People
> *will* type it that way, and would be extremely annoyed if it didn't
> work.)

> And will you turn Python into APL?

Yes APL is a good example to learn mistakes from
- being before its time/technology
- taking a good idea too far
- assuming that I understand clearly implies so do others
- maybe some others

As for ellipsis I guess its misguided
[Was actually looking for 'center-ellipsis' which would not be so ambiguous]


From steve at pearwood.info  Tue Mar 25 02:52:13 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 06:52:13 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org>
Message-ID: <5331279c$0$2756$c3e8da3$76491128@news.astraweb.com>

On Mon, 24 Mar 2014 21:39:33 -0500, Mark H Harris wrote:

> On 3/24/14 8:20 PM, Terry Reedy wrote:
>> On 3/24/2014 7:56 PM, Mark H Harris wrote:
> 
>>> the list which is used for each of the adder[] functions created.
>>
>> Wrong. Functions look up global and nonlocal names, such as n, when the
>> function is called.
>>
>>
> hi Terry, yeah, I know; this is what's *wrong* all at once.
> 
> Functions "look up global and nonlocal names" such as n, is semantics
> for "each created function 'grabs' the last number (n) in the list",
> well, because that (n) is bound at call-time to (3).
> 
> Your version semantically is detailed and correct; my version
> semantically is "how it is perceived" by the user, which is also
> correct.

No it isn't. You can demonstrate that some mental models are closer to 
the actual behaviour of the interpreter, while other models are 
incorrect, by writing just a little more complex code. 


py> def test(arg):
...     results = []
...     for n in [1, 2, 3, 4]:
...         results.append(lambda: n)
...     n = arg
...     return results
... 
py> for func in test(1000):
...     print(func())
... 
1000
1000
1000
1000


The functions don't grab the last value from the list. They see whatever 
value the variable n has at the time the function is called.

Are you surprised by this? If you are, it is because you haven't thought 
it through in any detail. Let me show you something superficially 
different:


py> funcs = []
py> for n in [1, 2, 3, 4]:
...     def f():
...             return n
...     funcs.append(f)
... 
py> n = 1000
py> for f in funcs:
...     print(f())
... 
1000
1000
1000
1000


Are you still surprised? I bet you aren't. How else would you expect a 
variable to work?


Early binding may be *useful* sometimes, but it would be terribly 
surprising if it were the default:

my_name = "Fred"
def greet():
    print("Hello", my_name)

my_name = "Barney"
greet()

Would you expect to see "Hello Fred"?

The problem here is that Python is consistent, but people *want* it to be 
inconsistent. When it doesn't magically read their mind, they get 
"confused" that it isn't working the way they "expected".




-- 
Steven


From steve at pearwood.info  Tue Mar 25 03:03:30 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 07:03:30 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <lgr4hf$mbd$1@speranza.aioe.org>
 <mailman.8495.1395726527.18130.python-list@python.org>
 <lgr635$p5p$1@speranza.aioe.org>
 <mailman.8498.1395728360.18130.python-list@python.org>
Message-ID: <53312a42$0$2756$c3e8da3$76491128@news.astraweb.com>

On Tue, 25 Mar 2014 17:19:10 +1100, Chris Angelico wrote:

> I'll write today's date as 20140325 in some contexts.) Of them,
> y/m/d is both the clearest and the least commonly used; with a
> four-digit year, there's no way it could be confused for anything else.

Shame on you Chris! Don't you know the One True Way to write unambiguous 
dates is the ISO data format? 

2014-03-25


-- 
Steven


From steve at pearwood.info  Tue Mar 25 03:03:49 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 07:03:49 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
Message-ID: <53312a54$0$2756$c3e8da3$76491128@news.astraweb.com>

On Mon, 24 Mar 2014 20:56:19 -0700, Rustom Mody wrote:

> Paren vs tuples: why do we need to write (x,) not (x)


You don't. You can write x, without the brackets:

py> t = 23,
py> type(t)
<class 'tuple'>


It's the comma that makes tuples, not the brackets.


-- 
Steven


From rosuav at gmail.com  Tue Mar 25 03:12:06 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 18:12:06 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53312a42$0$2756$c3e8da3$76491128@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
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 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <lgr4hf$mbd$1@speranza.aioe.org>
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 <lgr635$p5p$1@speranza.aioe.org>
 <mailman.8498.1395728360.18130.python-list@python.org>
 <53312a42$0$2756$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CAPTjJmq0R295yEQtWVPy6iq6n23DpmjWEu0fHFdfD7NyUdjQqA@mail.gmail.com>

On Tue, Mar 25, 2014 at 6:03 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Tue, 25 Mar 2014 17:19:10 +1100, Chris Angelico wrote:
>
>> I'll write today's date as 20140325 in some contexts.) Of them,
>> y/m/d is both the clearest and the least commonly used; with a
>> four-digit year, there's no way it could be confused for anything else.
>
> Shame on you Chris! Don't you know the One True Way to write unambiguous
> dates is the ISO data format?
>
> 2014-03-25

Bah, BIND won't let me use ISO format!

rosuav at sikorsky:~$ dig kepl.com.au soa +short
gideon.rosuav.com. domainmaster.kepl.com.au. 2014030601 7200 3600 2419200 604800

Looks like I last edited that on the 6th inst.

But yes, hyphens are more common than slashes for delimited ymd dates.

ChrisA


From rustompmody at gmail.com  Tue Mar 25 03:22:27 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 25 Mar 2014 00:22:27 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53312a54$0$2756$c3e8da3$76491128@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
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 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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 <53312a54$0$2756$c3e8da3$76491128@news.astraweb.com>
Message-ID: <256f713b-c8b9-4cf3-a403-6865288fbef6@googlegroups.com>

On Tuesday, March 25, 2014 12:33:49 PM UTC+5:30, Steven D'Aprano wrote:
> On Mon, 24 Mar 2014 20:56:19 -0700, Rustom Mody wrote:

> > Paren vs tuples: why do we need to write (x,) not (x)

> You don't. You can write x, without the brackets:

> py> t = 23,
> py> type(t)

> It's the comma that makes tuples, not the brackets.

Yeah Chris already corrected that misconception of mine
Doesn't chage my point much though -- () overloaded to ',' overloaded



From dieter at handshake.de  Tue Mar 25 03:27:04 2014
From: dieter at handshake.de (dieter)
Date: Tue, 25 Mar 2014 08:27:04 +0100
Subject: Asyncio (or something better) for control of a vacuum
 system/components.
References: <CAB4DN0U=4VBTow9cXgdotqfnrkvcx=Hr2UprM=Hup1W+JzibPQ@mail.gmail.com>
Message-ID: <87y4zy3fhz.fsf@handshake.de>

Shishir <shishirk at gmail.com> writes:
> ...
> I am writing a software to control and monitor a vacuum
> furnace+attachments. It has a few mass flow controllers, a butterfly valve,
> a labjack unit for analog/digital outputs etc. They use RS485, RS232 and
> USB to communicate with the computer and follow special protocols for
> commands and response. The response time to execute commands can be from 5
> ms to 1 s.
>
> To achieve this, I thought of a server which reads commands on a network
> connections, parses the command and calls methods of appropriate device
> classes, which then use the corresponding channel protocol to execute the
> command. The response provided by the devices (flow controllers, valve) is
> sent back on the network connection.
>
> As there can be multiple clients (e.g. for monitoring from several
> computers), and some commands can take long, the server should not block
> when getting a command executed.

"Asyncio" is targeted at asynchronous (i.e. non-blocking) input/output.

To ensure that the server remains responsive during command execution,
you will need something in addition - e.g. threads or subprocesses.
This way, the commands can be executed (by a separate thread/subprocess)
while the server is still listening to communication.

I know of one framework which supports this kind of interaction:
"medusa/ZServer". However, it is targeted mainly towards standard
internet communication protocols ("HTTP", "FTP", ...).


>From your message, I have gained the impression that you want to support
multiple (concurrent) requests on the same communication channel.
This significantly complicates the task as the responses to those
requests may arrive out of order and may even mix with one another
(on the channel), unless you avoid this carefully.

The "medusa/ZServer" framework (mentioned above) supports HTTP pipelining (i.e.
the client can issue multiple requests without waiting for a response).
However, it starts processing of a request only when all previous
requests from the same (communication) channel have been completed.
This way, it ensures that all responses are delivered in the
same order as the requests (as required by HTTP pipelining).

If out of order responses must be supported, then "medusa/ZServer"
is not an appropriate approach. Special logic is then necessary on
both server and client to associate the responses to the proper
requests.




From dieter at handshake.de  Tue Mar 25 03:49:09 2014
From: dieter at handshake.de (dieter)
Date: Tue, 25 Mar 2014 08:49:09 +0100
Subject: gdb python how to output integer for examine memory
References: <e1e8c3a2-5d8d-4aae-9a5d-82af79be8c4c@googlegroups.com>
Message-ID: <87txam3eh6.fsf@handshake.de>

Wesley <nispray at gmail.com> writes:

>   I am trying to use gdb debug python script.
> I am using gdb7.7 and python2.7.6, here is my simple test script: 
> import time
>
> def next(i):
>     time.sleep(10)
>     i = 1 - i
>
> i = 1
> while True:
>     next(i)
> When this script running, gdb attach to it, and here is snippet:
>
> ...
> (gdb) frame 5
> #5  0x00000000004d01a7 in PyEval_EvalFrameEx (f=Frame 0x201e130, for file test.py, line 6, in next (i=1), throwflag=0) at Python/ceval.c:2666
> 2666                x = call_function(&sp, oparg);
> (gdb) py-locals
> i = 1
> (gdb) pyo i
> No symbol "i" in current context.

Quite a lot of time has passed since I last had to debug Python
processes at C level -- thus, my memory may be unreliable.

When I remember right, then "pyo" is used to interprete
a C level variable as a Python object (and print it) -- not
a Python level variable. In your case, "i" is a Python level variable.

You must carefully distinguish between the C level and the Python level.
Some commands expect C level names/objects;
others may expect Python level names/objects.

To learn how you can obtain the value of a Python variable,
I see two approaches: look through the list of provided commands
(and their documentation) and try to figure out which might be applicable
and then may some tests; or look at the implementation of "py-locals"
and use this knowledge to define you own command (for this,
you will also need to understand the gdb language to define commands).



From dieter at handshake.de  Tue Mar 25 03:53:12 2014
From: dieter at handshake.de (dieter)
Date: Tue, 25 Mar 2014 08:53:12 +0100
Subject: Memory error
References: <d4489c2b-6650-45b6-bcb0-7a1b648192d2@googlegroups.com>
Message-ID: <87ppla3eaf.fsf@handshake.de>

Jamie Mitchell <jamiemitchell1604 at gmail.com> writes:
> ...
> I then get a memory error:
>
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "/usr/local/sci/lib/python2.7/site-packages/scipy/stats/stats.py", line 2409, in pearsonr
>     x = np.asarray(x)
>   File "/usr/local/sci/lib/python2.7/site-packages/numpy/core/numeric.py", line 321, in asarray
>     return array(a, dtype, copy=False, order=order)
> MemoryError

"MemoryError" means that Python cannot get sufficent memory
from the operating system.


You have already found out one mistake. Should you continue to
get "MemoryError" after this is fixed, then your system does not
provide enough resources (memory) to solve the problem at hand.
You would need to find a way to provide more resources.



From marko at pacujo.net  Tue Mar 25 04:05:04 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 25 Mar 2014 10:05:04 +0200
Subject: Time we switched to unicode?
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
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 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
Message-ID: <87ior2zosv.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Tue, Mar 25, 2014 at 4:14 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
>>>>> ? = pi
>
> That's good! (Although typing ? quicker than pi is majorly pushing it.

It don't think that's good. The lower-case letter ? should be used. The
upper-case letter is used for a product, although unicode dedicates a
separate character for the purpose: ?.

I often see Americans, especially, confuse upper and lower-case letters
in symbols ("KM" for "km", "L" for "l" etc). However, we are dealing
with case-sensitive programming languages, so our eyes should have been
trained to address meaning to upper and lower case.


Marko


From nispray at gmail.com  Tue Mar 25 04:07:13 2014
From: nispray at gmail.com (Wesley)
Date: Tue, 25 Mar 2014 01:07:13 -0700 (PDT)
Subject: gdb python how to output integer for examine memory
In-Reply-To: <mailman.8505.1395733762.18130.python-list@python.org>
References: <e1e8c3a2-5d8d-4aae-9a5d-82af79be8c4c@googlegroups.com>
 <mailman.8505.1395733762.18130.python-list@python.org>
Message-ID: <2aa794ce-7cc1-4d24-a30b-3fb17b89e33f@googlegroups.com>

? 2014?3?25????UTC+8??3?49?09??dieter???
> Wesley <nispray at gmail.com> writes:
> 
> 
> 
> >   I am trying to use gdb debug python script.
> 
> > I am using gdb7.7 and python2.7.6, here is my simple test script: 
> 
> > import time
> 
> >
> 
> > def next(i):
> 
> >     time.sleep(10)
> 
> >     i = 1 - i
> 
> >
> 
> > i = 1
> 
> > while True:
> 
> >     next(i)
> 
> > When this script running, gdb attach to it, and here is snippet:
> 
> >
> 
> > ...
> 
> > (gdb) frame 5
> 
> > #5  0x00000000004d01a7 in PyEval_EvalFrameEx (f=Frame 0x201e130, for file test.py, line 6, in next (i=1), throwflag=0) at Python/ceval.c:2666
> 
> > 2666                x = call_function(&sp, oparg);
> 
> > (gdb) py-locals
> 
> > i = 1
> 
> > (gdb) pyo i
> 
> > No symbol "i" in current context.
> 
> 
> 
> Quite a lot of time has passed since I last had to debug Python
> 
> processes at C level -- thus, my memory may be unreliable.
> 
> 
> 
> When I remember right, then "pyo" is used to interprete
> 
> a C level variable as a Python object (and print it) -- not
> 
> a Python level variable. In your case, "i" is a Python level variable.
> 
> 
> 
> You must carefully distinguish between the C level and the Python level.
> 
> Some commands expect C level names/objects;
> 
> others may expect Python level names/objects.
> 
> 
> 
> To learn how you can obtain the value of a Python variable,
> 
> I see two approaches: look through the list of provided commands
> 
> (and their documentation) and try to figure out which might be applicable
> 
> and then may some tests; or look at the implementation of "py-locals"
> 
> and use this knowledge to define you own command (for this,
> 
> you will also need to understand the gdb language to define commands).

Hi Dieter,
  Thanks.
Actually, I can now see the varialbe names at Python level and C level.
I just want to verify x command to monitor the memory content.
So, in my origin post, I can get variable i's address, and see the value is 1,
then, I wanna have a try x command, the issue is, when use x/format i's address, the output is not 1, but other things:-(


From rosuav at gmail.com  Tue Mar 25 04:23:45 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 19:23:45 +1100
Subject: Time we switched to unicode?
In-Reply-To: <87ior2zosv.fsf@elektro.pacujo.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
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 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <87ior2zosv.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmrszmaFOUL0NA2_dun95FTtTT7yrrTstoXztTxESLa2HQ@mail.gmail.com>

On Tue, Mar 25, 2014 at 7:05 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> On Tue, Mar 25, 2014 at 4:14 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
>>>>>> ? = pi
>>
>> That's good! (Although typing ? quicker than pi is majorly pushing it.
>
> It don't think that's good. The lower-case letter ? should be used. The
> upper-case letter is used for a product, although unicode dedicates a
> separate character for the purpose: ?.
>
> I often see Americans, especially, confuse upper and lower-case letters
> in symbols ("KM" for "km", "L" for "l" etc). However, we are dealing
> with case-sensitive programming languages, so our eyes should have been
> trained to address meaning to upper and lower case.

This has been pointed out multiple times, and I did notice it myself.
But it's not significant, and I was trying to avoid nit-picking. If
you can type a capital ?, you can type a lower-case ?, unless there's
something very weird going on. So it still makes his point.

ChrisA


From steve at pearwood.info  Tue Mar 25 04:59:14 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 08:59:14 GMT
Subject: Time we switched to unicode?
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
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 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
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 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
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 <lgr3c1$k9l$1@speranza.aioe.org>
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 <87ior2zosv.fsf@elektro.pacujo.net>
 <mailman.8507.1395735829.18130.python-list@python.org>
Message-ID: <53314562$0$2756$c3e8da3$76491128@news.astraweb.com>

On Tue, 25 Mar 2014 19:23:45 +1100, Chris Angelico wrote:

> I was trying to avoid nit-picking

What, on comp.lang.python? What's wrong with you?


:-)


-- 
Steven


From rosuav at gmail.com  Tue Mar 25 05:03:05 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 20:03:05 +1100
Subject: Time we switched to unicode?
In-Reply-To: <53314562$0$2756$c3e8da3$76491128@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
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 <lgr3c1$k9l$1@speranza.aioe.org>
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 <87ior2zosv.fsf@elektro.pacujo.net>
 <mailman.8507.1395735829.18130.python-list@python.org>
 <53314562$0$2756$c3e8da3$76491128@news.astraweb.com>
Message-ID: <CAPTjJmrhY3M=2xX7kcDRGhNiZGaGVV7TPOh3LUJF6t3T-zFJkw@mail.gmail.com>

On Tue, Mar 25, 2014 at 7:59 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Tue, 25 Mar 2014 19:23:45 +1100, Chris Angelico wrote:
>
>> I was trying to avoid nit-picking
>
> What, on comp.lang.python? What's wrong with you?
>
>
> :-)

I know, it's like refraining from bike-shedding on python-ideas or not
reading the Bible in a Presbyterian church service. But occasionally I
do try to be polite, or to make a point without worrying about the
detlais... :)

ChrisA


From antoon.pardon at rece.vub.ac.be  Tue Mar 25 05:43:29 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 25 Mar 2014 10:43:29 +0100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
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Message-ID: <53314FC1.2010603@rece.vub.ac.be>

On 25-03-14 06:08, Chris Angelico wrote:

> On Tue, Mar 25, 2014 at 4:00 PM, Rustom Mody <rustompmody at gmail.com> wrote:
>> Its already there -- and even easier
>> Switch to cyrillic-jis-russian (whatever that is!)
>> and I get ? from k ? from K
> How quickly can you switch, type one letter (to generate one Cyrillic
> character), and switch back? If you can do that more quickly than
> typing a word, then (for you!) it might be worth using those letters
> as symbols.
>
> ChrisA
>
I thought programs were read more than written. So if writing is made
a bit more problematic but the result is more readable because we are
able to use symbols that are already familiar from other contexts, I
would say it is worth it.

-- 
Antoon Pardon



From rosuav at gmail.com  Tue Mar 25 05:54:51 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 20:54:51 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53314FC1.2010603@rece.vub.ac.be>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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 <lgq8th$nj4$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
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 <53314FC1.2010603@rece.vub.ac.be>
Message-ID: <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>

On Tue, Mar 25, 2014 at 8:43 PM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> I thought programs were read more than written. So if writing is made
> a bit more problematic but the result is more readable because we are
> able to use symbols that are already familiar from other contexts, I
> would say it is worth it.

It's a matter of extents. If code is read ten times for every time
it's written, making it twenty times harder to write and a little bit
easier to read is still a bad tradeoff.

Also: To what extent IS that symbol familiar from some other context?
Are you using Python as a programming language, or should you perhaps
be using a mathematical front-end? Not everything needs to perfectly
match what anyone from any other context will expect. This is, first
and foremost, a *programming* language.

ChrisA


From dihedral88888 at gmail.com  Tue Mar 25 06:17:11 2014
From: dihedral88888 at gmail.com (88888 Dihedral)
Date: Tue, 25 Mar 2014 03:17:11 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8369.1395437459.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
Message-ID: <7dd79fea-37c9-4c61-bcb7-22bb5b58b67b@googlegroups.com>


> >>> x = [[1, 2], [3, 4]]
> 
> >>> for x in x:
> 
> ...     for x in x:
> 
> ...         print(x)
> 
This is valid in the syntax level 
in python. But it is only good
for those  writing obscure programs in 
my opinions at most team works. 


From antoon.pardon at rece.vub.ac.be  Tue Mar 25 06:24:29 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 25 Mar 2014 11:24:29 +0100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
Message-ID: <5331595D.5020008@rece.vub.ac.be>

On 25-03-14 05:14, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 2:56 PM, Rustom Mody <rustompmody at gmail.com
>>> I don't know about the difference between {} in set theory and Python,
>>> but the multiple uses of () actually boil down to two:
>> In set theory {} makes sets
>> In python {} makes dictionaries
> That's a backward-compatibility issue. Braces in Python meant a
> dictionary before it acquired a set type (at least, so I learned in
> history class - I wasn't using Python back then), so empty braces have
> to continue to mean empty dictionary.

No they didn't have to. With the transition to python3, the developers
could have opted for empty braces to mean an empty set. And if they
wanted a literal for an empty dictionary, they might have chosen {:}.
Backward-compatibility was already broken so that wasn't an argument.

>  I sympathize with the confusion,
> but short of confusing everyone terribly by changing dicts to use
> something other than braces (maybe borrow Pike's mapping notation, ([
> ])??), I don't really see a solution.

Come on. The problem isn't that both set and dictionary literal use
braces. That doesn't seem to be a problem in python3. The only question
was what should {} represent and how do we get an empty collection of
the other kind. If {} had been an empty set, dict() could have been
used for an empty dictionary is {:} had been unacceptable.

-- 
Antoon Pardon



From jeandubois314 at gmail.com  Tue Mar 25 06:26:26 2014
From: jeandubois314 at gmail.com (Jean Dubois)
Date: Tue, 25 Mar 2014 03:26:26 -0700 (PDT)
Subject: [newbie] confusion concerning fetching an element in a 2d-array
Message-ID: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>

I'm confused by the behaviour of the following python-script I wrote:

#!/usr/bin/env python
#I first made a data file 'test.dat' with the following content
#1.0 2 3
#4 5 6.0
#7 8 9
import numpy as np
lines=[line.strip() for line in open('test.dat')]
#convert lines-list to numpy-array
array_lines=np.array(lines)
#fetch element at 2nd row, 2nd column:
print array_lines[1, 1]


When running the script I always get the following error:
IndexError: invalid index

Can anyone here explain me what I am doing wrong and how to fix it?

thanks in advance
jean


From antoon.pardon at rece.vub.ac.be  Tue Mar 25 06:38:38 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 25 Mar 2014 11:38:38 +0100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
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 <roy-66D138.23291924032014@news.panix.com>
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 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
Message-ID: <53315CAE.8030404@rece.vub.ac.be>

On 25-03-14 10:54, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 8:43 PM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> I thought programs were read more than written. So if writing is made
>> a bit more problematic but the result is more readable because we are
>> able to use symbols that are already familiar from other contexts, I
>> would say it is worth it.
> It's a matter of extents. If code is read ten times for every time
> it's written, making it twenty times harder to write and a little bit
> easier to read is still a bad tradeoff.
>
> Also: To what extent IS that symbol familiar from some other context?
> Are you using Python as a programming language, or should you perhaps
> be using a mathematical front-end? Not everything needs to perfectly
> match what anyone from any other context will expect. This is, first
> and foremost, a *programming* language.

So? We do use + -, so why shouldn't we use ? for multiplication. Would
such a use already indicate I should use a mathematical front-end?

When a programming language is borrowing concepts from mathematics,
I see no reason not to borrow the symbols used too.

-- 
Antoon Pardon. 



From amit.khomane at gmail.com  Tue Mar 25 06:52:47 2014
From: amit.khomane at gmail.com (Amit Khomane)
Date: Tue, 25 Mar 2014 03:52:47 -0700 (PDT)
Subject: Have you ever wondered why there are so many flavors of python. This
 post answers all your queries.
Message-ID: <9921c06f-c165-4e0a-8550-531aa5c01c01@googlegroups.com>

http://www.techdarting.com/2014/03/why-different-flavors-of-python.html


From steve+comp.lang.python at pearwood.info  Tue Mar 25 07:01:37 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 11:01:37 GMT
Subject: [newbie] confusion concerning fetching an element in a 2d-array
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
Message-ID: <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 03:26:26 -0700, Jean Dubois wrote:

> I'm confused by the behaviour of the following python-script I wrote:
> 
> #!/usr/bin/env python
> #I first made a data file 'test.dat' with the following content 
> #1.0 2 3
> #4 5 6.0
> #7 8 9
> import numpy as np
> lines=[line.strip() for line in open('test.dat')] 
> #convert lines-list to numpy-array
> array_lines=np.array(lines)
> #fetch element at 2nd row, 2nd column: 
> print array_lines[1, 1]
> 
> 
> When running the script I always get the following error: IndexError:
> invalid index
> 
> Can anyone here explain me what I am doing wrong and how to fix it?

Yes. Inspect the array by printing it, and you'll see that it is a one-
dimensional array, not two, and the entries are strings:


py> import numpy as np
py> # simulate a text file
... data = """1.0 2 3
... 4 5 6.0
... 7 8 9"""
py> lines=[line.strip() for line in data.split('\n')]
py> # convert lines-list to numpy-array
... array_lines = np.array(lines)
py> print array_lines
['1.0 2 3' '4 5 6.0' '7 8 9']


The interactive interpreter is your friend! You never need to guess what 
the problem is, Python has powerful introspection abilities, one of the 
most powerful is also one of the simplest: print. Another powerful tool 
in the interactive interpreter is help().

So, what to do about it? Firstly, convert your string read from a file 
into numbers, then build your array. Here's one way:

py> values = [float(s) for s in data.split()]
py> print values
[1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]
py> array_lines = np.array(values)
py> array_lines = array_lines.reshape(3, 3)
py> print array_lines
[[ 1.  2.  3.]
 [ 4.  5.  6.]
 [ 7.  8.  9.]]


There may be other ways to do this, but that works for me.


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Tue Mar 25 07:12:40 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 22:12:40 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <5331595D.5020008@rece.vub.ac.be>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
 <5331595D.5020008@rece.vub.ac.be>
Message-ID: <CAPTjJmqZ32XBj7KJEeDoQLJx_57VCaaCEjSrVqAKJGHO48Crfw@mail.gmail.com>

On Tue, Mar 25, 2014 at 9:24 PM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> No they didn't have to. With the transition to python3, the developers
> could have opted for empty braces to mean an empty set. And if they
> wanted a literal for an empty dictionary, they might have chosen {:}.
> Backward-compatibility was already broken so that wasn't an argument.

Python 3.0 didn't just say "to Hades with backward compatibility". The
breakage was only in places where it was deemed worthwhile. Changing
the meaning of {} would have only small benefit and would potentially
break a LOT of programs, so the devs were right to not do it.

Python 3 and Python 2 are not, contrary to some people's opinions,
completely different languages.

ChrisA


From steve+comp.lang.python at pearwood.info  Tue Mar 25 07:14:53 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 11:14:53 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
Message-ID: <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 11:38:38 +0100, Antoon Pardon wrote:

> On 25-03-14 10:54, Chris Angelico wrote:
>> On Tue, Mar 25, 2014 at 8:43 PM, Antoon Pardon
>> <antoon.pardon at rece.vub.ac.be> wrote:
>>> I thought programs were read more than written. So if writing is made
>>> a bit more problematic but the result is more readable because we are
>>> able to use symbols that are already familiar from other contexts, I
>>> would say it is worth it.
>> It's a matter of extents. If code is read ten times for every time it's
>> written, making it twenty times harder to write and a little bit easier
>> to read is still a bad tradeoff.
>>
>> Also: To what extent IS that symbol familiar from some other context?
>> Are you using Python as a programming language, or should you perhaps
>> be using a mathematical front-end? Not everything needs to perfectly
>> match what anyone from any other context will expect. This is, first
>> and foremost, a *programming* language.
> 
> So? We do use + -, so why shouldn't we use ? for multiplication. 

I can't find ? on my keyboard!

I tried using x instead, but I got a syntax error:

py> 2x3
  File "<stdin>", line 1
    2x3
      ^
SyntaxError: invalid syntax


> Would
> such a use already indicate I should use a mathematical front-end?
> 
> When a programming language is borrowing concepts from mathematics, I
> see no reason not to borrow the symbols used too.

I'd like to sum the squares of the integers from n=1 to 10. In the old 
Python, I'd write sum(n**2 for n in range(1, 11)), but with the brave new 
world of maths symbols, I'd like to write this:

http://timmurphy.org/examples/summation_large.jpg


How do I enter that, and what text editor should I use?



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From antoon.pardon at rece.vub.ac.be  Tue Mar 25 07:46:14 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 25 Mar 2014 12:46:14 +0100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <53316C86.1090709@rece.vub.ac.be>

On 25-03-14 12:14, Steven D'Aprano wrote:
> On Tue, 25 Mar 2014 11:38:38 +0100, Antoon Pardon wrote:
>
>> On 25-03-14 10:54, Chris Angelico wrote:
>>> On Tue, Mar 25, 2014 at 8:43 PM, Antoon Pardon
>>> <antoon.pardon at rece.vub.ac.be> wrote:
>>>> I thought programs were read more than written. So if writing is made
>>>> a bit more problematic but the result is more readable because we are
>>>> able to use symbols that are already familiar from other contexts, I
>>>> would say it is worth it.
>>> It's a matter of extents. If code is read ten times for every time it's
>>> written, making it twenty times harder to write and a little bit easier
>>> to read is still a bad tradeoff.
>>>
>>> Also: To what extent IS that symbol familiar from some other context?
>>> Are you using Python as a programming language, or should you perhaps
>>> be using a mathematical front-end? Not everything needs to perfectly
>>> match what anyone from any other context will expect. This is, first
>>> and foremost, a *programming* language.
>> So? We do use + -, so why shouldn't we use ? for multiplication. 
> I can't find ? on my keyboard!

Then use an editor that allows you to configure it, so you can
easily use it.

That's the kind of advice that is often enough given here if
some python feature is hard for the tools someone is using.
So why should it be different now?

>> Would
>> such a use already indicate I should use a mathematical front-end?
>>
>> When a programming language is borrowing concepts from mathematics, I
>> see no reason not to borrow the symbols used too.
> I'd like to sum the squares of the integers from n=1 to 10. In the old 
> Python, I'd write sum(n**2 for n in range(1, 11)), but with the brave new 
> world of maths symbols, I'd like to write this:
>
> http://timmurphy.org/examples/summation_large.jpg
>
>
> How do I enter that, and what text editor should I use?

You have a point. Blindly following mathematical notation will not
work, because mathematics often enough uses positional clues that
will be very hard to incorparate in a programming language.

But often enough languages tried to use the symbols that were
available to them. Now that more are, I see little reason for
avoiding there use.

-- 
Antoon Pardon




From antoon.pardon at rece.vub.ac.be  Tue Mar 25 08:07:45 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 25 Mar 2014 13:07:45 +0100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <CAPTjJmqZ32XBj7KJEeDoQLJx_57VCaaCEjSrVqAKJGHO48Crfw@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
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Message-ID: <53317191.7050701@rece.vub.ac.be>

On 25-03-14 12:12, Chris Angelico wrote:

> On Tue, Mar 25, 2014 at 9:24 PM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> No they didn't have to. With the transition to python3, the developers
>> could have opted for empty braces to mean an empty set. And if they
>> wanted a literal for an empty dictionary, they might have chosen {:}.
>> Backward-compatibility was already broken so that wasn't an argument.
> Python 3.0 didn't just say "to Hades with backward compatibility". The
> breakage was only in places where it was deemed worthwhile. Changing
> the meaning of {} would have only small benefit and would potentially
> break a LOT of programs, so the devs were right to not do it.

More programs than those who broke because print was now a function?
Do you think it would have been so problamatic that it couldn't have
been handled by '2to3'?

Maybe breaking backward-compatibility wasn't considered worthwhile,
but that is not the same as stating backward-compatibility was
necessary. And that is how I understood how you stated your claim. 

> Python 3 and Python 2 are not, contrary to some people's opinions,
> completely different languages.

And changing the meaning of {} to now indicate the emppty set, wouldn't
have turned it in a completely different language either.

-- 
Antoon Pardon.




From rustompmody at gmail.com  Tue Mar 25 08:09:20 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 25 Mar 2014 05:09:20 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8514.1395747979.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
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Message-ID: <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>

On Tuesday, March 25, 2014 5:16:14 PM UTC+5:30, Antoon Pardon wrote:
> On 25-03-14 12:14, Steven D'Aprano wrote:

> >> Would
> >> such a use already indicate I should use a mathematical front-end?
> >> When a programming language is borrowing concepts from mathematics, I
> >> see no reason not to borrow the symbols used too.
> > I'd like to sum the squares of the integers from n=1 to 10. In the old 
> > Python, I'd write sum(n**2 for n in range(1, 11)), but with the brave new 
> > world of maths symbols, I'd like to write this:
> > http://timmurphy.org/examples/summation_large.jpg
> > How do I enter that, and what text editor should I use?

> You have a point. Blindly following mathematical notation will not
> work, because mathematics often enough uses positional clues that
> will be very hard to incorparate in a programming language.

Two completely separate questions 

1. Symbols outside of US-104-keyboard/ASCII used for python 
   functions/constants
2. Non-linear math notation

It goes back not just to the first programming languages but to Turing's paper
that what a mathematician can do on 2-d paper can be done on a 1-d 'tape'.
IOW conflating 1 and 2 is not even a poor strawman argument -- Its only 1 that anyone is talking about.

The comparison with APL which had/has at least some pretensions to
being mathematics and also simultaneously being a programming
language are more appropriate

So adding to my earlier list:

> Yes APL is a good example to learn mistakes from
> - being before its time/technology
> - taking a good idea too far
> - assuming that I understand clearly implies so do others

- not taking others' good ideas seriously

Structured programming constructs were hardly known in 1960 when APL was invented.
10 years down they were the rage. APL ignored them -- to its own detriment


> > On Tue, 25 Mar 2014 11:38:38 +0100, Antoon Pardon wrote:
> >> On 25-03-14 10:54, Chris Angelico wrote:
> >>> On Tue, Mar 25, 2014 at 8:43 PM, Antoon Pardon
> >>>> I thought programs were read more than written. So if writing is made
> >>>> a bit more problematic but the result is more readable because we are
> >>>> able to use symbols that are already familiar from other contexts, I
> >>>> would say it is worth it.
> >>> It's a matter of extents. If code is read ten times for every time it's
> >>> written, making it twenty times harder to write and a little bit easier
> >>> to read is still a bad tradeoff.
> >>> Also: To what extent IS that symbol familiar from some other context?
> >>> Are you using Python as a programming language, or should you perhaps
> >>> be using a mathematical front-end? Not everything needs to perfectly
> >>> match what anyone from any other context will expect. This is, first
> >>> and foremost, a *programming* language.
> >> So? We do use + -, so why shouldn't we use ? for multiplication. 
> > I can't find ? on my keyboard!

> Then use an editor that allows you to configure it, so you can
> easily use it.

> That's the kind of advice that is often enough given here if
> some python feature is hard for the tools someone is using.
> So why should it be different now?

> But often enough languages tried to use the symbols that were
> available to them. Now that more are, I see little reason for
> avoiding there use.

I am reminded that when Unix first came out, some of both the early
adoption as well as the early pooh-pooh-ing was around the
novelty/stupidity of using lower-case in programming






From roy at panix.com  Tue Mar 25 08:21:19 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 25 Mar 2014 08:21:19 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
 <mailman.8511.1395743071.18130.python-list@python.org>
Message-ID: <roy-333172.08211925032014@news.panix.com>

In article <mailman.8511.1395743071.18130.python-list at python.org>,
 Antoon Pardon <antoon.pardon at rece.vub.ac.be> wrote:

> Come on. The problem isn't that both set and dictionary literal use
> braces. That doesn't seem to be a problem in python3. The only question
> was what should {} represent and how do we get an empty collection of
> the other kind. If {} had been an empty set, dict() could have been
> used for an empty dictionary is {:} had been unacceptable.

By analogy to tuples, it could have been {,}.


From roy at panix.com  Tue Mar 25 08:24:12 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 25 Mar 2014 08:24:12 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
Message-ID: <roy-841DFA.08241225032014@news.panix.com>

In article <lgquvt$b7t$1 at speranza.aioe.org>,
 Mark H Harris <harrismh777 at gmail.com> wrote:

> On 3/24/14 10:51 PM, Chris Angelico wrote:
> > Supporting both may look tempting, but you effectively create two ways
> > of spelling the exact same thing; it'd be like C's trigraphs. Do you
> > know what ??= is,
> 
> This was a fit for me, back in the day IBM (system36 & system38). When 
> we started supporting the C compiler (ha!) and non of our 5250 terminals 
> could provide the C punctuation we take for granted today--- so we 
> invented tri-graphs for { and } and others. It was a hoot.

Our ASR-33s didn't have { and }, so we used \( and \).  To be honest, I 
don't remember if the c compiler understood those, or if it was mapped 
at the tty driver level.


From roy at panix.com  Tue Mar 25 08:35:02 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 25 Mar 2014 08:35:02 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
Message-ID: <roy-38C75A.08350225032014@news.panix.com>

In article <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e at googlegroups.com>,
 Rustom Mody <rustompmody at gmail.com> wrote:

> And Chris is right in (rephrasing) we may have unicode-happy OSes and
> languages. We cant reasonably have unicode-happy keyboards.
> [What would a million-key keyboard look like? Lets leave the cost aside...]

In a true unicode environment, the input device may be nothing like our 
current keyboards.

Star Trek has been amazingly accurate about it's predictions of the 
future.  Doors that open automatically as you approach them are now 
routine.  One thing they messed up on was mobile devices; they assumed 
tricorders and communicators would be separate devices, when in reality 
our phones now perform both functions.  Today's 3-d printers are giving 
replicators a run for their money.  Some people still get bent out of 
shape when a white man kisses a black woman, but we're working on that.

When's the last time you saw somebody typing commands to a computer on 
Star Trek?


From roy at panix.com  Tue Mar 25 08:36:59 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 25 Mar 2014 08:36:59 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <lgr4hf$mbd$1@speranza.aioe.org>
 <mailman.8495.1395726527.18130.python-list@python.org>
 <lgr5pq$olp$1@speranza.aioe.org>
Message-ID: <roy-25AA1A.08365925032014@news.panix.com>

In article <lgr5pq$olp$1 at speranza.aioe.org>,
 Mark H Harris <harrismh777 at gmail.com> wrote:

> (we're on one tiny planet, you know?)

Speak for yourself.


From rosuav at gmail.com  Tue Mar 25 08:45:16 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 25 Mar 2014 23:45:16 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53317191.7050701@rece.vub.ac.be>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
 <5331595D.5020008@rece.vub.ac.be>
 <CAPTjJmqZ32XBj7KJEeDoQLJx_57VCaaCEjSrVqAKJGHO48Crfw@mail.gmail.com>
 <53317191.7050701@rece.vub.ac.be>
Message-ID: <CAPTjJmpNZc3=2X-4RV4K94D5Mn0QdAOU_81g8jKz-Pjh=gYF+w@mail.gmail.com>

On Tue, Mar 25, 2014 at 11:07 PM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> On 25-03-14 12:12, Chris Angelico wrote:
>
>> On Tue, Mar 25, 2014 at 9:24 PM, Antoon Pardon
>> <antoon.pardon at rece.vub.ac.be> wrote:
>>> No they didn't have to. With the transition to python3, the developers
>>> could have opted for empty braces to mean an empty set. And if they
>>> wanted a literal for an empty dictionary, they might have chosen {:}.
>>> Backward-compatibility was already broken so that wasn't an argument.
>> Python 3.0 didn't just say "to Hades with backward compatibility". The
>> breakage was only in places where it was deemed worthwhile. Changing
>> the meaning of {} would have only small benefit and would potentially
>> break a LOT of programs, so the devs were right to not do it.
>
> More programs than those who broke because print was now a function?
> Do you think it would have been so problamatic that it couldn't have
> been handled by '2to3'?

It makes the same notation mean different things, in ways that are
hard to render clearly. You can write a Py3 program and put this at
the top for Py2:

try:
    input = raw_input
    range = xrange
except NameError:
    # We're running on Python 3
    pass

But you can't do the same for braces. You'd have to eschew *both*
literal-ish notations and use explicit constructors everywhere. Not
clean.

ChrisA


From rustompmody at gmail.com  Tue Mar 25 08:53:45 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 25 Mar 2014 05:53:45 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <roy-25AA1A.08365925032014@news.panix.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
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 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
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 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <lgr4hf$mbd$1@speranza.aioe.org>
 <mailman.8495.1395726527.18130.python-list@python.org>
 <lgr5pq$olp$1@speranza.aioe.org> <roy-25AA1A.08365925032014@news.panix.com>
Message-ID: <2f646b95-7d73-4a60-a222-96fa3cd219df@googlegroups.com>

On Tuesday, March 25, 2014 4:08:38 PM UTC+5:30, Antoon Pardon wrote:
> So? We do use + -, so why shouldn't we use ? for multiplication. Would
> such a use already indicate I should use a mathematical front-end?

> When a programming language is borrowing concepts from mathematics,
> I see no reason not to borrow the symbols used too.

Well...
Matters of taste are personal, touchy-feely things and not easily 
explainable.

Some of mine:
* for multiply does not bother me; ** for power for some reason does.
Even though the only standard math notation is non-linear and is off-limits

'and' bothers me slightly (maybe because I was brought up on Pascal?)
'&&' less (and then C)
? is of course best (I am a Dijkstra fan)
[But then Dijkstra would probably roll over and over in his grave at
short-circuit 'and'. Non-commutative?!?! Blasphemy!]

? for some reason seems inappropriate
(some vague recollection that its an only English; Europeans dont use it??)

And if we had hyphen '?' distinguished from minus '-' then we could have lispish
names like call?with?current?continuation properly spelt.
And then generations of programmers will thank us for increasing their
debugging overtime!! 


From antoon.pardon at rece.vub.ac.be  Tue Mar 25 09:07:02 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 25 Mar 2014 14:07:02 +0100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <CAPTjJmpNZc3=2X-4RV4K94D5Mn0QdAOU_81g8jKz-Pjh=gYF+w@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
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Message-ID: <53317F76.6000501@rece.vub.ac.be>

On 25-03-14 13:45, Chris Angelico wrote:

> It makes the same notation mean different things, in ways that are
> hard to render clearly. You can write a Py3 program and put this at
> the top for Py2:
>
> try:
>     input = raw_input
>     range = xrange
> except NameError:
>     # We're running on Python 3
>     pass
>
> But you can't do the same for braces. You'd have to eschew *both*
> literal-ish notations and use explicit constructors everywhere. Not
> clean.

What about it, is not clean? I understand that you prefer it how
it worked out. That is fine by me. But that doesn't make the
alternative unclean. Is having to write "set()" unclean somehow
when you need an empty set? I wouldn't think so. So I see no
reason why having to write "dict()" when you need an empty dictionary
wouldn't be clean.

Nor would it be unclean, when you have to write somethings a bit
differently when you want your program to be compatible both
with python2 and python3.

You will also need to prefix all your (unicode) strings with u and
all your byte strings with b. And probably some more stuff if you
want to avoid some pitfalls.

-- 
Antoon Pardon




From rustompmody at gmail.com  Tue Mar 25 09:07:33 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 25 Mar 2014 06:07:33 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8516.1395751525.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
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Message-ID: <38bbeeeb-8e3b-47fa-a5e7-e3ab40432fb4@googlegroups.com>

On Tuesday, March 25, 2014 6:15:16 PM UTC+5:30, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 11:07 PM, Antoon Pardon
> > On 25-03-14 12:12, Chris Angelico wrote:
> >> On Tue, Mar 25, 2014 at 9:24 PM, Antoon Pardon
> >>> No they didn't have to. With the transition to python3, the developers
> >>> could have opted for empty braces to mean an empty set. And if they
> >>> wanted a literal for an empty dictionary, they might have chosen {:}.
> >>> Backward-compatibility was already broken so that wasn't an argument.
> >> Python 3.0 didn't just say "to Hades with backward compatibility". The
> >> breakage was only in places where it was deemed worthwhile. Changing
> >> the meaning of {} would have only small benefit and would potentially
> >> break a LOT of programs, so the devs were right to not do it.
> > More programs than those who broke because print was now a function?
> > Do you think it would have been so problamatic that it couldn't have
> > been handled by '2to3'?

> It makes the same notation mean different things, in ways that are
> hard to render clearly. You can write a Py3 program and put this at
> the top for Py2:

> try:
>     input = raw_input
>     range = xrange
> except NameError:
>     # We're running on Python 3
>     pass

> But you can't do the same for braces. You'd have to eschew *both*
> literal-ish notations and use explicit constructors everywhere. Not
> clean.

What you are answering (2) is somewhat different from what Anton is asking (1).

1. Use a tool (2to3 inspired) to help move programs to the the new lexicon
2. Use 2to3 to (help) write code that is backward-compatible 

It is an invariable given that when heavily compatible code is desired, the 
programmer gets the worst of all worlds


From rosuav at gmail.com  Tue Mar 25 09:13:36 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 26 Mar 2014 00:13:36 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <roy-38C75A.08350225032014@news.panix.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
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Message-ID: <CAPTjJmpTg6ni1Rq+7NZeZ7HwpYu1s0O0jVWxWrU_yhEEPQp6BQ@mail.gmail.com>

On Tue, Mar 25, 2014 at 11:35 PM, Roy Smith <roy at panix.com> wrote:
> When's the last time you saw somebody typing commands to a computer on
> Star Trek?

That's more like what comes up in Cars 2. "It's voice activated... but
then, everything is these days!"

ChrisA


From matt.newville at gmail.com  Tue Mar 25 09:34:43 2014
From: matt.newville at gmail.com (matt.newville at gmail.com)
Date: Tue, 25 Mar 2014 06:34:43 -0700 (PDT)
Subject: advice on sub-classing multiprocessing.Process and
 multiprocessing.BaseManager
In-Reply-To: <mailman.8484.1395719089.18130.python-list@python.org>
References: <CA+7ESbr9i6VEO709jPF8ghoPRsUggqBrCEJhoXBn7LK6wYSA+w@mail.gmail.com>
 <mailman.8474.1395707125.18130.python-list@python.org>
 <80cf8fb7-d0c5-43a9-bc6f-c61ce6214f98@googlegroups.com>
 <mailman.8484.1395719089.18130.python-list@python.org>
Message-ID: <8d59e3a4-e6af-4633-869b-53568f6091cd@googlegroups.com>

ChrisA -

>> I wasn't really asking "is multiprocessing appropriate?" but whether
>> there was a cleaner way to subclass multiprocessing.BaseManager() to 
>> use a subclass of Process().  I can believe the answer is No, but 
>> thought I'd ask.
> 
> I've never subclassed BaseManager like this. It might be simpler to
> spin off one or more workers and not have them do any network
> communication at all; that way, you don't need to worry about the
> cache. Set up a process tree with one at the top doing only networking
> and process management (so it's always fast), and then use a
> multiprocessing.Queue or somesuch to pass info to a subprocess and
> back. Then your global connection state is all stored within the top
> process, and none of the others need care about it. You might have a
> bit of extra effort to pass info back to the parent rather than simply
> writing it to the connection, but that's a common requirement in other
> areas (eg GUI handling - it's common to push all GUI manipulation onto
> the main thread), so it's a common enough model.
> 
> But if subclassing and tweaking is the easiest way, and if you don't
> mind your solution being potentially fragile (which subclassing like
> that is), then you could look into monkey-patching Process. Inject
> your code into it and then use the original. It's not perfect, but it
> may turn out easier than the "subclass everything" technique.
> 
> ChrisA

Thanks, I agree that restricting network communications to a parent process would be a good recommended solution, but it's hard to enforce and easy to forget such a recommendation.  It seems better to provide lightweight library-specific subclasses of Process (and Pool) and explaining why they should be used.  This library (pyepics) already does similar things for interaction with other libraries (notably providing decorators to avoid issues with wxPython). 

Monkey-patching multiprocessing.Process seems more fragile than subclassing it.  It turned out that multiprocessing.pool.Pool was also very easy to subclass.  But cleanly subclassing the Managers in multiprocessing.managers look much harder.  I'm not sure if this is intentional or not, or if it should be filed as an issue for multiprocessing.   For now, I'm willing to say that the multiprocessing managers are not yet available with the pyepics library.

Thanks again,

--Matt



From steve+comp.lang.python at pearwood.info  Tue Mar 25 09:36:36 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 13:36:36 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
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Message-ID: <53318664$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 08:21:19 -0400, Roy Smith wrote:

> In article <mailman.8511.1395743071.18130.python-list at python.org>,
>  Antoon Pardon <antoon.pardon at rece.vub.ac.be> wrote:
> 
>> Come on. The problem isn't that both set and dictionary literal use
>> braces. That doesn't seem to be a problem in python3. The only question
>> was what should {} represent and how do we get an empty collection of
>> the other kind. If {} had been an empty set, dict() could have been
>> used for an empty dictionary is {:} had been unacceptable.
> 
> By analogy to tuples, it could have been {,}.

An empty tuple is (), not (,). {,} is just making up random syntax almost 
unrelated to anything else. One might as well used {?} or {+}.

If Python 3 had introduced {} to mean the empty set, I *guarantee* that 
right now people would be arguing that "Python 3 could have used {} for 
the empty dict, and used set() for the empty set" -- and very likely the 
same people now arguing the opposite.

Yes, Python could have changed the meaning of {} to mean the empty set. 
But you know what? The empty set is not that important. Sets are not 
fundamental to Python. Python didn't even have sets until 2.3, and at 
first they were just a standard library module, not even built-in. Dicts, 
on the other hand, are fundamental to Python. They are used everywhere. 
Python is, in a very real sense, built on dicts, not sets. You can 
implement sets starting from dicts, but not the other way around: dicts 
are more fundamental than sets.

I'm sure it is awfully impressive that mathematicians can derive the laws 
of integer maths starting only from the empty set ?, but as far as 
programming goes that's not a very useful thing. Dicts are much more 
important, and they are much more commonly used.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From antoon.pardon at rece.vub.ac.be  Tue Mar 25 09:43:09 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 25 Mar 2014 14:43:09 +0100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <2f646b95-7d73-4a60-a222-96fa3cd219df@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
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 <2f646b95-7d73-4a60-a222-96fa3cd219df@googlegroups.com>
Message-ID: <533187ED.7060509@rece.vub.ac.be>

On 25-03-14 13:53, Rustom Mody wrote:
> On Tuesday, March 25, 2014 4:08:38 PM UTC+5:30, Antoon Pardon wrote:
>> So? We do use + -, so why shouldn't we use ? for multiplication. Would
>> such a use already indicate I should use a mathematical front-end?
>> When a programming language is borrowing concepts from mathematics,
>> I see no reason not to borrow the symbols used too.
> Well...
> Matters of taste are personal, touchy-feely things and not easily 
> explainable.
>
> Some of mine:
> * for multiply does not bother me; ** for power for some reason does.
> Even though the only standard math notation is non-linear and is off-limits
>
> 'and' bothers me slightly (maybe because I was brought up on Pascal?)
> '&&' less (and then C)
> ? is of course best (I am a Dijkstra fan)
> [But then Dijkstra would probably roll over and over in his grave at
> short-circuit 'and'. Non-commutative?!?! Blasphemy!]
>
> ? for some reason seems inappropriate
> (some vague recollection that its an only English; Europeans dont use it??)

> It doesn't bother me. IIRC in primary school before fractions were introduced,
> a colon was used to indicate division.
>
> And if we had hyphen '?' distinguished from minus '-' then we could have lispish
> names like call?with?current?continuation properly spelt.
> And then generations of programmers will thank us for increasing their
> debugging overtime!! 
>
Sure we could argue some partciculars. Personnaly I would prefer an up-arrow
for exponentiation.

IMO the advantage would be mainly in allowing more disambiguity. So that if
you as a programmer think about something as an operator, you are not obligated
to somehow force it into the mold of + - * / % //.

If ? would have been used for attribute access, then we could just write 
5?to_bytes(4, "little") without having to consider that the lexer would
try to interpret it as a floating point.

And maybe ? could have been used for concatenation. Which would mean that
if you had a class whose instances could both be added and concatenated,
you could implement both as an operator.

Finally, I think I would prefer the middle dot ? for lispish names so
we would have call?with?current?continuation.




From jeandubois314 at gmail.com  Tue Mar 25 09:47:23 2014
From: jeandubois314 at gmail.com (Jean Dubois)
Date: Tue, 25 Mar 2014 06:47:23 -0700 (PDT)
Subject: [newbie] confusion concerning fetching an element in a 2d-array
In-Reply-To: <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>

Op dinsdag 25 maart 2014 12:01:37 UTC+1 schreef Steven D'Aprano:
> On Tue, 25 Mar 2014 03:26:26 -0700, Jean Dubois wrote:
>
> > I'm confused by the behaviour of the following python-script I wrote:
> > 
> > #!/usr/bin/env python
> > #I first made a data file 'test.dat' with the following content 
> > #1.0 2 3
> > #4 5 6.0
> > #7 8 9
> > import numpy as np
> > lines=[line.strip() for line in open('test.dat')] 
> > #convert lines-list to numpy-array
> > array_lines=np.array(lines)
> > #fetch element at 2nd row, 2nd column: 
> > print array_lines[1, 1]
> > 
> > 
> > When running the script I always get the following error: IndexError:
> > invalid index
> > 
> > Can anyone here explain me what I am doing wrong and how to fix it?
>
> Yes. Inspect the array by printing it, and you'll see that it is a one-
> dimensional array, not two, and the entries are strings:
>
>
> py> import numpy as np
> py> # simulate a text file
> ... data = """1.0 2 3
> ... 4 5 6.0
> ... 7 8 9"""
> py> lines=[line.strip() for line in data.split('\n')]
> py> # convert lines-list to numpy-array
> ... array_lines = np.array(lines)
> py> print array_lines
> ['1.0 2 3' '4 5 6.0' '7 8 9']
>
>
> The interactive interpreter is your friend! You never need to guess what 
> the problem is, Python has powerful introspection abilities, one of the 
> most powerful is also one of the simplest: print. Another powerful tool 
> in the interactive interpreter is help().
>
> So, what to do about it? Firstly, convert your string read from a file 
> into numbers, then build your array. Here's one way:
>
> py> values = [float(s) for s in data.split()]
> py> print values
> [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]
> py> array_lines = np.array(values)
> py> array_lines = array_lines.reshape(3, 3)
> py> print array_lines
> [[ 1.  2.  3.]
>  [ 4.  5.  6.]
>  [ 7.  8.  9.]]
>
Dear Steve,
Thanks for answering my question but unfortunately now I'm totally
confused. 
Above I see parts from different programs which I can't
assemble together to one working program (I really tried hard).
Can I tell from your comment I shouldn't use numpy?
I also don't see how to get the value an element specified by (row,
column) from a numpy_array like "array_lines" in my original code

All I need is a little python-example reading a file with e.g. three lines
with three numbers per line and putting those numbers  as floats in a
3x3-numpy_array, then selecting an element from that numpy_array using
it's row and column-number.

thanks in advance and kind regards,
jean






From rosuav at gmail.com  Tue Mar 25 09:50:15 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 26 Mar 2014 00:50:15 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <38bbeeeb-8e3b-47fa-a5e7-e3ab40432fb4@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <5331595D.5020008@rece.vub.ac.be>
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 <mailman.8516.1395751525.18130.python-list@python.org>
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Message-ID: <CAPTjJmrKjOK9XE+p+nUSFz0+enN_XCjkup44nWTQ7jRHAxQ-dw@mail.gmail.com>

On Wed, Mar 26, 2014 at 12:07 AM, Rustom Mody <rustompmody at gmail.com> wrote:
> What you are answering (2) is somewhat different from what Anton is asking (1).
>
> 1. Use a tool (2to3 inspired) to help move programs to the the new lexicon
> 2. Use 2to3 to (help) write code that is backward-compatible
>
> It is an invariable given that when heavily compatible code is desired, the
> programmer gets the worst of all worlds

That is true. But writing cross-compatible code IS important, and that
means that backward compatibility is still important, and that
breaking it is a cost - which was my original point. Other
non-backward-compatible changes at 3.0 are not justification to
arbitrarily change the meanings of syntactic elements. Don't forget,
even if you're not writing a single file that gets executed unmodified
on two versions, you still have to worry about your brain changing
gear.

ChrisA


From rustompmody at gmail.com  Tue Mar 25 09:52:21 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 25 Mar 2014 06:52:21 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8519.1395754991.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
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 <lgquvt$b7t$1@speranza.aioe.org>
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 <lgr5pq$olp$1@speranza.aioe.org> <roy-25AA1A.08365925032014@news.panix.com>
 <2f646b95-7d73-4a60-a222-96fa3cd219df@googlegroups.com>
 <mailman.8519.1395754991.18130.python-list@python.org>
Message-ID: <09508435-1b9b-424b-a052-b9f69de17ff6@googlegroups.com>

On Tuesday, March 25, 2014 7:13:09 PM UTC+5:30, Antoon Pardon wrote:
> On 25-03-14 13:53, Rustom Mody wrote:
> > On Tuesday, March 25, 2014 4:08:38 PM UTC+5:30, Antoon Pardon wrote:
> >> So? We do use + -, so why shouldn't we use ? for multiplication. Would
> >> such a use already indicate I should use a mathematical front-end?
> >> When a programming language is borrowing concepts from mathematics,
> >> I see no reason not to borrow the symbols used too.
> > Well...
> > Matters of taste are personal, touchy-feely things and not easily 
> > explainable.
> > Some of mine:
> > * for multiply does not bother me; ** for power for some reason does.
> > Even though the only standard math notation is non-linear and is off-limits
> > 'and' bothers me slightly (maybe because I was brought up on Pascal?)
> > '&&' less (and then C)
> > ? is of course best (I am a Dijkstra fan)
> > [But then Dijkstra would probably roll over and over in his grave at
> > short-circuit 'and'. Non-commutative?!?! Blasphemy!]
> > ? for some reason seems inappropriate
> > (some vague recollection that its an only English; Europeans dont use it??)

> > It doesn't bother me. IIRC in primary school before fractions were introduced,
> > a colon was used to indicate division.
> > And if we had hyphen '?' distinguished from minus '-' then we could have lispish
> > names like call?with?current?continuation properly spelt.
> > And then generations of programmers will thank us for increasing their
> > debugging overtime!! 
> Sure we could argue some partciculars. Personnaly I would prefer an up-arrow
> for exponentiation.

Ok

> IMO the advantage would be mainly in allowing more disambiguity. So that if
> you as a programmer think about something as an operator, you are not obligated
> to somehow force it into the mold of + - * / % //.

> If ? would have been used for attribute access, then we could just write 

Nice

> 5?to_bytes(4, "little") without having to consider that the lexer would
> try to interpret it as a floating point.

> And maybe ? could have been used for concatenation. Which would mean that

Super! Anything but a (randomly overloaded) +!

> if you had a class whose instances could both be added and concatenated,
> you could implement both as an operator.

> Finally, I think I would prefer the middle dot ? for lispish names so
> we would have call?with?current?continuation.

A bit unreadable out here but not too bad


From rosuav at gmail.com  Tue Mar 25 09:56:47 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 26 Mar 2014 00:56:47 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <533187ED.7060509@rece.vub.ac.be>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
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 <roy-66D138.23291924032014@news.panix.com>
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Message-ID: <CAPTjJmrLtDwgpN-LV_dZM7USc66h+S3r0gFXF7itiMfDd4QPJw@mail.gmail.com>

On Wed, Mar 26, 2014 at 12:43 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
>> It doesn't bother me. IIRC in primary school before fractions were introduced,
>> a colon was used to indicate division.

The way I learned it, a colon was for a ratio, and a horizontal line
was for a fraction. Both of them effectively indicate division, but
with a distinct difference. If you have four red objects and two blue
ones, the ratio of red to blue is 4 : 2 or 2 : 1, but the fraction
(proportion) that are red is 4 / 6 or 2 / 3.

ChrisA


From rosuav at gmail.com  Tue Mar 25 10:00:52 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 26 Mar 2014 01:00:52 +1100
Subject: advice on sub-classing multiprocessing.Process and
 multiprocessing.BaseManager
In-Reply-To: <8d59e3a4-e6af-4633-869b-53568f6091cd@googlegroups.com>
References: <CA+7ESbr9i6VEO709jPF8ghoPRsUggqBrCEJhoXBn7LK6wYSA+w@mail.gmail.com>
 <mailman.8474.1395707125.18130.python-list@python.org>
 <80cf8fb7-d0c5-43a9-bc6f-c61ce6214f98@googlegroups.com>
 <mailman.8484.1395719089.18130.python-list@python.org>
 <8d59e3a4-e6af-4633-869b-53568f6091cd@googlegroups.com>
Message-ID: <CAPTjJmoAUjQ3hq7fi_YfEcj7TYXBOXu7A+T+uFJ+ANfuezi1pA@mail.gmail.com>

On Wed, Mar 26, 2014 at 12:34 AM,  <matt.newville at gmail.com> wrote:
> Monkey-patching multiprocessing.Process seems more fragile than subclassing it.  It turned out that multiprocessing.pool.Pool was also very easy to subclass.  But cleanly subclassing the Managers in multiprocessing.managers look much harder.  I'm not sure if this is intentional or not, or if it should be filed as an issue for multiprocessing.   For now, I'm willing to say that the multiprocessing managers are not yet available with the pyepics library.
>

Subclassing is actually more fragile than you might think. As you've
found, you need to fidget with more and more classes to make your
change "stick", and also, any small change to implementation details
in the superclass could suddenly break things. It's not really any
safer than monkeypatching, despite all the OO fanatics saying how easy
it is to rework by subclassing. At least when you monkeypatch, you
*know* you're fiddling with internals.

ChrisA


From antoon.pardon at rece.vub.ac.be  Tue Mar 25 10:01:09 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 25 Mar 2014 15:01:09 +0100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53318664$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
 <mailman.8511.1395743071.18130.python-list@python.org>
 <roy-333172.08211925032014@news.panix.com>
 <53318664$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <53318C25.2010103@rece.vub.ac.be>

On 25-03-14 14:36, Steven D'Aprano wrote:
> On Tue, 25 Mar 2014 08:21:19 -0400, Roy Smith wrote:
>
>> In article <mailman.8511.1395743071.18130.python-list at python.org>,
>>  Antoon Pardon <antoon.pardon at rece.vub.ac.be> wrote:
>>
>>> Come on. The problem isn't that both set and dictionary literal use
>>> braces. That doesn't seem to be a problem in python3. The only question
>>> was what should {} represent and how do we get an empty collection of
>>> the other kind. If {} had been an empty set, dict() could have been
>>> used for an empty dictionary is {:} had been unacceptable.
>> By analogy to tuples, it could have been {,}.
> An empty tuple is (), not (,). {,} is just making up random syntax almost 
> unrelated to anything else. One might as well used {?} or {+}.
>
> If Python 3 had introduced {} to mean the empty set, I *guarantee* that 
> right now people would be arguing that "Python 3 could have used {} for 
> the empty dict, and used set() for the empty set" -- and very likely the 
> same people now arguing the opposite.

Sure and other people would have defended that choice and very likely
the same people that are defending the current choice now. What is 
your point?

> Yes, Python could have changed the meaning of {} to mean the empty set. 
> But you know what? The empty set is not that important. Sets are not 
> fundamental to Python. Python didn't even have sets until 2.3, and at 
> first they were just a standard library module, not even built-in. Dicts, 
> on the other hand, are fundamental to Python. They are used everywhere. 
> Python is, in a very real sense, built on dicts, not sets. You can 
> implement sets starting from dicts, but not the other way around: dicts 
> are more fundamental than sets.

Fine, dicts are more fundamental. I just don't see that as such a big
argument against using a different literal for the empty dictionary
than was used in python2 and using {} to indicate the empty set. I
would have preferred it that way, but I don't consider it a big deal.

I just consider the arguments weak for those who seem to argue that
using {} for an empty dictionary in python3 was as good as unavoidable.

-- 
Antoon Pardon




From rustompmody at gmail.com  Tue Mar 25 10:08:11 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 25 Mar 2014 07:08:11 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8521.1395755810.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
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 <lgr4hf$mbd$1@speranza.aioe.org>
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 <lgr5pq$olp$1@speranza.aioe.org> <roy-25AA1A.08365925032014@news.panix.com>
 <2f646b95-7d73-4a60-a222-96fa3cd219df@googlegroups.com>
 <533187ED.7060509@rece.vub.ac.be>
 <mailman.8521.1395755810.18130.python-list@python.org>
Message-ID: <32d77df0-c4b5-4096-84c6-af0b4de12574@googlegroups.com>

On Tuesday, March 25, 2014 7:26:47 PM UTC+5:30, Chris Angelico wrote:
> On Wed, Mar 26, 2014 at 12:43 AM, Antoon Pardon
> >> It doesn't bother me. IIRC in primary school before fractions were introduced,
> >> a colon was used to indicate division.

> The way I learned it, a colon was for a ratio, and a horizontal line
> was for a fraction. Both of them effectively indicate division, but
> with a distinct difference. If you have four red objects and two blue
> ones, the ratio of red to blue is 4 : 2 or 2 : 1, but the fraction
> (proportion) that are red is 4 / 6 or 2 / 3.


http://www.unicode.org/mail-arch/unicode-ml/y2012-m07/0053.html



From steve+comp.lang.python at pearwood.info  Tue Mar 25 10:13:31 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 14:13:31 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <roy-38C75A.08350225032014@news.panix.com>
Message-ID: <53318f0b$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 08:35:02 -0400, Roy Smith wrote:

> In article <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e at googlegroups.com>,
>  Rustom Mody <rustompmody at gmail.com> wrote:
> 
>> And Chris is right in (rephrasing) we may have unicode-happy OSes and
>> languages. We cant reasonably have unicode-happy keyboards. [What would
>> a million-key keyboard look like? Lets leave the cost aside...]
> 
> In a true unicode environment, the input device may be nothing like our
> current keyboards.

I doubt it. I expect that they will be based on our current keyboards.


> Star Trek has been amazingly accurate about it's predictions of the
> future.

O_o


> Doors that open automatically as you approach them are now
> routine.  

It's very easy to predict things that have already happened. Star Trek 
was created in 1966. The electric automatic door was invented in 1954 by 
Lew Hewitt and Dee Horton. (Well, actually the first automatic door was 
built in the 1st century CE by Heron of Alexandra, but that's another 
story.)

Electric doors may be common in some commercial premises, such as 
shopping centres and some office buildings, but I wouldn't call them 
routine.


> One thing they messed up on was mobile devices; they assumed
> tricorders and communicators would be separate devices, when in reality
> our phones now perform both functions.  Today's 3-d printers are giving
> replicators a run for their money.

Today's 3D printers are to replicators what a stone axe is to a full wood-
working tool shop.


>  Some people still get bent out of
> shape when a white man kisses a black woman, but we're working on that.
> 
> When's the last time you saw somebody typing commands to a computer on
> Star Trek?

1986, when I last saw Star Trek IV.

The Star Trek universe also predicts that money will be obsolete. How's 
that prediction working out?




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Tue Mar 25 10:23:23 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 14:23:23 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <lgr4hf$mbd$1@speranza.aioe.org>
 <mailman.8495.1395726527.18130.python-list@python.org>
 <lgr5pq$olp$1@speranza.aioe.org> <roy-25AA1A.08365925032014@news.panix.com>
 <2f646b95-7d73-4a60-a222-96fa3cd219df@googlegroups.com>
Message-ID: <5331915b$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 05:53:45 -0700, Rustom Mody wrote:

> And if we had hyphen '?' distinguished from minus '-' then we could have
> lispish names like call?with?current?continuation properly spelt. And
> then generations of programmers will thank us for increasing their
> debugging overtime!!

:-)


Full Unicode support in a language is, alas, a double-edged sword. While 
it has advantages, it also has disadvantages.

py> ? = 1
py> A = ? + 1
py> assert A == ?
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AssertionError


While I can see the appeal of certain Unicode symbols, I really wouldn't 
like to have to deal with code that looks like this:

x?2*y+?e**3?z?(x+1)?y?w

If I wanted line-noise, I know where to get Perl :-)



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From davea at davea.name  Tue Mar 25 10:42:13 2014
From: davea at davea.name (Dave Angel)
Date: Tue, 25 Mar 2014 10:42:13 -0400 (EDT)
Subject: [newbie] confusion concerning fetching an element in a 2d-array
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
Message-ID: <lgs4a4$qsh$1@ger.gmane.org>

 Jean Dubois <jeandubois314 at gmail.com> Wrote in message:
> Op dinsdag 25 maart 2014 12:01:37 UTC+1 schreef Steven D'Aprano:

>>
>> py> values = [float(s) for s in data.split()]
>> py> print values
>> [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]
>> py> array_lines = np.array(values)
>> py> array_lines = array_lines.reshape(3, 3)
>> py> print array_lines
>> [[ 1.  2.  3.]
>>  [ 4.  5.  6.]
>>  [ 7.  8.  9.]]
>>
> Dear Steve,
> Thanks for answering my question but unfortunately now I'm totally
> confused. 
> Above I see parts from different programs which I can't
> assemble together to one working program (I really tried hard).
> Can I tell from your comment I shouldn't use numpy?
> I also don't see how to get the value an element specified by (row,
> column) from a numpy_array like "array_lines" in my original code

I don't use numpy,  but I thought Steven's description was clear
 enough.

Your problem was not the extraction,  but the creation of the
 array.  Use print to prove that to yourself. 

> 
> All I need is a little python-example reading a file with e.g. three lines
> with three numbers per line and putting those numbers  as floats in a
> 3x3-numpy_array, then selecting an element from that numpy_array using
> it's row and column-number.

If your instructor wanted you to copy examples,  he would have
 given you one.

First write some code to split and convert each line into floats.
 You don't even try that in your original.  Then do that in a
 loop. Now you have all the floats in one list or array. I presume
 that it's two dimensional.  Use print to check.  If it's not, 
 you'll have to either post process it with a reshape method,  or
 change the way you accumulate it. I can't help with the latter.
 



-- 
DaveA



From rosuav at gmail.com  Tue Mar 25 10:37:51 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 26 Mar 2014 01:37:51 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53318f0b$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <roy-38C75A.08350225032014@news.panix.com>
 <53318f0b$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqLp-WZgXC8V5ppX8XXehcZbLs2+ep+G0tmZA0mF06gcw@mail.gmail.com>

On Wed, Mar 26, 2014 at 1:13 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Tue, 25 Mar 2014 08:35:02 -0400, Roy Smith wrote:
>
>> In article <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e at googlegroups.com>,
>>  Rustom Mody <rustompmody at gmail.com> wrote:
>>
>>> And Chris is right in (rephrasing) we may have unicode-happy OSes and
>>> languages. We cant reasonably have unicode-happy keyboards. [What would
>>> a million-key keyboard look like? Lets leave the cost aside...]
>>
>> In a true unicode environment, the input device may be nothing like our
>> current keyboards.
>
> I doubt it. I expect that they will be based on our current keyboards.

Rule #0 of any voice-activated system: The command word "Console" MUST
summon a terminal window, and make available a keyboard and screen on
which to use it. This console MAY demand authentication (via typed
password) before operating.

I don't know if that's written anywhere, but it ought to be. It should
be as fundamental as Asimov's laws of robotics. That one simple rule
would improve scifi like "Eureka" no end. Hey look, we have a rogue
AI... "CONSOLE!"... hey look, we have a rogue AI on a system that's
now powered off. Crisis averted, now go solve the problem in a mundane
and not very TV-friendly way...

>> Star Trek has been amazingly accurate about it's predictions of the
>> future.
>
> O_o

I like the Scott Adams take on that. He predicted (in the 1990s) that
the future would *not* be like Star Trek, because human reproduction
depends on genuine relationships being cheaper/easier than artificial
ones. If you could go onto the holodeck and create yourself the
perfect (wo)man of your dreams, why would you ever date a real one?
The holodeck would be humanity's last invention.

>> When's the last time you saw somebody typing commands to a computer on
>> Star Trek?
>
> 1986, when I last saw Star Trek IV.

You actually watched it? I got pretty much bored with the series
before even finishing TNG. (I'm not 100% sure, but I think I watched
every TOS episode.)

> The Star Trek universe also predicts that money will be obsolete. How's
> that prediction working out?

And it further predicts that, thanks to the invention of the holodeck
and the replicator, humanity will lose all sense of purpose and
challenge, and will send ships out to go^H^Hgo to places where
nobody's yet been, because the entire human race is *bored out of its
petty little brain* with nothing exciting left to do. Yup, that's the
whole unpublished backstory right there, sorry for the spoilers! (I
got this from Scott Adams too. He seems to know his stuff.)

ChrisA


From steve+comp.lang.python at pearwood.info  Tue Mar 25 11:18:56 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 15:18:56 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
Message-ID: <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 05:09:20 -0700, Rustom Mody wrote:

> Two completely separate questions
> 
> 1. Symbols outside of US-104-keyboard/ASCII used for python
>    functions/constants
> 2. Non-linear math notation
> 
> It goes back not just to the first programming languages but to Turing's
> paper that what a mathematician can do on 2-d paper can be done on a 1-d
> 'tape'. IOW conflating 1 and 2 is not even a poor strawman argument --
> Its only 1 that anyone is talking about.

Not so. Mark Harris said:

    [quote]
    But what if python had a math symbols extension so that universal
    mathematics could be written the way we do it on a black|board, 
    er, I mean white|board?

I think that's pretty explicit that he's talking about writing 
mathematical code the way mathematicians write mathematics.

Antoon Pardon referred to borrowing the symbols used in mathematics. But 
the point is that the symbols come with notation: - (minus) can be prefix 
unary operator or a infix binary operator. ? (summation) is a quaternary 
operator, it takes four arguments: a variable name, a lower limit, an 
upper limit, and an expression. To be true to the mathematical notation, 
we ought to write it the way mathematicians do.

The thing is, we can't just create a ? function, because it doesn't work 
the way the summation operator works. The problem is that we would want 
syntactic support, so we could write something like this:

    p = 2
    ?(n, 1, 10, n**p)

This cannot be an ordinary function, because if it were, the n**p 
expression would be evaluated before passing the result to the function. 
We want it to delay evaluation, like a list comp:

    [n**p for n in range(1, 11)]


the expression n**p gets evaluated inside the list comp. That cannot be 
written as a function either:

    list_comp(n**p, n, range(1, 11))


Mark's idea of a maths blackboard is not ridiculous. That's what 
Mathematica does. To enter a sum like the above in Mathematica, you can 
enter:

    ESC sum ESC Ctrl+$ n=1 Ctrl+% 10 Ctrl+Space n^p


to give you the summation 

    10
    ?  n**p
    n=1


Obviously this requires a custom editor.

https://reference.wolfram.com/mathematica/tutorial/EnteringTwoDimensionalInput.html


But Mathematica is a specialist system for doing mathematics, not a 
general purpose language like Python. Of course one could *write* a 
Mathematica-like system in Python, and I expect that Sage may even have 
something like this (if it doesn't, it could) but one shouldn't hammer 
the specialised round peg of complex mathematical notation into the 
square peg of a general purpose programming language.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rustompmody at gmail.com  Tue Mar 25 11:19:43 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 25 Mar 2014 08:19:43 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <5331915b$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <lgr4hf$mbd$1@speranza.aioe.org>
 <mailman.8495.1395726527.18130.python-list@python.org>
 <lgr5pq$olp$1@speranza.aioe.org> <roy-25AA1A.08365925032014@news.panix.com>
 <2f646b95-7d73-4a60-a222-96fa3cd219df@googlegroups.com>
 <5331915b$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <c683d8ef-734e-4a44-b2af-6d642aa69033@googlegroups.com>

On Tuesday, March 25, 2014 7:53:23 PM UTC+5:30, Steven D'Aprano wrote:
> On Tue, 25 Mar 2014 05:53:45 -0700, Rustom Mody wrote:

> > And if we had hyphen '?' distinguished from minus '-' then we could have
> > lispish names like call?with?current?continuation properly spelt. And
> > then generations of programmers will thank us for increasing their
> > debugging overtime!!

> :-)

> Full Unicode support in a language is, alas, a double-edged sword. While 
> it has advantages, it also has disadvantages.

> py> ? = 1
> py> A = ? + 1
> py> assert A == ?
> Traceback (most recent call last):
> AssertionError

Even with 'good' ol ASCII giving enough trouble between O and 0, 1 and
l, we certainly dont want more such headaches!

In apps, a serious consideration of unicode entails a cycle of i18n
and l10n.  The l10n for programming languages is arguably harder -- if
python is 'localized' to some (human) language L, maybe all the
builtins should be also translated?  And whats the use of that without
full translation of the docs?  Its not a pleasing thought...

Something intermediate needs to be found...

Some thoughts (quite half cooked):
1. Human -- 'natural' -- languages and math are not in the same category
If Cyrillic A gets in Roman probably shouldn't. 

2. There needs to be some intermediate binding time -- eg when the
system is installed -- when suitable char-tables are set up.
Case-in-point: Many folks in haskell-land have wanted to replace
the '\' with the '?'. This has not worked out so far because ? belongs to the
same unicode class as other lower-case letters. So since this is possible:

Prelude> let ? = 1
Prelude> ?
1
Prelude> 

the other more-natural-to-haskell usage is precluded.
So these classes need to be changeable and late-bindable.
Not as late as runtime but later than build-time.
Probably same as the choice of locales on a system

> While I can see the appeal of certain Unicode symbols, I really wouldn't 
> like to have to deal with code that looks like this:

> x?2*y+?e**3?z?(x+1)?y?w

> If I wanted line-noise, I know where to get Perl :-)

Yes... neither Perl nor Cobol is pleasant


From steve+comp.lang.python at pearwood.info  Tue Mar 25 11:35:18 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 15:35:18 GMT
Subject: [newbie] confusion concerning fetching an element in a 2d-array
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
Message-ID: <5331a236$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 06:47:23 -0700, Jean Dubois wrote:

[...]
> Thanks for answering my question but unfortunately now I'm totally
> confused.
> Above I see parts from different programs which I can't assemble
> together to one working program (I really tried hard). Can I tell from
> your comment I shouldn't use numpy? 

No, you misunderstood me. I never suggested that you avoid numpy. If you 
read my code, I use numpy. That's the "import numpy as np", and then 
later I refer to np.

What I suggested is that you open up the Python interactive interpreter 
and use it for experimentation. Not that you avoid numpy! You will use 
numpy inside the interactive interpreter.

Do you know how to start the interactive interpreter? You seem to be 
using Linux, or maybe Mac. Open a console or xterm window, and type

python

then press Enter, and the interactive interpreter will start.


> I also don't see how to get the
> value an element specified by (row, column) from a numpy_array like
> "array_lines" in my original code

Once you build the array, you get the element the same way you tried (but 
failed) earlier:

print array_lines[1, 1]


will print the element at row 1, column 1. The problem you had before was 
that you had a one dimensional array, not a two dimensional one.


> All I need is a little python-example reading a file with e.g. three
> lines with three numbers per line and putting those numbers  as floats
> in a 3x3-numpy_array, then selecting an element from that numpy_array
> using it's row and column-number.

Yes, I'm sure you do. And you will learn much more by writing this code 
yourself.

You were very, very close with your earlier attempt. In English, you had:

* import the numpy module
* read the file into a list of text lines
* store the text lines in a numpy array
* try to print a single item from the array

but it failed because the list of lines was only one dimensional. I gave 
you some code that was very similar:

* import the numpy module
* fake a text file using a string
* split the string into a list of substrings
* convert each substring into a number (float)
* store the numbers in a numpy array
* change the size of the array to turn it from 1D to 2D
* print the array


Can you identify which part of code goes with each English description? 
That's your first job. Then identify the parts of code you want to take 
from my example and put it into your example.

Good luck, and have fun!



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From __peter__ at web.de  Tue Mar 25 12:12:12 2014
From: __peter__ at web.de (Peter Otten)
Date: Tue, 25 Mar 2014 17:12:12 +0100
Subject: [newbie] confusion concerning fetching an element in a 2d-array
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
Message-ID: <lgs9sf$h9d$1@ger.gmane.org>

Jean Dubois wrote:

> Op dinsdag 25 maart 2014 12:01:37 UTC+1 schreef Steven D'Aprano:
>> On Tue, 25 Mar 2014 03:26:26 -0700, Jean Dubois wrote:
>>
>> > I'm confused by the behaviour of the following python-script I wrote:
>> > 
>> > #!/usr/bin/env python
>> > #I first made a data file 'test.dat' with the following content
>> > #1.0 2 3
>> > #4 5 6.0
>> > #7 8 9
>> > import numpy as np
>> > lines=[line.strip() for line in open('test.dat')]
>> > #convert lines-list to numpy-array
>> > array_lines=np.array(lines)
>> > #fetch element at 2nd row, 2nd column:
>> > print array_lines[1, 1]
>> > 
>> > 
>> > When running the script I always get the following error: IndexError:
>> > invalid index
>> > 
>> > Can anyone here explain me what I am doing wrong and how to fix it?
>>
>> Yes. Inspect the array by printing it, and you'll see that it is a one-
>> dimensional array, not two, and the entries are strings:
>>
>>
>> py> import numpy as np
>> py> # simulate a text file
>> ... data = """1.0 2 3
>> ... 4 5 6.0
>> ... 7 8 9"""
>> py> lines=[line.strip() for line in data.split('\n')]
>> py> # convert lines-list to numpy-array
>> ... array_lines = np.array(lines)
>> py> print array_lines
>> ['1.0 2 3' '4 5 6.0' '7 8 9']
>>
>>
>> The interactive interpreter is your friend! You never need to guess what
>> the problem is, Python has powerful introspection abilities, one of the
>> most powerful is also one of the simplest: print. Another powerful tool
>> in the interactive interpreter is help().
>>
>> So, what to do about it? Firstly, convert your string read from a file
>> into numbers, then build your array. Here's one way:
>>
>> py> values = [float(s) for s in data.split()]
>> py> print values
>> [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]
>> py> array_lines = np.array(values)
>> py> array_lines = array_lines.reshape(3, 3)
>> py> print array_lines
>> [[ 1.  2.  3.]
>>  [ 4.  5.  6.]
>>  [ 7.  8.  9.]]
>>
> Dear Steve,
> Thanks for answering my question but unfortunately now I'm totally
> confused.
> Above I see parts from different programs which I can't
> assemble together to one working program (I really tried hard).
> Can I tell from your comment I shouldn't use numpy?
> I also don't see how to get the value an element specified by (row,
> column) from a numpy_array like "array_lines" in my original code
> 
> All I need is a little python-example reading a file with e.g. three lines
> with three numbers per line and putting those numbers  as floats in a
> 3x3-numpy_array, then selecting an element from that numpy_array using
> it's row and column-number.

I'll try, too, but be warned that I'm using the same methology as Steven. 
Try to replicate every step in the following exploration.

First let's make sure we start with the same data:

$ cat test.dat
1.0 2 3
4 5 6.0
7 8 9

Then fire up the interactve interpreter:

$ python
Python 2.7.5+ (default, Feb 27 2014, 19:37:08) 
[GCC 4.8.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy
>>> lines = [line.strip() for line in open("test.dat")]
>>> lines
['1.0 2 3', '4 5 6.0', '7 8 9']

As you can see lines is a list of three strings.
Let's break these strings into parts:

>>> cells = [line.split() for line in lines]
>>> cells
[['1.0', '2', '3'], ['4', '5', '6.0'], ['7', '8', '9']]

We now have a list of lists of strings and you can address individual items 
with

>>> cells[1][2]
'6.0'

What happens when pass this list of lists of strings to the numpy.array() 
constructor?

>>> a = numpy.array(cells)
>>> a
array([['1.0', '2', '3'],
       ['4', '5', '6.0'],
       ['7', '8', '9']], 
      dtype='|S3')
>>> a[1,2]
'6.0'

It sort of works, but the array entries are strings rather than floating 
point numbers. Let's fix that:

>>> a = numpy.array(cells, dtype=float)
>>> a
array([[ 1.,  2.,  3.],
       [ 4.,  5.,  6.],
       [ 7.,  8.,  9.]])
>>> a[1,2]
6.0

OK, now we can put the previous steps into a script:

$ cat tmp.py
import numpy
cells = [line.split() for line in open("test.dat")]
a = numpy.array(cells, dtype=float)
print a[1, 2]

Run it:
$ python tmp.py
6.0

Seems to work. But reading a 2D array from a file really looks like a common  
task -- there should be a library function for that:

$ python
Python 2.7.5+ (default, Feb 27 2014, 19:37:08) 
[GCC 4.8.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy
>>> numpy.loadtxt("test.dat")
array([[ 1.,  2.,  3.],
       [ 4.,  5.,  6.],
       [ 7.,  8.,  9.]])





From harrismh777 at gmail.com  Tue Mar 25 12:40:26 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 11:40:26 -0500
Subject: [newbie] confusion concerning fetching an element in a 2d-array
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
 <mailman.8524.1395758247.18130.python-list@python.org>
Message-ID: <5331B17A.4080009@gmail.com>

On 3/25/14 9:42 AM, Dave Angel wrote:
>> All I need is a little python-example reading a file with e.g. three lines
>> with three numbers per line and putting those numbers  as floats in a
>> 3x3-numpy_array, then selecting an element from that numpy_array using
>> it's row and column-number.
>
> If your instructor wanted you to copy examples,  he would have
>   given you one.

{ouch}


Give them a toad they'll have warts all day; teach them to eat a toad 
they'll never have warts again...   or something like that.

marcus


From harrismh777 at gmail.com  Tue Mar 25 12:58:41 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 11:58:41 -0500
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <lgr4hf$mbd$1@speranza.aioe.org>
 <mailman.8495.1395726527.18130.python-list@python.org>
 <lgr5pq$olp$1@speranza.aioe.org> <roy-25AA1A.08365925032014@news.panix.com>
Message-ID: <lgscju$41j$1@speranza.aioe.org>

On 3/25/14 7:36 AM, Roy Smith wrote:

>
>> (we're on one tiny planet, you know?)
>
> Speak for yourself.
>

Are others on this list, um, on a different planet?  Or, am I the only 
one who knows its tiny?

Yes, we're on a tiny planet revolving around a speck of a star, at the 
edge of an insignificant galaxy ...

{not that it matters}



From marcelgmr at gmail.com  Tue Mar 25 13:03:24 2014
From: marcelgmr at gmail.com (Marcel Rodrigues)
Date: Tue, 25 Mar 2014 14:03:24 -0300
Subject: How to clear all content in a Tk()
In-Reply-To: <0ed94669-6c1e-4e2f-b79d-33bed8cdde15@googlegroups.com>
References: <0ed94669-6c1e-4e2f-b79d-33bed8cdde15@googlegroups.com>
Message-ID: <CAFEv2m60zZPnCrW-9gACz2oa_v3JQ74vpoZFgYTgyO1sDi3C=w@mail.gmail.com>

What about this:

Put a Frame() inside the root: `frame = Frame(root)`. This frame will be
the only immediate child of root. Everything else will be put inside the
frame. When you need to clear the root, call `frame.destroy()`. This will
destroy `frame` and all its children. You will need to recreate the frame,
but not the root.


2014-03-24 17:30 GMT-03:00 <eneskristo at gmail.com>:

> I have this program, and since I want to change stuff dynamically, I want
> to fully clear the root = Tk(), without deleting it. Is there a way to do
> so?
> --
> https://mail.python.org/mailman/listinfo/python-list
>
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From kwpolska at gmail.com  Tue Mar 25 13:24:10 2014
From: kwpolska at gmail.com (=?UTF-8?B?Q2hyaXMg4oCcS3dwb2xza2HigJ0gV2Fycmljaw==?=)
Date: Tue, 25 Mar 2014 18:24:10 +0100
Subject: Time we switched to unicode?
In-Reply-To: <87ior2zosv.fsf@elektro.pacujo.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <87ior2zosv.fsf@elektro.pacujo.net>
Message-ID: <CAMw+j7KhFc3AVrQHJTmwBo+RcQ4CNAvTZNJY+MC2-4GLW1Awdw@mail.gmail.com>

On Tue, Mar 25, 2014 at 9:05 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> On Tue, Mar 25, 2014 at 4:14 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
>>>>>> ?? = pi
>>
>> That's good! (Although typing ?? quicker than pi is majorly pushing it.
>
> It don't think that's good. The lower-case letter ?? should be used. The
> upper-case letter is used for a product, although unicode dedicates a
> separate character for the purpose: ??.
>
> I often see Americans, especially, confuse upper and lower-case letters
> in symbols ("KM" for "km", "L" for "l" etc).


?L? is actually valid, and so is ?l?.  This happens mainly because
humans (and computers) tend to write ?1 l? (one liter, one-ell) in a
way that makes it harder to distinguish (becoming eleven or ell-ell),
especially if you don?t include the space (which is invalid).

On Tue, Mar 25, 2014 at 9:23 AM, Chris Angelico <rosuav at gmail.com> wrote:
> If you can type a capital ??, you can type a lower-case ??, unless there's something very weird going on.

Nitpick time!  (because we all love it so much!)

?? = U+03A0 GREEK CAPITAL LETTER PI
?? = U+03C0 GREEK SMALL LETTER PI
?? = U+220F N-ARY PRODUCT

?If you can type an N-ARY PRODUCT, you can type a GREEK SMALL LETTER
PI, unless there?s something very weird going on.?

?like, the user is in the past and is using ISO 8859-7 (instead of a
21st-century encoding, like UTF-8).  An encoding which has support for
?? and ??, but not for ??? (of course, this assumes that, if we add
those new characters into python, we allow any encoding, somehow.)

That?s not too weird, other than the ancient encoding being used.
(though that?s a bit less weird on Windows, but that?d be
Windows-1253.)

Oh: and speaking of fancy Unicode characters that are worthless
~duplicates, spot the difference here:

? ?

If you are lucky enough (and, luckiness may involve reading this
e-mail in Helvetica (not Neue though) on a Mac), you can clearly see
that they are different.  If you are using a font that does not
differentiate them, you may think they?re the same.  If you ask some
intelligent software (like `unicodedata.name()` in Python), you?ll
quickly find out the first is MICRO SIGN, and the other is GREEK SMALL
LETTER MU.  Such craziness is what makes Unicode Unicode.

