From tk446 at snu.edu.in  Wed Oct  1 12:37:02 2014
From: tk446 at snu.edu.in (Tarun Kumar)
Date: Wed, 1 Oct 2014 16:07:02 +0530
Subject: [BangPypers] Python for RTOS
Message-ID: <CAGrKnhHyHHQ1HBtG+Mc-L5R-QM_ztsJn6Bi5qxzPnC9=YSd=yA@mail.gmail.com>

Hello all
Greetings from my side.
I am working with ARM 9 + embOS(RTOS) +  Emfile(file system) and I need a
Python interpreter over it. can you guys help me with name of the Python
interpreter. For example I was wondering whether PyMite will work with my
board or not. I can find all compatibility issues online but unable to find
suitability of embOS(RTOS by segger) with python interpreter.



Thanks and regards
-- 

-Tarun Kumar
Shiv Nadar University
----------------------------------------

From vidhishanair at gmail.com  Wed Oct  1 16:46:24 2014
From: vidhishanair at gmail.com (vidhisha nair)
Date: Wed, 1 Oct 2014 20:16:24 +0530
Subject: [BangPypers] Invitation to deliver workshop at PyCampus at PES
	Institute of Technology
Message-ID: <CACzgGwuRaPSi74BphHzL7fOVW-uJ6=9UEhiECe7qLn3an2oQpg@mail.gmail.com>

Hello all!

I'm Vidhisha, a final year student from PES Institute of Technology,
Bangalore and a member of the PES Open Source Community [1].

We are a strong community of 5000+ members based out of PES Institute to
Technology. We actively advocate, evangelize and spread the message on
being open. We help beginners get started with contributing to Open Source.

As part of our activities, we plan to have a Python Workshop 'PyCampus' at
our college for the benefit of our students, so that they can be aware of
the power and use of the language. We would like to have a beginners day of
Python on 19th October, 2014 where we would like all basics of python to