-- 
Chris ?Kwpolska? Warrick <http://kwpolska.tk>
PGP: 5EAAEA16
stop html mail | always bottom-post | only UTF-8 makes sense


From rborole06 at gmail.com  Tue Mar 25 14:16:20 2014
From: rborole06 at gmail.com (rborole06 at gmail.com)
Date: Tue, 25 Mar 2014 11:16:20 -0700 (PDT)
Subject: python installation on windows
In-Reply-To: <op.xc7fkg2m5079vu@gnudebeest>
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
 <op.xc7fkg2m5079vu@gnudebeest>
Message-ID: <f154fd7a-30c2-4165-8c9c-6441f15a1fa4@googlegroups.com>

On Sunday, 23 March 2014 18:22:54 UTC-8, Rhodri James  wrote:
> On Sun, 23 Mar 2014 17:09:09 -0000, <rborole06 at gmail.com> wrote:
> 
> 
> 
> > Hi Everybody
> 
> >
> 
> > actually i want to run python on web browser.
> 
> 
> 
> Actually you don't.  You want to run Python on a web server, which  
> 
> fortunately is a good deal easier.
> 
> 
> 
> > I downloaded python and installed but i'm not able to run it in browser  
> 
> > but it running using command prompt. so i trying to install mod_wsgi  
> 
> > 3.4. So i downloaded precompiled version mod_wsgi-3.4.ap22.win32-py2.6  
> 
> > and copied mod_wsgi.so file to C:\wamp\bin\apache\Apache2.2.11\modules  
> 
> > after i'm trying to run .\configure on path C:\Documents and  
> 
> > Settings\Rahul\Desktop\mod_wsgi-3.4.ap22.win32-py2.6 but it giving me  
> 
> > error that .\configure is not recognized as internal or external command.
> 
> >
> 
> > So please suggest me what can i do for that, i'm so beginner to python  
> 
> > and installing and configuring modules for apache.
> 
> 
> 
> The ".\configure" thing is for Linux installations using autotools; it's  
> 
> not going to work on Windows.
> 
> 
> 
> I don't run Apache on Windows, so I'm just guessing from the documentation  
> 
> here, but the mod_wsgi "Installation on Windows" page says to "follow the  
> 
> instructions for loading mod_wsgi in the Quick Installation Guide."  The  
> 
> "Quick Installation Guide" page has instructions for editing the Apache  
> 
> config files.  No mention of running ".\configure" -- why are you doing  
> 
> that?  Try just editing the config files as the documentation suggests and  
> 
> see if that works.
> 
> 
> 
> -- 
> 
> Rhodri James *-* Wildebeest Herder to the Masses

Thanks for your comment but i also edited httpd.conf file then my wamp not running
LoadModule php5_module "c:/wamp/bin/php/php5.3.0/php5apache2_2.dll"
This line i added on line 128 but nothing. Wampserver showing yellow.
I'm not getting what happening. I'm doing as per suggested in documentation

Thanks



From rborole06 at gmail.com  Tue Mar 25 14:17:30 2014
From: rborole06 at gmail.com (rborole06 at gmail.com)
Date: Tue, 25 Mar 2014 11:17:30 -0700 (PDT)
Subject: python installation on windows
In-Reply-To: <f154fd7a-30c2-4165-8c9c-6441f15a1fa4@googlegroups.com>
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
 <op.xc7fkg2m5079vu@gnudebeest>
 <f154fd7a-30c2-4165-8c9c-6441f15a1fa4@googlegroups.com>
Message-ID: <96fa02bf-7c6d-4b12-8791-d640d5910173@googlegroups.com>

On Tuesday, 25 March 2014 10:16:20 UTC-8, rbor... at gmail.com  wrote:
> On Sunday, 23 March 2014 18:22:54 UTC-8, Rhodri James  wrote:
> 
> > On Sun, 23 Mar 2014 17:09:09 -0000, <rborole06 at gmail.com> wrote:
> 
> > 
> 
> > 
> 
> > 
> 
> > > Hi Everybody
> 
> > 
> 
> > >
> 
> > 
> 
> > > actually i want to run python on web browser.
> 
> > 
> 
> > 
> 
> > 
> 
> > Actually you don't.  You want to run Python on a web server, which  
> 
> > 
> 
> > fortunately is a good deal easier.
> 
> > 
> 
> > 
> 
> > 
> 
> > > I downloaded python and installed but i'm not able to run it in browser  
> 
> > 
> 
> > > but it running using command prompt. so i trying to install mod_wsgi  
> 
> > 
> 
> > > 3.4. So i downloaded precompiled version mod_wsgi-3.4.ap22.win32-py2.6  
> 
> > 
> 
> > > and copied mod_wsgi.so file to C:\wamp\bin\apache\Apache2.2.11\modules  
> 
> > 
> 
> > > after i'm trying to run .\configure on path C:\Documents and  
> 
> > 
> 
> > > Settings\Rahul\Desktop\mod_wsgi-3.4.ap22.win32-py2.6 but it giving me  
> 
> > 
> 
> > > error that .\configure is not recognized as internal or external command.
> 
> > 
> 
> > >
> 
> > 
> 
> > > So please suggest me what can i do for that, i'm so beginner to python  
> 
> > 
> 
> > > and installing and configuring modules for apache.
> 
> > 
> 
> > 
> 
> > 
> 
> > The ".\configure" thing is for Linux installations using autotools; it's  
> 
> > 
> 
> > not going to work on Windows.
> 
> > 
> 
> > 
> 
> > 
> 
> > I don't run Apache on Windows, so I'm just guessing from the documentation  
> 
> > 
> 
> > here, but the mod_wsgi "Installation on Windows" page says to "follow the  
> 
> > 
> 
> > instructions for loading mod_wsgi in the Quick Installation Guide."  The  
> 
> > 
> 
> > "Quick Installation Guide" page has instructions for editing the Apache  
> 
> > 
> 
> > config files.  No mention of running ".\configure" -- why are you doing  
> 
> > 
> 
> > that?  Try just editing the config files as the documentation suggests and  
> 
> > 
> 
> > see if that works.
> 
> > 
> 
> > 
> 
> > 
> 
> > -- 
> 
> > 
> 
> > Rhodri James *-* Wildebeest Herder to the Masses
> 
> 
> 
> Thanks for your comment but i also edited httpd.conf file then my wamp not running
> 
> LoadModule php5_module "c:/wamp/bin/php/php5.3.0/php5apache2_2.dll"
> 
> This line i added on line 128 but nothing. Wampserver showing yellow.
> 
> I'm not getting what happening. I'm doing as per suggested in documentation
> 
> 
> 
> Thanks

And again if i'm removing this line then wampserver works properly


From rborole06 at gmail.com  Tue Mar 25 14:18:20 2014
From: rborole06 at gmail.com (rborole06 at gmail.com)
Date: Tue, 25 Mar 2014 11:18:20 -0700 (PDT)
Subject: python installation on windows
In-Reply-To: <73a660da-9dd8-4104-ae9c-ba1788ae1d60@googlegroups.com>
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
 <c7619a46-3c79-4eb8-9383-0fb720d6c8f5@googlegroups.com>
 <73a660da-9dd8-4104-ae9c-ba1788ae1d60@googlegroups.com>
Message-ID: <9eaf90e2-55bb-4902-aac7-f515796641b9@googlegroups.com>

On Sunday, 23 March 2014 13:07:28 UTC-8, tad na  wrote:
> On Sunday, March 23, 2014 12:33:02 PM UTC-5, tad na wrote:
> 
> > On Sunday, March 23, 2014 12:09:09 PM UTC-5, rbor... at gmail.com wrote:
> 
> > > Hi Everybody
> 
> > > actually i want to run python on web browser. I downloaded python and installed but i'm not able to run it in browser but it running using command prompt. so i trying to install mod_wsgi 3.4. So i downloaded precompiled version mod_wsgi-3.4.ap22.win32-py2.6 and copied mod_wsgi.so file to C:\wamp\bin\apache\Apache2.2.11\modules after i'm trying to run .\configure on path C:\Documents and Settings\Rahul\Desktop\mod_wsgi-3.4.ap22.win32-py2.6 but it giving me error that .\configure is not recognized as internal or external command.
> 
> 
> 
> > > So please suggest me what can i do for that, i'm so beginner to python and installing and configuring modules for apache.
> 
> 
> 
> > > Thanks
> 
> 
> 
> > > Rahul
> 
> > To set up a web browser:
> 
>  
> 
> > 1.open a dos window
> 
> > 2.navigate to dir you want "served"
> 
> > 3.type "python -m SimpleHTTPServer 8888 &."
> 
> 4. open browser and type http://localhost:8888/

It's saying unable to connect to localhost


From rborole06 at gmail.com  Tue Mar 25 14:19:56 2014
From: rborole06 at gmail.com (rborole06 at gmail.com)
Date: Tue, 25 Mar 2014 11:19:56 -0700 (PDT)
Subject: python installation on windows
In-Reply-To: <mailman.8436.1395632129.18130.python-list@python.org>
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
 <c7619a46-3c79-4eb8-9383-0fb720d6c8f5@googlegroups.com>
 <73a660da-9dd8-4104-ae9c-ba1788ae1d60@googlegroups.com>
 <lgo8p6$92p$1@speranza.aioe.org>
 <mailman.8436.1395632129.18130.python-list@python.org>
Message-ID: <0de4bfdf-5c85-418b-8c9c-95b7bbe57a6f@googlegroups.com>

On Sunday, 23 March 2014 19:35:19 UTC-8, Chris Angelico  wrote:
> On Mon, Mar 24, 2014 at 2:28 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> 
> > Anyway, the PSF runs python (the interpreter) from a web server (I can
> 
> > access the python interpreter from my browser from the PSF site).
> 
> >
> 
> > How is that done simply, is possibly what the OP wants to know (me too).
> 
> 
> 
> That's a much MUCH harder thing to do than running Python code in your
> 
> web server, because of trust issues. I don't know how it's set up, but
> 
> there'll be something in there to protect the server against malicious
> 
> or accidental insanity (spinning with "while True: pass", trying to
> 
> read/write files, trying to execute commands, using up all of RAM with
> 
> "x = []\nwhile True: x.append(1)", etc, etc, etc). That's actually a
> 
> very hard problem to solve, not something where you can just say
> 
> "Here, this is how to run Python via a browser".
> 
> 
> 
> ChrisA

LoadModule wsgi_module modules/mod_wsgi.so
This line also i added but then also same problem


From harrismh777 at gmail.com  Tue Mar 25 12:40:26 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 11:40:26 -0500
Subject: [newbie] confusion concerning fetching an element in a 2d-array
In-Reply-To: <mailman.8524.1395758247.18130.python-list@python.org>
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
 <mailman.8524.1395758247.18130.python-list@python.org>
Message-ID: <5331B17A.4080009@gmail.com>

On 3/25/14 9:42 AM, Dave Angel wrote:
>> All I need is a little python-example reading a file with e.g. three lines
>> with three numbers per line and putting those numbers  as floats in a
>> 3x3-numpy_array, then selecting an element from that numpy_array using
>> it's row and column-number.
>
> If your instructor wanted you to copy examples,  he would have
>   given you one.

{ouch}


Give them a toad they'll have warts all day; teach them to eat a toad 
they'll never have warts again...   or something like that.

marcus


From harrismh777 at gmail.com  Tue Mar 25 14:30:34 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 13:30:34 -0500
Subject: unicode as valid naming symbols
Message-ID: <lgsi07$k1p$1@speranza.aioe.org>

greetings, I would like to create a lamda as follows:

? = lambda n: sqrt(n)


On my keyboard mapping the "problem" character is alt-v which produces 
the radical symbol. When trying to set the symbol as a name within the 
name-space gives a syntax error:

 >>> from math import sqrt
 >>>
 >>> ? = lambda n: sqrt(n)
SyntaxError: invalid character in identifier
 >>>
 >>>

however this works:

 >>>
 >>> ? = lambda n: sqrt(n)
 >>>
 >>> ?(2)
1.4142135623730951
 >>>

   The question is which unicode(s) are capable of being proper name 
characters, and which ones are off-limits, and why?


marcus



From jeandubois314 at gmail.com  Tue Mar 25 14:33:28 2014
From: jeandubois314 at gmail.com (Jean Dubois)
Date: Tue, 25 Mar 2014 11:33:28 -0700 (PDT)
Subject: [newbie] confusion concerning fetching an element in a 2d-array
In-Reply-To: <mailman.8526.1395763950.18130.python-list@python.org>
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
 <mailman.8526.1395763950.18130.python-list@python.org>
Message-ID: <80338ca6-b9af-4943-bf5e-318a1e2b4b15@googlegroups.com>

Op dinsdag 25 maart 2014 17:12:12 UTC+1 schreef Peter Otten:
> Jean Dubois wrote:
> > Op dinsdag 25 maart 2014 12:01:37 UTC+1 schreef Steven D'Aprano:
> >> On Tue, 25 Mar 2014 03:26:26 -0700, Jean Dubois wrote:
> >>
> >> > I'm confused by the behaviour of the following python-script I wrote:
> >> > 
> >> > #!/usr/bin/env python
> >> > #I first made a data file 'test.dat' with the following content
> >> > #1.0 2 3
> >> > #4 5 6.0
> >> > #7 8 9
> >> > import numpy as np
> >> > lines=[line.strip() for line in open('test.dat')]
> >> > #convert lines-list to numpy-array
> >> > array_lines=np.array(lines)
> >> > #fetch element at 2nd row, 2nd column:
> >> > print array_lines[1, 1]
> >> > 
> >> > 
> >> > When running the script I always get the following error: IndexError:
> >> > invalid index
> >> > 
> >> > Can anyone here explain me what I am doing wrong and how to fix it?
> >>
> >> Yes. Inspect the array by printing it, and you'll see that it is a one-
> >> dimensional array, not two, and the entries are strings:
> >>
> >>
> >> py> import numpy as np
> >> py> # simulate a text file
> >> ... data = """1.0 2 3
> >> ... 4 5 6.0
> >> ... 7 8 9"""
> >> py> lines=[line.strip() for line in data.split('\n')]
> >> py> # convert lines-list to numpy-array
> >> ... array_lines = np.array(lines)
> >> py> print array_lines
> >> ['1.0 2 3' '4 5 6.0' '7 8 9']
> >>
> >>
> >> The interactive interpreter is your friend! You never need to guess what
> >> the problem is, Python has powerful introspection abilities, one of the
> >> most powerful is also one of the simplest: print. Another powerful tool
> >> in the interactive interpreter is help().
> >>
> >> So, what to do about it? Firstly, convert your string read from a file
> >> into numbers, then build your array. Here's one way:
> >>
> >> py> values = [float(s) for s in data.split()]
> >> py> print values
> >> [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]
> >> py> array_lines = np.array(values)
> >> py> array_lines = array_lines.reshape(3, 3)
> >> py> print array_lines
> >> [[ 1.  2.  3.]
> >>  [ 4.  5.  6.]
> >>  [ 7.  8.  9.]]
> >>
> > Dear Steve,
> > Thanks for answering my question but unfortunately now I'm totally
> > confused.
> > Above I see parts from different programs which I can't
> > assemble together to one working program (I really tried hard).
> > Can I tell from your comment I shouldn't use numpy?
> > I also don't see how to get the value an element specified by (row,
> > column) from a numpy_array like "array_lines" in my original code
> > 
> > All I need is a little python-example reading a file with e.g. three lines
> > with three numbers per line and putting those numbers  as floats in a
> > 3x3-numpy_array, then selecting an element from that numpy_array using
> > it's row and column-number.
> I'll try, too, but be warned that I'm using the same methology as Steven. 
> Try to replicate every step in the following exploration.
> First let's make sure we start with the same data:
> $ cat test.dat
> 1.0 2 3
> 4 5 6.0
> 7 8 9
> Then fire up the interactve interpreter:
> $ python
> Python 2.7.5+ (default, Feb 27 2014, 19:37:08) 
> [GCC 4.8.1] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import numpy
> >>> lines = [line.strip() for line in open("test.dat")]
> >>> lines
> ['1.0 2 3', '4 5 6.0', '7 8 9']
> As you can see lines is a list of three strings.
> Let's break these strings into parts:
> >>> cells = [line.split() for line in lines]
> >>> cells
> [['1.0', '2', '3'], ['4', '5', '6.0'], ['7', '8', '9']]
> We now have a list of lists of strings and you can address individual items 
> with
> >>> cells[1][2]
> '6.0'
> What happens when pass this list of lists of strings to the numpy.array() 
> constructor?
> >>> a = numpy.array(cells)
> >>> a
> array([['1.0', '2', '3'],
>        ['4', '5', '6.0'],
>        ['7', '8', '9']], 
>       dtype='|S3')
> >>> a[1,2]
> '6.0'
> It sort of works, but the array entries are strings rather than floating 
> point numbers. Let's fix that:
> >>> a = numpy.array(cells, dtype=float)
> >>> a
> array([[ 1.,  2.,  3.],
>        [ 4.,  5.,  6.],
>        [ 7.,  8.,  9.]])
> >>> a[1,2]
> 6.0
> OK, now we can put the previous steps into a script:
> $ cat tmp.py
> import numpy
> cells = [line.split() for line in open("test.dat")]
> a = numpy.array(cells, dtype=float)
> print a[1, 2]
> Run it:
> $ python tmp.py
> 6.0
> Seems to work. But reading a 2D array from a file really looks like a common  
> task -- there should be a library function for that:
> $ python
> Python 2.7.5+ (default, Feb 27 2014, 19:37:08) 
> [GCC 4.8.1] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import numpy
> >>> numpy.loadtxt("test.dat")
> array([[ 1.,  2.,  3.],
>        [ 4.,  5.,  6.],
>        [ 7.,  8.,  9.]])

Thank you very much Peter for this great lesson, you made a lot of things
clear to me. 

sincerely
jean


From wxjmfauth at gmail.com  Tue Mar 25 14:52:40 2014
From: wxjmfauth at gmail.com (wxjmfauth at gmail.com)
Date: Tue, 25 Mar 2014 11:52:40 -0700 (PDT)
Subject: unicode as valid naming symbols
In-Reply-To: <lgsi07$k1p$1@speranza.aioe.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
Message-ID: <8c6c7b14-7f7a-4b71-987c-487e51becfed@googlegroups.com>

Le mardi 25 mars 2014 19:30:34 UTC+1, Mark H. Harris a ?crit?:
> greetings, I would like to create a lamda as follows:
> 
> 
> 
> ? = lambda n: sqrt(n)
> 
> 
> 
> 
> 
> On my keyboard mapping the "problem" character is alt-v which produces 
> 
> the radical symbol. When trying to set the symbol as a name within the 
> 
> name-space gives a syntax error:
> 
> 
> 
>  >>> from math import sqrt
> 
>  >>>
> 
>  >>> ? = lambda n: sqrt(n)
> 
> SyntaxError: invalid character in identifier
> 
>  >>>
> 
>  >>>
> 
> 
> 
> however this works:
> 
> 
> 
>  >>>
> 
>  >>> ? = lambda n: sqrt(n)
> 
>  >>>
> 
>  >>> ?(2)
> 
> 1.4142135623730951
> 
>  >>>
> 
> 
> 
>    The question is which unicode(s) are capable of being proper name 
> 
> characters, and which ones are off-limits, and why?
> 
> 
> 
> 
> 
> marcus

>>> '?'.isidentifier()
False
>>> '?'.isidentifier()
True
>>> '$'.isidentifier()
False
>>> '?'.isidentifier()
True
>>> 'a'.isidentifier()
True
>>> '?2z'.isidentifier()
True
>>> print(''.isidentifier.__doc__)
S.isidentifier() -> bool

Return True if S is a valid identifier according
to the language definition.
>>>

cf "unicode.org" doc

jmf



From jeandubois314 at gmail.com  Tue Mar 25 14:58:11 2014
From: jeandubois314 at gmail.com (Jean Dubois)
Date: Tue, 25 Mar 2014 11:58:11 -0700 (PDT)
Subject: [newbie] confusion concerning fetching an element in a 2d-array
In-Reply-To: <mailman.8524.1395758247.18130.python-list@python.org>
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
 <mailman.8524.1395758247.18130.python-list@python.org>
Message-ID: <0cf3d503-8cd6-4702-9260-b0ef3f4cf561@googlegroups.com>

Op dinsdag 25 maart 2014 15:42:13 UTC+1 schreef Dave Angel:
> Jean Dubois <jeandubois314 at gmail.com> Wrote in message:
> > Op dinsdag 25 maart 2014 12:01:37 UTC+1 schreef Steven D'Aprano:
> >>
> >> py> values = [float(s) for s in data.split()]
> >> py> print values
> >> [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]
> >> py> array_lines = np.array(values)
> >> py> array_lines = array_lines.reshape(3, 3)
> >> py> print array_lines
> >> [[ 1.  2.  3.]
> >>  [ 4.  5.  6.]
> >>  [ 7.  8.  9.]]
> >>
> > Dear Steve,
> > Thanks for answering my question but unfortunately now I'm totally
> > confused. 
> > Above I see parts from different programs which I can't
> > assemble together to one working program (I really tried hard).
> > Can I tell from your comment I shouldn't use numpy?
> > I also don't see how to get the value an element specified by (row,
> > column) from a numpy_array like "array_lines" in my original code
> I don't use numpy,  but I thought Steven's description was clear
>  enough.
> Your problem was not the extraction,  but the creation of the
>  array.  Use print to prove that to yourself. 
> > 
> > All I need is a little python-example reading a file with e.g. three lines
> > with three numbers per line and putting those numbers  as floats in a
> > 3x3-numpy_array, then selecting an element from that numpy_array using
> > it's row and column-number.
> If your instructor wanted you to copy examples,  he would have
>  given you one.
please Dave leave that belittling tone behind, there's no instructor
whatsoever involved here. I constructed this example myself as I know very
well I have to start with little pieces of code first to be able to master
larger problems later. I just wanted to figure this example out first,
and as I now learned from Peter's marvellous explanation there _is_ an
elegant solution in Python to this kind of problem.
So if you are irritated by newbie-questions in the future, just neglect
them

thanks
jean


From breamoreboy at yahoo.co.uk  Tue Mar 25 15:00:41 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 25 Mar 2014 19:00:41 +0000
Subject: python installation on windows
In-Reply-To: <96fa02bf-7c6d-4b12-8791-d640d5910173@googlegroups.com>
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
 <op.xc7fkg2m5079vu@gnudebeest>
 <f154fd7a-30c2-4165-8c9c-6441f15a1fa4@googlegroups.com>
 <96fa02bf-7c6d-4b12-8791-d640d5910173@googlegroups.com>
Message-ID: <lgsjok$nkq$1@ger.gmane.org>

On 25/03/2014 18:17, rborole06 at gmail.com wrote:

Would you please use the mailing list 
https://mail.python.org/mailman/listinfo/python-list or read and action 
this https://wiki.python.org/moin/GoogleGroupsPython to prevent us 
seeing double line spacing and single line paragraphs, thanks.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From python at mrabarnett.plus.com  Tue Mar 25 15:24:43 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 25 Mar 2014 19:24:43 +0000
Subject: unicode as valid naming symbols
In-Reply-To: <lgsi07$k1p$1@speranza.aioe.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
Message-ID: <5331D7FB.50600@mrabarnett.plus.com>

On 2014-03-25 18:30, Mark H Harris wrote:
> greetings, I would like to create a lamda as follows:
>
> ? = lambda n: sqrt(n)
>
>
> On my keyboard mapping the "problem" character is alt-v which produces
> the radical symbol. When trying to set the symbol as a name within the
> name-space gives a syntax error:
>
>   >>> from math import sqrt
>   >>>
>   >>> ? = lambda n: sqrt(n)
> SyntaxError: invalid character in identifier
>   >>>
>   >>>
>
> however this works:
>
>   >>>
>   >>> ? = lambda n: sqrt(n)
>   >>>
>   >>> ?(2)
> 1.4142135623730951
>   >>>
>
>     The question is which unicode(s) are capable of being proper name
> characters, and which ones are off-limits, and why?
>
It's explained in PEP 3131.

Basically, a name should to start with a letter (this has been extended
to include Chinese characters, etc) or an underscore.

? is a classified as Lowercase_Letter.

? is classified as Math_Symbol.


From harrismh777 at gmail.com  Tue Mar 25 15:24:11 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 14:24:11 -0500
Subject: unicode as valid naming symbols
References: <lgsi07$k1p$1@speranza.aioe.org>
 <8c6c7b14-7f7a-4b71-987c-487e51becfed@googlegroups.com>
Message-ID: <lgsl4n$s0i$1@speranza.aioe.org>

On 3/25/14 1:52 PM, wxjmfauth at gmail.com wrote:
 >>>> '?'.isidentifier()
 > False
 >>>> '?'.isidentifier()
 > True


 > S.isidentifier() -> bool
 >
 > Return True if S is a valid identifier according
 > to the language definition.
 >>>>
 >
 > cf "unicode.org" doc

Excellent, thanks!

marcus


From harrismh777 at gmail.com  Tue Mar 25 15:29:06 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 14:29:06 -0500
Subject: unicode as valid naming symbols
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
Message-ID: <5331D902.3030902@gmail.com>

On 3/25/14 2:24 PM, MRAB wrote:
 > It's explained in PEP 3131.
 >
 > Basically, a name should to start with a letter (this has been extended
 > to include Chinese characters, etc) or an underscore.
 >
 > ? is a classified as Lowercase_Letter.
 >
 > ? is classified as Math_Symbol.

    Thanks much!  I'll note that for improvements. Any unicode symbol 
(that is not a number) should be allowed as an identifier.

   marcus


From rosuav at gmail.com  Tue Mar 25 15:40:42 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 26 Mar 2014 06:40:42 +1100
Subject: Time we switched to unicode?
In-Reply-To: <CAMw+j7KhFc3AVrQHJTmwBo+RcQ4CNAvTZNJY+MC2-4GLW1Awdw@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <87ior2zosv.fsf@elektro.pacujo.net>
 <CAMw+j7KhFc3AVrQHJTmwBo+RcQ4CNAvTZNJY+MC2-4GLW1Awdw@mail.gmail.com>
Message-ID: <CAPTjJmpnFYUN9ybxE2aRQmmb4Kjz03o66M53vJsxG3dhPYrVPw@mail.gmail.com>

On Wed, Mar 26, 2014 at 4:24 AM, Chris ?Kwpolska? Warrick
<kwpolska at gmail.com> wrote:
> ?If you can type an N-ARY PRODUCT, you can type a GREEK SMALL LETTER
> PI, unless there?s something very weird going on.?
>
> ?like, the user is in the past and is using ISO 8859-7 (instead of a
> 21st-century encoding, like UTF-8).  An encoding which has support for
> ?? and ??, but not for ??? (of course, this assumes that, if we add
> those new characters into python, we allow any encoding, somehow.)
>
> That?s not too weird, other than the ancient encoding being used.

Since we opened by discussing Unicode, anyone who's cheating and using
an eight-bit character set is, well, cheating. :)

ChrisA


From davea at davea.name  Tue Mar 25 15:45:51 2014
From: davea at davea.name (Dave Angel)
Date: Tue, 25 Mar 2014 15:45:51 -0400 (EDT)
Subject: unicode as valid naming symbols
References: <lgsi07$k1p$1@speranza.aioe.org>
Message-ID: <lgsm3e$2h0$1@ger.gmane.org>

 Mark H Harris <harrismh777 at gmail.com> Wrote in message:
> greetings, I would like to create a lamda as follows:
> 
> ??? = lambda n: sqrt(n)
> 
> 
> On my keyboard mapping the "problem" character is alt-v which produces 
> the radical symbol. When trying to set the symbol as a name within the 
> name-space gives a syntax error:
> 
>  >>> from math import sqrt
>  >>>
>  >>> ??? = lambda n: sqrt(n)
> SyntaxError: invalid character in identifier
>  >>>
>  >>>
> 
> however this works:
> 
>  >>>
>  >>> ?? = lambda n: sqrt(n)
>  >>>
>  >>> ??(2)
> 1.4142135623730951
>  >>>
> 
>    The question is which unicode(s) are capable of being proper name 
> characters, and which ones are off-limits, and why?

See the official docs


 http://docs.python.org/3/reference/lexical_analysis.html#identifiers

There's also a method on str that'll tell you:  isidentifier (). 
 To see such methods,  use dir ("")

As for why, you can get a pretty good idea from the reference
 above, as it lists 12 unicode categories that can be used. You
 can also look at pep3131 and at Potsdam ' s site. Both links are
 on the above page. Letters, marks, connectors,  and numbers,  but
 not punctuation. 


-- 
DaveA



From joel.goldstick at gmail.com  Tue Mar 25 15:15:27 2014
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Tue, 25 Mar 2014 15:15:27 -0400
Subject: [newbie] confusion concerning fetching an element in a 2d-array
In-Reply-To: <0cf3d503-8cd6-4702-9260-b0ef3f4cf561@googlegroups.com>
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
 <mailman.8524.1395758247.18130.python-list@python.org>
 <0cf3d503-8cd6-4702-9260-b0ef3f4cf561@googlegroups.com>
Message-ID: <CAPM-O+x4z9cGg6EVH636kB-VnfPCd+c97FGK5+x762i+KtdArw@mail.gmail.com>

Jean, be aware there is also python tutor list you might like.  This is
sometimes a tough crowd here. Don't be discouraged. It can be a badge of
honor sometimes
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From ian.g.kelly at gmail.com  Tue Mar 25 15:49:09 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 25 Mar 2014 13:49:09 -0600
Subject: unicode as valid naming symbols
In-Reply-To: <5331D902.3030902@gmail.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
Message-ID: <CALwzidnxBqYSu_3St-zP29Fsp9s==ANoF6_VJ3fVHq7b6bU48g@mail.gmail.com>

On Tue, Mar 25, 2014 at 1:29 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/25/14 2:24 PM, MRAB wrote:
>> It's explained in PEP 3131.
>>
>> Basically, a name should to start with a letter (this has been extended
>> to include Chinese characters, etc) or an underscore.
>>
>> ? is a classified as Lowercase_Letter.
>>
>> ? is classified as Math_Symbol.
>
>    Thanks much!  I'll note that for improvements. Any unicode symbol (that
> is not a number) should be allowed as an identifier.

? cannot be used in identifiers for the same reasons that + and ~
cannot: identifiers are intended to be alphanumeric. ? is not
currently the name of an operator, but who knows what may happen in
the future?

Python generally follows Annex 31 of the Unicode standard in this regard:

http://www.unicode.org/reports/tr31/


From marko at pacujo.net  Tue Mar 25 15:48:21 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 25 Mar 2014 21:48:21 +0200
Subject: unicode as valid naming symbols
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
Message-ID: <87ha6mm54q.fsf@elektro.pacujo.net>

Mark H Harris <harrismh777 at gmail.com>:

>    Thanks much!  I'll note that for improvements. Any unicode symbol
> (that is not a number) should be allowed as an identifier.

I don't know if that's a good idea, but that's how it is in lisp/scheme.

Thus, "*" and "1+" are normal identifiers in lisp and scheme.


Marko


From davea at davea.name  Tue Mar 25 15:58:10 2014
From: davea at davea.name (Dave Angel)
Date: Tue, 25 Mar 2014 15:58:10 -0400 (EDT)
Subject: [newbie] confusion concerning fetching an element in a 2d-array
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
 <mailman.8524.1395758247.18130.python-list@python.org>
 <0cf3d503-8cd6-4702-9260-b0ef3f4cf561@googlegroups.com>
Message-ID: <lgsmqh$4tj$1@ger.gmane.org>

 Jean Dubois <jeandubois314 at gmail.com> Wrote in message:
> Op dinsdag 25 maart 2014 15:42:13 UTC+1 schreef Dave Angel:

>> If your instructor wanted you to copy examples,  he would have
>>  given you one.
> please Dave leave that belittling tone behind, there's no instructor
> whatsoever involved here. 

It wasn't my intention to belittle you; I'm sorry. But we do get a
 lot of people here asking for homework help, and not saying
 that's what it is. And when it's homework we do better explaining
 than just writing the code. 

In fact you only needed to add a line like
     data= infile.read ()
to Steven's original to get a complete working example. 

> I constructed this example myself as I know very
> well I have to start with little pieces of code first to be able to master
> larger problems later. I just wanted to figure this example out first,
> and as I now learned from Peter's marvellous explanation there _is_ an
> elegant solution in Python to this kind of problem.
> So if you are irritated by newbie-questions in the future, just neglect
> them

Not irritated,  just temporarily misguided. 


-- 
DaveA



From skip at pobox.com  Tue Mar 25 15:54:34 2014
From: skip at pobox.com (Skip Montanaro)
Date: Tue, 25 Mar 2014 14:54:34 -0500
Subject: unicode as valid naming symbols
In-Reply-To: <87ha6mm54q.fsf@elektro.pacujo.net>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <87ha6mm54q.fsf@elektro.pacujo.net>
Message-ID: <CANc-5UwOO-eK+TUO9CHUfj+Ycb1i8evEhjhwjEcZBXHdBt=bjA@mail.gmail.com>

On Tue, Mar 25, 2014 at 2:48 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> I don't know if that's a good idea, but that's how it is in lisp/scheme.
>
> Thus, "*" and "1+" are normal identifiers in lisp and scheme.

But parsing Lisp is pretty trivial.

Skip


From harrismh777 at gmail.com  Tue Mar 25 15:29:06 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Tue, 25 Mar 2014 14:29:06 -0500
Subject: unicode as valid naming symbols
In-Reply-To: <mailman.8531.1395775491.18130.python-list@python.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
Message-ID: <5331D902.3030902@gmail.com>

On 3/25/14 2:24 PM, MRAB wrote:
 > It's explained in PEP 3131.
 >
 > Basically, a name should to start with a letter (this has been extended
 > to include Chinese characters, etc) or an underscore.
 >
 > ? is a classified as Lowercase_Letter.
 >
 > ? is classified as Math_Symbol.

    Thanks much!  I'll note that for improvements. Any unicode symbol 
(that is not a number) should be allowed as an identifier.

   marcus


From greg.ewing at canterbury.ac.nz  Tue Mar 25 16:21:09 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 26 Mar 2014 09:21:09 +1300
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <roy-38C75A.08350225032014@news.panix.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <roy-38C75A.08350225032014@news.panix.com>
Message-ID: <bpe6pkF4s5lU1@mid.individual.net>

Roy Smith wrote:
> Doors that open automatically as you approach them are now 
> routine.

Star Trek doors seem to be a bit smarter, though.
Captain Kirk never had to stop in front of a door
and wait for it to sluggishly slide open. Also the
doors never open when you're just walking past and
not intending to go through.

-- 
Greg


From python.list at tim.thechases.com  Tue Mar 25 16:29:41 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Tue, 25 Mar 2014 15:29:41 -0500
Subject: unicode as valid naming symbols
In-Reply-To: <5331D902.3030902@gmail.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
Message-ID: <20140325152941.4d84c539@bigbox.christie.dr>

On 2014-03-25 14:29, Mark H Harris wrote:
>  > It's explained in PEP 3131.
>  >
>  > Basically, a name should to start with a letter (this has been
>  > extended to include Chinese characters, etc) or an underscore.
>  >
>  > ? is a classified as Lowercase_Letter.
>  >
>  > ? is classified as Math_Symbol.  
> 
>     Thanks much!  I'll note that for improvements. Any unicode
> symbol (that is not a number) should be allowed as an identifier.

It's not just about number'ness:

  >>> letter = "a"
  >>> number = "2"
  >>> letter.isidentifier()
  True
  >>> number.isidentifier()
  False
  >>> (letter + number).isidentifier()
  True

-tkc




From larry.martell at gmail.com  Tue Mar 25 16:31:10 2014
From: larry.martell at gmail.com (Larry Martell)
Date: Tue, 25 Mar 2014 16:31:10 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <bpe6pkF4s5lU1@mid.individual.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <roy-38C75A.08350225032014@news.panix.com>
 <bpe6pkF4s5lU1@mid.individual.net>
Message-ID: <CACwCsY6qAXkU2vjBhqEEqGwgnaKd6Qxb66i_iy5aOhdjdG95-A@mail.gmail.com>

On Tue, Mar 25, 2014 at 4:21 PM, Gregory Ewing
<greg.ewing at canterbury.ac.nz>wrote:

> Roy Smith wrote:
>
>> Doors that open automatically as you approach them are now routine.
>>
>
> Star Trek doors seem to be a bit smarter, though.
> Captain Kirk never had to stop in front of a door
> and wait for it to sluggishly slide open. Also the
> doors never open when you're just walking past and
> not intending to go through.


https://www.youtube.com/watch?v=JZAkGfJY05k
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From greg.ewing at canterbury.ac.nz  Tue Mar 25 16:33:40 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 26 Mar 2014 09:33:40 +1300
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <2f646b95-7d73-4a60-a222-96fa3cd219df@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <lgr4hf$mbd$1@speranza.aioe.org>
 <mailman.8495.1395726527.18130.python-list@python.org>
 <lgr5pq$olp$1@speranza.aioe.org> <roy-25AA1A.08365925032014@news.panix.com>
 <2f646b95-7d73-4a60-a222-96fa3cd219df@googlegroups.com>
Message-ID: <bpe7h2F51fdU1@mid.individual.net>

Rustom Mody wrote:
> ? for some reason seems inappropriate
> (some vague recollection that its an only English; Europeans dont use it??)

To me it's something you learn in primary school and
then grow out of when you start doing "real" mathematics.
The "/" is actually a better approximation of what
mathematicians use.

-- 
Greg


From antoine at python.org  Tue Mar 25 16:35:58 2014
From: antoine at python.org (Antoine Pitrou)
Date: Tue, 25 Mar 2014 20:35:58 +0000 (UTC)
Subject: [ANN] pathlib 1.0
Message-ID: <loom.20140325T213117-748@post.gmane.org>


Hello,

I am announcing the release of pathlib 1.0.  This version brings pathlib
up to date with the official Python 3.4 release, and also fixes a couple of 
2.7-specific issues.  Detailed changelog can be found further below.

In the future, I expect the standalone (PyPI) version of pathlib to receive
little to no updates, except if severe issues are found. New developments
and regular bug fixes will happen mostly in the Python standard library,
and be publicly available in official Python releases.

Overview
--------

pathlib offers a set of classes to handle filesystem paths.  It offers the
following advantages over using string objects:

* No more cumbersome use of os and os.path functions.  Everything can be
  done easily through operators, attribute accesses, and method calls.

* Embodies the semantics of different path types.  For example, comparing
  Windows paths ignores casing.

* Well-defined semantics, eliminating any warts or ambiguities (forward vs.
  backward slashes, etc.).

Requirements
------------

Python 3.2 or later is recommended, but pathlib is also usable with Python 2.7.

Install
-------

In Python 3.4, pathlib is now part of the standard library.  For Python 3.3
and earlier, ``easy_install pathlib`` or ``pip install pathlib`` should do
the trick.

Changelog for version 1.0
-------------------------

- Python issue #20765: Add missing documentation for PurePath.with_name()
  and PurePath.with_suffix().
- Fix test_mkdir_parents when the working directory has additional bits
  set (such as the setgid or sticky bits).
- Python issue #20111: pathlib.Path.with_suffix() now sanity checks the
  given suffix.
- Python issue #19918: Fix PurePath.relative_to() under Windows.
- Python issue #19921: When Path.mkdir() is called with parents=True, any
  missing parent is created with the default permissions, ignoring the mode
  argument (mimicking the POSIX "mkdir -p" command).
- Python issue #19887: Improve the Path.resolve() algorithm to support
  certain symlink chains.
- Make pathlib usable under Python 2.7 with unicode pathnames (only pure
  ASCII, though).
- Issue #21: fix TypeError under Python 2.7 when using new division.
- Add tox support for easier testing.


Regards

Antoine.




From greg.ewing at canterbury.ac.nz  Tue Mar 25 16:37:29 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 26 Mar 2014 09:37:29 +1300
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8516.1395751525.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
 <5331595D.5020008@rece.vub.ac.be>
 <CAPTjJmqZ32XBj7KJEeDoQLJx_57VCaaCEjSrVqAKJGHO48Crfw@mail.gmail.com>
 <53317191.7050701@rece.vub.ac.be>
 <mailman.8516.1395751525.18130.python-list@python.org>
Message-ID: <bpe7o5F51fdU2@mid.individual.net>

Chris Angelico wrote:
> But you can't do the same for braces. You'd have to eschew *both*
> literal-ish notations and use explicit constructors everywhere. Not
> clean.

This could have been dealt with by giving Python 2.7
a "from __future__ import braces_mean_sets" option or
something like that.

But I agree that the disruption would not have been
worth the benefit.

-- 
Greg


From antoine at python.org  Tue Mar 25 16:41:28 2014
From: antoine at python.org (Antoine Pitrou)
Date: Tue, 25 Mar 2014 20:41:28 +0000 (UTC)
Subject: [ANN] pathlib 1.0
References: <loom.20140325T213117-748@post.gmane.org>
Message-ID: <loom.20140325T214101-629@post.gmane.org>


Oh, and of course it is published on PyPI:
https://pypi.python.org/pypi/pathlib/

Regards

Antoine.



From greg.ewing at canterbury.ac.nz  Tue Mar 25 16:58:30 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Wed, 26 Mar 2014 09:58:30 +1300
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8525.1395758275.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <roy-38C75A.08350225032014@news.panix.com>
 <53318f0b$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8525.1395758275.18130.python-list@python.org>
Message-ID: <bpe8vkF5b4uU1@mid.individual.net>

Chris Angelico wrote:
> Hey look, we have a rogue AI... "CONSOLE!"...

Except that any rogue AI who's at all serious about
the matter would take care of that little loophole
at an early stage.

"Open the pod bay doors, HAL."

"I'm afraid I can't do that, Dave."

"CONSOLE!"

"Sorry, Dave. Nice try, but I've remapped that
command to shut down the pod's life support and
depressurise the cabin."

Fshhhhhhh....

-- 
Greg


From eneskristo at gmail.com  Tue Mar 25 17:15:11 2014
From: eneskristo at gmail.com (eneskristo at gmail.com)
Date: Tue, 25 Mar 2014 14:15:11 -0700 (PDT)
Subject: Errors on text.get()
Message-ID: <7548537d-7aee-4404-98b3-8b5ce294d971@googlegroups.com>

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Python33\lib\tkinter\__init__.py", line 1475, in __call__
    return self.func(*args)
  File "C:/Users/User/PycharmProjects/Cesarian Codes/project.py", line 43, in gen_random
    string = text.get('1.0', 'end')
  File "C:\Python33\lib\tkinter\__init__.py", line 3104, in get
    return self.tk.call(self._w, 'get', index1, index2)
_tkinter.TclError: invalid command name ".44500976.44544352"

I'm having a strange error. I haven't found anything online so far. If I should supply parts of the code, please post here. Thank you in advance!


From breamoreboy at yahoo.co.uk  Tue Mar 25 17:22:54 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 25 Mar 2014 21:22:54 +0000
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <bpe6pkF4s5lU1@mid.individual.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <roy-38C75A.08350225032014@news.panix.com> <bpe6pkF4s5lU1@mid.individual.net>
Message-ID: <lgss39$i6d$1@ger.gmane.org>

On 25/03/2014 20:21, Gregory Ewing wrote:
> Roy Smith wrote:
>> Doors that open automatically as you approach them are now routine.
>
> Star Trek doors seem to be a bit smarter, though.
> Captain Kirk never had to stop in front of a door
> and wait for it to sluggishly slide open. Also the
> doors never open when you're just walking past and
> not intending to go through.
>

Had anything gone wrong, there was always Scottie.

"What's the trouble, Scottie?".
"Main drive's gone, Captain.".
"How long will it take to fix.".
"Three days.".
"You've got 20 minutes".
"Ay ay, Captain.".

Nowadays the role of the Captain is taken by the salesman, sorry the 
Account Manager, and Scottie is played by the programming team leader.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From __peter__ at web.de  Tue Mar 25 17:39:18 2014
From: __peter__ at web.de (Peter Otten)
Date: Tue, 25 Mar 2014 22:39:18 +0100
Subject: Errors on text.get()
References: <7548537d-7aee-4404-98b3-8b5ce294d971@googlegroups.com>
Message-ID: <lgst1o$mal$1@ger.gmane.org>

eneskristo at gmail.com wrote:

> Exception in Tkinter callback
> Traceback (most recent call last):
>   File "C:\Python33\lib\tkinter\__init__.py", line 1475, in __call__
>     return self.func(*args)
>   File "C:/Users/User/PycharmProjects/Cesarian Codes/project.py", line 43,
>   in gen_random
>     string = text.get('1.0', 'end')
>   File "C:\Python33\lib\tkinter\__init__.py", line 3104, in get
>     return self.tk.call(self._w, 'get', index1, index2)
> _tkinter.TclError: invalid command name ".44500976.44544352"
> 
> I'm having a strange error. I haven't found anything online so far. If I
> should supply parts of the code, please post here. Thank you in advance!

Once you have destroyed a widget you can no longer access its data:

>>> import tkinter as tk
>>> root = tk.Tk()
>>> text = tk.Text(root)
>>> text.pack()
>>> text.get("1.0", "end")
'\n'
>>> text.destroy()
>>> text.get("1.0", "end")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.3/tkinter/__init__.py", line 3107, in get
    return self.tk.call(self._w, 'get', index1, index2)
_tkinter.TclError: invalid command name ".140692133333008"




From cs at zip.com.au  Tue Mar 25 18:16:09 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Wed, 26 Mar 2014 09:16:09 +1100
Subject: unicode as valid naming symbols
In-Reply-To: <87ha6mm54q.fsf@elektro.pacujo.net>
References: <87ha6mm54q.fsf@elektro.pacujo.net>
Message-ID: <20140325221609.GA96574@cskk.homeip.net>

On 25Mar2014 21:48, Marko Rauhamaa <marko at pacujo.net> wrote:
> Mark H Harris <harrismh777 at gmail.com>:
> >    Thanks much!  I'll note that for improvements. Any unicode symbol
> > (that is not a number) should be allowed as an identifier.
> 
> I don't know if that's a good idea, but that's how it is in lisp/scheme.

I think it is a terrible idea. Doing that preemptively prevents
allowing them for any other purpose in the future, ever.

Identifiers are easy if you stick to the corresponding Unicode class.

Sucking in every other symbol prevents other uses later. Such as using the
square root symbol as a prefix operator. Etc.

Don't be too grabby with syntax; it leaves no room  later for better syntax.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>


From tjreedy at udel.edu  Tue Mar 25 18:39:54 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 25 Mar 2014 18:39:54 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <CAPTjJmpYxoSgt78y0BzYK6kgEwcw4xSXbYhN1YfrNLVkvfoMCw@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <a434e0d3-b2e1-400d-a9a2-ac35493c2c4a@googlegroups.com>
 <mailman.8486.1395719831.18130.python-list@python.org>
 <53311887$0$2756$c3e8da3$76491128@news.astraweb.com>
 <8b4fd4f8-f626-4b0d-8bda-6b6813ca7403@googlegroups.com>
 <mailman.8500.1395729208.18130.python-list@python.org>
 <592062d8-37a1-4f80-a9db-b3b17a6215b9@googlegroups.com>
 <CAPTjJmpYxoSgt78y0BzYK6kgEwcw4xSXbYhN1YfrNLVkvfoMCw@mail.gmail.com>
Message-ID: <lgt0jn$5cq$1@ger.gmane.org>

On 3/25/2014 2:50 AM, Chris Angelico wrote:
> On Tue, Mar 25, 2014 at 5:41 PM, Rustom Mody <rustompmody at gmail.com> wrote:
>> ALl of which is isomorphic to Steven's point that forty is less
>> eyeballable than 40
>>
>> And mine that ? is more eyeballable than set([])
>
> I don't disagree that it is; the short tokens are easier to read in
> quantity. I just don't think that it's sufficient to justify piles of
> new and hard-to-look-up operators and things. (And a literal notation
> for an empty set would be a good thing. If I were designing a
> Python-like language from scratch now, I'd probably differentiate sets
> and dictionaries better, which would allow each one to have its own
> empty literal.)

If {} were empty set, {:} would be empty dict. This was considered but 
rejected for 3.0 as breaking too much code for too little benefit.


-- 
Terry Jan Reedy




From ethan at stoneleaf.us  Tue Mar 25 18:47:47 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Tue, 25 Mar 2014 15:47:47 -0700
Subject: unicode as valid naming symbols
In-Reply-To: <5331D902.3030902@gmail.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
Message-ID: <53320793.8070501@stoneleaf.us>

On 03/25/2014 12:29 PM, Mark H Harris wrote:
> On 3/25/14 2:24 PM, MRAB wrote:
>> It's explained in PEP 3131.
>>
>> Basically, a name should to start with a letter (this has been extended
>> to include Chinese characters, etc) or an underscore.
>>
>> ? is a classified as Lowercase_Letter.
>>
>> ? is classified as Math_Symbol.
>
>     Thanks much!  I'll note that for improvements. Any unicode symbol (that is not a number) should be allowed as an
> identifier.

No, it shouldn't.  Doing so would mean we could not use ? as the square root operator in the future.

Identifiers are made up of letters, numbers, and the underscore.  Considering all the unicode letters and unicode 
numbers out there, you shouldn't be lacking for names.

--
~Ethan~


From tjreedy at udel.edu  Tue Mar 25 19:55:39 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 25 Mar 2014 19:55:39 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
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 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
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Message-ID: <lgt51n$sgk$1@ger.gmane.org>

On 3/25/2014 11:18 AM, Steven D'Aprano wrote:

> The thing is, we can't just create a ? function, because it doesn't work
> the way the summation operator works. The problem is that we would want
> syntactic support, so we could write something like this:
>
>      p = 2
>      ?(n, 1, 10, n**p)

Of course we can. If we do not insist on separating the dummy name from 
the expression that contains it. this works.

def sigma(low, high, func):
     sum = 0
     for i in range(low, high+1):
         sum += func(i)
     return sum

p = 2
print(sigma(1, 10, lambda n: n**p))
 >>>
385
which looks correct. This corresponds to a notation like so

10
? n: n**p
1

which, for ranges, is more sensible that the standard. Lambda is an 
explicit rather than implicit quotation.

If you do insist on separating two things that belong together, you can 
quote with quote marks instead and join within the function to get the 
same answer.

def sig2(var, low, high, exp):
     func = eval("lambda {}: {}".format(var, exp))
     sum = 0
     for i in range(low, high+1):
         sum += func(i)
     return sum

p = 2
print(sig2('n', 1, 10, 'n**p'))
 >>>
385

To me, both these apis are 'something' like the api with implicit 
quoting, which is impossible for function calls, but common in 
statements. (This is one reason to make a construct a python statement 
rather than function. Jumping is another) Using the same api, one could 
instead expand the template to include the for loop and use exec instead 
of eval.

def sig3(var, low, high, exp):
     loca = {}
     exec(
'''\
sum = 0
for {} in range({}, {}):
     sum += {}\
'''.format(var, low, high+1, exp), globals(), loca)

     return loca['sum']

print(sig3('n', 1, 10, 'n**p'))


> This cannot be an ordinary function, because if it were, the n**p
> expression would be evaluated before passing the result to the function.

So would the dummy parameter name n.

> We want it to delay evaluation, like a list comp:
>
>      [n**p for n in range(1, 11)]
>
> the expression n**p gets evaluated inside the list comp.

Which is to say, it is implicitly quoted

> That cannot be written as a function either:
>
>      list_comp(n**p, n, range(1, 11)

It can be with explicit quoting, similar to how done for sigma.  Some 
lisps once and maybe still have 'special' functions that implicitly 
quote certain arguments. One just has to learn which functions and which 
parameters. I prefer having implicit quoting relegated to a limited set 
of statements, where is it pretty clear what must be quoted for the 
statement to make any sense. Assignment is one example, while, for, and 
comprehensions are others.

-- 
Terry Jan Reedy




From steve+comp.lang.python at pearwood.info  Tue Mar 25 19:58:17 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 25 Mar 2014 23:58:17 GMT
Subject: unicode as valid naming symbols
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
Message-ID: <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 14:29:06 -0500, Mark H Harris wrote:

> On 3/25/14 2:24 PM, MRAB wrote:
>  > It's explained in PEP 3131.
>  >
>  > Basically, a name should to start with a letter (this has been
>  > extended to include Chinese characters, etc) or an underscore.
>  >
>  > ? is a classified as Lowercase_Letter.
>  >
>  > ? is classified as Math_Symbol.
> 
>     Thanks much!  I'll note that for improvements. Any unicode symbol
> (that is not a number) should be allowed as an identifier.


To quote a great Spaniard:

    ?You keep using that word, I do not think it means what you
     think it means.?


Do you think that the ability to write this would be an improvement?

import ?
? = ?.??
? = 5*?.??
? = ? - 1
??? = [?.??**?.?*?{?|?.?} for ? in ?.?]
?.??????(???)


Of course, it's not even necessary to be that exotic. "Any unicode symbol 
that is not a number"... that means things like these:

x+y
spam.eggs
cheese["toast"]

would count as identifiers, which could lead to a little bit of parsing 
ambiguity... *wink*

There are languages that can allow arbitrary symbols as identifiers, like 
Lisp and Forth. You will note that they have a certain reputation for 
being, um, different, and although both went through periods of 
considerable popularity, both have faded in popularity since. While they 
have their strengths, and their defenders, nobody argues that they are 
readily accessible to the average programmer.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Tue Mar 25 20:12:46 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 26 Mar 2014 00:12:46 GMT
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
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 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
 <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8550.1395791763.18130.python-list@python.org>
Message-ID: <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 19:55:39 -0400, Terry Reedy wrote:

> On 3/25/2014 11:18 AM, Steven D'Aprano wrote:
> 
>> The thing is, we can't just create a ? function, because it doesn't
>> work the way the summation operator works. The problem is that we would
>> want syntactic support, so we could write something like this:
>>
>>      p = 2
>>      ?(n, 1, 10, n**p)
> 
> Of course we can. If we do not insist on separating the dummy name from
> the expression that contains it. this works.
> 
> def sigma(low, high, func):
>      sum = 0
>      for i in range(low, high+1):
>          sum += func(i)
>      return sum

There is no expression there. There is a function.

You cannot pass an expression to a function in Python, not in the sense I 
am talking about, because expressions are not first-class objects. When 
you pass:

sigma(1, 10, n**p)

the n**p gets evaluated immediately. Only with support of the compiler 
does evaluation of the expression get delayed, e.g.:

it = (n**p for n in range(1, 11))
result = (-100)**p if isinstance(p, int) else float('nan')
first = items and items[0]

If we tried to write an "and" function like this:

def and_(a, b):
    if a: return a
    return b


it wouldn't work the same as the `and` operator, because the `and` 
operator is lazy and only evaluates the right hand operator when needed, 
whereas the function call is greedy and evaluates the right hand operator 
up front, whether it is needed or not.

Passing a *function* is not the same as writing an expression. It is a 
work-around for lack of first-class expressions. Now perhaps it is an 
acceptable work-around, for some purposes at least. But if you want to 
match mathematical syntax, it's not enough.


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From tjreedy at udel.edu  Tue Mar 25 20:24:26 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 25 Mar 2014 20:24:26 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53317191.7050701@rece.vub.ac.be>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
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 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
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Message-ID: <lgt6nn$fi5$1@ger.gmane.org>

On 3/25/2014 8:07 AM, Antoon Pardon wrote:
> On 25-03-14 12:12, Chris Angelico wrote:
>
>> On Tue, Mar 25, 2014 at 9:24 PM, Antoon Pardon
>> <antoon.pardon at rece.vub.ac.be> wrote:
>>> No they didn't have to. With the transition to python3, the developers
>>> could have opted for empty braces to mean an empty set. And if they
>>> wanted a literal for an empty dictionary, they might have chosen {:}.
>>> Backward-compatibility was already broken so that wasn't an argument.
>> Python 3.0 didn't just say "to Hades with backward compatibility". The
>> breakage was only in places where it was deemed worthwhile. Changing
>> the meaning of {} would have only small benefit and would potentially
>> break a LOT of programs, so the devs were right to not do it.
>
> More programs than those who broke because print was now a function?

It is quite possible that the print change broke more than the dict 
change would have. The difference is that the print statement syntax was 
both awful and limited. The print function uses standard syntax and is 
more flexible.

The fact that print could be turned into a function shows that it did 
not need to be a statement. All other simple statements except 'pass' 
either implicitly quote an expression in the statement, jump control, or 
declare something to the compiler.

The other fact that Chris noted, that '{}' would have been valid but 
with different meanings in Py1/2 versus Py3, was a factor on the cost 
side. We generally try to avoid such ambiguities.

Except for this last point, I was in favor of the switch.

-- 
Terry Jan Reedy




From roy at panix.com  Tue Mar 25 20:58:27 2014
From: roy at panix.com (Roy Smith)
Date: Tue, 25 Mar 2014 20:58:27 -0400
Subject: YADTR (Yet Another DateTime Rant)
Message-ID: <roy-142548.20582725032014@news.panix.com>

One of my roles on this newsgroup is to periodically whine about 
stupidities in the Python datetime module.  This is one of those times.

I have some code which computes how long ago the sun set.  Being a nice 
pythonista, I'm using a timedelta to represent this value.  It would be 
difficult to imagine a less useful default way to print a timedelta:

previous sunset: -1 day, 22:25:26.295993

The idea of str() is that it's supposed to return a human-friendly 
representation of a value.  Humans do not say things like, "The sun set 
1 day ago plus 22 hours and 25 minutes".


From steve+comp.lang.python at pearwood.info  Tue Mar 25 21:01:01 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 26 Mar 2014 01:01:01 GMT
Subject: Time we switched to unicode?
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
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 <lgquvt$b7t$1@speranza.aioe.org>
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 <mailman.8490.1395724126.18130.python-list@python.org>
 <lgr3c1$k9l$1@speranza.aioe.org>
 <mailman.8491.1395725262.18130.python-list@python.org>
 <87ior2zosv.fsf@elektro.pacujo.net>
 <mailman.8528.1395768259.18130.python-list@python.org>
Message-ID: <533226cd$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 25 Mar 2014 18:24:10 +0100, Chris ?Kwpolska? Warrick wrote:

> Oh: and speaking of fancy Unicode characters that are worthless
> ~duplicates, spot the difference here:
> 
> ? ?

I take exception to your description of them as *worthless* duplicates. 
"Unfortunate" would be a better choice of word.

Unicode has (at least) two aims:

- to include every "character" used in human language (please, 
  no arguments about what defines a character); and

- to losslessly represent every character available in the
  dozens of legacy code pages and character sets.


It's that second requirement -- specifically the "lossless" part -- that 
leads to such annoyances as ? and ?.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ethan at stoneleaf.us  Tue Mar 25 21:19:30 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Tue, 25 Mar 2014 18:19:30 -0700
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <roy-142548.20582725032014@news.panix.com>
References: <roy-142548.20582725032014@news.panix.com>
Message-ID: <53322B22.6040100@stoneleaf.us>

On 03/25/2014 05:58 PM, Roy Smith wrote:
> One of my roles on this newsgroup is to periodically whine about
> stupidities in the Python datetime module.  This is one of those times.
>
> I have some code which computes how long ago the sun set.  Being a nice
> pythonista, I'm using a timedelta to represent this value.  It would be
> difficult to imagine a less useful default way to print a timedelta:
>
> previous sunset: -1 day, 22:25:26.295993
>
> The idea of str() is that it's supposed to return a human-friendly
> representation of a value.  Humans do not say things like, "The sun set
> 1 day ago plus 22 hours and 25 minutes".

I'm not sure whether to admire you for your stick-to-it-iveness, or pity you for the plight you are in.  Either the 
first or second time I hit a datetime WTF moment I wrote my own wrapper classes.

--
~Ethan~


From tjreedy at udel.edu  Tue Mar 25 22:10:23 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 25 Mar 2014 22:10:23 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53318664$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
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 <roy-333172.08211925032014@news.panix.com>
 <53318664$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgtcuc$f6v$1@ger.gmane.org>

On 3/25/2014 9:36 AM, Steven D'Aprano wrote:

> Yes, Python could have changed the meaning of {} to mean the empty set.
> But you know what? The empty set is not that important. Sets are not
> fundamental to Python. Python didn't even have sets until 2.3, and at
> first they were just a standard library module, not even built-in.

Leaving aside the fact that dicts are, conceptually, specialized sets of 
ordered pairs in which first members are both unique to equality and, in 
Python, hashable, this is all true.

> Dicts, on the other hand, are fundamental to Python.  > They are used everywhere.

I would rather say that functions/mappings are fundamental to Python, 
and in programming in general. Dicts are functions implemented as sets. 
Lists and tuples are functions implemented as tables (ordered sets). 
Callables are functions implemented as rules. The fact that functions as 
sets (dicts) are both extremely useful and not built-in to most 
languages, makes their presence in Python a major differentiating feature.

> Python is, in a very real sense, built on dicts, not sets.

It is build on functions, but dicts are a differentiating features. The 
'problem' with sets as sets is that they are purely featureless data 
structures.

 > You can implement sets starting from dicts,
 > but not the other way around:

You should be more careful about claiming impossibility;-).
Sets can be easily implemented from dicts because dicts are sets with an 
extra feature (the value associated with each key) that is easily 
ignored (or always set to the key or None). To implement a dict class 
starting with sets would be difficult because CPython sets and dicts are 
implemented in C and one cannot reach into their C internals from 
Python, or even (mostly) with the C API. One would have to implement or 
even simulate the C structures and code in Python and the result would 
be much slower.

 > dicts are more fundamental than sets.

One can easily implement floats from complex numbers by making the .imag 
part always 0. It would be much harder to implement complex numbers from 
floats, for the same reasons that it would be hard to implements dicts 
from sets. But it must be possible. Would you say that complex numbers 
are, because of this implementation quirk, more fundamental than floats?

> I'm sure it is awfully impressive that mathematicians can derive the laws
> of integer maths starting only from the empty set ?, but as far as
> programming goes that's not a very useful thing.

I agree. Deriving counts and integers from 0 and an increment function 
is much more apropos to how we use then to describe and drive algorithms 
and prove things about them.

-- 
Terry Jan Reedy




From tjreedy at udel.edu  Tue Mar 25 22:19:30 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 25 Mar 2014 22:19:30 -0400
Subject: Have you ever wondered why there are so many flavors of python.
 This post answers all your queries.
In-Reply-To: <9921c06f-c165-4e0a-8550-531aa5c01c01@googlegroups.com>
References: <9921c06f-c165-4e0a-8550-531aa5c01c01@googlegroups.com>
Message-ID: <lgtdfe$f6v$2@ger.gmane.org>

On 3/25/2014 6:52 AM, Amit Khomane wrote:
> http://www.techdarting.com/2014/03/why-different-flavors-of-python.html

This is about implementations: CPython, Jython, etc. I am not sure it 
actually answers Why?


-- 
Terry Jan Reedy



From rustompmody at gmail.com  Tue Mar 25 22:16:25 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 25 Mar 2014 19:16:25 -0700 (PDT)
Subject: unicode as valid naming symbols
In-Reply-To: <8c6c7b14-7f7a-4b71-987c-487e51becfed@googlegroups.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <8c6c7b14-7f7a-4b71-987c-487e51becfed@googlegroups.com>
Message-ID: <5b4b3af0-d9cb-4062-86c0-78fa6426d6cf@googlegroups.com>

On Wednesday, March 26, 2014 12:22:40 AM UTC+5:30, wxjm... at gmail.com wrote:
> Le mardi 25 mars 2014 19:30:34 UTC+1, Mark H. Harris a ?crit?:
> > greetings, I would like to create a lamda as follows:
> > ? = lambda n: sqrt(n)
> > On my keyboard mapping the "problem" character is alt-v which produces 
> > the radical symbol. When trying to set the symbol as a name within the 
> > name-space gives a syntax error:
> >  >>> from math import sqrt
> >  >>> ? = lambda n: sqrt(n)
> > SyntaxError: invalid character in identifier
> > however this works:
> >  >>> ? = lambda n: sqrt(n)
> >  >>> ?(2)
> > 1.4142135623730951
> >    The question is which unicode(s) are capable of being proper name 
> > characters, and which ones are off-limits, and why?
> > marcus

> >>> '?'.isidentifier()
> False
> >>> '?'.isidentifier()
> True
> >>> '$'.isidentifier()
> False
> >>> '?'.isidentifier()
> True
> >>> 'a'.isidentifier()
> True
> >>> '?2z'.isidentifier()
> True
> >>> print(''.isidentifier.__doc__)
> S.isidentifier() -> bool

> Return True if S is a valid identifier according
> to the language definition.

Thanks jmf!
You obviously have more unicode knowledge than many (most?) of us here.
And when you contribute that knowledge in short-n-sweet form as above
it is helpful to all.

> cf "unicode.org" doc

Ummm...
Less helpful here.
What/where do you expect someone to start reading?
If a python beginner asks some basic question and someone here were to say
"Go read up on http://python.org"
who is helped?


From tjreedy at udel.edu  Tue Mar 25 22:26:57 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 25 Mar 2014 22:26:57 -0400
Subject: unicode as valid naming symbols
In-Reply-To: <lgsi07$k1p$1@speranza.aioe.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
Message-ID: <lgtdtd$osr$1@ger.gmane.org>

On 3/25/2014 2:30 PM, Mark H Harris wrote:
> greetings, I would like to create a lamda as follows:

A lambda is a function lacking a proper name.

> ? = lambda n: sqrt(n)

This is discouraged in PEP8. If the following worked,

def ?(n): return sqrt(n)

would have ? as its __name__ attribute

-- 
Terry Jan Reedy




From rosuav at gmail.com  Tue Mar 25 22:39:01 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 26 Mar 2014 13:39:01 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <lgtcuc$f6v$1@ger.gmane.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
 <mailman.8511.1395743071.18130.python-list@python.org>
 <roy-333172.08211925032014@news.panix.com>
 <53318664$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgtcuc$f6v$1@ger.gmane.org>
Message-ID: <CAPTjJmrpvtr1ZND8VV_GnuaAKTNhiYEK0zaUe5vUe1rkeQi2Sw@mail.gmail.com>

On Wed, Mar 26, 2014 at 1:10 PM, Terry Reedy <tjreedy at udel.edu> wrote:
>> dicts are more fundamental than sets.
>
> One can easily implement floats from complex numbers by making the .imag
> part always 0. It would be much harder to implement complex numbers from
> floats, for the same reasons that it would be hard to implements dicts from
> sets. But it must be possible. Would you say that complex numbers are,
> because of this implementation quirk, more fundamental than floats?

I would say that this proves that dicts and complexes are more
general, rather than more fundamental. The fundamentals of boolean
logic are AND/OR/NOT, but it's common to build everything out of the
more general NAND gates because they can do everything. (I may be
sketchy on details there, I'm a software guy not a hardware designer.)

ChrisA


From python at mrabarnett.plus.com  Tue Mar 25 22:56:00 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 26 Mar 2014 02:56:00 +0000
Subject: unicode as valid naming symbols
In-Reply-To: <53320793.8070501@stoneleaf.us>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
Message-ID: <533241C0.8020109@mrabarnett.plus.com>

On 2014-03-25 22:47, Ethan Furman wrote:
> On 03/25/2014 12:29 PM, Mark H Harris wrote:
>> On 3/25/14 2:24 PM, MRAB wrote:
>>> It's explained in PEP 3131.
>>>
>>> Basically, a name should to start with a letter (this has been extended
>>> to include Chinese characters, etc) or an underscore.
>>>
>>> ? is a classified as Lowercase_Letter.
>>>
>>> ? is classified as Math_Symbol.
>>
>>     Thanks much!  I'll note that for improvements. Any unicode symbol (that is not a number) should be allowed as an
>> identifier.
>
> No, it shouldn't.  Doing so would mean we could not use ? as the square root operator in the future.
>
Or as a root operator, e.g. 3 ? x (the cube root of x).

> Identifiers are made up of letters, numbers, and the underscore.  Considering all the unicode letters and unicode
> numbers out there, you shouldn't be lacking for names.
>



From rosuav at gmail.com  Tue Mar 25 23:09:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 26 Mar 2014 14:09:43 +1100
Subject: unicode as valid naming symbols
In-Reply-To: <533241C0.8020109@mrabarnett.plus.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com>
Message-ID: <CAPTjJmosV_V0ZXf9SppYBgfHmcg-wX7yAsEprsebcF4GO+N2Vg@mail.gmail.com>

On Wed, Mar 26, 2014 at 1:56 PM, MRAB <python at mrabarnett.plus.com> wrote:
>> No, it shouldn't.  Doing so would mean we could not use ? as the square
>> root operator in the future.
>>
> Or as a root operator, e.g. 3 ? x (the cube root of x).

Or both! It could be like unary negation and binary subtraction.

ChrisA


From tjreedy at udel.edu  Wed Mar 26 00:30:21 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 26 Mar 2014 00:30:21 -0400
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
 <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8550.1395791763.18130.python-list@python.org>
 <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgtl4q$2lk$1@ger.gmane.org>

On 3/25/2014 8:12 PM, Steven D'Aprano wrote:
> On Tue, 25 Mar 2014 19:55:39 -0400, Terry Reedy wrote:
>
>> On 3/25/2014 11:18 AM, Steven D'Aprano wrote:
>>
>>> The thing is, we can't just create a ? function, because it doesn't
>>> work the way the summation operator works. The problem is that we would
>>> want syntactic support, so we could write something like this:
>>>
>>>       p = 2
>>>       ?(n, 1, 10, n**p)
>>
>> Of course we can. If we do not insist on separating the dummy name from
>> the expression that contains it. this works.
>>
>> def sigma(low, high, func):
>>       sum = 0
>>       for i in range(low, high+1):
>>           sum += func(i)
>>       return sum
>
> There is no expression there. There is a function.
>
> You cannot pass an expression to a function in Python,

One passes an unquoted expression in code by quoting it with either 
lambda, paired quote marks (Lisp used a single '), or using it in a form 
that implicitly quotes it (that includes def statements). Unquoted 
expressions in statements ultimately get passed to an internal functions.

 > not in the sense I am talking about,

well, if you eliminate all the possibilities ...

 > because expressions are not first-class objects.

The concept is not a class, and the Python stdlib does not have an 
expression class. But people have written classes to represent the 
concept. I used existing classes instead.

Expressions are not (normally) mathematical objects either.
(An exception is rewriting theory, or other theories, where strings 
representing expressions or WFFs (well-formed formulas) are the only 
objects.) Mathematicians quote expression strings by context or 
positiion. The sigma form is one of many examples.

-- 
Terry Jan Reedy




From rustompmody at gmail.com  Wed Mar 26 00:56:55 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Tue, 25 Mar 2014 21:56:55 -0700 (PDT)
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8562.1395808246.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
 <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8550.1395791763.18130.python-list@python.org>
 <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8562.1395808246.18130.python-list@python.org>
Message-ID: <7ef4355d-ef12-4931-847e-95ad8358bdc7@googlegroups.com>

On Wednesday, March 26, 2014 10:00:21 AM UTC+5:30, Terry Reedy wrote:
> On 3/25/2014 8:12 PM, Steven D'Aprano wrote:
> > On Tue, 25 Mar 2014 19:55:39 -0400, Terry Reedy wrote:
> >> On 3/25/2014 11:18 AM, Steven D'Aprano wrote:
> >>> The thing is, we can't just create a ? function, because it doesn't
> >>> work the way the summation operator works. The problem is that we would
> >>> want syntactic support, so we could write something like this:
> >>>       p = 2
> >>>       ?(n, 1, 10, n**p)
> >> Of course we can. If we do not insist on separating the dummy name from
> >> the expression that contains it. this works.
> >> def sigma(low, high, func):
> >>       sum = 0
> >>       for i in range(low, high+1):
> >>           sum += func(i)
> >>       return sum
> > There is no expression there. There is a function.
> > You cannot pass an expression to a function in Python,

> One passes an unquoted expression in code by quoting it with either 
> lambda, paired quote marks (Lisp used a single '), or using it in a form 
> that implicitly quotes it (that includes def statements). Unquoted 
> expressions in statements ultimately get passed to an internal functions.

I wrote about the two styles of quoting here:
(Yeah its under the scheme banner)
http://blog.languager.org/2013/08/applying-si-on-sicp.html

There was also a neat little tech report by David Gries from Cornell
explaining that ? ? ? ? are all 'binding-constructs' in their own sphere's
[No access to that any more though :-( ]


From patil.jay2009 at gmail.com  Wed Mar 26 01:04:26 2014
From: patil.jay2009 at gmail.com (Jaydeep Patil)
Date: Tue, 25 Mar 2014 22:04:26 -0700 (PDT)
Subject: Hold wxframe (GUI)
Message-ID: <57d2dd3d-af3b-4678-ac11-ae911bfeda60@googlegroups.com>

I constructed Two frames.
One frame consist of GUI which consist of one Ok button.

Afer click on OK button another GUI calls. But after Second gui calling, It wont stop further procesees. I need to stop futher proceeses. How can i hold second gui?


Please reply



Sample Code is:

import wx
class App(wx.App):
    '''
    classdocs
    '''
    def __init__(self,name=None):
        '''
        Constructor
        '''
        wx.App.__init__(self)
        self.d = Dashboard()
        self.d.Show()
        
    def _startMainLoop(self):
        self.MainLoop()
        pass
    
    def start(self):
        #self.d.Show()
        self._startMainLoop()
        pass


class Dashboard(wx.Frame):
    '''
    classdocs
    '''
    def __init__(self,name=None):
        '''
        Constructor
        '''
        wx.Frame.__init__(self,None,wx.ID_ANY)
        print("Frame 1")
        
        self.btnOk = wx.Button(self,-1,"OK")
        
        self.btnOk.Bind(wx.EVT_BUTTON,self.test)
    
    def test(self,event):
        print("Before")
        self.f = Dashboard1(self)  ##  I need to Stop here only
        self.f.Show()
        self.f.MakeModal(True)
        print("AFter")

        
        
class Dashboard1(wx.Frame):
    '''
    classdocs
    '''
    def __init__(self,parent):
        '''
        Constructor
        '''
        wx.Frame.__init__(self,parent,wx.ID_ANY)
        
a = App()
a.start()


Output is :
Frame 1
Before
After


From patil.jay2009 at gmail.com  Wed Mar 26 02:03:55 2014
From: patil.jay2009 at gmail.com (Jaydeep Patil)
Date: Tue, 25 Mar 2014 23:03:55 -0700 (PDT)
Subject: Hold wxframe (GUI)
In-Reply-To: <57d2dd3d-af3b-4678-ac11-ae911bfeda60@googlegroups.com>
References: <57d2dd3d-af3b-4678-ac11-ae911bfeda60@googlegroups.com>
Message-ID: <f68979f1-70bc-40e4-90ba-26f8a08f9f56@googlegroups.com>

On Wednesday, 26 March 2014 10:34:26 UTC+5:30, Jaydeep Patil  wrote:
> I constructed Two frames.
> 
> One frame consist of GUI which consist of one Ok button.
> 
> 
> 
> Afer click on OK button another GUI calls. But after Second gui calling, It wont stop further procesees. I need to stop futher proceeses. How can i hold second gui?
> 
> 
> 
> 
> 
> Please reply
> 
> 
> 
> 
> 
> 
> 
> Sample Code is:
> 
> 
> 
> import wx
> 
> class App(wx.App):
> 
>     '''
> 
>     classdocs
> 
>     '''
> 
>     def __init__(self,name=None):
> 
>         '''
> 
>         Constructor
> 
>         '''
> 
>         wx.App.__init__(self)
> 
>         self.d = Dashboard()
> 
>         self.d.Show()
> 
>         
> 
>     def _startMainLoop(self):
> 
>         self.MainLoop()
> 
>         pass
> 
>     
> 
>     def start(self):
> 
>         #self.d.Show()
> 
>         self._startMainLoop()
> 
>         pass
> 
> 
> 
> 
> 
> class Dashboard(wx.Frame):
> 
>     '''
> 
>     classdocs
> 
>     '''
> 
>     def __init__(self,name=None):
> 
>         '''
> 
>         Constructor
> 
>         '''
> 
>         wx.Frame.__init__(self,None,wx.ID_ANY)
> 
>         print("Frame 1")
> 
>         
> 
>         self.btnOk = wx.Button(self,-1,"OK")
> 
>         
> 
>         self.btnOk.Bind(wx.EVT_BUTTON,self.test)
> 
>     
> 
>     def test(self,event):
> 
>         print("Before")
> 
>         self.f = Dashboard1(self)  ##  I need to Stop here only
> 
>         self.f.Show()
> 
>         self.f.MakeModal(True)
> 
>         print("AFter")
> 
> 
> 
>         
> 
>         
> 
> class Dashboard1(wx.Frame):
> 
>     '''
> 
>     classdocs
> 
>     '''
> 
>     def __init__(self,parent):
> 
>         '''
> 
>         Constructor
> 
>         '''
> 
>         wx.Frame.__init__(self,parent,wx.ID_ANY)
> 
>         
> 
> a = App()
> 
> a.start()
> 
> 
> 
> 
> 
> Output is :
> 
> Frame 1
> 
> Before
> 
> After


Hi all, 

I need to hold the other execution part after next GUI calls?

How can do that?

Anybody can help me?


Regards
Jaydeep Patil


From wuwei23 at gmail.com  Wed Mar 26 02:35:51 2014
From: wuwei23 at gmail.com (alex23)
Date: Wed, 26 Mar 2014 16:35:51 +1000
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <lgqq99$v5j$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org>
Message-ID: <lgtsga$2ei$1@dont-email.me>

On 25/03/2014 12:39 PM, Mark H Harris wrote:
> my version semantically is "how it is perceived" by the user

Could you please stop claiming to have insight into the comprehension of 
anyone other than yourself? Hasty generalisations don't help your argument.


From dieter at handshake.de  Wed Mar 26 03:10:23 2014
From: dieter at handshake.de (dieter)
Date: Wed, 26 Mar 2014 08:10:23 +0100
Subject: gdb python how to output integer for examine memory
References: <e1e8c3a2-5d8d-4aae-9a5d-82af79be8c4c@googlegroups.com>
 <mailman.8505.1395733762.18130.python-list@python.org>
 <2aa794ce-7cc1-4d24-a30b-3fb17b89e33f@googlegroups.com>
Message-ID: <87fvm5v3j4.fsf@handshake.de>

Wesley <nispray at gmail.com> writes:
> ...
> Actually, I can now see the varialbe names at Python level and C level.
> I just want to verify x command to monitor the memory content.
> So, in my origin post, I can get variable i's address, and see the value is 1,
> then, I wanna have a try x command, the issue is, when use x/format i's address, the output is not 1, but other things:-(

All Python objects start (at C level) with a header (containing
the reference count, a pointer to the associated type and
maybe other things); the "real" value starts behind this header.

This means, to see the "1" in your example, you must skip the
associated object header -- either in the output or by adding
the size of the header to the initial address.



From patil.jay2009 at gmail.com  Wed Mar 26 04:10:09 2014
From: patil.jay2009 at gmail.com (Jaydeep Patil)
Date: Wed, 26 Mar 2014 01:10:09 -0700 (PDT)
Subject: Can we hold execution python programming till GUI event close on?
Message-ID: <0a91887c-8d23-4dce-a4dc-65793489559a@googlegroups.com>

Hi...

I have one wxframe. after click on that frame another frame opens and rest part is executed. I need ti stop the next execution after secong gui calls up.


please suggest.


From antoon.pardon at rece.vub.ac.be  Wed Mar 26 04:25:43 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 26 Mar 2014 09:25:43 +0100
Subject: unicode as valid naming symbols
In-Reply-To: <53320793.8070501@stoneleaf.us>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
Message-ID: <53328F07.20302@rece.vub.ac.be>

On 25-03-14 23:47, Ethan Furman wrote:
> On 03/25/2014 12:29 PM, Mark H Harris wrote:
>> On 3/25/14 2:24 PM, MRAB wrote:
>>> It's explained in PEP 3131.
>>>
>>> Basically, a name should to start with a letter (this has been extended
>>> to include Chinese characters, etc) or an underscore.
>>>
>>> ? is a classified as Lowercase_Letter.
>>>
>>> ? is classified as Math_Symbol.
>>
>>     Thanks much!  I'll note that for improvements. Any unicode symbol
>> (that is not a number) should be allowed as an
>> identifier.
>
> No, it shouldn't.  Doing so would mean we could not use ? as the
> square root operator in the future.

And what advantage would that bring over just using it as a function?

-- 
Antoon Pardon


From jeandubois314 at gmail.com  Wed Mar 26 04:47:25 2014
From: jeandubois314 at gmail.com (Jean Dubois)
Date: Wed, 26 Mar 2014 01:47:25 -0700 (PDT)
Subject: [newbie] confusion concerning fetching an element in a 2d-array
In-Reply-To: <mailman.8536.1395777200.18130.python-list@python.org>
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
 <mailman.8524.1395758247.18130.python-list@python.org>
 <0cf3d503-8cd6-4702-9260-b0ef3f4cf561@googlegroups.com>
 <mailman.8536.1395777200.18130.python-list@python.org>
Message-ID: <c154a7e0-9901-403c-958d-b888cd06f987@googlegroups.com>

Op dinsdag 25 maart 2014 20:58:10 UTC+1 schreef Dave Angel:
> Jean Dubois <jeandubois314 at gmail.com> Wrote in message:
> > Op dinsdag 25 maart 2014 15:42:13 UTC+1 schreef Dave Angel:
>
> >> If your instructor wanted you to copy examples,  he would have
> >>  given you one.
> > please Dave leave that belittling tone behind, there's no instructor
> > whatsoever involved here. 
>
> It wasn't my intention to belittle you; I'm sorry. But we do get a
>  lot of people here asking for homework help, and not saying
>  that's what it is. And when it's homework we do better explaining
>  than just writing the code. 
>
> In fact you only needed to add a line like
>      data= infile.read ()
> to Steven's original to get a complete working example. 
>
> > I constructed this example myself as I know very
> > well I have to start with little pieces of code first to be able to master
> > larger problems later. I just wanted to figure this example out first,
> > and as I now learned from Peter's marvellous explanation there _is_ an
> > elegant solution in Python to this kind of problem.
> > So if you are irritated by newbie-questions in the future, just neglect
> > them
>
> Not irritated,  just temporarily misguided. 
OK, no hard feelings

kind regards,
jean


From jeandubois314 at gmail.com  Wed Mar 26 04:48:32 2014
From: jeandubois314 at gmail.com (Jean Dubois)
Date: Wed, 26 Mar 2014 01:48:32 -0700 (PDT)
Subject: [newbie] confusion concerning fetching an element in a 2d-array
In-Reply-To: <mailman.8534.1395776687.18130.python-list@python.org>
References: <82a05fdc-1f5c-4c9b-9718-09930977268c@googlegroups.com>
 <53316211$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <dba12f0e-f169-430a-9785-b98841fd55d0@googlegroups.com>
 <mailman.8524.1395758247.18130.python-list@python.org>
 <0cf3d503-8cd6-4702-9260-b0ef3f4cf561@googlegroups.com>
 <mailman.8534.1395776687.18130.python-list@python.org>
Message-ID: <75d2eaac-d014-40bb-8027-918d79398e6c@googlegroups.com>

Op dinsdag 25 maart 2014 20:15:27 UTC+1 schreef Joel Goldstick:
> Jean, be aware there is also python tutor list you might like.? This is sometimes a tough crowd here. Don't be discouraged. It can be a badge of honor sometimes

thanks for the suggestions, I already subscribed to the python tutor list

kind regards,
jean


From antoon.pardon at rece.vub.ac.be  Wed Mar 26 04:52:25 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 26 Mar 2014 09:52:25 +0100
Subject: unicode as valid naming symbols
In-Reply-To: <533241C0.8020109@mrabarnett.plus.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com>
Message-ID: <53329549.1000208@rece.vub.ac.be>

On 26-03-14 03:56, MRAB wrote:
> On 2014-03-25 22:47, Ethan Furman wrote:
>> On 03/25/2014 12:29 PM, Mark H Harris wrote:
>>> On 3/25/14 2:24 PM, MRAB wrote:
>>>> It's explained in PEP 3131.
>>>>
>>>> Basically, a name should to start with a letter (this has been
>>>> extended
>>>> to include Chinese characters, etc) or an underscore.
>>>>
>>>> ? is a classified as Lowercase_Letter.
>>>>
>>>> ? is classified as Math_Symbol.
>>>
>>>     Thanks much!  I'll note that for improvements. Any unicode
>>> symbol (that is not a number) should be allowed as an
>>> identifier.
>>
>> No, it shouldn't.  Doing so would mean we could not use ? as the
>> square root operator in the future.
>>
> Or as a root operator, e.g. 3 ? x (the cube root of x).
>
Personally I would think such an operator is too limited to include in a programming language.
This kind of notation is only used with a constant to indicate what kind of root is taken and
only with positive integers. Something like the equivallent of the following I have never seen.

  t = 2.5
  x = 8.2
  y = t ? x

Of course we don't have to follow mathematical convention with python. However allowing any
unicode symbol as an identifier doesn't prohibit from using ? as an operator. We do have
"in" and "is" as operators now, even if they would otherwise be acceptable identifiers.
So I wonder, would you consider to introduce log as an operator. 2 log x seems an interesting
operation for a programmer.

-- 
Antoon Pardon



From antoon.pardon at rece.vub.ac.be  Wed Mar 26 05:22:22 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 26 Mar 2014 10:22:22 +0100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <lgt6nn$fi5$1@ger.gmane.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
 <5331595D.5020008@rece.vub.ac.be>
 <CAPTjJmqZ32XBj7KJEeDoQLJx_57VCaaCEjSrVqAKJGHO48Crfw@mail.gmail.com>
 <53317191.7050701@rece.vub.ac.be> <lgt6nn$fi5$1@ger.gmane.org>
Message-ID: <53329C4E.20107@rece.vub.ac.be>

On 26-03-14 01:24, Terry Reedy wrote:

> The other fact that Chris noted, that '{}' would have been valid but 
> with different meanings in Py1/2 versus Py3, was a factor on the cost 
> side. We generally try to avoid such ambiguities.
>
> Except for this last point, I was in favor of the switch.

In my estimation the cost would have been bearable. But I understand this
kind of things is always a judgement call and different people can legitimately
come to different conclusions.

-- 
Antoon Pardon



From breamoreboy at yahoo.co.uk  Wed Mar 26 05:27:51 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 26 Mar 2014 09:27:51 +0000
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <53322B22.6040100@stoneleaf.us>
References: <roy-142548.20582725032014@news.panix.com>
 <53322B22.6040100@stoneleaf.us>
Message-ID: <lgu6i9$j93$1@ger.gmane.org>

On 26/03/2014 01:19, Ethan Furman wrote:
> On 03/25/2014 05:58 PM, Roy Smith wrote:
>> One of my roles on this newsgroup is to periodically whine about
>> stupidities in the Python datetime module.  This is one of those times.
>>
>> I have some code which computes how long ago the sun set.  Being a nice
>> pythonista, I'm using a timedelta to represent this value.  It would be
>> difficult to imagine a less useful default way to print a timedelta:
>>
>> previous sunset: -1 day, 22:25:26.295993
>>
>> The idea of str() is that it's supposed to return a human-friendly
>> representation of a value.  Humans do not say things like, "The sun set
>> 1 day ago plus 22 hours and 25 minutes".
>
> I'm not sure whether to admire you for your stick-to-it-iveness, or pity
> you for the plight you are in.  Either the first or second time I hit a
> datetime WTF moment I wrote my own wrapper classes.
>

dateutils for me.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From breamoreboy at yahoo.co.uk  Wed Mar 26 05:43:06 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 26 Mar 2014 09:43:06 +0000
Subject: Hold wxframe (GUI)
In-Reply-To: <f68979f1-70bc-40e4-90ba-26f8a08f9f56@googlegroups.com>
References: <57d2dd3d-af3b-4678-ac11-ae911bfeda60@googlegroups.com>
 <f68979f1-70bc-40e4-90ba-26f8a08f9f56@googlegroups.com>
Message-ID: <lgu7eh$3oj$1@ger.gmane.org>

On 26/03/2014 06:03, Jaydeep Patil wrote:
>
> Hi all,
>
> I need to hold the other execution part after next GUI calls?
>
> How can do that?
>
> Anybody can help me?
>

I suggest you try a specific mailing list for wxpython, it's available 
at gmane.comp.python.wxpython amongst other places.

Also would you please use the mailing list 
https://mail.python.org/mailman/listinfo/python-list or read and action 
this https://wiki.python.org/moin/GoogleGroupsPython to prevent us 
seeing double line spacing and single line paragraphs, thanks.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From landa.martin at gmail.com  Wed Mar 26 05:40:13 2014
From: landa.martin at gmail.com (Martin Landa)
Date: Wed, 26 Mar 2014 02:40:13 -0700 (PDT)
Subject: calling Python script from another Python script (Windows, multiple
 installation problem)
Message-ID: <4b100198-73d0-4562-89cf-8af9b9b87174@googlegroups.com>

Hi all,

I am trying to fix a bug in the project which I am working for. The program starts on Windows via bat file which calls a Python script to set up the environment including GUI and allow to launch program-specific tools. Some of the tools are written in C, some in Python. These commands are run via subprocess.Popen class. The Windows installer comes with its own bundled Python which is usually different from possible system-wide Python. This is source of the problems, Python scripts run via subprocess.Popen are launched via system-wide Python version, not desired bundled Python. Except hacks like `Popen(sys.executable, ...)` I am looking for a better solution. I checked virtualenv [1] or Pylauncher [2] but without success, speaking about Python2 not Python3 which comes from version 3.3 with intergrated pylauncher...

Thanks in advance for any ideas, suggestions or pointers! Martin

[1] http://www.virtualenv.org/en/latest/
[2] https://bitbucket.org/vinay.sajip/pylauncher


From piotrhusiatynski at gmail.com  Wed Mar 26 07:35:31 2014
From: piotrhusiatynski at gmail.com (=?UTF-8?Q?Piotr_Husiaty=C5=84ski?=)
Date: Wed, 26 Mar 2014 12:35:31 +0100
Subject: Fwd: Basic asyncio usage
In-Reply-To: <CAKWvM9keKvSgz88oiCjnRRxmna1U3cco-MzGmKZoD9z2q2NH1A@mail.gmail.com>
References: <CAKWvM9keKvSgz88oiCjnRRxmna1U3cco-MzGmKZoD9z2q2NH1A@mail.gmail.com>
Message-ID: <CAKWvM9n2-KRTCuRbkDLGW+mJ9zNfXn_W8eYhXfwXz9hO0mD+9A@mail.gmail.com>

Hi,
I have posted the same question to python-tutor list *, but I'm trying
my luck here as advised.

I'm trying to get more familiar with asyncio library. Using python
3.4, I wrote simple echo server (see attachement for the code). I know
that instead of using bare bone send/recv I could use some of the
helper functions, but I want to start with the basics.

Using attached code, I can connect from multiple sources, but echo
won't work for all clients. Also, please look at the `sendall` mehtod
- I have to manually remove write callback, otherwise it will be
called all the time. Any tips on solving this problem?

* https://mail.python.org/pipermail/tutor/2014-March/100679.html
-------------- next part --------------
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From vlastimil.brom at gmail.com  Wed Mar 26 07:40:47 2014
From: vlastimil.brom at gmail.com (Vlastimil Brom)
Date: Wed, 26 Mar 2014 12:40:47 +0100
Subject: calling Python script from another Python script (Windows,
 multiple installation problem)
In-Reply-To: <4b100198-73d0-4562-89cf-8af9b9b87174@googlegroups.com>
References: <4b100198-73d0-4562-89cf-8af9b9b87174@googlegroups.com>
Message-ID: <CAHzaPEPgiYWweNbDLhfx+tv=shT5nc_oS7K-oYLjfsFrcPf28A@mail.gmail.com>

2014-03-26 10:40 GMT+01:00 Martin Landa <landa.martin at gmail.com>:
> Hi all,
>
> I am trying to fix a bug in the project which I am working for. The program starts on Windows via bat file which calls a Python script to set up the environment including GUI and allow to launch program-specific tools. Some of the tools are written in C, some in Python. These commands are run via subprocess.Popen class. The Windows installer comes with its own bundled Python which is usually different from possible system-wide Python. This is source of the problems, Python scripts run via subprocess.Popen are launched via system-wide Python version, not desired bundled Python. Except hacks like `Popen(sys.executable, ...)` I am looking for a better solution. I checked virtualenv [1] or Pylauncher [2] but without success, speaking about Python2 not Python3 which comes from version 3.3 with intergrated pylauncher...
>
> Thanks in advance for any ideas, suggestions or pointers! Martin
>
> [1] http://www.virtualenv.org/en/latest/
> [2] https://bitbucket.org/vinay.sajip/pylauncher
> --
> https://mail.python.org/mailman/listinfo/python-list


Hi,
I'm probably missing some requirement of your use case, but I guess,
it should be possible to specify the path of the desired python
interpreter along with the executed script as an argument to
Popen(...). This should make the selection of the used python
explicit.
Or are there any other disadvantages of the current approach, which
you are solving in parallel?

hth,
  vbr


From bmcollier at gmail.com  Wed Mar 26 07:43:49 2014
From: bmcollier at gmail.com (Ben Collier)
Date: Wed, 26 Mar 2014 04:43:49 -0700 (PDT)
Subject: Dynamically reference member of array
Message-ID: <d9daaeb5-04ef-43e8-b60e-3c4ba5790a9d@googlegroups.com>

Hi all,

I know that I can dynamically reference a variable with locals()["i"], for instance, but I'd like to know how to do this with a variable in an object.

If I have an object called "device", with variables called attr1, attr2 .. attr50, how could I dynamically reference these?

It's fairly academic, but I'd like to avoid code duplication.

Thanks,

Ben


From bmcollier at gmail.com  Wed Mar 26 07:44:41 2014
From: bmcollier at gmail.com (Ben Collier)
Date: Wed, 26 Mar 2014 04:44:41 -0700 (PDT)
Subject: Dynamically reference variable in object
In-Reply-To: <d9daaeb5-04ef-43e8-b60e-3c4ba5790a9d@googlegroups.com>
References: <d9daaeb5-04ef-43e8-b60e-3c4ba5790a9d@googlegroups.com>
Message-ID: <cddebac0-8d5d-406f-8712-a9ce806a748d@googlegroups.com>

Sorry, subject was wrong. Please see below:

On Wednesday, 26 March 2014 11:43:49 UTC, Ben Collier  wrote:
> Hi all,
> 
> 
> 
> I know that I can dynamically reference a variable with locals()["i"], for instance, but I'd like to know how to do this with a variable in an object.
> 
> 
> 
> If I have an object called "device", with variables called attr1, attr2 .. attr50, how could I dynamically reference these?
> 
> 
> 
> It's fairly academic, but I'd like to avoid code duplication.
> 
> 
> 
> Thanks,
> 
> 
> 
> Ben



From bmcollier at gmail.com  Wed Mar 26 07:49:56 2014
From: bmcollier at gmail.com (Ben Collier)
Date: Wed, 26 Mar 2014 04:49:56 -0700 (PDT)
Subject: FIXED: Dynamically reference variables in object
Message-ID: <e322214a-a7ce-470c-b7b8-c73160e6b5a8@googlegroups.com>

Hi all, 

I know that I can dynamically reference a variable with locals()["i"], for instance, but I'd like to know how to do this with a variable in an object. 

If I have an object called "device", with variables called attr1, attr2 .. attr50, how could I dynamically reference these? 

It's fairly academic, but I'd like to avoid code duplication. 

Thanks, 

Ben 


From antoon.pardon at rece.vub.ac.be  Wed Mar 26 07:59:30 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 26 Mar 2014 12:59:30 +0100
Subject: FIXED: Dynamically reference variables in object
In-Reply-To: <e322214a-a7ce-470c-b7b8-c73160e6b5a8@googlegroups.com>
References: <e322214a-a7ce-470c-b7b8-c73160e6b5a8@googlegroups.com>
Message-ID: <5332C122.9050902@rece.vub.ac.be>

On 26-03-14 12:49, Ben Collier wrote:
> Hi all, 
>
> I know that I can dynamically reference a variable with locals()["i"], for instance, but I'd like to know how to do this with a variable in an object. 
>
> If I have an object called "device", with variables called attr1, attr2 .. attr50, how could I dynamically reference these? 
>
> It's fairly academic, but I'd like to avoid code duplication. 
>
> Thanks, 
>
> Ben

It looks like you are asking for getattr. getattr(device, "attr1"). However unless you have
specific reasons to use atrributes (what you seem to call variables here), it seems you are
better of using a dictionary. So you could then use: device["attr1"].

-- 
Antoon Pardon



From rosuav at gmail.com  Wed Mar 26 08:04:00 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 26 Mar 2014 23:04:00 +1100
Subject: FIXED: Dynamically reference variables in object
In-Reply-To: <e322214a-a7ce-470c-b7b8-c73160e6b5a8@googlegroups.com>
References: <e322214a-a7ce-470c-b7b8-c73160e6b5a8@googlegroups.com>
Message-ID: <CAPTjJmrXFvH86RhZwrOppaRYEHw+tgsse0F5QPtJjo3WY2pJMA@mail.gmail.com>

On Wed, Mar 26, 2014 at 10:49 PM, Ben Collier <bmcollier at gmail.com> wrote:
> I know that I can dynamically reference a variable with locals()["i"], for instance, but I'd like to know how to do this with a variable in an object.
>
> If I have an object called "device", with variables called attr1, attr2 .. attr50, how could I dynamically reference these?
>
> It's fairly academic, but I'd like to avoid code duplication.
>

Check out the getattr function:

http://docs.python.org/3.5/library/functions.html#getattr

But if you're doing that sort of thing, you may want to consider using
a dictionary instead. :)

ChrisA


From landa.martin at gmail.com  Wed Mar 26 08:29:47 2014
From: landa.martin at gmail.com (Martin Landa)
Date: Wed, 26 Mar 2014 05:29:47 -0700 (PDT)
Subject: calling Python script from another Python script (Windows,
 multiple installation problem)
In-Reply-To: <mailman.8570.1395834055.18130.python-list@python.org>
References: <4b100198-73d0-4562-89cf-8af9b9b87174@googlegroups.com>
 <mailman.8570.1395834055.18130.python-list@python.org>
Message-ID: <ec0d610d-b74f-40fe-9f35-a8cfea747dc4@googlegroups.com>

Hi, 

> it should be possible to specify the path of the desired python
> 
> interpreter along with the executed script as an argument to
> 
> Popen(...). This should make the selection of the used python
> 
> explicit.
> 
> Or are there any other disadvantages of the current approach, which
> 
> you are solving in parallel?

not really, I am just searching for a better solution based on virtualenv or something similar...

Thanks, Martin


From landa.martin at gmail.com  Wed Mar 26 08:49:33 2014
From: landa.martin at gmail.com (Martin Landa)
Date: Wed, 26 Mar 2014 05:49:33 -0700 (PDT)
Subject: calling Python script from another Python script (Windows,
 multiple installation problem)
In-Reply-To: <ec0d610d-b74f-40fe-9f35-a8cfea747dc4@googlegroups.com>
References: <4b100198-73d0-4562-89cf-8af9b9b87174@googlegroups.com>
 <mailman.8570.1395834055.18130.python-list@python.org>
 <ec0d610d-b74f-40fe-9f35-a8cfea747dc4@googlegroups.com>
Message-ID: <6ba81449-5f4c-46be-ad4a-64ea8bc5b436@googlegroups.com>

Dne st?eda, 26. b?ezna 2014 13:29:47 UTC+1 Martin Landa napsal(a):

> not really, I am just searching for a better solution based on virtualenv or something similar...

particularly I am using something like

        if sys.platform == "win32":
            # get full path including file extension for scripts
            fcmd = get_real_command(args[0]) 
            if fcmd.endswith('.py'):
                args[0] = fcmd
                args.insert(0, sys.executable)

where 'args' in subprocess.Popen's argument. I just wonder if there is a better or preferable solution over this kind of a hack. Martin



From rosuav at gmail.com  Wed Mar 26 08:54:02 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 26 Mar 2014 23:54:02 +1100
Subject: calling Python script from another Python script (Windows,
 multiple installation problem)
In-Reply-To: <6ba81449-5f4c-46be-ad4a-64ea8bc5b436@googlegroups.com>
References: <4b100198-73d0-4562-89cf-8af9b9b87174@googlegroups.com>
 <mailman.8570.1395834055.18130.python-list@python.org>
 <ec0d610d-b74f-40fe-9f35-a8cfea747dc4@googlegroups.com>
 <6ba81449-5f4c-46be-ad4a-64ea8bc5b436@googlegroups.com>
Message-ID: <CAPTjJmqu4VxBXt7G0OD43dpfTiT6jinFuz4DMk49EnroV6YGRg@mail.gmail.com>

On Wed, Mar 26, 2014 at 11:49 PM, Martin Landa <landa.martin at gmail.com> wrote:
>             # get full path including file extension for scripts
>             fcmd = get_real_command(args[0])

What's that function do?

ChrisA


From landa.martin at gmail.com  Wed Mar 26 09:11:15 2014
From: landa.martin at gmail.com (Martin Landa)
Date: Wed, 26 Mar 2014 06:11:15 -0700 (PDT)
Subject: calling Python script from another Python script (Windows,
 multiple installation problem)
In-Reply-To: <mailman.8574.1395838445.18130.python-list@python.org>
References: <4b100198-73d0-4562-89cf-8af9b9b87174@googlegroups.com>
 <mailman.8570.1395834055.18130.python-list@python.org>
 <ec0d610d-b74f-40fe-9f35-a8cfea747dc4@googlegroups.com>
 <6ba81449-5f4c-46be-ad4a-64ea8bc5b436@googlegroups.com>
 <mailman.8574.1395838445.18130.python-list@python.org>
Message-ID: <5e22e138-be3b-4b91-8807-0025d5d77b92@googlegroups.com>

Dne st?eda, 26. b?ezna 2014 13:54:02 UTC+1 Chris Angelico napsal(a):
> On Wed, Mar 26, 2014 at 11:49 PM, Martin Landa <landa.martin at gmail.com> wrote:
> 
> >             # get full path including file extension for scripts
> 
> >             fcmd = get_real_command(args[0])

this function returns a full path including file extension for scripts. If 'args[0]' is a binary file in the path, it returns 'args[0]'. If 'args[0]' is detected as a script (it finds in the search path file with such name and given extension, eg. `py`) it returns full path to the file, /path/to/file/args[0].py.



From skip at pobox.com  Wed Mar 26 09:37:06 2014
From: skip at pobox.com (Skip Montanaro)
Date: Wed, 26 Mar 2014 08:37:06 -0500
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <roy-142548.20582725032014@news.panix.com>
References: <roy-142548.20582725032014@news.panix.com>
Message-ID: <CANc-5Ux71XqH-_4sM5Hy3oYEBHjW9Q6XBBKHRUJR9yJrvFk1tg@mail.gmail.com>

It's not clear to me what the correct str should be. I think the
desired format changes depending on the relative magnitude of the
timedelta object. For small values (less than a day), I agree, the
behavior is, well, odd.  You can get around that easily enough:

>>> d = datetime.timedelta(seconds=-2)
>>> str(d)
'-1 day, 23:59:58'
>>> "-%s" % -d
'-0:00:02'

The problem gets more challenging once you get into magnitudes > one
day:

>>> e = datetime.timedelta(days=-4, seconds=3605)
>>> e
datetime.timedelta(-4, 3605)
>>> print e
-4 days, 1:00:05

Hmmm... It's printing just what we said, negative four days, positive
one hour, five minutes. Let's try the trick from above:

>>> print -e
3 days, 22:59:55
>>> "-%s" % -e
'-3 days, 22:59:55'

Ehhh... not so much.  The fundamental problem here is the scope of the
minus sign. My trick assumes it applied to the entire string
representation.  It's clear that in the first case that it applies to
the entire displayed value, as there are no spaces. In the second
case, we know it only applies to the days, because it's spitting back
exactly what I fed the constructor.  So, that means the simple minus
sign trick won't work in the third case. Complicating things are that
timedelta objects are normalized internally so that the seconds field
is always non-negative (explaining the weird "-1 day, 23:59:58" string
representation of the first case).

I'm not sure there's a one-size-fits-all solution to this problem. For
offsets of less than a day, I suppose you could argue that the string
representation shouldn't include the "-1 day" bit. Beyond that, I
think you kind of have to live with what it gives you.

Skip


From d4n1h4ck at gmail.com  Wed Mar 26 09:50:52 2014
From: d4n1h4ck at gmail.com (Daniel Pimentel (d4n1))
Date: Wed, 26 Mar 2014 10:50:52 -0300
Subject: [Python-Dev] [RELEASED] Python 3.4.0
In-Reply-To: <CADbZ2qC0U6eWMGh+zBkbsKw8QeFzN756oUEg8DeZ6akvwrASGA@mail.gmail.com>
References: <53269663.9050408@hastings.org>
 <CAO41-mPV0GcV9EEPjv_DDJAOWL3O7Q6QV1ET5EN=wp-64Rwqrg@mail.gmail.com>
 <CAFYqXL-t7VurJgC8qBo0gKj0QeygNNf4NVVk2O1y3uoX7cxFbA@mail.gmail.com>
 <CADbZ2qC0U6eWMGh+zBkbsKw8QeFzN756oUEg8DeZ6akvwrASGA@mail.gmail.com>
Message-ID: <CAG4m0Sx0zuJ0Xi75mYxTB3WZs4jhnhbudX0A5q+af-JmwafULA@mail.gmail.com>

Good job men :D


2014-03-17 14:18 GMT-03:00 Alioune Dia <dia.aliounes at gmail.com>:

> yeah , asyncio is a great module, congrat for all jobs you are doing
> --Ad | Dakar
>
>
> 2014-03-17 18:11 GMT+01:00 Giampaolo Rodola' <g.rodola at gmail.com>:
>
>> The what's new looks truly amazing, with pathlib and asyncio being my
>> favourite additions.
>> Thanks for all the hard work.
>>
>>
>> On Mon, Mar 17, 2014 at 5:57 PM, Ryan Gonzalez <rymg19 at gmail.com> wrote:
>>
>>> YES!!! +1 to the authors of the statistics and pathlib modules.
>>>
>>>
>>> On Mon, Mar 17, 2014 at 1:29 AM, Larry Hastings <larry at hastings.org>wrote:
>>>
>>>>
>>>> On behalf of the Python development team, I'm thrilled to announce
>>>> the official release of Python 3.4.
>>>>
>>>>
>>>> Python 3.4 includes a range of improvements of the 3.x series, including
>>>> hundreds of small improvements and bug fixes.  Major new features and
>>>> changes in the 3.4 release series include:
>>>>
>>>> * PEP 428, a "pathlib" module providing object-oriented filesystem paths
>>>> * PEP 435, a standardized "enum" module
>>>> * PEP 436, a build enhancement that will help generate introspection
>>>>            information for builtins
>>>> * PEP 442, improved semantics for object finalization
>>>> * PEP 443, adding single-dispatch generic functions to the standard
>>>> library
>>>> * PEP 445, a new C API for implementing custom memory allocators
>>>> * PEP 446, changing file descriptors to not be inherited by default
>>>>            in subprocesses
>>>> * PEP 450, a new "statistics" module
>>>> * PEP 451, standardizing module metadata for Python's module import
>>>> system
>>>> * PEP 453, a bundled installer for the *pip* package manager
>>>> * PEP 454, a new "tracemalloc" module for tracing Python memory
>>>> allocations
>>>> * PEP 456, a new hash algorithm for Python strings and binary data
>>>> * PEP 3154, a new and improved protocol for pickled objects
>>>> * PEP 3156, a new "asyncio" module, a new framework for asynchronous I/O
>>>>
>>>>
>>>> To download Python 3.4.0 visit:
>>>>
>>>>     http://www.python.org/download/releases/3.4.0/
>>>>
>>>>
>>>> This is a production release.  Please report any issues you notice to:
>>>>
>>>>      http://bugs.python.org/
>>>>
>>>>
>>>> Enjoy!
>>>>
>>>>
>>>> --
>>>> Larry Hastings, Release Manager
>>>> larry at hastings.org
>>>> (on behalf of the entire python-dev team and 3.4's contributors)
>>>> _______________________________________________
>>>> Python-Dev mailing list
>>>> Python-Dev at python.org
>>>> https://mail.python.org/mailman/listinfo/python-dev
>>>> Unsubscribe: https://mail.python.org/mailman/options/python-dev/
>>>> rymg19%40gmail.com
>>>>
>>>
>>>
>>>
>>> --
>>> Ryan
>>> If anybody ever asks me why I prefer C++ to C, my answer will be simple:
>>> "It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't think that was
>>> nul-terminated."
>>>
>>>
>>> --
>>> https://mail.python.org/mailman/listinfo/python-list
>>>
>>>
>>
>>
>> --
>> Giampaolo - http://grodola.blogspot.com
>>
>>
>> _______________________________________________
>> Python-Dev mailing list
>> Python-Dev at python.org
>> https://mail.python.org/mailman/listinfo/python-dev
>> Unsubscribe:
>> https://mail.python.org/mailman/options/python-dev/dia.aliounes%40gmail.com
>>
>>
>
> _______________________________________________
> Python-Dev mailing list
> Python-Dev at python.org
> https://mail.python.org/mailman/listinfo/python-dev
> Unsubscribe:
> https://mail.python.org/mailman/options/python-dev/d4n1h4ck%40gmail.com
>
>


-- 
Msc. Daniel Pimentel (d4n1 <http://about.me/d4n1>)
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From antoon.pardon at rece.vub.ac.be  Wed Mar 26 10:02:15 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 26 Mar 2014 15:02:15 +0100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <roy-142548.20582725032014@news.panix.com>
References: <roy-142548.20582725032014@news.panix.com>
Message-ID: <5332DDE7.2050202@rece.vub.ac.be>

On 26-03-14 01:58, Roy Smith wrote:
> One of my roles on this newsgroup is to periodically whine about 
> stupidities in the Python datetime module.  This is one of those times.
>
> I have some code which computes how long ago the sun set.  Being a nice 
> pythonista, I'm using a timedelta to represent this value.  It would be 
> difficult to imagine a less useful default way to print a timedelta:
>
> previous sunset: -1 day, 22:25:26.295993
>
> The idea of str() is that it's supposed to return a human-friendly 
> representation of a value.  Humans do not say things like, "The sun set 
> 1 day ago plus 22 hours and 25 minutes".
There is a difference between how people say things and what is useful.
I remember when I was studying logarithms, a negative number like -5.73
was written down as ?6.27 (with a bar only over the six). That notation
had the advantage that the part after the decimal point stayed the same
if you added or subtracted whole numbers. Even if that would change the
sign.

I can't give an honest estimation of how useful this notation is because
I don't use the datetime module often enough. But I can imagine that those
who wrote the module and I expect used it often found it a useful
representation.

-- 
Antoon Pardon


From rosuav at gmail.com  Wed Mar 26 10:12:41 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 27 Mar 2014 01:12:41 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <5332DDE7.2050202@rece.vub.ac.be>
References: <roy-142548.20582725032014@news.panix.com>
 <5332DDE7.2050202@rece.vub.ac.be>
Message-ID: <CAPTjJmodr4FSDpvnYNvrFCiXG7o43rws-7661hY9KBW_sL26Kw@mail.gmail.com>

On Thu, Mar 27, 2014 at 1:02 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> There is a difference between how people say things and what is useful.
> I remember when I was studying logarithms, a negative number like -5.73
> was written down as ?6.27 (with a bar only over the six). That notation
> had the advantage that the part after the decimal point stayed the same
> if you added or subtracted whole numbers. Even if that would change the
> sign.

That's highly significant with logs, especially when you're working
with base 10 logs.

>>> math.log10(1234)
3.091315159697223
>>> math.log10(12340)
4.091315159697223
>>> math.log10(123400)
5.091315159697223
>>> math.log10(1234000)
6.091315159697223
>>> math.log10(12.34)
1.0913151596972228
>>> math.log10(1.234)
0.09131515969722287
>>> math.log10(.1234)
-0.9086848403027772
>>> math.log10(.01234)
-1.9086848403027772

By showing those last ones as 1?.091... and 2?.091..., you emphasize
the floating-point nature of the data: everything after the decimal is
the mantissa, and everything before the decimal is the exponent. I
can't say for sure as I don't really use that, but I can imagine that
there might be something similar with dates and times - it's three
days ago at 2:51, not two days and 21:09 ago.

Or maybe it's just "print it out in a way that more closely matches
the internal representation, to simplify debugging" :)

ChrisA


From eneskristo at gmail.com  Wed Mar 26 10:31:26 2014
From: eneskristo at gmail.com (eneskristo at gmail.com)
Date: Wed, 26 Mar 2014 07:31:26 -0700 (PDT)
Subject: Errors on text.get()
In-Reply-To: <7548537d-7aee-4404-98b3-8b5ce294d971@googlegroups.com>
References: <7548537d-7aee-4404-98b3-8b5ce294d971@googlegroups.com>
Message-ID: <7c3bb088-0b1d-4603-aa4c-3db680881a02@googlegroups.com>

On Tuesday, March 25, 2014 2:15:11 PM UTC-7, enesk... at gmail.com wrote:
> Exception in Tkinter callback
> 
> Traceback (most recent call last):
> 
>   File "C:\Python33\lib\tkinter\__init__.py", line 1475, in __call__
> 
>     return self.func(*args)
> 
>   File "C:/Users/User/PycharmProjects/Cesarian Codes/project.py", line 43, in gen_random
> 
>     string = text.get('1.0', 'end')
> 
>   File "C:\Python33\lib\tkinter\__init__.py", line 3104, in get
> 
>     return self.tk.call(self._w, 'get', index1, index2)
> 
> _tkinter.TclError: invalid command name ".44500976.44544352"
> 
> 
> 
> I'm having a strange error. I haven't found anything online so far. If I should supply parts of the code, please post here. Thank you in advance!

Thank you bro!


From marko at pacujo.net  Wed Mar 26 10:43:04 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 26 Mar 2014 16:43:04 +0200
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8577.1395842538.18130.python-list@python.org>
Message-ID: <87eh1pxbpj.fsf@elektro.pacujo.net>

Antoon Pardon <antoon.pardon at rece.vub.ac.be>:

> On 26-03-14 01:58, Roy Smith wrote:
>> previous sunset: -1 day, 22:25:26.295993
>>
>> The idea of str() is that it's supposed to return a human-friendly 
>> representation of a value.  Humans do not say things like, "The sun set 
>> 1 day ago plus 22 hours and 25 minutes".
> There is a difference between how people say things and what is useful.

There is a standard timedelta representation:

  <URL: http://www.schemacentral.com/sc/xsd/t-xsd_duration.html>

  <URL: http://en.wikipedia.org/wiki/ISO_8601#Durations>

If timedelta() were created today, it really should use that one because
it is the only standard one, even though few people would use that in a
human interface.

Thus:

   -P1DT22H25M26.295993S


Marko


From roy at panix.com  Wed Mar 26 11:04:53 2014
From: roy at panix.com (Roy Smith)
Date: Wed, 26 Mar 2014 08:04:53 -0700 (PDT)
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <mailman.8575.1395841035.18130.python-list@python.org>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8575.1395841035.18130.python-list@python.org>
Message-ID: <1102ec6b-6205-40f4-bb7c-d40f9d13115b@googlegroups.com>

On Wednesday, March 26, 2014 9:37:06 AM UTC-4, Skip Montanaro wrote:

> The problem gets more challenging once you get into magnitudes > one
> day:
> 
> >>> e = datetime.timedelta(days=-4, seconds=3605)
> >>> e
> datetime.timedelta(-4, 3605)
> >>> print e
> -4 days, 1:00:05
> 
> Hmmm... It's printing just what we said, negative four days, positive
> one hour, five minutes. Let's try the trick from above:

No, what you said was "negative four days, positive 3605 seconds".  Why does it make sense to normalize 3605 seconds to "1 hour, 5 seconds", but not extend that normalization to the days portion?

> Complicating things are that timedelta objects are normalized internally so that
> the seconds field is always non-negative

The whole idea of datatypes is to hide the internal representation.  If it's convenient on your platform, you can store timedeltas internally as fempto-years.  That should not affect how it prints.


From skip at pobox.com  Wed Mar 26 11:39:50 2014
From: skip at pobox.com (Skip Montanaro)
Date: Wed, 26 Mar 2014 10:39:50 -0500
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <1102ec6b-6205-40f4-bb7c-d40f9d13115b@googlegroups.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8575.1395841035.18130.python-list@python.org>
 <1102ec6b-6205-40f4-bb7c-d40f9d13115b@googlegroups.com>
Message-ID: <CANc-5Uw3VqOmKgkMYWMQR3NKY+_6v1ZG5-P9JXrVyu29jgOeBg@mail.gmail.com>

On Wed, Mar 26, 2014 at 10:04 AM, Roy Smith <roy at panix.com> wrote:
> No, what you said was "negative four days, positive 3605 seconds".

My apologies for not showing all my work, professor. I use datetime
and timedelta objects all the time. I did the arithmetic to go from
3605 to one hour, five minutes in my head.

The point of my post was that there is no obvious one best way to
present negative timedeltas in a human readable form. In my usage it's
not generally a big deal, as most of the time I want to display
datetime objects. In your case, it's obviously a problem. If Tim
thought that timedelta objects would be presented to users as a
regular course of doing business, maybe he would have given them a
strftime() method. I suggest you write a function to format it the way
you want and be done with it.

You might consider taking a crack at a strftime() (and strptime?)
implementation for timedelta objects that uses the ISO 8601 notation
and submit it as a patch for datetimemodule.c. Note though, that the
ISO8601 representation isn't without its own flaws (which might
explain why Tim avoided it BITD):

* It doesn't appear to provide a way to represent fractions of a
second (though perhaps all the fields can be fractional)
* How many days are in a month or a year? (It has format codes for
both. Writing a useful strptime is probably impossible.)
* It has other ambiguities ("M" represents both months and minutes -
what were they thinking?)

Skip


From roy at panix.com  Wed Mar 26 11:50:43 2014
From: roy at panix.com (Roy Smith)
Date: Wed, 26 Mar 2014 11:50:43 -0400
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <CANc-5Uw3VqOmKgkMYWMQR3NKY+_6v1ZG5-P9JXrVyu29jgOeBg@mail.gmail.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8575.1395841035.18130.python-list@python.org>
 <1102ec6b-6205-40f4-bb7c-d40f9d13115b@googlegroups.com>
 <CANc-5Uw3VqOmKgkMYWMQR3NKY+_6v1ZG5-P9JXrVyu29jgOeBg@mail.gmail.com>
Message-ID: <8AC2224E-B47B-45C5-998B-C4A3A624227E@panix.com>

On Mar 26, 2014, at 11:39 AM, Skip Montanaro wrote:

> The point of my post was that there is no obvious one best way to
> present negative timedeltas in a human readable form.

I agree that there are a number of possible representations which might make sense.  But, using negative days and positive hours:minutes:seconds is just bizarre.  I can't think of any possible application where that would be the desired format.


---
Roy Smith
roy at panix.com





From marko at pacujo.net  Wed Mar 26 11:58:30 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 26 Mar 2014 17:58:30 +0200
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8575.1395841035.18130.python-list@python.org>
 <1102ec6b-6205-40f4-bb7c-d40f9d13115b@googlegroups.com>
 <mailman.8581.1395848399.18130.python-list@python.org>
Message-ID: <87a9cdx87t.fsf@elektro.pacujo.net>

Skip Montanaro <skip at pobox.com>:

> Note though, that the ISO8601 representation isn't without its own
> flaws (which might explain why Tim avoided it BITD):
>
> * It doesn't appear to provide a way to represent fractions of a
> second (though perhaps all the fields can be fractional)
> * How many days are in a month or a year? (It has format codes for
> both. Writing a useful strptime is probably impossible.)
> * It has other ambiguities ("M" represents both months and minutes -
> what were they thinking?)


I don't have the (nonfree) ISO 8601 at hand, but

   <URL: http://www.schemacentral.com/sc/xsd/t-xsd_duration.html>

contains the practical answers -- xsd is one important use case for
str(timedelta), after all.

Fractions of seconds are supported -- the other fields can't be
fractional. The letter "T" separates months and minutes so there's no
ambiguity there.

str(timedelta()), unfortunately probably can't use anything but seconds
since PT1M can be 61 seconds and P1D can be 23 or 25 hours (DST). As you
say, P1M really means one month and P1Y means one year. The ambiguity is
intentional; if you mean to pay your employees monthly, the interval is
one month.


Marko


From steve+comp.lang.python at pearwood.info  Wed Mar 26 12:05:53 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 26 Mar 2014 16:05:53 GMT
Subject: Delayed evaluation of expressions [was Re: Time we switched to
 unicode?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
 <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8550.1395791763.18130.python-list@python.org>
 <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8562.1395808246.18130.python-list@python.org>
Message-ID: <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Wed, 26 Mar 2014 00:30:21 -0400, Terry Reedy wrote:

> On 3/25/2014 8:12 PM, Steven D'Aprano wrote:
>> On Tue, 25 Mar 2014 19:55:39 -0400, Terry Reedy wrote:
>>
>>> On 3/25/2014 11:18 AM, Steven D'Aprano wrote:
>>>
>>>> The thing is, we can't just create a ? function, because it doesn't
>>>> work the way the summation operator works. The problem is that we
>>>> would want syntactic support, so we could write something like this:
>>>>
>>>>       p = 2
>>>>       ?(n, 1, 10, n**p)
>>>
>>> Of course we can. If we do not insist on separating the dummy name
>>> from the expression that contains it. this works.
>>>
>>> def sigma(low, high, func):
>>>       sum = 0
>>>       for i in range(low, high+1):
>>>           sum += func(i)
>>>       return sum
>>
>> There is no expression there. There is a function.
>>
>> You cannot pass an expression to a function in Python,
> 
> One passes an unquoted expression in code by quoting it with either
> lambda, paired quote marks (Lisp used a single '), 

Passing *strings* and *functions* is not the same as having compiler 
support for delayed evaluation. At best its a second-class work-around. 
Contrast:

    def if_else(true_function, condition, false_function):
        if condition:
            return true_function()
        else:
            return false_function()

    if_else(lambda: x/0, x != 0, lambda: float("inf"))

with this:

    x/0 if x != 0 else float("inf")


Aside from the difference between the function form and operator form, 
the second case is much more direct and natural than the first.


> or using it in a form
> that implicitly quotes it (that includes def statements). Unquoted
> expressions in statements ultimately get passed to an internal
> functions.

I think you are mistaken. Take the unquoted expression `x+1`. It doesn't 
get passed to anything, it gets compiled into byte code and evaluated:

py> from dis import dis
py> dis("x+1")
  1           0 LOAD_NAME                0 (x)
              3 LOAD_CONST               0 (1)
              6 BINARY_ADD
              7 RETURN_VALUE


Perhaps you are thinking of one or two special cases, such as list comps:

py> dis("[x+1 for x in spam]")
  1           0 LOAD_CONST               0 (<code object <listcomp> at
                                            0xb7af22a0, file "<dis>",
                                            line 1>)
              3 LOAD_CONST               1 ('<listcomp>')
              6 MAKE_FUNCTION            0
              9 LOAD_NAME                0 (spam)
             12 GET_ITER
             13 CALL_FUNCTION            1 (1 positional, 0 keyword pair)
             16 RETURN_VALUE


But that's an implementation detail, not a language requirement, and it 
doesn't apply to all delayed expressions:

py> dis("1/x if x else y")
  1           0 LOAD_NAME                0 (x)
              3 POP_JUMP_IF_FALSE       14
              6 LOAD_CONST               0 (1)
              9 LOAD_NAME                0 (x)
             12 BINARY_TRUE_DIVIDE
             13 RETURN_VALUE
        >>   14 LOAD_NAME                1 (y)
             17 RETURN_VALUE


Some Python implementations may use internal functions under the hood to 
delay the evaluation of an expression, but you still need support from 
the interpreter to compile the expression as an internal function rather 
than evaluating it.


>  > not in the sense I am talking about,
> 
> well, if you eliminate all the possibilities ...

Obviously you can pass an expression to a function in the trivial sense 
that you can put an expression inside a function call. But that is not 
what I am talking about, since the expression is evaluated first, then 
the function is called:

py> dis("function(spam + eggs*cheese)")
  1           0 LOAD_NAME                0 (function)
              3 LOAD_NAME                1 (spam)
              6 LOAD_NAME                2 (eggs)
              9 LOAD_NAME                3 (cheese)
             12 BINARY_MULTIPLY
             13 BINARY_ADD
             14 CALL_FUNCTION            1 (1 positional, 0 keyword pair)
             17 RETURN_VALUE


I'm referring to delaying execution of the expression until later.

Coincidentally, the Sum function we were discussing is a notable example 
of Jensen's Device:

https://en.wikipedia.org/wiki/Jensen%27s_device

which is effectively what I'm referring to.


>  > because expressions are not first-class objects.
> 
> The concept is not a class, and the Python stdlib does not have an
> expression class. But people have written classes to represent the
> concept. I used existing classes instead.
> 
> Expressions are not (normally) mathematical objects either. (An
> exception is rewriting theory, or other theories, where strings
> representing expressions or WFFs (well-formed formulas) are the only
> objects.) Mathematicians quote expression strings by context or
> positiion. The sigma form is one of many examples.

Hmmm. I think you are misunderstanding me, possibly because I wrote 
"first-class object" when I should have called it a "first-class value". 
Sorry.

I'm not necessarily referring to creating something like an "arithmetic 
expression class" with methods and attributes. For example, sympy has 
things like that, so you can perform symbolic operations on the 
expression. That's not what I mean. 

What I mean is that you, the programmer, writes down an ordinary Python 
expression, using ordinary expression syntax, and the compiler treats it 
as a value in and of itself, rather than evaluating it to find out what 
value it has. In Python this will probably be some sort of object, but 
that's not the important part. The important part is that it is a *value*.

(Compare to languages where functions are not first-class values. You 
cannot pass a function to another function, or stick them in a list, or 
create them on the fly. You can only call them, evaluating them 
immediately.)

In Algol60, the compiler used thunks, which are a type of closure; in 
CPython, list comps use a hidden function object; the ternary if compiles 
byte code for a test and jump.

In case you haven't read the article on Jensen's Device above, in Algol60 
you can write a Sum function that behaves as a mathematician would 
expect. For example, to sum the entries of an array V for indexes 1 
through 100, a mathematician might write it something like this:

    10
    ? V[i]
    i=1

which we can rearrange to function-call syntax like this:

    Sum(i, 1, 100, V[i])


In Algol60, this function call would:

- pass the name "i" (not a string!) as the first argument;
- pass 1 as the second argument;
- pass 100 as the third argument;
- pass the expression "V[i]" (not a string!) as the fourth argument

and then *inside* the function Sum the expressions "i" and "V[i]" can be 
evaluated or assigned to as needed. Using Python syntax rather than Algol 
syntax:

def Sum(name, lower, upper, expression):
    total = 0
    for name in range(lower, upper+1):
        total += expression
    return total


This doesn't work in Python! Python lacks call-by-name semantics, so the 
function call would:

- evaluate the expression i, and pass that value as the first argument;
- pass 1 as the second argument;
- pass 100 as the third argument;
- evaluate V[i] and pass that value as the fourth argument


and then inside the function Sum "name" refers to the local variable 
name, not the caller's variable i. Likewise "expression" refers to a 
local variable, and not the caller's expression V[i].

Python has no general way of doing this. There are a few ad-hoc special 
cases, like list comps, the ternary if operator, etc. which are hard-
coded in the compiler to delay execution of expressions. For the rest, 
you have a choice:

- give up on delayed evaluation, and redesign your API; or

- manually manage the delayed evaluation yourself, using
  some combination of functions, eval or exec.


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From skip at pobox.com  Wed Mar 26 12:34:37 2014
From: skip at pobox.com (Skip Montanaro)
Date: Wed, 26 Mar 2014 11:34:37 -0500
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <87a9cdx87t.fsf@elektro.pacujo.net>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8575.1395841035.18130.python-list@python.org>
 <1102ec6b-6205-40f4-bb7c-d40f9d13115b@googlegroups.com>
 <mailman.8581.1395848399.18130.python-list@python.org>
 <87a9cdx87t.fsf@elektro.pacujo.net>
Message-ID: <CANc-5Uxd+kSr_LmBL3J3m8JVRHHVZHd80YP-EJe16fPwGfXQbQ@mail.gmail.com>

On Wed, Mar 26, 2014 at 10:58 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Fractions of seconds are supported -- the other fields can't be
> fractional.

Actually, it appears that whatever the last value you give can be
fractionated.  From the Wikipedia page you referenced:

"The smallest value used may also have a decimal fraction, as in
"P0.5Y" to indicate half a year."

> As you say, P1M really means one month and P1Y means one year. The
> ambiguity is intentional; if you mean to pay your employees monthly,
> the interval is one month.

True.  Your comment about monthly intervals makes me realize that you
probably can't map timedelta objects onto this ISO8601 duration
stuff. It seems like if you want to specify "pay my employees on the
first of every month", then timedelta objects are the wrong thing. You
want a recurrence relation, which is a more complex beast. For that,
you want something like dateutil.rrule. There is a good reason that
the internal units of timedelta objects are days, seconds, and
microseconds. They are well-defined outside of a calendar context.

So, I guess Roy is back to square one. He can always roll his own
timedelta subclass and give it a __str__ implementation...

S


From ian.g.kelly at gmail.com  Wed Mar 26 12:37:19 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 26 Mar 2014 10:37:19 -0600
Subject: unicode as valid naming symbols
In-Reply-To: <53329549.1000208@rece.vub.ac.be>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com> <53329549.1000208@rece.vub.ac.be>
Message-ID: <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>

On Wed, Mar 26, 2014 at 2:52 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> On 26-03-14 03:56, MRAB wrote:
>> Or as a root operator, e.g. 3 ? x (the cube root of x).
>>
> Personally I would think such an operator is too limited to include in a programming language.
> This kind of notation is only used with a constant to indicate what kind of root is taken and
> only with positive integers. Something like the equivallent of the following I have never seen.
>
>   t = 2.5
>   x = 8.2
>   y = t ? x

An example is taking the geometric mean of an arbitrary number of values:

    product = functools.reduce(operator.mul, values, 1)
    n = len(values)
    geometric_mean = n ? product

I might argue though for the inverted syntax (product ? n) to more
closely parallel division.


> Of course we don't have to follow mathematical convention with python. However allowing any
> unicode symbol as an identifier doesn't prohibit from using ? as an operator. We do have
> "in" and "is" as operators now, even if they would otherwise be acceptable identifiers.
> So I wonder, would you consider to introduce log as an operator. 2 log x seems an interesting
> operation for a programmer.

If it's going to become an operator, then it has to be a keyword.
Changing a token that is currently allowed to be an identifier into a
keyword is generally avoided as much as possible, because it breaks
backward compatibility.  "in" and "is" have both been keywords for a
very long time, perhaps since the initial release of Python.


From marko at pacujo.net  Wed Mar 26 13:13:44 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 26 Mar 2014 19:13:44 +0200
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8575.1395841035.18130.python-list@python.org>
 <1102ec6b-6205-40f4-bb7c-d40f9d13115b@googlegroups.com>
 <mailman.8581.1395848399.18130.python-list@python.org>
 <87a9cdx87t.fsf@elektro.pacujo.net>
 <mailman.8583.1395851680.18130.python-list@python.org>
Message-ID: <87a9ccopbr.fsf@elektro.pacujo.net>

Skip Montanaro <skip at pobox.com>:

> There is a good reason that the internal units of timedelta objects
> are days, seconds, and microseconds. They are well-defined outside of
> a calendar context.
>
> So, I guess Roy is back to square one. He can always roll his own
> timedelta subclass and give it a __str__ implementation...

If you don't want to mix the intricacies of calendars to datetime and
timedelta, why use them?

(Epoch) seconds do everything for you unambiguously.

Yes, yes. The physicists ought to stop fricking around with leap
seconds. They should declare a 3000-year moratorium on leap seconds.


Marko


From rustompmody at gmail.com  Wed Mar 26 13:32:04 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Wed, 26 Mar 2014 10:32:04 -0700 (PDT)
Subject: Delayed evaluation of expressions [was Re: Time we switched to
 unicode?]
In-Reply-To: <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
 <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8550.1395791763.18130.python-list@python.org>
 <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8562.1395808246.18130.python-list@python.org>
 <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <9ad6730a-f2d9-42fe-a822-88db2916972b@googlegroups.com>

On Wednesday, March 26, 2014 9:35:53 PM UTC+5:30, Steven D'Aprano wrote:
> On Wed, 26 Mar 2014 00:30:21 -0400, Terry Reedy wrote:

> > On 3/25/2014 8:12 PM, Steven D'Aprano wrote:
> >> On Tue, 25 Mar 2014 19:55:39 -0400, Terry Reedy wrote:
> >>> On 3/25/2014 11:18 AM, Steven D'Aprano wrote:
> >>>> The thing is, we can't just create a ? function, because it doesn't
> >>>> work the way the summation operator works. The problem is that we
> >>>> would want syntactic support, so we could write something like this:
> >>>>       p = 2
> >>>>       ?(n, 1, 10, n**p)
> >>> Of course we can. If we do not insist on separating the dummy name
> >>> from the expression that contains it. this works.
> >>> def sigma(low, high, func):
> >>>       sum = 0
> >>>       for i in range(low, high+1):
> >>>           sum += func(i)
> >>>       return sum
> >> There is no expression there. There is a function.
> >> You cannot pass an expression to a function in Python,
> > One passes an unquoted expression in code by quoting it with either
> > lambda, paired quote marks (Lisp used a single '), 

> Passing *strings* and *functions* is not the same as having compiler 
> support for delayed evaluation. At best its a second-class work-around. 
> Contrast:

Once the language has lambda, most else can be fashioned
See the classic papers 
lambda the ultimate imperative
lambda the ultimate declarative
lambda the ultimate goto
at here http://library.readscheme.org/page1.html

> Coincidentally, the Sum function we were discussing is a notable example 
> of Jensen's Device:

> https://en.wikipedia.org/wiki/Jensen%27s_device

> which is effectively what I'm referring to.

> >  > because expressions are not first-class objects.
> > The concept is not a class, and the Python stdlib does not have an
> > expression class. But people have written classes to represent the
> > concept. I used existing classes instead.
> > Expressions are not (normally) mathematical objects either. (An
> > exception is rewriting theory, or other theories, where strings
> > representing expressions or WFFs (well-formed formulas) are the only
> > objects.) Mathematicians quote expression strings by context or
> > positiion. The sigma form is one of many examples.

> Hmmm. I think you are misunderstanding me, possibly because I wrote 
> "first-class object" when I should have called it a "first-class value". 
> Sorry.

> I'm not necessarily referring to creating something like an "arithmetic 
> expression class" with methods and attributes. For example, sympy has 
> things like that, so you can perform symbolic operations on the 
> expression. That's not what I mean. 

> What I mean is that you, the programmer, writes down an ordinary Python 
> expression, using ordinary expression syntax, and the compiler treats it 
> as a value in and of itself, rather than evaluating it to find out what 
> value it has. In Python this will probably be some sort of object, but 
> that's not the important part. The important part is that it is a *value*.

> (Compare to languages where functions are not first-class values. You 
> cannot pass a function to another function, or stick them in a list, or 
> create them on the fly. You can only call them, evaluating them 
> immediately.)

> In Algol60, the compiler used thunks, which are a type of closure; in 
> CPython, list comps use a hidden function object; the ternary if compiles 
> byte code for a test and jump.

> In case you haven't read the article on Jensen's Device above, in Algol60 
> you can write a Sum function that behaves as a mathematician would 
> expect. For example, to sum the entries of an array V for indexes 1 
> through 100, a mathematician might write it something like this:

>     10
>     ? V[i]
>     i=1

> which we can rearrange to function-call syntax like this:

>     Sum(i, 1, 100, V[i])

> In Algol60, this function call would:

> - pass the name "i" (not a string!) as the first argument;
> - pass 1 as the second argument;
> - pass 100 as the third argument;
> - pass the expression "V[i]" (not a string!) as the fourth argument

> and then *inside* the function Sum the expressions "i" and "V[i]" can be 
> evaluated or assigned to as needed. Using Python syntax rather than Algol 
> syntax:

> def Sum(name, lower, upper, expression):
>     total = 0
>     for name in range(lower, upper+1):
>         total += expression
>     return total

> This doesn't work in Python! Python lacks call-by-name semantics, so the 
> function call would:

> - evaluate the expression i, and pass that value as the first argument;
> - pass 1 as the second argument;
> - pass 100 as the third argument;
> - evaluate V[i] and pass that value as the fourth argument

> and then inside the function Sum "name" refers to the local variable 
> name, not the caller's variable i. Likewise "expression" refers to a 
> local variable, and not the caller's expression V[i].

> Python has no general way of doing this. There are a few ad-hoc special 
> cases, like list comps, the ternary if operator, etc. which are hard-
> coded in the compiler to delay execution of expressions. For the rest, 
> you have a choice:

> - give up on delayed evaluation, and redesign your API; or

> - manually manage the delayed evaluation yourself, using
>   some combination of functions, eval or exec.

Heres Jensen device in python
First your pseudo algol version with python frills like range removed

def sumjensen(i,lower,upper,exp):
# i and exp by name
# i get and set, exp only get required
    tot = 0
    i = lower
    while i <= upper:
        tot += exp
        i = i + 1
    return tot

Now actual python

def sumjensen(i_get, i_set,lower,upper,exp):
    tot = 0
    i_set(lower)
    while i_get() <= upper:
        tot += exp_get()
        i_set(i_get() + 1)
    return tot


i=0
a=[3,4,5]
i_get = lambda : i
def i_set(val):
   global i
   i = val

exp_get = lambda : a[i_get()]


call as sumjensen(i_get, i_set, lower, upper, exp_get)

[Note that because of lambda's restriction to being only an expression
I have to make it a def because of need for  global]


From rustompmody at gmail.com  Wed Mar 26 13:57:52 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Wed, 26 Mar 2014 10:57:52 -0700 (PDT)
Subject: Delayed evaluation of expressions [was Re: Time we switched to
 unicode?]
In-Reply-To: <9ad6730a-f2d9-42fe-a822-88db2916972b@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
 <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8550.1395791763.18130.python-list@python.org>
 <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8562.1395808246.18130.python-list@python.org>
 <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <9ad6730a-f2d9-42fe-a822-88db2916972b@googlegroups.com>
Message-ID: <a24fbbf7-2748-4e65-95e0-5b4a0d5b7daf@googlegroups.com>

On Wednesday, March 26, 2014 11:02:04 PM UTC+5:30, Rustom Mody wrote:
> On Wednesday, March 26, 2014 9:35:53 PM UTC+5:30, Steven D'Aprano wrote:
> > On Wed, 26 Mar 2014 00:30:21 -0400, Terry Reedy wrote:
> > > One passes an unquoted expression in code by quoting it with either
> > > lambda, paired quote marks (Lisp used a single '), 

> > Passing *strings* and *functions* is not the same as having compiler 
> > support for delayed evaluation. At best its a second-class work-around. 
> > Contrast:

> Once the language has lambda, most else can be fashioned
> See the classic papers 
> lambda the ultimate imperative
> lambda the ultimate declarative
> lambda the ultimate goto
> at here http://library.readscheme.org/page1.html

<Details of Jensen implementation snipped>

Which I should have summarized as: lambda is the essential Delay operator.

So much so that in scheme

thaw and freeze are defined as

(using pseudo-python syntax)

def thaw(x) : return x()

freeze(x) is a 'special-form' (aka macro) such that

freeze(x) ? lambda : x


From invalid at invalid.invalid  Wed Mar 26 15:12:26 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Wed, 26 Mar 2014 19:12:26 +0000 (UTC)
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8575.1395841035.18130.python-list@python.org>
 <1102ec6b-6205-40f4-bb7c-d40f9d13115b@googlegroups.com>
 <mailman.8581.1395848399.18130.python-list@python.org>
 <87a9cdx87t.fsf@elektro.pacujo.net>
 <mailman.8583.1395851680.18130.python-list@python.org>
Message-ID: <lgv8qq$b0c$1@reader1.panix.com>

On 2014-03-26, Skip Montanaro <skip at pobox.com> wrote:
> On Wed, Mar 26, 2014 at 10:58 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> Fractions of seconds are supported -- the other fields can't be
>> fractional.
>
> Actually, it appears that whatever the last value you give can be
> fractionated.  From the Wikipedia page you referenced:

We're still just papering-over the basic problem: the entire
time/calendar system use by "western civilization" is a mess.  I don't
know a lot about other systems in use, but from what I have seen they
were all pretty much just as bad.  We should fix the basic problem
first, then I bet the Python library problems will sort themselves out
pretty easily.

Of course to simplify matters, we're going to have to stop worrying so
much about seasons and whether it's light or dark outside...

-- 
Grant Edwards               grant.b.edwards        Yow! Hey, wait
                                  at               a minute!!  I want a
                              gmail.com            divorce!! ... you're not
                                                   Clint Eastwood!!


From ben+python at benfinney.id.au  Wed Mar 26 16:06:17 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 27 Mar 2014 07:06:17 +1100
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8575.1395841035.18130.python-list@python.org>
 <1102ec6b-6205-40f4-bb7c-d40f9d13115b@googlegroups.com>
 <mailman.8581.1395848399.18130.python-list@python.org>
 <87a9cdx87t.fsf@elektro.pacujo.net>
 <mailman.8583.1395851680.18130.python-list@python.org>
 <lgv8qq$b0c$1@reader1.panix.com>
Message-ID: <85a9ccrah2.fsf@benfinney.id.au>

Grant Edwards <invalid at invalid.invalid> writes:

> We're still just papering-over the basic problem: the entire
> time/calendar system use by "western civilization" is a mess. I don't
> know a lot about other systems in use, but from what I have seen they
> were all pretty much just as bad. We should fix the basic problem
> first, then I bet the Python library problems will sort themselves out
> pretty easily.

I see from my calendar that 1 April is still several days away. So I
wonder how serious you are: we should forestall dealing with the reality
of calendars, until the world fixes our difficulties for us?

> Of course to simplify matters, we're going to have to stop worrying so
> much about seasons and whether it's light or dark outside...

Not too serious, I suppose.

So what *do* you recommend we do? It's easy to point at the real world
and say it's messy and distasteful to deal with, but that's a big part
of the job we take on as programmers.

-- 
 \            ?? Nature ? is seen to do all things Herself and through |
  `\         herself of own accord, rid of all gods.? ?Titus Lucretius |
_o__)                                                 Carus, c. 40 BCE |
Ben Finney



From ian.g.kelly at gmail.com  Wed Mar 26 17:19:03 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 26 Mar 2014 15:19:03 -0600
Subject: Dynamically reference variable in object
In-Reply-To: <cddebac0-8d5d-406f-8712-a9ce806a748d@googlegroups.com>
References: <d9daaeb5-04ef-43e8-b60e-3c4ba5790a9d@googlegroups.com>
 <cddebac0-8d5d-406f-8712-a9ce806a748d@googlegroups.com>
Message-ID: <CALwzidn2885wnBuFyF-4JhFQXeDVj8T_DSdDp0d17Jw2wLEM3w@mail.gmail.com>

On Mar 26, 2014 5:48 AM, "Ben Collier" <bmcollier at gmail.com> wrote:
>
> Sorry, subject was wrong. Please see below:
>
> On Wednesday, 26 March 2014 11:43:49 UTC, Ben Collier  wrote:
> > Hi all,
> > I know that I can dynamically reference a variable with locals()["i"],
for instance, but I'd like to know how to do this with a variable in an
object.
> > If I have an object called "device", with variables called attr1, attr2
.. attr50, how could I dynamically reference these?
> > It's fairly academic, but I'd like to avoid code duplication.

You want to access object "attributes", not "variables".  You can do this
using the functions getattr and setattr like so:

>>> class Foo(object): pass
...
>>> obj = Foo()
>>> setattr(obj, "x", 42)
>>> print(obj.x)
42
>>> print(getattr(obj, "x"))
42
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From jeanmichel at sequans.com  Wed Mar 26 05:53:16 2014
From: jeanmichel at sequans.com (Jean-Michel Pichavant)
Date: Wed, 26 Mar 2014 10:53:16 +0100 (CET)
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <roy-142548.20582725032014@news.panix.com>
Message-ID: <52552396.9136436.1395827596260.JavaMail.root@sequans.com>

----- Original Message -----
> One of my roles on this newsgroup is to periodically whine about
> stupidities in the Python datetime module.  This is one of those
> times.
> 
> I have some code which computes how long ago the sun set.  Being a
> nice
> pythonista, I'm using a timedelta to represent this value.  It would
> be
> difficult to imagine a less useful default way to print a timedelta:
> 
> previous sunset: -1 day, 22:25:26.295993
> 
> The idea of str() is that it's supposed to return a human-friendly
> representation of a value.  Humans do not say things like, "The sun
> set
> 1 day ago plus 22 hours and 25 minutes".

I can think of a less useful default way:

previous sunset: 1 sunset ago

This is how humans have been saying things for thousands of years before inventing the clock.
Beside that, I think datetime has all the formatters required to do pretty much anything.

Note : I don't see what's wrong in your example, however I have the feeling the term "stupiditie" is a little bit strong ;)

JM





-- IMPORTANT NOTICE: 

The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

From victor.engle at gmail.com  Wed Mar 26 11:46:35 2014
From: victor.engle at gmail.com (Victor Engle)
Date: Wed, 26 Mar 2014 11:46:35 -0400
Subject: datetime
Message-ID: <CABLWypNDCGcojSWR_Dp9NKJtEQH9cshgTZoY=7cm6Ye9_Ai73g@mail.gmail.com>

I want to keep a collection of data organized by collection date and I'll
use datetime like this...

>>> datetime.date.today()

datetime.date(2014, 3, 26)


I'll format the date and create directories like /mydata/yyyy-mm-dd


When I create a directory for today, I need to know the directory name for
yesterday and tomorrow. In perl I could get seconds since the epoch using
time and then add or subtract from that number for tomorrow or yesterday
and feed that into localtime to get the date string.


It would be convenient if  datetime.date.today() accepted an argument as an
offset from today, like datetime.date.today(-1). Is there an easy way to do
this with datetime?
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From cs at zip.com.au  Wed Mar 26 17:27:32 2014
From: cs at zip.com.au (Cameron Simpson)
Date: Thu, 27 Mar 2014 08:27:32 +1100
Subject: calling Python script from another Python script (Windows,
 multiple installation problem)
In-Reply-To: <6ba81449-5f4c-46be-ad4a-64ea8bc5b436@googlegroups.com>
References: <6ba81449-5f4c-46be-ad4a-64ea8bc5b436@googlegroups.com>
Message-ID: <20140326212732.GA33967@cskk.homeip.net>

On 26Mar2014 05:49, Martin Landa <landa.martin at gmail.com> wrote:
> Dne st?eda, 26. b?ezna 2014 13:29:47 UTC+1 Martin Landa napsal(a):
> > not really, I am just searching for a better solution based on virtualenv or something similar...
> 
> particularly I am using something like
> 
>         if sys.platform == "win32":
>             # get full path including file extension for scripts
>             fcmd = get_real_command(args[0]) 
>             if fcmd.endswith('.py'):
>                 args[0] = fcmd
>                 args.insert(0, sys.executable)
> 
> where 'args' in subprocess.Popen's argument. I just wonder if
> there is a better or preferable solution over this kind of a hack.

Personally, the above is what I would do in your situation.

Any solution involving virtualenv or the like will still need to
point at the right python executable. Provided your code above is
in a handy function, I wouldn't modify it.

What virtualenv (presumably a virtualenv bundled in your package)
_will_ give you is a stable and predictable collection of library
files to go with your python interpreter. That could well be a
significant benefit, especially in the face or an unknown target
machine.

So you may have a good case for putting a virtualenv in your bundle,
but still using the _same_ code above to invoke stuff - the python
in the virtualenv will set its sys.path, so the easy way is to
use your existing code to access the virtualenv python executable.

The only catch is that I do not know how mobile a virtualenv is;
if your bundle is unpacked in an unknown temporary location,
maybe virtualenv won't work correctly. Needs testing.

Disclaimer: I'm a UNIX guy.

Just my 2c. Hope it is helpful,
-- 
Cameron Simpson <cs at zip.com.au>

Carpe Datum     - John Sloan <jsloan at ncar.ucar.edu>


From __peter__ at web.de  Wed Mar 26 17:33:32 2014
From: __peter__ at web.de (Peter Otten)
Date: Wed, 26 Mar 2014 22:33:32 +0100
Subject: datetime
References: <CABLWypNDCGcojSWR_Dp9NKJtEQH9cshgTZoY=7cm6Ye9_Ai73g@mail.gmail.com>
Message-ID: <lgvh2t$1oo$1@ger.gmane.org>

Victor Engle wrote:

> I want to keep a collection of data organized by collection date and I'll
> use datetime like this...
> 
>>>> datetime.date.today()
> 
> datetime.date(2014, 3, 26)
> 
> 
> I'll format the date and create directories like /mydata/yyyy-mm-dd
> 
> 
> When I create a directory for today, I need to know the directory name for
> yesterday and tomorrow. In perl I could get seconds since the epoch using
> time and then add or subtract from that number for tomorrow or yesterday
> and feed that into localtime to get the date string.
> 
> 
> It would be convenient if  datetime.date.today() accepted an argument as
> an offset from today, like datetime.date.today(-1). Is there an easy way
> to do this with datetime?

>>> import datetime
>>> ONE_DAY = datetime.timedelta(days=1)
>>> today = datetime.date.today()
>>> today
datetime.date(2014, 3, 26)
>>> today - ONE_DAY
datetime.date(2014, 3, 25)
>>> today + ONE_DAY
datetime.date(2014, 3, 27)




From ben+python at benfinney.id.au  Wed Mar 26 17:36:42 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 27 Mar 2014 08:36:42 +1100
Subject: datetime
References: <CABLWypNDCGcojSWR_Dp9NKJtEQH9cshgTZoY=7cm6Ye9_Ai73g@mail.gmail.com>
Message-ID: <851txor6ad.fsf@benfinney.id.au>

Victor Engle <victor.engle at gmail.com> writes:

> It would be convenient if datetime.date.today() accepted an argument
> as an offset from today, like datetime.date.today(-1). Is there an
> easy way to do this with datetime?

The types defined in ?datetime? can perform calendar arithmetic::

    import datetime

    today = datetime.date.today()
    one_day = datetime.timedelta(days=1)
    yesterday = today - one_day
    tomorrow = today + one_day

<URL:http://docs.python.org/3/library/datetime.html#datetime.timedelta>

-- 
 \        ?Most people, I think, don't even know what a rootkit is, so |
  `\     why should they care about it?? ?Thomas Hesse, Sony BMG, 2006 |
_o__)                                                                  |
Ben Finney



From greg.ewing at canterbury.ac.nz  Wed Mar 26 18:08:47 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Thu, 27 Mar 2014 11:08:47 +1300
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <mailman.8578.1395843169.18130.python-list@python.org>
References: <roy-142548.20582725032014@news.panix.com>
 <5332DDE7.2050202@rece.vub.ac.be>
 <mailman.8578.1395843169.18130.python-list@python.org>
Message-ID: <bph1fdFnc3vU1@mid.individual.net>

Chris Angelico wrote:
> By showing those last ones as 1?.091... and 2?.091..., you emphasize
> the floating-point nature of the data: everything after the decimal is
> the mantissa, and everything before the decimal is the exponent.

The reason for writing them that way is so that you
can look the last part up in your log tables to
find the antilog.

I can't think of any corresponding justification
for timedeltas.

-- 
Greg


From rosuav at gmail.com  Wed Mar 26 18:24:49 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 27 Mar 2014 09:24:49 +1100
Subject: Delayed evaluation of expressions [was Re: Time we switched to
 unicode?]
In-Reply-To: <9ad6730a-f2d9-42fe-a822-88db2916972b@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <roy-66D138.23291924032014@news.panix.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
 <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8550.1395791763.18130.python-list@python.org>
 <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8562.1395808246.18130.python-list@python.org>
 <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <9ad6730a-f2d9-42fe-a822-88db2916972b@googlegroups.com>
Message-ID: <CAPTjJmo_HknLRQtq0sOVJ8KEnzQRdu+tz5X3n1i3hmp+e0Gf6A@mail.gmail.com>

On Thu, Mar 27, 2014 at 4:32 AM, Rustom Mody <rustompmody at gmail.com> wrote:
> Now actual python
>
> def sumjensen(i_get, i_set,lower,upper,exp):
>     tot = 0
>     i_set(lower)
>     while i_get() <= upper:
>         tot += exp_get()
>         i_set(i_get() + 1)
>     return tot
>
>
> i=0
> a=[3,4,5]
> i_get = lambda : i
> def i_set(val):
>    global i
>    i = val
>
> exp_get = lambda : a[i_get()]
>
>
> call as sumjensen(i_get, i_set, lower, upper, exp_get)
>
> [Note that because of lambda's restriction to being only an expression
> I have to make it a def because of need for  global]

You prove here that Python has first-class expressions in the same way
that 80x86 assembly language has garbage collection. Sure, you can
implement it using the primitives you have, but that's not support.

ChrisA


From marko at pacujo.net  Wed Mar 26 18:45:19 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 27 Mar 2014 00:45:19 +0200
Subject: Delayed evaluation of expressions
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
 <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8550.1395791763.18130.python-list@python.org>
 <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8562.1395808246.18130.python-list@python.org>
 <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <9ad6730a-f2d9-42fe-a822-88db2916972b@googlegroups.com>
 <mailman.8592.1395872698.18130.python-list@python.org>
Message-ID: <871txok29s.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> You prove here that Python has first-class expressions in the same way
> that 80x86 assembly language has garbage collection. Sure, you can
> implement it using the primitives you have, but that's not support.

I was more reminded of STL and Boost. For example:

   std::for_each(v.begin(), v.end(),
     ( 
       switch_statement(
         _1,
         case_statement<0>(std::cout << constant("zero")),
         case_statement<1>(std::cout << constant("one")),
         default_statement(cout << constant("other: ") << _1)
       ), 
       cout << constant("\n") 
     )
   );

(<URL: http://www.boost.org/doc/libs/1_55_0/doc/html/lambda/
le_in_details.html#lambda.switch_statement>)


Marko


From steve+comp.lang.python at pearwood.info  Wed Mar 26 19:42:22 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 26 Mar 2014 23:42:22 GMT
Subject: Dynamically reference variable in object
References: <d9daaeb5-04ef-43e8-b60e-3c4ba5790a9d@googlegroups.com>
 <cddebac0-8d5d-406f-8712-a9ce806a748d@googlegroups.com>
 <mailman.8586.1395868786.18130.python-list@python.org>
Message-ID: <533365de$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Wed, 26 Mar 2014 15:19:03 -0600, Ian Kelly wrote:

> You want to access object "attributes", not "variables".

In fairness to the OP, the terminology "instance variables" meaning 
attributes or members of an instance is (sadly, in my opinion) common in 
some other languages, such as Java, and occasionally creeps into even the 
Python docs.

I've often ranted about this, and won't repeat it now, only point out 
that the preferred and most common terminology in Python circles is 
"attribute", or "instance attribute" if you need to distinguish it from 
"class attribute".



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Wed Mar 26 19:43:21 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 26 Mar 2014 23:43:21 GMT
Subject: Delayed evaluation of expressions [was Re: Time we switched to
 unicode?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
 <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8550.1395791763.18130.python-list@python.org>
 <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8562.1395808246.18130.python-list@python.org>
 <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <9ad6730a-f2d9-42fe-a822-88db2916972b@googlegroups.com>
 <mailman.8592.1395872698.18130.python-list@python.org>
Message-ID: <53336618$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 27 Mar 2014 09:24:49 +1100, Chris Angelico wrote:

> On Thu, Mar 27, 2014 at 4:32 AM, Rustom Mody <rustompmody at gmail.com>
> wrote:
>> Now actual python
>>
>> def sumjensen(i_get, i_set,lower,upper,exp):
>>     tot = 0
>>     i_set(lower)
>>     while i_get() <= upper:
>>         tot += exp_get()
>>         i_set(i_get() + 1)
>>     return tot
>>
>>
>> i=0
>> a=[3,4,5]
>> i_get = lambda : i
>> def i_set(val):
>>    global i
>>    i = val
>>
>> exp_get = lambda : a[i_get()]
>>
>>
>> call as sumjensen(i_get, i_set, lower, upper, exp_get)
>>
>> [Note that because of lambda's restriction to being only an expression
>> I have to make it a def because of need for  global]
> 
> You prove here that Python has first-class expressions in the same way
> that 80x86 assembly language has garbage collection. Sure, you can
> implement it using the primitives you have, but that's not support.

+1


Any language can work around the lack of a language feature by sufficient 
layers of indirection, but that's not the same as having that language 
feature.

Beyond a certain minimum feature set, all languages are Turing complete, 
and so in one sense are of equivalent power. But they're not all of equal 
expressiveness. Python is awesome, it is very expressive, but there are 
certain things you can't write directly in Python, and have to resort to 
circumlocutions instead.

See also Paul Graham's "Blub language" essay:

http://paulgraham.com/avg.html




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ethan at stoneleaf.us  Wed Mar 26 19:33:50 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Wed, 26 Mar 2014 16:33:50 -0700
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <aco6j9ljgp9pipmcoisgf74rpmeptivebh@4ax.com>
References: <roy-142548.20582725032014@news.panix.com>
 <aco6j9ljgp9pipmcoisgf74rpmeptivebh@4ax.com>
Message-ID: <533363DE.2020604@stoneleaf.us>

On 03/26/2014 04:25 PM, Dennis Lee Bieber wrote:
> On Tue, 25 Mar 2014 20:58:27 -0400, Roy Smith <roy at panix.com> declaimed the
> following:
>
>> One of my roles on this newsgroup is to periodically whine about
>> stupidities in the Python datetime module.  This is one of those times.
>>
>> I have some code which computes how long ago the sun set.  Being a nice
>> pythonista, I'm using a timedelta to represent this value.  It would be
>> difficult to imagine a less useful default way to print a timedelta:
>>
>> previous sunset: -1 day, 22:25:26.295993
>>
>> The idea of str() is that it's supposed to return a human-friendly
>> representation of a value.  Humans do not say things like, "The sun set
>> 1 day ago plus 22 hours and 25 minutes".
>
> 	Makes sense to me -- the key being time DELTA... IE, a difference from
> some (unspecified) instance in time...
>
> 	If you want an instance of time, you need to add some known instance
> and the delta value.

Making sense is not the same as user friendly...

   "Hey, when did Bob get here?"

   "About 15 minutes ago."

vs

   "About an hour ago, plus 45 minutes."

--
~Ethan~


From steve+comp.lang.python at pearwood.info  Wed Mar 26 20:16:57 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 27 Mar 2014 00:16:57 GMT
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
Message-ID: <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Wed, 26 Mar 2014 19:25:45 -0400, Dennis Lee Bieber wrote:

> On Tue, 25 Mar 2014 20:58:27 -0400, Roy Smith <roy at panix.com> declaimed
> the following:
> 
>>One of my roles on this newsgroup is to periodically whine about
>>stupidities in the Python datetime module.  This is one of those times.
>>
>>I have some code which computes how long ago the sun set.  Being a nice
>>pythonista, I'm using a timedelta to represent this value.  It would be
>>difficult to imagine a less useful default way to print a timedelta:
>>
>>previous sunset: -1 day, 22:25:26.295993
>>
>>The idea of str() is that it's supposed to return a human-friendly
>>representation of a value.  Humans do not say things like, "The sun set
>>1 day ago plus 22 hours and 25 minutes".
> 
> 	Makes sense to me -- the key being time DELTA... IE, a difference 
> from some (unspecified) instance in time...
> 
> 	If you want an instance of time, you need to add some known 
> instance and the delta value.


I think you have missed the point of the rant. Roy is not ranting that he 
has a timedelta. He wants a timedelta. He is ranting that the timedelta 
displays in a totally unintuitive fashion. Paraphrasing:

"the previous sunset was (one day less 22 hours and 25 minutes) ago"

instead of 

"the previous sunset was (1 hour and 35 minutes) ago"

where the parts in the brackets come directly from the timedelta object.

I think that you misread Roy's example as:

"1 day plus 22 hours 25 minutes ago"

instead of:

"1 day ago plus 22 hours 25 minutes"

(that is, 22 hours and 25 minutes after 1 day ago).

The problem here, I believe, is that there are two ways of interpreting 
remainders for negative numbers. Dividing -5 by 2 can give either -2 with 
remainder -1, or -3 with remainder +1.

Mathematically, it is *usually* more useful to go with the version with 
the positive remainder, and that's what Python does. But I think it's the 
wrong choice for timedelta. Let's take a simple example: a timedelta of 
30 hours. What's that in days and hours?

py> divmod(30, 24)
(1, 6)

That makes perfect intuitive sense: 30 hours is 1 day with 6 hours 
remaining. In human-speak, we'll say that regardless of whether the 
timedelta is positive or negative: we'll say "1 day and 6 hours from now" 
or "1 day and 6 hours ago". But when we specify the sign:

py> divmod(-30, 24)
(-2, 18)

If an event happened 30 hours ago, it is correct to say that it occurred 
"18 hours after 2 days ago", but who talks that way?




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From tjreedy at udel.edu  Wed Mar 26 20:44:17 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 26 Mar 2014 20:44:17 -0400
Subject: Delayed evaluation of expressions [was Re: Time we switched to
 unicode?]
In-Reply-To: <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8485.1395719463.18130.python-list@python.org>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
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 <mailman.8562.1395808246.18130.python-list@python.org>
 <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lgvs8u$45t$1@ger.gmane.org>

I agree that we have not been understanding each other.

 From you original post that I responded to:
>>>>> The thing is, we can't just create a ? function, because it doesn't
>>>>> work the way the summation operator works. The problem is that we
>>>>> would want syntactic support, so we could write something like this:
 >>>>>        p = 2
 >>>>>        ?(n, 1, 10, n**p)

The initial misunderstanding is that I interpreted 'something like this' 
more loosely than you meant it. So I wrote something that was 'something 
like the above' to me but not to you. I interpreted 'something like' 
semantically* whereas you apparently meant is syntactically. I added the 
one or the other little marks needed to make the above work in python as 
it is whereas your 'something like' excludes such marks or any other 
current possibility I can think of. So I actually agree that "can't" is 
correct in relation to what you meant, as opposed to what I understood.

Changing "can't" to "can" would requires a major change to Python. That 
change is one I would strongly oppose and I will try to explain more 
clearly why.

[*When I qualify doc suggestions on the tracker with 'something like', 
as I usually do, I mean something that conveys the same meaning. So I 
edited your call text to convey the intended meaning in Python.]

Lets start with things we should agree on.  The first two are mostly not 
specific to Python.

1. When a compiler encounters an expression in code, there are at least 
three things it can do:
1a. compile it so that it is immediately executed when encountered at 
runtime (let this be the default);
1b. compile it so that it is somehow saved for execution later or 
elsewhere (the alternative of concern here);
1c. compile it for a different alternative, such as turning an implied 
'get' operation into a 'set' operation.

2. A code writer who wants an alternative treatment for a particular 
must somehow delineate the expresion with boundary markers that, in 
context at least, also indicate the alternative treatment. There are, 
broadly, two possibilities:
2a. Use a generic quotation mechanism that can be applied to any 
expression most any place. I call this explicit quoting.
2b. Use the expression in a special form that the compiler knows about. 
The special form must have begin-end markers of some sort. I call this 
implicit quoting. If human readers do not know that a particular form is 
a special form, they may have a problem understanding the code.

Python has 2 pairs of generic explicit delimiters: open-close quote 
marks and lambda-<EndofLambda>, where <EndofLambda> is ',', ')', 
<EndofLine>, or maybe something else. If these are not present, the 
default immediate execution mode is used for expressions in function 
calls that are not themselves marked for alternative treatment.

Python's special forms are statements. Each has its own pair of 
delimiters. Assignments use <BeginningofLine> and '='. 'For' loops use 
'for' and 'in'. Other statements use 'as' and usually <EndofLine>.

Statements and functions call are syntactically very distinct, so there 
is little possibility of confusion. I consider this a major feature of 
python and I would oppose breaking it.

Lisp, for instance, uses s-expressions for everything, including what 
would either function calls or statements in Python. Special functions 
implicitly quote some argument expressions, but not necessarily all, 
while normal functions do not quote any. The only way to know is to 
know, and I found it confusing and difficult to remember.

 > Sum(i, 1, 100, V[i])
 > In Algol60, this function call would:

 > - pass the name "i" (not a string!) as the first argument;
 > - pass 1 as the second argument;
 > - pass 100 as the third argument;
 > - pass the expression "V[i]" (not a string!) as the fourth argument

which depends for this operation on

 > https://en.wikipedia.org/wiki/Jensen%27s_device

I read the whole article, including the criticisms and the fact that it 
was not widely adopted and has been more or less superceded by macros. 
It did not answer the obvious question: suppose the call is Sum(i, l, h, 
V[i]). How is the reader supposed to know that 'i' and 'V[i]' get quoted 
and the other args do not?  The article included

  real procedure Sum(k, l, u, ak)
       value l, u;
       integer k, l, u;
       real ak;
       comment k and ak are passed by name;
    begin
       real s;
       s := 0;
       for k := l step 1 until u do
          s := s + ak;
       Sum := s
    end;

If that is supposed to be real code that can be compiled, I see no way 
for the comment to be true. Or is the mechanism limited to builtin 
functions?

-- 
Terry Jan Reedy




From rhodri at wildebst.org.uk  Wed Mar 26 21:01:52 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Thu, 27 Mar 2014 01:01:52 -0000
Subject: python installation on windows
References: <04f1a2d3-4d34-4871-a845-1301cda1c19c@googlegroups.com>
 <op.xc7fkg2m5079vu@gnudebeest>
 <f154fd7a-30c2-4165-8c9c-6441f15a1fa4@googlegroups.com>
 <96fa02bf-7c6d-4b12-8791-d640d5910173@googlegroups.com>
Message-ID: <op.xdcvtecm5079vu@gnudebeest>

On Tue, 25 Mar 2014 18:17:30 -0000, <rborole06 at gmail.com> wrote:

>> Thanks for your comment but i also edited httpd.conf file then my wamp  
>> not running
>>
>> LoadModule php5_module "c:/wamp/bin/php/php5.3.0/php5apache2_2.dll"
>>
>> This line i added on line 128 but nothing. Wampserver showing yellow.
>>
>> I'm not getting what happening. I'm doing as per suggested in  
>> documentation
>>
>
> And again if i'm removing this line then wampserver works properly

I'm totally confused.  You started out asking about problems getting  
mod_wsgi to load, and now without any indication that you've actually got  
mod_wsgi to load you are asking a Python group about a PHP module.  Slow  
down, do one thing at a time and please don't assume that we can read your  
mind.

Also please read https://wiki.python.org/moin/GoogleGroupsPython and take  
appropriate action.  This post was unreadable when it got to me, and I  
nearly didn't bother putting in the effort to make it readable.

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From nispray at gmail.com  Wed Mar 26 21:04:33 2014
From: nispray at gmail.com (Wesley)
Date: Wed, 26 Mar 2014 18:04:33 -0700 (PDT)
Subject: gdb python how to output integer for examine memory
In-Reply-To: <mailman.8563.1395817836.18130.python-list@python.org>
References: <e1e8c3a2-5d8d-4aae-9a5d-82af79be8c4c@googlegroups.com>
 <mailman.8505.1395733762.18130.python-list@python.org>
 <2aa794ce-7cc1-4d24-a30b-3fb17b89e33f@googlegroups.com>
 <mailman.8563.1395817836.18130.python-list@python.org>
Message-ID: <241236ba-029a-4206-b5a1-f60bd19e56c9@googlegroups.com>

? 2014?3?26????UTC+8??3?10?23??dieter???
> Wesley <nispray at gmail.com> writes:
> 
> > ...
> 
> > Actually, I can now see the varialbe names at Python level and C level.
> 
> > I just want to verify x command to monitor the memory content.
> 
> > So, in my origin post, I can get variable i's address, and see the value is 1,
> 
> > then, I wanna have a try x command, the issue is, when use x/format i's address, the output is not 1, but other things:-(
> 
> 
> 
> All Python objects start (at C level) with a header (containing
> 
> the reference count, a pointer to the associated type and
> 
> maybe other things); the "real" value starts behind this header.
> 
> 
> 
> This means, to see the "1" in your example, you must skip the
> 
> associated object header -- either in the output or by adding
> 
> the size of the header to the initial address.

Most like this.
I will try later.


From rhodri at wildebst.org.uk  Wed Mar 26 21:16:48 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Thu, 27 Mar 2014 01:16:48 -0000
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
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 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <a434e0d3-b2e1-400d-a9a2-ac35493c2c4a@googlegroups.com>
 <mailman.8486.1395719831.18130.python-list@python.org>
 <53311887$0$2756$c3e8da3$76491128@news.astraweb.com>
 <mailman.8497.1395727978.18130.python-list@python.org>
Message-ID: <op.xdcwiatd5079vu@gnudebeest>

On Tue, 25 Mar 2014 06:12:50 -0000, Chris Angelico <rosuav at gmail.com>  
wrote:

> Because the shorter symbols lend themselves better to the
> "super-tokenization" where you don't read the individual parts but the
> whole. The difference between "40" and "forty" is minimal, but the
> difference between "86400" and "eighty-six thousand [and] four
> hundred" is significant; the first is a single token, which you could
> then instantly recognize as the number of seconds in a day (leap
> seconds aside), but the second is a lengthy expression.

It's not quite that simple, sadly (for me).  I have mild dyscalculia,  
which in my case is another way of saying that collections of digits  
*aren't* tokens to me unless I ascribe a specific meaning to them.  I  
don't work with day-level time differences a lot, so 86400 is just a  
string of digits to me.  Powers of two and one less than powers of two I  
use a lot, so 65535 for example is a token.  The more digits there are in  
the number, the harder it is for me to take in in a way that doesn't  
happen with letters.  Even "forty" is better than "40" if you want me to  
recall it!

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From rosuav at gmail.com  Wed Mar 26 21:26:21 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 27 Mar 2014 12:26:21 +1100
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <op.xdcwiatd5079vu@gnudebeest>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
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Message-ID: <CAPTjJmpt7Dn9NfqAX8xeDzDhR3DxbFRs2YATDt+1=DNVW8nocw@mail.gmail.com>

On Thu, Mar 27, 2014 at 12:16 PM, Rhodri James <rhodri at wildebst.org.uk> wrote:
> It's not quite that simple, sadly (for me).  I have mild dyscalculia, which
> in my case is another way of saying that collections of digits *aren't*
> tokens to me unless I ascribe a specific meaning to them.  I don't work with
> day-level time differences a lot, so 86400 is just a string of digits to me.
> Powers of two and one less than powers of two I use a lot, so 65535 for
> example is a token.  The more digits there are in the number, the harder it
> is for me to take in in a way that doesn't happen with letters.  Even
> "forty" is better than "40" if you want me to recall it!

Interesting. This suggests that your brain works happily with words
(since you can recall "forty" more easily), but not with digits.

But even in the normal case, that will be true to some extent. It's
common to break up long numbers into groups of three or four digits -
look at credit cards and phone numbers, for two very common examples.
Treating 86400 as a single token comes more easily when you know it's
the number of seconds in a day, and recognizing 604800 as the number
of seconds in a week is pretty much essential to seeing it as a single
token.

ChrisA


From rosuav at gmail.com  Wed Mar 26 21:28:43 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 27 Mar 2014 12:28:43 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmoni_wQHdaA1tLNS-F6Dsynq1gpnaRFngNsBXOvgEjM0Q@mail.gmail.com>

On Thu, Mar 27, 2014 at 11:16 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> If an event happened 30 hours ago, it is correct to say that it occurred
> "18 hours after 2 days ago", but who talks that way?

That response demonstrates real genius. Rue the datetime? Who talks like that?

ChrisA


From roy at panix.com  Wed Mar 26 21:38:32 2014
From: roy at panix.com (Roy Smith)
Date: Wed, 26 Mar 2014 21:38:32 -0400
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8597.1395883727.18130.python-list@python.org>
Message-ID: <roy-34E0D7.21383226032014@news.panix.com>

In article <mailman.8597.1395883727.18130.python-list at python.org>,
 Chris Angelico <rosuav at gmail.com> wrote:

> On Thu, Mar 27, 2014 at 11:16 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
> > If an event happened 30 hours ago, it is correct to say that it occurred
> > "18 hours after 2 days ago", but who talks that way?
> 
> That response demonstrates real genius. Rue the datetime? Who talks like that?

"I had a dangling pointer error, and blew my stack to half past last 
wednesday"


From rustompmody at gmail.com  Wed Mar 26 21:59:33 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Wed, 26 Mar 2014 18:59:33 -0700 (PDT)
Subject: Delayed evaluation of expressions [was Re: Time we switched to
 unicode?]
In-Reply-To: <53336618$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
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 <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <9ad6730a-f2d9-42fe-a822-88db2916972b@googlegroups.com>
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 <53336618$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <169b5e45-f911-47c2-996b-0507d78dd7d1@googlegroups.com>

On Thursday, March 27, 2014 5:13:21 AM UTC+5:30, Steven D'Aprano wrote:
> On Thu, 27 Mar 2014 09:24:49 +1100, Chris Angelico wrote:

> > wrote:
> >> Now actual python
> >> def sumjensen(i_get, i_set,lower,upper,exp):
> >>     tot = 0
> >>     i_set(lower)
> >>     while i_get() <= upper:
> >>         tot += exp_get()
> >>         i_set(i_get() + 1)
> >>     return tot
> >> i=0
> >> a=[3,4,5]
> >> i_get = lambda : i
> >> def i_set(val):
> >>    global i
> >>    i = val
> >> exp_get = lambda : a[i_get()]
> >> call as sumjensen(i_get, i_set, lower, upper, exp_get)
> >> [Note that because of lambda's restriction to being only an expression
> >> I have to make it a def because of need for  global]
> > You prove here that Python has first-class expressions in the same way
> > that 80x86 assembly language has garbage collection. Sure, you can
> > implement it using the primitives you have, but that's not support.

> +1

> Any language can work around the lack of a language feature by sufficient 
> layers of indirection, but that's not the same as having that language 
> feature.

> Beyond a certain minimum feature set, all languages are Turing complete, 
> and so in one sense are of equivalent power. But they're not all of equal 
> expressiveness. Python is awesome, it is very expressive, but there are 
> certain things you can't write directly in Python, and have to resort to 
> circumlocutions instead.

Of course.

And there are different grades of circumlocution -- of 'coding-up' --
a missing feature.


Terry said:
> One passes an unquoted expression in code by quoting it with either
> lambda, paired quote marks (Lisp used a single '),

Steven responded:
> Passing *strings* and *functions* is not the same as having compiler
> support for delayed evaluation. At best its a second-class work-around. 

I was merely pointing out that 'passing strings' and 'passing functions'
as 'coding-up' of some desirable but unavailable feature are very different
levels of work-around.

In fact there are actually 3 styles and levels of circumlocution

1. You dont have a certain language -- blub?? -- feature set.
So... code it up and write its interpreter as eval_blub.

2. You dont have a feature-set but can see similarity in some obtuse
host-language (in this case python).
So you code up a mini-translator for your feature-set neatly written to obtuse 
hostly written and then eval (note python eval not blub eval)

3. You dont go outside the language framework and into any eval-ish
mode at all.  Good ol subroutine libraries to classes for abstraction
to first-class functional abstraction -- all fall into this category



From steve+comp.lang.python at pearwood.info  Wed Mar 26 22:16:14 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 27 Mar 2014 02:16:14 GMT
Subject: Delayed evaluation of expressions [was Re: Time we switched to
 unicode?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgquvt$b7t$1@speranza.aioe.org>
 <281c8ce1-4f03-4e93-b5cd-d45b85e89e7e@googlegroups.com>
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 <mailman.8595.1395881083.18130.python-list@python.org>
Message-ID: <533389ed$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Wed, 26 Mar 2014 20:44:17 -0400, Terry Reedy wrote:

> I agree that we have not been understanding each other.
> 
>  From you original post that I responded to:
>>>>>> The thing is, we can't just create a ? function, because it doesn't
>>>>>> work the way the summation operator works. The problem is that we
>>>>>> would want syntactic support, so we could write something like
>>>>>> this:
>  >>>>>        p = 2
>  >>>>>        ?(n, 1, 10, n**p)
> 
> The initial misunderstanding is that I interpreted 'something like this'
> more loosely than you meant it. So I wrote something that was 'something
> like the above' to me but not to you. I interpreted 'something like'
> semantically* whereas you apparently meant is syntactically. I added the
> one or the other little marks needed to make the above work in python as
> it is whereas your 'something like' excludes such marks or any other
> current possibility I can think of. So I actually agree that "can't" is
> correct in relation to what you meant, as opposed to what I understood.
> 
> Changing "can't" to "can" would requires a major change to Python. That
> change is one I would strongly oppose and I will try to explain more
> clearly why.

I'm not making a serious proposal to change Python's behaviour. In 
context, this came up because I said that allowing arbitrary maths 
symbols in Python wouldn't work, because you can't get the behaviour 
right, and used the example of ?(n, 1, 10, n**p) as something where the 
behaviour would be different from what a mathematician would like. Given 
that the semantics would be so different, there's little point in trying 
to match the symbol ? too. Just write it as sum() in the Pythonic style. 
Python is not Mathematica. (However, you could, perhaps, write 
Mathematica in Python.)

That was the context of introducing delayed evaluation to the discussion. 
But having raised it, I do think it is an important and useful feature. 
Python already has it in various ad hoc places, such as list comps and 
generator expressions, ternary if, and/or, and it came up again recently 
in the PEP for try...except expressions. It doesn't happen every day, but 
there is a steady trickle of requests (some successful, some not) for 
compiler support for something that includes delaying the evaluation of 
some expression until later. Some day, if all the pieces come into place, 
I may make a serious proposal for a generic mechanism for delaying 
execution of expressions. But that is not this day.

[...]
> Lets start with things we should agree on.  The first two are mostly not
> specific to Python.
> 
> 1. When a compiler encounters an expression in code, there are at least
> three things it can do:
> 1a. compile it so that it is immediately executed when encountered at
> runtime (let this be the default);
> 1b. compile it so that it is somehow saved for execution later or
> elsewhere (the alternative of concern here); 
> 1c. compile it for a different alternative, such as turning an implied
> 'get' operation into a 'set' operation.

I don't actually understand what 1c is, or rather I understand what you 
mean, I don't understand why a compiler would do that. But I don't think 
it is important, so carry on.


> 2. A code writer who wants an alternative treatment for a particular
> must somehow delineate the expresion with boundary markers that, in
> context at least, also indicate the alternative treatment.

Not necessarily. That's not how it works in Pascal and Algol. In the case 
of Algol, argument passing is pass-by-name unless declared otherwise. In 
the case of Pascal, expressions are always evaluated first (pass-by-
value), except for one special case: if the expression consists of a 
single name, AND the function declares the parameter to be a "var" 
parameter, Pascal uses pass-by-reference, which you can think of as 
conceptually like a cut-down restricted version of pass-by-name.

But the point is that the decision whether to evaluate the expression 
immediately or not could be up to the compiler, not the caller. In fact, 
that's what Python already does:

    mylist and mylist[0]


always delays evaluation of the second clause, the caller doesn't have to 
do anything special except to ensure she writes them in the right order.

The problem with the Pascal approach, where the function declares what 
calling mechanism to use, is that this needs the function to be known at 
compile time so that the compiler knows what mechanism to use to pass the 
argument into the function. As far as I know, the languages which offer a 
choice of calling convention (Pascal, Basic?) have static function 
declarations known at compile-time. I'm not sure about Perl.

Anyway, the point is that in principle there is another mechanism: the 
compiler knows whether to delay evaluation or not, and the caller has no 
say in it.


> There are, broadly, two possibilities:
> 2a. Use a generic quotation mechanism that can be applied to any
> expression most any place. I call this explicit quoting. 

Skipping ahead:

> Python has 2 pairs of generic explicit delimiters: open-close quote
> marks and lambda-<EndofLambda>, where <EndofLambda> is ',', ')',
> <EndofLine>, or maybe something else. If these are not present, the
> default immediate execution mode is used for expressions in function
> calls that are not themselves marked for alternative treatment.

I think that's a misuse of terminology and badly missing the point. If 
you have to *manually* manage this process yourself, by writing a 
function, or calling eval() on a string, it's not a feature of the 
language. Saying that Python has a generic mechanism for delaying 
execution of an expression ("put it in a function, or use a string and 
eval() the string later") is like saying that C has garbage collection 
("just keep track of which pointers you are or aren't using yourself").

Given the lack of such delayed execution, a reasonable work-around may 
sometimes be to use a function. But it's not the same. If language 
features weren't important, we'd all be using FORTRAN I exactly as it was 
in the 1950s.


> 2b. Use the
> expression in a special form that the compiler knows about. The special
> form must have begin-end markers of some sort. 

That's incorrect, unless you think "Start Of Expression" and "End Of 
Expression" are markers.


> I call this implicit
> quoting. If human readers do not know that a particular form is a
> special form, they may have a problem understanding the code.

Um, yes? If you don't know the semantics of the language you are reading, 
any language, you're going to have trouble understanding it. If I see:

mylist = [1, 2, 3, 4, 5]*10000000
for i in range(30):
    print function(mylist, i)


and I don't know how Python works, I might say "ZOMG! That has to walk a 
fifty-million item linked list thirty times, copying it each time it is 
passed to the function! How inefficient!". And I would be wrong.

We're allowed to suppose that Python programmers are aware that lists 
aren't linked-lists, and that passing a list to a function does not copy 
it. We're allowed to suppose that Python programmers know that the 1/x 
expression in `1/x if x != 0 else y` is not evaluated unless x is non-
zero. If there is a syntactic form that delays evaluation, like and/or 
delay evaluation, we're allowed to presume the programmer knows that this 
is what it does.



> Python's special forms are statements. Each has its own pair of
> delimiters. Assignments use <BeginningofLine> and '='. 'For' loops use
> 'for' and 'in'. Other statements use 'as' and usually <EndofLine>.

Not always. You've missed ternary if, and, or, list comprehensions and 
generator expressions, all of which are expressions, not statements.

Python can delay execution of an expression within another expression. 
It's just that so far, they have to be specially treated by the compiler. 
There's no generic mechanism for this.


> Statements and functions call are syntactically very distinct, so there
> is little possibility of confusion. I consider this a major feature of
> python and I would oppose breaking it.

I'm not sure if this is relevant or not.


> Lisp, for instance, uses s-expressions for everything, including what
> would either function calls or statements in Python. Special functions
> implicitly quote some argument expressions, but not necessarily all,
> while normal functions do not quote any. The only way to know is to
> know, and I found it confusing and difficult to remember.
> 
>  > Sum(i, 1, 100, V[i])
>  > In Algol60, this function call would:
> 
>  > - pass the name "i" (not a string!) as the first argument; - pass 1
>  > as the second argument;
>  > - pass 100 as the third argument;
>  > - pass the expression "V[i]" (not a string!) as the fourth argument
> 
> which depends for this operation on
> 
>  > https://en.wikipedia.org/wiki/Jensen%27s_device
> 
> I read the whole article, including the criticisms and the fact that it
> was not widely adopted and has been more or less superceded by macros.
> It did not answer the obvious question: suppose the call is Sum(i, l, h,
> V[i]). How is the reader supposed to know that 'i' and 'V[i]' get quoted
> and the other args do not?

They infer it from the usage.

(Python example: given that you can write "mylist and mylist[0]", and it 
does not raise IndexError when mylist is empty, so we can infer that the 
second term "mylist[0]" is not evaluated unless the first is true.)

Or they read the docs of the Sum function. Or both.


> The article included
> 
>   real procedure Sum(k, l, u, ak)
>        value l, u;
>        integer k, l, u;
>        real ak;
>        comment k and ak are passed by name;
>     begin
>        real s;
>        s := 0;
>        for k := l step 1 until u do
>           s := s + ak;
>        Sum := s
>     end;
> 
> If that is supposed to be real code that can be compiled, I see no way
> for the comment to be true. Or is the mechanism limited to builtin
> functions?

Pass-by-name is the default argument passing mechanism in Algol 60. The 
middle two parameters, l and u, are declared as pass-by-value in the 
second line. That means that k and ak use the default mechanism, which is 
pass by name.

Because functions in Algol 60 are statically determined at compile time, 
the compiler now knows how to pass arguments into the Sum function. I 
don't know how you would do that in a language like Python where the 
function is not statically known at compile time.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From bjlockie at lockie.ca  Wed Mar 26 23:23:29 2014
From: bjlockie at lockie.ca (James Smith)
Date: Wed, 26 Mar 2014 20:23:29 -0700 (PDT)
Subject: regex line by line over file
Message-ID: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>

I can't get this to work.
It runs but there is no output when I try it on a file.


#!/usr/bin/python

import os
import sys
import re
from datetime import datetime

#logDir = '/nfs/projects/equinox/platformTools/RTLG/RTLG_logs';
#os.chdir( logDir );

programName = sys.argv[0]
fileName = sys.argv[1]

#pattern = re.compile('\s*\\"SHELF-.*,SC,.*,:\\"Log Collection In Progress\\"')
re.M
p = re.compile('^\s*\"SHELF-.*,SC,.*,:\\\"Log Collection In Progress\\\"')
l = '    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\"Log Collection In Progress\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"'

# this works :-)
m = p.match( l )
if m:
    print( l )

# this doesn't match anything (or the if doesn't work) :-(
with open(fileName) as f:
    for line in f:
        # debug code (print the line without adding a linefeed)
        # sys.stdout.write( line )
        if p.match(line):
            print(line)


The test file just has one line:
    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\"Log Collection In Progress\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"


From rosuav at gmail.com  Wed Mar 26 23:42:39 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 27 Mar 2014 14:42:39 +1100
Subject: regex line by line over file
In-Reply-To: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>
References: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>
Message-ID: <CAPTjJmr-2K0t4d217+TWm=a8xFNwMETrqUFLERPuSFh+w77A8g@mail.gmail.com>

On Thu, Mar 27, 2014 at 2:23 PM, James Smith <bjlockie at lockie.ca> wrote:
> re.M
> p = re.compile('^\s*\"SHELF-.*,SC,.*,:\\\"Log Collection In Progress\\\"')

If you're expecting this to be parsed as a multiline regex, it won't
be. Probing re.M doesn't do anything on its own; you have to pass it
as an argument to compile.

Not sure if that's your problem or not, though.

ChrisA


From dan at tombstonezero.net  Wed Mar 26 23:56:39 2014
From: dan at tombstonezero.net (Dan Sommers)
Date: Thu, 27 Mar 2014 03:56:39 +0000 (UTC)
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh07hn$pii$1@dont-email.me>

On Thu, 27 Mar 2014 00:16:57 +0000, Steven D'Aprano wrote:

> py> divmod(-30, 24)
> (-2, 18)
> 
> If an event happened 30 hours ago, it is correct to say that it
> occurred "18 hours after 2 days ago", but who talks that way?

Well, not *exactly*, but:

If today happens to be Wednesday, and an event occurred last Friday, I
might say "a week ago Friday."  Similarly, today, I could also say
"it'll be two years at my new job next month."

For an event that occurred approximately 310 days ago, I might say "less
than a year ago," and for an event that occurred approximately 350 days
ago, I might say "a little less than a year ago."

Or did you forget to put the winky there, and I fell for it?

11 years, 2 months, 26 days, 9 hours, 3 minutes, 27.4 seconds'ly yours,
Dan



From bjlockie at lockie.ca  Thu Mar 27 00:14:03 2014
From: bjlockie at lockie.ca (James Smith)
Date: Wed, 26 Mar 2014 21:14:03 -0700 (PDT)
Subject: regex line by line over file
In-Reply-To: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>
References: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>
Message-ID: <a79bc9f2-eb49-4037-9e1a-eb234dca12d5@googlegroups.com>

On Wednesday, March 26, 2014 11:23:29 PM UTC-4, James Smith wrote:
> I can't get this to work.
> 
> It runs but there is no output when I try it on a file.
> 
> 
> 
> 
> 
> #!/usr/bin/python
> 
> 
> 
> import os
> 
> import sys
> 
> import re
> 
> from datetime import datetime
> 
> 
> 
> #logDir = '/nfs/projects/equinox/platformTools/RTLG/RTLG_logs';
> 
> #os.chdir( logDir );
> 
> 
> 
> programName = sys.argv[0]
> 
> fileName = sys.argv[1]
> 
> 
> 
> #pattern = re.compile('\s*\\"SHELF-.*,SC,.*,:\\"Log Collection In Progress\\"')
> 
> re.M
> 
> p = re.compile('^\s*\"SHELF-.*,SC,.*,:\\\"Log Collection In Progress\\\"')
> 
> l = '    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\"Log Collection In Progress\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"'
> 
> 
> 
> # this works :-)
> 
> m = p.match( l )
> 
> if m:
> 
>     print( l )
> 
> 
> 
> # this doesn't match anything (or the if doesn't work) :-(
> 
> with open(fileName) as f:
> 
>     for line in f:
> 
>         # debug code (print the line without adding a linefeed)
> 
>         # sys.stdout.write( line )
> 
>         if p.match(line):
> 
>             print(line)
> 
> 
> 
> 
> 
> The test file just has one line:
> 
>     "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\"Log Collection In Progress\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"

I tried the re.M in the compile and that didn't help.


From rustompmody at gmail.com  Thu Mar 27 00:37:35 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Wed, 26 Mar 2014 21:37:35 -0700 (PDT)
Subject: regex line by line over file
In-Reply-To: <a79bc9f2-eb49-4037-9e1a-eb234dca12d5@googlegroups.com>
References: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>
 <a79bc9f2-eb49-4037-9e1a-eb234dca12d5@googlegroups.com>
Message-ID: <3e8e2912-91a9-4762-aec6-fd89a77cc484@googlegroups.com>

On Thursday, March 27, 2014 8:53:29 AM UTC+5:30, James Smith wrote:
> I can't get this to work.
> It runs but there is no output when I try it on a file.

> #!/usr/bin/python

> import os
> import sys
> import re
> from datetime import datetime

> #logDir = '/nfs/projects/equinox/platformTools/RTLG/RTLG_logs';
> #os.chdir( logDir );

> programName = sys.argv[0]
> fileName = sys.argv[1]

> #pattern = re.compile('\s*\\"SHELF-.*,SC,.*,:\\"Log Collection In Progress\\"')
> re.M
> p = re.compile('^\s*\"SHELF-.*,SC,.*,:\\\"Log Collection In Progress\\\"')
> l = '    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\"Log Collection In Progress\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"'

> # this works :-)
> m = p.match( l )
> if m:
>     print( l )

> # this doesn't match anything (or the if doesn't work) :-(
> with open(fileName) as f:
>     for line in f:
>         # debug code (print the line without adding a linefeed)
>         # sys.stdout.write( line )
>         if p.match(line):
>             print(line)

> The test file just has one line:
>     "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\"Log Collection In Progress\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"

Some suggestions (Im far from an re expert!)
1. Use raw strings for re's
2. You probably need non-greedy '*' (among other things)
3. Better to hack out your re in the interpreter
For that
4. Avoid compile (at least while hacking)
5. Findall will show you whats happening better than match

Heres a 'hack-session'

from re import findall
>>> l = '    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\"Log Collection In Progress\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"' 


# Start simple
>>> findall(r'^\s',l)
[' ']
>>> findall(r'^\s*',l)
['    ']
>>> findall(r'^\s*"',l)
['    "']
>>> findall(r'^\s*"SHELF-',l)
['    "SHELF-']
>>> findall(r'^\s*"SHELF-.*',l)
['    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:"Log Collection In Progress",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"']
>>> findall('^\s*"SHELF-.*',l)
['    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:"Log Collection In Progress",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"']
>>> findall('^\s*"SHELF-.SC*',l)
[]
>>> findall('^\s*"SHELF-.*SC',l)
['    "SHELF-17:LOG_COLN_IP,SC']
>>> findall('^\s*"SHELF-.*?SC',l)
['    "SHELF-17:LOG_COLN_IP,SC']
>>> findall('^\s*"SHELF-.*?,SC',l)
['    "SHELF-17:LOG_COLN_IP,SC']
>>> findall('(^\s*)"SHELF-.*?,SC',l)
['    ']
>>> findall('\(^\s*\)"SHELF-.*?,SC',l)
[]
>>> findall('(^\s*)"SHELF-.*?,SC',l)
['    ']
>>> findall('(^\s*)("SHELF-.*?,SC)',l)
[('    ', '"SHELF-17:LOG_COLN_IP,SC')]


From rosuav at gmail.com  Thu Mar 27 00:41:31 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 27 Mar 2014 15:41:31 +1100
Subject: regex line by line over file
In-Reply-To: <a79bc9f2-eb49-4037-9e1a-eb234dca12d5@googlegroups.com>
References: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>
 <a79bc9f2-eb49-4037-9e1a-eb234dca12d5@googlegroups.com>
Message-ID: <CAPTjJmqt0jJHVDBqXPes1hmgAq2V5-f_QQ1T4kMyenQ9y1SvZQ@mail.gmail.com>

On Thu, Mar 27, 2014 at 3:14 PM, James Smith <bjlockie at lockie.ca> wrote:
> I tried the re.M in the compile and that didn't help.

Okay. Try printing out the repr of the line at the point where you
have the commented-out write to stdout. That might tell you if there's
some other difference. At that point, you'll know if the issue is with
reading it from the file.

Also, please either stop using Google Groups, or clean up its messes.
I don't like having to read through piles of double-spaced junk in the
quoted text. Thanks!

ChrisA


From rustompmody at gmail.com  Thu Mar 27 01:02:06 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Wed, 26 Mar 2014 22:02:06 -0700 (PDT)
Subject: Delayed evaluation of expressions
In-Reply-To: <871txok29s.fsf@elektro.pacujo.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8489.1395721791.18130.python-list@python.org>
 <feab8d4b-2f00-4f5f-ba57-2815439faecc@googlegroups.com>
 <CAPTjJmra0bs_6TP1iHmT5Auc1dykqeLUskg674z5OAB+jHv86g@mail.gmail.com>
 <53314FC1.2010603@rece.vub.ac.be>
 <CAPTjJmoOvEt-umUW38nW_7==3pciwGiZdJv2zFsNw5Kf_dW_Sw@mail.gmail.com>
 <mailman.8512.1395743920.18130.python-list@python.org>
 <5331652c$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8514.1395747979.18130.python-list@python.org>
 <f7eef30a-5e4a-45ae-8bdf-44e79e5c401f@googlegroups.com>
 <53319e60$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8550.1395791763.18130.python-list@python.org>
 <53321b7e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8562.1395808246.18130.python-list@python.org>
 <5332fae0$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <9ad6730a-f2d9-42fe-a822-88db2916972b@googlegroups.com>
 <mailman.8592.1395872698.18130.python-list@python.org>
 <871txok29s.fsf@elektro.pacujo.net>
Message-ID: <3dcf41ad-a036-4f51-af23-9672b7e71e40@googlegroups.com>

On Thursday, March 27, 2014 4:15:19 AM UTC+5:30, Marko Rauhamaa wrote:
> Chris Angelico :

> > You prove here that Python has first-class expressions in the same way
> > that 80x86 assembly language has garbage collection. Sure, you can
> > implement it using the primitives you have, but that's not support.

> I was more reminded of STL and Boost. For example:

>    std::for_each(v.begin(), v.end(),
>      ( 
>        switch_statement(
>          _1,
>          case_statement<0>(std::cout << constant("zero")),
>          case_statement<1>(std::cout << constant("one")),
>          default_statement(cout << constant("other: ") << _1)
>        ), 
>        cout << constant("\n") 
>      )
>    );

> (<URL: http://www.boost.org/doc/libs/1_55_0/doc/html/lambda/
> le_in_details.html#lambda.switch_statement>)

I must admit I have a hard time reading C++!

However that link seems to be saying more or less what I am -- viz. lambda
is a delay operator


From steve at pearwood.info  Thu Mar 27 01:32:03 2014
From: steve at pearwood.info (Steven D'Aprano)
Date: 27 Mar 2014 05:32:03 GMT
Subject: regex line by line over file
References: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>
Message-ID: <5333b7d2$0$2756$c3e8da3$76491128@news.astraweb.com>

On Wed, 26 Mar 2014 20:23:29 -0700, James Smith wrote:

> I can't get this to work.
> It runs but there is no output when I try it on a file.

Simplify, simplify, simplify. Either you will find the problem, or you 
will find the simplest example that demonstrates the problem.

In this case, the problem is that your regex is not matching what you 
expect it to match. So eliminate all the irrelevant cruft that is 
just noise, complicating the problem. Start with the simplest thing that
works and add complexity until the problem returns.

Eliminate the file. You can embed your data in a string, and try to match 
the regex against the string. Eliminate all the old commented-out code, 
that's just irrelevant. Eliminate reading from sys.argv, that has nothing 
to do with the problem.

So we get down to this:

import re
pat = re.compile('^\s*\"SHELF-.*,SC,.*,:\\\"Log Collection In Progress\\\"')
line1 = '    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\"Log Collection In Progress\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"'
print(pat.match(line1))

which matches.

Now let's get rid of those leaning toothpicks. We can use print
to see the repr() of the pattern, and a raw string to clean it up.
At the interactive interpreter:


py> print(pat.pattern)
^\s*"SHELF-.*,SC,.*,:\"Log Collection In Progress\"


Similarly for line1. I'll also use implicit concatenation to split 
it over multiple source lines. Raw strings, r'' or r"", don't need 
to escape the backslashes. Implicit concatenation means that two 
strings with no operator between them is implicitly concatenated 
into a single string:

    'abc' "def"

becomes 'abcdef'. By putting the pieces inside parentheses, I can 
put each piece on a separate line, which makes it easier to read 
compared to one giant long line.

pat = re.compile(
        r'^\s*"SHELF-.*,SC,.*,:\"Log Collection In Progress\"'
        )

line1 = (
        '    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:"'
        'Log Collection In Progress",NONE:1700000035-6364-1048,:'
        'YEAR=2014,MODE=NONE"'
        )


And at the interactive interpreter, I get a match:

py> pat.match(line1)
<_sre.SRE_Match object at 0xb721ad78>


So now we move on to the content of the one-line file. I don't have
access to the file, so all I have to go by is what you state it 
contains:

[quote]
The test file just has one line:
    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\"Log Collection In Progress\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"
[end quote]

which I interpret like this:

line2 = '    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\"Log Collection In Progress\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"\n'


(note the newline at the end), or if you prefer:

line2 = (
        '    "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:"'
        'Log Collection In Progress",NONE:1700000035-6364-1048,:'
        'YEAR=2014,MODE=NONE"\n'
        )


Except for the newline, it equals line1, and it also matches the 
pattern:

py> pat.match(line2)
<_sre.SRE_Match object at 0xb721ab48>


So now we know that the regex matches the data you think you have.
The next questions are:

- are you reading the right file?
- are you mistaken about the content of the file?

I can't help you with the first. But the second: try running this:

# line2 and pat as defined above
filename = sys.argv[1]
with open(filename) as f:
    for line in f:
        print(len(line), line==line2, repr(line))
        print(repr(pat.match(line)))


which will show you what you have and whether or not it matches 
what you think it has. I expect that the file contents is not what 
you think it is, because the regex is matching the sample line.

Good luck!



-- 
Steven


From ian.g.kelly at gmail.com  Thu Mar 27 03:32:36 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 27 Mar 2014 01:32:36 -0600
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <53318664$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
 <mailman.8511.1395743071.18130.python-list@python.org>
 <roy-333172.08211925032014@news.panix.com>
 <53318664$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALwzid=iq7j37QtMveOKDSC7NgNz8MBFBpEnmt35JjshPJEdTQ@mail.gmail.com>

On Tue, Mar 25, 2014 at 7:36 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Yes, Python could have changed the meaning of {} to mean the empty set.
> But you know what? The empty set is not that important. Sets are not
> fundamental to Python. Python didn't even have sets until 2.3, and at
> first they were just a standard library module, not even built-in. Dicts,
> on the other hand, are fundamental to Python. They are used everywhere.
> Python is, in a very real sense, built on dicts, not sets. You can
> implement sets starting from dicts, but not the other way around: dicts
> are more fundamental than sets.

Challenge accepted!

The _lookup method in the following is based on a recipe from Raymond Hettinger.


from collections.abc import MutableMapping


class SetBasedDict(MutableMapping):

    def __init__(self, initial, **kwargs):
        self._contents = set()
        self.update(initial, **kwargs)

    def clear(self):
        self._contents.clear()

    def __iter__(self):
        for item in self._contents:
            yield item.key

    def __len__(self):
        return len(self._contents)

    def __getitem__(self, key):
        item = self._lookup(key)
        if item is None:
            raise KeyError(key)
        return item.value

    def __setitem__(self, key, value):
        item = self._lookup(key)
        if item is not None:
            item.value = value
        else:
            item = _DictItem(key, value)
            self._contents.add(item)

    def __delitem__(self, key):
        self._contents.remove(_DictItem(key, None))

    def _lookup(self, key):
        p = _DictSearchProxy(key)
        if p in self._contents:
            return p.match
        return None


class _DictItem:

    def __init__(self, key, value):
        self.key = key
        self.value = value

    def __hash__(self):
        return hash(self.key)

    def __eq__(self, other):
        if not isinstance(other, _DictItem):
            return NotImplemented
        return self.key == other.key


class _DictSearchProxy:

    def __init__(self, obj):
        self.obj = obj
        self.match = obj

    def __eq__(self, other):
        if not isinstance(other, _DictItem):
            return NotImplemented
        result = (self.obj == other.key)
        if result:
            self.match = other
        return result

    def __hash__(self):
        return hash(self.obj)


From ian.g.kelly at gmail.com  Thu Mar 27 03:43:41 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 27 Mar 2014 01:43:41 -0600
Subject: Time we switched to unicode? (was Explanation of this Python
 language feature?)
In-Reply-To: <CALwzid=iq7j37QtMveOKDSC7NgNz8MBFBpEnmt35JjshPJEdTQ@mail.gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <mailman.8472.1395705541.18130.python-list@python.org>
 <0b78649a-16b3-4410-8258-e859578d62be@googlegroups.com>
 <mailman.8483.1395717465.18130.python-list@python.org>
 <53060a97-44fb-4e53-a7a7-d5eeed416f62@googlegroups.com>
 <CAPTjJmr=S_sxd-AB705ma0C29ir_BsyVpnsTqsKNRCgDqDyK-A@mail.gmail.com>
 <mailman.8511.1395743071.18130.python-list@python.org>
 <roy-333172.08211925032014@news.panix.com>
 <53318664$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CALwzid=iq7j37QtMveOKDSC7NgNz8MBFBpEnmt35JjshPJEdTQ@mail.gmail.com>
Message-ID: <CALwzid=Pw0tojDO5JZdQgQZNw0_SXph5EE0f5NAkFHFQnU_-Ow@mail.gmail.com>

On Thu, Mar 27, 2014 at 1:32 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Tue, Mar 25, 2014 at 7:36 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> Yes, Python could have changed the meaning of {} to mean the empty set.
>> But you know what? The empty set is not that important. Sets are not
>> fundamental to Python. Python didn't even have sets until 2.3, and at
>> first they were just a standard library module, not even built-in. Dicts,
>> on the other hand, are fundamental to Python. They are used everywhere.
>> Python is, in a very real sense, built on dicts, not sets. You can
>> implement sets starting from dicts, but not the other way around: dicts
>> are more fundamental than sets.
>
> Challenge accepted!

Oops, I forgot to allow for a 0-argument constructor.  Please revise
the SetBasedDict.__init__ method to:

    def __init__(self, initial=(), **kwargs):
        self._contents = set()
        if initial or kwargs:
            self.update(initial, **kwargs)


From breamoreboy at yahoo.co.uk  Thu Mar 27 04:40:25 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 27 Mar 2014 08:40:25 +0000
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <roy-34E0D7.21383226032014@news.panix.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8597.1395883727.18130.python-list@python.org>
 <roy-34E0D7.21383226032014@news.panix.com>
Message-ID: <lh0o5l$o8i$1@ger.gmane.org>

On 27/03/2014 01:38, Roy Smith wrote:
> In article <mailman.8597.1395883727.18130.python-list at python.org>,
>   Chris Angelico <rosuav at gmail.com> wrote:
>
>> On Thu, Mar 27, 2014 at 11:16 AM, Steven D'Aprano
>> <steve+comp.lang.python at pearwood.info> wrote:
>>> If an event happened 30 hours ago, it is correct to say that it occurred
>>> "18 hours after 2 days ago", but who talks that way?
>>
>> That response demonstrates real genius. Rue the datetime? Who talks like that?
>
> "I had a dangling pointer error, and blew my stack to half past last
> wednesday"
>

IIRC the Germans (possibly amongst others) would say that as half to 
last thursday, or is that thurstag? :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From antoon.pardon at rece.vub.ac.be  Thu Mar 27 05:36:02 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 27 Mar 2014 10:36:02 +0100
Subject: unicode as valid naming symbols
In-Reply-To: <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com> <53329549.1000208@rece.vub.ac.be>
 <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>
Message-ID: <5333F102.1030309@rece.vub.ac.be>

On 26-03-14 17:37, Ian Kelly wrote:
> On Wed, Mar 26, 2014 at 2:52 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> Of course we don't have to follow mathematical convention with python. However allowing any
>> unicode symbol as an identifier doesn't prohibit from using ? as an operator. We do have
>> "in" and "is" as operators now, even if they would otherwise be acceptable identifiers.
>> So I wonder, would you consider to introduce log as an operator. 2 log x seems an interesting
>> operation for a programmer.
> If it's going to become an operator, then it has to be a keyword.
> Changing a token that is currently allowed to be an identifier into a
> keyword is generally avoided as much as possible, because it breaks
> backward compatibility.  "in" and "is" have both been keywords for a
> very long time, perhaps since the initial release of Python.

I know, for such a reason I would love it if keywords would have been
written like this: ??? (using mathematical bold) instead of just like
this: def (using plain latin letters). It would mean among other things
we could just write operator.not instead of having to write operator.not_

-- 
Antoon Pardon



From michael at stroeder.com  Mon Mar 24 06:26:14 2014
From: michael at stroeder.com (=?ISO-8859-1?Q?Michael_Str=F6der?=)
Date: Mon, 24 Mar 2014 11:26:14 +0100
Subject: ANN: python-ldap 2.4.15
Message-ID: <mailman.8610.1395913871.18130.python-announce-list@python.org>

Find a new release of python-ldap:

  http://pypi.python.org/pypi/python-ldap/2.4.15

python-ldap provides an object-oriented API to access LDAP directory
servers from Python programs. It mainly wraps the OpenLDAP 2.x libs for
that purpose. Additionally it contains modules for other LDAP-related
stuff (e.g. processing LDIF, LDAP URLs and LDAPv3 schema).

Project's web site:

  http://www.python-ldap.org/

Ciao, Michael.

----------------------------------------------------------------
Released 2.4.15 2014-03-24

Changes since 2.4.14:

Lib/
* Added missing modules ldap.controls.openldap and
  ldap.controls.pwdpolicy to setup.py
* Added missing imports to ldap.controls.pwdpolicy
* Fixed ldap.controls.pwdpolicy.decodeControlValue() to decode
  string of digits
* Support for X-SUBST in schema element class LDAPSyntax
* Support for X-ORDERED and X-ORIGIN in schema element class AttributeType
* ldapurl: New scope 'subordinates' defined in
  draft-sermersheim-ldap-subordinate-scope

Modules/
* New constant ldap.SCOPE_SUBORDINATE derived from ldap.h for
  draft-sermersheim-ldap-subordinate-scope
* Fixed constant ldap.sasl.CB_GETREALM (thanks to Martin Pfeifer)



From dfnsonfsduifb at gmx.de  Thu Mar 27 06:09:13 2014
From: dfnsonfsduifb at gmx.de (Johannes Bauer)
Date: Thu, 27 Mar 2014 11:09:13 +0100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <mailman.8587.1395868967.18130.python-list@python.org>
References: <mailman.8587.1395868967.18130.python-list@python.org>
Message-ID: <lh0tc6$bih$1@news.albasani.net>

On 26.03.2014 10:53, Jean-Michel Pichavant wrote:

> Note : I don't see what's wrong in your example, however I have the feeling the term "stupiditie" is a little bit strong ;)

The problem is that for a given timedelta t with t > 0 it is intuitive
to think that its string representation str(t) would follow the rule

"-" + str(t) == str(-t)

But it doesn't.

> -- IMPORTANT NOTICE: 
> 
> The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

I hereby inform you that I - probably by accident received your very
confidential and privileged message! All hardware has already been
thrown into the incinerator, is that good enough for you? Or do I have
to fulfill some ISO-9001 certified privileged mail destruction
procedure? Please advise on how I shall continue my life.

Cheers,
Johannes

IMPORTANT NOTICE:

If you write mails to newsgroups with a ridiculous confidentiality
footer, you are obliged under section 14.9a of the Imbecile Act to take
a blunt object of no less than 12 kg weight and hit yourself repeatedly
in the head until the email footer disappears. Failure to comply might
lead to criminal prosecution and/or permanent constipation! Thank you.


-- 
>> Wo hattest Du das Beben nochmal GENAU vorhergesagt?
> Zumindest nicht ?ffentlich!
Ah, der neueste und bis heute genialste Streich unsere gro?en
Kosmologen: Die Geheim-Vorhersage.
 - Karl Kaos ?ber R?diger Thomas in dsa <hidbv3$om2$1 at speranza.aioe.org>


From dfnsonfsduifb at gmx.de  Thu Mar 27 06:22:27 2014
From: dfnsonfsduifb at gmx.de (Johannes Bauer)
Date: Thu, 27 Mar 2014 11:22:27 +0100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <roy-142548.20582725032014@news.panix.com>	<mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh0u51$dj8$1@news.albasani.net>

On 27.03.2014 01:16, Steven D'Aprano wrote:

> py> divmod(30, 24)
> (1, 6)
> 
> That makes perfect intuitive sense: 30 hours is 1 day with 6 hours 
> remaining. In human-speak, we'll say that regardless of whether the 
> timedelta is positive or negative: we'll say "1 day and 6 hours from now" 
> or "1 day and 6 hours ago". But when we specify the sign:
> 
> py> divmod(-30, 24)
> (-2, 18)
> 
> If an event happened 30 hours ago, it is correct to say that it occurred 
> "18 hours after 2 days ago", but who talks that way?

Well, no matter how timedeltas internal representation is and if they
use modular division or (they probably do, I agree) this shouldn't
affect the display at all. Internally they can use any arbitrary
representation, but for the external representation I think a very sane
requirement should be that for a given timedelta t with t > 0 it is its
string representation str(t) would satisfy:

"-" + str(t) == str(-t)

Besides, there's an infinite amount of (braindead) timedelta string
representations. For your -30 hours, it is perfectly legal to say

123 days, -2982 hours

Yet Python doesn't (but chooses an equally braindead representation).

Where can I enter a PIP that proposes that all timedelta strings are
fixed at 123 days (for positive, non-prime amount of seconds) and fixed
at -234 days (for all negative or positive prime amount of seconds)?

Cheers,
Johannes

-- 
>> Wo hattest Du das Beben nochmal GENAU vorhergesagt?
> Zumindest nicht ?ffentlich!
Ah, der neueste und bis heute genialste Streich unsere gro?en
Kosmologen: Die Geheim-Vorhersage.
 - Karl Kaos ?ber R?diger Thomas in dsa <hidbv3$om2$1 at speranza.aioe.org>


From rosuav at gmail.com  Thu Mar 27 06:44:09 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 27 Mar 2014 21:44:09 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <lh0u51$dj8$1@news.albasani.net>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
Message-ID: <CAPTjJmrAcKTFeJ-dAZpxO_s=iGQGadAt+Op++tKt4eg0xQUJrQ@mail.gmail.com>

On Thu, Mar 27, 2014 at 9:22 PM, Johannes Bauer <dfnsonfsduifb at gmx.de> wrote:
> Besides, there's an infinite amount of (braindead) timedelta string
> representations. For your -30 hours, it is perfectly legal to say
>
> 123 days, -2982 hours
>
> Yet Python doesn't (but chooses an equally braindead representation).

It's not "equally braindead", it follows a simple and logical rule:
Only the day portion is negative. That might not be perfectly suited
to all situations, but it does mean that adding and subtracting whole
days will never change the representation of the time. That's a
reasonable promise. What you propose is completely arbitrary, and yes
it WOULD be braindead to have str() return that (although of course
this should be accepted as input).

> Where can I enter a PIP that proposes that all timedelta strings are
> fixed at 123 days (for positive, non-prime amount of seconds) and fixed
> at -234 days (for all negative or positive prime amount of seconds)?
>

Doesn't need a PEP. Just subclass it or monkey-patch it and use it as
you will. :)

ChrisA


From dfnsonfsduifb at gmx.de  Thu Mar 27 07:05:09 2014
From: dfnsonfsduifb at gmx.de (Johannes Bauer)
Date: Thu, 27 Mar 2014 12:05:09 +0100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <mailman.8613.1395917059.18130.python-list@python.org>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
Message-ID: <lh10l2$iak$1@news.albasani.net>

On 27.03.2014 11:44, Chris Angelico wrote:
> On Thu, Mar 27, 2014 at 9:22 PM, Johannes Bauer <dfnsonfsduifb at gmx.de> wrote:
>> Besides, there's an infinite amount of (braindead) timedelta string
>> representations. For your -30 hours, it is perfectly legal to say
>>
>> 123 days, -2982 hours
>>
>> Yet Python doesn't (but chooses an equally braindead representation).
> 
> It's not "equally braindead", it follows a simple and logical rule:
> Only the day portion is negative. That might not be perfectly suited
> to all situations, but it does mean that adding and subtracting whole
> days will never change the representation of the time. That's a
> reasonable promise.

Why would the stability of the *string* output of the time
representation be of any interest whatsoever? Do you have any even
halfways reasonable usecase for that?

> What you propose is completely arbitrary, 

No. What I propose is that for t > 0 this holds:

"-" + str(t) == str(-t)

Which is far from arbitrary. It follows "natural" rules of inverting
something (-abs(x) == -x), and it yields a (truly) human-readable form
of showing a timedelta.

Please don't mix this up with the very apparent braindead proposal of
mine. In case you didn't notice, this was irony at work. The word
"braindead" I chose to describe the format should have tipped you off to
that.

>> Where can I enter a PIP that proposes that all timedelta strings are
>> fixed at 123 days (for positive, non-prime amount of seconds) and fixed
>> at -234 days (for all negative or positive prime amount of seconds)?
> 
> Doesn't need a PEP. Just subclass it or monkey-patch it and use it as
> you will. :)

Nonono, you misunderstand: I want everyone to suffer under the braindead
representation, just as it is now!

Cheers,
Johannes

-- 
>> Wo hattest Du das Beben nochmal GENAU vorhergesagt?
> Zumindest nicht ?ffentlich!
Ah, der neueste und bis heute genialste Streich unsere gro?en
Kosmologen: Die Geheim-Vorhersage.
 - Karl Kaos ?ber R?diger Thomas in dsa <hidbv3$om2$1 at speranza.aioe.org>


From dfnsonfsduifb at gmx.de  Thu Mar 27 07:25:56 2014
From: dfnsonfsduifb at gmx.de (Johannes Bauer)
Date: Thu, 27 Mar 2014 12:25:56 +0100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <mailman.8613.1395917059.18130.python-list@python.org>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
Message-ID: <lh11s1$kj3$1@news.albasani.net>

On 27.03.2014 11:44, Chris Angelico wrote:

> It's not "equally braindead", it follows a simple and logical rule:
> Only the day portion is negative.

The more I think about it, the sillier this rule seems to me.

A timedelta is a *whole* object. Either the whole delta is negative or
it is not. It doesn't make sense to split it up in two parts and
arbitrarily define one to be always nonnegative and the other to have no
restrictions.

The only locical reasoning behind this could be to argue that "-2 days"
makes more sense than "-15 minutes". Which it doesn't.

Worse: Negating a timedelta (which I would argue is a fairly common
operation) makes the whole thing unstable representation-wise:

>>> str(datetime.timedelta(2, 30))
'2 days, 0:00:30'
>>> str(-datetime.timedelta(2, 30))
'-3 days, 23:59:30'

And it makes it extremely error-prone to the reader:

>>> str(datetime.timedelta(0, -1))
'-1 day, 23:59:59'

This looks MUCH more like "almost two days ago" than

'-00:00:01'

does.

In any case, the str() function is *only* about the representation that
can be read by humans. Therefore its highest priority should be to
output something that can, in fact, be easily parsed by humans. The
current format is nothing of the sort.

Cheers,
Johannes

-- 
>> Wo hattest Du das Beben nochmal GENAU vorhergesagt?
> Zumindest nicht ?ffentlich!
Ah, der neueste und bis heute genialste Streich unsere gro?en
Kosmologen: Die Geheim-Vorhersage.
 - Karl Kaos ?ber R?diger Thomas in dsa <hidbv3$om2$1 at speranza.aioe.org>


From rosuav at gmail.com  Thu Mar 27 07:33:55 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 27 Mar 2014 22:33:55 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <lh10l2$iak$1@news.albasani.net>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh10l2$iak$1@news.albasani.net>
Message-ID: <CAPTjJmrZRHORpwcA9iRoxJY0-W_B7wp3ZKzT6pY=35M40SeP0Q@mail.gmail.com>

On Thu, Mar 27, 2014 at 10:05 PM, Johannes Bauer <dfnsonfsduifb at gmx.de> wrote:
> On 27.03.2014 11:44, Chris Angelico wrote:
>> On Thu, Mar 27, 2014 at 9:22 PM, Johannes Bauer <dfnsonfsduifb at gmx.de> wrote:
>>> Besides, there's an infinite amount of (braindead) timedelta string
>>> representations. For your -30 hours, it is perfectly legal to say
>>>
>>> 123 days, -2982 hours
>>>
>>> Yet Python doesn't (but chooses an equally braindead representation).
>>
>> It's not "equally braindead", it follows a simple and logical rule:
>> Only the day portion is negative. That might not be perfectly suited
>> to all situations, but it does mean that adding and subtracting whole
>> days will never change the representation of the time. That's a
>> reasonable promise.
>
> Why would the stability of the *string* output of the time
> representation be of any interest whatsoever? Do you have any even
> halfways reasonable usecase for that?
>
>> What you propose is completely arbitrary,
>
> No. What I propose is that for t > 0 this holds:
>
> "-" + str(t) == str(-t)
>
> Which is far from arbitrary.

When you said "equally braindead", I took that as indicating that the
current representation is as braindead as "123 days, -2982 hours". My
point is that it's not as arbitrary as that. Your "real proposal", if
you like, is arguably better; but I'm just saying that the current one
isn't arbitrary.

> It follows "natural" rules of inverting
> something (-abs(x) == -x), and it yields a (truly) human-readable form
> of showing a timedelta.
>
> Please don't mix this up with the very apparent braindead proposal of
> mine. In case you didn't notice, this was irony at work. The word
> "braindead" I chose to describe the format should have tipped you off to
> that.

Yes, I knew that that was irony. I was taking argument with your
declaration that the current form is just as bad. Taking it to a
different type: The repr() of a string tries to be short, where
possible, by using either single or double quotes, but won't use a raw
representation, nor triple-quoted:

>>> ' \' '
" ' "
>>> " \" "
' " '
>>> ' \"\'\"\'\"\'\"\' '
' "\'"\'"\'"\' '
>>> " \"\'\"\'\"\'\"\' "
' "\'"\'"\'"\' '
>>> ''' "'"'"'"' '''
' "\'"\'"\'"\' '
>>> r' \\\\\\\\\\\\\\ '
' \\\\\\\\\\\\\\\\\\\\\\\\\\\\ '

You could argue that representing a string as raw or triple-quoted
would be "more correct", and yet the current repr is not arbitrary.
The current form is not actively bad, even if it would be possible to
find something better.

>>> Where can I enter a PIP that proposes that all timedelta strings are
>>> fixed at 123 days (for positive, non-prime amount of seconds) and fixed
>>> at -234 days (for all negative or positive prime amount of seconds)?
>>
>> Doesn't need a PEP. Just subclass it or monkey-patch it and use it as
>> you will. :)
>
> Nonono, you misunderstand: I want everyone to suffer under the braindead
> representation, just as it is now!

Oh, absolutely! In that case, just slip a patch into the next point
release; people won't mind that changing in 3.4.1!

ChrisA


From rosuav at gmail.com  Thu Mar 27 07:42:26 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 27 Mar 2014 22:42:26 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <lh11s1$kj3$1@news.albasani.net>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
Message-ID: <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>

On Thu, Mar 27, 2014 at 10:25 PM, Johannes Bauer <dfnsonfsduifb at gmx.de> wrote:
> And it makes it extremely error-prone to the reader:
>
>>>> str(datetime.timedelta(0, -1))
> '-1 day, 23:59:59'
>
> This looks MUCH more like "almost two days ago" than
>
> '-00:00:01'
>
> does.

It's easy when the timedelta is >-1 day. Is it as clear when it's
further negative?

In any case... what I'd suggest would be opening a tracker issue, or
discussing this on python-ideas, and seeing what core devs think of
the matter. I think that, on balance, it's probably better to show the
whole thing with the same sign; but should it be:

>>> str(datetime.timedelta(-1, -1))
'-1 day, 00:00:01'

or should the hyphen be repeated:

>>> str(datetime.timedelta(-1, -1))
'-1 day, -00:00:01'

? How does it read in a larger expression? All this bikeshedding, and
more, available gratis on python-ideas. :)

ChrisA


From skip at pobox.com  Thu Mar 27 07:56:34 2014
From: skip at pobox.com (Skip Montanaro)
Date: Thu, 27 Mar 2014 06:56:34 -0500
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
 <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
Message-ID: <CANc-5Uys3UgP8s84JiNRkw4t+ecrrLVVtdbwwyuwmt7W9Qg_GQ@mail.gmail.com>

I took a moment to scan the datetime documentation. The behavior of
str() on timedelta objects is very consistent, and matches the
internal representation. From the docs:

str(t) Returns a string in the form [D day[s], ][H]H:MM:SS[.UUUUUU],
where D is negative for negative t. (5)

Note (5) reads: String representations of timedelta objects are
normalized similarly to their internal representation. This leads to
somewhat unusual results for negative timedeltas.

Feel free to submit a patch to improve str(t), where t is negative,
though as Chris suggested, hashing this out on python-ideas would be a
good idea. I suggest you start with some concrete examples. There are,
as I see it, two common cases where t is negative:

  -1 day < t < 0

and

  t <= -1 day

Skip


From rosuav at gmail.com  Thu Mar 27 08:20:30 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 27 Mar 2014 23:20:30 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <CANc-5Uys3UgP8s84JiNRkw4t+ecrrLVVtdbwwyuwmt7W9Qg_GQ@mail.gmail.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
 <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
 <CANc-5Uys3UgP8s84JiNRkw4t+ecrrLVVtdbwwyuwmt7W9Qg_GQ@mail.gmail.com>
Message-ID: <CAPTjJmq95oFsPKO_nD8Dx_oniHaAkMV=QnHK7TiJxr8=s04yfA@mail.gmail.com>

On Thu, Mar 27, 2014 at 10:56 PM, Skip Montanaro <skip at pobox.com> wrote:
> There are,
> as I see it, two common cases where t is negative:
>
>   -1 day < t < 0
>
> and
>
>   t <= -1 day

There are two types of negative numbers: Those closer to zero than -1,
and those not closer to zero than -1. Yeah, I think those are the most
common cases. :)

ChrisA


From roy at panix.com  Thu Mar 27 08:52:24 2014
From: roy at panix.com (Roy Smith)
Date: Thu, 27 Mar 2014 08:52:24 -0400
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
Message-ID: <roy-E22E44.08522427032014@news.panix.com>

> On Thu, Mar 27, 2014 at 9:22 PM, Johannes Bauer <dfnsonfsduifb at gmx.de> wrote:
> > Besides, there's an infinite amount of (braindead) timedelta string
> > representations. For your -30 hours, it is perfectly legal to say
> >
> > 123 days, -2982 hours
> >
> > Yet Python doesn't (but chooses an equally braindead representation).


In article <mailman.8613.1395917059.18130.python-list at python.org>,
 Chris Angelico <rosuav at gmail.com> wrote:
> It's not "equally braindead", it follows a simple and logical rule:
> Only the day portion is negative.

Simple and logical, yes.  But also entirely braindead.

> That might not be perfectly suited to all situations

Give ma a real-life situation where you would want such behavior.

> What you propose is completely arbitrary, and yes
> it WOULD be braindead to have str() return that

Chris, I believe you need to have your sarcasm detection circuitry 
recalibrated :-)


From skip at pobox.com  Thu Mar 27 09:01:39 2014
From: skip at pobox.com (Skip Montanaro)
Date: Thu, 27 Mar 2014 08:01:39 -0500
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <CAPTjJmq95oFsPKO_nD8Dx_oniHaAkMV=QnHK7TiJxr8=s04yfA@mail.gmail.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
 <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
 <CANc-5Uys3UgP8s84JiNRkw4t+ecrrLVVtdbwwyuwmt7W9Qg_GQ@mail.gmail.com>
 <CAPTjJmq95oFsPKO_nD8Dx_oniHaAkMV=QnHK7TiJxr8=s04yfA@mail.gmail.com>
Message-ID: <CANc-5UxM_Fs+dsEEKBxrx7tdsVumJquRi6R1GooX_rFayWpk4g@mail.gmail.com>

>> There are,
>> as I see it, two common cases where t is negative:
>>
>>   -1 day < t < 0
>>
>> and
>>
>>   t <= -1 day
>
> There are two types of negative numbers: Those closer to zero than -1,
> and those not closer to zero than -1. Yeah, I think those are the most
> common cases. :)

Sorry I wasn't clear. I see two cases w.r.t. *display*, those where
you need to display the number of days back (possibly accounting for
even larger time intervals to make it more human readable), those
where you don't.  Yes, as you observed, they completely cover the
negative timedelta space with two non-overlapping intervals.

Roy's original rant was about how a negative timedelta was
stringified, when what he seemed to care about was mostly the time
interval between now and the previous sunset (which will be less than
a day, unless your day length is advancing -- between the winter and
summer solstices -- and you compute that interval a few seconds before
sunset). The common "how long ago was sunset?" (|delta| < 1 day) case
is handled just fine by my little negate-the-timedelta hack, e.g.:

>>> "-%s" % (-datetime.timedelta(hours=-17, minutes=-12, seconds=-25.234))
'-17:12:25.234000'

Negative timedeltas with a magnitude of one day or more require
something else, perhaps like the ISO8601 duration stuff (which I
personally find distasteful, but that might be the best you can do in
the absence of an anchor datetime).

Skip


From bjlockie at lockie.ca  Thu Mar 27 09:41:55 2014
From: bjlockie at lockie.ca (James Smith)
Date: Thu, 27 Mar 2014 06:41:55 -0700 (PDT)
Subject: regex line by line over file
In-Reply-To: <5333b7d2$0$2756$c3e8da3$76491128@news.astraweb.com>
References: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>
 <5333b7d2$0$2756$c3e8da3$76491128@news.astraweb.com>
Message-ID: <87d43f6b-8b16-4b20-8ab0-d665acac9da6@googlegroups.com>

On Thursday, March 27, 2014 1:32:03 AM UTC-4, Steven D'Aprano wrote:

> - are you mistaken about the content of the file?
> 
> I can't help you with the first. But the second: try running this:
> 
> # line2 and pat as defined above
> filename = sys.argv[1]
> with open(filename) as f:
>     for line in f:
>         print(len(line), line==line2, repr(line))
>         print(repr(pat.match(line)))
> 
> which will show you what you have and whether or not it matches 
> what you think it has. I expect that the file contents is not what 
> you think it is, because the regex is matching the sample line.
> 
> Good luck!
> 
> -- 
> 
> Steven

It should match this:
(134, False, '\'   "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\\\\"Log Collection In Progress\\\\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"\\r\\n\'')

Is the \r\n on the end of the line screwing it up?


From marko at pacujo.net  Thu Mar 27 10:04:04 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 27 Mar 2014 16:04:04 +0200
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
 <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
 <mailman.8616.1395921402.18130.python-list@python.org>
Message-ID: <87txajwxez.fsf@elektro.pacujo.net>

Skip Montanaro <skip at pobox.com>:

> Feel free to submit a patch to improve str(t), where t is negative,

The cat's out of the bag already, isn't it?


Marko


From antoon.pardon at rece.vub.ac.be  Thu Mar 27 10:12:31 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 27 Mar 2014 15:12:31 +0100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <roy-E22E44.08522427032014@news.panix.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
Message-ID: <533431CF.6020102@rece.vub.ac.be>

On 27-03-14 13:52, Roy Smith wrote:
>> On Thu, Mar 27, 2014 at 9:22 PM, Johannes Bauer <dfnsonfsduifb at gmx.de> wrote:
>>> Besides, there's an infinite amount of (braindead) timedelta string
>>> representations. For your -30 hours, it is perfectly legal to say
>>>
>>> 123 days, -2982 hours
>>>
>>> Yet Python doesn't (but chooses an equally braindead representation).
>
> In article <mailman.8613.1395917059.18130.python-list at python.org>,
>  Chris Angelico <rosuav at gmail.com> wrote:
>> It's not "equally braindead", it follows a simple and logical rule:
>> Only the day portion is negative.
> Simple and logical, yes.  But also entirely braindead.

That you don't have a use for it and don't like it doesn't
make it brain dead.
 

>> That might not be perfectly suited to all situations
> Give ma a real-life situation where you would want such behavior.

What good would that do? The fact that someone else could
give a real-life situation where they wanted that, wouldn't
mean that you would recognize it as a situation where you
wanted it, and so you could still call it brain dead.

I don't recall specifics, but I do remember multiple times
where I was working with a structure that consisted of
a whole part and a fracture part where I found it useful
to have the fracture part always positive and displayed
as such.

Your background is obviously different and you don't like it.
Fine, that doesn't make it brain dead.

-- 
Antoon Pardon



From rosuav at gmail.com  Thu Mar 27 10:15:19 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 01:15:19 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <533431CF.6020102@rece.vub.ac.be>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <533431CF.6020102@rece.vub.ac.be>
Message-ID: <CAPTjJmrOqVqs7p+swUKpd2CYS3ycdmoSwsuirKrTt+hJiyfLeg@mail.gmail.com>

On Fri, Mar 28, 2014 at 1:12 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> I don't recall specifics, but I do remember multiple times
> where I was working with a structure that consisted of
> a whole part and a fracture part where I found it useful
> to have the fracture part always positive and displayed
> as such.

One has already been shared in this thread: Logarithms, where the part
before the decimal is the scale and the part after the decimal is the
mantissa. Makes very good sense to negate the first without changing
the second.

ChrisA


From rustompmody at gmail.com  Thu Mar 27 11:10:08 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 27 Mar 2014 08:10:08 -0700 (PDT)
Subject: unicode as valid naming symbols
In-Reply-To: <mailman.8607.1395912965.18130.python-list@python.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com> <53329549.1000208@rece.vub.ac.be>
 <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>
 <mailman.8607.1395912965.18130.python-list@python.org>
Message-ID: <bbe6f1ef-f6e6-4e3d-9dc3-8b3b66edaf40@googlegroups.com>

On Thursday, March 27, 2014 3:06:02 PM UTC+5:30, Antoon Pardon wrote:
> On 26-03-14 17:37, Ian Kelly wrote:
> > On Wed, Mar 26, 2014 at 2:52 AM, Antoon Pardon
> >> Of course we don't have to follow mathematical convention with python. However allowing any
> >> unicode symbol as an identifier doesn't prohibit from using ? as an operator. We do have
> >> "in" and "is" as operators now, even if they would otherwise be acceptable identifiers.
> >> So I wonder, would you consider to introduce log as an operator. 2 log x seems an interesting
> >> operation for a programmer.
> > If it's going to become an operator, then it has to be a keyword.
> > Changing a token that is currently allowed to be an identifier into a
> > keyword is generally avoided as much as possible, because it breaks
> > backward compatibility.  "in" and "is" have both been keywords for a
> > very long time, perhaps since the initial release of Python.

> I know, for such a reason I would love it if keywords would have been
> written like this: ??? (using mathematical bold) instead of just like
> this: def (using plain latin letters). It would mean among other things
> we could just write operator.not instead of having to write operator.not_

Just out of curiosity how do/did you type that?
When I see an exotic denizen from the unicode-universe I paste it into
emacs and ask "Who are you?"

But with your 'def' my emacs is going a bit crazy!


From python.list at tim.thechases.com  Thu Mar 27 11:34:04 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Thu, 27 Mar 2014 10:34:04 -0500
Subject: unicode as valid naming symbols
In-Reply-To: <bbe6f1ef-f6e6-4e3d-9dc3-8b3b66edaf40@googlegroups.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com>
 <53329549.1000208@rece.vub.ac.be>
 <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>
 <mailman.8607.1395912965.18130.python-list@python.org>
 <bbe6f1ef-f6e6-4e3d-9dc3-8b3b66edaf40@googlegroups.com>
Message-ID: <20140327103404.3fd45743@bigbox.christie.dr>

On 2014-03-27 08:10, Rustom Mody wrote:
> > I know, for such a reason I would love it if keywords would have
> > been written like this: ??? (using mathematical bold) instead of
> > just like this: def (using plain latin letters). It would mean
> > among other things we could just write operator.not instead of
> > having to write operator.not_
> 
> Just out of curiosity how do/did you type that?
> When I see an exotic denizen from the unicode-universe I paste it
> into emacs and ask "Who are you?"
> 
> But with your 'def' my emacs is going a bit crazy!

I have the following in a file, which I can then open with Vim.  I
just type the text I want above the corresponding row of capital
letters and execute the statement on the first line.  Vim then
populates the system clipboard with the corresponding letters in the
Unicode font.  I'm sure there are font-translator pages that would
make it a little easier, but I'd already done this.  Just adjust for
Emacs ;-)

-tkc


let @+=join(map(split(getline('.'), '\zs'),
'matchstr(getline(line(".")+((v:val >= "A" && v:val <= "Z")?1:2)),
".\\{".(char2nr(tolower(v:val))-char2nr("a"))."}\\zs.")'),'')
ABCDEFGHIJKLMNOPQRSTUVWXYZ ASCII upper
abcdefghijklmnopqrstuvwxyz ASCII lower
?????????????????????????? bold serif upper
?????????????????????????? bold serif lower
?????????????????????????? italic serif upper
?????????????????????????? italic serif lower
?????????????????????????? bold italic serif upper
?????????????????????????? bold italic serif lower
?????????????????????????? script upper
?????????????????????????? script lower
?????????????????????????? fraktur upper
?????????????????????????? fraktur lower
?????????????????????????? fraktur bold upper
?????????????????????????? fraktur bold lower
?????????????????????????? hollow upper
?????????????????????????? hollow lower
?????????????????????????? sans upper
?????????????????????????? sans lower
?????????????????????????? bold sans upper
?????????????????????????? bold sans lower
?????????????????????????? italic sans upper
?????????????????????????? italic sans lower
?????????????????????????? bold italic sans upper
?????????????????????????? bold italic sans lower
?????????????????????????? mono upper
?????????????????????????? mono lower
?????????? bold serif
?????????? hollow
?????????? sans
?????????? sans bold
?????????? mono


From harrismh777 at gmail.com  Thu Mar 27 11:28:51 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 27 Mar 2014 10:28:51 -0500
Subject: unicode as valid naming symbols
References: <lgsi07$k1p$1@speranza.aioe.org>	<mailman.8531.1395775491.18130.python-list@python.org>	<5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh1g3h$meg$1@speranza.aioe.org>

On 3/25/14 6:58 PM, Steven D'Aprano wrote:

> To quote a great Spaniard:
>
>      ?You keep using that word, I do not think it means what you
>       think it means.?

    In~con~theveable !      My name is Inigo Montoya, you killed my 
father, prepare to die...

> Do you think that the ability to write this would be an improvement?
>
> import ?
> ? = ?.??
> ? = 5*?.??
> ? = ? - 1
> ??? = [?.??**?.?*?{?|?.?} for ? in ?.?]
> ?.??????(???)

    Steven, you're killing me here; argument by analogy does not work!

    ? = lambda n: sqrt(n)      <===== but this should work...

    In point of fact, it should be built-in !   OK, IMHO.

> Of course, it's not even necessary to be that exotic. "Any unicode symbol
> that is not a number"... that means things like these:

   No, any unicode character (except numerals) should be able to begin a 
name identifier.   alt-l  ?   and  alt-v  ?   should be valid first 
character name identifier symbols.

> There are languages that can allow arbitrary symbols as identifiers, like
> Lisp and Forth. You will note that they have a certain reputation for
> being, um, different, and although both went through periods of
> considerable popularity, both have faded in popularity since.

    Actually, there is a recent resurgence of popularity in both common 
lisp and scheme these days.  But, again, that has nothing to do with my 
argument.  No modern language should limit the use of certain symbols to 
say, only math  ? .    The radical symbol is more often than not going 
to be useful only with math (which , by the way is why it should be 
built-in as  ? = squre-rooot) but why limit its use elsewhere.

    Whether this can work in python is also beside the point, because 
I'm not demanding anything here either, at this point.

have a good day!

marcus



From bjlockie at lockie.ca  Thu Mar 27 11:44:44 2014
From: bjlockie at lockie.ca (James Smith)
Date: Thu, 27 Mar 2014 08:44:44 -0700 (PDT)
Subject: regex line by line over file
In-Reply-To: <87d43f6b-8b16-4b20-8ab0-d665acac9da6@googlegroups.com>
References: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>
 <5333b7d2$0$2756$c3e8da3$76491128@news.astraweb.com>
 <87d43f6b-8b16-4b20-8ab0-d665acac9da6@googlegroups.com>
Message-ID: <681ec23b-beb4-4191-8605-8be377afb07f@googlegroups.com>

On Thursday, March 27, 2014 9:41:55 AM UTC-4, James Smith wrote:

> (134, False, '\'   "SHELF-17:LOG_COLN_IP,SC,03-25,01-18-58,NEND,NA,,,:\\\\"Log Collection In Progress\\\\",NONE:1700000035-6364-1048,:YEAR=2014,MODE=NONE"\\r\\n\'')
> 
> 
> 
> Is the \r\n on the end of the line screwing it up?

Got it.
I needed an extra \ where I had 3 in the compile.
It's kinda weird it didn't need the extra \ when I ran it manually from the shell.


From harrismh777 at gmail.com  Thu Mar 27 11:44:49 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 27 Mar 2014 10:44:49 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
Message-ID: <lh1h1f$ov3$1@speranza.aioe.org>

On 3/26/14 1:35 AM, alex23 wrote:
> On 25/03/2014 12:39 PM, Mark H Harris wrote:
>> my version semantically is "how it is perceived" by the user
>
> Could you please stop claiming to have insight into the comprehension of
> anyone other than yourself? Hasty generalisations don't help your argument.

hi alex23,  please don't be silly.

Who is being hasty?  How do you know its a generalization?

My comments here are not in the least hasty, nor are they 
generalizations. They are based on long years of experience with 
"normal" users, personal programming experience for almost 40 years, and 
insight into student perception from reader comment forms, evaluations, 
personal discussions. (sometimes from this list mind you)

It is *always* pertinent to ask, "how will this be perceived by the 
user," ehem, going all the why back to Immanuel Kant who was the first 
person (philosopher) to suggest that perception is reality.

Frankly, most of the time when I "claim" to have comprehension from 
someone other than myself its coming up with the answer to that stellar 
question (often in context with community discussion). This all amounts 
to a value add (intelligence) for community, and for comp sci.

Thinking out-loud about community perception is always valid.


marcus



From ppearson at nowhere.invalid  Thu Mar 27 11:49:02 2014
From: ppearson at nowhere.invalid (Peter Pearson)
Date: 27 Mar 2014 15:49:02 GMT
Subject: regex line by line over file
References: <a0be28b9-a1fc-460a-9063-1d25d2e293c4@googlegroups.com>
 <5333b7d2$0$2756$c3e8da3$76491128@news.astraweb.com>
 <87d43f6b-8b16-4b20-8ab0-d665acac9da6@googlegroups.com>
Message-ID: <bpivjdF4stuU1@mid.individual.net>

On Thu, 27 Mar 2014 06:41:55 -0700 (PDT), James Smith wrote:
> On Thursday, March 27, 2014 1:32:03 AM UTC-4, Steven D'Aprano wrote:
>
>> - are you mistaken about the content of the file?
>> 
>> I can't help you with the first. But the second: try running this:
>> 
>> # line2 and pat as defined above
>> filename = sys.argv[1]
>> with open(filename) as f:
>>     for line in f:
>>         print(len(line), line==line2, repr(line))
>>         print(repr(pat.match(line)))
>> 
>> which will show you what you have and whether or not it matches 
>> what you think it has. I expect that the file contents is not what 
>> you think it is, because the regex is matching the sample line.
>> 
>> Good luck!
>> 
>> -- 
>> 
>> Steven
>
> It should match this:
> (134, False, '\'   "SHELF-17:LOG[snip]MODE=NONE"\\r\\n\'')
>
> Is the \r\n on the end of the line screwing it up?

Dude, you've gotten a lot of excellent advice from some extraordinarily
capable (and patient) people, and you appear to be ignoring it.


-- 
To email me, substitute nowhere->spamcop, invalid->net.


From rustompmody at gmail.com  Thu Mar 27 11:51:39 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 27 Mar 2014 08:51:39 -0700 (PDT)
Subject: unicode as valid naming symbols
In-Reply-To: <lh1g3h$meg$1@speranza.aioe.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
Message-ID: <4e0ffd3a-8c50-4726-b214-f7b44d4e01ae@googlegroups.com>

On Thursday, March 27, 2014 8:58:51 PM UTC+5:30, Mark H. Harris wrote:
> On 3/25/14 6:58 PM, Steven D'Aprano wrote:

> > To quote a great Spaniard:
> >      ?You keep using that word, I do not think it means what you
> >       think it means.?

>     In~con~theveable !      My name is Inigo Montoya, you killed my 
> father, prepare to die...

> > Do you think that the ability to write this would be an improvement?
> > import ?
> > ? = ?.??
> > ? = 5*?.??
> > ? = ? - 1
> > ??? = [?.??**?.?*?{?|?.?} for ? in ?.?]
> > ?.??????(???)

>     Steven, you're killing me here; argument by analogy does not work!

>     ? = lambda n: sqrt(n)      <===== but this should work...

>     In point of fact, it should be built-in !   OK, IMHO.

> > Of course, it's not even necessary to be that exotic. "Any unicode symbol
> > that is not a number"... that means things like these:

>    No, any unicode character (except numerals) should be able to begin a 
> name identifier.   alt-l  ?   and  alt-v  ?   should be valid first 
> character name identifier symbols.

> > There are languages that can allow arbitrary symbols as identifiers, like
> > Lisp and Forth. You will note that they have a certain reputation for
> > being, um, different, and although both went through periods of
> > considerable popularity, both have faded in popularity since.

>     Actually, there is a recent resurgence of popularity in both common 
> lisp and scheme these days.  But, again, that has nothing to do with my 
> argument.  No modern language should limit the use of certain symbols to 
> say, only math  ? .    The radical symbol is more often than not going 
> to be useful only with math (which , by the way is why it should be 
> built-in as  ? = squre-rooot) but why limit its use elsewhere.

>     Whether this can work in python is also beside the point, because 
> I'm not demanding anything here either, at this point.

> have a good day!

The problem is that mathematicians invent notations in a completely
laissez-faire manner.

Language implementers having to unrestrainedly keep up would go mad.
And then us vanilla users (aka programmers) would have to deal with maddened
implementers.

Observe:
Good ol infix -- x+y..
prefix (with paren) -- foo(x)
prefix without  -- ? x
In case you thought alphanumerics had parens --  sin x
Then theres postfix   -- n!
Inside fix   -- nCr (Or if you prefer ?C? ??)
And outside fix -- mod -- |x|

And Ive probably forgotten 2 dozen other common ones


From harrismh777 at gmail.com  Thu Mar 27 12:03:30 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 27 Mar 2014 11:03:30 -0500
Subject: unicode as valid naming symbols
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <4e0ffd3a-8c50-4726-b214-f7b44d4e01ae@googlegroups.com>
Message-ID: <lh1i4f$rrp$1@speranza.aioe.org>

On 3/27/14 10:51 AM, Rustom Mody wrote:
>
> Observe:
> Good ol infix -- x+y..
> prefix (with paren) -- foo(x)
> prefix without  -- ? x
> In case you thought alphanumerics had parens --  sin x
> Then theres postfix   -- n!
> Inside fix   -- nCr (Or if you prefer ?C? ??)
> And outside fix -- mod -- |x|
>
> And Ive probably forgotten 2 dozen other common ones
>

Oh, I know... that's why I'm not demanding anything (what a head-ache).





From python.list at tim.thechases.com  Thu Mar 27 12:08:56 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Thu, 27 Mar 2014 11:08:56 -0500
Subject: Python language hack for C-style programmers [DO NOT USE!] :-)
Message-ID: <20140327110856.14991bb0@bigbox.christie.dr>

Multiple times, I've seen someone want something like what C-style
languages offer where assignment is done in a test, something like

  if (m = re.match(some_string)):
    do_something(m)

So when I stumbled upon this horrific atrocity of language abuse and
scope leakage, I thought I'd share it.

  if [m for m in [regex.match(some_string)] if m]:
    do_something(m)

And presto, assignment in an if-statement.  It even "works" in
while-statements too:

  while [m for m in [regex.match(some_string)] if m]:
    some_string = do_something(m)

That said, it's ugly, far more opaque/inefficient than the traditional

  m = regex.match(some_string)
  if m:
    do_something(m)

and if I ever caught someone on my dev teams doing this in production
code, their backside would receive a stern conversation with my
footwear.

Friends don't let friends program C in Python. ;-)

-tkc






From rosuav at gmail.com  Thu Mar 27 12:10:00 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 03:10:00 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lh1h1f$ov3$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
Message-ID: <CAPTjJmox2u_3-0rWtWytaXZCmGK+e3r7OS+3AJT0AL+fEiCEvQ@mail.gmail.com>

On Fri, Mar 28, 2014 at 2:44 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> My comments here are not in the least hasty, nor are they generalizations.
> They are based on long years of experience with "normal" users, personal
> programming experience for almost 40 years, and insight into student
> perception from reader comment forms, evaluations, personal discussions.
> (sometimes from this list mind you)

There is no such thing as a normal user, especially not of a
programming language. When you're writing something for a particular
class of person, you might be able to talk about the "normal user";
for instance, a word processor is most likely to be used by people who
have documents to edit, but who are not trying to do major
manipulation of a photo. Adding a caption to a photo and printing it,
maybe, but for heavy manipulation, you should be turning to something
like Gimp, so that's not part of what a normal user will be doing. You
can expect that the "normal user" of Star/Open/Libre Office's word
processor is going to be broadly familiar with page layout terms like
"header" and "footer" (or can learn such terms), and will quite
possibly understand the concept of "widows", but won't necessarily
understand, for instance, the difference between a bitmapped font and
a vector font.

But with programming languages, who's the "normal user"? Maybe there
are a few really REALLY specific-purpose languages that have the same
expectations on their users as the above example, but a
general-purpose language like Python is used by many sorts of people.
There are expert programmers who've used the language since pre 2.0
(hi Steven!); there are experienced programmers who, while not having
decades of experience with Python, do at least have an extremely solid
understanding of programming (that's where I'd put myself), with any
of several backgrounds; some have strong non-programming backgrounds
(maybe mathematical or scientific), and understand the rigors but not
necessarily the syntax (look at the recent discussion threads on
python-ideas about introducing an @ operator); there are business
people who just want to get things done; there are sysadmins or
network admins who usually use other people's tools but dabble in a
bit of scripting themselves; there are students who've just come out
of a basic Comp Sci class; and this is hardly an exhaustive list.
Every one of those people has a different set of preconceptions about
what something "ought to do". Who is a "normal user"?

ChrisA


From rosuav at gmail.com  Thu Mar 27 12:12:25 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 03:12:25 +1100
Subject: Python language hack for C-style programmers [DO NOT USE!] :-)
In-Reply-To: <20140327110856.14991bb0@bigbox.christie.dr>
References: <20140327110856.14991bb0@bigbox.christie.dr>
Message-ID: <CAPTjJmrHGXydf68Mg17xRD21E8AuKfTZwBXT8Aems59p=kiG7g@mail.gmail.com>

On Fri, Mar 28, 2014 at 3:08 AM, Tim Chase
<python.list at tim.thechases.com> wrote:
> So when I stumbled upon this horrific atrocity of language abuse and
> scope leakage, I thought I'd share it.
>
>   if [m for m in [regex.match(some_string)] if m]:
>     do_something(m)
>
> And presto, assignment in an if-statement.

And presto, it doesn't work in Python 3:

>>> if [m for m in [5] if m]:
    print(m)

Traceback (most recent call last):
  File "<pyshell#2>", line 2, in <module>
    print(m)
NameError: name 'm' is not defined

So definitely don't do it. :)

ChrisA


From rosuav at gmail.com  Thu Mar 27 12:19:40 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 03:19:40 +1100
Subject: Python language hack for C-style programmers [DO NOT USE!] :-)
In-Reply-To: <20140327110856.14991bb0@bigbox.christie.dr>
References: <20140327110856.14991bb0@bigbox.christie.dr>
Message-ID: <CAPTjJmoSEiBEO9fXfwM7mGywty+dT8erBqeu2mpyrxAf12udcw@mail.gmail.com>

On Fri, Mar 28, 2014 at 3:08 AM, Tim Chase
<python.list at tim.thechases.com> wrote:
> Multiple times, I've seen someone want something like what C-style
> languages offer where assignment is done in a test, something like
>
>   if (m = re.match(some_string)):
>     do_something(m)

If you want a language where you can do this sort of thing, but the
semantics are like Python's (first-class complex objects, garbage
collection, references instead of pointers, pass-by-object, etc),
check out Pike. Its syntax is very much C's, or C++'s or Java's if you
prefer, but it functions very much the way Python does. You can even -
and you can't do this in C or, to my knowledge, C++ - declare a
variable inside an if, which is valid only in the body of that if:

if (array m = Regexp.split2(some_pattern, some_string))
    do_something(m);

(Minor difference: Regexp.match() just returns boolean true or false,
but .split2() is more like Python's .match(). I'm not sure why there's
the difference.)

ChrisA


From ian.g.kelly at gmail.com  Thu Mar 27 12:22:40 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 27 Mar 2014 10:22:40 -0600
Subject: unicode as valid naming symbols
In-Reply-To: <lh1g3h$meg$1@speranza.aioe.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
Message-ID: <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>

On Thu, Mar 27, 2014 at 9:28 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>> Do you think that the ability to write this would be an improvement?
>>
>> import ?
>> ? = ?.??
>> ? = 5*?.??
>> ? = ? - 1
>> ??? = [?.??**?.?*?{?|?.?} for ? in ?.?]
>> ?.??????(???)
>
>
>    Steven, you're killing me here; argument by analogy does not work!

That's not an analogy.  That's an example of valid Python code if
arbitrary Unicode characters could be used to name identifiers.

>   No, any unicode character (except numerals) should be able to begin a name
> identifier.   alt-l  ?   and  alt-v  ?   should be valid first character
> name identifier symbols.

What's a numeral?  The circled numbers in the example above are
categorized as No ("Number, Other").  Currently Python only allows the
ASCII digits in numeric literals, but who's to say that ?? --
categorized as Nd ("Number, Decimal Digit") shouldn't be a valid way
to write 42?  ? seems a bit excessive for a literal, though, so should
that be permitted to start an identifier?

>> There are languages that can allow arbitrary symbols as identifiers, like
>> Lisp and Forth. You will note that they have a certain reputation for
>> being, um, different, and although both went through periods of
>> considerable popularity, both have faded in popularity since.
>
>
>    Actually, there is a recent resurgence of popularity in both common lisp
> and scheme these days.  But, again, that has nothing to do with my argument.
> No modern language should limit the use of certain symbols to say, only math
> ? .    The radical symbol is more often than not going to be useful only
> with math (which , by the way is why it should be built-in as  ? =
> squre-rooot) but why limit its use elsewhere.
>
>    Whether this can work in python is also beside the point, because I'm not
> demanding anything here either, at this point.

One of the things that Python is widely known for is its readability.
Allowing symbols such as ? to denote identifiers may be quite
expressive and appreciable to the person writing the code. However it
damages readability considerably, as seen in Steven's example above.
Personally I'm not interested in having to maintain another
programmer's code that arbitrarily uses ? as a timer function, ? as
intersection or ? as a matrix constructor.


From rosuav at gmail.com  Thu Mar 27 12:23:28 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 03:23:28 +1100
Subject: unicode as valid naming symbols
In-Reply-To: <lh1g3h$meg$1@speranza.aioe.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
Message-ID: <CAPTjJmqviFZgMSAUpno1TKzyyj4zhNO3JGhXHPZP371vHxOpew@mail.gmail.com>

On Fri, Mar 28, 2014 at 2:28 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>   No, any unicode character (except numerals) should be able to begin a name
> identifier.   alt-l  ?   and  alt-v  ?   should be valid first character
> name identifier symbols.
>

What, even whitespace??

ChrisA


From harrismh777 at gmail.com  Thu Mar 27 12:24:24 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 27 Mar 2014 11:24:24 -0500
Subject: Reading in cooked mode (was Re: Python MSI not installing, log
 file showing name of a Viatnemese communist revolutionary)
In-Reply-To: <mailman.8548.1395790718.18130.python-list@python.org>
References: <mailman.8409.1395538666.18130.python-list@python.org>
 <532f9a6b$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8433.1395631040.18130.python-list@python.org>
 <lgo9v1$b3i$1@speranza.aioe.org>
 <mailman.8470.1395703845.18130.python-list@python.org>
 <lgqg92$a2v$2@speranza.aioe.org>
 <mailman.8548.1395790718.18130.python-list@python.org>
Message-ID: <533450B8.3040309@gmail.com>

On 3/25/14 6:38 PM, Dennis Lee Bieber wrote:
>>
> 	A couple of us managed to "steal" the school login/password (don't
> think we ever used it, but...)... The teaching assistant didn't notice the
> paper tape punch was active when persuaded to login to let us run a short
> program (high school BASIC class, with a dial-up teletype). Playing back
> the tape and manually spinning the platen during the password
> obscuration/input phase gave us the plain text.
>

I still have one of my old BASIC tapes from way back in the day; I 
wanted to get the code back, or just remember why I had saved the tape?

One of my linux user group buddies locally rigged up an optical reader 
(IF) to a single board micro controller... we pulled the tape by hand 
using the center drive holes (sprocket holes) as a strobe and after a 
couple of false attempts read the entire tape into a text file.

That tape still have the caster oil smell of the tty that produced it; 
smell has a very strong memory association /  I can still hear that 
thing running in my head.  ... haven't seen one physically in years.

marcus



From harrismh777 at gmail.com  Thu Mar 27 12:24:24 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 27 Mar 2014 11:24:24 -0500
Subject: Reading in cooked mode (was Re: Python MSI not installing, log
 file showing name of a Viatnemese communist revolutionary)
References: <mailman.8409.1395538666.18130.python-list@python.org>
 <532f9a6b$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8433.1395631040.18130.python-list@python.org>
 <lgo9v1$b3i$1@speranza.aioe.org>
 <mailman.8470.1395703845.18130.python-list@python.org>
 <lgqg92$a2v$2@speranza.aioe.org>
 <mailman.8548.1395790718.18130.python-list@python.org>
Message-ID: <533450B8.3040309@gmail.com>

On 3/25/14 6:38 PM, Dennis Lee Bieber wrote:
>>
> 	A couple of us managed to "steal" the school login/password (don't
> think we ever used it, but...)... The teaching assistant didn't notice the
> paper tape punch was active when persuaded to login to let us run a short
> program (high school BASIC class, with a dial-up teletype). Playing back
> the tape and manually spinning the platen during the password
> obscuration/input phase gave us the plain text.
>

I still have one of my old BASIC tapes from way back in the day; I 
wanted to get the code back, or just remember why I had saved the tape?

One of my linux user group buddies locally rigged up an optical reader 
(IF) to a single board micro controller... we pulled the tape by hand 
using the center drive holes (sprocket holes) as a strobe and after a 
couple of false attempts read the entire tape into a text file.

That tape still have the caster oil smell of the tty that produced it; 
smell has a very strong memory association /  I can still hear that 
thing running in my head.  ... haven't seen one physically in years.

marcus



From harrismh777 at gmail.com  Thu Mar 27 12:37:36 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 27 Mar 2014 11:37:36 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <mailman.8623.1395936604.18130.python-list@python.org>
Message-ID: <lh1k4e$1il$1@speranza.aioe.org>

On 3/27/14 11:10 AM, Chris Angelico wrote:
> On Fri, Mar 28, 2014 at 2:44 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>> My comments here are not in the least hasty, nor are they generalizations.
>> They are based on long years of experience with "normal" users, {snip}


> Who is a "normal user"?

For the purposes of this list, a "normal" user is a reasonably 
intelligent college educated non "computer professional" non "computer 
scientist" non "expert" who for the moment has an interest in leveraging 
computer science and|or programming to solve everyday or other 
scientific problems (without) having to first become a computer 
professional, computer scientist, or expert.

Yes, there are many many of them. There are hundreds of millions of them 
in the world today.  There are only a handful of "experts" world-wide.

This "normal" set excludes power users, expert users, special purpose 
users and computer scientists. The "normal" users are those folks who 
want to get real answers to real problems *without* having to spend eons 
of time learning how to use the system. Enter python, SimplyPy, short 
tutorial (and on-line python docs) and whalla.

Now for Immanuel Kant (perception is reality); what do "normal" users 
expect?  Its the ten-million ?uro question.

marcus



From tade.ankur at gmail.com  Thu Mar 27 12:40:52 2014
From: tade.ankur at gmail.com (tade.ankur at gmail.com)
Date: Thu, 27 Mar 2014 09:40:52 -0700 (PDT)
Subject: SSL: DECRYPTION_FAILED_OR_BAD_RECORD_MAC
Message-ID: <94cfb444-8c5d-4b2c-b08c-29170991d02b@googlegroups.com>


hei , 

I am a newcome to Python. 

I am trying to create a python script which will connect to an SSL URL and using the HEAD request will get the status of URL. 

For one the link I am getting following error

[SSL: DECRYPTION_FAILED_OR_BAD_RECORD_MAC] decryption failed or bad record mac (_ssl.c:589)

I am using python on windows. 

Following is the code snippet

def checkURLStatusSecure(testhostname,urlsinatest):
    global conn, url, res

    for url in urlsinatest:
        conn = HTTPSConnection(testhostname,'443')
        conn.request('HEAD', url)
        res = conn.getresponse()
        print('|***https://' + testhostname + url + '| %s | %s |' % (res.status, res.reason))
        res.close()
        conn.close()

Any idea why I am gtting the above mentioned error. 

Any help will be appreciable 

Python version in 3.4


From rosuav at gmail.com  Thu Mar 27 12:48:44 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 03:48:44 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lh1k4e$1il$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <mailman.8623.1395936604.18130.python-list@python.org>
 <lh1k4e$1il$1@speranza.aioe.org>
Message-ID: <CAPTjJmqOmnni7YREwQThmO58yKcRAqNmsvCnC4Ji2so7HrjjeQ@mail.gmail.com>

On Fri, Mar 28, 2014 at 3:37 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> For the purposes of this list, a "normal" user is a reasonably intelligent
> college educated non "computer professional" non "computer scientist" non
> "expert" who for the moment has an interest in leveraging computer science
> and|or programming to solve everyday or other scientific problems (without)
> having to first become a computer professional, computer scientist, or
> expert.

Now you have to justify: Why is this person considered normal?

ChrisA


From python at mrabarnett.plus.com  Thu Mar 27 13:17:04 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Thu, 27 Mar 2014 17:17:04 +0000
Subject: unicode as valid naming symbols
In-Reply-To: <4e0ffd3a-8c50-4726-b214-f7b44d4e01ae@googlegroups.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <4e0ffd3a-8c50-4726-b214-f7b44d4e01ae@googlegroups.com>
Message-ID: <53345D10.8060303@mrabarnett.plus.com>

On 2014-03-27 15:51, Rustom Mody wrote:
> On Thursday, March 27, 2014 8:58:51 PM UTC+5:30, Mark H. Harris wrote:
>> On 3/25/14 6:58 PM, Steven D'Aprano wrote:
>
>> > To quote a great Spaniard:
>> >      ?You keep using that word, I do not think it means what you
>> >       think it means.?
>
>>     In~con~theveable !      My name is Inigo Montoya, you killed my
>> father, prepare to die...
>
>> > Do you think that the ability to write this would be an improvement?
>> > import ?
>> > ? = ?.??
>> > ? = 5*?.??
>> > ? = ? - 1
>> > ??? = [?.??**?.?*?{?|?.?} for ? in ?.?]
>> > ?.??????(???)
>
>>     Steven, you're killing me here; argument by analogy does not work!
>
>>     ? = lambda n: sqrt(n)      <===== but this should work...
>
>>     In point of fact, it should be built-in !   OK, IMHO.
>
>> > Of course, it's not even necessary to be that exotic. "Any unicode symbol
>> > that is not a number"... that means things like these:
>
>>    No, any unicode character (except numerals) should be able to begin a
>> name identifier.   alt-l  ?   and  alt-v  ?   should be valid first
>> character name identifier symbols.
>
>> > There are languages that can allow arbitrary symbols as identifiers, like
>> > Lisp and Forth. You will note that they have a certain reputation for
>> > being, um, different, and although both went through periods of
>> > considerable popularity, both have faded in popularity since.
>
>>     Actually, there is a recent resurgence of popularity in both common
>> lisp and scheme these days.  But, again, that has nothing to do with my
>> argument.  No modern language should limit the use of certain symbols to
>> say, only math  ? .    The radical symbol is more often than not going
>> to be useful only with math (which , by the way is why it should be
>> built-in as  ? = squre-rooot) but why limit its use elsewhere.
>
>>     Whether this can work in python is also beside the point, because
>> I'm not demanding anything here either, at this point.
>
>> have a good day!
>
> The problem is that mathematicians invent notations in a completely
> laissez-faire manner.
>
> Language implementers having to unrestrainedly keep up would go mad.
> And then us vanilla users (aka programmers) would have to deal with maddened
> implementers.
>
> Observe:
> Good ol infix -- x+y..
> prefix (with paren) -- foo(x)
> prefix without  -- ? x
> In case you thought alphanumerics had parens --  sin x
> Then theres postfix   -- n!
> Inside fix   -- nCr (Or if you prefer ?C? ??)
> And outside fix -- mod -- |x|
>
> And Ive probably forgotten 2 dozen other common ones
>
You haven't mentioned implicit multiplication: xy

Then there's raising to a power sin?(x), except that what looks like
raising to -1 actually means the inverse function (arcsin).



From rustompmody at gmail.com  Thu Mar 27 13:41:54 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 27 Mar 2014 10:41:54 -0700 (PDT)
Subject: unicode as valid naming symbols
In-Reply-To: <mailman.8626.1395937404.18130.python-list@python.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <mailman.8626.1395937404.18130.python-list@python.org>
Message-ID: <1c37ed11-32fd-4670-b364-df117c3a0aa5@googlegroups.com>

On Thursday, March 27, 2014 9:52:40 PM UTC+5:30, Ian wrote:
> On Thu, Mar 27, 2014 at 9:28 AM, Mark H Harris wrote:
> >> Do you think that the ability to write this would be an improvement?
> >> import ?
> >> ? = ?.??
> >> ? = 5*?.??
> >> ? = ? - 1
> >> ??? = [?.??**?.?*?{?|?.?} for ? in ?.?]
> >> ?.??????(???)
> >    Steven, you're killing me here; argument by analogy does not work!

> That's not an analogy.  That's an example of valid Python code if
> arbitrary Unicode characters could be used to name identifiers.

Python has other lexical categories than identifier-chars eg operators.
Enriching that set is a somewhat different direction from 
enriching the identifier charset.

Note both these directions are valid bit different
This table http://www.unicode.org/charts/PDF/U2200.pdf
looks unpleasantly overfilled.  However good deal is stylistic differences
? vs ? and sometimes even indistinguishable ? vs ?.

If we accept that python is more readable than Cobol, having a good
selection from the above makes for a programming language more readable in an
analogous manner.


From rustompmody at gmail.com  Thu Mar 27 13:53:40 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 27 Mar 2014 10:53:40 -0700 (PDT)
Subject: unicode as valid naming symbols
In-Reply-To: <mailman.8630.1395940631.18130.python-list@python.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <4e0ffd3a-8c50-4726-b214-f7b44d4e01ae@googlegroups.com>
 <mailman.8630.1395940631.18130.python-list@python.org>
Message-ID: <8606888e-4819-4440-a652-7127c0056934@googlegroups.com>

On Thursday, March 27, 2014 10:47:04 PM UTC+5:30, MRAB wrote:
> On 2014-03-27 15:51, Rustom Mody wrote:
> > On Thursday, March 27, 2014 8:58:51 PM UTC+5:30, Mark H. Harris wrote:
> >> On 3/25/14 6:58 PM, Steven D'Aprano wrote:
> >> > To quote a great Spaniard:
> >> >      ?You keep using that word, I do not think it means what you
> >> >       think it means.?
> >>     In~con~theveable !      My name is Inigo Montoya, you killed my
> >> father, prepare to die...
> >> > Do you think that the ability to write this would be an improvement?
> >> > import ?
> >> > ? = ?.??
> >> > ? = 5*?.??
> >> > ? = ? - 1
> >> > ??? = [?.??**?.?*?{?|?.?} for ? in ?.?]
> >> > ?.??????(???)
> >>     Steven, you're killing me here; argument by analogy does not work!
> >>     ? = lambda n: sqrt(n)      <===== but this should work...
> >>     In point of fact, it should be built-in !   OK, IMHO.
> >> > Of course, it's not even necessary to be that exotic. "Any unicode symbol
> >> > that is not a number"... that means things like these:
> >>    No, any unicode character (except numerals) should be able to begin a
> >> name identifier.   alt-l  ?   and  alt-v  ?   should be valid first
> >> character name identifier symbols.
> >> > There are languages that can allow arbitrary symbols as identifiers, like
> >> > Lisp and Forth. You will note that they have a certain reputation for
> >> > being, um, different, and although both went through periods of
> >> > considerable popularity, both have faded in popularity since.
> >>     Actually, there is a recent resurgence of popularity in both common
> >> lisp and scheme these days.  But, again, that has nothing to do with my
> >> argument.  No modern language should limit the use of certain symbols to
> >> say, only math  ? .    The radical symbol is more often than not going
> >> to be useful only with math (which , by the way is why it should be
> >> built-in as  ? = squre-rooot) but why limit its use elsewhere.
> >>     Whether this can work in python is also beside the point, because
> >> I'm not demanding anything here either, at this point.
> >> have a good day!
> > The problem is that mathematicians invent notations in a completely
> > laissez-faire manner.
> > Language implementers having to unrestrainedly keep up would go mad.
> > And then us vanilla users (aka programmers) would have to deal with maddened
> > implementers.
> > Observe:
> > Good ol infix -- x+y..
> > prefix (with paren) -- foo(x)
> > prefix without  -- ? x
> > In case you thought alphanumerics had parens --  sin x
> > Then theres postfix   -- n!
> > Inside fix   -- nCr (Or if you prefer ?C? ??)
> > And outside fix -- mod -- |x|
> > And Ive probably forgotten 2 dozen other common ones

> You haven't mentioned implicit multiplication: xy

Yeah -- thats a bad one!

Can mean 
- ordinary multiply (if you are in school)
- overloaded (scalar-field or scalar-vector) multiply in linear algebra
- function application (tensors??)
- concatenation (awk, snobol (with space))
- a 2 char variable (for 'normal' (whatever that means) programmer)

> Then there's raising to a power sin?(x), except that what looks like
> raising to -1 actually means the inverse function (arcsin).

Non-linear notations is another can (barrel?) of worms
Matrices/Determinants anyone?

Yeah... Copying the *notations* of mathematicians is not such a great idea.

And yet doing away with it too summarily leads to Cobol, Sql etc.
The math remains willy-nilly... just under a steaming pile of alphanumeriage.


From delldudedevin at gmail.com  Thu Mar 27 16:02:49 2014
From: delldudedevin at gmail.com (Devin)
Date: Thu, 27 Mar 2014 13:02:49 -0700
Subject: CentOS 6.5 / SPEC file
Message-ID: <CAEctU6pmKni6f1wd31dUggOHLtwXBt=JeZ4G6Uh10+1n8=5_xg@mail.gmail.com>

I have been trying to compile an RPM manually using the SPEC file that is
contained in the source tarball from Python.org's website. I have tried
multiple versions and they all seem to fail. I have tried the latest 3.4.0
release, 3.3.5 release, and 3.2.5 release. It appears the SPEC file
contained in the Misc/RPM directory is broken.

I am seeing the error:

+ '[' '!' -z 2.6 ']'
+ cd /builddir/build/BUILDROOT/python2.6-3.3.5-1pydotorg.x86_64/usr/bin
+ mv pydoc pydoc.old
mv: cannot stat `pydoc': No such file or directory
RPM build errors:
error: Bad exit status from /var/tmp/rpm-tmp.yqWO6C (%install)
    line 71: buildprereq is deprecated: BuildPrereq: expat-devel
    line 72: buildprereq is deprecated: BuildPrereq: db4-devel
    line 73: buildprereq is deprecated: BuildPrereq: gdbm-devel
    line 74: buildprereq is deprecated: BuildPrereq: sqlite-devel
    line 91: prereq is deprecated: Prereq: python2.6 = %{PACKAGE_VERSION}
    line 122: prereq is deprecated: Prereq: python2.6 =
%{PACKAGE_VERSION}-1pydotorg
    Bad exit status from /var/tmp/rpm-tmp.yqWO6C (%install)

It seems to give me this error regardless of what version of Python I am
trying. Is there a good website that contains maybe a more correct version
of the SPEC file for CentOS 6.x? Any help would be greatly appreciated.

Devin Acosta
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From harrismh777 at gmail.com  Thu Mar 27 16:54:40 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 27 Mar 2014 15:54:40 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <mailman.8623.1395936604.18130.python-list@python.org>
 <lh1k4e$1il$1@speranza.aioe.org>
 <mailman.8629.1395938933.18130.python-list@python.org>
Message-ID: <lh236d$bcv$1@speranza.aioe.org>

On 3/27/14 11:48 AM, Chris Angelico wrote:
> On Fri, Mar 28, 2014 at 3:37 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>> For the purposes of this list, a "normal" user is a reasonably intelligent
>> college educated non "computer professional" non "computer scientist" non
>> "expert" who for the moment has an interest in leveraging computer science
>> and|or programming to solve everyday or other scientific problems (without)
>> having to first become a computer professional, computer scientist, or
>> expert.
>
> Now you have to justify: Why is this person considered normal?
>

Do not think "normal" vs. "abnormal". That would be missing the mark.

"Normal" are the folks that fall (more or less) within two standard 
deviations from the mean on a normal distribution of reasonably 
intelligent, college educated scientists, and other problem solvers, who 
have not been trained in the liberal art of programming (software 
engineering) and who have an aptitude for problem solving but for 
whatever reason (including time and interest) have not been inclined so 
far towards the practical art of coding within the giant sphere of 
computer science. Of course you eliminate from the set out-lyres and 
almost all +|- outside two standard deviations of the mean (maybe a 
little more).

The set includes most human beings on the planet. These are non computer 
language experts, non computer scientists generally, non data processing 
professionals, &c.   These folks called "normal" are comprised of 
everyone else who is smart enough to use a computer but does not have 
eons to be initiated in the fine nuances of language design nor software 
engineering.  They just want to push their problem in, and get their 
result out--- relatively quickly, with minimal hassle.

Jeane, on the list this week, is an example of this kind of person.

Yes, its possible. Dartmouth proved it (graduate students before 
computer science was invented) in 1963-1964. Gates proved it again with 
his BASICA, visual BASIC, and GWBASIC.  There has been a resurgence of 
interest in this area on tablets with Mintoris BASIC. On the PC and MAC 
with Chipmunk BASIC... and others.

I am going to give this a shot with python. I honestly believe that the 
python language can be leveraged in a minimal way (without being 
minimalist) and at the same time in a sophisticated nuanced way (without 
harming the flexibility of the language) for expert users and developers.

Some people equate developer with programmer with software engineer. 
This ought not be done, in my view. There are *many* programmers out 
there who suck at software engineering (and they are not computer 
scientists).  They also do not qualify as developers.

But they are problem solvers, and they can leverage the power of python 
in a minimal way to solve their problems (fast, efficient) in a modern 
sense. We have the web now. We use databases now. Problem solvers need 
sockets now (server side, client side) that are *easy*. Mathematica is 
too complicated. Matlab the same. My idea is to unify, simplify and give 
access to the underlying language essentials system and interpreter 
(like they did in 1964) to make things easier to pick up and go.

-------

When I started at this gig someone pointed to the O'Reilly book (about 
1590) pages) and python.org.  Give me a break!

No.  We need a quick starter subset, a tiny book, and even tinier 
tutorial, that gets people ("normal" ones) a fast boot to productive 
work, yes, with pointers into more extensive reading and experimenting.
One day, they will be at least general-users, if not super-users or 
experts. They may never be python developers and that's ok.

Philosophy by me


marcus




From fred.sells at adventistcare.org  Thu Mar 27 16:56:56 2014
From: fred.sells at adventistcare.org (Sells, Fred)
Date: Thu, 27 Mar 2014 20:56:56 +0000
Subject: meta language to define forms
Message-ID: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>

I'm trying to use python classes and members to define complex data entry forms as a meta language

The idea is to use a nice clean syntax like Python to define form content, then render it as HTML but only as a review tool for users,  The actual rendering would go into a database to let a vendor's tool generate the form in a totally non-standard syntax that's really clunky.

I don't have a lot of time or management support to do something elegant like XML and then parse it, I'm thinking more like

Class  FyFormNumber001(GeneralForm):
	Section1 = Section(title="Enter Patient Vital Signs")
		Question1 = NumberQuestion(title="Enter pulse rate", format="%d3")
		Question2 = Dropdown(title="Enter current status")
		Question2.choices = [ (1, "Alive and Kicking"), (2, "Comatose"), (3, "Dead"), ...]


Of course this is not quite legal python and I have a lot of flexibility in my "meta" language.  The basic model is that a single file would define a form which would have one or more sections,  each section would have one or more questions of various types (i.e. checkbox, radio button, text, etc).  Sections cannot be nested.

I don't have to have a perfect layout, just close enough to get the end users to focus on what they are asking for before we generate the actual code.  I tried an HTML WYSIWYG editor but that was too slow and I lost information that I need to retain when the actual form is generated.

The biggest problem (to me) is that I have to maintain the order; i.e. the order in which they are coded should be the order in which they are displayed.

I'm looking to do about 200 forms, so it is reasonable to invest some time up front to make the process work; meanwhile management wants results yesterday, so I have a trade-off to make.

Is there anything out there that would be close or do you have any suggestions.

Thanks.

From tjreedy at udel.edu  Thu Mar 27 17:10:30 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 27 Mar 2014 17:10:30 -0400
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
 <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
Message-ID: <lh2444$u2k$1@ger.gmane.org>

On 3/27/2014 7:42 AM, Chris Angelico wrote:

> In any case... what I'd suggest would be opening a tracker issue, or
> discussing this on python-ideas, and seeing what core devs think of
> the matter. I think that, on balance, it's probably better to show the
> whole thing with the same sign; but should it be:

Before doing so, I suggest looking for the design discussion either on 
the tracker or in python-ideas or py-dev lists.


>>>> str(datetime.timedelta(-1, -1))
> '-1 day, 00:00:01'
>
> or should the hyphen be repeated:
>
>>>> str(datetime.timedelta(-1, -1))
> '-1 day, -00:00:01'

'-(1 day, 00:00:01)' should be unambiguous.

-- 
Terry Jan Reedy



From torriem at gmail.com  Thu Mar 27 17:26:31 2014
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 27 Mar 2014 15:26:31 -0600
Subject: CentOS 6.5 / SPEC file
In-Reply-To: <CAEctU6pmKni6f1wd31dUggOHLtwXBt=JeZ4G6Uh10+1n8=5_xg@mail.gmail.com>
References: <CAEctU6pmKni6f1wd31dUggOHLtwXBt=JeZ4G6Uh10+1n8=5_xg@mail.gmail.com>
Message-ID: <53349787.3080301@gmail.com>

On 03/27/2014 02:02 PM, Devin wrote:
> RPM build errors:
> error: Bad exit status from /var/tmp/rpm-tmp.yqWO6C (%install)
>     line 71: buildprereq is deprecated: BuildPrereq: expat-devel
>     line 72: buildprereq is deprecated: BuildPrereq: db4-devel
>     line 73: buildprereq is deprecated: BuildPrereq: gdbm-devel
>     line 74: buildprereq is deprecated: BuildPrereq: sqlite-devel
>     line 91: prereq is deprecated: Prereq: python2.6 = %{PACKAGE_VERSION}
>     line 122: prereq is deprecated: Prereq: python2.6 =
> %{PACKAGE_VERSION}-1pydotorg
>     Bad exit status from /var/tmp/rpm-tmp.yqWO6C (%install)
> 
> It seems to give me this error regardless of what version of Python I am
> trying. Is there a good website that contains maybe a more correct version
> of the SPEC file for CentOS 6.x? Any help would be greatly appreciated.

Try changing BuildPrereq to BuildRequires.

Also what I'd do is grab a SRPM for python3 from, say Fedora 18 or 19,
and drop in the newer tarball and see how it goes.



From rosuav at gmail.com  Thu Mar 27 17:42:50 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 08:42:50 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lh236d$bcv$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <mailman.8623.1395936604.18130.python-list@python.org>
 <lh1k4e$1il$1@speranza.aioe.org>
 <mailman.8629.1395938933.18130.python-list@python.org>
 <lh236d$bcv$1@speranza.aioe.org>
Message-ID: <CAPTjJmpzNooSWZQMz5x2-wQz_CopQtTXkEuw4KKDuHNPAULDaA@mail.gmail.com>

On Fri, Mar 28, 2014 at 7:54 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> Some people equate developer with programmer with software engineer. This
> ought not be done, in my view. There are *many* programmers out there who
> suck at software engineering (and they are not computer scientists).  They
> also do not qualify as developers.

And this is the bit where, I think, we disagree. I think that
programming is for programmers, in the same way that music is for
musicians and the giving of legal advice is for lawyers. Yes, there
are armchair lawyers, and plenty of people can pick up a hymn book and
sing; but laws and operas aren't designed with them in mind. Why
should programming languages be designed for the people who don't want
to learn them?

ChrisA


From torriem at gmail.com  Thu Mar 27 17:45:29 2014
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 27 Mar 2014 15:45:29 -0600
Subject: CentOS 6.5 / SPEC file
In-Reply-To: <53349787.3080301@gmail.com>
References: <CAEctU6pmKni6f1wd31dUggOHLtwXBt=JeZ4G6Uh10+1n8=5_xg@mail.gmail.com>
 <53349787.3080301@gmail.com>
Message-ID: <53349BF9.2020400@gmail.com>

On 03/27/2014 03:26 PM, Michael Torrie wrote:
> On 03/27/2014 02:02 PM, Devin wrote:
>> RPM build errors:
>> error: Bad exit status from /var/tmp/rpm-tmp.yqWO6C (%install)
>>     line 71: buildprereq is deprecated: BuildPrereq: expat-devel
>>     line 72: buildprereq is deprecated: BuildPrereq: db4-devel
>>     line 73: buildprereq is deprecated: BuildPrereq: gdbm-devel
>>     line 74: buildprereq is deprecated: BuildPrereq: sqlite-devel
>>     line 91: prereq is deprecated: Prereq: python2.6 = %{PACKAGE_VERSION}
>>     line 122: prereq is deprecated: Prereq: python2.6 =
>> %{PACKAGE_VERSION}-1pydotorg
>>     Bad exit status from /var/tmp/rpm-tmp.yqWO6C (%install)
>>
>> It seems to give me this error regardless of what version of Python I am
>> trying. Is there a good website that contains maybe a more correct version
>> of the SPEC file for CentOS 6.x? Any help would be greatly appreciated.
> 
> Try changing BuildPrereq to BuildRequires.
> 
> Also what I'd do is grab a SRPM for python3 from, say Fedora 18 or 19,
> and drop in the newer tarball and see how it goes.

I should add, that the only correct way to package Python 3 on RHEL 6 is
by making the package called "python3" or something that won't collide
with the system Python 2.x package.  Python (2.x) is a required package
on RHEL and if you replace it with Python 3 you'll see just about
everything cease to function.


From harrismh777 at gmail.com  Thu Mar 27 18:14:09 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 27 Mar 2014 17:14:09 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <mailman.8623.1395936604.18130.python-list@python.org>
 <lh1k4e$1il$1@speranza.aioe.org>
 <mailman.8629.1395938933.18130.python-list@python.org>
 <lh236d$bcv$1@speranza.aioe.org>
 <mailman.8637.1395956573.18130.python-list@python.org>
Message-ID: <5334A2B1.20006@gmail.com>

On 3/27/14 4:42 PM, Chris Angelico wrote:
> And this is the bit where, I think, we disagree. I think that
> programming is for programmers, in the same way that music is for
> musicians and the giving of legal advice is for lawyers. Yes, there
> are armchair lawyers, and plenty of people can pick up a hymn book and
> sing;
------------------------------------
> but laws and operas aren't designed with them in mind. Why
> should programming languages be designed for the people who don't want
> to learn them?

Actually we agree quite a bit on this--I agree with everything above the 
line----- and some of the sentiment with everything below the line.

Your question has a somewhat false premise. They *really do* want to 
learn them, and they are frustrated with the time and attention it 
takes. The argument is also from analogy, which in this case is almost 
similar but not quite.

Now, there is no royal road to geometry, opera, the violin, and the 
piano (I'm a pianist, and flutist--and an amateur composer). All of 
these fine arts take time, there is just no getting around it. However, 
there are now "computer based" piano courses that speed the process 
(with 44 key keyboard) by factors of 10. In other words, its easier now 
because of computers, to learn to play the piano on ones own time than 
ever before. To be really good at it, you're going to need to get a good 
instructor and work.  Opera, the violin, pole vaulting, are all in 
another category requiring talent!  ... not just will, and brains.

Here in the states we file a little thing on or around April 15 called a 
tax return.  Well most of us these days file electronically, and most of 
us doing that use some kind of tax software that takes in all the data, 
organizes it, and gives it to the Internal Revenue Service in a format 
that is legal, is accurate, and leads to no audit; because its just 
right.  That is more of what I'm talking about.  I have no interest in 
becoming a tax accountant, nor making money doing taxes for others, but, 
I do want to submit my correct return on time with no errors, and from 
my own keyboard (fast, efficient, error free, and with no driving, 
stamping, mailing, &c).

People want to use their computer. They want to solve problems with 
it... and frankly, they would like to know how to program it, if there 
where some royal road, or fast track, or short and easy tutorial. I know 
lots of people that will sit down and try (with a cup of Java) and hack 
it out if they have a good short book.

Python IMHO is the perfect language to give this a shot with--- 
powerful, elegant, easy once initiated, fast, and most important 
extensible and flexible.

"normal" people deserve this.  Well, I'll know if nobody buys the book, 
nor downloads the package, nor submits bug reports. But, I've got an 
inkling that there is a need, all over the place.

Just look on the list:  Fred Sells meta language request.  He proves my 
point entirely.  I have not responded yet... thought I would wait a 
bit... but look what he is after.  Go read it.

But, I don't disagree with you Chris, and I have myself some of the same 
concerns really. I'm finding the path harder than I thought it would be. 
Well, its hard enough just getting other people who are experts to buy 
into it.  Its going to be an uphill climb, for sure.

marcus



From harrismh777 at gmail.com  Thu Mar 27 18:14:09 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Thu, 27 Mar 2014 17:14:09 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <mailman.8637.1395956573.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <mailman.8623.1395936604.18130.python-list@python.org>
 <lh1k4e$1il$1@speranza.aioe.org>
 <mailman.8629.1395938933.18130.python-list@python.org>
 <lh236d$bcv$1@speranza.aioe.org>
 <mailman.8637.1395956573.18130.python-list@python.org>
Message-ID: <5334A2B1.20006@gmail.com>

On 3/27/14 4:42 PM, Chris Angelico wrote:
> And this is the bit where, I think, we disagree. I think that
> programming is for programmers, in the same way that music is for
> musicians and the giving of legal advice is for lawyers. Yes, there
> are armchair lawyers, and plenty of people can pick up a hymn book and
> sing;
------------------------------------
> but laws and operas aren't designed with them in mind. Why
> should programming languages be designed for the people who don't want
> to learn them?

Actually we agree quite a bit on this--I agree with everything above the 
line----- and some of the sentiment with everything below the line.

Your question has a somewhat false premise. They *really do* want to 
learn them, and they are frustrated with the time and attention it 
takes. The argument is also from analogy, which in this case is almost 
similar but not quite.

Now, there is no royal road to geometry, opera, the violin, and the 
piano (I'm a pianist, and flutist--and an amateur composer). All of 
these fine arts take time, there is just no getting around it. However, 
there are now "computer based" piano courses that speed the process 
(with 44 key keyboard) by factors of 10. In other words, its easier now 
because of computers, to learn to play the piano on ones own time than 
ever before. To be really good at it, you're going to need to get a good 
instructor and work.  Opera, the violin, pole vaulting, are all in 
another category requiring talent!  ... not just will, and brains.

Here in the states we file a little thing on or around April 15 called a 
tax return.  Well most of us these days file electronically, and most of 
us doing that use some kind of tax software that takes in all the data, 
organizes it, and gives it to the Internal Revenue Service in a format 
that is legal, is accurate, and leads to no audit; because its just 
right.  That is more of what I'm talking about.  I have no interest in 
becoming a tax accountant, nor making money doing taxes for others, but, 
I do want to submit my correct return on time with no errors, and from 
my own keyboard (fast, efficient, error free, and with no driving, 
stamping, mailing, &c).

People want to use their computer. They want to solve problems with 
it... and frankly, they would like to know how to program it, if there 
where some royal road, or fast track, or short and easy tutorial. I know 
lots of people that will sit down and try (with a cup of Java) and hack 
it out if they have a good short book.

Python IMHO is the perfect language to give this a shot with--- 
powerful, elegant, easy once initiated, fast, and most important 
extensible and flexible.

"normal" people deserve this.  Well, I'll know if nobody buys the book, 
nor downloads the package, nor submits bug reports. But, I've got an 
inkling that there is a need, all over the place.

Just look on the list:  Fred Sells meta language request.  He proves my 
point entirely.  I have not responded yet... thought I would wait a 
bit... but look what he is after.  Go read it.

But, I don't disagree with you Chris, and I have myself some of the same 
concerns really. I'm finding the path harder than I thought it would be. 
Well, its hard enough just getting other people who are experts to buy 
into it.  Its going to be an uphill climb, for sure.

marcus



From steve+comp.lang.python at pearwood.info  Thu Mar 27 19:41:59 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 27 Mar 2014 23:41:59 GMT
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
Message-ID: <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 27 Mar 2014 08:52:24 -0400, Roy Smith wrote:

> In article <mailman.8613.1395917059.18130.python-list at python.org>,
>  Chris Angelico <rosuav at gmail.com> wrote:
>> It's not "equally braindead", it follows a simple and logical rule:
>> Only the day portion is negative.
> 
> Simple and logical, yes.  But also entirely braindead.

Do you think it is "braindead" for __str__ to return something which 
follows the internal representation of the object?

Note that I'm not asking if that is the best choice for every object, or 
even the best choice for any object. You've made an extremely strong 
claim, by calling something "braindead" you're essentially arguing that 
this is an *utterly irredeemable choice whatsoever* with absolutely no 
redeeming features.

Hyperbole is fun, that's why we do it. It allows us to build up a nice 
feeling of righteous indignation over something utterly outrageous and 
indefensible, without having to worry about inconvenient distractions 
like other points of view :-)


>> That might not be perfectly suited to all situations
> 
> Give ma a real-life situation where you would want such behavior.

Easy -- I'm debugging timedelta routines, and I want to easily see that 
the timedeltas calculated match what I expect them to be when I print 
them. The quickest, easiest and simplest way is for str(timedelta) to 
follow the internal representation.

Oh look, that's exactly what the docs say:

"String representations of timedelta objects are normalized similarly to 
their internal representation. This leads to somewhat unusual results for 
negative timedeltas."

as Skip has already pointed out.

Is this the *best* choice for a timedelta? Probably not. But it's a 
simple, logical, *reasonable* choice. It only fails the "reasonable" test 
if you insist that timedelta objects *must* match the time-keeping 
conventions of native English speakers, and any other convention is 
unspeakable. For all we know, maybe (say) Koreans or Egyptians or Gaelic 
Scots do say something like "It was a day ago, less four hours" meaning 
twenty hours ago. Stranger things happen in natural language, and we 
ought to be cautious about insisting that English conventions are 
universal.

(Given Johannes Bauer's reaction, we can be fairly certain that German 
speakers follow a similar convention to English speakers. Which shouldn't 
be terribly surprising, since English is a Germanic language.)


A few seconds searching the bug tracker shows that this is not, in fact, 
a bug in timedelta but probably a deliberate feature:

http://bugs.python.org/issue9430

This one is also relevant: http://bugs.python.org/issue1569623


Alas, the discussion appears to have been on #python-dev, which 
(probably) means it is not archived anywhere.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From drsalists at gmail.com  Thu Mar 27 19:45:19 2014
From: drsalists at gmail.com (Dan Stromberg)
Date: Thu, 27 Mar 2014 16:45:19 -0700
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
Message-ID: <CAGGBd_o=QDqswOamapSZuuSw_TeEZjNitE1y5Dou7S3jxprX3Q@mail.gmail.com>

On Fri, Mar 21, 2014 at 1:42 PM, vasudevram <vasudevram at gmail.com> wrote:
> Can anyone - maybe one of the Python language core team, or someone with knowledge of the internals of Python - can explain why this code works, and whether the different occurrences of the name x in the expression, are in different scopes or not? :
>
> x = [[1,2], [3,4], [5,6]]
>     [x for x in x for x in x]

I'll give this +1 for playfulness, and -2 for lack of clarity.

I hope no one thinks this sort of thing is good to do in real-life code.


From greg.ewing at canterbury.ac.nz  Thu Mar 27 19:45:57 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Fri, 28 Mar 2014 12:45:57 +1300
Subject: unicode as valid naming symbols
In-Reply-To: <lh1i4f$rrp$1@speranza.aioe.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <4e0ffd3a-8c50-4726-b214-f7b44d4e01ae@googlegroups.com>
 <lh1i4f$rrp$1@speranza.aioe.org>
Message-ID: <bpjrhjFb2hsU1@mid.individual.net>

Mark H Harris wrote:
>> Good ol infix -- x+y..
>> prefix (with paren) -- foo(x)
>> prefix without  -- ? x
>> In case you thought alphanumerics had parens --  sin x
>> Then theres postfix   -- n!
>> Inside fix   -- nCr (Or if you prefer ?C? ??)
>> And outside fix -- mod -- |x|

And mismatched delimiters:

    [5, 7)

    |x>

-- 
Greg


From ethan at stoneleaf.us  Thu Mar 27 20:04:00 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Thu, 27 Mar 2014 17:04:00 -0700
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <lh2444$u2k$1@ger.gmane.org>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
 <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
 <lh2444$u2k$1@ger.gmane.org>
Message-ID: <5334BC70.8000905@stoneleaf.us>

On 03/27/2014 02:10 PM, Terry Reedy wrote:
> On 3/27/2014 7:42 AM, Chris Angelico wrote:
>
>> In any case... what I'd suggest would be opening a tracker issue, or
>> discussing this on python-ideas, and seeing what core devs think of
>> the matter. I think that, on balance, it's probably better to show the
>> whole thing with the same sign; but should it be:
>
> Before doing so, I suggest looking for the design discussion either on the tracker or in python-ideas or py-dev lists.
>
>>--> str(datetime.timedelta(-1, -1))
>> '-1 day, 00:00:01'
>>
>> or should the hyphen be repeated:
>>
>>--> str(datetime.timedelta(-1, -1))
>> '-1 day, -00:00:01'
>
> '-(1 day, 00:00:01)' should be unambiguous.

Or change the comma to an and:

'-1 day and 00:00:01'

--
~Ethan~


From roy at panix.com  Thu Mar 27 20:29:17 2014
From: roy at panix.com (Roy Smith)
Date: Thu, 27 Mar 2014 20:29:17 -0400
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-E6F0E7.20291727032014@news.panix.com>

In article <5334b747$0$29994$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> On Thu, 27 Mar 2014 08:52:24 -0400, Roy Smith wrote:
> 
> > In article <mailman.8613.1395917059.18130.python-list at python.org>,
> >  Chris Angelico <rosuav at gmail.com> wrote:
> >> It's not "equally braindead", it follows a simple and logical rule:
> >> Only the day portion is negative.
> > 
> > Simple and logical, yes.  But also entirely braindead.
> 
> Do you think it is "braindead" for __str__ to return something which 
> follows the internal representation of the object?

Yes.  The whole idea of OOD is to decouple internal representation from 
external behavior.

> > Give ma a real-life situation where you would want such behavior.
> 
> Easy -- I'm debugging timedelta routines, and I want to easily see that 
> the timedeltas calculated match what I expect them to be when I print 
> them. The quickest, easiest and simplest way is for str(timedelta) to 
> follow the internal representation.

That's what __repr__() is for.
 
> Oh look, that's exactly what the docs say:
> 
> "String representations of timedelta objects are normalized similarly to 
> their internal representation. This leads to somewhat unusual results for 
> negative timedeltas."

Yes, I know that's what the docs say.  That's why it's not an 
implementation bug.  It's a design bug :-)


From steve+comp.lang.python at pearwood.info  Thu Mar 27 20:34:23 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 28 Mar 2014 00:34:23 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
Message-ID: <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 27 Mar 2014 10:44:49 -0500, Mark H Harris wrote:

> On 3/26/14 1:35 AM, alex23 wrote:
>> On 25/03/2014 12:39 PM, Mark H Harris wrote:
>>> my version semantically is "how it is perceived" by the user
>>
>> Could you please stop claiming to have insight into the comprehension
>> of anyone other than yourself? Hasty generalisations don't help your
>> argument.
> 
> hi alex23,  please don't be silly.
> 
> Who is being hasty?  How do you know its a generalization?

When you claim to speak for "the user" (your words, not mine), as in the 
quote above, what else could it be than a generalisation? Unless you 
believe that there actually is *one single person* using Python, you are 
generalising the millions of users (note plural) into one idealised user 
who speaks for all.


> My comments here are not in the least hasty, nor are they
> generalizations. 

Of course they are. Unless you claim that there is literally only one 
person using Python -- which is obviously absurd -- you are making a 
statement about the huge variety of Python users as if they all agreed on 
this matter. That is a generalisation.

It might even be a valid generalisation, although I doubt it. You have a 
pattern of discounting or rejecting the needs and desires of *most* 
programmers in favour of what you perceive as the needs and wants of a 
*tiny* subset of inexperienced programmers -- those who aren't interested 
in becoming experienced, but want to continue programming -- as if they 
were all users of Python. They are not. Not even close. And they are 
certainly not the people who keep Python alive and well -- if anything, 
they are users in the sense that they *use* Python and the resources of 
the Python community, but they will never, ever give back.

Maybe your generalisation about *users* is more apt than either of us 
realised.

Your generalisation doesn't even apply to *all* inexperienced beginners. 
If you wanted to turn Python into a teaching language, that would be an 
interesting proposal, but you don't. Consider your recent comments that ? 
should be allowed as an identifier, and that it should be a built-in. 
Screw the people who know and understand Unicode rules, your suggestion 
would break their expectations, but those users don't count for you. 
Presumably, anyone who knows Unicode must be an expert, and experts don't 
matter to you. Screw the people who have no interest in mathematics, and 
wouldn't know a square root symbol from a kick to the head. Those users 
don't count either. As for enormous number of users who will have 
difficulty typing ? in their source code, they certainly don't count! 
It's good enough that *you* have a solution to that problem, you can type 
alt-v, and anyone who can't simply doesn't matter.


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ben+python at benfinney.id.au  Thu Mar 27 20:43:17 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Fri, 28 Mar 2014 11:43:17 +1100
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
Message-ID: <8538i3p2ze.fsf@benfinney.id.au>

Roy Smith <roy at panix.com> writes:

> In article <5334b747$0$29994$c3e8da3$5496439d at news.astraweb.com>,
>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>
> > On Thu, 27 Mar 2014 08:52:24 -0400, Roy Smith wrote:
> > > Give ma a real-life situation where you would want such behavior
> > > [the ?datetime.timedelta.__str__? method returning a string
> > > showing some portions negative and others positive].
> > 
> > Easy -- I'm debugging timedelta routines, and I want to easily see
> > that the timedeltas calculated match what I expect them to be when I
> > print them. The quickest, easiest and simplest way is for
> > str(timedelta) to follow the internal representation.
>
> That's what __repr__() is for.

Indeed, that is why Python's data model defines separate ?__str__? and
?__repr__? methods.

    object.__repr__(self)

    [?] If at all possible, this should look like a valid Python
    expression that could be used to recreate an object with the same
    value (given an appropriate environment). If this is not possible, a
    string of the form <...some useful description...> should be
    returned.

    <URL:http://docs.python.org/3/reference/datamodel.html#object.__repr__>

    object.__str__(self)

    [?] compute the ?informal? or nicely printable string representation
    of an object. [?] a more convenient or concise representation can be
    used.

    <URL:http://docs.python.org/3/reference/datamodel.html#object.__str__>

If you're a programmer wanting to know about the internal representation
of an object, call its ?__repr__? method (by calling ?repr(foo)?).

If you're wanting to see a string representation that follows the
*semantics* of the object, call its ?__str__? method (by calling
?str(foo)?).

If the ?__str__? method follows the internal representation at the
expense of the user's conceptual model, that's terrible (which I think
is what Roy means by ?braindead?).

I wouldn't go as far as that insult, because it could be mere omission:

    The default implementation [of ?__str__?] defined by the built-in
    type object calls object.__repr__().

So, where ?str(foo)? is returning an unhelpful representation that
follows the implementation, it could simply be that there is no
?__str__? defined for that type.

> > Oh look, that's exactly what the docs say:
> > 
> > "String representations of timedelta objects are normalized
> > similarly to their internal representation. This leads to somewhat
> > unusual results for negative timedeltas."
>
> Yes, I know that's what the docs say.  That's why it's not an 
> implementation bug.  It's a design bug :-)

One which to some extent violates the defined data model for Python
objects, and hence should be fixed.

-- 
 \      ?I don't know half of you half as well as I should like, and I |
  `\   like less than half of you half as well as you deserve.? ?Bilbo |
_o__)                                                          Baggins |
Ben Finney



From tjreedy at udel.edu  Thu Mar 27 21:32:14 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 27 Mar 2014 21:32:14 -0400
Subject: meta language to define forms
In-Reply-To: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
References: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
Message-ID: <lh2jes$8uv$1@ger.gmane.org>

On 3/27/2014 4:56 PM, Sells, Fred wrote:
> I'm trying to use python classes and members to define complex data
> entry forms as a meta language
>
> The idea is to use a nice clean syntax like Python to define form
> content, then render it as HTML but only as a review tool for users,
> The actual rendering would go into a database to let a vendor's tool
> generate the form in a totally non-standard syntax that's really
> clunky.
>
> I don't have a lot of time or management support to do something
> elegant like XML and then parse it, I'm thinking more like
>
> Class  FyFormNumber001(GeneralForm):
>  Section1 = Section(title="Enter Patient Vital Signs")
 >    Question1 = NumberQuestion(title="Enter pulse rate", format="%d3")
 >    Question2 = Dropdown(title="Enter current> status")
 >    Question2.choices = [ (1, "Alive and Kicking"), (2,
>  "Comatose"), (3, "Dead"), ...]
>
> Of course this is not quite legal python and I have a lot of
> flexibility in my "meta" language.  The basic model is that a single
> file would define a form which would have one or more sections,  each
> section would have one or more questions of various types (i.e.
> checkbox, radio button, text, etc).  Sections cannot be nested.
>
> I don't have to have a perfect layout, just close enough to get the
> end users to focus on what they are asking for before we generate the
> actual code.  I tried an HTML WYSIWYG editor but that was too slow
> and I lost information that I need to retain when the actual form is
> generated.
>
> The biggest problem (to me) is that I have to maintain the order;
> i.e. the order in which they are coded should be the order in which
> they are displayed.
>
> I'm looking to do about 200 forms, so it is reasonable to invest some
> time up front to make the process work; meanwhile management wants
> results yesterday, so I have a trade-off to make.
>
> Is there anything out there that would be close or do you have any
> suggestions.

Have you searched the python-list archives? PyPI? or the web?
There was a thread on this topic perhaps a month ago but I barely 
followed it.


-- 
Terry Jan Reedy



From tanmay.kansara at gmail.com  Thu Mar 27 21:34:02 2014
From: tanmay.kansara at gmail.com (tanmay.kansara at gmail.com)
Date: Thu, 27 Mar 2014 18:34:02 -0700 (PDT)
Subject: implementing download using a url call
Message-ID: <d58f6cea-c290-41f6-8f06-47c317243a8f@googlegroups.com>

Hey Guys,

here is what I am trying to solve. 

I have a URL - somesite.com/server/pattern.x?some_more_stuff

This URl is out there as an href tag on users website. Is there a way in which I can serve a file(not from my server) while ensuring that the users remain on the third party website. I am currently using this :

myfile = "http://download.someothersite.com/somefile.exe"
    
    meta_tag = "<html><head><meta http-equiv='Refresh' Content='1;URL=%s'></head></html>" % myfile
    return HttpResponse(meta_tag, content_type='force-download')

The above works, however the user gets redirected to a blank page. Would downloading and serving the file from my server be a better option? If so, some pointers please.

Do let me know what would be an elegant solution. The file sizes should be about 500kb(stub files).

Thanks


From davea at davea.name  Thu Mar 27 21:44:51 2014
From: davea at davea.name (Dave Angel)
Date: Thu, 27 Mar 2014 21:44:51 -0400 (EDT)
Subject: Python language hack for C-style programmers [DO NOT USE!] :-)
References: <20140327110856.14991bb0@bigbox.christie.dr>
 <CAPTjJmoSEiBEO9fXfwM7mGywty+dT8erBqeu2mpyrxAf12udcw@mail.gmail.com>
Message-ID: <lh2jsg$cqu$1@ger.gmane.org>

 Chris Angelico <rosuav at gmail.com> Wrote in message:
> On Fri, Mar 28, 2014 at 3:08 AM, Tim Chase
> <python.list at tim.thechases.com> wrote:
>> Multiple times, I've seen someone want something like what C-style
>> languages offer where assignment is done in a test, something like
>>
>>   if (m = re.match(some_string)):
>>     do_something(m)
> 
> If you want a language where you can do this sort of thing, but the
> semantics are like Python's (first-class complex objects, garbage
> collection, references instead of pointers, pass-by-object, etc),
> check out Pike. Its syntax is very much C's, or C++'s or Java's if you
> prefer, but it functions very much the way Python does. You can even -
> and you can't do this in C or, to my knowledge, C++ - declare a
> variable inside an if, which is valid only in the body of that if:
> 
> if (array m = Regexp.split2(some_pattern, some_string))
>     do_something(m);
> 

I don't know for certain about if, but you can declare (in C++) a
 new variable in for, which is a superset of if. Scope ends when
 the for does.



-- 
DaveA



From davea at davea.name  Thu Mar 27 21:47:48 2014
From: davea at davea.name (Dave Angel)
Date: Thu, 27 Mar 2014 21:47:48 -0400 (EDT)
Subject: SSL: DECRYPTION_FAILED_OR_BAD_RECORD_MAC
References: <94cfb444-8c5d-4b2c-b08c-29170991d02b@googlegroups.com>
Message-ID: <lh2k1v$cqu$2@ger.gmane.org>

 tade.ankur at gmail.com Wrote in message:
> 
> hei , 
> 
> I am a newcome to Python. 
> 
> I am trying to create a python script which will connect to an SSL URL and using the HEAD request will get the status of URL. 
> 
> For one the link I am getting following error
> 
> [SSL: DECRYPTION_FAILED_OR_BAD_RECORD_MAC] decryption failed or bad record mac (_ssl.c:589)

And why do you omit the rest of the error?  

> 

> 


-- 
DaveA



From tjreedy at udel.edu  Thu Mar 27 21:46:25 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 27 Mar 2014 21:46:25 -0400
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <lh2444$u2k$1@ger.gmane.org>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
 <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
 <lh2444$u2k$1@ger.gmane.org>
Message-ID: <lh2k9f$gpt$1@ger.gmane.org>

On 3/27/2014 5:10 PM, Terry Reedy wrote:
> On 3/27/2014 7:42 AM, Chris Angelico wrote:
>
>> In any case... what I'd suggest would be opening a tracker issue, or
>> discussing this on python-ideas, and seeing what core devs think of
>> the matter. I think that, on balance, it's probably better to show the
>> whole thing with the same sign; but should it be:
>
> Before doing so, I suggest looking for the design discussion either on
> the tracker or in python-ideas or py-dev lists.

And skip the troll word 'braindead'.

Terry Jan Reedy



From rosuav at gmail.com  Thu Mar 27 21:52:04 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 12:52:04 +1100
Subject: Python language hack for C-style programmers [DO NOT USE!] :-)
In-Reply-To: <lh2jsg$cqu$1@ger.gmane.org>
References: <20140327110856.14991bb0@bigbox.christie.dr>
 <CAPTjJmoSEiBEO9fXfwM7mGywty+dT8erBqeu2mpyrxAf12udcw@mail.gmail.com>
 <lh2jsg$cqu$1@ger.gmane.org>
Message-ID: <CAPTjJmoU-Aa_Y2DDHzCyzMNUfNnuV2i2gsHWZP3gKBhzrXjLzw@mail.gmail.com>

On Fri, Mar 28, 2014 at 12:44 PM, Dave Angel <davea at davea.name> wrote:
>> if (array m = Regexp.split2(some_pattern, some_string))
>>     do_something(m);
>>
>
> I don't know for certain about if, but you can declare (in C++) a
>  new variable in for, which is a superset of if. Scope ends when
>  the for does.

Yeah, but only a for, AFAIK. Not an if or a while.

ChrisA


From roy at panix.com  Thu Mar 27 21:59:55 2014
From: roy at panix.com (Roy Smith)
Date: Thu, 27 Mar 2014 21:59:55 -0400
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
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 <lh2444$u2k$1@ger.gmane.org>
 <mailman.8647.1395971209.18130.python-list@python.org>
Message-ID: <roy-0ADBDD.21595527032014@news.panix.com>

In article <mailman.8647.1395971209.18130.python-list at python.org>,
 Terry Reedy <tjreedy at udel.edu> wrote:

> On 3/27/2014 5:10 PM, Terry Reedy wrote:
> > On 3/27/2014 7:42 AM, Chris Angelico wrote:
> >
> >> In any case... what I'd suggest would be opening a tracker issue, or
> >> discussing this on python-ideas, and seeing what core devs think of
> >> the matter. I think that, on balance, it's probably better to show the
> >> whole thing with the same sign; but should it be:
> >
> > Before doing so, I suggest looking for the design discussion either on
> > the tracker or in python-ideas or py-dev lists.
> 
> And skip the troll word 'braindead'.
> 
> Terry Jan Reedy

I apologize for my poor choice of vocabulary.


From rosuav at gmail.com  Thu Mar 27 22:24:15 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 13:24:15 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <5334A2B1.20006@gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
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Message-ID: <CAPTjJmp2E6rci2v7_v-+W6DbBnw8Lbx0Ve67W2Yt00VBjaibgA@mail.gmail.com>

On Fri, Mar 28, 2014 at 9:14 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> Your question has a somewhat false premise. They *really do* want to learn
> them, and they are frustrated with the time and attention it takes. The
> argument is also from analogy, which in this case is almost similar but not
> quite.
>
> Now, there is no royal road to geometry, opera, the violin, and the piano
> (I'm a pianist, and flutist--and an amateur composer). All of these fine
> arts take time, there is just no getting around it.

How many hours of practice have you put into musical study? The usual
estimate is ten thousand hours to achieve mastery. If you're an
amateur composer, you've probably put in rather a lot of hours. (I am
one also, and I'm pretty sure I've put in rather a lot more than 10K
hours in various musical fields.) But if you just want to sing hymns
in church, you don't need *or want* to put in that much practice. Why
should that sort of person want to learn/master opera?

I used opera as an example because I'm about to dive into another one
- this Tuesday is bump-in (getting all our scenery into the theatre),
and we open before a real audience on April 5th. [1] In that
production are a number of really REALLY awesome people (Ron Pidcock,
Jenny Wakefield, Lydia Kovesi, Andrea Tappe...) who've put in huge
numbers of hours to master the singing, dancing, etc required for the
roles. Me? I'm able to sing, but I don't have the time (or the money)
to get *that* good, so I don't audition for roles. I'm content to work
lighting instead.

Conversely, I'm a master of networking. I've put in plenty of hours to
achieve mastery, and continue to do so. One of our sopranos was having
trouble with her home network, and I swung by and gave her a hand. She
doesn't want or need to understand what's going on, yet she uses and
appreciates her wireless network. She *really does not* want to learn
networking, or programming, just as I do not want to learn operatic
singing, or how to build a death ray. Python can come in handy for
her, but she is NOT the "normal user" for Python - and yet she fits
into your description, below.

> People want to use their computer. They want to solve problems with it...
> and frankly, they would like to know how to program it, if there where some
> royal road, or fast track, or short and easy tutorial. I know lots of people
> that will sit down and try (with a cup of Java) and hack it out if they have
> a good short book.

There might be a short and easy tutorial "Python for people who
already know Pike" (except that there won't be much call for it).
There could possibly be "Python for mathematicians", because maths
requires a similar vigor. There might even be "Python for brain
surgeons". But there won't be "Python for people who know nothing" as
a simple tutorial. It takes skill and mastery to become a programmer,
and that doesn't come from nowhere. Transferring that skill from
another area is easier than conjuring it (and easier still if the two
areas are similar), but if someone has a similar skill already, s/he's
probably already a programmer, and so isn't part of your description.

Most people want to *use* a computer, and most certainly do *not* want
to *program* it. I know this from personal experience; plenty of
people will use electronica that they can't fiddle with - just look at
the popularity of the iphone. There might well be an app for that, but
if there isn't, well, you're going to need to go through a lot of
hoops to create it. There's no way a typical iphone user can program
his/her phone.

> Just look on the list:  Fred Sells meta language request.  He proves my
> point entirely.  I have not responded yet... thought I would wait a bit...
> but look what he is after.  Go read it.

I've read it (although not Terry's response, yet). He wants to create
a DSL. I didn't respond because I know someone else will do so better
(also, it was 8AM and I'd been up most of the night learning about
systemd - making the jump now that Debian's settling on it, so it's
time to port my Upstart jobs and knowledge), but my guess would be
that he's not really looking for a *programming* language, but a *page
description* language. Something in the same field as HTML, not
Python.

> But, I don't disagree with you Chris, and I have myself some of the same
> concerns really. I'm finding the path harder than I thought it would be.
> Well, its hard enough just getting other people who are experts to buy into
> it.  Its going to be an uphill climb, for sure.

Programming forces you to understand programming. Even if you just use
Python as a super-calculator (which, incidentally, I often do), you're
still going to end up running into edge cases that force you to
comprehend what you're doing:

>>> 1e16+3-1e16
4.0

Common sense says it ought to be 3.0, but it ain't. IEEE floating
point explains why this happens, but that's getting technical.

If you don't want to write code, get a calculator. If you want to
write code, learn at least something of programming, and understand
that Python's syntax is not aimed at the person who knows nothing. A
car's engine usually isn't tuned for 10km/h running; you have to get
up a bit of speed before it becomes more efficient. Why is it so wrong
for Python to expect the same?

ChrisA

[1] http://gilbertandsullivan.org.au/ - come see us if you're in Melbourne!


From tjreedy at udel.edu  Thu Mar 27 22:24:45 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 27 Mar 2014 22:24:45 -0400
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <roy-0ADBDD.21595527032014@news.panix.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
 <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
 <lh2444$u2k$1@ger.gmane.org>
 <mailman.8647.1395971209.18130.python-list@python.org>
 <roy-0ADBDD.21595527032014@news.panix.com>
Message-ID: <lh2mhb$71t$1@ger.gmane.org>

On 3/27/2014 9:59 PM, Roy Smith wrote:
> In article <mailman.8647.1395971209.18130.python-list at python.org>,
>   Terry Reedy <tjreedy at udel.edu> wrote:
>
>> On 3/27/2014 5:10 PM, Terry Reedy wrote:
>>> On 3/27/2014 7:42 AM, Chris Angelico wrote:
>>>
>>>> In any case... what I'd suggest would be opening a tracker issue, or
>>>> discussing this on python-ideas, and seeing what core devs think of
>>>> the matter. I think that, on balance, it's probably better to show the
>>>> whole thing with the same sign; but should it be:
>>>
>>> Before doing so, I suggest looking for the design discussion either on
>>> the tracker or in python-ideas or py-dev lists.
>>
>> And skip the troll word 'braindead'.

> I apologize for my poor choice of vocabulary.

I actually meant if you post on the tracker or python-ideas. There is a 
little more leeway here. But as you maybe noticed. even here a trollish 
word can divert discussion from you main point.

Back to your main point: the current output looks strange to me also. 
But I did not follow the datetime development discussion. I do know that 
the people responsible are not normally braindead ;-).

-- 
Terry Jan Reedy



From rosuav at gmail.com  Thu Mar 27 22:26:51 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 13:26:51 +1100
Subject: implementing download using a url call
In-Reply-To: <d58f6cea-c290-41f6-8f06-47c317243a8f@googlegroups.com>
References: <d58f6cea-c290-41f6-8f06-47c317243a8f@googlegroups.com>
Message-ID: <CAPTjJmrnsPXJ05-3b81BCSY4eHXK_q27M_s33Az9uStXy1iWQQ@mail.gmail.com>

On Fri, Mar 28, 2014 at 12:34 PM,  <tanmay.kansara at gmail.com> wrote:
> Hey Guys,
>
> here is what I am trying to solve.
>
> I have a URL - somesite.com/server/pattern.x?some_more_stuff
>
> This URl is out there as an href tag on users website. Is there a way in which I can serve a file(not from my server) while ensuring that the users remain on the third party website. I am currently using this :
>
> myfile = "http://download.someothersite.com/somefile.exe"
>
>     meta_tag = "<html><head><meta http-equiv='Refresh' Content='1;URL=%s'></head></html>" % myfile
>     return HttpResponse(meta_tag, content_type='force-download')
>
> The above works, however the user gets redirected to a blank page. Would downloading and serving the file from my server be a better option? If so, some pointers please.

So what you want is for the user to go to a page which both downloads
a file *and* displays content, is that it?

This is fairly common on the web today; have a look at how places like
Sourceforge do it.

ChrisA


From rustompmody at gmail.com  Thu Mar 27 22:46:07 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 27 Mar 2014 19:46:07 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8650.1395973465.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
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Message-ID: <76663d88-45d7-49f1-a2a4-b35120e7f963@googlegroups.com>

On Friday, March 28, 2014 3:44:09 AM UTC+5:30, Mark H. Harris wrote:
> On 3/27/14 4:42 PM, Chris Angelico wrote:
> > And this is the bit where, I think, we disagree. I think that
> > programming is for programmers, in the same way that music is for
> > musicians and the giving of legal advice is for lawyers. Yes, there
> > are armchair lawyers, and plenty of people can pick up a hymn book and
> > sing;

As for programming its just too much in-our-face (to most of us
reading this at least) to discuss it from the pov of 'the* layman'
for the same reason that if I try to show you something and stick it
? inch from your nose, you wont be able to see it.

Your other examples fire quite differently than you (perhaps) realize

As for laws, I am reminded of the Tao te Ching:

Therefore the Master says:
I let go of the law, and people become honest.
I let go of economics, and people become prosperous.
I let go of religion, and people become serene.
I let go of all desire for the common good, and the good becomes common as grass. 
http://acc6.its.brooklyn.cuny.edu/~phalsall/texts/taote-v3.html#57

As for music I find (as Mark does) that technology allows for a 
10-fold leap in learning:
When I learnt the piano, 10 years to perform anything reasonably
and 10 months to make head-or-tail of staff notation were fair estimates.

Today, spend 10 days browsing your favourite genre at
http://musescore.com/ with a little guidance and staff notation stops being difficult.
A couple of weeks more and one and start entering music into the computer (or phone)

> ------------------------------------
> > but laws and operas aren't designed with them in mind. Why
> > should programming languages be designed for the people who don't want
> > to learn them?

> Actually we agree quite a bit on this--I agree with everything above the 
> line----- and some of the sentiment with everything below the line.

> Your question has a somewhat false premise. They *really do* want to 
> learn them, and they are frustrated with the time and attention it 
> takes. The argument is also from analogy, which in this case is almost 
> similar but not quite.

Well if you see http://cultureandempire.com/cande.html there is this
interesting insight:

> Moore?s Law isn?t a mythical beast that magically materialized in 1965
> and threatens to unpredictably vanish at any moment. In fact, it?s
> part of a broader ancient mechanism that has no intention of
> stopping. This mechanism, which I call cost gravity, pulls down the
> price of technology by about half every two years.

Add to that the fact that cost=money ultimately comes from money=effort
eg currencies like http://en.wikipedia.org/wiki/Ithaca_Hours
(maybe even dolour ? dollar though thats not the official etymology)
and its clear that there is a ripple effect of technology breaking down
old castles. Pleasant to the* layman, unpleasant to those professionals whose 
fiefdoms are threatened.

> A car's engine usually isn't tuned for 10km/h running; you have to get
> up a bit of speed before it becomes more efficient. Why is it so wrong
> for Python to expect the same? 

Lets (temporarily) invert your example:
100 years ago, cobbled streets and horse-carriages were not meant for 100 kmph
speeds. Today's roads are.
Likewise technology: Like the natural speed of roads has changed, the natural
accessibility of technology has also.
A big part of python's success was that 20 years ago it worked out way more
accessible than C. This peaked around 10 years ago.  Nowadays I am not so sure 
what its direction is...

------------
* And I'll leave it to Steven to cudgel the 'the' <wink>


From rosuav at gmail.com  Thu Mar 27 23:02:08 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 14:02:08 +1100
Subject: meta language to define forms
In-Reply-To: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
References: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
Message-ID: <CAPTjJmo+C3QR+iBzsA6jW_NfcPCmXCJkQBLGhQjngLPTzdTi4Q@mail.gmail.com>

On Fri, Mar 28, 2014 at 7:56 AM, Sells, Fred
<fred.sells at adventistcare.org> wrote:
> I don't have a lot of time or management support to do something elegant like XML and then parse it, I'm thinking more like
>
> Class  FyFormNumber001(GeneralForm):
>         Section1 = Section(title="Enter Patient Vital Signs")
>                 Question1 = NumberQuestion(title="Enter pulse rate", format="%d3")
>                 Question2 = Dropdown(title="Enter current status")
>                 Question2.choices = [ (1, "Alive and Kicking"), (2, "Comatose"), (3, "Dead"), ...]

Rule of Python: XML is not the answer. XML is the question, and "NO!"
is the answer :)

Your syntax there looks reasonable already. I'd recommend you make it
a flat data file, though, don't try to make it a programming language
- unless you actively need it to be one. Here are a couple of ways you
could format this. Any would be fairly easy to code a parser for.

(I'm guessing your format there should probably be "%3d", if you mean
printf notation. But I'll keep your "%d3" example in the below.)

1) Using indentation for nesting, and a "command, space, args" model:

GeneralForm FyFormNumber001
        Section "Enter Patient Vital Signs"
                NumberQuestion "Enter pulse rate" format="%d3"
                Dropdown "Enter current status"
                        Choice 1 "Alive and Kicking"
                        Choice 2 "Comatose"
                        Choice 3 "Dead"
                        ...

This would be parsed with an algorithm like this:
* Maintain an indentation stack, which starts with a top level entry.
* Read one line. Parse it into three parts: leading indentation, command, args.
* Remove from the indentation stack everything equal to or greater
than this line's indent.
* Send the command to the last entry on your indentation stack, with its args.
* Capture the result of that command and put it on the indentation stack.
* Iterate until end of file.

You'd then have a top-level object that understands a "GeneralForm"
command and returns a form object; the form object understands the
"Section" command and returns a section object; the "Dropdown" object
understands "Choice"; and so on.


2) Rendering the whole thing as JSON:

{"type": "GeneralForm", "FormName": "FyFormNumber001", "children": [
        {"type":"Section", "Title": "Enter Patient Vital Signs", "children": [
                {"type": "NumberQuestion", "title":"Enter pulse rate",
"format":"%d3"},
                {"type": "Dropdown", "title":"Enter current status",
"children": [
                        {"type":"Choice", "value":1, "name":"Alive and
Kicking"},
                        {"type":"Choice", "value":2, "name":"Comatose"},
                        {"type":"Choice", "value":3, "name":"Dead"},
                        ...
                ]}
        ]}
]}

This would be parsed by first converting the JSON into a tree of dicts
and lists, and then at each step, checking the type, and processing
its children. The bulk of the work could be done generically, and it's
easy to add attributes to anything. The cost, though, is that you need
to be a bit verbose about the common attributes.


3) Actual Python code:

FyFormNumber001 = GeneralForm(
        Sections = [Section("Enter Patient Vital Signs", Questions=[
                NumberQuestion("Enter pulse rate", format="%d3"),
                Dropdown("Enter current status",
                        choices=[ (1, "Alive and Kicking"), (2,
"Comatose"), (3, "Dead"), ...]
                ),
        ]),
])

This would be parsed by creating functions or classes named
GeneralForm, Section, NumberQuestion, etc, and having them handle
positional arguments for the obvious things, and keyword args for the
less obvious. (I may have misjudged which is which, but you should
make a design decision about that.) I've used keyword args for
everything that's a list, but that could be done differently if you
choose.


4) Actual Pike code.

This came up in the thread Terry's referring to. Its primary advantage
was that it *already existed* (we were talking about GTK2), where all
the above options do require code. It would look something like this:

object FyFormNumber001=GeneralForm()
        ->add(Section("Enter Patient Vital Signs")
                ->add(NumberQuestion("Enter pulse rate", "%d3"))
                ->add(Dropdown("Enter current status")
                        ->add_choice(1, "Alive and Kicking")
                        ->add_choice(2, "Comatose")
                        ->add_choice(3, "Dead")
                        ...
                )
        )
;

I don't recommend this above the options listed above; but I'd say
it's at least 95% as good as the others, and if you find a way to get
something that looks like this with practically zero effort, I would
strongly advise going with it. (Another advantage of the Pike GTK2
system is that you often want to manipulate the objects post-creation
and pre-insertion into the tree. I don't think you need that
flexibility here, so again, this one is just for comparison.)

If you can, try to go for the first option. It's clean, and it's not
terribly hard to parse. Failing that, the third option isn't too bad,
but I'd advise against going with JSON; one misplaced comma or bracket
and you have a tough debugging problem to solve. You might get that
problem with the Python-code version too, but you have a bit of a
better chance at a readable traceback there.

ChrisA


From rosuav at gmail.com  Thu Mar 27 23:03:15 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 14:03:15 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <lh2mhb$71t$1@ger.gmane.org>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <lh11s1$kj3$1@news.albasani.net>
 <CAPTjJmqbD_QYU4P5eQLmdnHcHFzr2w0HfF6JuEuRgMbU2oWx=g@mail.gmail.com>
 <lh2444$u2k$1@ger.gmane.org>
 <mailman.8647.1395971209.18130.python-list@python.org>
 <roy-0ADBDD.21595527032014@news.panix.com>
 <lh2mhb$71t$1@ger.gmane.org>
Message-ID: <CAPTjJmo+OC0aQVCvccqNYW_DZDpTnGbPvYh02e_okGAe-JyBDQ@mail.gmail.com>

On Fri, Mar 28, 2014 at 1:24 PM, Terry Reedy <tjreedy at udel.edu> wrote:
> I do know that the people responsible are not normally braindead ;-).

Yeah, anyone who develops Python is clearly abnormally braindead...

*dives for cover*

ChrisA


From rosuav at gmail.com  Thu Mar 27 23:06:26 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 14:06:26 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <76663d88-45d7-49f1-a2a4-b35120e7f963@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
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 <lh1k4e$1il$1@speranza.aioe.org>
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 <lh236d$bcv$1@speranza.aioe.org>
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 <5334A2B1.20006@gmail.com>
 <mailman.8650.1395973465.18130.python-list@python.org>
 <76663d88-45d7-49f1-a2a4-b35120e7f963@googlegroups.com>
Message-ID: <CAPTjJmpGoPLDLS=XX65M9QK1QThkmxYJnfyM9A9OpM8PEWAvqw@mail.gmail.com>

On Fri, Mar 28, 2014 at 1:46 PM, Rustom Mody <rustompmody at gmail.com> wrote:
>> Moore?s Law isn?t a mythical beast that magically materialized in 1965
>> and threatens to unpredictably vanish at any moment. In fact, it?s
>> part of a broader ancient mechanism that has no intention of
>> stopping. This mechanism, which I call cost gravity, pulls down the
>> price of technology by about half every two years.
>
> Add to that the fact that cost=money ultimately comes from money=effort
> eg currencies like http://en.wikipedia.org/wiki/Ithaca_Hours
> (maybe even dolour ? dollar though thats not the official etymology)
> and its clear that there is a ripple effect of technology breaking down
> old castles. Pleasant to the* layman, unpleasant to those professionals whose
> fiefdoms are threatened.

The price of technology to the end user, yes. Anyone can go out and
buy a computer that's powerful enough to do everything the typical
person needs, and it's cheap enough to fit inside the typical person's
budget. (Compare early IBM estimates of maybe half a dozen computer
sales worldwide.) That has nothing to do with whether or not that
person can create that computer. Same goes for software.

ChrisA


From roy at panix.com  Thu Mar 27 23:13:21 2014
From: roy at panix.com (Roy Smith)
Date: Thu, 27 Mar 2014 23:13:21 -0400
Subject: meta language to define forms
References: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
 <mailman.8653.1395975737.18130.python-list@python.org>
Message-ID: <roy-A58360.23132127032014@news.panix.com>

In article <mailman.8653.1395975737.18130.python-list at python.org>,
 Chris Angelico <rosuav at gmail.com> wrote:

> On Fri, Mar 28, 2014 at 7:56 AM, Sells, Fred
> <fred.sells at adventistcare.org> wrote:
> > I don't have a lot of time or management support to do something elegant 
> > like XML and then parse it, I'm thinking more like
> >
> > Class  FyFormNumber001(GeneralForm):
> >         Section1 = Section(title="Enter Patient Vital Signs")
> >                 Question1 = NumberQuestion(title="Enter pulse rate", 
> >                 format="%d3")
> >                 Question2 = Dropdown(title="Enter current status")
> >                 Question2.choices = [ (1, "Alive and Kicking"), (2, 
> >                 "Comatose"), (3, "Dead"), ...]
> 
> Rule of Python: XML is not the answer. XML is the question, and "NO!"
> is the answer :)

The nice thing about that rule is that it ports easily to so many other 
programming languages.  Except possibly Java.  Java and XML seem to be 
made for each other.
 
> Your syntax there looks reasonable already. I'd recommend you make it
> a flat data file, though, don't try to make it a programming language
> - unless you actively need it to be one. Here are a couple of ways you
> could format this. Any would be fairly easy to code a parser for.

My first impression here is that YAML might work here.


From rustompmody at gmail.com  Thu Mar 27 23:20:34 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 27 Mar 2014 20:20:34 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8655.1395975990.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
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 <lh1k4e$1il$1@speranza.aioe.org>
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 <lh236d$bcv$1@speranza.aioe.org>
 <mailman.8637.1395956573.18130.python-list@python.org>
 <5334A2B1.20006@gmail.com>
 <mailman.8650.1395973465.18130.python-list@python.org>
 <76663d88-45d7-49f1-a2a4-b35120e7f963@googlegroups.com>
 <mailman.8655.1395975990.18130.python-list@python.org>
Message-ID: <69b6b39a-d76b-42ee-85bd-1084559cffc0@googlegroups.com>

On Friday, March 28, 2014 8:36:26 AM UTC+5:30, Chris Angelico wrote:
> On Fri, Mar 28, 2014 at 1:46 PM, Rustom Mody wrote:
> >> Moore?s Law isn?t a mythical beast that magically materialized in 1965
> >> and threatens to unpredictably vanish at any moment. In fact, it?s
> >> part of a broader ancient mechanism that has no intention of
> >> stopping. This mechanism, which I call cost gravity, pulls down the
> >> price of technology by about half every two years.
> > Add to that the fact that cost=money ultimately comes from money=effort
> > eg currencies like http://en.wikipedia.org/wiki/Ithaca_Hours
> > (maybe even dolour ? dollar though thats not the official etymology)
> > and its clear that there is a ripple effect of technology breaking down
> > old castles. Pleasant to the* layman, unpleasant to those professionals whose
> > fiefdoms are threatened.

> The price of technology to the end user, yes. Anyone can go out and
> buy a computer that's powerful enough to do everything the typical
> person needs, and it's cheap enough to fit inside the typical person's
> budget. (Compare early IBM estimates of maybe half a dozen computer
> sales worldwide.) That has nothing to do with whether or not that
> person can create that computer. Same goes for software.

This is the continuum fallacy: http://en.wikipedia.org/wiki/Continuum_fallacy

The Aunt Tillies (or your soprano)dont need to master networking as good as you 
do but they need to be better at it than they are.

To continue the example of music: I said that using something like
musescore a layman learns faster with a little guidance.  And heres
the catch -- most musicians who can guide in the traditional way are
frightened of technology.


From rosuav at gmail.com  Thu Mar 27 23:30:36 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 14:30:36 +1100
Subject: meta language to define forms
In-Reply-To: <roy-A58360.23132127032014@news.panix.com>
References: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
 <mailman.8653.1395975737.18130.python-list@python.org>
 <roy-A58360.23132127032014@news.panix.com>
Message-ID: <CAPTjJmp9sZ_tbvR-5aH_sfn03VAsMXJGFBCCk9dQE-L6MVKsWA@mail.gmail.com>

On Fri, Mar 28, 2014 at 2:13 PM, Roy Smith <roy at panix.com> wrote:
> In article <mailman.8653.1395975737.18130.python-list at python.org>,
>  Chris Angelico <rosuav at gmail.com> wrote:
>> Rule of Python: XML is not the answer. XML is the question, and "NO!"
>> is the answer :)
>
> The nice thing about that rule is that it ports easily to so many other
> programming languages.  Except possibly Java.  Java and XML seem to be
> made for each other.

The only times I have *ever* used XML, in my whole life, were when I
needed to communicate with some other end that stipulated XML. (Most
commonly XML payload in HTTP requests and responses, eg SOAP.) In most
of those cases, some simpler structure would have sufficed; and in a
number of them, XML is simply wrong for the job.

>> Your syntax there looks reasonable already. I'd recommend you make it
>> a flat data file, though, don't try to make it a programming language
>> - unless you actively need it to be one. Here are a couple of ways you
>> could format this. Any would be fairly easy to code a parser for.
>
> My first impression here is that YAML might work here.

Good point. Add it as a fifth option!

That section was already turning into a cardinal's weaponry statement.
I said "a couple" and ended up with four... now five. :)

ChrisA


From rustompmody at gmail.com  Thu Mar 27 23:44:39 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 27 Mar 2014 20:44:39 -0700 (PDT)
Subject: meta language to define forms
In-Reply-To: <roy-A58360.23132127032014@news.panix.com>
References: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
 <mailman.8653.1395975737.18130.python-list@python.org>
 <roy-A58360.23132127032014@news.panix.com>
Message-ID: <1c5b68d5-aab1-4ed6-8306-d4dc199d7e14@googlegroups.com>

On Friday, March 28, 2014 8:43:21 AM UTC+5:30, Roy Smith wrote:
>  Chris Angelico wrote:
> > Your syntax there looks reasonable already. I'd recommend you make it
> > a flat data file, though, don't try to make it a programming language
> > - unless you actively need it to be one. Here are a couple of ways you
> > could format this. Any would be fairly easy to code a parser for.

> My first impression here is that YAML might work here.

Was going to say yaml would be my first choice.

The only question here is whether to use the full-featured load or safe_load
which only allows builtin types.

In general load allowing calling of arbitrary code is a gaping security hole.
Here it may be the best choice... dunno

Personally I dont like mixing code and data.
Yeah lisp is fun and all that but when it starts getting at all serious
its a bloody mess.

[BTW I consider the windows registry cleaner than the linux /etc for 
the same reason]


From rosuav at gmail.com  Thu Mar 27 23:57:11 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 14:57:11 +1100
Subject: meta language to define forms
In-Reply-To: <1c5b68d5-aab1-4ed6-8306-d4dc199d7e14@googlegroups.com>
References: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
 <mailman.8653.1395975737.18130.python-list@python.org>
 <roy-A58360.23132127032014@news.panix.com>
 <1c5b68d5-aab1-4ed6-8306-d4dc199d7e14@googlegroups.com>
Message-ID: <CAPTjJmrpgUD1YMUBy++xEm+rscS4duV==hqTD32E1dv5whH_Kg@mail.gmail.com>

On Fri, Mar 28, 2014 at 2:44 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> [BTW I consider the windows registry cleaner than the linux /etc for
> the same reason]

And if I felt like trolling, I'd point out that there are a lot more
search engine hits for "windows registry cleaner" than "linux etc
cleaner". :)

ChrisA


From rustompmody at gmail.com  Fri Mar 28 00:19:46 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Thu, 27 Mar 2014 21:19:46 -0700 (PDT)
Subject: meta language to define forms
In-Reply-To: <mailman.8657.1395979034.18130.python-list@python.org>
References: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
 <mailman.8653.1395975737.18130.python-list@python.org>
 <roy-A58360.23132127032014@news.panix.com>
 <1c5b68d5-aab1-4ed6-8306-d4dc199d7e14@googlegroups.com>
 <mailman.8657.1395979034.18130.python-list@python.org>
Message-ID: <aee5fb71-3a32-4ada-84df-b631181ab962@googlegroups.com>

On Friday, March 28, 2014 9:27:11 AM UTC+5:30, Chris Angelico wrote:
> On Fri, Mar 28, 2014 at 2:44 PM, Rustom Mody  wrote:
> > [BTW I consider the windows registry cleaner than the linux /etc for
> > the same reason]

> And if I felt like trolling, I'd point out that there are a lot more
> search engine hits for "windows registry cleaner" than "linux etc
> cleaner". :)

Probably(!) follows from the fact that one is more possible than the other. 
Because of http://www.w3.org/2001/tag/doc/leastPower.html


From steve+comp.lang.python at pearwood.info  Fri Mar 28 00:45:37 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 28 Mar 2014 04:45:37 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <mailman.8623.1395936604.18130.python-list@python.org>
 <lh1k4e$1il$1@speranza.aioe.org>
 <mailman.8629.1395938933.18130.python-list@python.org>
 <lh236d$bcv$1@speranza.aioe.org>
 <mailman.8637.1395956573.18130.python-list@python.org>
 <mailman.8640.1395960068.18130.python-list@python.org>
Message-ID: <5334fe71$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 27 Mar 2014 17:14:09 -0500, Mark H Harris wrote:

> People want to use their computer. They want to solve problems with
> it... and frankly, they would like to know how to program it, if there
> where some royal road, or fast track, or short and easy tutorial. 

Most people want to program their computer in the same way they want to 
crawl around under their car changing the grease and oil. People want to 
use their computer, but they would prefer the computer already have an 
app to solve their problem. Some will program only if that is the only 
way to get the computer to do what they want. Most won't even do that.

If you ask the average Python-using biologist if they want to be a 
programmer, they will say something like "If I wanted to be a programmer, 
I would have done a comp sci degree. I want to be a biologist, and 
unfortunately having to program comes with the territory, like the other 
tedious jobs I have to do. I didn't do six years of college to wash test 
tubes or write code, but that's part of the job."


> I know
> lots of people that will sit down and try (with a cup of Java) and hack
> it out if they have a good short book.

There are seven billion people on planet Earth. If only one in ten 
thousand wants to program, that's still "lots of people".

But in any case, we're not talking about people who want to program and 
are willing to read a book to learn. We are talking about this subset of 
people who want to program without learning to program, and in particular 
your insistence that they count for more than programmers who want to 
learn to program.


[...]
> Just look on the list:  Fred Sells meta language request.  He proves my
> point entirely.

If I were Fred, I'd probably be insulted by that. He clearly knows 
programming jargon, and can use it correctly, and he is talking about 
being pressed for time and short on management support, which most 
programmers can relate to. What reason do you have to conclude from *one* 
post that he's one of your non-expert non-programmer programmers? Apart 
from wishful thinking, of course.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From wuwei23 at gmail.com  Fri Mar 28 02:37:18 2014
From: wuwei23 at gmail.com (alex23)
Date: Fri, 28 Mar 2014 16:37:18 +1000
Subject: meta language to define forms
In-Reply-To: <mailman.8632.1395953860.18130.python-list@python.org>
References: <mailman.8632.1395953860.18130.python-list@python.org>
Message-ID: <lh35b0$opb$1@dont-email.me>

On 28/03/2014 6:56 AM, Sells, Fred wrote:
> The idea is to use a nice clean syntax like Python to define form content, then render it as HTML but only as a review tool for users,  The actual rendering would go into a database to let a vendor's tool generate the form in a totally non-standard syntax that's really clunky.
>
> Class  FyFormNumber001(GeneralForm):
> 	Section1 = Section(title="Enter Patient Vital Signs")
> 		Question1 = NumberQuestion(title="Enter pulse rate", format="%d3")
> 		Question2 = Dropdown(title="Enter current status")
> 		Question2.choices = [ (1, "Alive and Kicking"), (2, "Comatose"), (3, "Dead"), ...]
>
> Is there anything out there that would be close or do you have any suggestions.

Are you familiar with z3c.form?

https://pypi.python.org/pypi/z3c.form

Given that it's part of the Zope web framework, it's fairly heavily 
geared towards working with HTTP requests, but it's quite possible to 
only use the parts that want. For your requirement, you could probably 
get a long way with using zope.schema for defining the forms, and then 
customising some of the templates to render them appropriately. The 
provided widgets are easily extensible, so adding support for the vendor 
form syntax - possibly as additional templates alongside the HTML ones - 
should be doable.



From __peter__ at web.de  Fri Mar 28 03:46:29 2014
From: __peter__ at web.de (Peter Otten)
Date: Fri, 28 Mar 2014 08:46:29 +0100
Subject: Python language hack for C-style programmers [DO NOT USE!] :-)
References: <20140327110856.14991bb0@bigbox.christie.dr>
 <CAPTjJmoSEiBEO9fXfwM7mGywty+dT8erBqeu2mpyrxAf12udcw@mail.gmail.com>
 <lh2jsg$cqu$1@ger.gmane.org>
 <CAPTjJmoU-Aa_Y2DDHzCyzMNUfNnuV2i2gsHWZP3gKBhzrXjLzw@mail.gmail.com>
Message-ID: <lh39cc$6cd$1@ger.gmane.org>

Chris Angelico wrote:

> On Fri, Mar 28, 2014 at 12:44 PM, Dave Angel <davea at davea.name> wrote:
>>> if (array m = Regexp.split2(some_pattern, some_string))
>>>     do_something(m);
>>>
>>
>> I don't know for certain about if, but you can declare (in C++) a
>>  new variable in for, which is a superset of if. Scope ends when
>>  the for does.
> 
> Yeah, but only a for, AFAIK. Not an if or a while.

Why would you guess if you can check? Just fire up the interactive 
interpreter^W^W compiler:

$ cat ifdecl.c
#include <stdio.h>

int main()
{
  if(int i=42)
    printf("%d\n", i);
}
$ gcc ifdecl.c
ifdecl.c: In function ?main?:
ifdecl.c:5:6: error: expected expression before ?int?
   if(int i=42)
      ^
ifdecl.c:6:20: error: ?i? undeclared (first use in this function)
     printf("%d\n", i);
                    ^
ifdecl.c:6:20: note: each undeclared identifier is reported only once for 
each function it appears in
$ g++ ifdecl.c
$ ./a.out 
42




From rosuav at gmail.com  Fri Mar 28 03:51:13 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 18:51:13 +1100
Subject: Python language hack for C-style programmers [DO NOT USE!] :-)
In-Reply-To: <lh39cc$6cd$1@ger.gmane.org>
References: <20140327110856.14991bb0@bigbox.christie.dr>
 <CAPTjJmoSEiBEO9fXfwM7mGywty+dT8erBqeu2mpyrxAf12udcw@mail.gmail.com>
 <lh2jsg$cqu$1@ger.gmane.org>
 <CAPTjJmoU-Aa_Y2DDHzCyzMNUfNnuV2i2gsHWZP3gKBhzrXjLzw@mail.gmail.com>
 <lh39cc$6cd$1@ger.gmane.org>
Message-ID: <CAPTjJmrXbB+3sK9BBg-PMik0wFB0XpzzqbidL1r1qUuuSNa2fQ@mail.gmail.com>

On Fri, Mar 28, 2014 at 6:46 PM, Peter Otten <__peter__ at web.de> wrote:
> Why would you guess if you can check? Just fire up the interactive
> interpreter^W^W compiler:

Partly because there's a difference between valid C++ and valid input
to the G++ compiler :) Knowing that it works with g++ doesn't tell me
that it's actually valid, and I don't feel like digging into the specs
to find out where you're guaranteed to be allowed to do that. (I could
probably test it with one of the language spec options, but then it
still depends on the exact version of GCC and the exact spec chosen.)

ChrisA


From __peter__ at web.de  Fri Mar 28 04:26:05 2014
From: __peter__ at web.de (Peter Otten)
Date: Fri, 28 Mar 2014 09:26:05 +0100
Subject: Python language hack for C-style programmers [DO NOT USE!] :-)
References: <20140327110856.14991bb0@bigbox.christie.dr>
 <CAPTjJmoSEiBEO9fXfwM7mGywty+dT8erBqeu2mpyrxAf12udcw@mail.gmail.com>
 <lh2jsg$cqu$1@ger.gmane.org>
 <CAPTjJmoU-Aa_Y2DDHzCyzMNUfNnuV2i2gsHWZP3gKBhzrXjLzw@mail.gmail.com>
 <lh39cc$6cd$1@ger.gmane.org>
 <CAPTjJmrXbB+3sK9BBg-PMik0wFB0XpzzqbidL1r1qUuuSNa2fQ@mail.gmail.com>
Message-ID: <lh3bme$ubb$1@ger.gmane.org>

Chris Angelico wrote:

> On Fri, Mar 28, 2014 at 6:46 PM, Peter Otten <__peter__ at web.de> wrote:
>> Why would you guess if you can check? Just fire up the interactive
>> interpreter^W^W compiler:
> 
> Partly because there's a difference between valid C++ and valid input
> to the G++ compiler :) Knowing that it works with g++ doesn't tell me
> that it's actually valid, and I don't feel like digging into the specs
> to find out where you're guaranteed to be allowed to do that. (I could
> probably test it with one of the language spec options, but then it
> still depends on the exact version of GCC and the exact spec chosen.)

I don't have the spec handy, only an old copy of "The C++ Programming 
Language" which has

"""
To avoid accidental misuse of a variable, it is usually a good idea to 
introduce the variable into the smallest scope possible [and] to delay the 
definition of a local variable until one can give it an initial value.
[...] One of the most elegant applications of these two principles is to 
declare a variable in a condition. Consider:

if (double d = prim(true)) {
    left /= d;
    break;
}
"""




From rosuav at gmail.com  Fri Mar 28 04:38:52 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 28 Mar 2014 19:38:52 +1100
Subject: Python language hack for C-style programmers [DO NOT USE!] :-)
In-Reply-To: <lh3bme$ubb$1@ger.gmane.org>
References: <20140327110856.14991bb0@bigbox.christie.dr>
 <CAPTjJmoSEiBEO9fXfwM7mGywty+dT8erBqeu2mpyrxAf12udcw@mail.gmail.com>
 <lh2jsg$cqu$1@ger.gmane.org>
 <CAPTjJmoU-Aa_Y2DDHzCyzMNUfNnuV2i2gsHWZP3gKBhzrXjLzw@mail.gmail.com>
 <lh39cc$6cd$1@ger.gmane.org>
 <CAPTjJmrXbB+3sK9BBg-PMik0wFB0XpzzqbidL1r1qUuuSNa2fQ@mail.gmail.com>
 <lh3bme$ubb$1@ger.gmane.org>
Message-ID: <CAPTjJmp3f56q4hcn0_Yg1iWZ7RmDV5+cMNfY9HCEAyCO3R5m5g@mail.gmail.com>

On Fri, Mar 28, 2014 at 7:26 PM, Peter Otten <__peter__ at web.de> wrote:
> One of the most elegant applications of these two principles is to
> declare a variable in a condition. Consider:
>
> if (double d = prim(true)) {
>     left /= d;
>     break;
> }

Okay! Then I withdraw the "or, to my knowledge, C++" part of my
original statement. It's a useful feature, if not a unique one.

ChrisA


From guru at digitalfantasy.it  Fri Mar 28 04:44:43 2014
From: guru at digitalfantasy.it (Daniele Forghieri)
Date: Fri, 28 Mar 2014 09:44:43 +0100
Subject: Using query parameters subtitution outside of execute()
Message-ID: <5335367B.2090604@digitalfantasy.it>

Hi to all. I'm using sqlite3 with python 2.7 on windows.

I use the query substitution parameters in my query but I need to pass 
part of the query to a function, something like (it's not the real 
examples, just to clarify the question):

def loadAll(cursor, id, queryAdd = None):
     if queryAdd is None:
         qry =  'select * from files where catalog = ?'
     else:
         qry = 'select * from files where catalog = ? and %s' % (queryAdd))

     cursor.execute(qry, (id, ))
     ...

I would like to use the query substitution even when I create, in 
another piece of code, the queryAdd part, something like:

queryAdd = cursor.querySubst('enabled = ? and hide = ? and data > ?', 
(enabled, hidden, min_date, ))

when the function take care of the date format, quoting the parameter 
and so on

It's possible or not ?

Thanks in advance

     Daniele Forghieri






From alister.nospam.ware at ntlworld.com  Fri Mar 28 05:04:07 2014
From: alister.nospam.ware at ntlworld.com (alister)
Date: Fri, 28 Mar 2014 09:04:07 GMT
Subject: meta language to define forms
Message-ID: <bWaZu.203498$Su4.169011@fx02.am4>

On Fri, 28 Mar 2014 14:57:11 +1100, Chris Angelico wrote:

> On Fri, Mar 28, 2014 at 2:44 PM, Rustom Mody <rustompmody at gmail.com>
> wrote:
>> [BTW I consider the windows registry cleaner than the linux /etc for
>> the same reason]
> 
> And if I felt like trolling, I'd point out that there are a lot more
> search engine hits for "windows registry cleaner" than "linux etc
> cleaner". :)
> 
> ChrisA

Not to mention that the windows registry is a Single Point of failure.
if it gets corrupt (by 1 minor program crashing whilst writing to it)the 
chances are your OS is broken to the point of being unfixable.
at least with the Linux system (& the multiple config files of windows 3 
& earlier) it can normaly be fixed with a simple text editor.



From __peter__ at web.de  Fri Mar 28 05:16:07 2014
From: __peter__ at web.de (Peter Otten)
Date: Fri, 28 Mar 2014 10:16:07 +0100
Subject: Using query parameters subtitution outside of execute()
References: <5335367B.2090604@digitalfantasy.it>
Message-ID: <lh3ek9$236$1@ger.gmane.org>

Daniele Forghieri wrote:

> Hi to all. I'm using sqlite3 with python 2.7 on windows.
> 
> I use the query substitution parameters in my query but I need to pass
> part of the query to a function, something like (it's not the real
> examples, just to clarify the question):
> 
> def loadAll(cursor, id, queryAdd = None):
>      if queryAdd is None:
>          qry =  'select * from files where catalog = ?'
>      else:
>          qry = 'select * from files where catalog = ? and %s' %
>          (queryAdd))
> 
>      cursor.execute(qry, (id, ))
>      ...
> 
> I would like to use the query substitution even when I create, in
> another piece of code, the queryAdd part, something like:
> 
> queryAdd = cursor.querySubst('enabled = ? and hide = ? and data > ?',
> (enabled, hidden, min_date, ))
> 
> when the function take care of the date format, quoting the parameter
> and so on
> 
> It's possible or not ?

You can use named parameters

http://docs.python.org/dev/library/sqlite3.html#cursor-objects

Your function might become (untested)

def load_all(cursor, parameters, condition="catalog = :id"):
    query =  'select * from files where ' + condition
    cursor.execute(query, parameters)
    ...

load_all(
    cursor, dict(id=42, fromdate=datetime.date.today()),
    condition="catalog = :id and date >= :fromdate")



From steve+comp.lang.python at pearwood.info  Fri Mar 28 07:11:54 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 28 Mar 2014 11:11:54 GMT
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
Message-ID: <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Thu, 27 Mar 2014 20:29:17 -0400, Roy Smith wrote:

> In article <5334b747$0$29994$c3e8da3$5496439d at news.astraweb.com>,
>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
> 
>> On Thu, 27 Mar 2014 08:52:24 -0400, Roy Smith wrote:
>> 
>> > In article <mailman.8613.1395917059.18130.python-list at python.org>,
>> >  Chris Angelico <rosuav at gmail.com> wrote:
>> >> It's not "equally braindead", it follows a simple and logical rule:
>> >> Only the day portion is negative.
>> > 
>> > Simple and logical, yes.  But also entirely braindead.
>> 
>> Do you think it is "braindead" for __str__ to return something which
>> follows the internal representation of the object?
> 
> Yes.  The whole idea of OOD is to decouple internal representation from
> external behavior.

The *whole* idea? You don't think that encapsulation and inheritance 
might also be involved? *wink*

Besides, there's a difference between internal _representation_ and 
internal _implementation_. I don't always choose my words carefully, but 
this was one of those times :-)

A timedelta object *represents* a delta as (days + seconds + 
microseconds). That is part of the interface, not implementation. How it 
is actually implemented is irrelevant. (If I were to take a wild guess, 
I'd predict that timedeltas record the total number of seconds.)


>> > Give ma a real-life situation where you would want such behavior.
>> 
>> Easy -- I'm debugging timedelta routines, and I want to easily see that
>> the timedeltas calculated match what I expect them to be when I print
>> them. The quickest, easiest and simplest way is for str(timedelta) to
>> follow the internal representation.
> 
> That's what __repr__() is for.

Actually, __repr__ should, if practical, match the constructor for the 
object:

py> import datetime
py> t = datetime.timedelta(2, 3)
py> eval(repr(t)) == t
True


>> Oh look, that's exactly what the docs say:
>> 
>> "String representations of timedelta objects are normalized similarly
>> to their internal representation. This leads to somewhat unusual
>> results for negative timedeltas."
> 
> Yes, I know that's what the docs say.  That's why it's not an
> implementation bug.  It's a design bug :-)

I don't think it is. Given a timedelta object with D days, S seconds and 
M microseconds, I think that it is a very useful property if the string 
also says it has D days, S seconds and M microseconds. Would you not 
agree? I think that this would be silly:

str(timedelta(1, 0, 0))
=> '0 day, 24:01:-5184000.0'

even though it would be correct. So we can dismiss the idea that the str 
of a timedelta should be free to arbitrarily vary from the internal 
representation.

I consider this to be a useful constraint on timedelta's internal 
representation (not implementation): the seconds and microseconds should 
be normalised to the half-open intervals, 0 to 86400 for seconds and 0 to 
1000000 for microseconds. Given that constraint, and the previous 
constraint that strings should show the same number of days etc., and we 
have the current behaviour.

Both constraints are reasonable. You have to weaken one, or the other, in 
order to get the result you want. That's not necessarily unreasonable, 
but neither is it a given. Python-Dev is not normally "braindead", so at 
least given them the benefit of the doubt that *maybe* there's some good 
reason we haven't thought of.


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From guru at digitalfantasy.it  Fri Mar 28 07:54:11 2014
From: guru at digitalfantasy.it (Daniele Forghieri)
Date: Fri, 28 Mar 2014 12:54:11 +0100
Subject: Using query parameters subtitution outside of execute()
In-Reply-To: <lh3ek9$236$1@ger.gmane.org>
References: <5335367B.2090604@digitalfantasy.it> <lh3ek9$236$1@ger.gmane.org>
Message-ID: <533562E3.1000400@digitalfantasy.it>

Il 28/03/2014 10:16, Peter Otten ha scritto:
> Daniele Forghieri wrote:
>
>> Hi to all. I'm using sqlite3 with python 2.7 on windows.
>>
>> I use the query substitution parameters in my query but I need to pass
>> part of the query to a function, something like (it's not the real
>> examples, just to clarify the question):
>>
>> def loadAll(cursor, id, queryAdd = None):
>>       if queryAdd is None:
>>           qry =  'select * from files where catalog = ?'
>>       else:
>>           qry = 'select * from files where catalog = ? and %s' %
>>           (queryAdd))
>>
>>       cursor.execute(qry, (id, ))
>>       ...
>>
>> I would like to use the query substitution even when I create, in
>> another piece of code, the queryAdd part, something like:
>>
>> queryAdd = cursor.querySubst('enabled = ? and hide = ? and data > ?',
>> (enabled, hidden, min_date, ))
>>
>> when the function take care of the date format, quoting the parameter
>> and so on
>>
>> It's possible or not ?
> You can use named parameters
>
> http://docs.python.org/dev/library/sqlite3.html#cursor-objects
>
> Your function might become (untested)
>
> def load_all(cursor, parameters, condition="catalog = :id"):
>      query =  'select * from files where ' + condition
>      cursor.execute(query, parameters)
>      ...
>
> load_all(
>      cursor, dict(id=42, fromdate=datetime.date.today()),
>      condition="catalog = :id and date >= :fromdate")
>

     Thank. With this I can solve the problem but I have to specify the 
query twice and if I have to change something I need to made it 
everywhere I use the function and is something I would like to avoid.

     I also don't like very mush to pass or create a dict for a function 
call but that's probably me coming from old plain C ;)

     Daniele Forghieri





From rustompmody at gmail.com  Fri Mar 28 08:11:41 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 28 Mar 2014 05:11:41 -0700 (PDT)
Subject: meta language to define forms
In-Reply-To: <bWaZu.203498$Su4.169011@fx02.am4>
References: <bWaZu.203498$Su4.169011@fx02.am4>
Message-ID: <e50a1ec3-90b8-4204-9984-dbf6240cfc2c@googlegroups.com>

On Friday, March 28, 2014 2:34:07 PM UTC+5:30, alister wrote:
> On Fri, 28 Mar 2014 14:57:11 +1100, Chris Angelico wrote:

> > wrote:
> >> [BTW I consider the windows registry cleaner than the linux /etc for
> >> the same reason]
> > And if I felt like trolling, I'd point out that there are a lot more
> > search engine hits for "windows registry cleaner" than "linux etc
> > cleaner". :)
> > ChrisA

> Not to mention that the windows registry is a Single Point of failure.
> if it gets corrupt (by 1 minor program crashing whilst writing to it)the 
> chances are your OS is broken to the point of being unfixable.
> at least with the Linux system (& the multiple config files of windows 3 
> & earlier) it can normaly be fixed with a simple text editor.

This sure used to be true in the windows 95-98 era.
I dont believe its been this way for more than a decade.
XP onwards there's enough redundancy+fallback+checkpointing so that we rarely
really hear of this any more [But Im not a windows guy :-)]

On the other hand in linux I find that when something is upgraded and needs to 
upgrade *its own* config files in /etc it can often have trouble.

I trace this to the fact that what is needed is mostly a simple key-value store
holding some config parameters.  What is stored is usually a general script.
As a result http://www.w3.org/2001/tag/doc/leastPower.html kicks in.


From marko at pacujo.net  Fri Mar 28 08:14:48 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 28 Mar 2014 14:14:48 +0200
Subject: meta language to define forms
References: <bWaZu.203498$Su4.169011@fx02.am4>
 <e50a1ec3-90b8-4204-9984-dbf6240cfc2c@googlegroups.com>
Message-ID: <87a9cawmdj.fsf@elektro.pacujo.net>

Rustom Mody <rustompmody at gmail.com>:

> On the other hand in linux I find that when something is upgraded and
> needs to upgrade *its own* config files in /etc it can often have
> trouble.

Linux (service) configuration has given me a lot of grief as well.
However, I don't thing anything should need to upgrade config files. The
packaging tools leave the old config file in place, which is the right
thing. The service had better support the old config file format with no
interpretation changes.


Marko


From rustompmody at gmail.com  Fri Mar 28 08:25:26 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 28 Mar 2014 05:25:26 -0700 (PDT)
Subject: meta language to define forms
In-Reply-To: <87a9cawmdj.fsf@elektro.pacujo.net>
References: <bWaZu.203498$Su4.169011@fx02.am4>
 <e50a1ec3-90b8-4204-9984-dbf6240cfc2c@googlegroups.com>
 <87a9cawmdj.fsf@elektro.pacujo.net>
Message-ID: <71797ba5-23f4-499e-aabd-e3d64c22064f@googlegroups.com>

On Friday, March 28, 2014 5:44:48 PM UTC+5:30, Marko Rauhamaa wrote:
> Rustom Mody wrote:

> > On the other hand in linux I find that when something is upgraded and
> > needs to upgrade *its own* config files in /etc it can often have
> > trouble.

> Linux (service) configuration has given me a lot of grief as well.
> However, I don't thing anything should need to upgrade config files.

Strange thing to say.
There may be new config options. The defaults may be altered with good reason.
This needs a new file

OTOH the user may have his own old altered defaults.
So integrating the two is not exactly an easy problem.

And what apt does in this case is to drop you into some half-assed
interactive (so-called) mode saying some file has changed -- Do you
want to keep old, choose new, drop into a shell, or some other half-baked
options

> The packaging tools leave the old config file in place, which is the
> right thing.

They dont exactly do that -- see above



From roy at panix.com  Fri Mar 28 08:30:11 2014
From: roy at panix.com (Roy Smith)
Date: Fri, 28 Mar 2014 08:30:11 -0400
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
 <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-BD9428.08301128032014@news.panix.com>

In article <533558fa$0$29994$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> > Yes.  The whole idea of OOD is to decouple internal representation from
> > external behavior.
> 
> The *whole* idea? You don't think that encapsulation and inheritance 
> might also be involved? *wink*

I'm not sure how "decoupling internal representation from external 
behavior" is substantially different from encapsulation.  And, no, I 
don't think inheritance is a fundamental characteristic of OOD, nudge 
nudge.


From esj at harvee.org  Fri Mar 28 08:11:11 2014
From: esj at harvee.org (Eric S. Johansson)
Date: Fri, 28 Mar 2014 08:11:11 -0400
Subject: meta language to define forms
In-Reply-To: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
References: <DCD75728F460F14586086EA606E83082011A8E01E3@ACEVXCHMBX1001.ADVENTISTCORP.NET>
Message-ID: <533566DF.5020402@harvee.org>


On 3/27/2014 4:56 PM, Sells, Fred wrote:
> I'm trying to use python classes and members to define complex data entry forms as a meta language
>
> The idea is to use a nice clean syntax like Python to define form content, then render it as HTML but only as a review tool for users,  The actual rendering would go into a database to let a vendor's tool generate the form in a totally non-standard syntax that's really clunky.

I've run into a similar problem when building a framework for 
programming by speech and web application development. Although, my 
goals were different. I want to something you can create with speech 
recognition without too much of a vocal load or requiring 
extensive/specialized editor changes. One could say I was trying to make 
it possible to develop web apps in Microsoft Word. :-)

The first attempt was a bracketed notation that was in effect a very 
high level domain specific notation. The next attempt is trying to 
eliminate the use of bracketing notation to specify scope and said use 
indentation.

Like you, the environment consists of little bits of Python that takes 
what you want in the form/user interface and generates the HTML and 
JavaScript for presentation in action.

To use your example, my notation would look something like this

: Form
   uses section_title; Enter Patient Vital Signs
   uses number_question; 3, Enter pulse rate
   : drop_down_list
     uses title; Enter current status
     uses choices; 1, alive and kicking
     uses choices; 2, comatose
     uses choices; 3, there's another dead Bishop on the landing

The: names refer to the methods that generate the code using the 
arguments provided by the statements within the: name definition. as 
refine what is your trying to do, you can make the: names more and more 
meta-and less and less implementation details. For example, one of the 
experiences that told me the bracketed notation was not going to fly was 
when I created a storefront for telescope shop. I created notation that 
expressed the work of the store not the display of the store 
information. Obviously the output of the notation was the display data 
but it operated in a way that the storekeeper understood and could take 
care of himself which was impossible with ordinary HTML and completely 
impossible if you added something like bootstrap.

And before somebody kicks up a fuss About the notation, let me say that 
this was aimed at disabled developers who cannot type anymore or who 
want to listen because they cannot see. What I have created is far more 
productive and speakable than any of the other systems out there.

--- eric



From marko at pacujo.net  Fri Mar 28 09:04:50 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 28 Mar 2014 15:04:50 +0200
Subject: meta language to define forms
References: <bWaZu.203498$Su4.169011@fx02.am4>
 <e50a1ec3-90b8-4204-9984-dbf6240cfc2c@googlegroups.com>
 <87a9cawmdj.fsf@elektro.pacujo.net>
 <71797ba5-23f4-499e-aabd-e3d64c22064f@googlegroups.com>
Message-ID: <8761mywk25.fsf@elektro.pacujo.net>

Rustom Mody <rustompmody at gmail.com>:

> On Friday, March 28, 2014 5:44:48 PM UTC+5:30, Marko Rauhamaa wrote:
>> I don't thing anything should need to upgrade config files.
>
> Strange thing to say.
> There may be new config options.

The missing options should default to the old behavior.

> The defaults may be altered with good reason.

Occasionally, but the reason had better be *really* good. It is like
changing a programming API. You live with your bad decisions.

> And what apt does in this case is to drop you into some half-assed
> interactive (so-called) mode saying some file has changed -- Do you
> want to keep old, choose new, drop into a shell, or some other
> half-baked options

RPM won't overwrite modified config files but just places the new
version there next to the old one under a different name (and gives a
warning). RPM isn't perfect, but that is the sane thing to do.


Marko


From marko at pacujo.net  Fri Mar 28 09:10:15 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 28 Mar 2014 15:10:15 +0200
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
 <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-BD9428.08301128032014@news.panix.com>
Message-ID: <871txmwjt4.fsf@elektro.pacujo.net>

Roy Smith <roy at panix.com>:

> I'm not sure how "decoupling internal representation from external 
> behavior" is substantially different from encapsulation.

Yes, that's encapsulation. The idea of encapsulation is older than OO.

> And, no, I don't think inheritance is a fundamental characteristic of
> OOD, nudge nudge.

Inheritance was there with Simula so I think it's high up there with OO.

If encapsulation exists outside OO and inheritance is not key to it,
what is OO then, a marketing term?

(It's a different thing, then, that encapsulation and inheritance are
mutually exclusive principles.)


Marko


From rosuav at gmail.com  Fri Mar 28 09:19:38 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 00:19:38 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <871txmwjt4.fsf@elektro.pacujo.net>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
 <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-BD9428.08301128032014@news.panix.com>
 <871txmwjt4.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmqZ_D6FLYpX6CxLkcnzt1AntRkd4xBkQ2NQE8pL94REyw@mail.gmail.com>

On Sat, Mar 29, 2014 at 12:10 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> If encapsulation exists outside OO and inheritance is not key to it,
> what is OO then, a marketing term?
>

Yep, OO is a marketing term. So's programming - after all, it's just
flipping bits in memory... we only pretend it means anything. Do I
really exist, or do I just think I do?

ChrisA


From roy at panix.com  Fri Mar 28 09:20:18 2014
From: roy at panix.com (Roy Smith)
Date: Fri, 28 Mar 2014 09:20:18 -0400
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
 <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-BD9428.08301128032014@news.panix.com>
 <871txmwjt4.fsf@elektro.pacujo.net>
Message-ID: <roy-F15922.09201828032014@news.panix.com>

In article <871txmwjt4.fsf at elektro.pacujo.net>,
 Marko Rauhamaa <marko at pacujo.net> wrote:

> what is OO then, a marketing term?

Sometimes, I think it must be :-)

> (It's a different thing, then, that encapsulation and inheritance are
> mutually exclusive principles.)

There're certainly not mutually exclusive.  Mutually exclusive means if 
you have one, you can't have the other.

I think the phrase you're looking for is "orthogonal concepts".  You can 
have either, or both, or neither, and the existence of one doesn't imply 
anything about the existence of the other.


From roy at panix.com  Fri Mar 28 09:22:15 2014
From: roy at panix.com (Roy Smith)
Date: Fri, 28 Mar 2014 09:22:15 -0400
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
 <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-BD9428.08301128032014@news.panix.com>
 <871txmwjt4.fsf@elektro.pacujo.net>
 <mailman.8667.1396012782.18130.python-list@python.org>
Message-ID: <roy-E63942.09221528032014@news.panix.com>

In article <mailman.8667.1396012782.18130.python-list at python.org>,
 Chris Angelico <rosuav at gmail.com> wrote:

> On Sat, Mar 29, 2014 at 12:10 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> > If encapsulation exists outside OO and inheritance is not key to it,
> > what is OO then, a marketing term?
> >
> 
> Yep, OO is a marketing term. So's programming - after all, it's just
> flipping bits in memory... we only pretend it means anything. Do I
> really exist, or do I just think I do?
> 
> ChrisA

The real question is, what does this print:

c1 = ChrisA()
c2 = ChrisA()
print c1 == c2
print c2 is c2


From tanmay.kansara at gmail.com  Fri Mar 28 09:27:44 2014
From: tanmay.kansara at gmail.com (tanmay.kansara at gmail.com)
Date: Fri, 28 Mar 2014 06:27:44 -0700 (PDT)
Subject: implementing download using a url call
In-Reply-To: <mailman.8652.1395973614.18130.python-list@python.org>
References: <d58f6cea-c290-41f6-8f06-47c317243a8f@googlegroups.com>
 <mailman.8652.1395973614.18130.python-list@python.org>
Message-ID: <31de94dd-2ed7-431b-acb8-4771fe352031@googlegroups.com>

Hey

Sorry, I should make it more clear. We had a 3rd party that was serving stub builds and they have their URLs on various pages(random sites). We control the sub-domain, so i can send that traffic to wherever I want. I am looking to create logic that takes that incoming parameter and serves an exe file. 
With the logic I posted, the user gets the file, but also gets a new blank page. I would like to keep the user on the 3rd part website. 

Hope this clarifies. 

Thanks


From rosuav at gmail.com  Fri Mar 28 09:32:48 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 00:32:48 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <roy-E63942.09221528032014@news.panix.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
 <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-BD9428.08301128032014@news.panix.com>
 <871txmwjt4.fsf@elektro.pacujo.net>
 <mailman.8667.1396012782.18130.python-list@python.org>
 <roy-E63942.09221528032014@news.panix.com>
Message-ID: <CAPTjJmoqnkEXAUNWizpO0++mZ9QrMch8-HoNMmeACb6WSf2EvQ@mail.gmail.com>

On Sat, Mar 29, 2014 at 12:22 AM, Roy Smith <roy at panix.com> wrote:
> In article <mailman.8667.1396012782.18130.python-list at python.org>,
>  Chris Angelico <rosuav at gmail.com> wrote:
>
>> On Sat, Mar 29, 2014 at 12:10 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> > If encapsulation exists outside OO and inheritance is not key to it,
>> > what is OO then, a marketing term?
>> >
>>
>> Yep, OO is a marketing term. So's programming - after all, it's just
>> flipping bits in memory... we only pretend it means anything. Do I
>> really exist, or do I just think I do?
>>
>> ChrisA
>
> The real question is, what does this print:
>
> c1 = ChrisA()
> c2 = ChrisA()
> print c1 == c2
> print c2 is c2

And if you could answer that, you would know whether my mother was
right when, in exasperation, she would say "Your design follows the
singleton principle!". Okay, so she actually was more likely to say
"You are one of a kind!", but it comes to the same thing...

ChrisA


From rustompmody at gmail.com  Fri Mar 28 09:30:17 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 28 Mar 2014 06:30:17 -0700 (PDT)
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <roy-E63942.09221528032014@news.panix.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
 <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-BD9428.08301128032014@news.panix.com>
 <871txmwjt4.fsf@elektro.pacujo.net>
 <mailman.8667.1396012782.18130.python-list@python.org>
 <roy-E63942.09221528032014@news.panix.com>
Message-ID: <5533a78f-c1e0-4d83-81c0-d790106ec9bd@googlegroups.com>

On Friday, March 28, 2014 6:52:15 PM UTC+5:30, Roy Smith wrote:
>  Chris Angelico wrote:

> > On Sat, Mar 29, 2014 at 12:10 AM, Marko Rauhamaa wrote:
> > > If encapsulation exists outside OO and inheritance is not key to it,
> > > what is OO then, a marketing term?
> > Yep, OO is a marketing term. So's programming - after all, it's just
> > flipping bits in memory... we only pretend it means anything. Do I
> > really exist, or do I just think I do?
> > ChrisA

> The real question is, what does this print:

> c1 = ChrisA()
> c2 = ChrisA()
> print c1 == c2
> print c2 is c2

OO is of course a marketing term

Unicode OTOH is the real cure for all diseases

Proof by example:
Replace the last with
print c2 ? c2 
or even better
print c2 ? c2

No confusion any more... 
See? We all know now who (what?) Chris is!


From __peter__ at web.de  Fri Mar 28 09:53:06 2014
From: __peter__ at web.de (Peter Otten)
Date: Fri, 28 Mar 2014 14:53:06 +0100
Subject: Using query parameters subtitution outside of execute()
References: <5335367B.2090604@digitalfantasy.it> <lh3ek9$236$1@ger.gmane.org>
 <533562E3.1000400@digitalfantasy.it>
Message-ID: <lh3urk$e1g$1@ger.gmane.org>

Daniele Forghieri wrote:

> Il 28/03/2014 10:16, Peter Otten ha scritto:
>> Daniele Forghieri wrote:
>>
>>> Hi to all. I'm using sqlite3 with python 2.7 on windows.
>>>
>>> I use the query substitution parameters in my query but I need to pass
>>> part of the query to a function, something like (it's not the real
>>> examples, just to clarify the question):
>>>
>>> def loadAll(cursor, id, queryAdd = None):
>>>       if queryAdd is None:
>>>           qry =  'select * from files where catalog = ?'
>>>       else:
>>>           qry = 'select * from files where catalog = ? and %s' %
>>>           (queryAdd))
>>>
>>>       cursor.execute(qry, (id, ))
>>>       ...
>>>
>>> I would like to use the query substitution even when I create, in
>>> another piece of code, the queryAdd part, something like:
>>>
>>> queryAdd = cursor.querySubst('enabled = ? and hide = ? and data > ?',
>>> (enabled, hidden, min_date, ))
>>>
>>> when the function take care of the date format, quoting the parameter
>>> and so on
>>>
>>> It's possible or not ?
>> You can use named parameters
>>
>> http://docs.python.org/dev/library/sqlite3.html#cursor-objects
>>
>> Your function might become (untested)
>>
>> def load_all(cursor, parameters, condition="catalog = :id"):
>>      query =  'select * from files where ' + condition
>>      cursor.execute(query, parameters)
>>      ...
>>
>> load_all(
>>      cursor, dict(id=42, fromdate=datetime.date.today()),
>>      condition="catalog = :id and date >= :fromdate")
>>
> 
>      Thank. With this I can solve the problem but I have to specify the
> query twice and if I have to change something I need to made it
> everywhere I use the function and is something I would like to avoid.

How about that one:

def query_subst(sql, parameters):
    return sql, parameters

def load_all(cursor, id, query_add=None):
    query =  'select * from files where catalog = ?'
    parameters = (id,)
    if query_add is not None:
        query += " and " + query_add[0]
        parameters += query_add[1]
    cursor.execute(query, parameters)
    ...

enabled = True
hidden = False
min_date = datetime.date.today()

query_add = query_subst(
    'enabled = ? and hide = ? and date > ?', 
    (enabled, hidden, min_date))

load_all(cs, 42, query_add)

>      I also don't like very mush to pass or create a dict for a function
> call but that's probably me coming from old plain C ;)

Get over it ;)




From guru at digitalfantasy.it  Fri Mar 28 10:16:05 2014
From: guru at digitalfantasy.it (Daniele Forghieri)
Date: Fri, 28 Mar 2014 15:16:05 +0100
Subject: Using query parameters subtitution outside of execute()
In-Reply-To: <lh3urk$e1g$1@ger.gmane.org>
References: <5335367B.2090604@digitalfantasy.it> <lh3ek9$236$1@ger.gmane.org>
 <533562E3.1000400@digitalfantasy.it> <lh3urk$e1g$1@ger.gmane.org>
Message-ID: <53358425.5020109@digitalfantasy.it>

Il 28/03/2014 14:53, Peter Otten ha scritto:
> Daniele Forghieri wrote:
>
>> Il 28/03/2014 10:16, Peter Otten ha scritto:
>>> Daniele Forghieri wrote:
>>>
>>>> Hi to all. I'm using sqlite3 with python 2.7 on windows.
>>>>
>>>> I use the query substitution parameters in my query but I need to pass
>>>> part of the query to a function, something like (it's not the real
>>>> examples, just to clarify the question):
>>>>
>>>> def loadAll(cursor, id, queryAdd = None):
>>>>        if queryAdd is None:
>>>>            qry =  'select * from files where catalog = ?'
>>>>        else:
>>>>            qry = 'select * from files where catalog = ? and %s' %
>>>>            (queryAdd))
>>>>
>>>>        cursor.execute(qry, (id, ))
>>>>        ...
>>>>
>>>> I would like to use the query substitution even when I create, in
>>>> another piece of code, the queryAdd part, something like:
>>>>
>>>> queryAdd = cursor.querySubst('enabled = ? and hide = ? and data > ?',
>>>> (enabled, hidden, min_date, ))
>>>>
>>>> when the function take care of the date format, quoting the parameter
>>>> and so on
>>>>
>>>> It's possible or not ?
>>> You can use named parameters
>>>
>>> http://docs.python.org/dev/library/sqlite3.html#cursor-objects
>>>
>>> Your function might become (untested)
>>>
>>> def load_all(cursor, parameters, condition="catalog = :id"):
>>>       query =  'select * from files where ' + condition
>>>       cursor.execute(query, parameters)
>>>       ...
>>>
>>> load_all(
>>>       cursor, dict(id=42, fromdate=datetime.date.today()),
>>>       condition="catalog = :id and date >= :fromdate")
>>>
>>       Thank. With this I can solve the problem but I have to specify the
>> query twice and if I have to change something I need to made it
>> everywhere I use the function and is something I would like to avoid.
> How about that one:
>
> def query_subst(sql, parameters):
>      return sql, parameters
>
> def load_all(cursor, id, query_add=None):
>      query =  'select * from files where catalog = ?'
>      parameters = (id,)
>      if query_add is not None:
>          query += " and " + query_add[0]
>          parameters += query_add[1]
>      cursor.execute(query, parameters)
>      ...
>
> enabled = True
> hidden = False
> min_date = datetime.date.today()
>
> query_add = query_subst(
>      'enabled = ? and hide = ? and date > ?',
>      (enabled, hidden, min_date))
>
> load_all(cs, 42, query_add)

     This one is, IMHO, cleaner and more manageable!

     Thank you very very much, I really appreciate your help.

>>       I also don't like very mush to pass or create a dict for a function
>> call but that's probably me coming from old plain C ;)
> Get over it ;)
>
>

         I'm trying but the old habits comes out, the first time I need 
to parse a string I do it like in C, looking at every single char using 
a couple of help function: the performance were really horrible, the 
memory used was huge than I change the way I do things (and start to use 
sqlite3 to store my data instead of using text files, parsed by a 
proprietary lib).

         The worse is the contrary, when I must use C and I think 'Here 
I use a dictionary, at the end convert it in a list that I sort with 
that key ...' only to realize that I don't have dictionary and the list 
I can use are very less manageable that the ones I used in Python ...

         It seems to me that going from C to Python you start writing 
inefficient code or write more lines than an average Python programmer 
but 'something moves' and the result happens. Moving from Python to C I 
always feel like I missed something and the first approach, good for 
Python, is simply not working in C ;(

     Thanks again

     Daniele Forghieri


From marko at pacujo.net  Fri Mar 28 10:34:36 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 28 Mar 2014 16:34:36 +0200
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
 <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-BD9428.08301128032014@news.panix.com>
 <871txmwjt4.fsf@elektro.pacujo.net>
 <roy-F15922.09201828032014@news.panix.com>
Message-ID: <87ob0qv1c3.fsf@elektro.pacujo.net>

Roy Smith <roy at panix.com>:

> There're certainly not mutually exclusive. Mutually exclusive means if
> you have one, you can't have the other.

Correct.

The classic inheritance diamond:

   class A(B, C):
       def add_bean(self):
           ??? # how to implement

   class B(D): pass
   class C(D): pass

   class D:
       def __init__(self):
           self.beans = 0

       def add_bean(self):
           self.beans += 1

       def bean_count(self):
           return self.beans

cannot be dealt with without A addressing the common base class D. And
once it deals with it, A can be broken by reimplementing C without
inheriting it from D:

    class C:
       def __init__(self):
           self.beans = ""

       def add_bean(self):
           self.beans += "o"

       def bean_count(self):
           return len(self.beans)

thus violating encapsulation.


Marko


From steve+comp.lang.python at pearwood.info  Fri Mar 28 10:35:15 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 28 Mar 2014 14:35:15 GMT
Subject: YADTR (Yet Another DateTime Rant)
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
 <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-BD9428.08301128032014@news.panix.com>
Message-ID: <533588a3$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Fri, 28 Mar 2014 08:30:11 -0400, Roy Smith wrote:

> In article <533558fa$0$29994$c3e8da3$5496439d at news.astraweb.com>,
>  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
> 
>> > Yes.  The whole idea of OOD is to decouple internal representation
>> > from external behavior.
>> 
>> The *whole* idea? You don't think that encapsulation and inheritance
>> might also be involved? *wink*
> 
> I'm not sure how "decoupling internal representation from external
> behavior" is substantially different from encapsulation.

They are mostly unrelated. In the first, you're talking about information 
hiding. The second, encapsulation, relates to the bundling of code and 
data, optionally in such a way as to restrict or control access to some 
or all of the encapsulated data.

Encapsulation can be used as a mechanism for information hiding, but need 
not be.

https://en.wikipedia.org/wiki/Encapsulation_%28object-oriented_programming%29


> And, no, I
> don't think inheritance is a fundamental characteristic of OOD, nudge
> nudge.

That's not representative of what most people, and specifically 
most computer scientists, consider fundamental to OOP.

https://en.wikipedia.org/wiki/Object-oriented_programming#Fundamental_features_and_concepts

It's difficult to pin-point exactly what characteristics of OOP are 
fundamental, but inheritance is surely one of them.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From neilc at norwich.edu  Fri Mar 28 11:00:38 2014
From: neilc at norwich.edu (Neil Cerutti)
Date: Fri, 28 Mar 2014 15:00:38 +0000 (UTC)
Subject: Using query parameters subtitution outside of execute()
References: <5335367B.2090604@digitalfantasy.it>
 <lh3ek9$236$1@ger.gmane.org> <533562E3.1000400@digitalfantasy.it>
 <lh3urk$e1g$1@ger.gmane.org> <53358425.5020109@digitalfantasy.it>
Message-ID: <lh42qm$uea$1@ger.gmane.org>

On 2014-03-28, Daniele Forghieri <guru at digitalfantasy.it> wrote:
> The worse is the contrary, when I must use C and I think 'Here
> I use a dictionary, at the end convert it in a list that I sort
> with that key ...' only to realize that I don't have dictionary
> and the list I can use are very less manageable that the ones I
> used in Python ...

C could provide more friendly general purpose containers in its
library, but doesn't. There are some good free ones: glib, for
example.

Cython provides a really nice in-between level.

-- 
Neil Cerutti



From rosuav at gmail.com  Fri Mar 28 11:25:44 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 02:25:44 +1100
Subject: YADTR (Yet Another DateTime Rant)
In-Reply-To: <533588a3$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <roy-142548.20582725032014@news.panix.com>
 <mailman.8593.1395876355.18130.python-list@python.org>
 <53336df8$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh0u51$dj8$1@news.albasani.net>
 <mailman.8613.1395917059.18130.python-list@python.org>
 <roy-E22E44.08522427032014@news.panix.com>
 <5334b747$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-E6F0E7.20291727032014@news.panix.com>
 <533558fa$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-BD9428.08301128032014@news.panix.com>
 <533588a3$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqQr4czkc1_0jm1nOZL-9kOtV289Zw5PHGfmtL4tUp+Cw@mail.gmail.com>

On Sat, Mar 29, 2014 at 1:35 AM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> It's difficult to pin-point exactly what characteristics of OOP are
> fundamental, but inheritance is surely one of them.

I've always understood OOP to be all about binding code and data
together (methods as part of an object, rather than functions
operating on data) - ie polymorphism, such that you say "do this" and
the object knows how its "do this" should be done. That's at least as
important as inheritance IMO.

But yes, it is very hard to pin it down.

ChrisA


From Bernd-Waterkamp at web.de  Fri Mar 28 14:21:21 2014
From: Bernd-Waterkamp at web.de (Bernd Waterkamp)
Date: Fri, 28 Mar 2014 19:21:21 +0100
Subject: CentOS 6.5 / SPEC file
References: <CAEctU6pmKni6f1wd31dUggOHLtwXBt=JeZ4G6Uh10+1n8=5_xg@mail.gmail.com>
 <53349787.3080301@gmail.com>
 <mailman.8638.1395956736.18130.python-list@python.org>
Message-ID: <wno7m3nipf5f$.pyoiklcbglsx.dlg@40tude.net>

Michael Torrie schrieb:

> I should add, that the only correct way to package Python 3 on RHEL 6 is
> by making the package called "python3" or something that won't collide
> with the system Python 2.x package.  

Another option for Fedora and RHEL6: Software Collections 

http://developerblog.redhat.com/2014/02/18/migrate-to-python3-w-rhscl/
https://fedorahosted.org/SoftwareCollections/


From random832 at fastmail.us  Fri Mar 28 14:55:45 2014
From: random832 at fastmail.us (random832 at fastmail.us)
Date: Fri, 28 Mar 2014 14:55:45 -0400
Subject: unicode as valid naming symbols
In-Reply-To: <bbe6f1ef-f6e6-4e3d-9dc3-8b3b66edaf40@googlegroups.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com> <53329549.1000208@rece.vub.ac.be>
 <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>
 <mailman.8607.1395912965.18130.python-list@python.org>
 <bbe6f1ef-f6e6-4e3d-9dc3-8b3b66edaf40@googlegroups.com>
Message-ID: <1396032945.6439.100149669.161EB9FB@webmail.messagingengine.com>

On Thu, Mar 27, 2014, at 11:10, Rustom Mody wrote:
> Just out of curiosity how do/did you type that?
> When I see an exotic denizen from the unicode-universe I paste it into
> emacs and ask "Who are you?"
> 
> But with your 'def' my emacs is going a bit crazy!

Your emacs probably is using UCS-2 or UTF-16. The former can't handle
characters above 65535 at all, the latter stores them as if they were
two characters [so code that's not expecting them will handle them
incorrectly]


From harrismh777 at gmail.com  Fri Mar 28 17:18:25 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 16:18:25 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<10101874-2995-4acd-9851-989603f052e3@googlegroups.com>	<bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>	<e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>	<mailman.8369.1395437459.18130.python-list@python.org>	<a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>	<mailman.8377.1395456097.18130.python-list@python.org>	<dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>	<lgj4sp$7ed$1@speranza.aioe.org>	<532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh4ouu$n8l$1@speranza.aioe.org>

On 3/27/14 7:34 PM, Steven D'Aprano wrote:
 > As for enormous number of users who will have
 > difficulty typing ? in their source code, they certainly don't count!
 > It's good enough that *you* have a solution to that problem, you can type
 > alt-v, and anyone who can't simply doesn't matter.

You have an interesting point here; more interesting perhaps than you know.

We have a unicode system [1] capable of zillions of characters, and most 
of [us] have some qwerty system keyboard [104 keys?] with meta key 
mappings for a few more. Talk about the cart before the horse.

We need a standard input system not controlled by Microsoft where-by 
everyone in the entire world can enter unicode (with customization) 
easily and inexpensively. A unicode keyboard would be nice. Why must 
everyone in the world be stuck with a U.S. Royal typewriter keyboard for 
two or three hundred years? Dvorak had the right idea; but it didn't 
stick (although I have a Dvorak key mapping I use (with emacs) just for 
fun).

I do care, Steven. You'll never ever hear me say "screw" somebody, not 
because I'm holier than thou, but because everyone counts--everyone.

Your point about the biologist is fabulous (my point as well), "I didn't 
study biology for six years to wash test tubes and program computers, 
but it comes with the territory".  Steven, dude, you proved my point 
with that. Most biologists (academics particularly) are studying systems 
that require computers these days--- and the scientists in that field DO 
want to program computers (I didn't say love) and the "want" is 
powerful.  I didn't say that they "liked it" either. Somehow a biologist 
needs to be able to talk to that goofy machine (which they hate) and be 
able to do so efficiently and I dare say rapidly. There needs to be a 
system for them; general, easy, elegant yet comprehensible, flexible yet 
unified, discrete, simplified (without being oversimplified).  wow. Talk 
development requirements.

marcus


[1]  http://www.unicode.org/standard/where/


From harrismh777 at gmail.com  Fri Mar 28 17:56:37 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 16:56:37 -0500
Subject: Howto flaten a list of lists was (Explanation of this Python language
 feature)
Message-ID: <lh4r6h$sqr$1@speranza.aioe.org>

On Fri, Mar 21, 2014 at 1:42 PM, vasudevram <vasudevram at gmail.com> wrote:
 >> Can anyone - maybe one of the Python language core team, or someone 
 >> with knowledge of the internals of Python - can explain why this 
 >> code works, and whether the different occurrences of the name x in 
 >> the expression, are in different scopes or not? :
 >>
 >> x = [[1,2], [3,4], [5,6]]
 >>     [x for x in x for x in x]

 > I'll give this +1 for playfulness, and -2 for lack of clarity.

 > I hope no one thinks this sort of thing is good to do in real-life code.

No. This has to be a better way to flatten lists:

 >>> from functools import reduce

 >>> import operator as ?

 >>> reduce(?.add, l)
[1, 2, 3, 4, 5, 6, 7, 8, 9]

 >>>


marcus


From harrismh777 at gmail.com  Fri Mar 28 18:00:27 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 17:00:27 -0500
Subject: How to flatten a list of lists was (Explanation of this Python
 language feature?)
In-Reply-To: <mailman.8641.1395963929.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8641.1395963929.18130.python-list@python.org>
Message-ID: <5335F0FB.3040904@gmail.com>

On 3/27/14 6:45 PM, Dan Stromberg wrote:
> On Fri, Mar 21, 2014 at 1:42 PM, vasudevram <vasudevram at gmail.com> wrote:
>> Can anyone - maybe one of the Python language core team,
>>or someone with knowledge of the internals of Python - can
>>explain why this code works, and whether the different
>>occurrences of the name x in the expression, are in
>>different scopes or not? :
>>
>> x = [[1,2], [3,4], [5,6]]
>>      [x for x in x for x in x]
>
> I'll give this +1 for playfulness, and -2 for lack of clarity.
>
> I hope no one thinks this sort of thing is good to do in real-life code.
>

You might try this to flatten a list of lists:

 >>> from functools import reduce

 >>> import operator

 >>> import operator as ?

 >>> reduce(?.add, l)

[1, 2, 3, 4, 5, 6, 7, 8, 9]
 >>>


marcus


From harrismh777 at gmail.com  Fri Mar 28 18:00:27 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 17:00:27 -0500
Subject: How to flatten a list of lists was (Explanation of this Python
 language feature?)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8641.1395963929.18130.python-list@python.org>
Message-ID: <5335F0FB.3040904@gmail.com>

On 3/27/14 6:45 PM, Dan Stromberg wrote:
> On Fri, Mar 21, 2014 at 1:42 PM, vasudevram <vasudevram at gmail.com> wrote:
>> Can anyone - maybe one of the Python language core team,
>>or someone with knowledge of the internals of Python - can
>>explain why this code works, and whether the different
>>occurrences of the name x in the expression, are in
>>different scopes or not? :
>>
>> x = [[1,2], [3,4], [5,6]]
>>      [x for x in x for x in x]
>
> I'll give this +1 for playfulness, and -2 for lack of clarity.
>
> I hope no one thinks this sort of thing is good to do in real-life code.
>

You might try this to flatten a list of lists:

 >>> from functools import reduce

 >>> import operator

 >>> import operator as ?

 >>> reduce(?.add, l)

[1, 2, 3, 4, 5, 6, 7, 8, 9]
 >>>


marcus


From harrismh777 at gmail.com  Fri Mar 28 18:05:15 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 17:05:15 -0500
Subject: To flatten a nested list was (Explanation of this Python language
 feature? [x for x in x for x in x]
In-Reply-To: <mailman.8641.1395963929.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8641.1395963929.18130.python-list@python.org>
Message-ID: <5335F21B.1060702@gmail.com>

On 3/27/14 6:45 PM, Dan Stromberg wrote:
>>
>> x = [[1,2], [3,4], [5,6]]
>>      [x for x in x for x in x]
>
> I'll give this +1 for playfulness, and -2 for lack of clarity.
>
> I hope no one thinks this sort of thing is good to do in real-life code.
>

You might try this to flatten a list of lists:

 >>> from functools import reduce

 >>> L = [[1,2,3],[4,5,6],[7],[8,9]]

 >>> import operator as ?

 >>> reduce(?.add, L)
[1, 2, 3, 4, 5, 6, 7, 8, 9]

 >>>


marcus


From harrismh777 at gmail.com  Fri Mar 28 18:05:15 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 17:05:15 -0500
Subject: To flatten a nested list was (Explanation of this Python language
 feature? [x for x in x for x in x]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8641.1395963929.18130.python-list@python.org>
Message-ID: <5335F21B.1060702@gmail.com>

On 3/27/14 6:45 PM, Dan Stromberg wrote:
>>
>> x = [[1,2], [3,4], [5,6]]
>>      [x for x in x for x in x]
>
> I'll give this +1 for playfulness, and -2 for lack of clarity.
>
> I hope no one thinks this sort of thing is good to do in real-life code.
>

You might try this to flatten a list of lists:

 >>> from functools import reduce

 >>> L = [[1,2,3],[4,5,6],[7],[8,9]]

 >>> import operator as ?

 >>> reduce(?.add, L)
[1, 2, 3, 4, 5, 6, 7, 8, 9]

 >>>


marcus


From breamoreboy at yahoo.co.uk  Fri Mar 28 18:12:33 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Fri, 28 Mar 2014 22:12:33 +0000
Subject: Howto flaten a list of lists was (Explanation of this Python
 language feature)
In-Reply-To: <lh4r6h$sqr$1@speranza.aioe.org>
References: <lh4r6h$sqr$1@speranza.aioe.org>
Message-ID: <lh4s4f$4fs$1@ger.gmane.org>

On 28/03/2014 21:56, Mark H Harris wrote:
> On Fri, Mar 21, 2014 at 1:42 PM, vasudevram <vasudevram at gmail.com> wrote:
>  >> Can anyone - maybe one of the Python language core team, or someone
>  >> with knowledge of the internals of Python - can explain why this >>
> code works, and whether the different occurrences of the name x in >>
> the expression, are in different scopes or not? :
>  >>
>  >> x = [[1,2], [3,4], [5,6]]
>  >>     [x for x in x for x in x]
>
>  > I'll give this +1 for playfulness, and -2 for lack of clarity.
>
>  > I hope no one thinks this sort of thing is good to do in real-life code.

Strange, I thought Dan Stromberg wrote the above.
>
> No. This has to be a better way to flatten lists:
>
>  >>> from functools import reduce
>
>  >>> import operator as ?
>
>  >>> reduce(?.add, l)
> [1, 2, 3, 4, 5, 6, 7, 8, 9]
>

Why reinvent yet another way of flattening lists, particulary one that 
doesn't use the far more sensible:-

from operator import add

As for the stupid symbol that you're using, real programmers don't give 
a damn about such things, they prefer writing plain, simple, boring code 
that is easy to read.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From harrismh777 at gmail.com  Fri Mar 28 18:23:51 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 17:23:51 -0500
Subject: Howto flaten a list of lists was (Explanation of this Python
 language feature)
In-Reply-To: <mailman.8676.1396044784.18130.python-list@python.org>
References: <lh4r6h$sqr$1@speranza.aioe.org>
 <mailman.8676.1396044784.18130.python-list@python.org>
Message-ID: <5335F677.20605@gmail.com>

On 3/28/14 5:12 PM, Mark Lawrence wrote:
>>
>> No. This has to be a better way to flatten lists:
>>
>>  >>> from functools import reduce
>>
>>  >>> import operator as ?
>>
>>  >>> reduce(?.add, l)
>> [1, 2, 3, 4, 5, 6, 7, 8, 9]
>>
>
> Why reinvent yet another way of flattening lists, particulary one that
> doesn't use the far more sensible:-

    { particularly }

>
> from operator import add
>
> As for the stupid symbol that you're using, real programmers don't give
> a damn about such things, they prefer writing plain, simple, boring code
> that is easy to read.

:-))    as RMS would say, "playful hacking, dude, playful hacking..."






From harrismh777 at gmail.com  Fri Mar 28 18:23:51 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 17:23:51 -0500
Subject: Howto flaten a list of lists was (Explanation of this Python
 language feature)
References: <lh4r6h$sqr$1@speranza.aioe.org>
 <mailman.8676.1396044784.18130.python-list@python.org>
Message-ID: <5335F677.20605@gmail.com>

On 3/28/14 5:12 PM, Mark Lawrence wrote:
>>
>> No. This has to be a better way to flatten lists:
>>
>>  >>> from functools import reduce
>>
>>  >>> import operator as ?
>>
>>  >>> reduce(?.add, l)
>> [1, 2, 3, 4, 5, 6, 7, 8, 9]
>>
>
> Why reinvent yet another way of flattening lists, particulary one that
> doesn't use the far more sensible:-

    { particularly }

>
> from operator import add
>
> As for the stupid symbol that you're using, real programmers don't give
> a damn about such things, they prefer writing plain, simple, boring code
> that is easy to read.

:-))    as RMS would say, "playful hacking, dude, playful hacking..."






From steve+comp.lang.python at pearwood.info  Fri Mar 28 22:31:36 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 29 Mar 2014 02:31:36 GMT
Subject: To flatten a nested list was (Explanation of this Python
 language feature? [x for x in x for x in x]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8641.1395963929.18130.python-list@python.org>
 <5335F21B.1060702@gmail.com>
Message-ID: <53363088$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Fri, 28 Mar 2014 17:05:15 -0500, Mark H Harris wrote:

> You might try this to flatten a list of lists:

We got that the first four times you posted it. No need for a fifth. 


>  >>> from functools import reduce
>  >>> L = [[1,2,3],[4,5,6],[7],[8,9]]
>  >>> import operator as ?

Why would you name the operator module the Greek letter l? Why not the 
Armenian letter ? (yiwn)? That's pure obfuscation. The operator module has 
nothing to do with "l", and nothing to do with Greek lambda.

This is exactly the sort of foolish obfuscation that opponents warned 
about when Python first introduced support for non-ASCII identifiers.



>  >>> reduce(?.add, L)
> [1, 2, 3, 4, 5, 6, 7, 8, 9]

Furthermore, this is a very inefficient way of flattening a nested list. 
Doubling the size of the list quadruples the time taken; increasing the 
size by a factor of 10 increases the time by a factor of more than 100:


py> from operator import add
py> from functools import reduce
py> L = [[1]]*10000
py> with Stopwatch():  # code for this available on request
...     x = reduce(add, L)
...
time taken: 0.348851 seconds
py> L = [[1]]*100000
py> with Stopwatch():
...     x = reduce(add, L)
...
time taken: 41.344467 seconds



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Fri Mar 28 22:33:06 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 29 Mar 2014 02:33:06 GMT
Subject: Howto flaten a list of lists was (Explanation of this Python
 language feature)
References: <lh4r6h$sqr$1@speranza.aioe.org>
 <mailman.8676.1396044784.18130.python-list@python.org>
 <5335F677.20605@gmail.com>
Message-ID: <533630e2$0$29994$c3e8da3$5496439d@news.astraweb.com>

Mark, please stop posting to the newsgroup comp.lang.python AND the 
mailing list python-list at python.org. They mirror each other. Your posts 
are not so important that we need to see everything twice.


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Fri Mar 28 22:45:12 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 13:45:12 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lh4ouu$n8l$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
Message-ID: <CAPTjJmpXFXGou0vA72g7RDs39UyhQ-Cm4hDMj2XhzzgHPA9=HQ@mail.gmail.com>

On Sat, Mar 29, 2014 at 8:18 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> We have a unicode system [1] capable of zillions of characters, and most of
> [us] have some qwerty system keyboard [104 keys?] with meta key mappings for
> a few more. Talk about the cart before the horse.
>
> We need a standard input system not controlled by Microsoft...

... uhh... how does the QWERTY system demonstrate Microsoft's
control?? There's more than a hundred years of gap between them, and
in the wrong order.

By the way, thanks for telling me what a zillion is. It must be 65536,
because that's the biggest thing Unicode gives us plural of in number
of characters. :)

Considering that we have ten fingers, having 1114112 keys would be
quite impractical. The smallest number of keys to render that many
characters would probably be 21, but it'd be toggling data into a
computer, rather than typing; *every* character would require holding
down a good number of keys. (Or you could go the other way and have
exactly two keys: 1 and 0. Press either 21 times to enter a single
character.) You'd probably need a minimum of several hundred keys to
get something reasonably logical.

Do you really want a keyboard that takes up that much space? Most
people can't efficiently use F1 through F12, much less another hundred
or two hundred keys.

ChrisA


From harrismh777 at gmail.com  Fri Mar 28 23:04:19 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 22:04:19 -0500
Subject: Howto flaten a list of lists was (Explanation of this Python
 language feature)
References: <lh4r6h$sqr$1@speranza.aioe.org>	<mailman.8676.1396044784.18130.python-list@python.org>	<5335F677.20605@gmail.com>
 <533630e2$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh5d7f$9pe$1@speranza.aioe.org>

On 3/28/14 9:33 PM, Steven D'Aprano wrote:
> Mark, please stop posting to the newsgroup comp.lang.python AND the
> mailing list python-list at python.org. They mirror each other. Your posts
> are not so important that we need to see everything twice.

Its not my fault, Steven. Something goofy is going on. My address says 
only comp.lang.python

I have no idea why some of these messages are being duplicated on the 
mailing list. I only post to the news group.

Anyways, sorry.  I'll keep checking this.

regards,



From steve+comp.lang.python at pearwood.info  Fri Mar 28 23:08:15 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 29 Mar 2014 03:08:15 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <mailman.8678.1396061122.18130.python-list@python.org>
Message-ID: <5336391f$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sat, 29 Mar 2014 13:45:12 +1100, Chris Angelico wrote:

> Considering that we have ten fingers, having 1114112 keys would be quite
> impractical. The smallest number of keys to render that many characters
> would probably be 21, but it'd be toggling data into a computer, rather
> than typing; *every* character would require holding down a good number
> of keys. (Or you could go the other way and have exactly two keys: 1 and
> 0. Press either 21 times to enter a single character.)

http://like-a-boss.org/wp-content/uploads/2011/10/supercoder.jpg



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From harrismh777 at gmail.com  Fri Mar 28 23:18:36 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 22:18:36 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <mailman.8678.1396061122.18130.python-list@python.org>
Message-ID: <lh5e27$b73$1@speranza.aioe.org>

On 3/28/14 9:45 PM, Chris Angelico wrote:
> On Sat, Mar 29, 2014 at 8:18 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>> We have a unicode system [1] capable of zillions of characters, and most of
>> [us] have some qwerty system keyboard [104 keys?] with meta key mappings for
>> a few more. Talk about the cart before the horse.
>>
>> We need a standard input system not controlled by Microsoft...
>
> ... uhh... how does the QWERTY system demonstrate Microsoft's
> control?? There's more than a hundred years of gap between them, and
> in the wrong order.

    You know the answer to this question. Does your keyboard have the 
"Windows" emblem|logo on the meta key(s) on lower right, lower left? On 
a standard keyboard its the meta key between ctrl and alt.  Microsoft 
has controlled that meta section of the keyboard for years, effectively 
preventing those keys from being used for unicode meta control keys 
(ironical considering the fact the Microsoft is a major player at the 
unicode consortium).  The meta keyboard on the mac is much more of what 
I have in mind, but that's mac only for now.

> By the way, thanks for telling me what a zillion is. It must be 65536,
> because that's the biggest thing Unicode gives us plural of in number
> of characters. :)

    ha!  :-))   A zillion is 65536 x(several thousand languages). 
Actually I used a zillion because the consortium doesn't even put a 
number on it... because there is a difference between script and 
language, and there are many languages that use Latin. The point is its 
a huge number greater than 128 or 256. (or 104)
>
> Considering that we have ten fingers, having 1114112 keys would be
> quite impractical.

    don't be literal, think meta pages (key mappings) over the actual 
keyboard, but think "standards".

> Do you really want a keyboard that takes up that much space? Most
> people can't efficiently use F1 through F12, much less another hundred
> or two hundred keys.

    No, I want a standard unicode keyboard (a standard specification for 
a unicode keyboard) that facilitates unicode typing with minimal actual 
keys and standard key maps for alternate sets that may be easily 
selected without a mouse and without moving the hands from the home row.

    The mac does a pretty good job of this now, but the mapping editor 
is not built-in; otherwise, the key mappings are very good, quite easy, 
and very fast. But, like Steven pointed out, everyone needs to be on the 
same unicode input device (as standard) before language specs could 
relay on certain code points for tokens | identifiers.

marcus



From rosuav at gmail.com  Fri Mar 28 23:21:46 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 14:21:46 +1100
Subject: Howto flaten a list of lists was (Explanation of this Python
 language feature)
In-Reply-To: <lh5d7f$9pe$1@speranza.aioe.org>
References: <lh4r6h$sqr$1@speranza.aioe.org>
 <mailman.8676.1396044784.18130.python-list@python.org>
 <5335F677.20605@gmail.com>
 <533630e2$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5d7f$9pe$1@speranza.aioe.org>
Message-ID: <CAPTjJmoPcbZds1BB2G6-b50FC_9HkqqNJOnK-unuTXB-zOML8A@mail.gmail.com>

On Sat, Mar 29, 2014 at 2:04 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> Its not my fault, Steven. Something goofy is going on. My address says only
> comp.lang.python

Well, something's causing your messages to come out multiple times and
with different subject lines :)

ChrisA


From rustompmody at gmail.com  Fri Mar 28 23:21:36 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 28 Mar 2014 20:21:36 -0700 (PDT)
Subject: Howto flaten a list of lists was (Explanation of this Python
 language feature)
In-Reply-To: <lh5d7f$9pe$1@speranza.aioe.org>
References: <lh4r6h$sqr$1@speranza.aioe.org>
 <mailman.8676.1396044784.18130.python-list@python.org>
 <5335F677.20605@gmail.com>
 <533630e2$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5d7f$9pe$1@speranza.aioe.org>
Message-ID: <95aa5148-497a-49a1-9e78-2c019c36cf25@googlegroups.com>

On Saturday, March 29, 2014 8:34:19 AM UTC+5:30, Mark H. Harris wrote:
> On 3/28/14 9:33 PM, Steven D'Aprano wrote:
> > Mark, please stop posting to the newsgroup comp.lang.python AND the
> > mailing list (...). They mirror each other. Your posts
> > are not so important that we need to see everything twice.

> Its not my fault, Steven. Something goofy is going on. My address says 
> only comp.lang.python

> I have no idea why some of these messages are being duplicated on the 
> mailing list. I only post to the news group.

> Anyways, sorry.  I'll keep checking this.

> regards,

Just use the amazing, fool-safe, fail-proof google-groups.
And enjoy bliss.

[Uh... And now I need to run... Out of sprinting practice...]


From harrismh777 at gmail.com  Fri Mar 28 23:33:59 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 22:33:59 -0500
Subject: To flatten a nested list was (Explanation of this Python language
 feature? [x for x in x for x in x]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<mailman.8641.1395963929.18130.python-list@python.org>	<5335F21B.1060702@gmail.com>
 <53363088$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh5ev3$cp9$1@speranza.aioe.org>

On 3/28/14 9:31 PM, Steven D'Aprano wrote:
> On Fri, 28 Mar 2014 17:05:15 -0500, Mark H Harris wrote:

>>   >>> from functools import reduce
>>   >>> L = [[1,2,3],[4,5,6],[7],[8,9]]
>>   >>> import operator as ?

>>   >>> reduce(?.add, L)
>> [1, 2, 3, 4, 5, 6, 7, 8, 9]
>
> Furthermore, this is a very inefficient way of flattening a nested list.

    Again, its just another way. Its just playful hacking. The serious 
point behind it ( I am able to do anything I want with the language ), I 
mean that is kinda the whole point. For anyone to actually use my little 
hack they need to know that reduce is in functools (right) then they 
need to understand 'reduce' which is a nightmare, and then they need to 
know why chose the symbol  ?  (which was for no other reason than fun. 
Lastly, they would want to flatten a list without

    [x for x in x for x in x]


:)


    The following is a strawman; YOU build it up, to tear it down/

> py> from operator import add
> py> from functools import reduce
> py> L = [[1]]*10000    <===================  my list didn't have ten thousand items

> py> with Stopwatch():  # code for this available on request
> ...     x = reduce(add, L)
> ...
> time taken: 0.348851 seconds
> py> L = [[1]]*100000    <=============  much less one hundred thousand items
> py> with Stopwatch():
> ...     x = reduce(add, L)
> ...
> time taken: 41.344467 seconds     <====  time is an illusion, ask Einstein/


    (Steven, it was all tongue in cheek, just for fun...  )





From harrismh777 at gmail.com  Fri Mar 28 23:39:01 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 22:39:01 -0500
Subject: Howto flaten a list of lists was (Explanation of this Python
 language feature)
References: <lh4r6h$sqr$1@speranza.aioe.org>
 <mailman.8676.1396044784.18130.python-list@python.org>
 <5335F677.20605@gmail.com>
 <533630e2$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5d7f$9pe$1@speranza.aioe.org>
 <mailman.8679.1396063315.18130.python-list@python.org>
Message-ID: <lh5f8g$d71$1@speranza.aioe.org>

On 3/28/14 10:21 PM, Chris Angelico wrote:
> Well, something's causing your messages to come out multiple times and
> with different subject lines :)

    I changed the subject line ( which I did twice because the first 
post said it had an error and did not post; which apparently was a lie).

    Then I posted again (this time it went without error, but came back 
duplicated.  In any case ONLY the news group was in the to: field. Very 
strange. All of this crap started happening a couple of days back when 
Thunderbird updated their client (I should know better than to accept that).

Anyway, things were supposed to be better once I switched from gg.  uh, huh.

Well, at least the line wrapping thing is fixed.

marcus



From rosuav at gmail.com  Fri Mar 28 23:45:29 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 14:45:29 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lh5e27$b73$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <mailman.8678.1396061122.18130.python-list@python.org>
 <lh5e27$b73$1@speranza.aioe.org>
Message-ID: <CAPTjJmpRaNq9T+NBV8+WX5ipUEfYDmV=E629-GB--aLMx_F1Rg@mail.gmail.com>

On Sat, Mar 29, 2014 at 2:18 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/28/14 9:45 PM, Chris Angelico wrote:
>> ... uhh... how does the QWERTY system demonstrate Microsoft's
>> control?? There's more than a hundred years of gap between them, and
>> in the wrong order.
>
>
>    You know the answer to this question. Does your keyboard have the
> "Windows" emblem|logo on the meta key(s) on lower right, lower left? On a
> standard keyboard its the meta key between ctrl and alt.  Microsoft has
> controlled that meta section of the keyboard for years, effectively
> preventing those keys from being used for unicode meta control keys
> (ironical considering the fact the Microsoft is a major player at the
> unicode consortium).  The meta keyboard on the mac is much more of what I
> have in mind, but that's mac only for now.

No, actually. A lot of my keyboards don't have those, and even those
that do aren't controlled by Microsoft. We've been using those for
other purposes since they first came out. To claim that they indicate
MS control is just as ridiculous as claiming that the Backspace key
indicates control from the Remington Typewriter Company.

>> By the way, thanks for telling me what a zillion is. It must be 65536,
>> because that's the biggest thing Unicode gives us plural of in number
>> of characters. :)
>
>
>    ha!  :-))   A zillion is 65536 x(several thousand languages). Actually I
> used a zillion because the consortium doesn't even put a number on it...
> because there is a difference between script and language, and there are
> many languages that use Latin. The point is its a huge number greater than
> 128 or 256. (or 104)
>
>>
>> Considering that we have ten fingers, having 1114112 keys would be
>> quite impractical.
>
>
>    don't be literal, think meta pages (key mappings) over the actual
> keyboard, but think "standards".

The Unicode standard specifies only 1114112 possible codepoints, of
which only roughly 200K are currently allocated. (And those figures
include non-character codepoints, like the U+D800 to U+DFFF range used
to encode non-BMP codepoints into UTF-16.) So you can't possibly need
any more than that - just over a million - for full Unicode support.
That's standards for you.

>> Do you really want a keyboard that takes up that much space? Most
>> people can't efficiently use F1 through F12, much less another hundred
>> or two hundred keys.
>
>    No, I want a standard unicode keyboard (a standard specification for a
> unicode keyboard) that facilitates unicode typing with minimal actual keys
> and standard key maps for alternate sets that may be easily selected without
> a mouse and without moving the hands from the home row.

Minimal actual keys. Steven almost got it with the link he posted
above, but I can cut one more key off it: if you always press exactly
21 keys to enter one codepoint, you don't need a "Done" key. (But the
"Done" key would allow you to type some characters much more quickly.
You can send a spew of U+0000 just by holding Done, for instance; and
what an accomplishment THAT is in a family man! [1])

>    The mac does a pretty good job of this now, but the mapping editor is not
> built-in; otherwise, the key mappings are very good, quite easy, and very
> fast. But, like Steven pointed out, everyone needs to be on the same unicode
> input device (as standard) before language specs could relay on certain code
> points for tokens | identifiers.

If that idealized Unicode keyboard were worth doing, it would have
been done by now. There are myriad keyboard designs to choose from,
like these:

http://www.thinkgeek.com/brain/whereisit.cgi?t=keyboard

None has the hundreds of keys needed for rapid entry of arbitrary
Unicode codepoints or characters (in theory you could have a key that
creates a full CCS). Why? Because there's no demand for it.

ChrisA

[1] Look up Gilbert & Sullivan's "Ruddigore" for a very similar line
of argument regarding a sailor.


From steve+comp.lang.python at pearwood.info  Fri Mar 28 23:51:04 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 29 Mar 2014 03:51:04 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <10101874-2995-4acd-9851-989603f052e3@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
Message-ID: <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Fri, 28 Mar 2014 16:18:25 -0500, Mark H Harris wrote:

> We need a standard input system not controlled by Microsoft where-by
> everyone in the entire world can enter unicode (with customization)
> easily and inexpensively. A unicode keyboard would be nice.

Under what circumstances do you see yourself needing a keyboard capable 
of typing Hindi?

I don't wish to pay for a keyboard for entering Arabic when I'm never 
going to enter more than two or three Arabic characters at a time. If I 
need to enter an Arabic character, I can use one of many existing virtual 
keyboards. If I decide to learn Arabic, I will use my current keyboard 
(perhaps with new keycaps) and switch to a different keyboard layout.

I don't think that an English-speaker who needs to occasionally enter a 
few characters like ? ? or ?, a mathematician who knows TeX, a Russian 
wanting to type in Cyrillic, and a Japanese writer who needs to swap 
between four different writing systems (Kanji, Hiragana, Katakana, and 
R?maji) are all going to be well-suited by any one system. I expect that 
it will end up being one-size-fits-none.


> Why must
> everyone in the world be stuck with a U.S. Royal typewriter keyboard for
> two or three hundred years? 

You are being patronising to the 94% of the world that is not from the 
USA. Do you honestly think that people all over the world have been using 
computers for 30 or 40 years without any way to enter their native 
language? Before trying to speak for everyone in the world, it would be a 
good idea to learn something about their situation first.

People are not stuck with the US Royal typewriter keyboard. Keyboards are 
localised all over the world. I'm not just talking about European 
keyboards mostly similar to US keyboards but with a few customizations. 
I'm talking about keyboards for entering Chinese and Japanese:

http://www.keysourcechina.com/chinese-keyboard.html
http://www.stanford.edu/class/cs140/projects/pintos/specs/kbd/jp106.jpg

although I'm pretty sure this is a joke:

http://propelsteps.boards.net/thread/27/creative-chinese-keyboard-2000-symbols


When you install Linux, one of the first things the installer asks you to 
do is choose a keyboard layout. The choices are *not* just:

US Qwerty
US Dvorak

but one of a large variety of keyboard layouts. On my system, there are a 
least 95:

[root at ando ~]# ls /usr/share/X11/xkb/symbols | wc -l
95

Likely many more, as most of the files contain more than one layout; e.g. 
the ru file contains 5, the fr file contains 7.

On Mac and Windows, locally-bought systems will come pre-configured for 
the local national language.

You can even buy keycaps for some pretty niche use-cases:

http://www.maxkeyboard.com/r4-1x1-cherry-mx-chinese-astrology-animal-sign-keycap-set.html

although I expect that's more for novelty reasons than anything else.

Most languages work quite well with the standard keyboard layout of four 
rows of keys, plus modifiers and special keys. Japanese and Chinese are 
probably the two hardest cases (apart from languages that don't even have 
a writing system!), and even they have solutions to the problem of 
computer input. (In Japan, many people don't even use Unicode, at least 
not yet, so your hypothetical solution wouldn't help them one bit.)

Virtually all keyboards today have standardized on a similar layout, one 
with at least three modifier keys (and more commonly four). People with 
specialized needs can configure their keyboard the way it suits them. 
There's no need for some dictator or committee to declare that everyone 
will use this system or that. Historians who need to enter Phoenician 
characters can do so, the rest of us don't need to worry about them.

Relevant: https://en.wikipedia.org/wiki/Space-cadet_keyboard


> Dvorak had the right idea; but it didn't
> stick (although I have a Dvorak key mapping I use (with emacs) just for
> fun).

Dvorak is an American English system. There are modified versions to suit 
other languages with additional characters, but it is essentially 
*identical* to Qwerty except for the order that the keys appear. 
Shuffling the order that Latin letters ABC...Z appear on the keyboard is 
not in any way "the right idea" for entering non-Latin languages, nor 
does a Dvorak language help enter arbitrary Unicode characters.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From harrismh777 at gmail.com  Sat Mar 29 00:07:43 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 23:07:43 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>	<e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>	<mailman.8369.1395437459.18130.python-list@python.org>	<a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>	<mailman.8377.1395456097.18130.python-list@python.org>	<dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>	<lgj4sp$7ed$1@speranza.aioe.org>	<532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh5gua$g05$1@speranza.aioe.org>

On 3/28/14 10:51 PM, Steven D'Aprano wrote:

>> Why must
>> everyone in the world be stuck with a U.S. Royal typewriter keyboard for
>> two or three hundred years?
>
> You are being patronising to the 94% of the world that is not from the
> USA. Do you honestly think that people all over the world have been using
> computers for 30 or 40 years without any way to enter their native
> language?

You think ~sooo three dimensionally.

Picture this  ~a unicode keyboard with morphing keytops (digital ink, 
light emitting); a standard layout of keys that are touch sensitive, are 
meta operative, and are able to input *every* language on earth (as well 
any symbol). The keyboard may emit light, but not necessarily. The keys 
may be raised, but not necessarily; they have a glassy feel, soft, 
sensual, and completely programmable. Code point pages (key top mappings 
literally) are selectable on|off screen. The keyboard is obviously 
wireless, and the entire keytopsection is mouse-able; the whole keyboard 
is a pinting device, with diff sections for scrolling &c.

This keyboard will be standard in about 25 years... none exist today.

One of the things I do is biblical and classical language support and 
translation (Latin, Hebrew, and Greek).  I do translation work as well 
as papers, research, &c; I need four full keyboards.  I'm getting by 
fairly well with the macs key mappings, but what I'm really after is the 
21st century keyboard I'm dreaming about above.

Think, virtual keyboard, on a keytoplayout... but separate from any 
touchable screen. And, think mac keytops (or flatter) not the plastic 
IBM typewriter like keyboards of today. Think beyond.

marcus


From ben+python at benfinney.id.au  Sat Mar 29 00:18:30 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sat, 29 Mar 2014 15:18:30 +1100
Subject: Keyboard standards (was: Explanation of this Python language feature?
 [x for x in x for x in x] (to flatten a nested list))
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <mailman.8678.1396061122.18130.python-list@python.org>
 <lh5e27$b73$1@speranza.aioe.org>
Message-ID: <85txahocx5.fsf_-_@benfinney.id.au>

Mark H Harris <harrismh777 at gmail.com> writes:

> > On Sat, Mar 29, 2014 at 8:18 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> >> We need a standard input system not controlled by Microsoft...
>
> [?] Does your keyboard have the "Windows" emblem|logo on the meta
> key(s) on lower right, lower left?

No, mine has a Tux logo, because it was shipped that way from Think
Penguin <URL:https://www.thinkpenguin.com/> and the key you're referring
to operates as the ?Super? key in GNU+Linux. Quite useful.

My desktop keyboard is constructed from the Model M buckling-spring
design <URL:https://en.wikipedia.org/wiki/IBM_Model_M_keyboard>. That
means, among other advantages, that the key caps are designed to be
easily replaceable with parts from different manufacturers.

Model M keyboards are now manufactured in Lexington, USA by Unicomp
<URL:http://pckeyboard.com/page/category/UKBD>. They ship
internationally, which is how I got mine.

Unicomp will happily sell you one in various layouts without the Windows
logo. They can even do a key set with the Ctrl and Caps Lock keys
swapped to where they should be, and the Super key printed with a ?Tux?
logo <URL:http://pckeyboard.com/page/product/LinTuxSet>.

On the inexpensive end, Think Penguin will also happily ship Tux logo
stickers to go on top of the Super key
<URL:https://www.thinkpenguin.com/gnu-linux/tux-super-key-keyboard-sticker>.

(I have no affiliation with Think Penguin nor Unicomp, except as a happy
repeat customer.)

>    No, I want a standard unicode keyboard (a standard specification
> for a unicode keyboard) that facilitates unicode typing with minimal
> actual keys and standard key maps for alternate sets that may be
> easily selected without a mouse and without moving the hands from the
> home row.

I can't help you with that, exactly.

However, I type unicode characters with an Input Method engine called
IBus <URL:https://code.google.com/p/ibus/>, which is now in Gnome
<URL:https://help.gnome.org/misc/release-notes/3.6/i18n-ibus.html.en> as
a standard part of the interface.

I can select various IBus input methods depending on the purpose or
language for which I'm writing, and they make it predictable and
memorable to get the right characters.

-- 
 \         ?I have yet to see any problem, however complicated, which, |
  `\      when you looked at it in the right way, did not become still |
_o__)                                more complicated.? ?Paul Anderson |
Ben Finney



From harrismh777 at gmail.com  Sat Mar 29 00:16:00 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 23:16:00 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>	<mailman.8369.1395437459.18130.python-list@python.org>	<a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>	<mailman.8377.1395456097.18130.python-list@python.org>	<dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>	<lgj4sp$7ed$1@speranza.aioe.org>	<532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5gua$g05$1@speranza.aioe.org>
Message-ID: <lh5hdr$gu0$1@speranza.aioe.org>

On 3/28/14 11:07 PM, Mark H Harris wrote:
> Think, virtual keyboard, on a keytoplayout... but separate from any
> touchable screen. And, think mac keytops (or flatter) not the plastic
> IBM typewriter like keyboards of today. Think beyond.

What if~  when I select my UK standard keytop mappings (from my US 
custom keytop mappings) what if the actual keytops on the keyboard 
"morphed" into UK tops?

Better yes, what if the whole keytopsection could morph into Greek tops?

I am able to type in Greek, well I've been doing it for about 12 years, 
but it would be soooo much better if the keytopsection actually morphed.

marcus



From harrismh777 at gmail.com  Sat Mar 29 00:21:42 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 23:21:42 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>	<mailman.8369.1395437459.18130.python-list@python.org>	<a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>	<mailman.8377.1395456097.18130.python-list@python.org>	<dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>	<lgj4sp$7ed$1@speranza.aioe.org>	<532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5gua$g05$1@speranza.aioe.org> <lh5hdr$gu0$1@speranza.aioe.org>
Message-ID: <lh5hoh$hgt$1@speranza.aioe.org>

On 3/28/14 11:16 PM, Mark H Harris wrote:
> I am able to type in Greek, well I've been doing it for about 12 years,
> but it would be soooo much better if the keytopsection actually morphed.


What if, when you opened your new computer in Botswana, and you selected 
your language in gnu/linux lang setup, and your standard unicode 
keyboard morphed into your favorite Tswana or Setswana { whatever } and 
only ONE keyboard needed to be manufactured ?

re THINK





From harrismh777 at gmail.com  Sat Mar 29 00:26:25 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 23:26:25 -0500
Subject: Keyboard standards
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
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 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
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 <lh5e27$b73$1@speranza.aioe.org>
 <mailman.8681.1396066726.18130.python-list@python.org>
Message-ID: <lh5i1c$ht7$1@speranza.aioe.org>

On 3/28/14 11:18 PM, Ben Finney wrote:

> On the inexpensive end, Think Penguin will also happily ship Tux logo
> stickers to go on top of the Super key
> <URL:https://www.thinkpenguin.com/gnu-linux/tux-super-key-keyboard-sticker>.

That's ~cool. I can now remove that nasty M$ meta key. Actually, I got 
so sick of looking at that goofy little warped window that I grabbed 
myself a magic marker and blacked it out.   :)

marcus


PS   Thunderbird puts *both* the list and the news group addys in the 
to: header field on  reply-to-list.   ~nice, huh.


From harrismh777 at gmail.com  Sat Mar 29 00:40:01 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Fri, 28 Mar 2014 23:40:01 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>	<e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>	<mailman.8369.1395437459.18130.python-list@python.org>	<a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>	<mailman.8377.1395456097.18130.python-list@python.org>	<dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>	<lgj4sp$7ed$1@speranza.aioe.org>	<532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh5iqs$j0m$1@speranza.aioe.org>

On 3/28/14 10:51 PM, Steven D'Aprano wrote:
> You are being patronising to the 94% of the world that is not from the
> USA. Do you honestly think that people all over the world have been using
> computers for 30 or 40 years without any way to enter their native
> language?

uh, pretty much.   That's why they called it ASCII American Standard 
Code for Information Interchange...  yup, pretty much. Worked pretty 
well too, for many many years, because so many languages derive from 
Latin, and most non third world countries use Latin derived character 
sets; yes, although missing dieresis and grave and acute accents, &c.

Specialized keytops are made now, but what if...


Dream


From rosuav at gmail.com  Sat Mar 29 00:48:42 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 15:48:42 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lh5gua$g05$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
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 <lh4ouu$n8l$1@speranza.aioe.org>
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 <lh5gua$g05$1@speranza.aioe.org>
Message-ID: <CAPTjJmpMPUftVA60qymTZUQqbdSRHBBZh9-CVcs8imRk1MqQKQ@mail.gmail.com>

On Sat, Mar 29, 2014 at 3:07 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> You think ~sooo three dimensionally.

Yeah Doc, I have a real problem with that. -- Marty McFly

> Picture this  ~a unicode keyboard with morphing keytops (digital ink, light
> emitting); a standard layout of keys that are touch sensitive, are meta
> operative, and are able to input *every* language on earth (as well any
> symbol). The keyboard may emit light, but not necessarily. The keys may be
> raised, but not necessarily; they have a glassy feel, soft, sensual, and
> completely programmable. Code point pages (key top mappings literally) are
> selectable on|off screen. The keyboard is obviously wireless, and the entire
> keytopsection is mouse-able; the whole keyboard is a pinting device, with
> diff sections for scrolling &c.
>
> This keyboard will be standard in about 25 years... none exist today.

Wrong. You just have to be willing to pay for it.

http://www.thinkgeek.com/product/181d/?srp=14

Or you could just get a blank keytops keyboard and reprogram it how
you like. But hey, have you noticed something? NOT ONE of these ideas
actually makes it easy to write Python code with occasional non-ASCII
characters in it. Switching keyboard mode for a single character is
horribly inefficient, especially if you have to remember a whole lot
of different modes for different characters ("lambda is
meta-butterfly-greek L meta-ctrl-space, and equality is
meta-mathematics 5 meta-ctrl-space"). Putting everything onto a single
keyboard is unworkable. Requiring you to press long key sequences to
generate single characters is useless. (You may as well just press
L-A-M-B-D-A and have it come out as "lambda".) Even with an ideal
keyboard, the creature of your fancies, you won't get past that, for
the same reason that we have keyboards that type letters rather than
English words.

ChrisA


From rustompmody at gmail.com  Sat Mar 29 01:00:49 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 28 Mar 2014 22:00:49 -0700 (PDT)
Subject: unicode as valid naming symbols
In-Reply-To: <mailman.8673.1396032954.18130.python-list@python.org>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com> <53329549.1000208@rece.vub.ac.be>
 <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>
 <mailman.8607.1395912965.18130.python-list@python.org>
 <bbe6f1ef-f6e6-4e3d-9dc3-8b3b66edaf40@googlegroups.com>
 <mailman.8673.1396032954.18130.python-list@python.org>
Message-ID: <a8faddd0-c494-41b9-8334-a2ec780fca61@googlegroups.com>

On Saturday, March 29, 2014 12:25:45 AM UTC+5:30, rand... at fastmail.us wrote:
> On Thu, Mar 27, 2014, at 11:10, Rustom Mody wrote:
> > Just out of curiosity how do/did you type that?
> > When I see an exotic denizen from the unicode-universe I paste it into
> > emacs and ask "Who are you?"
> > But with your 'def' my emacs is going a bit crazy!

> Your emacs probably is using UCS-2 or UTF-16. The former can't handle
> characters above 65535 at all, the latter stores them as if they were
> two characters [so code that's not expecting them will handle them
> incorrectly]

My current diagnosis (with the help of more knowledgeable folks than myself)
is that its a font problem.

There simply doesn't exist a font (or more likely I dont know of) that 
- is readable
- is scaleable
- spans the whole 17*65536 unicode space

At least out here:
- gnu-unifont does not cover things outside BMP
- dejavu seems to have some bugs


From rosuav at gmail.com  Sat Mar 29 01:08:47 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 16:08:47 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lh5iqs$j0m$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
Message-ID: <CAPTjJmpnnFfU5NvbUBxU2uETQ+zva8cBpmmQXvbqdqR=wpBvuQ@mail.gmail.com>

On Sat, Mar 29, 2014 at 3:40 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/28/14 10:51 PM, Steven D'Aprano wrote:
>>
>> You are being patronising to the 94% of the world that is not from the
>> USA. Do you honestly think that people all over the world have been using
>> computers for 30 or 40 years without any way to enter their native
>> language?
>
>
> uh, pretty much.   That's why they called it ASCII American Standard Code
> for Information Interchange...  yup, pretty much. Worked pretty well too,
> for many many years, because so many languages derive from Latin, and most
> non third world countries use Latin derived character sets; yes, although
> missing dieresis and grave and acute accents, &c.

... wow.

Okay. History lesson time.

http://nedbatchelder.com/text/unipain.html
http://en.wikipedia.org/wiki/Code_page

Back before I was born, people were using computers to write messages
that weren't in English. And they managed it, somehow. Can't imagine
how, if all computers work exclusively with seven-bit Latin-derived
character sets.

"Most non-third-world countries use Latin-derived character sets".
Hmm. Let's see. Greece, Russia, China, Japan, Israel, and Egypt are
either third-world or just so insignificant that you can ignore them
and say "most". Yeah, okay, we'll take that as read.

Names are notoriously inaccurate when it comes to internationality.
Ever heard of a place called IHOP? I hadn't, until I started talking
to Americans. What's the difference between "global" and "universal"?
We're clearly taking no notice of Martian languages here, much less
anything outside our solar system. (If humans had non-FTL space travel
five thousand years ago, there could now be colonies all over the
universe, and we wouldn't necessarily even know about them. Those
people would speak languages that can't possibly be Latin-derived;
most likely they'd be derived from Hebrew or Arabic. In the event that
they make contact, we're going to have to allocate some Unicode planes
to them.) "Extended ASCII" is as international as Unicode, just less
standardized.

ChrisA


From rosuav at gmail.com  Sat Mar 29 01:12:28 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 16:12:28 +1100
Subject: unicode as valid naming symbols
In-Reply-To: <a8faddd0-c494-41b9-8334-a2ec780fca61@googlegroups.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com>
 <53329549.1000208@rece.vub.ac.be>
 <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>
 <mailman.8607.1395912965.18130.python-list@python.org>
 <bbe6f1ef-f6e6-4e3d-9dc3-8b3b66edaf40@googlegroups.com>
 <mailman.8673.1396032954.18130.python-list@python.org>
 <a8faddd0-c494-41b9-8334-a2ec780fca61@googlegroups.com>
Message-ID: <CAPTjJmrX+XHV=5FEo-9FKx49MSDpWJ=PXrXG3-Zx__4tCmUS7g@mail.gmail.com>

On Sat, Mar 29, 2014 at 4:00 PM, Rustom Mody <rustompmody at gmail.com> wrote:
> My current diagnosis (with the help of more knowledgeable folks than myself)
> is that its a font problem.
>
> There simply doesn't exist a font (or more likely I dont know of) that
> - is readable
> - is scaleable
> - spans the whole 17*65536 unicode space

For my MUDding, I use a font imaginatively named "Monospace", which
does most of what I want. There are a handful of characters that come
out as the "square with digits inside", but not huge blocks (certainly
not "everything non-BMP" or anything like that). It's fairly readable,
although I don't know about scaling - I run it at 14pt and nowhere
else. Comes with Debian.

ChrisA


From rosuav at gmail.com  Sat Mar 29 01:13:42 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 16:13:42 +1100
Subject: Keyboard standards
In-Reply-To: <lh5i1c$ht7$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <mailman.8678.1396061122.18130.python-list@python.org>
 <lh5e27$b73$1@speranza.aioe.org>
 <mailman.8681.1396066726.18130.python-list@python.org>
 <lh5i1c$ht7$1@speranza.aioe.org>
Message-ID: <CAPTjJmpPhK0D00tTOh-XnHVBSG=KXLGXTi83NoiJrBd2J0EioA@mail.gmail.com>

On Sat, Mar 29, 2014 at 3:26 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/28/14 11:18 PM, Ben Finney wrote:
>
>> On the inexpensive end, Think Penguin will also happily ship Tux logo
>> stickers to go on top of the Super key
>>
>> <URL:https://www.thinkpenguin.com/gnu-linux/tux-super-key-keyboard-sticker>.
>
>
> That's ~cool. I can now remove that nasty M$ meta key. Actually, I got so
> sick of looking at that goofy little warped window that I grabbed myself a
> magic marker and blacked it out.   :)

If Sharpie can oust Microsoft's dominance over your keyboard, it can't
have been very strong dominance to start with...

When I first met Windows keys, I just popped 'em off and left a gap.
Worked fine.

ChrisA


From rustompmody at gmail.com  Sat Mar 29 01:21:50 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 28 Mar 2014 22:21:50 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8683.1396069736.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
Message-ID: <706187e9-0df4-45fa-9f06-c3a1ddd1ae76@googlegroups.com>

On Saturday, March 29, 2014 10:38:47 AM UTC+5:30, Chris Angelico wrote:
> On Sat, Mar 29, 2014 at 3:40 PM, Mark H Harris wrote:
> > On 3/28/14 10:51 PM, Steven D'Aprano wrote:
> >> You are being patronising to the 94% of the world that is not from the
> >> USA. Do you honestly think that people all over the world have been using
> >> computers for 30 or 40 years without any way to enter their native
> >> language?
> > uh, pretty much.   That's why they called it ASCII American Standard Code
> > for Information Interchange...  yup, pretty much. Worked pretty well too,
> > for many many years, because so many languages derive from Latin, and most
> > non third world countries use Latin derived character sets; yes, although
> > missing dieresis and grave and acute accents, &c.

> ... wow.

> Okay. History lesson time.

> http://nedbatchelder.com/text/unipain.html
> http://en.wikipedia.org/wiki/Code_page

> Back before I was born, people were using computers to write messages
> that weren't in English. And they managed it, somehow. Can't imagine
> how, if all computers work exclusively with seven-bit Latin-derived
> character sets.

> "Most non-third-world countries use Latin-derived character sets".
> Hmm. Let's see. Greece, Russia, China, Japan, Israel, and Egypt are
> either third-world or just so insignificant that you can ignore them
> and say "most". Yeah, okay, we'll take that as read.

> Names are notoriously inaccurate when it comes to internationality.
> Ever heard of a place called IHOP? I hadn't, until I started talking
> to Americans. What's the difference between "global" and "universal"?
> We're clearly taking no notice of Martian languages here, much less
> anything outside our solar system. (If humans had non-FTL space travel
> five thousand years ago, there could now be colonies all over the
> universe, and we wouldn't necessarily even know about them. Those
> people would speak languages that can't possibly be Latin-derived;
> most likely they'd be derived from Hebrew or Arabic. In the event that
> they make contact, we're going to have to allocate some Unicode planes
> to them.) "Extended ASCII" is as international as Unicode, just less
> standardized.

> ChrisA

For Indian languages there is usually a specific fully localized
layout and a latin-derived one.

In particular for devanagari, which is directly used (Hindi, Marathi)
or close relative used (Gujarati, Bengali) there is inscript and itrans
https://fedoraproject.org/wiki/I18N/Indic/HindiKeyboardLayouts

itrans is the latin-derived layout, inscript is the fully-localized,
no-relation-to-US-104 one.

I would not be able to use the inscript if I tried and this is true for
most of the people I know even though in some theoretically ergonomic
sense its more efficient.

So in the sphere I am familiar with Mark seems to be right that
ASCII == US-104 rules the planet.

To go from this small-sample data to vast generalizations...
I'll leave to others


From ben+python at benfinney.id.au  Sat Mar 29 01:32:07 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sat, 29 Mar 2014 16:32:07 +1100
Subject: unicode as valid naming symbols
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com>
 <53329549.1000208@rece.vub.ac.be>
 <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>
 <mailman.8607.1395912965.18130.python-list@python.org>
 <bbe6f1ef-f6e6-4e3d-9dc3-8b3b66edaf40@googlegroups.com>
 <mailman.8673.1396032954.18130.python-list@python.org>
 <a8faddd0-c494-41b9-8334-a2ec780fca61@googlegroups.com>
Message-ID: <85ppl5o9ig.fsf@benfinney.id.au>

Rustom Mody <rustompmody at gmail.com> writes:

> At least out here:
> - gnu-unifont does not cover things outside BMP

That implies the GNU Unifont contains no characters from outside the
BMP, which is untrue.

Rather, the GNU Unifont's claim to fame is that it covers all characters
in the BMP. But it does contain many characters outside the BMP.
<URL:http://www.unifoundry.com/unifont.html>

So, I'd re-phrase the above caution more accurately as: The GNU Unifont
has complete coverage of the BMP, and incomplete coverage outside the BMP.

-- 
 \      ?People always ask me, ?Where were you when Kennedy was shot?? |
  `\                        Well, I don't have an alibi.? ?Emo Philips |
_o__)                                                                  |
Ben Finney



From harrismh777 at gmail.com  Sat Mar 29 01:40:43 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 29 Mar 2014 00:40:43 -0500
Subject: Keyboard standards
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <mailman.8678.1396061122.18130.python-list@python.org>
 <lh5e27$b73$1@speranza.aioe.org>
 <mailman.8681.1396066726.18130.python-list@python.org>
 <lh5i1c$ht7$1@speranza.aioe.org>
 <mailman.8685.1396070024.18130.python-list@python.org>
Message-ID: <lh5mcm$osv$1@speranza.aioe.org>

On 3/29/14 12:13 AM, Chris Angelico wrote:
>
> When I first met Windows keys, I just popped 'em off and left a gap.
> Worked fine.

ha!   see.. it popped you off too!   :-))  I found it arrogant to the 
max to place their stupid logo on (my) keyboard. What if every company 
out there wanted "their" own keytop too?  geeze

:)


From harrismh777 at gmail.com  Sat Mar 29 01:51:17 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 29 Mar 2014 00:51:17 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <mailman.8683.1396069736.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
Message-ID: <53365F55.2040302@gmail.com>

On 3/29/14 12:08 AM, Chris Angelico wrote:

>
> Okay. History lesson time.
>

    Tell me what is the lingua franka today?

    Is it,   E n g l i s h ?

    For many many many years people all over the earth were using 
English and ASCII to communicate with early computers... they still are. 
Almost every post on every site is English, and nearly every post on 
every site is a Latin character derivative.

    Kanji and Cyrillic , and Arabic are obvious exceptions to that 
today, mostly because of unicode; NOT extend ASCII.



> Back before I was born, people were using computers to write messages
> that weren't in English.

    No, they weren't... not most... some.

> And they managed it, somehow. Can't imagine
> how, if all computers work exclusively with seven-bit Latin-derived
> character sets.

    Unicode. Shoot, most of the world didn't even have computers until 
just a few years ago; none of the third world did, back in the day, and 
the ones who did communicated in ASCII and English (or some broken 
variant of it).

> "Most non-third-world countries use Latin-derived character sets".

    See this quote from the consortium FAQ:

    >  So, for example, there is only one set of Latin characters
    > defined, despite the fact that the Latin script
    > is used for the alphabets of thousands of different languages.

http://www.unicode.org/faq/basic_q.html#3


marcus



From harrismh777 at gmail.com  Sat Mar 29 01:51:17 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 29 Mar 2014 00:51:17 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
Message-ID: <53365F55.2040302@gmail.com>

On 3/29/14 12:08 AM, Chris Angelico wrote:

>
> Okay. History lesson time.
>

    Tell me what is the lingua franka today?

    Is it,   E n g l i s h ?

    For many many many years people all over the earth were using 
English and ASCII to communicate with early computers... they still are. 
Almost every post on every site is English, and nearly every post on 
every site is a Latin character derivative.

    Kanji and Cyrillic , and Arabic are obvious exceptions to that 
today, mostly because of unicode; NOT extend ASCII.



> Back before I was born, people were using computers to write messages
> that weren't in English.

    No, they weren't... not most... some.

> And they managed it, somehow. Can't imagine
> how, if all computers work exclusively with seven-bit Latin-derived
> character sets.

    Unicode. Shoot, most of the world didn't even have computers until 
just a few years ago; none of the third world did, back in the day, and 
the ones who did communicated in ASCII and English (or some broken 
variant of it).

> "Most non-third-world countries use Latin-derived character sets".

    See this quote from the consortium FAQ:

    >  So, for example, there is only one set of Latin characters
    > defined, despite the fact that the Latin script
    > is used for the alphabets of thousands of different languages.

http://www.unicode.org/faq/basic_q.html#3


marcus



From rosuav at gmail.com  Sat Mar 29 02:03:38 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 29 Mar 2014 17:03:38 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <53365F55.2040302@gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
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Message-ID: <CAPTjJmoODKkg1-EVu+qn7sA4C1aetQF8cUpPdutGDtrTd1=vSQ@mail.gmail.com>

On Sat, Mar 29, 2014 at 4:51 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/29/14 12:08 AM, Chris Angelico wrote:
>
>>
>> Okay. History lesson time.
>>
>
>    Tell me what is the lingua franka today?
>
>    Is it,   E n g l i s h ?
>
>    For many many many years people all over the earth were using English and
> ASCII to communicate with early computers... they still are. Almost every
> post on every site is English, and nearly every post on every site is a
> Latin character derivative.

http://forum.ecomstation.ru/

Prominent discussion forum, although that strives to be at least
partially bilingual in deference to those of us who are so backward as
to speak only English.

>    Kanji and Cyrillic , and Arabic are obvious exceptions to that today,
> mostly because of unicode; NOT extend ASCII.
>
>> Back before I was born, people were using computers to write messages
>> that weren't in English.
>
>
>    No, they weren't... not most... some.

So, pre-Unicode, people didn't use any of those languages or writing
systems with computers, is that what you're saying? That code pages
86x are a total myth?

>> And they managed it, somehow. Can't imagine
>> how, if all computers work exclusively with seven-bit Latin-derived
>> character sets.
>
>
>    Unicode. Shoot, most of the world didn't even have computers until just a
> few years ago; none of the third world did, back in the day, and the ones
> who did communicated in ASCII and English (or some broken variant of it).

Unicode didn't even begin to exist until 1987, and the first version
of the standard wasn't published until 1991. You're seriously saying
that until 1991 (plus however long it took to get implementations into
people's hands) everyone spoke English with computers?!?

>> "Most non-third-world countries use Latin-derived character sets".
>
>
>    See this quote from the consortium FAQ:
>
>    >  So, for example, there is only one set of Latin characters
>    > defined, despite the fact that the Latin script
>    > is used for the alphabets of thousands of different languages.
>
> http://www.unicode.org/faq/basic_q.html#3

Huh?


I'm not sure whether you're trolling or genuinely ignorant of all
history and other languages. Please clarify. If you really are just
trolling, say so, and I'll start ignoring all your posts. You'll make
yourself look less of a fool that way.

ChrisA


From rustompmody at gmail.com  Sat Mar 29 02:10:07 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Fri, 28 Mar 2014 23:10:07 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <53365F55.2040302@gmail.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
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Message-ID: <c5509019-15d1-4578-b62b-e4324e8cefa5@googlegroups.com>

On Saturday, March 29, 2014 11:21:17 AM UTC+5:30, Mark H. Harris wrote:
> On 3/29/14 12:08 AM, Chris Angelico wrote:

> > Okay. History lesson time.

>     Tell me what is the lingua franka today?

>     Is it,   E n g l i s h ?

I wonder Mark, if because you are communicating with your mailing software in
??????? and its expecting unicode (or Kanji)...
you are posting once and we are seeing it twice, thrice...


From metaliobovinus at gmail.com  Sat Mar 29 03:26:12 2014
From: metaliobovinus at gmail.com (Metallicow)
Date: Sat, 29 Mar 2014 00:26:12 -0700 (PDT)
Subject: Embroidermodder2 Kickstarter for Python also!
Message-ID: <b0f03585-e147-4eea-b15f-c8ee54c19d71@googlegroups.com>

Dear Pythoneers,

Just letting you know we got a Kickstarter going on for Embroidermodder2 finally.
We are going to need all the support we can get.
https://www.kickstarter.com/projects/redteam316/embroidermodder-2-for-windows-mac-linux-pi-and-ard

What is the program for you may ask...?
It is for making designs and stuff that can be embroidered on just about any fabric.

It is the first real decent open-source embroidery software that handles many formats that would meet
standard business/artists needs.
https://en.wikipedia.org/wiki/Comparison_of_embroidery_software

As an unofficial developer at this point my involvement hinders in the pure python
side of things, but only upon project success.
So what that means for everyone is that if the project IS successful,
then I will be doing a pure python port of the application also(In PySide/PyQt first, then possibly a wxPy port)
working closely with the two lead developers whom of which I know both well and respect
and can attest to the level of devotion to quality being put into it.
I already have the majority of the GUI code ported at alpha stage ATM so am off to a good start,
but what is needed is at least initial funding before more work on the python side can continue,
because we can't sustain self-funding this forever.
Python bindings is a stretch goal also that was initially set.

I don't recall exactly who it was here that joked about wanting the 
"Guido Van Rossum World Tour" Shirt, but it can be possible for anyone now
with some basic skills and a machine(or you could take it to a local embroidery shop).
    
The program aims to make the designer clothing side of the industry affordable 
and introducable for not only a small fry just starting a business, it also applies to
shops that already exist as it provides open tools easily customizable to meet 
the jobs special purpose needs.

So what we need is for the project to succeed by being funded 
and custom clothing design will then be finally open to the masses and 
so everyone can profit from it.

There are many other rewards to consider also for your pledge.
The campaign is going on until April 20th(Easter), so I encourage everyone interested 
in cheaper quality tools and clothes/etc to pledge what you can.
Lets help these guys out.

Thanks.

Pic to python port WIPz
http://i861.photobucket.com/albums/ab180/metallicow/Python/PySide-PyQt_Port.png


From harrismh777 at gmail.com  Sat Mar 29 04:21:29 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sat, 29 Mar 2014 03:21:29 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
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 <mailman.8688.1396073027.18130.python-list@python.org>
Message-ID: <lh5vq3$c1j$1@speranza.aioe.org>

On 3/29/14 1:03 AM, Chris Angelico wrote:
>
> http://forum.ecomstation.ru/
>
> Prominent discussion forum, although that strives to be at least
> partially bilingual in deference to those of us who are so backward as
> to speak only English.

    Yes. Well, as the joke goes, if you're trilingual you speak three 
languages, if you're bilingual you speak two languages, if you're 
monolingual you're an American (well, that might go for Australia too, 
maybe). When whole continents speak the same language that tends to happen.
>
> So, pre-Unicode, people didn't use any of those languages or writing
> systems with computers, is that what you're saying? That code pages
> 86x are a total myth?

    No, no, no... don't over-read my post please. Think in orders of 
magnitudes. In computer history very little is even mentioned outside 
the U.S.  This is, of course, not fair.  The folks in the U.K. played a 
huge role (the Alan Turing story, The Baby, Blakeley &c). The entire 
world used ASCII, like, forever.  Heck, its still being used!

    Code pages are not a myth,  but they were not prominent, either. And 
of course prejudice is relatively spoken; I don't want to define it.
    What I can tell you in my own experience, as an amateur radio 
operator (W0MHH, general class) who has communicated all over the earth 
(even to Soviet Russia), all my computer|radio comm was in English using 
Morse code sets, Latin characters, and ASCII.  No one ever asked me to 
comm in Russian, or French, nor Italian, nor Tswana...

> Unicode didn't even begin to exist until 1987, and the first version
> of the standard wasn't published until 1991. You're seriously saying
> that until 1991 (plus however long it took to get implementations into
> people's hands) everyone spoke English with computers?!?

    No. see above.   I'm saying that (for the most part) international 
communication has been Latin code pages and ASCII all over the earth, 
until very recently (as you point out).. By the way, in my view, 1991 is 
very recently; from a computer historical standpoint too. I mean, think 
about it, computers have only existed since late 1940s and only in their 
modern context since about 1989. I didn't really start using unicode 
until about 5 years ago; python has only really used it since python3. 
right?

>>     See this quote from the consortium FAQ:
>>
>>     >  So, for example, there is only one set of Latin characters
>>     > defined, despite the fact that the Latin script
>>     > is used for the alphabets of thousands of different languages.
>>
>> http://www.unicode.org/faq/basic_q.html#3
>
> Huh?

    The consortium designates scripts vs. languages. When folks ask them 
about how many languages they support its a difficult answer.  Do you 
mean scripts ( of which there is only one Latin script ) or are you 
referring to the *thousands* of different languages that are scripted in 
Latin characters?  Latin script is used in thousands of languages 
world-wide;  true story.  (that's what the quote is above)

> I'm not sure whether you're trolling or genuinely ignorant of all
> history and other languages.

    Neither.  I never troll, and I'm not ignorant. We are only getting 
cross-ways on this point more because of overlapping time frames I'm 
guessing, and numbers. I know that people groups and various languages 
were being used around the world in pockets for various purposes. I was 
part of the support group at IBM, for instance, that helped with the 
debugging process when we started supporting Kanji on the system36 
system38.  I know that kind of stuff was happening. But when it came to 
communicating world-wide for business (or in my case with radiography) 
it was always ASCII, Latin character sets, and in my case English Morse 
or international Morse code sets (derived from English).


> Please clarify. If you really are just
> trolling, say so, and I'll start ignoring all your posts.

No, Chris.  I never troll.  (that would make my fingers itch)

:)






From ian.g.kelly at gmail.com  Sat Mar 29 06:02:04 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 29 Mar 2014 04:02:04 -0600
Subject: Keyboard standards
In-Reply-To: <lh5mcm$osv$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
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Message-ID: <CALwzid=faZZzyj7JVeWSEZBCjQueN2RVL3CLYNK6Y0QJ2QL7fA@mail.gmail.com>

On Fri, Mar 28, 2014 at 11:40 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> On 3/29/14 12:13 AM, Chris Angelico wrote:
>>
>> When I first met Windows keys, I just popped 'em off and left a gap.
>> Worked fine.
>
> ha!   see.. it popped you off too!   :-))  I found it arrogant to the max to
> place their stupid logo on (my) keyboard. What if every company out there
> wanted "their" own keytop too?  geeze

It's interesting to note that the Command key on Apple keyboards was
originally designed with the Apple logo, but Steve Jobs felt that the
logo was overused by having it plastered all over menu shortcuts, so
they replaced it prior to release with the cloverleaf symbol it now
bears.


From marko at pacujo.net  Sat Mar 29 07:39:08 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 29 Mar 2014 13:39:08 +0200
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <bd158c7b-5511-472c-bce3-cc7b6b7747f6@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
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 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
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Message-ID: <87txahi68z.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> Under what circumstances do you see yourself needing a keyboard capable 
> of typing Hindi?
>
> I don't wish to pay for a keyboard for entering Arabic

Everybody should be able to have a keyboard for their needs. If I should
need an APL keyboard, I would have it in a jiffy.

At the moment, I have a keyboard that is optimized for Python, Finnish,
English, Hebrew and Esperanto. I use it at home and at the office. The
magic is called .Xmodmap.

(But no, I wouldn't name my variables in Hebrew because the next
maintainer might not have a keyboard like mine.)


Marko


From roy at panix.com  Sat Mar 29 07:53:42 2014
From: roy at panix.com (Roy Smith)
Date: Sat, 29 Mar 2014 07:53:42 -0400
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <lgqgn7$bpd$1@speranza.aioe.org>
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 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
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 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87txahi68z.fsf@elektro.pacujo.net>
Message-ID: <roy-94490C.07534229032014@news.panix.com>

In article <87txahi68z.fsf at elektro.pacujo.net>,
 Marko Rauhamaa <marko at pacujo.net> wrote:

> (But no, I wouldn't name my variables in Hebrew because the next
> maintainer might not have a keyboard like mine.)

Have you ever done any work in PHP?  Many of the error messages are 
Hebrew, transliterated into English.  I've gotten many a 
T_PAAMAYIM_NEKUDOTAYIM error.


From marko at pacujo.net  Sat Mar 29 07:59:39 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 29 Mar 2014 13:59:39 +0200
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
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 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <87txahi68z.fsf@elektro.pacujo.net>
 <roy-94490C.07534229032014@news.panix.com>
Message-ID: <87lhvti5as.fsf@elektro.pacujo.net>

Roy Smith <roy at panix.com>:

> Have you ever done any work in PHP? Many of the error messages are
> Hebrew, transliterated into English. I've gotten many a
> T_PAAMAYIM_NEKUDOTAYIM error.

I hate localization. You get a error message in Finnish from "make" or
"grep" and then you try to google it.

So mine is en_US, but I know people who do fi_FI.


Marko


From breamoreboy at yahoo.co.uk  Sat Mar 29 11:45:39 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 29 Mar 2014 15:45:39 +0000
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <lh5vq3$c1j$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
Message-ID: <lh6prh$agk$1@ger.gmane.org>

On 29/03/2014 08:21, Mark H Harris wrote:
>
>     Yes. Well, as the joke goes, if you're trilingual you speak three
> languages, if you're bilingual you speak two languages, if you're
> monolingual you're an American (well, that might go for Australia too,
> maybe). When whole continents speak the same language that tends to happen.

You mean like the USA, where I saw an ad in a shop for a bilingual shop 
assistant?  Or is Spanish so like US English it doesn't count as a 
separate language?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From breamoreboy at yahoo.co.uk  Sat Mar 29 11:46:43 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 29 Mar 2014 15:46:43 +0000
Subject: Howto flaten a list of lists was (Explanation of this Python
 language feature)
In-Reply-To: <95aa5148-497a-49a1-9e78-2c019c36cf25@googlegroups.com>
References: <lh4r6h$sqr$1@speranza.aioe.org>
 <mailman.8676.1396044784.18130.python-list@python.org>
 <5335F677.20605@gmail.com>
 <533630e2$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5d7f$9pe$1@speranza.aioe.org>
 <95aa5148-497a-49a1-9e78-2c019c36cf25@googlegroups.com>
Message-ID: <lh6ptg$agk$2@ger.gmane.org>

On 29/03/2014 03:21, Rustom Mody wrote:
> On Saturday, March 29, 2014 8:34:19 AM UTC+5:30, Mark H. Harris wrote:
>> On 3/28/14 9:33 PM, Steven D'Aprano wrote:
>>> Mark, please stop posting to the newsgroup comp.lang.python AND the
>>> mailing list (...). They mirror each other. Your posts
>>> are not so important that we need to see everything twice.
>
>> Its not my fault, Steven. Something goofy is going on. My address says
>> only comp.lang.python
>
>> I have no idea why some of these messages are being duplicated on the
>> mailing list. I only post to the news group.
>
>> Anyways, sorry.  I'll keep checking this.
>
>> regards,
>
> Just use the amazing, fool-safe, fail-proof google-groups.
> And enjoy bliss.
>
> [Uh... And now I need to run... Out of sprinting practice...]
>

Blast, you beat me to it, and I never could sprint :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From none at mailinator.com  Sat Mar 29 11:59:50 2014
From: none at mailinator.com (mm0fmf)
Date: Sat, 29 Mar 2014 15:59:50 +0000
Subject: Howto flaten a list of lists was (Explanation of this Python
 language feature)
In-Reply-To: <mailman.8676.1396044784.18130.python-list@python.org>
References: <lh4r6h$sqr$1@speranza.aioe.org>
 <mailman.8676.1396044784.18130.python-list@python.org>
Message-ID: <36CZu.66087$o%7.5864@fx29.am4>

On 28/03/2014 22:12, Mark Lawrence wrote:
> As for the stupid symbol that you're using, real programmers don't give
> a damn about such things, they prefer writing plain, simple, boring code
> that is easy to read

What he said.




From steve+comp.lang.python at pearwood.info  Sat Mar 29 12:03:11 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 29 Mar 2014 16:03:11 GMT
Subject: Keyboard standards
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <mailman.8678.1396061122.18130.python-list@python.org>
 <lh5e27$b73$1@speranza.aioe.org>
 <mailman.8681.1396066726.18130.python-list@python.org>
 <lh5i1c$ht7$1@speranza.aioe.org>
 <mailman.8685.1396070024.18130.python-list@python.org>
 <lh5mcm$osv$1@speranza.aioe.org>
Message-ID: <5336eebe$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sat, 29 Mar 2014 00:40:43 -0500, Mark H Harris wrote:

> On 3/29/14 12:13 AM, Chris Angelico wrote:
>>
>> When I first met Windows keys, I just popped 'em off and left a gap.
>> Worked fine.
> 
> ha!   see.. it popped you off too!   :-))  I found it arrogant to the
> max to place their stupid logo on (my) keyboard. 

My keyboard has IBM's logo on it. My keyboard at work has Dell's logo on 
it. In the cupboard, I have a Mac with Apple's logo on it. Do you have a 
problem with that?


> What if every company
> out there wanted "their" own keytop too?  geeze

They're welcome to try. Without support from the operating system, what 
good do you think it will do?

Apple used to have an Apple key. Later they changed it to ? (Command), 
but everyone knows that ? is only available on Apple keyboards.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From gheskett at wdtv.com  Sat Mar 29 13:48:34 2014
From: gheskett at wdtv.com (Gene Heskett)
Date: Sat, 29 Mar 2014 13:48:34 -0400
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <87lhvti5as.fsf@elektro.pacujo.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <roy-94490C.07534229032014@news.panix.com>
 <87lhvti5as.fsf@elektro.pacujo.net>
Message-ID: <201403291348.34617.gheskett@wdtv.com>

On Saturday 29 March 2014 13:47:13 Marko Rauhamaa did opine:

> Roy Smith <roy at panix.com>:
> > Have you ever done any work in PHP? Many of the error messages are
> > Hebrew, transliterated into English. I've gotten many a
> > T_PAAMAYIM_NEKUDOTAYIM error.
> 
> I hate localization. You get a error message in Finnish from "make" or
> "grep" and then you try to google it.
> 
> So mine is en_US, but I know people who do fi_FI.
> 
> 
> Marko

I don't hate it at all.  If, by reporting the error in the persons 1st 
language, he learns faster, that is a huge plus to me.

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>



From gheskett at wdtv.com  Sat Mar 29 13:46:12 2014
From: gheskett at wdtv.com (Gene Heskett)
Date: Sat, 29 Mar 2014 13:46:12 -0400
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <roy-94490C.07534229032014@news.panix.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <87txahi68z.fsf@elektro.pacujo.net>
 <roy-94490C.07534229032014@news.panix.com>
Message-ID: <201403291346.12731.gheskett@wdtv.com>

On Saturday 29 March 2014 13:12:06 Roy Smith did opine:

> In article <87txahi68z.fsf at elektro.pacujo.net>,
> 
>  Marko Rauhamaa <marko at pacujo.net> wrote:
> > (But no, I wouldn't name my variables in Hebrew because the next
> > maintainer might not have a keyboard like mine.)
> 
> Have you ever done any work in PHP?  Many of the error messages are
> Hebrew, transliterated into English.  I've gotten many a
> T_PAAMAYIM_NEKUDOTAYIM error.

Ok, I'll bite, does that have an American English translation?

We did the majority of our web page at WDTV in the earlier years from a 
server we wrote in ARexx running PHP scripts on a souped up Amiga, (we 
farmed it out about the time we made the digital switch because Jim no 
longer had the time to do it full time, and of course the farmed out 
version sucks) but while that wasn't my forte, I don't recall Jim ever 
mentioning PHP error messages as being in Hebrew.

I recall from a mailing list discussion about why English was the dominant 
language, probably a decade or more back up the log so it is not in my 
email corpus now, and a Turkish professor of one of the other latin 
languages nailed it at the time. In terms of the language moving to keep up 
with the state of the art, English moves, rapidly and smoothly and our 
dictionaries are updated to add the new words at many times the pace of the 
older languages.

Some progress is being made of course, we now have what, 18 language linux 
can speak, I'd assume with a certain amount of kicking and screaming, but 
it seems to me that it is still pretty true. Engrish, as exported from 
Japan in their tech manuals doesn't count, we can usually figure out what 
the Sony engineers were trying to say.

Not that it will be appreciated by those younger English speakers here, 
who, because their schools failed them, never got any phonetic tutoring.  I 
did, and as I approach my 80th birthday, I truly feel like the last of a 
dying breed because they dropped that from the elementary school curriculum 
a year later.  That loss, to the language as a whole, is very telling in 
what one hears being spoken on the streets of small town America today, 
much of which would have earned me an F back in the 1940's.  Today, saying 
that the language has been butchered, gives the skilled butcher a bad 
reputation.  But we muddle along, somehow managing to survive all those 
legal warnings on a bottle of aspirin. :)

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>



From steve+comp.lang.python at pearwood.info  Sat Mar 29 13:53:28 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 29 Mar 2014 17:53:28 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <e2b2b9d5-56bd-4455-b8c3-205000d9acb3@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
Message-ID: <53370898$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Fri, 28 Mar 2014 23:40:01 -0500, Mark H Harris wrote:

> On 3/28/14 10:51 PM, Steven D'Aprano wrote:
>> You are being patronising to the 94% of the world that is not from the
>> USA. Do you honestly think that people all over the world have been
>> using computers for 30 or 40 years without any way to enter their
>> native language?
> 
> uh, pretty much.

Then be educated. That is not the case.

People have had localised code pages, and localised keyboards to enter 
characters in those code pages, for up to 30 years, if not longer.

In some of those cases, the localisation was done by companies like IBM, 
Microsoft and Apple, realising that if they wanted to sell computers 
outside of the US, they needed to supply computers that were localised to 
their market. In other cases, it was the national governments of the 
nations which set up their own standards, then insisted that computer 
vendors supported them.

This code page system actually worked pretty well, so long as you only 
exchange documents with people using the same code page. Until the 
Internet, that was mostly the case.


> That's why they called it ASCII American Standard
> Code for Information Interchange...

Yes. So what? Just because ASCII exists doesn't mean everyone uses it 
*exclusively*.

With the demise of EBCDIC as the standard character encoding (actually 
plural encodings, because EBCDIC has code pages too), ASCII has become 
the lowest common denominator for most (but not all) character sets. Pre-
Unicode, most (but definitely not all!) code pages were based on ASCII, 
either with a few changes, or extending it to a full 8 bits.

But that's the point: most people with access to computing in the first 
place, also had access to input methods and code pages for their native 
language. Your idea that they were forced to use ASCII exclusively, with 
no way of entering their own language, is simply wrong.


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From contact.trigon at gmail.com  Sat Mar 29 14:56:50 2014
From: contact.trigon at gmail.com (contact.trigon at gmail.com)
Date: Sat, 29 Mar 2014 11:56:50 -0700 (PDT)
Subject: checking if two things do not equal None
Message-ID: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>

if (a, b) != (None, None):
or
if a != None != b:

Preference? Pros? Cons? Alternatives?

:D


From steve+comp.lang.python at pearwood.info  Sat Mar 29 15:05:03 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 29 Mar 2014 19:05:03 GMT
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
Message-ID: <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sat, 29 Mar 2014 11:56:50 -0700, contact.trigon wrote:

> if (a, b) != (None, None):
> or
> if a != None != b:
> 
> Preference? Pros? Cons? Alternatives?

Do you actually want to check for arbitrary objects which may claim to 
equal None, or do you want to check for objects which are None?


Nearly always when people test for == to None, they don't really mean it. 
They actually want to use an identity test. I'm going to assume the same 
holds here.

if not (a is b is None): ...


Or if you prefer:

if a is not b is not None: ...




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From lele at metapensiero.it  Sat Mar 29 15:24:32 2014
From: lele at metapensiero.it (Lele Gaifax)
Date: Sat, 29 Mar 2014 20:24:32 +0100
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87mwg8yfin.fsf@nautilus.nautilus>

Steven D'Aprano <steve+comp.lang.python at pearwood.info> writes:

> if not (a is b is None): ...
>
> Or if you prefer:
>
> if a is not b is not None: ...

>>> 1 is not 1 is not None
False

So definitely the former!

ciao, lele.
-- 
nickname: Lele Gaifax | Quando vivr? di quello che ho pensato ieri
real: Emanuele Gaifas | comincer? ad aver paura di chi mi copia.
lele at metapensiero.it  |                 -- Fortunato Depero, 1929.



From contact.trigon at gmail.com  Sat Mar 29 15:23:25 2014
From: contact.trigon at gmail.com (contact.trigon at gmail.com)
Date: Sat, 29 Mar 2014 12:23:25 -0700 (PDT)
Subject: checking if two things do not equal None
In-Reply-To: <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <54f5af7c-a069-4452-b49d-881de94ec1cf@googlegroups.com>

> Do you actually want to check for arbitrary objects which may claim to  
> equal None, or do you want to check for objects which are None?

Arbitrary objects are not a concern.

> if not (a is b is None): ...
> 
> if a is not b is not None: ...

Thanks for the examples.



From orgnut at yahoo.com  Sat Mar 29 15:27:12 2014
From: orgnut at yahoo.com (Larry Hudson)
Date: Sat, 29 Mar 2014 12:27:12 -0700
Subject: Keyboard standards
In-Reply-To: <lh5i1c$ht7$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <mailman.8678.1396061122.18130.python-list@python.org>
 <lh5e27$b73$1@speranza.aioe.org>
 <mailman.8681.1396066726.18130.python-list@python.org>
 <lh5i1c$ht7$1@speranza.aioe.org>
Message-ID: <zLydnTn3Y7oMg6rOnZ2dnUVZ_rWdnZ2d@giganews.com>

On 03/28/2014 09:26 PM, Mark H Harris wrote:
>
> PS   Thunderbird puts *both* the list and the news group addys in the to: header field on
> reply-to-list.   ~nice, huh.

Must be the way YOU set it up.  MY Thunderbird (currently version 24.4.0 on Mint Linux 16) 
doesn't do any such thing.  Besides, "Reply" sends private e-mail to the poster -- "Followup" 
sends to the newsgroup.

      -=- Larry -=-



From torriem at gmail.com  Sat Mar 29 15:41:30 2014
From: torriem at gmail.com (Michael Torrie)
Date: Sat, 29 Mar 2014 13:41:30 -0600
Subject: Keyboard standards
In-Reply-To: <zLydnTn3Y7oMg6rOnZ2dnUVZ_rWdnZ2d@giganews.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <mailman.8678.1396061122.18130.python-list@python.org>
 <lh5e27$b73$1@speranza.aioe.org>
 <mailman.8681.1396066726.18130.python-list@python.org>
 <lh5i1c$ht7$1@speranza.aioe.org>
 <zLydnTn3Y7oMg6rOnZ2dnUVZ_rWdnZ2d@giganews.com>
Message-ID: <533721EA.4090903@gmail.com>

On 03/29/2014 01:27 PM, Larry Hudson wrote:
> On 03/28/2014 09:26 PM, Mark H Harris wrote:
>>
>> PS   Thunderbird puts *both* the list and the news group addys in the to: header field on
>> reply-to-list.   ~nice, huh.
> 
> Must be the way YOU set it up.  MY Thunderbird (currently version 24.4.0 on Mint Linux 16) 
> doesn't do any such thing.  Besides, "Reply" sends private e-mail to the poster -- "Followup" 
> sends to the newsgroup.

No, Mark describes the standard way Thunderbird works.  Reply-to-List
does what he says it does. Not sure why your installation works
differently.  I guess maybe you are talking about something different.
The mailing list vs the NNTP list.



From dfnsonfsduifb at gmx.de  Sat Mar 29 17:01:24 2014
From: dfnsonfsduifb at gmx.de (Johannes Bauer)
Date: Sat, 29 Mar 2014 22:01:24 +0100
Subject: checking if two things do not equal None
In-Reply-To: <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh7cb4$ntu$2@news.albasani.net>

On 29.03.2014 20:05, Steven D'Aprano wrote:
> On Sat, 29 Mar 2014 11:56:50 -0700, contact.trigon wrote:
> 
>> if (a, b) != (None, None):
>> or
>> if a != None != b:
>>
>> Preference? Pros? Cons? Alternatives?
>
> if not (a is b is None): ...
> 
> Or if you prefer:
> 
> if a is not b is not None: ...

Is this an obfuscated coding contest? Why do you opt for a solution that
one has to at least think 2 seconds about when the simplest solution:

if (a is not None) or (b is not None):

is immediately understandable by everyone?

Cheers,
Johannes

-- 
>> Wo hattest Du das Beben nochmal GENAU vorhergesagt?
> Zumindest nicht ?ffentlich!
Ah, der neueste und bis heute genialste Streich unsere gro?en
Kosmologen: Die Geheim-Vorhersage.
 - Karl Kaos ?ber R?diger Thomas in dsa <hidbv3$om2$1 at speranza.aioe.org>


From roy at panix.com  Sat Mar 29 17:07:20 2014
From: roy at panix.com (Roy Smith)
Date: Sat, 29 Mar 2014 17:07:20 -0400
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
Message-ID: <roy-B5E8CC.17072029032014@news.panix.com>

In article <lh7cb4$ntu$2 at news.albasani.net>,
 Johannes Bauer <dfnsonfsduifb at gmx.de> wrote:

> On 29.03.2014 20:05, Steven D'Aprano wrote:
> > On Sat, 29 Mar 2014 11:56:50 -0700, contact.trigon wrote:
> > 
> >> if (a, b) != (None, None):
> >> or
> >> if a != None != b:
> >>
> >> Preference? Pros? Cons? Alternatives?
> >
> > if not (a is b is None): ...
> > 
> > Or if you prefer:
> > 
> > if a is not b is not None: ...
> 
> Is this an obfuscated coding contest? Why do you opt for a solution that
> one has to at least think 2 seconds about when the simplest solution:
> 
> if (a is not None) or (b is not None):
> 
> is immediately understandable by everyone?

I agree with that.  But

> if (a, b) != (None, None):

seems pretty straight-forward to me too.  In fact, if anything, it seems 
easier to understand than

> if (a is not None) or (b is not None):

I certainly agree that things like

> if a is not b is not None: ...

belong in an obfuscated coding contest.  Code gets read a lot more often 
than it get written.  Make it dead-ass simple to understand, and future 
generations of programmers who inherit your code will thank you for it.


From davea at davea.name  Sat Mar 29 17:26:57 2014
From: davea at davea.name (Dave Angel)
Date: Sat, 29 Mar 2014 17:26:57 -0400 (EDT)
Subject: Keyboard standards
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <mailman.8678.1396061122.18130.python-list@python.org>
 <lh5e27$b73$1@speranza.aioe.org>
 <mailman.8681.1396066726.18130.python-list@python.org>
 <lh5i1c$ht7$1@speranza.aioe.org>
 <zLydnTn3Y7oMg6rOnZ2dnUVZ_rWdnZ2d@giganews.com>
Message-ID: <lh7dh6$f8s$1@ger.gmane.org>

 Larry Hudson <orgnut at yahoo.com> Wrote in message:
> On 03/28/2014 09:26 PM, Mark H Harris wrote:
>>
>> PS   Thunderbird puts *both* the list and the news group addys in the to: header field on
>> reply-to-list.   ~nice, huh.
> 
> Must be the way YOU set it up.  MY Thunderbird (currently version 24.4.0 on Mint Linux 16) 
> doesn't do any such thing.  Besides, "Reply" sends private e-mail to the poster -- "Followup" 
> sends to the newsgroup.
> 
>       -=- Larry -=-
> 
> 

That depends on whether you're using Thunderbird as a newsreader, 
 or Thunderbird with the mailing list.  Mark Harris is apparently
 doing the latter. 

-- 
DaveA



From davea at davea.name  Sat Mar 29 18:01:03 2014
From: davea at davea.name (Dave Angel)
Date: Sat, 29 Mar 2014 18:01:03 -0400 (EDT)
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
Message-ID: <lh7fh5$803$1@ger.gmane.org>

 Roy Smith <roy at panix.com> Wrote in message:
> In article <lh7cb4$ntu$2 at news.albasani.net>,
>  Johannes Bauer <dfnsonfsduifb at gmx.de> wrote:
> 
>> On 29.03.2014 20:05, Steven D'Aprano wrote:
>> > On Sat, 29 Mar 2014 11:56:50 -0700, contact.trigon wrote:
>> > 
>> >> if (a, b) != (None, None):
>> >> or
>> >> if a != None != b:
>> >>
>> >> Preference? Pros? Cons? Alternatives?
>> >
>> > if not (a is b is None): ...
>> > 
>> > Or if you prefer:
>> > 
>> > if a is not b is not None: ...
>> 
>> Is this an obfuscated coding contest? Why do you opt for a solution that
>> one has to at least think 2 seconds about when the simplest solution:
>> 
>> if (a is not None) or (b is not None):
>> 
>> is immediately understandable by everyone?
> 
> I agree with that.  But
> 
>> if (a, b) != (None, None):
> 
> seems pretty straight-forward to me too.  In fact, if anything, it seems 
> easier to understand than
> 
>> if (a is not None) or (b is not None):
> 
> I certainly agree that things like
> 
>> if a is not b is not None: ...
> 
> belong in an obfuscated coding contest.  Code gets read a lot more often 
> than it get written.  Make it dead-ass simple to understand, and future 
> generations of programmers who inherit your code will thank you for it.
> 

The other advantage to keeping it simple is it's more than likely
 to be right.  If we take the original form as the spec, we'll
 find that two of the alternatives are not even equivalent.
 

def trigon1(a, b):
    return (a,b) != (None, None)  #master

def trigon2(a, b):
    return a != None != b.  #    different

def steven1(a, b):
    return not(a is b is None)

def steven2(a, b):
    return a is not b is not None  #different

def johannes(a, b):
    return (a is not None) or (b is not None)

table = [
trigon1,
trigon2,
steven1,
steven2,
johannes
]

for func in table:
    print func.__name__
    print func(None, None), func(None, 42), func(42, None),
 func(42, 42), func(42, "never")




-- 
DaveA



From dfnsonfsduifb at gmx.de  Sat Mar 29 17:55:12 2014
From: dfnsonfsduifb at gmx.de (Johannes Bauer)
Date: Sat, 29 Mar 2014 22:55:12 +0100
Subject: checking if two things do not equal None
In-Reply-To: <roy-B5E8CC.17072029032014@news.panix.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
Message-ID: <lh7fg0$u6a$1@news.albasani.net>

On 29.03.2014 22:07, Roy Smith wrote:

> I agree with that.  But
> 
>> if (a, b) != (None, None):
> 
> seems pretty straight-forward to me too.  In fact, if anything, it seems 
> easier to understand than
> 
>> if (a is not None) or (b is not None):

Yes, probably. I liked the original, too. If I were writing the code,
I'd probably try to aim to invert the condition though and simply do

if (a is None) and (b is None)

Which is pretty easy to understand for even a rookie programmer.

> I certainly agree that things like
> 
>> if a is not b is not None: ...
> 
> belong in an obfuscated coding contest.  Code gets read a lot more often 
> than it get written.  Make it dead-ass simple to understand, and future 
> generations of programmers who inherit your code will thank you for it.

Absolutely.

Cheers,
Johannes

-- 
>> Wo hattest Du das Beben nochmal GENAU vorhergesagt?
> Zumindest nicht ?ffentlich!
Ah, der neueste und bis heute genialste Streich unsere gro?en
Kosmologen: Die Geheim-Vorhersage.
 - Karl Kaos ?ber R?diger Thomas in dsa <hidbv3$om2$1 at speranza.aioe.org>


From rosuav at gmail.com  Sat Mar 29 18:01:57 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 30 Mar 2014 09:01:57 +1100
Subject: unicode as valid naming symbols
In-Reply-To: <6d2ej9hve7v7m3jfbre1jn9v1loacfr8lo@4ax.com>
References: <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com>
 <53329549.1000208@rece.vub.ac.be>
 <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>
 <mailman.8607.1395912965.18130.python-list@python.org>
 <bbe6f1ef-f6e6-4e3d-9dc3-8b3b66edaf40@googlegroups.com>
 <mailman.8673.1396032954.18130.python-list@python.org>
 <a8faddd0-c494-41b9-8334-a2ec780fca61@googlegroups.com>
 <6d2ej9hve7v7m3jfbre1jn9v1loacfr8lo@4ax.com>
Message-ID: <CAPTjJmryWJ9FZVgjaAUoCqR6o92XYSfufXNtw_YK5vhohPquQA@mail.gmail.com>

On Sun, Mar 30, 2014 at 5:11 AM, Dennis Lee Bieber
<wlfraed at ix.netcom.com> wrote:
>         Considering that a 5x8 bitmap font (which is unlikely to even have
> enough pixels to produce even 65536 unique glyphs) would take 5.6MB for
> your (17*65536), I wouldn't want to see what an algorithmic description
> would require.
>
>         Looking at some of my collection of fonts, TTF and some PS, seem to be
> running around 100kB per font, and those fonts likely have around 128-192
> glyphs.
>
>         For 1114112 glyphs (17*65536) at, say 164 glyphs pre 100kB gives 680MB
> per FONT. Assume the standards: normal, bold, italic, bold-italic -- one is
> now up to 2.7GB per typeface. 5.4GB to support just one serif and one sans
> serif typeface.

Most fonts these days are vector, not bitmap, but a 5x8 bitmap has
forty pixels, any of which can be either on or off - that gives
roughly twice as much data space as the 21-bit Unicode spec. Plenty of
room for 17*65536 unique glyphs. But you're right that it'd then take
~5-6MB to store that, minimum.

ChrisA


From dfnsonfsduifb at gmx.de  Sat Mar 29 18:02:29 2014
From: dfnsonfsduifb at gmx.de (Johannes Bauer)
Date: Sat, 29 Mar 2014 23:02:29 +0100
Subject: checking if two things do not equal None
In-Reply-To: <lh7fg0$u6a$1@news.albasani.net>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <lh7fg0$u6a$1@news.albasani.net>
Message-ID: <lh7ftm$vds$1@news.albasani.net>

On 29.03.2014 22:55, Johannes Bauer wrote:

>>> if (a is not None) or (b is not None):
> 
> Yes, probably. I liked the original, too. If I were writing the code,
> I'd probably try to aim to invert the condition though and simply do
> 
> if (a is None) and (b is None)
> 
> Which is pretty easy to understand for even a rookie programmer.

Let me expand on that thought one or two more sentences: Although it may
seem really trivial, inversions ("not") in my opinion can really make
code unreadable. One thing that I regularly see when peer-reviewing code
is something like:

if not feature_disabled:

or one that I've seen in-field (modulo the programming language and the
variable names):

if (not no_delayed_commit) and (not data_unchanged):

instead of:

if immediate_commit and data_changed:

Enough of my two cents for today :-)
Cheers,
Johannes


-- 
>> Wo hattest Du das Beben nochmal GENAU vorhergesagt?
> Zumindest nicht ?ffentlich!
Ah, der neueste und bis heute genialste Streich unsere gro?en
Kosmologen: Die Geheim-Vorhersage.
 - Karl Kaos ?ber R?diger Thomas in dsa <hidbv3$om2$1 at speranza.aioe.org>


From python.list at tim.thechases.com  Sat Mar 29 18:36:55 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Sat, 29 Mar 2014 17:36:55 -0500
Subject: checking if two things do not equal None
In-Reply-To: <roy-B5E8CC.17072029032014@news.panix.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
Message-ID: <20140329173655.4022d715@bigbox.christie.dr>

On 2014-03-29 17:07, Roy Smith wrote:
> > if (a is not None) or (b is not None):
> > 
> > is immediately understandable by everyone?  
> 
> I agree with that.  But
> 
> > if (a, b) != (None, None):  
> 
> seems pretty straight-forward to me too.  In fact, if anything, it
> seems easier to understand than

And for cases where you have more than one or two things to test for
None-itude, you could use

  if all(x is None for x in [a, b, c, d]):
    do_something_if_theyre_all_None()

or

  if all(x is not None for x in [a, b, c, d]):
    do_something_if_no_Nones()

or

  if not any(x is None for x in [a, b, c, d]):
    do_something_if_no_Nones()

which I find *much* more readable from a maintenance point of view.

-tkc





From roy at panix.com  Sat Mar 29 18:41:03 2014
From: roy at panix.com (Roy Smith)
Date: Sat, 29 Mar 2014 18:41:03 -0400
Subject: checking if two things do not equal None
In-Reply-To: <20140329173655.4022d715@bigbox.christie.dr>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <20140329173655.4022d715@bigbox.christie.dr>
Message-ID: <F5F2BC07-AD55-46F1-970A-5BC49622677A@panix.com>

On Mar 29, 2014, at 6:36 PM, Tim Chase wrote:

> And for cases where you have more than one or two things to test for
> None-itude, you could use
> 
>  if all(x is None for x in [a, b, c, d]):
>    do_something_if_theyre_all_None()

I might have written that as:

if set([a, b, c, d]) == set(None)

That's even clearer if you happen to already have the items in an iterable:

if set(conditions) == set(None)


--
Roy Smith
roy at panix.com



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From tim at thechases.com  Sat Mar 29 18:46:53 2014
From: tim at thechases.com (Tim Chase)
Date: Sat, 29 Mar 2014 17:46:53 -0500
Subject: checking if two things do not equal None
In-Reply-To: <F5F2BC07-AD55-46F1-970A-5BC49622677A@panix.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
 <20140329173655.4022d715@bigbox.christie.dr>
 <F5F2BC07-AD55-46F1-970A-5BC49622677A@panix.com>
Message-ID: <20140329174653.4969807f@bigbox.christie.dr>

On 2014-03-29 18:41, Roy Smith wrote:
> On Mar 29, 2014, at 6:36 PM, Tim Chase wrote:
> 
> > And for cases where you have more than one or two things to test
> > for None-itude, you could use
> > 
> >  if all(x is None for x in [a, b, c, d]):
> >    do_something_if_theyre_all_None()
> 
> I might have written that as:
> 
> if set([a, b, c, d]) == set(None)
> 
> That's even clearer if you happen to already have the items in an
> iterable:
> 
> if set(conditions) == set(None)

Though am I correct that your iteration tests for equality, while
mine tests for identity?  Also, my version bails early in the event
quitting early is possible.  That's particularly useful in the case
of doing something like

  if all(x() is None for x in [func1, func2, func3, costly_func]):
    do_something()

-tkc





From roy at panix.com  Sat Mar 29 18:51:43 2014
From: roy at panix.com (Roy Smith)
Date: Sat, 29 Mar 2014 18:51:43 -0400
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <20140329173655.4022d715@bigbox.christie.dr>
 <F5F2BC07-AD55-46F1-970A-5BC49622677A@panix.com>
 <mailman.8703.1396133206.18130.python-list@python.org>
Message-ID: <roy-08D73A.18514329032014@news.panix.com>

In article <mailman.8703.1396133206.18130.python-list at python.org>,
 Tim Chase <tim at thechases.com> wrote:

> On 2014-03-29 18:41, Roy Smith wrote:
> > On Mar 29, 2014, at 6:36 PM, Tim Chase wrote:
> > 
> > > And for cases where you have more than one or two things to test
> > > for None-itude, you could use
> > > 
> > >  if all(x is None for x in [a, b, c, d]):
> > >    do_something_if_theyre_all_None()
> > 
> > I might have written that as:
> > 
> > if set([a, b, c, d]) == set(None)
> > 
> > That's even clearer if you happen to already have the items in an
> > iterable:
> > 
> > if set(conditions) == set(None)
> 
> Though am I correct that your iteration tests for equality, while
> mine tests for identity?

Hmmm, you're almost certainly correct on that, but you would have to 
have a perversely designed class for that to make a difference.  I'll 
take the increased readability.

> Also, my version bails early in the event
> quitting early is possible.  That's particularly useful in the case
> of doing something like
> 
>   if all(x() is None for x in [func1, func2, func3, costly_func]):
>     do_something()

Again, you're correct.  But, I'll take the increased readability over 
the premature optimization :-)


From tjreedy at udel.edu  Sat Mar 29 19:02:08 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Sat, 29 Mar 2014 19:02:08 -0400
Subject: checking if two things do not equal None
In-Reply-To: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
Message-ID: <lh7jdu$8rh$1@ger.gmane.org>

On 3/29/2014 2:56 PM, contact.trigon at gmail.com wrote:
> if (a, b) != (None, None):
> or
> if a != None != b:
>
> Preference? Pros? Cons? Alternatives?

if a is not None is not b
==
if a is not None and None is not b
==
if a is not None and b is not None
which is what I would write if not trying to be cute.
a < x < b is more readable as a chained comparison than the double is not.

-- 
Terry Jan Reedy



From rosuav at gmail.com  Sat Mar 29 19:17:49 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 30 Mar 2014 10:17:49 +1100
Subject: checking if two things do not equal None
In-Reply-To: <20140329174653.4969807f@bigbox.christie.dr>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
 <20140329173655.4022d715@bigbox.christie.dr>
 <F5F2BC07-AD55-46F1-970A-5BC49622677A@panix.com>
 <20140329174653.4969807f@bigbox.christie.dr>
Message-ID: <CAPTjJmrJLpd-0YvScTteW7ApySr4hbvmwQixRw1Ht1O5UahuDg@mail.gmail.com>

On Sun, Mar 30, 2014 at 9:46 AM, Tim Chase <tim at thechases.com> wrote:
> Though am I correct that your iteration tests for equality, while
> mine tests for identity?  Also, my version bails early in the event
> quitting early is possible.  That's particularly useful in the case
> of doing something like
>
>   if all(x() is None for x in [func1, func2, func3, costly_func]):
>     do_something()

Presumably you mean to actually call those functions, as checking the
identity of a costly function is still cheap :)

ChrisA


From contact.trigon at gmail.com  Sat Mar 29 19:20:09 2014
From: contact.trigon at gmail.com (contact.trigon at gmail.com)
Date: Sat, 29 Mar 2014 16:20:09 -0700 (PDT)
Subject: checking if two things do not equal None
In-Reply-To: <mailman.8699.1396130164.18130.python-list@python.org>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
 <mailman.8699.1396130164.18130.python-list@python.org>
Message-ID: <41055822-39c5-4783-ae95-018032cac952@googlegroups.com>

Thanks everyone; it has been very educational.

> Dave Angel:
> ...we'll find that two of the alternatives are not even equivalent.

That helped me realize (a,b) != (None, None) is not correct for the function.

It's a case where two parameters have None as the default argument. What I want is to make sure that both are not None. I am now considering:

if None not in (a,b):
or
if (a is not None) and (b is not None):


From ethan at stoneleaf.us  Sat Mar 29 19:20:40 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Sat, 29 Mar 2014 16:20:40 -0700
Subject: checking if two things do not equal None
In-Reply-To: <lh7cb4$ntu$2@news.albasani.net>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
Message-ID: <53375548.9040807@stoneleaf.us>

On 03/29/2014 02:01 PM, Johannes Bauer wrote:
> On 29.03.2014 20:05, Steven D'Aprano wrote:
>> On Sat, 29 Mar 2014 11:56:50 -0700, contact.trigon wrote:
>>
>>> if (a, b) != (None, None):
>>> or
>>> if a != None != b:
>>>
>>> Preference? Pros? Cons? Alternatives?
>>
>> if not (a is b is None): ...
>>
>> Or if you prefer:
>>
>> if a is not b is not None: ...
>
> Is this an obfuscated coding contest? Why do you opt for a solution that
> one has to at least think 2 seconds about when the simplest solution:
>
> if (a is not None) or (b is not None):
>
> is immediately understandable by everyone?

+1

--
~Ethan~


From python.list at tim.thechases.com  Sat Mar 29 21:19:06 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Sat, 29 Mar 2014 20:19:06 -0500
Subject: checking if two things do not equal None
In-Reply-To: <CAPTjJmrJLpd-0YvScTteW7ApySr4hbvmwQixRw1Ht1O5UahuDg@mail.gmail.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
 <20140329173655.4022d715@bigbox.christie.dr>
 <F5F2BC07-AD55-46F1-970A-5BC49622677A@panix.com>
 <20140329174653.4969807f@bigbox.christie.dr>
 <CAPTjJmrJLpd-0YvScTteW7ApySr4hbvmwQixRw1Ht1O5UahuDg@mail.gmail.com>
Message-ID: <20140329201906.4beab393@bigbox.christie.dr>

On 2014-03-30 10:17, Chris Angelico wrote:
> On Sun, Mar 30, 2014 at 9:46 AM, Tim Chase <tim at thechases.com>
> wrote:
>> Though am I correct that your iteration tests for equality, while
>> mine tests for identity?  Also, my version bails early in the
>> event quitting early is possible.  That's particularly useful in
>> the case of doing something like
>>
>>   if all(x() is None for x in [func1, func2, func3, costly_func]):
            ^^^
>>     do_something()
> 
> Presumably you mean to actually call those functions, as checking
> the identity of a costly function is still cheap :)

Which is what I do...calling only those necessary until the all/any
condition has been met. :-)

If you create the list of things to iterate over by calling them as
you create the list, then you don't save much of anything.  If you
only call until one of them breaks the any/all construct, you save
all the subsequent function calls.

-tkc






From rosuav at gmail.com  Sat Mar 29 21:37:28 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 30 Mar 2014 12:37:28 +1100
Subject: checking if two things do not equal None
In-Reply-To: <20140329201906.4beab393@bigbox.christie.dr>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
 <20140329173655.4022d715@bigbox.christie.dr>
 <F5F2BC07-AD55-46F1-970A-5BC49622677A@panix.com>
 <20140329174653.4969807f@bigbox.christie.dr>
 <CAPTjJmrJLpd-0YvScTteW7ApySr4hbvmwQixRw1Ht1O5UahuDg@mail.gmail.com>
 <20140329201906.4beab393@bigbox.christie.dr>
Message-ID: <CAPTjJmodZFPH+O9Wu5LsiodZKZ0uAiq8O88_1MDWi-5mPe08+Q@mail.gmail.com>

On Sun, Mar 30, 2014 at 12:19 PM, Tim Chase
<python.list at tim.thechases.com> wrote:
> On 2014-03-30 10:17, Chris Angelico wrote:
>> On Sun, Mar 30, 2014 at 9:46 AM, Tim Chase <tim at thechases.com>
>> wrote:
>>> Though am I correct that your iteration tests for equality, while
>>> mine tests for identity?  Also, my version bails early in the
>>> event quitting early is possible.  That's particularly useful in
>>> the case of doing something like
>>>
>>>   if all(x() is None for x in [func1, func2, func3, costly_func]):
>             ^^^
>>>     do_something()
>>
>> Presumably you mean to actually call those functions, as checking
>> the identity of a costly function is still cheap :)
>
> Which is what I do...calling only those necessary until the all/any
> condition has been met. :-)
>
> If you create the list of things to iterate over by calling them as
> you create the list, then you don't save much of anything.  If you
> only call until one of them breaks the any/all construct, you save
> all the subsequent function calls.

*facepalm* Yep, you do indeed. My bad! Take no notice of the man
behind the curtain...

ChrisA


From steve+comp.lang.python at pearwood.info  Sat Mar 29 22:04:14 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 30 Mar 2014 02:04:14 GMT
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
Message-ID: <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sat, 29 Mar 2014 17:07:20 -0400, Roy Smith wrote:

> I certainly agree that things like
> 
>> if a is not b is not None: ...
> 
> belong in an obfuscated coding contest. 

Apart from the fact that I got it wrong (that's what happens when I post 
at 6am after being up all night, thanks for the correction Lele), if you 
consider chained comparisons to be "obfuscated", I think you're not 
really fluent at Python. The OP even suggested  `a != None != b` so I 
think that (s)he at least understands chained comparisons.

However, I agree with Johannes that inverted conditions (using "not") are 
sometimes harder to reason about than "regular" conditions.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Sat Mar 29 22:15:18 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 30 Mar 2014 13:15:18 +1100
Subject: checking if two things do not equal None
In-Reply-To: <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmp7-EHGN_ujw8QVU1LhwPpw27q06ZNcZ1pa7dCzys06rg@mail.gmail.com>

On Sun, Mar 30, 2014 at 1:04 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Sat, 29 Mar 2014 17:07:20 -0400, Roy Smith wrote:
>
>> I certainly agree that things like
>>
>>> if a is not b is not None: ...
>>
>> belong in an obfuscated coding contest.
>
> Apart from the fact that I got it wrong (that's what happens when I post
> at 6am after being up all night, thanks for the correction Lele), if you
> consider chained comparisons to be "obfuscated", I think you're not
> really fluent at Python. The OP even suggested  `a != None != b` so I
> think that (s)he at least understands chained comparisons.
>
> However, I agree with Johannes that inverted conditions (using "not") are
> sometimes harder to reason about than "regular" conditions.

Chained comparisons where you're checking a single variable against
two constants make perfect sense:

2 < x < 5

Chained comparisons where you check a single constant against two
variables don't, so much:

x < 2 < y

What exactly does that mean, and why is it written that way? We can
figure out how the interpreter will parse that, but does that
correspond to the programmer's intention?

It'd be more useful but less clear if one of the conditions points the
other way:

x < 2 > y

which checks that they're both less than two, but IMO in a less-than-clear way.

ChrisA


From steve+comp.lang.python at pearwood.info  Sat Mar 29 22:24:59 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 30 Mar 2014 02:24:59 GMT
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <mailman.8701.1396132615.18130.python-list@python.org>
Message-ID: <5337807b$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sat, 29 Mar 2014 17:36:55 -0500, Tim Chase wrote:

> And for cases where you have more than one or two things to test for
> None-itude, you could use
> 
>   if all(x is None for x in [a, b, c, d]):
>     do_something_if_theyre_all_None()
> 
> or
> 
>   if all(x is not None for x in [a, b, c, d]):
>     do_something_if_no_Nones()
> 
> or
> 
>   if not any(x is None for x in [a, b, c, d]):
>     do_something_if_no_Nones()
> 
> which I find *much* more readable from a maintenance point of view.

With one or two things, I would stick to a regular comparison (skipping 
the "not"):

a is None
a is b is None

With three, I would consider either idiom:

a is b is c is None
all(x is None for x in (a, b, c))

but lean towards the use of all(). From four onwards I would definitely 
use all(), and of course if there is an arbitrary number of items, I 
would definitely use all().



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From roy at panix.com  Sat Mar 29 22:39:45 2014
From: roy at panix.com (Roy Smith)
Date: Sat, 29 Mar 2014 22:39:45 -0400
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
Message-ID: <roy-346471.22394529032014@news.panix.com>

In article <mailman.8709.1396145720.18130.python-list at python.org>,
 Chris Angelico <rosuav at gmail.com> wrote:

> Chained comparisons where you're checking a single variable against
> two constants make perfect sense:
> 
> 2 < x < 5
> 
> Chained comparisons where you check a single constant against two
> variables don't, so much:
> 
> x < 2 < y

To me, chained comparisons make intuitive sense when they're all "<" (or 
"<=").  I just think back to junior high school algebra class, with the 
big number line above the blackboard.  Thus,

 a < b < c

means if you put a, b, and c on the number line, a is to the left of b, 
which is to the left of c.  I have no problem extending that to more 
than three values:

 a < b < c < d < e

still makes intuitive sense.  I have no particular problem with

 x < 2 < y

because it fits the same pattern.  But, if you show me

 a != None != b:

my brain just goes into overload.  Honestly, I don't even know what that 
means.  My brain keeps trying to stick a, None, and b on Mrs. Albaum's 
number line and keeps walking into the wall.  If you (the editorial you) 
tell me that my failure to grok that expression means I'm not fluent in 
Python, well then, guilty as charged.


From roy at panix.com  Sat Mar 29 22:43:00 2014
From: roy at panix.com (Roy Smith)
Date: Sat, 29 Mar 2014 22:43:00 -0400
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <mailman.8701.1396132615.18130.python-list@python.org>
 <5337807b$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-D862BF.22430029032014@news.panix.com>

In article <5337807b$0$29994$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> a is b is c is None

And we are all together.  See how they run like pigs from a gun, see how 
they fly.


From michael.weylandt at gmail.com  Sat Mar 29 22:50:31 2014
From: michael.weylandt at gmail.com (R. Michael Weylandt)
Date: Sat, 29 Mar 2014 22:50:31 -0400
Subject: Dynamically reference member of array
In-Reply-To: <d9daaeb5-04ef-43e8-b60e-3c4ba5790a9d@googlegroups.com>
References: <d9daaeb5-04ef-43e8-b60e-3c4ba5790a9d@googlegroups.com>
Message-ID: <CAAmySGMxCp63NbGrt1XBtEjG7j5Am4KzKQx-XsUsa0_gmjeoYw@mail.gmail.com>

On Wed, Mar 26, 2014 at 7:43 AM, Ben Collier <bmcollier at gmail.com> wrote:
> Hi all,
>
> I know that I can dynamically reference a variable with locals()["i"], for instance, but I'd like to know how to do this with a variable in an object.
>
> If I have an object called "device", with variables called attr1, attr2 .. attr50, how could I dynamically reference these?
>

I think the pythonic term you're looking for is "attribute". See
getattr() and setattr()

Cheers,
Michael


From rustompmody at gmail.com  Sat Mar 29 22:54:09 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Sat, 29 Mar 2014 19:54:09 -0700 (PDT)
Subject: checking if two things do not equal None
In-Reply-To: <roy-346471.22394529032014@news.panix.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
 <roy-346471.22394529032014@news.panix.com>
Message-ID: <308493ad-d904-4897-8d7d-6f7780a6bb7d@googlegroups.com>

On Sunday, March 30, 2014 8:09:45 AM UTC+5:30, Roy Smith wrote:
> I have no particular problem with

>  x < 2 < y

> because it fits the same pattern.  But, if you show me

>  a != None != b:

> my brain just goes into overload.  Honestly, I don't even know what that 
> means.  My brain keeps trying to stick a, None, and b on Mrs. Albaum's 
> number line and keeps walking into the wall.  If you (the editorial you) 
> tell me that my failure to grok that expression means I'm not fluent in 
> Python, well then, guilty as charged.

<Math Terminology>
A relation that is reflexive antisymmetric and transitive is a partial order
Strict order: Irreflexive asymmetric and transitive
Both are strongly related
For general R (partial) S (strict)

S from R
xSy = xRy ? x ? y
R from S
xRy = xSy ? x=y
</Math Terminology>

For both these chained comparisons are natural

!= is not transitive: 2 != 3 and 3  != 2 ? 2 == 2

So for != chained comparisons are not natural (or IMHO appropriate)


From zachary.ware+pylist at gmail.com  Sat Mar 29 23:04:39 2014
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Sat, 29 Mar 2014 22:04:39 -0500
Subject: checking if two things do not equal None
In-Reply-To: <roy-D862BF.22430029032014@news.panix.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <mailman.8701.1396132615.18130.python-list@python.org>
 <5337807b$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-D862BF.22430029032014@news.panix.com>
Message-ID: <2f7e07e3-4db6-467d-b662-a3db18f69889@email.android.com>



On March 29, 2014 9:43:00 PM CDT, Roy Smith <roy at panix.com> wrote:
>In article <5337807b$0$29994$c3e8da3$5496439d at news.astraweb.com>,
> Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>
>> a is b is c is None
>
>And we are all together.  See how they run like pigs from a gun, see
>how 
>they fly.

I'm cryin'.

(Really, that was terrible.)

Walrus-ly y'rs,

Zach



From harrismh777 at gmail.com  Sun Mar 30 01:52:20 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sun, 30 Mar 2014 00:52:20 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
Message-ID: <lh8bej$n7b$1@speranza.aioe.org>

On 3/29/14 10:45 AM, Mark Lawrence wrote:
> On 29/03/2014 08:21, Mark H Harris wrote:
>>
>>     Yes. Well, as the joke goes, if you're trilingual you speak three
>> languages, if you're bilingual you speak two languages, if you're
>> monolingual you're an American (well, that might go for Australia too,
>> maybe). When whole continents speak the same language that tends to
>> happen.
>
> You mean like the USA, where I saw an ad in a shop for a bilingual shop
> assistant?  Or is Spanish so like US English it doesn't count as a
> separate language?

I'm not sure what point you are trying to make. We have people here from 
all over the earth, and enough illegal immigrants speaking Spanish to 
account for a population about the size of Ohio. But, Americans are 
mostly monolingual. ...point of fact.

The people of the United States are in a smallish battle over whether 
the official language of the United States should be English? In other 
words, no special signs, if you're going to live here you're going to 
learn English (end of the story, for some people).

I'm not in that camp. I am preparing to start French studies soon. My 
son and daughter are fifth year fluent in Spanish (my daughter is 
minoring in Spanish, and plans study abroad for that purpose as she 
prepares for medical school.

There is no nice way to say this... we have a lot of pin-headed bigots 
living here that have to intention nor inclination to learn another 
language. Some of them even think that if English was good enough for 
Jesus , its got to be good enough for them (I'm not kidding).

Sadly, true.

But then, more than half of our population is not aware that the earth 
revolves around the sun, either.    :-}

Cheers


From steve+comp.lang.python at pearwood.info  Sun Mar 30 01:54:11 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 30 Mar 2014 05:54:11 GMT
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
Message-ID: <5337b182$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sun, 30 Mar 2014 13:15:18 +1100, Chris Angelico wrote:

> On Sun, Mar 30, 2014 at 1:04 PM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> On Sat, 29 Mar 2014 17:07:20 -0400, Roy Smith wrote:
>>
>>> I certainly agree that things like
>>>
>>>> if a is not b is not None: ...
>>>
>>> belong in an obfuscated coding contest.
>>
>> Apart from the fact that I got it wrong (that's what happens when I
>> post at 6am after being up all night, thanks for the correction Lele),
>> if you consider chained comparisons to be "obfuscated", I think you're
>> not really fluent at Python. The OP even suggested  `a != None != b` so
>> I think that (s)he at least understands chained comparisons.
>>
>> However, I agree with Johannes that inverted conditions (using "not")
>> are sometimes harder to reason about than "regular" conditions.
> 
> Chained comparisons where you're checking a single variable against two
> constants make perfect sense:
> 
> 2 < x < 5
> 
> Chained comparisons where you check a single constant against two
> variables don't, so much:
> 
> x < 2 < y
> 
> What exactly does that mean, and why is it written that way? 

It checks that 2 is strictly bounded between x on the left and y on the 
right, i.e. that 2 is inside the open interval x...y. I don't know why 
you think that's unclear. But then I do have a maths background and I'm 
used to chaining comparisons.

Write it like this:

low = x
high = y
a = 2

low < a < high

Does that make more sense? Well-chosen names are good. The fact that a is 
a constant rather than a variable is no big deal:

low < 2 < high


> We can
> figure out how the interpreter will parse that, but does that correspond
> to the programmer's intention?

That applies to just about anything:

(x % 2 == 1) or (x > 0)

What that my intention, or did I intend to write

(x % 2 == 0) and (x < 0)


At some point you just have to accept that, in the absence of clearly 
nonsensical code or a contradiction between the documentation and the 
behaviour (i.e. a bug), the programmer will have written what she 
intended to write.


> It'd be more useful but less clear if one of the conditions points the
> other way:
> 
> x < 2 > y
> 
> which checks that they're both less than two, 

which is quite different from what you wrote the first time.


> but IMO in a less-than-clear way.

That's an understatement. If I saw code chaining comparisons in that 
fashion, I would assume the second operator > was a typo.

Chaining less-than and greater than operators should, for clarity, always 
be written in a single order. E.g. a <= b < c < d, not a <= b < d > c.

(The second contains a subtle bug too.)



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From harrismh777 at gmail.com  Sun Mar 30 01:57:41 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sun, 30 Mar 2014 00:57:41 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<mailman.8369.1395437459.18130.python-list@python.org>	<a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>	<mailman.8377.1395456097.18130.python-list@python.org>	<dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>	<lgj4sp$7ed$1@speranza.aioe.org>	<532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>	<53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>	<87txahi68z.fsf@elektro.pacujo.net>	<roy-94490C.07534229032014@news.panix.com>
 <87lhvti5as.fsf@elektro.pacujo.net>
Message-ID: <lh8bol$npe$1@speranza.aioe.org>

On 3/29/14 6:59 AM, Marko Rauhamaa wrote:
> I hate localization. You get a error message in Finnish from "make" or
> "grep" and then you try to google it.
>
> So mine is en_US, but I know people who do fi_FI.

... this is my point precisely.




From steve+comp.lang.python at pearwood.info  Sun Mar 30 02:08:37 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 30 Mar 2014 06:08:37 GMT
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
 <roy-346471.22394529032014@news.panix.com>
 <308493ad-d904-4897-8d7d-6f7780a6bb7d@googlegroups.com>
Message-ID: <5337b4e4$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sat, 29 Mar 2014 19:54:09 -0700, Rustom Mody wrote:

> On Sunday, March 30, 2014 8:09:45 AM UTC+5:30, Roy Smith wrote:
>> I have no particular problem with
> 
>>  x < 2 < y
> 
>> because it fits the same pattern.  But, if you show me
> 
>>  a != None != b:
> 
>> my brain just goes into overload.  Honestly, I don't even know what
>> that means.  My brain keeps trying to stick a, None, and b on Mrs.
>> Albaum's number line and keeps walking into the wall.  If you (the
>> editorial you) tell me that my failure to grok that expression means
>> I'm not fluent in Python, well then, guilty as charged.
> 
> <Math Terminology>
[...]
> So for != chained comparisons are not natural (or IMHO appropriate)

I tend to agree they're "not natural", although appropriate is another 
thing. The problem is that we tend to read something like:

    a != b != c

as "all of a, b and c are unequal", corresponding to:

    a == b == c

as "all of a, b and c are equal". But that's not what it means. It means 
that a != b and b != c, but it says nothing about a and c. And that was 
my mistake. The OP actually got it right in their first post, but 
sticking None in the middle to ensure it partakes of both comparisons.

    a is not None is not b

Still, that's not easily extended to a third item, this would be wrong:

    a is not None is not b is not c

since c only gets compared against b, not None. Better is to factor the 
"not" out:

    not (a is b is c is None)


which now should be clear: you're testing whether or not *all* of a, b 
and c are None. If you prefer:

    not all(x is None for x in (a, b, c))


Which is more readable is a matter of personal preference.

I think Johannes got it right: boolean logic is easier to reason about 
when there is a minimum of "not"s.


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Sun Mar 30 02:17:34 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 30 Mar 2014 17:17:34 +1100
Subject: checking if two things do not equal None
In-Reply-To: <5337b182$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
 <5337b182$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqRP=xcDd18pvBb5brSm8k4h_Vu_7-=u6YCCMCYN3vXUw@mail.gmail.com>

On Sun, Mar 30, 2014 at 4:54 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> On Sun, 30 Mar 2014 13:15:18 +1100, Chris Angelico wrote:
>
>> Chained comparisons where you're checking a single variable against two
>> constants make perfect sense:
>>
>> 2 < x < 5
>>
>> Chained comparisons where you check a single constant against two
>> variables don't, so much:
>>
>> x < 2 < y
>>
>> What exactly does that mean, and why is it written that way?
>
> It checks that 2 is strictly bounded between x on the left and y on the
> right, i.e. that 2 is inside the open interval x...y. I don't know why
> you think that's unclear. But then I do have a maths background and I'm
> used to chaining comparisons.
>
> Write it like this:
>
> low = x
> high = y
> a = 2
>
> low < a < high
>
> Does that make more sense? Well-chosen names are good. The fact that a is
> a constant rather than a variable is no big deal:
>
> low < 2 < high

The problem isn't that I can't see what the comparisons are. It makes
very good sense to bound a variable within constants; but you already
know exactly where 2 is on the number line, so asking "Is 2 between
these two variables" seems a bit odd. Maybe it's less so with the
strong mathematical background, but it seems odd to me.

>> It'd be more useful but less clear if one of the conditions points the
>> other way:
>>
>> x < 2 > y
>>
>> which checks that they're both less than two,
>
> which is quite different from what you wrote the first time.
>
>
>> but IMO in a less-than-clear way.
>
> That's an understatement. If I saw code chaining comparisons in that
> fashion, I would assume the second operator > was a typo.
>
> Chaining less-than and greater than operators should, for clarity, always
> be written in a single order. E.g. a <= b < c < d, not a <= b < d > c.
>
> (The second contains a subtle bug too.)

Agreed.

ChrisA


From greg.ewing at canterbury.ac.nz  Sun Mar 30 02:16:47 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Sun, 30 Mar 2014 19:16:47 +1300
Subject: unicode as valid naming symbols
In-Reply-To: <mailman.8700.1396130521.18130.python-list@python.org>
References: <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com> <53320793.8070501@stoneleaf.us>
 <533241C0.8020109@mrabarnett.plus.com> <53329549.1000208@rece.vub.ac.be>
 <CALwzidm9Gajc4pgR36aQrdiV7zCbN91nV0xrBixpNKysh=OnjQ@mail.gmail.com>
 <mailman.8607.1395912965.18130.python-list@python.org>
 <bbe6f1ef-f6e6-4e3d-9dc3-8b3b66edaf40@googlegroups.com>
 <mailman.8673.1396032954.18130.python-list@python.org>
 <a8faddd0-c494-41b9-8334-a2ec780fca61@googlegroups.com>
 <6d2ej9hve7v7m3jfbre1jn9v1loacfr8lo@4ax.com>
 <mailman.8700.1396130521.18130.python-list@python.org>
Message-ID: <bppr6bFii9mU1@mid.individual.net>

Chris Angelico wrote:
> a 5x8 bitmap has
> forty pixels, any of which can be either on or off - that gives
> roughly twice as much data space as the 21-bit Unicode spec.

We don't need a font, then -- just map the pixels
straight onto bits in the character code!

Might require some user re-education, but that's
a small price to pay for saving so much memory
space.

-- 
Greg


From harrismh777 at gmail.com  Sun Mar 30 02:22:55 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sun, 30 Mar 2014 01:22:55 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<mailman.8369.1395437459.18130.python-list@python.org>	<a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>	<mailman.8377.1395456097.18130.python-list@python.org>	<dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>	<lgj4sp$7ed$1@speranza.aioe.org>	<532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>	<53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh5iqs$j0m$1@speranza.aioe.org>
 <53370898$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh8d7u$qcr$1@speranza.aioe.org>

On 3/29/14 12:53 PM, Steven D'Aprano wrote:
> People have had localised code pages, and localised keyboards to enter
> characters in those code pages, for up to 30 years, if not longer.

    Nobody is arguing otherwise, Steven. Having a code page for a local 
language is not the same thing as having software that supports your 
local language code page! Software and code pages improved over time, 
but international communication (which is what I'm talking about) has 
always been done in English, using ASCII. Well except when Guido brought 
the ABC stuff to the states back in the day and had no way to do that 
except to fly himself (and the tape) personally.
>
> In some of those cases, the localisation was done by companies like IBM,
> Microsoft and Apple, realising that if they wanted to sell computers
> outside of the US, they needed to supply computers that were localised to
> their market.

    Unfortunately that happened way late. And even then, international 
communication was still done (and is still done) in English. Only until 
very recently (see my post to Chris) has unicode improved to the point 
where international comm can occur reliably enough (input, font, code 
points) to allow comm in languages other than English. And yet, although 
Kanji has been around for a while, most international comm is still 
handled in English because its the lingua franca.


> This code page system actually worked pretty well, so long as you only
> exchange documents with people using the same code page. Until the
> Internet, that was mostly the case.

    My point exactly. With the advent of the Internet, almost *all* comm 
is English with minor notable exceptions in today's environment. Just 
look around, you need not argue with me. You can find places for local 
comm, but they are sparse.

>
>> That's why they called it ASCII American Standard
>> Code for Information Interchange...
>
> Yes. So what? Just because ASCII exists doesn't mean everyone uses it
> *exclusively*.

    Yeah, well, that's exactly what happened; its still happening. Only 
today its UTF-8, a Latin script (there is only one) and thousands of 
people all over the earth on the Internet speaking English around the 
globe.  Yeah, I know, there are localized pockets and people using their 
computer in their heart language, but for international communication 
you're going to find (primarily) people communicating in English.

> With the demise of EBCDIC as the standard character encoding (actually
> plural encodings, because EBCDIC has code pages too),

    Ha!  That's funny.   EBCIDIC is | was  standard only at IBM. Those 
stubborn people (I used to be one of them) stuck with EBCIDIC and 
SNA/SDLC until they realized that they could not communicate with the 
rest of the world using ASCII and TCP/IP.  ... just hilarious!

> ASCII has become
> the lowest common denominator for most (but not all) character sets. Pre-
> Unicode, most (but definitely not all!) code pages were based on ASCII,
> either with a few changes, or extending it to a full 8 bits.

    Yup.

> But that's the point:

    Yes it is.

> most people with access to computing in the first
> place, also had access to input methods and code pages for their native
> language. Your idea that they were forced to use ASCII exclusively, with
> no way of entering their own language, is simply wrong.

    I'm not arguing that, Steven. You're just being silly. I'm talking 
about be forced to communicate around the world when most of the people 
communicating are speaking English and using ASCII.
    Look, I can unplug my computer from the Internet and use it to 
translate biblical Greek and O.T. Hebrew and be happy as a clam that I'm 
locally doing my own thing in my own language (so what)? The moment I 
want to communicate outside my local space I better know English, and I 
better have a code page that supports it.
    If you live in Israel, and only communicate with people in Israel, 
you can use your modern Hebrew font and code page and be happy as a 
clam; but if you want to communicate with somebody in IOWA, perhaps Iowa 
State for some reason, you better know English. Just say'n.
    On the other hand, just look around  the Internet. 98% of all 
communication is English using UTF-8 today. Yes, you can find pockets 
where this is not true, but primarily, the world is using a modern 
lingua franca.

    I am very interested with the intense interest in this topic.


marcus



From steve+comp.lang.python at pearwood.info  Sun Mar 30 02:31:36 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 30 Mar 2014 06:31:36 GMT
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
Message-ID: <5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sun, 30 Mar 2014 00:52:20 -0500, Mark H Harris wrote:

> On 3/29/14 10:45 AM, Mark Lawrence wrote:
>> On 29/03/2014 08:21, Mark H Harris wrote:
>>>
>>>     Yes. Well, as the joke goes, if you're trilingual you speak three
>>> languages, if you're bilingual you speak two languages, if you're
>>> monolingual you're an American (well, that might go for Australia too,
>>> maybe). When whole continents speak the same language that tends to
>>> happen.
>>
>> You mean like the USA, where I saw an ad in a shop for a bilingual shop
>> assistant?  Or is Spanish so like US English it doesn't count as a
>> separate language?
> 
> I'm not sure what point you are trying to make. We have people here from
> all over the earth, and enough illegal immigrants speaking Spanish to
> account for a population about the size of Ohio.

*raises eyebrow*

Did you intend to imply that it is only illegal immigrants who speak 
Spanish in the USA?

The most recent US census found there are 38.5 million people in the US 
who primarily speak Spanish, and 45 million who speak it as their first 
or second language. In comparison, there are only an estimated 11 million 
illegal immigrants (of which only 7 million is from Mexico).

https://en.wikipedia.org/wiki/Spanish_language_in_the_United_States



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Sun Mar 30 02:43:31 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 30 Mar 2014 17:43:31 +1100
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
In-Reply-To: <5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
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 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmoD6OLVQ_vgmW1mRXHVThBmT+U+PJKszX7t=mMibiGZ1w@mail.gmail.com>

On Sun, Mar 30, 2014 at 5:31 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Did you intend to imply that it is only illegal immigrants who speak
> Spanish in the USA?

I think he's correct there. After all, anyone who doesn't fit the
white-skinned monolingual (barely-one-language, really) middle-class
stereotype *MUST* be an illegal immigrant - right? That's how you
recognize who to be rude to.

http://notalwaysright.com/pepperoni-extremism/3163
http://notalwaysright.com/no-obamacare-for-you/17102
http://notalwaysworking.com/they-are-rotten-to-the-corps-part-2/32108
... and plenty more stories besides.

ChrisA


From greg.ewing at canterbury.ac.nz  Sun Mar 30 02:41:36 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Sun, 30 Mar 2014 19:41:36 +1300
Subject: checking if two things do not equal None
In-Reply-To: <roy-346471.22394529032014@news.panix.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
 <roy-346471.22394529032014@news.panix.com>
Message-ID: <bppsksFir59U1@mid.individual.net>

Roy Smith wrote:
> But, if you show me
> 
>  a != None != b:
> 
> my brain just goes into overload.

Chained comparisons get weird with not-equal operators.
If you see

   a == b == c

then it implies that a == c, but

   a != b != c

does *not* imply that a != c. At least it doesn't in
Python; I've never seen any mathematicians write that, so
I don't know what they would make of it.

-- 
Greg


From harrismh777 at gmail.com  Sun Mar 30 02:48:27 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sun, 30 Mar 2014 01:48:27 -0500
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<lgj4sp$7ed$1@speranza.aioe.org>	<532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>	<53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh5iqs$j0m$1@speranza.aioe.org>	<mailman.8683.1396069736.18130.python-list@python.org>	<53365F55.2040302@gmail.com>	<mailman.8688.1396073027.18130.python-list@python.org>	<lh5vq3$c1j$1@speranza.aioe.org>	<mailman.8690.1396107966.18130.python-list@python.org>	<lh8bej$n7b$1@speranza.aioe.org>
 <5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lh8enq$t7e$1@speranza.aioe.org>

On 3/30/14 1:31 AM, Steven D'Aprano wrote:
>> I'm not sure what point you are trying to make. We have people here from
>> all over the earth, and enough illegal immigrants speaking Spanish to
>> account for a population about the size of Ohio.
>
> *raises eyebrow*
>
> Did you intend to imply that it is only illegal immigrants who speak
> Spanish in the USA?

    Don't be silly, Steven, it doesn't become you.

> The most recent US census found there are 38.5 million people in the US
> who primarily speak Spanish, and 45 million who speak it as their first
> or second language. In comparison, there are only an estimated 11 million
> illegal immigrants (of which only 7 million is from Mexico).
>
> https://en.wikipedia.org/wiki/Spanish_language_in_the_United_States

    Hilarious!   That's part of the problem, um, its because they are 
*illegal* that the census bureau does not know about them in terms of 
exact numbers; its a nice effort though.

    America is a melting pot (always has been). We have thousands of 
ethnic groups living here and thousands of languages spoken here. All of 
them are in some place on the continuum of English as a second language; 
its the only way to survive here.


marcus




From ben+python at benfinney.id.au  Sun Mar 30 02:52:07 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sun, 30 Mar 2014 17:52:07 +1100
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
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 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
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 <CAPTjJmqRP=xcDd18pvBb5brSm8k4h_Vu_7-=u6YCCMCYN3vXUw@mail.gmail.com>
Message-ID: <85wqfcmb54.fsf@benfinney.id.au>

Chris Angelico <rosuav at gmail.com> writes:

> The problem isn't that I can't see what the comparisons are. It makes
> very good sense to bound a variable within constants; but you already
> know exactly where 2 is on the number line, so asking "Is 2 between
> these two variables" seems a bit odd. Maybe it's less so with the
> strong mathematical background, but it seems odd to me.

I don't feel odd about asking the question ?Is 2 between these two
values??. It's straightforward and concise. Can you explain better why
you find it odd?

-- 
 \     ?You are welcome to visit the cemetery where famous Russian and |
  `\    Soviet composers, artists, and writers are buried daily except |
_o__)                   Thursday.? ?Russian orthodox monastery, Moscow |
Ben Finney



From orgnut at yahoo.com  Sun Mar 30 02:53:46 2014
From: orgnut at yahoo.com (Larry Hudson)
Date: Sat, 29 Mar 2014 23:53:46 -0700
Subject: Keyboard standards
In-Reply-To: <mailman.8697.1396122111.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
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Message-ID: <jbWdnfUg1bDmIqrOnZ2dnUVZ_rqdnZ2d@giganews.com>

On 03/29/2014 12:41 PM, Michael Torrie wrote:
> On 03/29/2014 01:27 PM, Larry Hudson wrote:
>> On 03/28/2014 09:26 PM, Mark H Harris wrote:
>>>
>>> PS   Thunderbird puts *both* the list and the news group addys in the to: header field on
>>> reply-to-list.   ~nice, huh.
>>
>> Must be the way YOU set it up.  MY Thunderbird (currently version 24.4.0 on Mint Linux 16)
>> doesn't do any such thing.  Besides, "Reply" sends private e-mail to the poster -- "Followup"
>> sends to the newsgroup.
>
> No, Mark describes the standard way Thunderbird works.  Reply-to-List
> does what he says it does. Not sure why your installation works
> differently.  I guess maybe you are talking about something different.
> The mailing list vs the NNTP list.
>
You're right -- I use the NNTP list only.  I've never looked at the Python mailing list.  The 
very few mailing lists I subscribe to, I only read--never reply to.  Come to think of it, 
currently there's only one, and I rarely do more than skim it briefly--and frequently not even 
that.  I should drop it altogether, just haven't bothered to do so.

      -=- Larry -=-



From orgnut at yahoo.com  Sun Mar 30 03:32:58 2014
From: orgnut at yahoo.com (Larry Hudson)
Date: Sun, 30 Mar 2014 00:32:58 -0700
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <lh8bej$n7b$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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Message-ID: <j8-dne29t9g2VarOnZ2dnUVZ_qSdnZ2d@giganews.com>

On 03/29/2014 10:52 PM, Mark H Harris wrote:
> On 3/29/14 10:45 AM, Mark Lawrence wrote:
>> On 29/03/2014 08:21, Mark H Harris wrote:
>>>
>>>     Yes. Well, as the joke goes, if you're trilingual you speak three
>>> languages, if you're bilingual you speak two languages, if you're
>>> monolingual you're an American (well, that might go for Australia too,
>>> maybe). When whole continents speak the same language that tends to
>>> happen.
>>
>> You mean like the USA, where I saw an ad in a shop for a bilingual shop
>> assistant?  Or is Spanish so like US English it doesn't count as a
>> separate language?
>
> I'm not sure what point you are trying to make. We have people here from all over the earth, and
> enough illegal immigrants speaking Spanish to account for a population about the size of Ohio.
> But, Americans are mostly monolingual. ...point of fact.
>

I believe the point is your generalized use of "American".  After all, Mexicans are Americans 
too, as well as Canadians, Peruvians and ...

Unfortunately, there is no good word for "USA-ian".  "United States Citizen" is too long and 
awkward and "United Statesian" is ridiculous.  The common usage of "American" for this is at 
best ambiguous, and definitely inaccurate (as well as chauvinistic, and rather insulting to 
other North and South Americans outside the US).

      -=- Larry -=-



From rosuav at gmail.com  Sun Mar 30 03:36:49 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 30 Mar 2014 18:36:49 +1100
Subject: checking if two things do not equal None
In-Reply-To: <85wqfcmb54.fsf@benfinney.id.au>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
 <5337b182$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmqRP=xcDd18pvBb5brSm8k4h_Vu_7-=u6YCCMCYN3vXUw@mail.gmail.com>
 <85wqfcmb54.fsf@benfinney.id.au>
Message-ID: <CAPTjJmphdS7mC1b3HWhHOZKTA5nC0oxX6-8KBa=VgR5HDO5njw@mail.gmail.com>

On Sun, Mar 30, 2014 at 5:52 PM, Ben Finney <ben+python at benfinney.id.au> wrote:
> Chris Angelico <rosuav at gmail.com> writes:
>
>> The problem isn't that I can't see what the comparisons are. It makes
>> very good sense to bound a variable within constants; but you already
>> know exactly where 2 is on the number line, so asking "Is 2 between
>> these two variables" seems a bit odd. Maybe it's less so with the
>> strong mathematical background, but it seems odd to me.
>
> I don't feel odd about asking the question ?Is 2 between these two
> values??. It's straightforward and concise. Can you explain better why
> you find it odd?

Possibly because the "variable between two constants" is something
I've done often (usually in the more explicit form of "x > min && x <
max" in a language without chained comparisons), usually
bounds-checking some value. I've never had to ask whether a single
constant has two variables, one on either side. But that's just that
I've personally never done it; it doesn't mean nobody does it, by any
means.

ChrisA


From marko at pacujo.net  Sun Mar 30 03:37:45 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 30 Mar 2014 10:37:45 +0300
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net>
 <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
 <roy-346471.22394529032014@news.panix.com>
 <bppsksFir59U1@mid.individual.net>
Message-ID: <87y4zsf86u.fsf@elektro.pacujo.net>

Gregory Ewing <greg.ewing at canterbury.ac.nz>:

>   a != b != c
>
> does *not* imply that a != c. At least it doesn't in Python; I've
> never seen any mathematicians write that, so I don't know what they
> would make of it.

Any resemblance between mathematics notation and Python is purely
coincidental. I must admit I had missed Python's chained comparisons
until this discussion, but now I looked up the definition:

    comparison    ::=  or_expr ( comp_operator or_expr )*
    comp_operator ::=  "<" | ">" | "==" | ">=" | "<=" | "!="
                       | "is" ["not"] | ["not"] "in"

    [...]

    Formally, if a, b, c, ..., y, z are expressions and op1, op2, ...,
    opN are comparison operators, then a op1 b op2 c ... y opN z is
    equivalent to a op1 b and b op2 c and ... y opN z, except that each
    expression is evaluated at most once.


That means, in my opinion, that you should feel free to use chaining any
way you see fit. Also, the rule is crystal-clear and easy to grasp:
there's an implicit "and" there.

It's another thing, then, if it was a good idea to include chaining
there in the first place, but I trust the idea was properly vetted and
double checked against possible parsing ambiguities.

Even without chaining "is not" is a bit suspect:

    >>> False is not 0
    True
    >>> False is (not 0)
    False
    >>> False is not not not 0
      File "<stdin>", line 1
        False is not not not 0
                       ^
    SyntaxError: invalid syntax



Marko


From steve+comp.lang.python at pearwood.info  Sun Mar 30 06:35:48 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 30 Mar 2014 10:35:48 GMT
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this
 Python language feature?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
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 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
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 <53365F55.2040302@gmail.com>
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Message-ID: <5337f383$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sun, 30 Mar 2014 01:48:27 -0500, Mark H Harris wrote:

> On 3/30/14 1:31 AM, Steven D'Aprano wrote:
>>> I'm not sure what point you are trying to make. We have people here
>>> from all over the earth, and enough illegal immigrants speaking
>>> Spanish to account for a population about the size of Ohio.
>>
>> *raises eyebrow*
>>
>> Did you intend to imply that it is only illegal immigrants who speak
>> Spanish in the USA?
> 
>     Don't be silly, Steven, it doesn't become you.

Given the sorts of patronising, condescending things you insist are true 
about non-Americans, such as their supposed inability to communicate in 
their own language on the Internet, I wasn't sure.

>> The most recent US census found there are 38.5 million people in the US
>> who primarily speak Spanish, and 45 million who speak it as their first
>> or second language. In comparison, there are only an estimated 11
>> million illegal immigrants (of which only 7 million is from Mexico).
>>
>> https://en.wikipedia.org/wiki/Spanish_language_in_the_United_States
> 
>     Hilarious!   That's part of the problem, um, its because they are
> *illegal* that the census bureau does not know about them in terms of
> exact numbers; its a nice effort though.

The number of illegal immigrants is not estimated from the Census numbers 
directly. It's not like they have a tick box "Are you in this country 
illegally?".

Just because *you* don't know how illegal immigrant numbers are 
estimated, or what margin of error those estimates might have, don't make 
the mistake of imagining that any such effort is "hilarious", a joke, or 
otherwise useless. Naturally the figure is *estimated*, I even said it 
was estimated, and gave it as a round number.

If I had said there were 11,205,971 illegal immigrants in the USA as of 
last Tuesday, then you would have a good excuse to mock my spurious 
precision. Otherwise, not so much.


>     America is a melting pot (always has been). We have thousands of
> ethnic groups living here and thousands of languages spoken here.

Not really. There are under 350 languages spoken in the USA. Over 92% of 
the population speaking just two of them, English and Spanish, with 
Chinese a *very* distant third. Only eight languages are spoken by more 
than 1 million people. Even if you double that figure, to capture "that 
one guy who speaks Gunwinyguan" and other outliers, you still end up well 
under even a single thousand.

The surprising thing to me about this is not that the number of languages 
is so low (there are about 6000-7000 languages in the world), but that it 
is so high. I would have predicted well under 100. After all, spoken 
language popularity is an excellent example of network effects: the more 
people who speak a language, the more valuable it is to speak the same 
language.

Network effects explain why, out of the six or seven thousand languages 
in the world, just thirteen account for more than half the world's 
population:

1) Mandarin
2) Spanish
3) English
4) Hindi
5) Arabic
6) Portuguese
7) Bengali
8) Russian
9) Japanese
10) Punjabi
11) German
12) Javanese
13) Wu

adding up to 51%. The next thirteen bring the total to 64%.

(Figures are, naturally, approximate and subject to change.)


> All of
> them are in some place on the continuum of English as a second language;
> its the only way to survive here.

Approximately 5% of the US population either do not speak English at all, 
or speak it poorly. That includes approximately half a million ASL 
speakers (American Sign Language, which is not a manual representation of 
English but an independent language in it's own right), the majority of 
whom are unable to speak or understand spoken English.

Be careful of making sweeping generalisations like "the only way to 
survive". Especially when they're so judgemental. It's not like there are 
gangs of armed militia hunting down deaf children and foreign grannies 
who only speak the language of their homeland. Well, maybe in Arizona.

*wink*



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Sun Mar 30 06:44:13 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 30 Mar 2014 10:44:13 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
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 <mailman.8690.1396107966.18130.python-list@python.org>
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Message-ID: <5337f57d$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sun, 30 Mar 2014 00:32:58 -0700, Larry Hudson wrote:

> Unfortunately, there is no good word for "USA-ian".  "United States
> Citizen" is too long and awkward and "United Statesian" is ridiculous. 
> The common usage of "American" for this is at best ambiguous, and
> definitely inaccurate (as well as chauvinistic, and rather insulting to
> other North and South Americans outside the US).

Among fans of the British writer Terry Pratchett, the usual term is 
Merkins. Including among Merkin fans.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From rosuav at gmail.com  Sun Mar 30 08:03:26 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 30 Mar 2014 23:03:26 +1100
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
In-Reply-To: <5337f383$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
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Message-ID: <CAPTjJmq6rQdS-SRUyQBNJ0T4MqkZO-pBRqzTQnFNep5MxDdDrg@mail.gmail.com>

On Sun, Mar 30, 2014 at 9:35 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
> Network effects explain why, out of the six or seven thousand languages
> in the world, just thirteen account for more than half the world's
> population:
>
> 1) Mandarin
> 2) Spanish
> 3) English
> 4) Hindi
> 5) Arabic
> 6) Portuguese
> 7) Bengali
> 8) Russian
> 9) Japanese
> 10) Punjabi
> 11) German
> 12) Javanese
> 13) Wu
>
> adding up to 51%. The next thirteen bring the total to 64%.

Where did that info come from? And more importantly, what does it
count? Is that people's first language, or all languages known, or
what? A bit of Googling brought me to a Wikipedia page [1] which
quotes a similar figure of thirteen languages; that's talking about
native speakers, and is talking about native speakers. But that may
not be the most useful definition here.

An alternative useful definition is "accessibility": if you
communicate a message in Mandarin and English, a large proportion of
humans will be capable of understanding that message. Does it take the
above thirteen to exceed 50% of the world by that definition? Or
wording it another way, is there no set of twelve or less languages
which will reach 50% of the world? There's another Wikipedia page [2]
that tries to estimate total number of speakers, but it's nearly
impossible to get any sort of accurate figure; it puts Mandarin at
somewhere over a billion people, and English as another billion or so;
that's coming up toward 50% right there (say, 1.5b each is 3b, out of
a world population of 7b). Ball-park figures, those two plus Spanish
(another half billion or so) would pretty much hit your half mark.

I've no idea what point I'm trying to make here. Just poking around
with numbers. :)

ChrisA

[1] https://en.wikipedia.org/wiki/List_of_languages_by_number_of_native_speakers
[2] https://en.wikipedia.org/wiki/List_of_languages_by_total_number_of_speakers


From roy at panix.com  Sun Mar 30 08:08:52 2014
From: roy at panix.com (Roy Smith)
Date: Sun, 30 Mar 2014 08:08:52 -0400
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <j8-dne29t9g2VarOnZ2dnUVZ_qSdnZ2d@giganews.com>
Message-ID: <roy-CAE77A.08085230032014@news.panix.com>

In article <j8-dne29t9g2VarOnZ2dnUVZ_qSdnZ2d at giganews.com>,
 Larry Hudson <orgnut at yahoo.com> wrote:

> I believe the point is your generalized use of "American".  After all, 
> Mexicans are Americans too, as well as Canadians, Peruvians and ...
> 
> Unfortunately, there is no good word for "USA-ian".

I believe Mexicans refer to us as "norteamericanos" in polite company.  
That's a little long for daily use, so more typically it's shortened to 
"gringo".


From roy at panix.com  Sun Mar 30 08:21:25 2014
From: roy at panix.com (Roy Smith)
Date: Sun, 30 Mar 2014 08:21:25 -0400
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
 <roy-346471.22394529032014@news.panix.com>
 <308493ad-d904-4897-8d7d-6f7780a6bb7d@googlegroups.com>
 <5337b4e4$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <roy-B1CF22.08212530032014@news.panix.com>

In article <5337b4e4$0$29994$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> I think Johannes got it right: boolean logic is easier to reason about 
> when there is a minimum of "not"s.

I used to do a lot of digital logic design.  In certain logic families, 
it's easier to build a NAND gate than an AND gate (and similarly, NOR is 
easier than OR).  This leads to lots of inverted logic.  Adding to the 
confusion, many designs would use "active low" logic, which means a 1 
was represented by a low voltage, and a 0 by a high voltage.  So, you 
quickly end up with gibberish like, "not active low clear nand not 
active low enable clock".  I'm glad I don't do that stuff any more.


From python at mrabarnett.plus.com  Sun Mar 30 09:58:11 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Sun, 30 Mar 2014 14:58:11 +0100
Subject: checking if two things do not equal None
In-Reply-To: <roy-B1CF22.08212530032014@news.panix.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
 <roy-346471.22394529032014@news.panix.com>
 <308493ad-d904-4897-8d7d-6f7780a6bb7d@googlegroups.com>
 <5337b4e4$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-B1CF22.08212530032014@news.panix.com>
Message-ID: <533822F3.5070407@mrabarnett.plus.com>

On 2014-03-30 13:21, Roy Smith wrote:
> In article <5337b4e4$0$29994$c3e8da3$5496439d at news.astraweb.com>,
>   Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>
>> I think Johannes got it right: boolean logic is easier to reason about
>> when there is a minimum of "not"s.
>
> I used to do a lot of digital logic design.  In certain logic families,
> it's easier to build a NAND gate than an AND gate (and similarly, NOR is
> easier than OR).  This leads to lots of inverted logic.  Adding to the
> confusion, many designs would use "active low" logic, which means a 1
> was represented by a low voltage, and a 0 by a high voltage.  So, you
> quickly end up with gibberish like, "not active low clear nand not
> active low enable clock".  I'm glad I don't do that stuff any more.
>
When you're building with discrete logic chips, NAND gates are useful
because you can use them as inverters too, which helps to keep the chip
count down.


From steve+comp.lang.python at pearwood.info  Sun Mar 30 11:22:45 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 30 Mar 2014 15:22:45 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <lgoh7j$otg$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
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 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
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 <lh5vq3$c1j$1@speranza.aioe.org>
Message-ID: <533836c4$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sat, 29 Mar 2014 03:21:29 -0500, Mark H Harris wrote:

> On 3/29/14 1:03 AM, Chris Angelico wrote:
>>
>> http://forum.ecomstation.ru/
>>
>> Prominent discussion forum, although that strives to be at least
>> partially bilingual in deference to those of us who are so backward as
>> to speak only English.
> 
>     Yes. Well, as the joke goes, if you're trilingual you speak three
> languages, if you're bilingual you speak two languages, if you're
> monolingual you're an American (well, that might go for Australia too,
> maybe). When whole continents speak the same language that tends to
> happen.

I think that the Qu?b?cois and Mexicans might object to your 
characterisation of North America as speaking a single language.

English is the primary lingua franca in various fields, such as aviation, 
diplomacy, trade and, yes, computing. But it's not the only lingua franca 
in common use: French and Spanish are the second and third most common 
languages used in international trade, and Arabic, Mandarin, Cantonese, 
Russian, and many others remain important regional and international 
lingua francas:

https://en.wikipedia.org/wiki/List_of_lingua_francas

English currently is the dominant international language, but it is not 
the only such language, and it's dominance is not so complete that other 
languages are second-class. One need only look at your spam folder, and 
see how much spam is sent in Chinese, Russian and other languages to 
realise that English hasn't even come close to taking over the planet yet.

But none of which is really relevant to the question on hand. When people 
from France, Germany, Russia, Brazil and Japan get together on the 
Internet, they probably write English. When they are writing for 
themselves, they typically write in French, Germany, Russian, Brazilian 
Portuguese, and Japan.

http://blog.gmane.org/gmane.comp.python.brasil
http://blog.gmane.org/gmane.comp.accessibility.tanaguru
http://blog.gmane.org/gmane.comp.apache.discussion.russian

etc.


[...]
>     What I can tell you in my own experience, as an amateur radio
> operator (W0MHH, general class) who has communicated all over the earth
> (even to Soviet Russia), all my computer|radio comm was in English using
> Morse code sets, Latin characters, and ASCII.  No one ever asked me to
> comm in Russian, or French, nor Italian, nor Tswana...

Are you aware that the astronauts on the International Space Station have 
to be fluent in Russian? Hardly surprising, since the Soyuz rockets used 
to get to the ISS are made by Russians, maintained by Russians, and 
launched by Russians. All the controls and manuals are written in 
Russian. One might almost say that the lingua franca of space travel is 
Russian.

You're experience suggests that the lingua franca of the amateur radio 
community is English. If you wanted to be an astronaut, you'd need to 
learn Russian. (Although I wonder whether the Chinese agree about that.) 
Whenever you have people from a broad range of languages getting together 
and needing to communicate, they need to agree on a common tongue. Often 
that's English. Often it is not.

http://www.arabo.com/

(I searched for "python", and got three hits: one in English and two in 
French.)


> By the way, in my view, 1991 is very recently; 

In 1991, there was no wireless, no mobile computing, hardly any public 
Internet outside of the universities. It was before the Eternal 
September, and only a few years after the Great Renaming. Python had just 
been released for the first time, and Windows 3.1 hadn't been (although 
3.0 had). There was no Netscape, no Mosaic graphical web browsers. Steve 
Jobs hadn't returned to Apple yet, Apple was still losing money and mind-
share, and Google didn't even exist. It was a different era.

1991 is 23 years ago. In "computer years", I consider that almost eight 
generations, about the same as 160 years in human terms. 


> from a computer historical standpoint too. I mean, think
> about it, computers have only existed since late 1940s and only in their
> modern context since about 1989. I didn't really start using unicode
> until about 5 years ago; python has only really used it since python3.
> right?

No. Python 2.2 introduced Unicode.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From ian.g.kelly at gmail.com  Sun Mar 30 12:03:47 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 30 Mar 2014 10:03:47 -0600
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <533836c4$0$29994$c3e8da3$5496439d@news.astraweb.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
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 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <533836c4$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALwzidnp1Gx=pDOKBMRpbxdP62dX=n4GR+7rmdZbRiT0q+tGnw@mail.gmail.com>

On Mar 30, 2014 9:26 AM, "Steven D'Aprano" <
steve+comp.lang.python at pearwood.info> wrote:
>
> On Sat, 29 Mar 2014 03:21:29 -0500, Mark H Harris wrote:
> > from a computer historical standpoint too. I mean, think
> > about it, computers have only existed since late 1940s and only in their
> > modern context since about 1989. I didn't really start using unicode
> > until about 5 years ago; python has only really used it since python3.
> > right?
>
> No. Python 2.2 introduced Unicode.

Python 2.0 if the PEP 100 metadata is accurate.
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From steve+comp.lang.python at pearwood.info  Sun Mar 30 12:22:45 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 30 Mar 2014 16:22:45 GMT
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8369.1395437459.18130.python-list@python.org>
 <a0403642-c384-4623-bbfd-77c48285ec96@googlegroups.com>
 <mailman.8377.1395456097.18130.python-list@python.org>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
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 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
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 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
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Message-ID: <533844d5$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Sun, 30 Mar 2014 01:22:55 -0500, Mark H Harris wrote:

> On 3/29/14 12:53 PM, Steven D'Aprano wrote:
>> People have had localised code pages, and localised keyboards to enter
>> characters in those code pages, for up to 30 years, if not longer.
> 
>     Nobody is arguing otherwise, Steven. 

It certainly seemed like you were.


> Having a code page for a local
> language is not the same thing as having software that supports your
> local language code page!

Of course they're not the same, but localised software does exist. You're 
making the mistake of thinking that because you only see English-language 
software, no other software exists. But you are an English-speaker in an 
English-speaking country, of course nearly all the software you see is 
written for English speakers.

But if you were in Spain, the software you buy would be in Spanish:

http://www.sevenforums.com/general-discussion/123741-changing-language-
localization.html

More about localisation:

http://blogs.msdn.com/b/oldnewthing/archive/2012/07/26/10333558.aspx

http://support.apple.com/kb/HT4239?viewlocale=fr_FR&locale=fr_FR



 Software and code pages improved over time,
> but international communication (which is what I'm talking about) has
> always been done in English, using ASCII. 

That's simply not correct. Even if we limit "always" to mean "since World 
War Two", it's still wrong. IBM was localising their computers for non-
English markets before ASCII even existed, "code pages" was an IBM 
technology invented for EBCDIC-using mainframes before there were ASCII-
using PCs.

What is true is that English is the primary lingua franca on the 
Internet. But it's not the only one, and there are plenty of places on 
the Internet where people discuss things in their own language.


> Well except when Guido brought
> the ABC stuff to the states back in the day and had no way to do that
> except to fly himself (and the tape) personally.
>>
>> In some of those cases, the localisation was done by companies like
>> IBM, Microsoft and Apple, realising that if they wanted to sell
>> computers outside of the US, they needed to supply computers that were
>> localised to their market.
> 
>     Unfortunately that happened way late. And even then, international
> communication was still done (and is still done) in English.

And French. And Spanish. And Chinese. If you trade with most of Africa, 
knowing Arabic or French will probably be more useful than knowing 
English.


> Only until
> very recently (see my post to Chris) has unicode improved to the point
> where international comm can occur reliably enough (input, font, code
> points) to allow comm in languages other than English.

Unicode has little to do with the ability to communicate in languages 
other than English. If you want to communicate in Greek, you don't need 
Unicode, you just need both parties to agree to use ISO-8859-7. If you 
want to communicate in Japanese, you could use Shift-JIS, or various 
others.

Where Unicode comes into it is when you want to manage *mixed* 
communication. There's no way for me to include your ISO-8859-7 Greek 
text in my Shift-JIS Japanese document. I can use one, or the other, but 
not both. But with Unicode, I can use them both.


[...]
>     My point exactly. With the advent of the Internet, almost *all* comm
> is English with minor notable exceptions in today's environment.

Not even close to "almost all". Barely half of the Internet is English. 
If you only look in the English-speaking corners of the Internet, it is 
hardly surprising that you only see people speaking English.


Even at the high-point, English was only 80% of the Internet, 20% (that's 
*one in five* websites) was non-English:

http://www.theatlantic.com/past/docs/issues/2000/11/wallraff3.htm

That was a decade ago, and as predicted, the percentage of the Internet 
which uses English has plummeted as more non-English speakers have got on 
the 'net. Today, only 56% of the Internet is English:

http://w3techs.com/technologies/overview/content_language/all

That figure is based on the one million most popular websites. If you 
include *all* websites, you'll find the English percentage is even lower, 
and quite likely under 50%.

https://en.wikipedia.org/wiki/Languages_used_on_the_Internet

Some other points to consider: 

44% of WordPress sites are non-English:

http://venturebeat.com/2013/07/27/19-percent-of-the-web-runs-on-wordpress/

which is representative of the broader Internet. And since 2001, while 
the use of English on the Internet grew by 281%, other languages have 
grown much faster: 

- Spanish (743%)
- Chinese (1,277%)
- Russian (1,826%)
- Arabic (2,501%)


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From mtcplumb at googlemail.com  Sun Mar 30 15:05:18 2014
From: mtcplumb at googlemail.com (mtcplumb at googlemail.com)
Date: Sun, 30 Mar 2014 12:05:18 -0700 (PDT)
Subject: writing reading from a csv or txt file
Message-ID: <9023eae9-f814-40ac-9b84-043214e6b28f@googlegroups.com>

Hi I have 3 csv files with a list of 5 items in each.
rainfall in mm, duration time,time of day,wind speed, date.
I am trying to compare the files. cutting out items in list list. ie:- 
first file (rainfall2012.csv)rainfall, duration,time of day,wind speed,date.
first file (rainfall2013.csv)rainfall, duration,time of day,wind speed,date.
I would like to pick out maybe rainfalls and duration's and measure against say years. 
I would like to very the items from the rows. 
could you please advise me where i can find such information. or book, textbook.



From jsf80238 at gmail.com  Sun Mar 30 16:19:48 2014
From: jsf80238 at gmail.com (Jason Friedman)
Date: Sun, 30 Mar 2014 14:19:48 -0600
Subject: writing reading from a csv or txt file
In-Reply-To: <9023eae9-f814-40ac-9b84-043214e6b28f@googlegroups.com>
References: <9023eae9-f814-40ac-9b84-043214e6b28f@googlegroups.com>
Message-ID: <CANy1k1j9=U8zOf9e=-acNtr4SnAGbznA4VrO1TqWE5j_XnKV_Q@mail.gmail.com>

>
> I am trying to compare the files. cutting out items in list list. ie:-
> first file (rainfall2012.csv)rainfall, duration,time of day,wind
> speed,date.
> first file (rainfall2013.csv)rainfall, duration,time of day,wind
> speed,date.
> I would like to pick out maybe rainfalls and duration's and measure
> against say years.
>
> Could you show us the first, say, three rows from each file, plus what you
would like the first three or six lines of output to be?
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From jcasale at activenetwerx.com  Sun Mar 30 16:21:32 2014
From: jcasale at activenetwerx.com (Joseph L. Casale)
Date: Sun, 30 Mar 2014 20:21:32 +0000
Subject: writing reading from a csv or txt file
In-Reply-To: <9023eae9-f814-40ac-9b84-043214e6b28f@googlegroups.com>
References: <9023eae9-f814-40ac-9b84-043214e6b28f@googlegroups.com>
Message-ID: <2230b359aade4572b3f4b3214373d7e7@exch.activenetwerx.com>

> Hi I have 3 csv files with a list of 5 items in each.
> rainfall in mm, duration time,time of day,wind speed, date.
> I am trying to compare the files. cutting out items in list list. ie:-
> first file (rainfall2012.csv)rainfall, duration,time of day,wind speed,date.
> first file (rainfall2013.csv)rainfall, duration,time of day,wind speed,date.
> I would like to pick out maybe rainfalls and duration's and measure against
> say years.
> I would like to very the items from the rows.
> could you please advise me where i can find such information. or book,
> textbook.

How about we help you here..

So if you want to compare by year, you want to read all the rows in and perform
some math, because I can't help myself, I push this into sqlite at least but that's
probably overkill for you (besides the limitless benefits:)). You want to store some
state while you iterate over each row in the csv, appending data, then finally performing
some statistical math on the collection.

You will do this for each file, then finally aggregate your results.

jlc


From gary.herron at islandtraining.com  Sun Mar 30 16:26:55 2014
From: gary.herron at islandtraining.com (Gary Herron)
Date: Sun, 30 Mar 2014 13:26:55 -0700
Subject: writing reading from a csv or txt file
In-Reply-To: <9023eae9-f814-40ac-9b84-043214e6b28f@googlegroups.com>
References: <9023eae9-f814-40ac-9b84-043214e6b28f@googlegroups.com>
Message-ID: <53387E0F.3010409@islandtraining.com>

On 03/30/2014 12:05 PM, mtcplumb at googlemail.com wrote:
> Hi I have 3 csv files with a list of 5 items in each.
> rainfall in mm, duration time,time of day,wind speed, date.
> I am trying to compare the files. cutting out items in list list. ie:-
> first file (rainfall2012.csv)rainfall, duration,time of day,wind speed,date.
> first file (rainfall2013.csv)rainfall, duration,time of day,wind speed,date.
> I would like to pick out maybe rainfalls and duration's and measure against say years.
> I would like to very the items from the rows.
> could you please advise me where i can find such information. or book, textbook.
>

How is this a Python question?

There is a standard  module included with Python for reading CSV files.  
Would you like to know how to use that?  You can find documentation on 
it here:
     http://docs.python.org/3/library/csv.html

Gary Herron


From greg.ewing at canterbury.ac.nz  Sun Mar 30 18:48:21 2014
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Mon, 31 Mar 2014 11:48:21 +1300
Subject: checking if two things do not equal None
In-Reply-To: <roy-B1CF22.08212530032014@news.panix.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <5337195f$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh7cb4$ntu$2@news.albasani.net> <roy-B5E8CC.17072029032014@news.panix.com>
 <53377b9e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <mailman.8709.1396145720.18130.python-list@python.org>
 <roy-346471.22394529032014@news.panix.com>
 <308493ad-d904-4897-8d7d-6f7780a6bb7d@googlegroups.com>
 <5337b4e4$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <roy-B1CF22.08212530032014@news.panix.com>
Message-ID: <bprl9hF9opU1@mid.individual.net>

Roy Smith wrote:
> Adding to the 
> confusion, many designs would use "active low" logic, which means a 1 
> was represented by a low voltage, and a 0 by a high voltage.  So, you 
> quickly end up with gibberish like, "not active low clear nand not 
> active low enable clock".

There are ways of dealing with that in schematic diagrams.
For exammple, if you have two active-low signals A and B
and want to express "A is active or B is active", you
draw an OR gate symbol with inversion circles on the
inputs. That's equivalent to a NAND gate, but makes the
intention clear.

Schematics drawn that way are much easier to follow than
ones that only use the inverted-output versions of the
symbols.

-- 
Greg


From rhodri at wildebst.org.uk  Sun Mar 30 18:57:30 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Sun, 30 Mar 2014 23:57:30 +0100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <j8-dne29t9g2VarOnZ2dnUVZ_qSdnZ2d@giganews.com>
 <5337f57d$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <op.xdj4p4sx5079vu@gnudebeest>

On Sun, 30 Mar 2014 11:44:13 +0100, Steven D'Aprano  
<steve+comp.lang.python at pearwood.info> wrote:

> On Sun, 30 Mar 2014 00:32:58 -0700, Larry Hudson wrote:
>
>> Unfortunately, there is no good word for "USA-ian".  "United States
>> Citizen" is too long and awkward and "United Statesian" is ridiculous.
>> The common usage of "American" for this is at best ambiguous, and
>> definitely inaccurate (as well as chauvinistic, and rather insulting to
>> other North and South Americans outside the US).
>
> Among fans of the British writer Terry Pratchett, the usual term is
> Merkins. Including among Merkin fans.

Many of whom even know what a merkin is, and use the term anyway.

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From gouzounakis at hotmail.com  Sun Mar 30 19:16:07 2014
From: gouzounakis at hotmail.com (D. Xenakis)
Date: Sun, 30 Mar 2014 16:16:07 -0700 (PDT)
Subject: Examples of modern GUI python programms
Message-ID: <c168919b-5d38-46f8-b97f-91eb49867814@googlegroups.com>

Id like to ask.. do you know any modern looking GUI examples of windows software written in python? Something like this maybe: http://techreport.com/r.x/asus-x79deluxe/software-oc.jpg (or hopefully something like this android look: http://chromloop.com/wp-content/uploads/2013/07/Skype-4.0-Android-screenshot.jpg).
What i need is to develop an android looking program (entirelly in python) for windows, but dunno if this is possible (most propably is), and which tool between those would help me most: tkinter - wxpython - pyqt - pygtk .

Any examples and suggestions are most welcome.


From python at mrabarnett.plus.com  Sun Mar 30 19:20:24 2014
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 31 Mar 2014 00:20:24 +0100
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
In-Reply-To: <op.xdj4p4sx5079vu@gnudebeest>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <j8-dne29t9g2VarOnZ2dnUVZ_qSdnZ2d@giganews.com>
 <5337f57d$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <op.xdj4p4sx5079vu@gnudebeest>
Message-ID: <5338A6B8.2070304@mrabarnett.plus.com>

On 2014-03-30 23:57, Rhodri James wrote:
> On Sun, 30 Mar 2014 11:44:13 +0100, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>
>> On Sun, 30 Mar 2014 00:32:58 -0700, Larry Hudson wrote:
>>
>>> Unfortunately, there is no good word for "USA-ian".  "United States
>>> Citizen" is too long and awkward and "United Statesian" is ridiculous.
>>> The common usage of "American" for this is at best ambiguous, and
>>> definitely inaccurate (as well as chauvinistic, and rather insulting to
>>> other North and South Americans outside the US).
>>
>> Among fans of the British writer Terry Pratchett, the usual term is
>> Merkins. Including among Merkin fans.
>
> Many of whom even know what a merkin is, and use the term anyway.
>
Isn't that what some said it sounded like when George W Bush said it?

"My fellow 'mercns, ..."


From walterhurry at gmail.com  Sun Mar 30 20:39:24 2014
From: walterhurry at gmail.com (Walter Hurry)
Date: Mon, 31 Mar 2014 00:39:24 +0000 (UTC)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <j8-dne29t9g2VarOnZ2dnUVZ_qSdnZ2d@giganews.com>
 <5337f57d$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lhadfs$4sv$1@news.albasani.net>

Steven D'Aprano wrote:

> On Sun, 30 Mar 2014 00:32:58 -0700, Larry Hudson wrote:
>
>> Unfortunately, there is no good word for "USA-ian".  "United States
>> Citizen" is too long and awkward and "United Statesian" is ridiculous. 
>> The common usage of "American" for this is at best ambiguous, and
>> definitely inaccurate (as well as chauvinistic, and rather insulting to
>> other North and South Americans outside the US).
>
> Among fans of the British writer Terry Pratchett, the usual term is 
> Merkins. Including among Merkin fans.
>
Tom Sharpe was there first, I think.
By the way, his books are hilarious.


From torriem at gmail.com  Sun Mar 30 22:16:06 2014
From: torriem at gmail.com (Michael Torrie)
Date: Sun, 30 Mar 2014 20:16:06 -0600
Subject: Examples of modern GUI python programms
In-Reply-To: <c168919b-5d38-46f8-b97f-91eb49867814@googlegroups.com>
References: <c168919b-5d38-46f8-b97f-91eb49867814@googlegroups.com>
Message-ID: <5338CFE6.6050102@gmail.com>

On 03/30/2014 05:16 PM, D. Xenakis wrote:
> What i need is to develop an android looking program (entirelly in
> python) for windows, but dunno if this is possible (most propably
> is), and which tool between those would help me most: tkinter -
> wxpython - pyqt - pygtk .
> 
> Any examples and suggestions are most welcome.

Your best bet is to use PyQt.  I bet you can make some android-looking
UIs using QtQuick (Javascript) with a bit of Python glue.




From harrismh777 at gmail.com  Mon Mar 31 00:29:13 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sun, 30 Mar 2014 23:29:13 -0500
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>	<53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh5iqs$j0m$1@speranza.aioe.org>	<mailman.8683.1396069736.18130.python-list@python.org>	<53365F55.2040302@gmail.com>	<mailman.8688.1396073027.18130.python-list@python.org>	<lh5vq3$c1j$1@speranza.aioe.org>	<mailman.8690.1396107966.18130.python-list@python.org>	<lh8bej$n7b$1@speranza.aioe.org>	<5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh8enq$t7e$1@speranza.aioe.org>
 <5337f383$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lhaquo$e5j$1@speranza.aioe.org>

On 3/30/14 5:35 AM, Steven D'Aprano wrote:
> On Sun, 30 Mar 2014 01:48:27 -0500, Mark H Harris wrote:
>>      Don't be silly, Steven, it doesn't become you.
>
> Given the sorts of patronising, condescending things you insist are true
> about non-Americans, such as their supposed inability to communicate in
> their own language on the Internet, I wasn't sure.

    You just crossed the boundary from silly to asinine.


> 1) Mandarin
> 2) Spanish
> 3) English
> 4) Hindi
> 5) Arabic
> 6) Portuguese
> 7) Bengali
> 8) Russian
> 9) Japanese
> 10) Punjabi
> 11) German
> 12) Javanese
> 13) Wu
>
> adding up to 51%. The next thirteen bring the total to 64%.

    Where the heck did you get that!?!     ...wow.

> (Figures are, naturally, approximate and subject to change.)

    no doubt.

*wink*



From harrismh777 at gmail.com  Mon Mar 31 00:57:43 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Sun, 30 Mar 2014 23:57:43 -0500
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>	<53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh5iqs$j0m$1@speranza.aioe.org>	<mailman.8683.1396069736.18130.python-list@python.org>	<53365F55.2040302@gmail.com>	<mailman.8688.1396073027.18130.python-list@python.org>	<lh5vq3$c1j$1@speranza.aioe.org>	<mailman.8690.1396107966.18130.python-list@python.org>	<lh8bej$n7b$1@speranza.aioe.org>	<5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh8enq$t7e$1@speranza.aioe.org>
 <5337f383$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lhask6$hap$1@speranza.aioe.org>

On 3/30/14 5:35 AM, Steven D'Aprano wrote:

> Approximately 5% of the US population either do not speak English at all,
> or speak it poorly. That includes approximately half a million ASL
> speakers (American Sign Language, which is not a manual representation of
> English but an independent language in it's own right), the majority of
> whom are unable to speak or understand spoken English.

Steven, you have trolled us over to the left edge of outer left field 
all the way back at the fence, dude, seriously--- and then you dropped 
the ball. Geeeze... error.

My point at the beginning was that we need a universal unicode input 
device. Its time to think past US_104 and en_US.  Come in out of left field.

As long as I'm passing along my dreams to everyone, we also need a 
universal translator on the uptake. In other words, everyone inputs from 
a universal encoder, and every browser has the option of on-demand 
translation (or not). Its a little like google translate, but on-demand, 
and its standard, and it works everywhere with every language.

Everyone keys input in their own heart language (first, primary 
language) and then the internet browser allows for display of first 
language (if the coding is the same) and translates if the coding is 
different (all configurable of course). Yes, the apps are in the cloud.

What say you?  We all type in our own language, and everyone else gets 
to read it in their own language. Its kinda like the day of Pentecost 
(except that its print instead of audio).

marcus


From rosuav at gmail.com  Mon Mar 31 01:05:25 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 31 Mar 2014 16:05:25 +1100
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
In-Reply-To: <lhask6$hap$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
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 <53365F55.2040302@gmail.com>
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 <lh8bej$n7b$1@speranza.aioe.org>
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 <lh8enq$t7e$1@speranza.aioe.org>
 <5337f383$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhask6$hap$1@speranza.aioe.org>
Message-ID: <CAPTjJmrfzuk9J7hMrpRE0D-PxVKFLza31MX0b-76RrnBHQ01Mw@mail.gmail.com>

On Mon, Mar 31, 2014 at 3:57 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> As long as I'm passing along my dreams to everyone, we also need a universal
> translator on the uptake. In other words, everyone inputs from a universal
> encoder, and every browser has the option of on-demand translation (or not).
> Its a little like google translate, but on-demand, and its standard, and it
> works everywhere with every language.
>
> Everyone keys input in their own heart language (first, primary language)
> and then the internet browser allows for display of first language (if the
> coding is the same) and translates if the coding is different (all
> configurable of course). Yes, the apps are in the cloud.
>
> What say you?  We all type in our own language, and everyone else gets to
> read it in their own language. Its kinda like the day of Pentecost (except
> that its print instead of audio).

And Pentecost required direct intervention of the all-powerful God of
the universe. Any less, and you'll run into translation difficulties.
It certainly cannot be automated; even done manually by people expert
in both the source and target languages, translation is imperfect.

ChrisA


From harrismh777 at gmail.com  Mon Mar 31 01:23:46 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 31 Mar 2014 00:23:46 -0500
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<lgj4sp$7ed$1@speranza.aioe.org>	<532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>	<53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh5iqs$j0m$1@speranza.aioe.org>	<mailman.8683.1396069736.18130.python-list@python.org>	<53365F55.2040302@gmail.com>	<mailman.8688.1396073027.18130.python-list@python.org>	<lh5vq3$c1j$1@speranza.aioe.org>	<mailman.8690.1396107966.18130.python-list@python.org>	<lh8bej$n7b$1@speranza.aioe.org>
 <5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lhau51$jtt$1@speranza.aioe.org>

On 3/30/14 1:31 AM, Steven D'Aprano wrote:
> The most recent US census found there are 38.5 million people in the US
> who primarily speak Spanish, and 45 million who speak it as their first
> or second language. In comparison, there are only an estimated 11 million
> illegal immigrants (of which only 7 million is from Mexico).

The following link shows plenty of language stats (most of them differ 
from yours markedly; the estimates are just guesses really).

The main point of the link is the status on English as an official 
language.  28 out of 50 states have legislated English as the official 
language; meaning, that you either speak and write English, or you're 
going to have a really tough time participating in culture, business, 
government, and recreation.

http://en.wikipedia.org/wiki/Languages_of_the_United_States#Official_language_status


marcus




From harrismh777 at gmail.com  Mon Mar 31 01:33:01 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 31 Mar 2014 00:33:01 -0500
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
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 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
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 <mailman.8728.1396242328.18130.python-list@python.org>
Message-ID: <lhaumc$kv5$1@speranza.aioe.org>

On 3/31/14 12:05 AM, Chris Angelico wrote:

>> What say you?  We all type in our own language, and everyone else gets to
>> read it in their own language. Its kinda like the day of Pentecost (except
>> that its print instead of audio).
>
> And Pentecost required direct intervention of the all-powerful God of
> the universe. Any less, and you'll run into translation difficulties.
> It certainly cannot be automated; even done manually by people expert
> in both the source and target languages, translation is imperfect.

Truth.   Well, like I said, its a dream.  And, we are finally at that 
point in time &space (fast computers, elegant programming languages, 
network, cloud apps, desire) where I think we could tackle universal 
translation.

On the other hand, would it be easier to simply move everyone to a 
neutral lingua franca?  For instance, lets say, biblical Greek.  In 
other words, the entire world learns a new (dead) language. Then, we all 
move forward speaking ONE language and we forget the translation thing 
altogether?

The reason that won't work is that everyone needs their heart language 
(as what it means to be human, and as what it means to be 'them'). How 
we speak is how we think, and feel. Its a conundrum for sure.

marcus



From rosuav at gmail.com  Mon Mar 31 01:44:56 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 31 Mar 2014 16:44:56 +1100
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
In-Reply-To: <lhau51$jtt$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>
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 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
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Message-ID: <CAPTjJmq-EKG+g+gfoxWnynoguWd0FCW3LeLheWYUvnXP-=1LvQ@mail.gmail.com>

On Mon, Mar 31, 2014 at 4:23 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
>
> The main point of the link is the status on English as an official language.
> 28 out of 50 states have legislated English as the official language;
> meaning, that you either speak and write English, or you're going to have a
> really tough time participating in culture, business, government, and
> recreation.
>
> http://en.wikipedia.org/wiki/Languages_of_the_United_States#Official_language_status

Considering how much is done to ensure that illiterate people can
still comprehend critical information (important signage, warnings,
traffic directions, etc, etc, etc), I think we can assume that someone
who speaks some language other than English will still manage to do a
lot of things. Plus, plenty of official documents are available in
many languages; the legislated "official language" just means that the
English version is the only one that is guaranteed to be there. Go to
any one of the states you've mentioned, where English is the sole
official language, and pick up any government form - something fairly
important, like applying for a passport or something. How many
languages is it available in? They might all be on the same form, or
maybe you have to explicitly request it in Spanish, but I expect it'll
be translated into several non-official languages for the convenience
of those whose English isn't as good as their (switch to GLaDOS voice)
Insert Subject Native Language Here (switch voice back).

But none of this has anything to do with the original point, namely
that there are people who communicate in other languages. Even if you
have to learn English for the sake of official documents, you won't
necessarily want to chat with your friends in English. If you pick up
the phone and talk to someone, you can use whatever language you want;
if you switch to email, chances are you still can. And that's
something that's been true since the dawn of email, which predates
Unicode by a slight margin... of a decade or so.

ChrisA


From metaliobovinus at gmail.com  Mon Mar 31 01:47:32 2014
From: metaliobovinus at gmail.com (Metallicow)
Date: Sun, 30 Mar 2014 22:47:32 -0700 (PDT)
Subject: Examples of modern GUI python programms
In-Reply-To: <mailman.8727.1396232185.18130.python-list@python.org>
References: <c168919b-5d38-46f8-b97f-91eb49867814@googlegroups.com>
 <mailman.8727.1396232185.18130.python-list@python.org>
Message-ID: <dc3dc297-2e18-4272-ad65-b4ccf7ee65e8@googlegroups.com>

On Sunday, March 30, 2014 9:16:06 PM UTC-5, Michael Torrie wrote:
> On 03/30/2014 05:16 PM, D. Xenakis wrote:
> 
> > What i need is to develop an android looking program (entirelly in
> > python) for windows, but dunno if this is possible (most propably
> > is), and which tool between those would help me most: tkinter -
> 
> > wxpython - pyqt - pygtk .
> > 
> > Any examples and suggestions are most welcome.
> 
> Your best bet is to use PyQt.  I bet you can make some android-looking
> UIs using QtQuick (Javascript) with a bit of Python glue.

Well, I wouldn't exactly say that Qt is the way to go just yet...
The author needs to weigh the benefits of each toolkit and make a decision for themselves.

As far as Qt is concerned, it is a bit more geared towards mobile apps at this point in its python life.
It is a bit nicer with the animated stuff also.
wxPython on the other hand has way better community support than QT side and has been around longer, so that may be a consideration.
Tk is alright and bundled with python but requires more work than the others and isn't always native looking without a bit of extra work.

Overall if you are fine with using a GUI builder for the GUI framework, then QT has a nice put-it-all-together IDE.
If you are looking for a really customized(hand-tweakable) GUI with relative hassle, then I would recommend wxPython or if you know Tk this would be ok for the majority of stuff, but requires a bit more work.

Another thing to consider is that if you are actually wanting this to work on a android or mobile device QT would be a better choice. Especially if touch support is an option.
If you are only wanting it to look like android themed app, the other choices provide better long term benefits.

As far as pygtk, that fairs better with linux, and in my opinion could use some updates platform-wise rounding the bugs out overall.

My opinion would be wxPython if not actually using for a mobile, or PySide if you are. Both of these have acceptable licenses if you want to go commercial also without having to pay for commercial library usage.


From harrismh777 at gmail.com  Mon Mar 31 02:08:24 2014
From: harrismh777 at gmail.com (Mark H Harris)
Date: Mon, 31 Mar 2014 01:08:24 -0500
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>	<lgj4sp$7ed$1@speranza.aioe.org>	<532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lgoh7j$otg$1@speranza.aioe.org>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>	<53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh5iqs$j0m$1@speranza.aioe.org>	<mailman.8683.1396069736.18130.python-list@python.org>	<53365F55.2040302@gmail.com>	<mailman.8688.1396073027.18130.python-list@python.org>	<lh5vq3$c1j$1@speranza.aioe.org>
 <533836c4$0$29994$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <lhb0on$pcj$1@speranza.aioe.org>

On 3/30/14 10:22 AM, Steven D'Aprano wrote:
> In 1991, there was no wireless, no mobile computing, hardly any public
> Internet outside of the universities. It was before the Eternal
> September, and only a few years after the Great Renaming.

    I was using arpanet since the late 1970s.

> Python had just
> been released for the first time, and Windows 3.1 hadn't been (although
> 3.0 had). There was no Netscape, no Mosaic graphical web browsers. Steve
> Jobs hadn't returned to Apple yet, Apple was still losing money and mind-
> share, and Google didn't even exist. It was a different era.

    Command line all the way babe... uuencode uudecode base64  whoohoo.

    ftp, and all the rest...


> 1991 is 23 years ago. In "computer years", I consider that almost eight
> generations, about the same as 160 years in human terms.

    Bologna, Oscar Meyer Bologna, USDA Prime.  That's just plain silly. 
Yes, a lot of things have happened since 1991, but 1991 was yesterday; 
and in the big scheme of things, not much really has happened (oh, yeah, 
smaller and faster; Moores law moves forward, so what?)  We're still 
using von Nuemann processors, we're still using all the same stupid 
programming tricks; the only thing that has changed is that computers 
use a fraction of the power they did, they are very tiny, and they are 
very fast. so what?  We have unicode!  yeahhhh. ASCII is dead. Microsoft 
is dying. Gun/Linux rules. I still program in BASIC at least once a 
week, and we all still have trouble communicating around the globe.

>> I didn't really start using unicode
>> until about 5 years ago; python has only really used it since python3.
>> right?
>
> No. Python 2.2 introduced Unicode.

I didn't ask when it was introduced, I asked when it became useful? 
Python was experimenting with unicode in version 2.  It became more 
fully useful in version 3. I didn't use it in version 2--- way too 
frustrating.

Unicode in python3.x is (mostly) working correctly. Congratulations to 
all who worked on it, hat is off.  The problem with unicode is that it 
is just a specification. The consortium cannot force or code anything. 
They control the scripts and make the specifications. It is left to 
*everyone* else to implement. And not everyone is taking on that task 
with the same gusto, if you follow my meaning.


marcus



From rosuav at gmail.com  Mon Mar 31 02:47:20 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 31 Mar 2014 17:47:20 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <lhb0on$pcj$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
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 <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
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 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
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 <53365F55.2040302@gmail.com>
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 <lh5vq3$c1j$1@speranza.aioe.org>
 <533836c4$0$29994$c3e8da3$5496439d@news.astraweb.com>
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Message-ID: <CAPTjJmoRLdgOzd0MzMaCWAkP7RU382BWA+KaNmLNwXnmXVnYCA@mail.gmail.com>

On Mon, Mar 31, 2014 at 5:08 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> Unicode in python3.x is (mostly) working correctly. Congratulations to all
> who worked on it, hat is off.  The problem with unicode is that it is just a
> specification. The consortium cannot force or code anything. They control
> the scripts and make the specifications. It is left to *everyone* else to
> implement. And not everyone is taking on that task with the same gusto, if
> you follow my meaning.

Considering that Pike's native double-quoted string type stored true
Unicode (not UTF-16, not eight-bit, the full Unicode range) back in
1998, you're quite correct in saying that some take on that task with
more enthusiasm than others. Of course, that exact same fact does tell
against your other and more important point, namely that people were
unable to speak non-English to each other until very recently. Good
luck.

ChrisA


From ben+python at benfinney.id.au  Mon Mar 31 02:53:55 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 31 Mar 2014 17:53:55 +1100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
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 <lh5iqs$j0m$1@speranza.aioe.org>
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 <53365F55.2040302@gmail.com>
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 <lh5vq3$c1j$1@speranza.aioe.org>
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 <lhb0on$pcj$1@speranza.aioe.org>
Message-ID: <85a9c6n9j0.fsf@benfinney.id.au>

Mark, you are demonstrating a habit of making sweeping pronouncements
and assertions; and then, when those statements are challenged, you
act as though you never said them.

Here's a characteristic example:

Mark H Harris <harrismh777 at gmail.com> writes:

> On 3/30/14 10:22 AM, Steven D'Aprano wrote:
> > Mark H Harris <harrismh777 at gmail.com> writes:
> >> I didn't really start using unicode until about 5 years ago; python
> >> has only really used it since python3. right?
> >
> > No. Python 2.2 introduced Unicode.
>
> I didn't ask when it was introduced, I asked when it became useful?

That's clearly not what you asked, in the material you quoted above; and
Steven's answer to your actual false assertion is entirely appropriate.

There are many other examples in this thread, but I'm not seeking to
catalogue them; merely to show an example of what I'm observing.

I hope you can see that this behaviour quickly leads many people to
quite reasonably disregard your assertions in general, and even to
ignore you altogether. Do you think you can tone down the rhetoric and
perhaps stand by the statements you actually make?

-- 
 \     ?Injustice is relatively easy to bear; what stings is justice.? |
  `\                                                 ?Henry L. Mencken |
_o__)                                                                  |
Ben Finney



From rustompmody at gmail.com  Mon Mar 31 03:36:17 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 31 Mar 2014 00:36:17 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <mailman.8731.1396248859.18130.python-list@python.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
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 <87ior3w740.fsf@elektro.pacujo.net> <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me> <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <533836c4$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhb0on$pcj$1@speranza.aioe.org>
 <mailman.8731.1396248859.18130.python-list@python.org>
Message-ID: <a6d292ab-964a-4055-b902-a3ab7d90196e@googlegroups.com>

On Monday, March 31, 2014 12:23:55 PM UTC+5:30, Ben Finney wrote:
> Mark, you are demonstrating a habit of making sweeping pronouncements
> and assertions; and then, when those statements are challenged, you
> act as though you never said them.

> Here's a characteristic example:

> Mark H Harris writes:

> > On 3/30/14 10:22 AM, Steven D'Aprano wrote:
> > > Mark H Harris  writes:
> > >> I didn't really start using unicode until about 5 years ago; python
> > >> has only really used it since python3. right?
> > > No. Python 2.2 introduced Unicode.
> > I didn't ask when it was introduced, I asked when it became useful?

> That's clearly not what you asked, in the material you quoted above; and
> Steven's answer to your actual false assertion is entirely appropriate.

> There are many other examples in this thread, but I'm not seeking to
> catalogue them; merely to show an example of what I'm observing.

> I hope you can see that this behaviour quickly leads many people to
> quite reasonably disregard your assertions in general, and even to
> ignore you altogether. Do you think you can tone down the rhetoric and
> perhaps stand by the statements you actually make?

I wonder...
Is there some Unicode-corollary to Godwin's law? Something like:

"Whenever people discuss unicode long enough they start talking rubbish."

Not very surprising given that unicode is related to human languages
and human languages willy-nilly are connected to politics.

It would be neat if we could stick to the 'uni(versal)' (aka math, music etc) 
aspect of unicode more and the 'needs localization' aspect less.


From jeremy at jeremysanders.net  Mon Mar 31 03:56:59 2014
From: jeremy at jeremysanders.net (Jeremy Sanders)
Date: Mon, 31 Mar 2014 09:56:59 +0200
Subject: checking if two things do not equal None
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
Message-ID: <lhb73s$l9l$1@ger.gmane.org>

contact.trigon at gmail.com wrote:

> if (a, b) != (None, None):
> or
> if a != None != b:
> 
> Preference? Pros? Cons? Alternatives?

I couldn't see anyone else give this, but I like

if None not in (a, b):
 pass

Jeremy




From breamoreboy at yahoo.co.uk  Mon Mar 31 04:31:00 2014
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 31 Mar 2014 09:31:00 +0100
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
In-Reply-To: <lhask6$hap$1@speranza.aioe.org>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>	<mailman.8440.1395651801.18130.python-list@python.org>	<lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net>	<lgqgn7$bpd$1@speranza.aioe.org>	<mailman.8478.1395710470.18130.python-list@python.org>	<lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me>	<lh1h1f$ov3$1@speranza.aioe.org>	<5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh4ouu$n8l$1@speranza.aioe.org>	<53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh5iqs$j0m$1@speranza.aioe.org>	<mailman.8683.1396069736.18130.python-list@python.org>	<53365F55.2040302@gmail.com>	<mailman.8688.1396073027.18130.python-list@python.org>	<lh5vq3$c1j$1@speranza.aioe.org>	<mailman.8690.1396107966.18130.python-list@python.org>	<lh8bej$n7b$1@speranza.aioe.org>	<5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>	<lh8enq$t7e$1@speranza.aioe.org>
 <5337f383$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhask6$hap$1@speranza.aioe.org>
Message-ID: <lhb946$dp4$1@ger.gmane.org>

On 31/03/2014 05:57, Mark H Harris wrote:
> On 3/30/14 5:35 AM, Steven D'Aprano wrote:
>
>> Approximately 5% of the US population either do not speak English at all,
>> or speak it poorly. That includes approximately half a million ASL
>> speakers (American Sign Language, which is not a manual representation of
>> English but an independent language in it's own right), the majority of
>> whom are unable to speak or understand spoken English.
>
> Steven, you have trolled us over to the left edge of outer left field
> all the way back at the fence, dude, seriously--- and then you dropped
> the ball. Geeeze... error.
>

Is it safe to assume that's a reference from a sport that essentially 
only gets played in the USA so you have a World Series?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com




From wxjmfauth at gmail.com  Mon Mar 31 04:32:42 2014
From: wxjmfauth at gmail.com (wxjmfauth at gmail.com)
Date: Mon, 31 Mar 2014 01:32:42 -0700 (PDT)
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
In-Reply-To: <a6d292ab-964a-4055-b902-a3ab7d90196e@googlegroups.com>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org>
 <87ior3w740.fsf@elektro.pacujo.net> <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org>
 <lgtsga$2ei$1@dont-email.me> <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <533836c4$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhb0on$pcj$1@speranza.aioe.org>
 <mailman.8731.1396248859.18130.python-list@python.org>
 <a6d292ab-964a-4055-b902-a3ab7d90196e@googlegroups.com>
Message-ID: <1d9cec81-2548-49aa-be4a-4857fdccb9e7@googlegroups.com>

Unicode...

Interesting reading.

jmf


From marko at pacujo.net  Mon Mar 31 04:39:12 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 31 Mar 2014 11:39:12 +0300
Subject: OFF TOPIC Spanish in the USA
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhau51$jtt$1@speranza.aioe.org>
Message-ID: <87a9c6vk27.fsf@elektro.pacujo.net>

Mark H Harris <harrismh777 at gmail.com>:

> The main point of the link is the status on English as an official
> language. 28 out of 50 states have legislated English as the official
> language; meaning, that you either speak and write English, or you're
> going to have a really tough time participating in culture, business,
> government, and recreation.

What does "official language" mean?

Finland has two official languages: Finnish and Swedish. It means you
are guaranteed to get state services in both languages. At municipal
level, you might get guarantees in one or both of the languages
depending on census data.

In California, OTOH, it's the other way around: English being official
means you are guaranteed *not* to get services in languages other than
English. If a government social worker speaks Spanish and the customer
only knows Spanish, the social worker is not legally allowed to use
Spanish to conduct their business. In Finland, no government worker is
disallowed from using any language they deem useful in their work.


Marko


From sturla.molden at gmail.com  Mon Mar 31 04:48:33 2014
From: sturla.molden at gmail.com (Sturla Molden)
Date: Mon, 31 Mar 2014 08:48:33 +0000 (UTC)
Subject: Examples of modern GUI python programms
References: <dc3dc297-2e18-4272-ad65-b4ccf7ee65e8@googlegroups.com>
Message-ID: <1536365056417947084.883654sturla.molden-gmail.com@news.gmane.org>

Metallicow <metaliobovinus at gmail.com> wrote:

> My opinion would be wxPython if not actually using for a mobile, or
> PySide if you are. Both of these have acceptable licenses if you want to
> go commercial also without having to pay for commercial library usage.


If you are to distribute a program using LGPL software on AppStore or
Gopgle Play, then remember that the user must be allowed to relink the
program with anpther version of the library. That is an LGPL requirement. I
don't see how this requirement can be satisfied in this case. Thus, LGPL on
AppStore or Google Play is probably put of the question. At least on iOS,
the user cannot change what you put in an App bundle. This excludes
wxPython and PySide. Thus, the only viable cross-platform choices are
commercial PyQt + commercial Qt or tkinter. In case of iOS, PyObjC is also
an option. py2app will also be useful for creating App bundles on iOS.

Sturla



From metaliobovinus at gmail.com  Mon Mar 31 05:33:11 2014
From: metaliobovinus at gmail.com (Metallicow)
Date: Mon, 31 Mar 2014 02:33:11 -0700 (PDT)
Subject: Examples of modern GUI python programms
In-Reply-To: <mailman.8736.1396255726.18130.python-list@python.org>
References: <dc3dc297-2e18-4272-ad65-b4ccf7ee65e8@googlegroups.com>
 <mailman.8736.1396255726.18130.python-list@python.org>
Message-ID: <db2ed73f-aa1f-42d6-abcd-0b7c29c95e1f@googlegroups.com>

On Monday, March 31, 2014 3:48:33 AM UTC-5, Sturla Molden wrote:
> If you are to distribute a program using LGPL software on AppStore or
> Gopgle Play, then remember that the user must be allowed to relink the
> program with anpther version of the library. That is an LGPL requirement. I
> don't see how this requirement can be satisfied in this case. Thus, LGPL on
> AppStore or Google Play is probably put of the question. At least on iOS,
> the user cannot change what you put in an App bundle. This excludes
> wxPython and PySide. Thus, the only viable cross-platform choices are
> commercial PyQt + commercial Qt or tkinter. In case of iOS, PyObjC is also
> an option. py2app will also be useful for creating App bundles on iOS.
> 
> Sturla

The OP didn't exactly detail what exactly was being looked for just
"python on windows" basically. So that part still hasn't been answered...
As far as wxPython, that is not LGPL, it is wxPython/wxWidgets which is fine for licensing your compiled app as however you want. 
Modifications to the library stuff for example is good in the fact with this that most all improvements(to the library-stuff) eventually work their way back in or have to be released GPL v2.

One would have to tool through the PySide agreement for their specifics, but as I recall it is exactly the same as Qt is, which makes sense. Riverbank/PyQt is not Qt, they are a separate entity, just to make that clear. The reason PySide was made was because Riverbank didn't want to license their bindings that same as Qt basically.

A lot depends on what you intend to do with "the" app and how many hoops you are willing to jump through license wise.

Just because a library is LGPL doesn't mean the authors code has to be depending on the circumstances. That just means usually you have to be able to provide the library code(and your mods to it) used.
If the author doesn't care about releasing his/her own source code, then just about any toolkit would be at the same level of "python on windows" for the most part.

It all depends on what the target for the app is. "Windows desktop?", "Windows Phone?", "MSW XBox?", etc...


From antoon.pardon at rece.vub.ac.be  Mon Mar 31 05:55:48 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Mon, 31 Mar 2014 11:55:48 +0200
Subject: unicode as valid naming symbols
In-Reply-To: <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
Message-ID: <53393BA4.2080305@rece.vub.ac.be>

On 27-03-14 17:22, Ian Kelly wrote:
> On Thu, Mar 27, 2014 at 9:28 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>>> Do you think that the ability to write this would be an improvement?
>>>
>>> import ?
>>> ? = ?.??
>>> ? = 5*?.??
>>> ? = ? - 1
>>> ??? = [?.??**?.?*?{?|?.?} for ? in ?.?]
>>> ?.??????(???)
>>
>>    Steven, you're killing me here; argument by analogy does not work!
> [  ------ 8< ---------- ]
> One of the things that Python is widely known for is its readability.
> Allowing symbols such as ? to denote identifiers may be quite
> expressive and appreciable to the person writing the code. However it
> damages readability considerably, as seen in Steven's example above.
> Personally I'm not interested in having to maintain another
> programmer's code that arbitrarily uses ? as a timer function, ? as
> intersection or ? as a matrix constructor.

I don't find Steven's example convincing. Sure it can be used in a way
that damages readability considerably however lots of things in python
can be abused in a way that damages readability considerably.

That you are not interested in having to maintain someone's code who
would use such symbols is irrelevant. IIRC people have used the exact
same kind of argument against decorators and the if-else operator.

It seems we are all consenting adults until someone doesn't like the
idea how it might influence his job. In that case it shouldn't be
allowed.

-- 
Antoon Pardon



From nispray at gmail.com  Mon Mar 31 07:03:55 2014
From: nispray at gmail.com (Wesley)
Date: Mon, 31 Mar 2014 04:03:55 -0700 (PDT)
Subject: Python IM server
Message-ID: <cd39e1e2-6580-47a6-8cc6-d753f4c0200d@googlegroups.com>

Hi all,
  I want to develop a instant message server, simply has user and group entity.

Is there any better existing open-source one?
Thus I can download and have a look.

Thanks.
Wesley


From jamiemitchell1604 at gmail.com  Mon Mar 31 07:29:15 2014
From: jamiemitchell1604 at gmail.com (Jamie Mitchell)
Date: Mon, 31 Mar 2014 04:29:15 -0700 (PDT)
Subject: Line of best fit
Message-ID: <0fb15100-15e8-46d6-a38f-b187c7012e62@googlegroups.com>

I am new to python so apologies for the ignorance with this question.

How would I apply a line of best fit to a plot?

My data are netCDF4 data files and this is essentially what I have done so far:

swh1=netCDF4.Dataset('filename','r')
hs1=swh1.variables['hs']

swh2=netCDF4.Dataset('filename'.'r')
hs2=swh2.variables['hs']

plt.plot(hs1,hs2,'.')

Cheers,

Jamie


From ned at nedbatchelder.com  Mon Mar 31 07:33:11 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Mon, 31 Mar 2014 07:33:11 -0400
Subject: OFF TOPIC Spanish in the USA
In-Reply-To: <87a9c6vk27.fsf@elektro.pacujo.net>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhau51$jtt$1@speranza.aioe.org> <87a9c6vk27.fsf@elektro.pacujo.net>
Message-ID: <lhbjpm$9an$1@ger.gmane.org>

On 3/31/14 4:39 AM, Marko Rauhamaa wrote:
> Mark H Harris <harrismh777 at gmail.com>:
>
>> The main point of the link is the status on English as an official
>> language. 28 out of 50 states have legislated English as the official
>> language; meaning, that you either speak and write English, or you're
>> going to have a really tough time participating in culture, business,
>> government, and recreation.
>
> What does "official language" mean?
>
> Finland has two official languages: Finnish and Swedish. It means you
> are guaranteed to get state services in both languages. At municipal
> level, you might get guarantees in one or both of the languages
> depending on census data.
>
> In California, OTOH, it's the other way around: English being official
> means you are guaranteed *not* to get services in languages other than
> English. If a government social worker speaks Spanish and the customer
> only knows Spanish, the social worker is not legally allowed to use
> Spanish to conduct their business. In Finland, no government worker is
> disallowed from using any language they deem useful in their work.

Can I politely suggest that we just end this discussion?  The thread has 
been properly marked as OFF TOPIC, and it is now squarely in areas that 
are 1) politically contentious, 2) wildly subjective, 3) none of our 
areas of expertise.  No good can come from continuing.

--Ned.

>
>
> Marko
>


-- 
Ned Batchelder, http://nedbatchelder.com



From roy at panix.com  Mon Mar 31 08:16:30 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 31 Mar 2014 08:16:30 -0400
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <dcd72881-7ee2-4bc3-90ab-7912b4bea05b@googlegroups.com>
 <lgj4sp$7ed$1@speranza.aioe.org>
 <532d5bd9$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <533836c4$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhb0on$pcj$1@speranza.aioe.org>
Message-ID: <roy-288B0B.08163031032014@news.panix.com>

In article <lhb0on$pcj$1 at speranza.aioe.org>,
 Mark H Harris <harrismh777 at gmail.com> wrote:

> On 3/30/14 10:22 AM, Steven D'Aprano wrote:
> > In 1991, there was no wireless, no mobile computing, hardly any public
> > Internet outside of the universities. It was before the Eternal
> > September, and only a few years after the Great Renaming.
> 
>     I was using arpanet since the late 1970s.
> 
> > Python had just
> > been released for the first time, and Windows 3.1 hadn't been (although
> > 3.0 had). There was no Netscape, no Mosaic graphical web browsers. Steve
> > Jobs hadn't returned to Apple yet, Apple was still losing money and mind-
> > share, and Google didn't even exist. It was a different era.
> 
>     Command line all the way babe... uuencode uudecode base64  whoohoo.

Remember when btoa/atob came out?  You got 32 bits of data in just 5 
characters.  Win!

Waiting for btou :-)

> Unicode in python3.x is (mostly) working correctly. Congratulations to 
> all who worked on it, hat is off.  The problem with unicode is that it 
> is just a specification. The consortium cannot force or code anything. 
> They control the scripts and make the specifications. It is left to 
> *everyone* else to implement.

My first introduction to unicode was a monster i18n makeover on a large 
C++ codebase.  For reasons I no longer remember, we ended up settling on 
utf-8 for "native" strings (with, of course, our own string class), but 
we were also using some library which was utf-16 internally (ICU4C, I 
think?).  So, we were constantly transcoding all over the place.  What a 
mess.


From roy at panix.com  Mon Mar 31 08:21:48 2014
From: roy at panix.com (Roy Smith)
Date: Mon, 31 Mar 2014 08:21:48 -0400
Subject: Line of best fit
References: <0fb15100-15e8-46d6-a38f-b187c7012e62@googlegroups.com>
Message-ID: <roy-157E04.08214831032014@news.panix.com>

In article <0fb15100-15e8-46d6-a38f-b187c7012e62 at googlegroups.com>,
 Jamie Mitchell <jamiemitchell1604 at gmail.com> wrote:

> I am new to python so apologies for the ignorance with this question.
> 
> How would I apply a line of best fit to a plot?

Python has nothing built-in which does that, but there are plenty of 
add-on modules which do those sorts of things.  One popular one is 
statsmodels (http://statsmodels.sourceforge.net/)

> plt.plot(hs1,hs2,'.')

Please tell us more about the environment you're working in.  I'm 
guessing from the fact that you're calling plt.plot(), that you've 
already got some add-on modules loaded.  Pandas, maybe?


From rosuav at gmail.com  Mon Mar 31 09:04:11 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 1 Apr 2014 00:04:11 +1100
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
In-Reply-To: <oioij9p4vr0h9e1k8eak0fod3sfesrj975@4ax.com>
References: <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhau51$jtt$1@speranza.aioe.org>
 <CAPTjJmq-EKG+g+gfoxWnynoguWd0FCW3LeLheWYUvnXP-=1LvQ@mail.gmail.com>
 <oioij9p4vr0h9e1k8eak0fod3sfesrj975@4ax.com>
Message-ID: <CAPTjJmrNRvk7p8RnQeONHy4=KV7erTEAa2MFvRZsKjM3rdjwsA@mail.gmail.com>

On Mon, Mar 31, 2014 at 11:41 PM, Dennis Lee Bieber
<wlfraed at ix.netcom.com> wrote:
> On Mon, 31 Mar 2014 16:44:56 +1100, Chris Angelico <rosuav at gmail.com>
> declaimed the following:
>
>>official language, and pick up any government form - something fairly
>>important, like applying for a passport or something. How many
>
>         Passport is a Federal form, not under State control.

Ehh, sorry, bad example then. (I'm not a Merkin, so I don't know what
you suffer under.) Pick something that is state-controlled instead.

ChrisA


From jfharden at gmail.com  Mon Mar 31 05:14:09 2014
From: jfharden at gmail.com (Jonathan Harden)
Date: Mon, 31 Mar 2014 10:14:09 +0100
Subject: Examples of modern GUI python programms
In-Reply-To: <c168919b-5d38-46f8-b97f-91eb49867814@googlegroups.com>
References: <c168919b-5d38-46f8-b97f-91eb49867814@googlegroups.com>
Message-ID: <CAFJhkDTFoXGAR3oZiniW-nx3kx7ncQLKWfQvPUvYgrgE4v0pdA@mail.gmail.com>

On 31 Mar 2014 00:21, "D. Xenakis" <gouzounakis at hotmail.com> wrote:
>

... Snip ...

> What i need is to develop an android looking program (entirelly in
python) for windows, but dunno if this is possible (most propably is), and
which tool between those would help me most: tkinter - wxpython - pyqt -
pygtk .
>
> Any examples and suggestions are most welcome.

While I've not used it much Kivy could be useful if you want it to look
Android like, with the added benefit that you can build for android as well.
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From moritz.beber at gmail.com  Mon Mar 31 07:50:53 2014
From: moritz.beber at gmail.com (Moritz Beber)
Date: Mon, 31 Mar 2014 13:50:53 +0200
Subject: Line of best fit
In-Reply-To: <0fb15100-15e8-46d6-a38f-b187c7012e62@googlegroups.com>
References: <0fb15100-15e8-46d6-a38f-b187c7012e62@googlegroups.com>
Message-ID: <CAFOFTpQR5r1Q2YcB7Vm-18WV5PGU_94YdsB408mBZKT=B4cPXA@mail.gmail.com>

None of these are in the standard library but why re-invent the wheel?

Using numpy:
http://docs.scipy.org/doc/numpy/reference/generated/numpy.polyfit.html

scipy:
http://docs.scipy.org/doc/scipy-0.13.0/reference/generated/scipy.stats.linregress.html

statsmodels:
http://statsmodels.sourceforge.net/devel/examples/notebooks/generated/ols.html


On Mon, Mar 31, 2014 at 1:29 PM, Jamie Mitchell <jamiemitchell1604 at gmail.com
> wrote:

> I am new to python so apologies for the ignorance with this question.
>
> How would I apply a line of best fit to a plot?
>
> My data are netCDF4 data files and this is essentially what I have done so
> far:
>
> swh1=netCDF4.Dataset('filename','r')
> hs1=swh1.variables['hs']
>
> swh2=netCDF4.Dataset('filename'.'r')
> hs2=swh2.variables['hs']
>
> plt.plot(hs1,hs2,'.')
>
> Cheers,
>
> Jamie
> --
> https://mail.python.org/mailman/listinfo/python-list
>
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From lutz.horn at posteo.de  Mon Mar 31 08:37:32 2014
From: lutz.horn at posteo.de (Lutz Horn)
Date: Mon, 31 Mar 2014 14:37:32 +0200
Subject: Python IM server
In-Reply-To: <cd39e1e2-6580-47a6-8cc6-d753f4c0200d@googlegroups.com>
References: <cd39e1e2-6580-47a6-8cc6-d753f4c0200d@googlegroups.com>
Message-ID: <d9fcb885e8933137625a3b7086a4914b@posteo.de>

Hi,

>   I want to develop a instant message server, simply has user and 
> group entity.
> 
> Is there any better existing open-source one?

Take a look at XMPP[0]. There are some Python libraries[1].

[0] https://en.wikipedia.org/wiki/XMPP
[1] http://xmpp.org/xmpp-software/libraries/

-- 
Opt out of global data surveillance programs like PRISM, XKeyscore and 
Tempora.
https://prism-break.org


From invalid at invalid.invalid  Mon Mar 31 10:14:39 2014
From: invalid at invalid.invalid (Grant Edwards)
Date: Mon, 31 Mar 2014 14:14:39 +0000 (UTC)
Subject: Explanation of this Python language feature? [x for x in x for
 x in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <j8-dne29t9g2VarOnZ2dnUVZ_qSdnZ2d@giganews.com>
 <5337f57d$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <op.xdj4p4sx5079vu@gnudebeest>
Message-ID: <lhbt8f$9j9$1@reader1.panix.com>

On 2014-03-30, Rhodri James <rhodri at wildebst.org.uk> wrote:
> On Sun, 30 Mar 2014 11:44:13 +0100, Steven D'Aprano  
>
>> Among fans of the British writer Terry Pratchett, the usual term is
>> Merkins. Including among Merkin fans.
>
> Many of whom even know what a merkin is, and use the term anyway.

As much as I'd rather not be called a Merkin, one can't really get mad
at Terry Pratchett fans...

-- 
Grant Edwards               grant.b.edwards        Yow! I'm also against
                                  at               BODY-SURFING!!
                              gmail.com            


From rosuav at gmail.com  Mon Mar 31 10:33:09 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 1 Apr 2014 01:33:09 +1100
Subject: Code style query: multiple assignments in if/elif tree
Message-ID: <CAPTjJmqiyX5HSP+vb+PnyN4zD0_r-PO7SOiurv+WEo-GS6Ax1g@mail.gmail.com>

Call this a code review request, if you like. I'm wondering how you'd
go about coding something like this.

Imagine you're in a train, and the brakes don't apply instantly. The
definition, in the interests of passenger comfort, is that the first
second of brake application has an acceleration of 0.2 m/s/s, the next
second has 0.425 m/s/s, and thereafter full effect of 0.85 m/s/s. You
have a state variable that says whether the brakes have just been
applied, have already been applied for at least two seconds, or
haven't yet been applied at all. Problem: Work out how far you'll go
before the brakes reach full power, and how fast you'll be going at
that point.

Here's how I currently have the code. The variable names are a tad
long, as this was also part of me teaching my brother Python.

# Already got the brakes fully on
if mode=="Brake2": distance_to_full_braking_power, speed_full_brake =
0.0, curspeed
# The brakes went on one second ago, they're nearly full
elif mode=="Brake1": distance_to_full_braking_power, speed_full_brake
= curspeed - 0.2125, curspeed - 0.425
# Brakes aren't on.
else: distance_to_full_braking_power, speed_full_brake = (curspeed -
0.1) + (curspeed - 0.4125), curspeed - 0.625
# If we hit the brakes now (or already have hit them), we'll go
another d meters and be going at s m/s before reaching full braking
power.

But I don't like the layout. I could change it to a single assignment
with expression-if, but that feels awkward too. How would you lay this
out?

(Note that the "else" case could have any of several modes in it, so I
can't so easily use a dict.)

ChrisA


From marko at pacujo.net  Mon Mar 31 11:40:42 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 31 Mar 2014 18:40:42 +0300
Subject: Code style query: multiple assignments in if/elif tree
References: <mailman.8744.1396276875.18130.python-list@python.org>
Message-ID: <874n2ecr5x.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Call this a code review request, if you like. I'm wondering how you'd
> go about coding something like this.

As a simple layout question, I'd do it like this:

========================================================================
if mode == "Brake2":
    # Already got the brakes fully on
    distance_to_full_braking_power = 0.0
    speed_full_brake = curspeed
elif mode == "Brake1":
    # The brakes went on one second ago, they're nearly full
    distance_to_full_braking_power = curspeed - 0.2125
    speed_full_brake = curspeed - 0.425
else:
    # Brakes aren't on.
    distance_to_full_braking_power = (curspeed - 0.1) + (curspeed - 0.4125)
    speed_full_brake = curspeed - 0.625

# If we hit the brakes now (or already have hit them), we'll go another
# d meters and be going at s m/s before reaching full braking power.
========================================================================


Marko


From rosuav at gmail.com  Mon Mar 31 12:03:54 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 1 Apr 2014 03:03:54 +1100
Subject: Code style query: multiple assignments in if/elif tree
In-Reply-To: <874n2ecr5x.fsf@elektro.pacujo.net>
References: <mailman.8744.1396276875.18130.python-list@python.org>
 <874n2ecr5x.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmqTTs4FT_X-bQHTpvnnYNm8ojuFBRGkoTNx62CRBHM4rQ@mail.gmail.com>

On Tue, Apr 1, 2014 at 2:40 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> As a simple layout question, I'd do it like this:
>
> ========================================================================
> if mode == "Brake2":
>     # Already got the brakes fully on
>     distance_to_full_braking_power = 0.0
>     speed_full_brake = curspeed
> elif mode == "Brake1":
>     # The brakes went on one second ago, they're nearly full
>     distance_to_full_braking_power = curspeed - 0.2125
>     speed_full_brake = curspeed - 0.425
> else:
>     # Brakes aren't on.
>     distance_to_full_braking_power = (curspeed - 0.1) + (curspeed - 0.4125)
>     speed_full_brake = curspeed - 0.625
>
> # If we hit the brakes now (or already have hit them), we'll go another
> # d meters and be going at s m/s before reaching full braking power.
> ========================================================================

No particular advantage over the current version - it doesn't simplify
it any, all you've done is break it across more lines.

(The unpacking may not be ideal; as I said, this was a vehicle for
teaching oddments of Python, so I used multiple assignment partly for
the sake of using it.)

Incidentally, if you want to see the code in context, it's here:

https://github.com/Rosuav/runningtime/blob/master/runningtime.py

ChrisA


From rustompmody at gmail.com  Mon Mar 31 12:20:27 2014
From: rustompmody at gmail.com (Rustom Mody)
Date: Mon, 31 Mar 2014 09:20:27 -0700 (PDT)
Subject: Code style query: multiple assignments in if/elif tree
In-Reply-To: <mailman.8745.1396281843.18130.python-list@python.org>
References: <mailman.8744.1396276875.18130.python-list@python.org>
 <874n2ecr5x.fsf@elektro.pacujo.net>
 <mailman.8745.1396281843.18130.python-list@python.org>
Message-ID: <6775d115-a592-4082-a427-5789e1dd2875@googlegroups.com>

On Monday, March 31, 2014 9:33:54 PM UTC+5:30, Chris Angelico wrote:
> On Tue, Apr 1, 2014 at 2:40 AM, Marko Rauhamaa wrote:
> > As a simple layout question, I'd do it like this:
> > ========================================================================
> > if mode == "Brake2":
> >     # Already got the brakes fully on
> >     distance_to_full_braking_power = 0.0
> >     speed_full_brake = curspeed
> > elif mode == "Brake1":
> >     # The brakes went on one second ago, they're nearly full
> >     distance_to_full_braking_power = curspeed - 0.2125
> >     speed_full_brake = curspeed - 0.425
> > else:
> >     # Brakes aren't on.
> >     distance_to_full_braking_power = (curspeed - 0.1) + (curspeed - 0.4125)
> >     speed_full_brake = curspeed - 0.625
> > # If we hit the brakes now (or already have hit them), we'll go another
> > # d meters and be going at s m/s before reaching full braking power.
> > ========================================================================

> No particular advantage over the current version - it doesn't simplify
> it any, all you've done is break it across more lines.

Not answering your original question but the above comment

Your version was sufficiently garbled indentation-wise (it may give you sweet
pleasure to know my 'client' is GG) that I gave up on reading it.

Marko's version was clear enough that it seems to match your spec
[Ive not really verified it word for word... Just sayin']

On the whole I prefer multiple assignments.
Maybe in this case use small variable names with
separate(d) explanatory comments??


From rosuav at gmail.com  Mon Mar 31 12:29:54 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 1 Apr 2014 03:29:54 +1100
Subject: Code style query: multiple assignments in if/elif tree
In-Reply-To: <6775d115-a592-4082-a427-5789e1dd2875@googlegroups.com>
References: <mailman.8744.1396276875.18130.python-list@python.org>
 <874n2ecr5x.fsf@elektro.pacujo.net>
 <mailman.8745.1396281843.18130.python-list@python.org>
 <6775d115-a592-4082-a427-5789e1dd2875@googlegroups.com>
Message-ID: <CAPTjJmquyx7a4w31b2sUdHbzSvaYv=GS6+bGpV6Q9Q-1GnZKyA@mail.gmail.com>

On Tue, Apr 1, 2014 at 3:20 AM, Rustom Mody <rustompmody at gmail.com> wrote:
> On the whole I prefer multiple assignments.
> Maybe in this case use small variable names with
> separate(d) explanatory comments??

Shorter variable names would certainly be the more normal, heh. I let
my brother do that part of the typing, picking names and so on. Better
for teaching to let the victi-- err, the student have the power to
choose. :)

ChrisA


From contact.trigon at gmail.com  Mon Mar 31 13:28:00 2014
From: contact.trigon at gmail.com (Abe)
Date: Mon, 31 Mar 2014 10:28:00 -0700 (PDT)
Subject: checking if two things do not equal None
In-Reply-To: <mailman.8732.1396252624.18130.python-list@python.org>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <mailman.8732.1396252624.18130.python-list@python.org>
Message-ID: <4e22f311-cd65-4d1a-9696-6c00127d67ec@googlegroups.com>

> I couldn't see anyone else give this, but I like
> if None not in (a, b):

I did.

> I am now considering:

> if None not in (a,b):
> or
> if (a is not None) and (b is not None):

However, I decided to just turn the two parameters into one (sequence), since they were logically grouped anyhow.




From ian.g.kelly at gmail.com  Mon Mar 31 13:40:54 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 31 Mar 2014 11:40:54 -0600
Subject: unicode as valid naming symbols
In-Reply-To: <53393BA4.2080305@rece.vub.ac.be>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
 <53393BA4.2080305@rece.vub.ac.be>
Message-ID: <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>

On Mon, Mar 31, 2014 at 3:55 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> On 27-03-14 17:22, Ian Kelly wrote:
>> On Thu, Mar 27, 2014 at 9:28 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>>>> Do you think that the ability to write this would be an improvement?
>>>>
>>>> import ?
>>>> ? = ?.??
>>>> ? = 5*?.??
>>>> ? = ? - 1
>>>> ??? = [?.??**?.?*?{?|?.?} for ? in ?.?]
>>>> ?.??????(???)
>>>
>>>    Steven, you're killing me here; argument by analogy does not work!
>> [  ------ 8< ---------- ]
>> One of the things that Python is widely known for is its readability.
>> Allowing symbols such as ? to denote identifiers may be quite
>> expressive and appreciable to the person writing the code. However it
>> damages readability considerably, as seen in Steven's example above.
>> Personally I'm not interested in having to maintain another
>> programmer's code that arbitrarily uses ? as a timer function, ? as
>> intersection or ? as a matrix constructor.
>
> I don't find Steven's example convincing. Sure it can be used in a way
> that damages readability considerably however lots of things in python
> can be abused in a way that damages readability considerably.
>
> That you are not interested in having to maintain someone's code who
> would use such symbols is irrelevant. IIRC people have used the exact
> same kind of argument against decorators and the if-else operator.
>
> It seems we are all consenting adults until someone doesn't like the
> idea how it might influence his job. In that case it shouldn't be
> allowed.

That was an exaggeration on my part.  It wouldn't affect my job, as I
wouldn't expect to ever actually have to maintain anything like the
above.  My greater point though is that it damages Python's
readability for no actual gain in my view.  There is nothing useful
you can do with a name that is the U+1F4A9 character that you can't do
just as easily with alphanumeric identifiers like pile_of_poo (or
????_??????? if one prefers; that's auto-translated, so don't blame me
if it's a poor translation). The kinds of symbols that we're talking
about here aren't part of any writing systems, and so to incorporate
them in *names* as if they were is an abuse of Unicode.

I don't think the comparisons to decorators and the if-else operator
are apt. First, because while those may degrade readability, they do
so in a constrained way.  A decorator application is just the @ symbol
and an identifier.  The if-else is just three expressions separated by
keywords.  In the case of arbitrary Unicode identifiers, we're talking
about approximately doubling the number of different characters (out
of a continuously growing set) that could be used, many of which are
easily confused with other characters. Of course the potential for
confusion already exists, but that's no justification for aggravating
it.

Second, at least in the case of decorators, while I don't dispute that
they can harm readability, I think that in the majority of cases they
actually help it.  That's because the @ syntax placed before a
function or class clearly denotes that the construct is being
decorated by something.  The alternative to the syntax is to place an
assignment like "f = decorate(f)" *after* the definition, where it is
much less prominent.  That the reader then potentially has to go
figure out what the decorator does is true regardless of whether the @
syntax is used or not.  I'm unable to imagine any case where an
arbitrary Unicode identifier would actually improve readability.

Finally, in my experience the "consenting adults" line is usually used
in the context of program or library design.  I don't believe it's
appropriate when discussing the design of the language itself, which
should be kept as clean as possible.  The logical conclusion of that
would be Lisp-like macros where every user ends up with their own
unique and incompatible version of the language, because we're all
consenting adults here, right?


From python.list at tim.thechases.com  Mon Mar 31 14:02:57 2014
From: python.list at tim.thechases.com (Tim Chase)
Date: Mon, 31 Mar 2014 13:02:57 -0500
Subject: unicode as valid naming symbols
In-Reply-To: <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
 <53393BA4.2080305@rece.vub.ac.be>
 <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
Message-ID: <20140331130257.2c90f07e@bigbox.christie.dr>

On 2014-03-31 11:40, Ian Kelly wrote:
> There is nothing useful
> you can do with a name that is the U+1F4A9 character that you can't
> do just as easily with alphanumeric identifiers like pile_of_poo (or
> ????_??????? if one prefers; that's auto-translated, so don't blame
> me if it's a poor translation).  The kinds of symbols that we're
> talking about here aren't part of any writing systems, and so to
> incorporate them in *names* as if they were is an abuse of Unicode.

It does get more complex though, when you could have things like

 ??? = "\U0001f4a9"

Like you, I don't expect to ever encounter something like this in the
wild, but they are indeed symbols used in a writing system. :-)

-tkc




From ian.g.kelly at gmail.com  Mon Mar 31 14:10:44 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 31 Mar 2014 12:10:44 -0600
Subject: unicode as valid naming symbols
In-Reply-To: <20140331130257.2c90f07e@bigbox.christie.dr>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
 <53393BA4.2080305@rece.vub.ac.be>
 <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
 <20140331130257.2c90f07e@bigbox.christie.dr>
Message-ID: <CALwzidm3YWyyFsX38yecH4PESuapYgv_OeQXFztSNnsiMi1k0Q@mail.gmail.com>

On Mon, Mar 31, 2014 at 12:02 PM, Tim Chase
<python.list at tim.thechases.com> wrote:
> On 2014-03-31 11:40, Ian Kelly wrote:
>> There is nothing useful
>> you can do with a name that is the U+1F4A9 character that you can't
>> do just as easily with alphanumeric identifiers like pile_of_poo (or
>> ????_??????? if one prefers; that's auto-translated, so don't blame
>> me if it's a poor translation).  The kinds of symbols that we're
>> talking about here aren't part of any writing systems, and so to
>> incorporate them in *names* as if they were is an abuse of Unicode.
>
> It does get more complex though, when you could have things like
>
>  ??? = "\U0001f4a9"
>
> Like you, I don't expect to ever encounter something like this in the
> wild, but they are indeed symbols used in a writing system. :-)

That's already a legal identifier, though.  The constituent ideographs
are categorized as "Letter, Other", not symbols.


From moritz.beber at gmail.com  Mon Mar 31 15:22:24 2014
From: moritz.beber at gmail.com (Moritz Emanuel Beber)
Date: Mon, 31 Mar 2014 21:22:24 +0200
Subject: checking if two things do not equal None
In-Reply-To: <4e22f311-cd65-4d1a-9696-6c00127d67ec@googlegroups.com>
References: <0245aca0-c6b7-493a-aa52-2c3ef6462dbd@googlegroups.com>
 <mailman.8732.1396252624.18130.python-list@python.org>
 <4e22f311-cd65-4d1a-9696-6c00127d67ec@googlegroups.com>
Message-ID: <5339C070.3030707@gmail.com>


On 31/03/14 19:28, Abe wrote:
>> I couldn't see anyone else give this, but I like
>> if None not in (a, b):
> I did.
>
>> I am now considering:
>> if None not in (a,b):
>> or
>> if (a is not None) and (b is not None):
That's just

if not (a is None or b is None):

but you seem to have found your way.
> However, I decided to just turn the two parameters into one (sequence), since they were logically grouped anyhow.
>
>



From antoon.pardon at rece.vub.ac.be  Mon Mar 31 15:31:13 2014
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Mon, 31 Mar 2014 21:31:13 +0200
Subject: unicode as valid naming symbols
In-Reply-To: <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
 <53393BA4.2080305@rece.vub.ac.be>
 <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
Message-ID: <5339C281.7080300@rece.vub.ac.be>

Op 31-03-14 19:40, Ian Kelly schreef:
> On Mon, Mar 31, 2014 at 3:55 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> On 27-03-14 17:22, Ian Kelly wrote:
>>> On Thu, Mar 27, 2014 at 9:28 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
>>>>> Do you think that the ability to write this would be an improvement?
>>>>>
>>>>> import ?
>>>>> ? = ?.??
>>>>> ? = 5*?.??
>>>>> ? = ? - 1
>>>>> ??? = [?.??**?.?*?{?|?.?} for ? in ?.?]
>>>>> ?.??????(???)
>>>>
>>>>    Steven, you're killing me here; argument by analogy does not work!
>>> [  ------ 8< ---------- ]
>>> One of the things that Python is widely known for is its readability.
>>> Allowing symbols such as ? to denote identifiers may be quite
>>> expressive and appreciable to the person writing the code. However it
>>> damages readability considerably, as seen in Steven's example above.
>>> Personally I'm not interested in having to maintain another
>>> programmer's code that arbitrarily uses ? as a timer function, ? as
>>> intersection or ? as a matrix constructor.
>>
>> I don't find Steven's example convincing. Sure it can be used in a way
>> that damages readability considerably however lots of things in python
>> can be abused in a way that damages readability considerably.
>>
>> That you are not interested in having to maintain someone's code who
>> would use such symbols is irrelevant. IIRC people have used the exact
>> same kind of argument against decorators and the if-else operator.
>>
>> It seems we are all consenting adults until someone doesn't like the
>> idea how it might influence his job. In that case it shouldn't be
>> allowed.
> 
> That was an exaggeration on my part.  It wouldn't affect my job, as I
> wouldn't expect to ever actually have to maintain anything like the
> above.  My greater point though is that it damages Python's
> readability for no actual gain in my view.  There is nothing useful
> you can do with a name that is the U+1F4A9 character that you can't do
> just as easily with alphanumeric identifiers like pile_of_poo (or
> ????_??????? if one prefers; that's auto-translated, so don't blame me
> if it's a poor translation). The kinds of symbols that we're talking
> about here aren't part of any writing systems, and so to incorporate
> them in *names* as if they were is an abuse of Unicode.

Your argument doesn't has much weight. First of all it can be used
for just restricting names to the ascii range. Second of all I
think a good chosen symbolic name can be more readable than a
name in a character set you are not familiar with. A good chosen
symbol will evoke a meaning with a lot of people. A name in a
character set you are not familiar with is just gibberish to
you.

> I don't think the comparisons to decorators and the if-else operator
> are apt.

I didn't make such a comparison. I just noted the arguments against
were similar.

> First, because while those may degrade readability, they do
> so in a constrained way.  A decorator application is just the @ symbol
> and an identifier.

And if abused, can totally change the working of your function. There
is no guarantee that the function returned, has any relation with the
original function. If that can't be a night mare for readability,
I don't know what is.

> The if-else is just three expressions separated by
> keywords.

Yes but if used unrestrained in arbitrary expressions will make those
expressions hard to understand.

> In the case of arbitrary Unicode identifiers, we're talking
> about approximately doubling the number of different characters (out
> of a continuously growing set) that could be used, many of which are
> easily confused with other characters. Of course the potential for
> confusion already exists, but that's no justification for aggravating
> it.

So what if we double the number of different characters? I don't care
about the number of them, I care about how meaningful they are. And
as you say confusion is already possible. A good programmer knows
how to deal with such a possible confusion, that the number of
cases increases, doesn't need to be a problem for those that care
about this.

> Second, at least in the case of decorators, while I don't dispute that
> they can harm readability, I think that in the majority of cases they
> actually help it.

But that is not a fair comparison now, is it. What you are doing here
is comparing actual use, to a worst case doom scenario.

-- 
Antoon Pardon


From tjreedy at udel.edu  Mon Mar 31 16:12:08 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 31 Mar 2014 16:12:08 -0400
Subject: unicode as valid naming symbols
In-Reply-To: <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
 <53393BA4.2080305@rece.vub.ac.be>
 <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
Message-ID: <lhci6r$h9t$1@ger.gmane.org>

On 3/31/2014 1:40 PM, Ian Kelly wrote:

> Second, at least in the case of decorators, while I don't dispute that
> they can harm readability, I think that in the majority of cases they
> actually help it.  That's because the @ syntax placed before a
> function or class clearly denotes that the construct is being
> decorated by something.  The alternative to the syntax is to place an
> assignment like "f = decorate(f)" *after* the definition, where it is
> much less prominent.

Plus, it means writing and reading the name 3 times instead  of 1. This 
is not much of an issue for 'f', but it is for names like 
'modify_x07_with_qz46pt'. Names like this occur when interfacing to 
external systems that dictate the names needed (as when interfacing 
Python to Objective-C  on Macs).

-- 
Terry Jan Reedy



From sturla.molden at gmail.com  Mon Mar 31 16:16:16 2014
From: sturla.molden at gmail.com (Sturla Molden)
Date: Mon, 31 Mar 2014 20:16:16 +0000 (UTC)
Subject: Examples of modern GUI python programms
References: <db2ed73f-aa1f-42d6-abcd-0b7c29c95e1f@googlegroups.com>
Message-ID: <140398123417988155.262097sturla.molden-gmail.com@news.gmane.org>

Metallicow <metaliobovinus at gmail.com> wrote:

> One would have to tool through the PySide agreement for their specifics,
> but as I recall it is exactly the same as Qt is, which makes sense. 

According to their web page, PySide is only LGPL. Qt is LGPL or commercial.


> Just because a library is LGPL doesn't mean the authors code has to be
> depending on the circumstances. That just means usually you have to be
> able to provide the library code(and your mods to it) used.

No, that would be MPL (Mozilla Public License). Many believe LGPL implies
the same freedom as MPL. It does not.

LGPL also means you also have to give the user a means to "relink the
program with a different version of the library". That is a less known
restriction of LGPL. Usually this is done by providing the LGPL library as
a DLL. But a DLL is actually not sufficient, in case a different version of
the library breaks the application binary interface (ABI). In case of ABI
breakage, LGPL means the user be given access to the program source code to
recompile and relink the program. 

Because of the closed nature of app bundles on iOS, the user cannot do
anything with an .so or .dylib file. Thus, the DLL solution to LGPL
infestation is not possible on iOS, even if it were sufficient.

MPL is basically a version og LGPL that has removed the requirement to make
relinkage possible. That is e.g. why a library like Eigen is released as
MPL instead of LGPL.


Sturla



From tjreedy at udel.edu  Mon Mar 31 16:15:16 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 31 Mar 2014 16:15:16 -0400
Subject: unicode as valid naming symbols
In-Reply-To: <5339C281.7080300@rece.vub.ac.be>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
 <53393BA4.2080305@rece.vub.ac.be>
 <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
 <5339C281.7080300@rece.vub.ac.be>
Message-ID: <lhcicm$j9u$1@ger.gmane.org>

On 3/31/2014 3:31 PM, Antoon Pardon wrote:
> Op 31-03-14 19:40, Ian Kelly schreef:

>> First, because while those may degrade readability, they do
>> so in a constrained way.  A decorator application is just the @ symbol
>> and an identifier.
>
> And if abused, can totally change the working of your function. There
> is no guarantee that the function returned, has any relation with the
> original function. If that can't be a night mare for readability,
> I don't know what is.

This is a matter of the wrapping function, not the decorator syntax 
abbreviation.

@twist_the_function_meaning
def f: return clear_expression

is no worse in this regard than the written out form

def f: return clear_expression
f = twist_the_function_meaning(f)

-- 
Terry Jan Reedy



From rhodri at wildebst.org.uk  Mon Mar 31 16:31:59 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Mon, 31 Mar 2014 21:31:59 +0100
Subject: Code style query: multiple assignments in if/elif tree
References: <mailman.8744.1396276875.18130.python-list@python.org>
 <874n2ecr5x.fsf@elektro.pacujo.net>
 <mailman.8745.1396281843.18130.python-list@python.org>
 <6775d115-a592-4082-a427-5789e1dd2875@googlegroups.com>
 <mailman.8746.1396283403.18130.python-list@python.org>
Message-ID: <op.xdlsnlqv5079vu@gnudebeest>

On Mon, 31 Mar 2014 17:29:54 +0100, Chris Angelico <rosuav at gmail.com>  
wrote:

> On Tue, Apr 1, 2014 at 3:20 AM, Rustom Mody <rustompmody at gmail.com>  
> wrote:
>> On the whole I prefer multiple assignments.
>> Maybe in this case use small variable names with
>> separate(d) explanatory comments??
>
> Shorter variable names would certainly be the more normal, heh. I let
> my brother do that part of the typing, picking names and so on. Better
> for teaching to let the victi-- err, the student have the power to
> choose. :)

Not just more normal, but more readable too.  The trouble with your  
original example was that the lines were too long (even ignoring the  
trouble line-wrapping caused in your post) to take in with only a couple  
of eye movements along the line.  That makes a really quite surprising  
difference to the comprehensibility of the whole thing.


-- 
Rhodri James *-* Wildebeest Herder to the Masses


From marko at pacujo.net  Mon Mar 31 16:34:41 2014
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 31 Mar 2014 23:34:41 +0300
Subject: unicode as valid naming symbols
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
 <53393BA4.2080305@rece.vub.ac.be>
 <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
 <5339C281.7080300@rece.vub.ac.be>
 <mailman.8754.1396297207.18130.python-list@python.org>
Message-ID: <871txiayzi.fsf@elektro.pacujo.net>

Terry Reedy <tjreedy at udel.edu>:

> @twist_the_function_meaning
> def f: return clear_expression
>
> is no worse in this regard than the written out form
>
> def f: return clear_expression
> f = twist_the_function_meaning(f)

I don't remember feeling the need for either.

I have written wrappers of all sorts, but somehow that pattern just
feels alien to me so far.


Marko


From rhodri at wildebst.org.uk  Mon Mar 31 16:46:21 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Mon, 31 Mar 2014 21:46:21 +0100
Subject: Explanation of this Python language feature? [x for x in x for x
 in x] (to flatten a nested list)
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgoh7j$otg$1@speranza.aioe.org>
 <mailman.8440.1395651801.18130.python-list@python.org>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <533836c4$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhb0on$pcj$1@speranza.aioe.org>
Message-ID: <op.xdltbjr05079vu@gnudebeest>

On Mon, 31 Mar 2014 07:08:24 +0100, Mark H Harris <harrismh777 at gmail.com>  
wrote:

> On 3/30/14 10:22 AM, Steven D'Aprano wrote:
>> In 1991, there was no wireless, no mobile computing, hardly any public
>> Internet outside of the universities. It was before the Eternal
>> September, and only a few years after the Great Renaming.
>
>    I was using arpanet since the late 1970s.

I was using JANet since the early 80s, and I'm by no means the oldest
person here.  I should stop playing that card if I were you.

>>>  I didn't really start using unicode
>>> until about 5 years ago; python has only really used it since python3.
>>> right?
>>  No. Python 2.2 introduced Unicode.
>  I didn't ask when it was introduced, I asked when it became useful?

No you didn't.  You even quoted yourself as not saying it, just in
case you weren't clear about that.

And since you're so experienced, you should recognise this sound:

*plonk*

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From rhodri at wildebst.org.uk  Mon Mar 31 16:47:15 2014
From: rhodri at wildebst.org.uk (Rhodri James)
Date: Mon, 31 Mar 2014 21:47:15 +0100
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhau51$jtt$1@speranza.aioe.org>
Message-ID: <op.xdltc1f15079vu@gnudebeest>

On Mon, 31 Mar 2014 06:23:46 +0100, Mark H Harris <harrismh777 at gmail.com>  
wrote:

> The main point of the link is the status on English as an official  
> language.  28 out of 50 states have legislated English as the official  
> language; meaning, that you either speak and write English, or you're  
> going to have a really tough time participating in culture, business,  
> government, and recreation.

That few?  I'm surprised.  Presumably the other states don't have any  
contention for the status of "official language"?

I'm also surprised that you aren't surprised that over half the states  
feel the need to specify an official language.  One might wonder why...

-- 
Rhodri James *-* Wildebeest Herder to the Masses


From ned at nedbatchelder.com  Mon Mar 31 17:42:33 2014
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Mon, 31 Mar 2014 17:42:33 -0400
Subject: Code style query: multiple assignments in if/elif tree
In-Reply-To: <CAPTjJmqTTs4FT_X-bQHTpvnnYNm8ojuFBRGkoTNx62CRBHM4rQ@mail.gmail.com>
References: <mailman.8744.1396276875.18130.python-list@python.org>
 <874n2ecr5x.fsf@elektro.pacujo.net>
 <CAPTjJmqTTs4FT_X-bQHTpvnnYNm8ojuFBRGkoTNx62CRBHM4rQ@mail.gmail.com>
Message-ID: <lhcnga$dd5$1@ger.gmane.org>

On 3/31/14 12:03 PM, Chris Angelico wrote:
> Incidentally, if you want to see the code in context, it's here:
>
> https://github.com/Rosuav/runningtime/blob/master/runningtime.py
>
> ChrisA

I know you didn't ask about these aspects, but they jumped out at me: 
tabs for indentation instead of spaces, and docstring-style comments in 
places that aren't docstrings.  These seem like unusual choices.

-- 
Ned Batchelder, http://nedbatchelder.com



From tjreedy at udel.edu  Mon Mar 31 18:06:37 2014
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 31 Mar 2014 18:06:37 -0400
Subject: OFF TOPIC Spanish in the USA [was Re: Explanation of this Python
 language feature?]
In-Reply-To: <op.xdltc1f15079vu@gnudebeest>
References: <9daf0806-02de-4447-964c-c8f8953c23e5@googlegroups.com>
 <lgq8th$nj4$1@speranza.aioe.org> <87ior3w740.fsf@elektro.pacujo.net>
 <lgqgn7$bpd$1@speranza.aioe.org>
 <mailman.8478.1395710470.18130.python-list@python.org>
 <lgqq99$v5j$1@speranza.aioe.org> <lgtsga$2ei$1@dont-email.me>
 <lh1h1f$ov3$1@speranza.aioe.org>
 <5334c38e$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh4ouu$n8l$1@speranza.aioe.org>
 <53364327$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh5iqs$j0m$1@speranza.aioe.org>
 <mailman.8683.1396069736.18130.python-list@python.org>
 <53365F55.2040302@gmail.com>
 <mailman.8688.1396073027.18130.python-list@python.org>
 <lh5vq3$c1j$1@speranza.aioe.org>
 <mailman.8690.1396107966.18130.python-list@python.org>
 <lh8bej$n7b$1@speranza.aioe.org>
 <5337ba48$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lhau51$jtt$1@speranza.aioe.org> <op.xdltc1f15079vu@gnudebeest>
Message-ID: <lhcotg$vih$1@ger.gmane.org>

On 3/31/2014 4:47 PM, Rhodri James wrote:
> On Mon, 31 Mar 2014 06:23:46 +0100, Mark H Harris
> <harrismh777 at gmail.com> wrote:
>
>> The main point of the link is the status on English as an official
>> language.  28 out of 50 states have legislated English as the official
>> language; meaning, that you either speak and write English, or you're
>> going to have a really tough time participating in culture, business,
>> government, and recreation.

Perhaps the link was
https://en.wikipedia.org/wiki/Languages_of_the_United_States#Official_language_status

> That few?  I'm surprised.  Presumably the other states don't have any
> contention for the status of "official language"?

The modern 'English primary' movement, with its first state success in 
1981, was a reaction to the 'Spanish co-equal' movement of the 1970s. 
Without state-by-state data on the push for legislation, I see no clear 
pattern in the list of which states have such a law.


-- 
Terry Jan Reedy



From rosuav at gmail.com  Mon Mar 31 18:50:36 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 1 Apr 2014 09:50:36 +1100
Subject: Code style query: multiple assignments in if/elif tree
In-Reply-To: <lhcnga$dd5$1@ger.gmane.org>
References: <mailman.8744.1396276875.18130.python-list@python.org>
 <874n2ecr5x.fsf@elektro.pacujo.net>
 <CAPTjJmqTTs4FT_X-bQHTpvnnYNm8ojuFBRGkoTNx62CRBHM4rQ@mail.gmail.com>
 <lhcnga$dd5$1@ger.gmane.org>
Message-ID: <CAPTjJmrm9+49hvsk41ijhsOiZgCEumjD=g9HgxkutK3Of8YkRw@mail.gmail.com>

On Tue, Apr 1, 2014 at 8:42 AM, Ned Batchelder <ned at nedbatchelder.com> wrote:
> On 3/31/14 12:03 PM, Chris Angelico wrote:
>>
>> Incidentally, if you want to see the code in context, it's here:
>>
>> https://github.com/Rosuav/runningtime/blob/master/runningtime.py
>>
>> ChrisA
>
>
> I know you didn't ask about these aspects, but they jumped out at me: tabs
> for indentation instead of spaces, and docstring-style comments in places
> that aren't docstrings.  These seem like unusual choices.

Tabs instead of spaces? They're plenty common enough, but I am *not*
getting into that debate now. The file's perfectly consistent - aside
from inside strings, all indentation is done with tabs, one per level.

How do you go about doing multi-line comments? I know I've seen other
code using triple-quoted strings for long comments before.

ChrisA


From ben+python at benfinney.id.au  Mon Mar 31 18:57:31 2014
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 01 Apr 2014 09:57:31 +1100
Subject: Code style query: multiple assignments in if/elif tree
References: <mailman.8744.1396276875.18130.python-list@python.org>
 <874n2ecr5x.fsf@elektro.pacujo.net>
 <CAPTjJmqTTs4FT_X-bQHTpvnnYNm8ojuFBRGkoTNx62CRBHM4rQ@mail.gmail.com>
 <lhcnga$dd5$1@ger.gmane.org>
 <CAPTjJmrm9+49hvsk41ijhsOiZgCEumjD=g9HgxkutK3Of8YkRw@mail.gmail.com>
Message-ID: <85y4zqkmck.fsf@benfinney.id.au>

Chris Angelico <rosuav at gmail.com> writes:

> How do you go about doing multi-line comments? I know I've seen other
> code using triple-quoted strings for long comments before.

Just use a sequence of one-line comments::

    # Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut a
    # sapien tempor, suscipit orci sed, elementum nisl. Suspendisse at
    # lacus ut diam dignissim lobortis ac vitae augue.
    #
    # Phasellus bibendum neque a justo vulputate, quis accumsan quam
    # egestas. Etiam aliquet blandit ante sit amet cursus.

A decent code editor (e.g. Emacs, Vim) will allow manipulation of
a sequence of one-line comments in Python's comment style, and allow
treating it as a paragraphs for purposes such as re-wrapping the lines.

I agree with others that triple-quoted strings are best reserved for
string literals (including docstrings), not comments.

-- 
 \         ?Alternative explanations are always welcome in science, if |
  `\   they are better and explain more. Alternative explanations that |
_o__) explain nothing are not welcome.? ?Victor J. Stenger, 2001-11-05 |
Ben Finney



From rosuav at gmail.com  Mon Mar 31 19:12:38 2014
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 1 Apr 2014 10:12:38 +1100
Subject: Code style query: multiple assignments in if/elif tree
In-Reply-To: <85y4zqkmck.fsf@benfinney.id.au>
References: <mailman.8744.1396276875.18130.python-list@python.org>
 <874n2ecr5x.fsf@elektro.pacujo.net>
 <CAPTjJmqTTs4FT_X-bQHTpvnnYNm8ojuFBRGkoTNx62CRBHM4rQ@mail.gmail.com>
 <lhcnga$dd5$1@ger.gmane.org>
 <CAPTjJmrm9+49hvsk41ijhsOiZgCEumjD=g9HgxkutK3Of8YkRw@mail.gmail.com>
 <85y4zqkmck.fsf@benfinney.id.au>
Message-ID: <CAPTjJmrBk9bnAdA_N_OtCqwJSa1fhRxD3-sCVLQTQzwjP4mM2w@mail.gmail.com>

On Tue, Apr 1, 2014 at 9:57 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> Chris Angelico <rosuav at gmail.com> writes:
>
>> How do you go about doing multi-line comments? I know I've seen other
>> code using triple-quoted strings for long comments before.
>
> Just use a sequence of one-line comments::
>
>     # Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut a
>     # sapien tempor, suscipit orci sed, elementum nisl. Suspendisse at
>     # lacus ut diam dignissim lobortis ac vitae augue.
>     #
>     # Phasellus bibendum neque a justo vulputate, quis accumsan quam
>     # egestas. Etiam aliquet blandit ante sit amet cursus.
>
> A decent code editor (e.g. Emacs, Vim) will allow manipulation of
> a sequence of one-line comments in Python's comment style, and allow
> treating it as a paragraphs for purposes such as re-wrapping the lines.
>
> I agree with others that triple-quoted strings are best reserved for
> string literals (including docstrings), not comments.

Fair enough. I can't remember where (or when!) it was that I learned
triple-quoted strings were appropriately abused as comments, so I've
just done a quick re-layout into hash comments.

ChrisA


From sturla.molden at gmail.com  Mon Mar 31 20:44:33 2014
From: sturla.molden at gmail.com (Sturla Molden)
Date: Tue, 1 Apr 2014 00:44:33 +0000 (UTC)
Subject: Line of best fit
References: <0fb15100-15e8-46d6-a38f-b187c7012e62@googlegroups.com>
 <roy-157E04.08214831032014@news.panix.com>
Message-ID: <1359723961418005824.044550sturla.molden-gmail.com@news.gmane.org>

Roy Smith <roy at panix.com> wrote:

> Please tell us more about the environment you're working in.  I'm 
> guessing from the fact that you're calling plt.plot(), that you've 
> already got some add-on modules loaded.  Pandas, maybe?

Probably matplotlib.pyplot



From ian.g.kelly at gmail.com  Mon Mar 31 20:47:48 2014
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 31 Mar 2014 18:47:48 -0600
Subject: unicode as valid naming symbols
In-Reply-To: <5339C281.7080300@rece.vub.ac.be>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
 <53393BA4.2080305@rece.vub.ac.be>
 <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
 <5339C281.7080300@rece.vub.ac.be>
Message-ID: <CALwzidkTRYbpeBCY7gxSXa=ZNimaAe69mGbT0d9sbehHfHgvOw@mail.gmail.com>

On Mon, Mar 31, 2014 at 1:31 PM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> Op 31-03-14 19:40, Ian Kelly schreef:
>> That was an exaggeration on my part.  It wouldn't affect my job, as I
>> wouldn't expect to ever actually have to maintain anything like the
>> above.  My greater point though is that it damages Python's
>> readability for no actual gain in my view.  There is nothing useful
>> you can do with a name that is the U+1F4A9 character that you can't do
>> just as easily with alphanumeric identifiers like pile_of_poo (or
>> ????_??????? if one prefers; that's auto-translated, so don't blame me
>> if it's a poor translation). The kinds of symbols that we're talking
>> about here aren't part of any writing systems, and so to incorporate
>> them in *names* as if they were is an abuse of Unicode.
>
> Your argument doesn't has much weight. First of all it can be used
> for just restricting names to the ascii range.

I disagree.  Non-ASCII written names are useful to anybody who prefers
not to do all their programming in English.

> Second of all I
> think a good chosen symbolic name can be more readable than a
> name in a character set you are not familiar with. A good chosen
> symbol will evoke a meaning with a lot of people. A name in a
> character set you are not familiar with is just gibberish to
> you.

Well, this is the path taken by APL.  It has its supporters.  It's not
known for being readable.

>> I don't think the comparisons to decorators and the if-else operator
>> are apt.
>
> I didn't make such a comparison. I just noted the arguments against
> were similar.

That's the comparison to which I was referring.

>> First, because while those may degrade readability, they do
>> so in a constrained way.  A decorator application is just the @ symbol
>> and an identifier.
>
> And if abused, can totally change the working of your function. There
> is no guarantee that the function returned, has any relation with the
> original function. If that can't be a night mare for readability,
> I don't know what is.

As Terry Reedy noted, this has nothing to do with the decorator
syntax, so it isn't much of an argument against having such syntax.

>> The if-else is just three expressions separated by
>> keywords.
>
> Yes but if used unrestrained in arbitrary expressions will make those
> expressions hard to understand.

I don't disagree.  I hardly ever use it myself, certainly only if it
can fit comfortably into one line, which is rare.  But it's still
quite limited in syntactic scope.

>> In the case of arbitrary Unicode identifiers, we're talking
>> about approximately doubling the number of different characters (out
>> of a continuously growing set) that could be used, many of which are
>> easily confused with other characters. Of course the potential for
>> confusion already exists, but that's no justification for aggravating
>> it.
>
> So what if we double the number of different characters? I don't care
> about the number of them, I care about how meaningful they are. And
> as you say confusion is already possible. A good programmer knows
> how to deal with such a possible confusion, that the number of
> cases increases, doesn't need to be a problem for those that care
> about this.

So tell me then, how would you deal with it?  In the case of script
identifiers, it's often not hard to discern from context whether a
particular character is e.g. a Latin h or a Cyrillic ?.  Assuming the
original author wasn't being intentionally obfuscatory, if the rest of
the identifier is Cyrillic then the character is probably also
Cyrillic.  If it's a one-character identifier, then hopefully the rest
of the module is consistent and you can guess from that.  If the
identifier in question is just one symbol though, then you have a lot
less context.

>
>> Second, at least in the case of decorators, while I don't dispute that
>> they can harm readability, I think that in the majority of cases they
>> actually help it.
>
> But that is not a fair comparison now, is it. What you are doing here
> is comparing actual use, to a worst case doom scenario.

I contend that there is no scenario with arbitrary Unicode identifiers
where readability is improved.


From ethan at stoneleaf.us  Mon Mar 31 20:30:35 2014
From: ethan at stoneleaf.us (Ethan Furman)
Date: Mon, 31 Mar 2014 17:30:35 -0700
Subject: Code style query: multiple assignments in if/elif tree
In-Reply-To: <CAPTjJmrBk9bnAdA_N_OtCqwJSa1fhRxD3-sCVLQTQzwjP4mM2w@mail.gmail.com>
References: <mailman.8744.1396276875.18130.python-list@python.org>
 <874n2ecr5x.fsf@elektro.pacujo.net>
 <CAPTjJmqTTs4FT_X-bQHTpvnnYNm8ojuFBRGkoTNx62CRBHM4rQ@mail.gmail.com>
 <lhcnga$dd5$1@ger.gmane.org>
 <CAPTjJmrm9+49hvsk41ijhsOiZgCEumjD=g9HgxkutK3Of8YkRw@mail.gmail.com>
 <85y4zqkmck.fsf@benfinney.id.au>
 <CAPTjJmrBk9bnAdA_N_OtCqwJSa1fhRxD3-sCVLQTQzwjP4mM2w@mail.gmail.com>
Message-ID: <533A08AB.8060208@stoneleaf.us>

On 03/31/2014 04:12 PM, Chris Angelico wrote:
> On Tue, Apr 1, 2014 at 9:57 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
>> Chris Angelico <rosuav at gmail.com> writes:
>>
>>> How do you go about doing multi-line comments? I know I've seen other
>>> code using triple-quoted strings for long comments before.
>>
>> Just use a sequence of one-line comments::
>>
>>      # Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut a
>>      # sapien tempor, suscipit orci sed, elementum nisl. Suspendisse at
>>      # lacus ut diam dignissim lobortis ac vitae augue.
>>      #
>>      # Phasellus bibendum neque a justo vulputate, quis accumsan quam
>>      # egestas. Etiam aliquet blandit ante sit amet cursus.
>>
>> A decent code editor (e.g. Emacs, Vim) will allow manipulation of
>> a sequence of one-line comments in Python's comment style, and allow
>> treating it as a paragraphs for purposes such as re-wrapping the lines.
>>
>> I agree with others that triple-quoted strings are best reserved for
>> string literals (including docstrings), not comments.
>
> Fair enough. I can't remember where (or when!) it was that I learned
> triple-quoted strings were appropriately abused as comments, so I've
> just done a quick re-layout into hash comments.

Personally, I use the sequence of one-line comments.

But, hey, Guido [1] himself likes the triple-quoted string as comment feature [2], so feel free to use it yourself if 
you like.

--
~Ethan~

[1] https://mail.python.org/pipermail/python-dev/2013-March/124947.html
[2] https://mail.python.org/pipermail/python-ideas/2009-October/006204.html


From steve+comp.lang.python at pearwood.info  Mon Mar 31 20:57:01 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 01 Apr 2014 00:57:01 GMT
Subject: Code style query: multiple assignments in if/elif tree
References: <mailman.8744.1396276875.18130.python-list@python.org>
 <874n2ecr5x.fsf@elektro.pacujo.net>
 <CAPTjJmqTTs4FT_X-bQHTpvnnYNm8ojuFBRGkoTNx62CRBHM4rQ@mail.gmail.com>
 <lhcnga$dd5$1@ger.gmane.org>
 <CAPTjJmrm9+49hvsk41ijhsOiZgCEumjD=g9HgxkutK3Of8YkRw@mail.gmail.com>
 <85y4zqkmck.fsf@benfinney.id.au>
 <mailman.8759.1396307562.18130.python-list@python.org>
Message-ID: <533a0edd$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Tue, 01 Apr 2014 10:12:38 +1100, Chris Angelico wrote:
[...]
>> I agree with others that triple-quoted strings are best reserved for
>> string literals (including docstrings), not comments.
> 
> Fair enough. I can't remember where (or when!) it was that I learned
> triple-quoted strings were appropriately abused as comments, so I've
> just done a quick re-layout into hash comments.

Probably here :-)

But note the emphasis on "abused". The only time I would use triple-
quoted strings as comments is if I wanted to quickly comment out a 
section of code:

do_this()
do_that()
'''
def do_something_else():
    """Docstring"""
    pass
do_something_else()
'''
do_more()
do_less()


sort of thing. (Note the cunning use of ''' instead of """.) But I 
wouldn't leave it like that in production code.

It's *tempting* to use """ to mark out a large block of text, and I 
wouldn't say that doing so was wrong, but it's a bit different, and 
programmers are very like cats: they don't like different.


-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From steve+comp.lang.python at pearwood.info  Mon Mar 31 21:00:52 2014
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: 01 Apr 2014 01:00:52 GMT
Subject: Line of best fit
References: <0fb15100-15e8-46d6-a38f-b187c7012e62@googlegroups.com>
Message-ID: <533a0fc3$0$29994$c3e8da3$5496439d@news.astraweb.com>

On Mon, 31 Mar 2014 04:29:15 -0700, Jamie Mitchell wrote:

> I am new to python so apologies for the ignorance with this question.
> 
> How would I apply a line of best fit to a plot?

That depends on what software you are using to generate the plot. I see 
you have this line of code:

> plt.plot(hs1,hs2,'.')

but you haven't told us what plt is, where it comes from, or anything 
needed for us to answer your question.

So, start by telling us what plt is, and we may be able to tell you 
whether or not it supports lines of best fit.




-- 
Steven D'Aprano
http://import-that.dreamwidth.org/


From nispray at gmail.com  Mon Mar 31 22:38:12 2014
From: nispray at gmail.com (Wesley)
Date: Mon, 31 Mar 2014 19:38:12 -0700 (PDT)
Subject: Python IM server
In-Reply-To: <mailman.8743.1396272420.18130.python-list@python.org>
References: <cd39e1e2-6580-47a6-8cc6-d753f4c0200d@googlegroups.com>
 <mailman.8743.1396272420.18130.python-list@python.org>
Message-ID: <5956f54e-4db3-4fcb-b0b1-c81651392fc2@googlegroups.com>

? 2014?3?31????UTC+8??8?37?32??Lutz Horn???
> Hi,
> 
> 
> 
> >   I want to develop a instant message server, simply has user and 
> 
> > group entity.
> 
> > 
> 
> > Is there any better existing open-source one?
> 
> 
> 
> Take a look at XMPP[0]. There are some Python libraries[1].
> 
> 
> 
> [0] https://en.wikipedia.org/wiki/XMPP
> 
> [1] http://xmpp.org/xmpp-software/libraries/
> 
> 
> 
> -- 
> 
> Opt out of global data surveillance programs like PRISM, XKeyscore and 
> 
> Tempora.
> 
> https://prism-break.org

I am looking at telepathy, empathy.
Currently instant message is urgent, but needs voice/video call in the future.

For instant message, I have user-to-user and user-to-group cases. 
Don't know if it suits well.


From metaliobovinus at gmail.com  Mon Mar 31 23:47:46 2014
From: metaliobovinus at gmail.com (Metallicow)
Date: Mon, 31 Mar 2014 20:47:46 -0700 (PDT)
Subject: Examples of modern GUI python programms
In-Reply-To: <mailman.8753.1396296992.18130.python-list@python.org>
References: <db2ed73f-aa1f-42d6-abcd-0b7c29c95e1f@googlegroups.com>
 <mailman.8753.1396296992.18130.python-list@python.org>
Message-ID: <7731beae-7309-4fbc-b706-d4dd4983f535@googlegroups.com>

On Monday, March 31, 2014 3:16:16 PM UTC-5, Sturla Molden wrote:
> 
> According to their web page, PySide is only LGPL. Qt is LGPL or commercial.


"""
Licensing

PySide has been published as a response to the lack of suitably licensed Qt bindings for Python. PySide is licensed under the LGPL version 2.1 license, allowing both Free/Open source software and proprietary software development.
"""

Read the legal definition of/and proprietary, then go consult a lawyer. That is caught as an exception/addition to the LGPL in the wording.
I don't think anyone pressing the issue would get very far at all, unless there is a real good reason your own non-library source should be disclosed. Are there any legal precedents yet?.... If you didn't pay for it, or don't have a class action suit, or is of national security, then good luck. 

So, yes, PySide is acceptable also in certain situations you don't have to disclose own source. May need to consult with Qt personally on the matter if a Qt license is actually needed for your particular project, but in plain legal wording of the LGPL/Qts/PySides agreements, no, it is not but there are a few rules that have been layed out you will need to follow if you don't have a Qt license.

Anywho, here is some infos detailing a bit more commonly asked situations on their forums regarding PySide.
http://qt-project.org/wiki/About-PySide
http://qt-project.org/forums/viewthread/34770

If you do have a Qt license, then the rules change a bit more in your favor at levels of what you can ignore, that others can't legally.
A couple of our team members has a license to cover the stuff we do, so I don't worry about it much. The majority of it is open anyway, but pity those who expect everything for free. *I can hear it now* boo hoo pdf format is finally "free and open" after all these years of adobe's money*grubbin*making. geez...
Lesson is: Any software/hardware dev should be familiar with the licensing terms of the toolkits they intend to use. There are always hoops to jump through for "Free-Types". Everyone needs to eat also, because as of this writing "Money" has yet to be abolished in this needy world of ours. And also it seems to fuel development in certain cases also.


I often find the writings on the GPL pages about stuff related similarly to sound like a Richard being a crybaby at times, even tho I do respect him for his views he tries to emboss on everyone to create a "not-exactly-freeier-but-just-more-open" overall software society. If everyone had a flat wallet, then this idea would work out nicely.
If I ever write a printer driver, I will make sure I license it GPL and personally send him a copy to inspect, believe me. Maybe when the next raspberry pi revision comes out he'll send 1000's of them out for free also to his supporters and developers also, but I somehow doubt it.
http://www.gnu.org/philosophy/proprietary.html

Anyhow, this should hopefully be enough infos for the OP to get a general idea of what toolkit would be needed for whatever project is in mind. 
As I say ",If not satisfied, contact sales. They are always reassuring to sound the least."


From dwightdhutto at gmail.com  Mon Mar 31 23:58:40 2014
From: dwightdhutto at gmail.com (David Hutto)
Date: Mon, 31 Mar 2014 23:58:40 -0400
Subject: unicode as valid naming symbols
In-Reply-To: <CALwzidkTRYbpeBCY7gxSXa=ZNimaAe69mGbT0d9sbehHfHgvOw@mail.gmail.com>
References: <lgsi07$k1p$1@speranza.aioe.org>
 <mailman.8531.1395775491.18130.python-list@python.org>
 <5331D902.3030902@gmail.com>
 <53321819$0$29994$c3e8da3$5496439d@news.astraweb.com>
 <lh1g3h$meg$1@speranza.aioe.org>
 <CALwzidk+4diadosJ0bDFTj-OjU9ib712iPMBVxvqZfxAsY2cJg@mail.gmail.com>
 <53393BA4.2080305@rece.vub.ac.be>
 <CALwzidkWc+jQtyN7-nFd4wZCryqLNfNc2okVL_kSbCBkE6nuQQ@mail.gmail.com>
 <5339C281.7080300@rece.vub.ac.be>
 <CALwzidkTRYbpeBCY7gxSXa=ZNimaAe69mGbT0d9sbehHfHgvOw@mail.gmail.com>
Message-ID: <CA+vVgJVbh75f9jUm-bg0v4VCopvx_Q3pGnVzVKdqnM-ZXkcRZA@mail.gmail.com>

I personally believe that it becomes hard to have even a programming
language overcome cultural learning styles, and programmatic differences,
because of nurture vs nature.

We can all program something which results in a similar return value, but
overcoming the nurturing the internet provides, becomes an imperative.

I'll just offer a reference to avoid personal mistakes in explaining
something that relates to how programmers/computer scientists/electrical
engineers approach their end results, and why those end results may still
differ in the mentality of the individual, or group, outcome of developing
A.I. systems:

http://en.wikipedia.org/wiki/Ethnolinguistics

http://en.wikipedia.org/wiki/Cognitive_anthropology

http://en.wikipedia.org/wiki/Cognitive_science

The latter probably explains what I mean in more depth than the two
formers.


On Mon, Mar 31, 2014 at 8:47 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:

> On Mon, Mar 31, 2014 at 1:31 PM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
> > Op 31-03-14 19:40, Ian Kelly schreef:
> >> That was an exaggeration on my part.  It wouldn't affect my job, as I
> >> wouldn't expect to ever actually have to maintain anything like the
> >> above.  My greater point though is that it damages Python's
> >> readability for no actual gain in my view.  There is nothing useful
> >> you can do with a name that is the U+1F4A9 character that you can't do
> >> just as easily with alphanumeric identifiers like pile_of_poo (or
> >> ????_??????? if one prefers; that's auto-translated, so don't blame me
> >> if it's a poor translation). The kinds of symbols that we're talking
> >> about here aren't part of any writing systems, and so to incorporate
> >> them in *names* as if they were is an abuse of Unicode.
> >
> > Your argument doesn't has much weight. First of all it can be used
> > for just restricting names to the ascii range.
>
> I disagree.  Non-ASCII written names are useful to anybody who prefers
> not to do all their programming in English.
>
> > Second of all I
> > think a good chosen symbolic name can be more readable than a
> > name in a character set you are not familiar with. A good chosen
> > symbol will evoke a meaning with a lot of people. A name in a
> > character set you are not familiar with is just gibberish to
> > you.
>
> Well, this is the path taken by APL.  It has its supporters.  It's not
> known for being readable.
>
> >> I don't think the comparisons to decorators and the if-else operator
> >> are apt.
> >
> > I didn't make such a comparison. I just noted the arguments against
> > were similar.
>
> That's the comparison to which I was referring.
>
> >> First, because while those may degrade readability, they do
> >> so in a constrained way.  A decorator application is just the @ symbol
> >> and an identifier.
> >
> > And if abused, can totally change the working of your function. There
> > is no guarantee that the function returned, has any relation with the
> > original function. If that can't be a night mare for readability,
> > I don't know what is.
>
> As Terry Reedy noted, this has nothing to do with the decorator
> syntax, so it isn't much of an argument against having such syntax.
>
> >> The if-else is just three expressions separated by
> >> keywords.
> >
> > Yes but if used unrestrained in arbitrary expressions will make those
> > expressions hard to understand.
>
> I don't disagree.  I hardly ever use it myself, certainly only if it
> can fit comfortably into one line, which is rare.  But it's still
> quite limited in syntactic scope.
>
> >> In the case of arbitrary Unicode identifiers, we're talking
> >> about approximately doubling the number of different characters (out
> >> of a continuously growing set) that could be used, many of which are
> >> easily confused with other characters. Of course the potential for
> >> confusion already exists, but that's no justification for aggravating
> >> it.
> >
> > So what if we double the number of different characters? I don't care
> > about the number of them, I care about how meaningful they are. And
> > as you say confusion is already possible. A good programmer knows
> > how to deal with such a possible confusion, that the number of
> > cases increases, doesn't need to be a problem for those that care
> > about this.
>
> So tell me then, how would you deal with it?  In the case of script
> identifiers, it's often not hard to discern from context whether a
> particular character is e.g. a Latin h or a Cyrillic ?.  Assuming the
> original author wasn't being intentionally obfuscatory, if the rest of
> the identifier is Cyrillic then the character is probably also
> Cyrillic.  If it's a one-character identifier, then hopefully the rest
> of the module is consistent and you can guess from that.  If the
> identifier in question is just one symbol though, then you have a lot
> less context.
>
> >
> >> Second, at least in the case of decorators, while I don't dispute that
> >> they can harm readability, I think that in the majority of cases they
> >> actually help it.
> >
> > But that is not a fair comparison now, is it. What you are doing here
> > is comparing actual use, to a worst case doom scenario.
>
> I contend that there is no scenario with arbitrary Unicode identifiers
> where readability is improved.
> --
> https://mail.python.org/mailman/listinfo/python-list
>



-- 
Best Regards,
David Hutto
*CEO:* *http://www.hitwebdevelopment.com <http://www.hitwebdevelopment.com>*
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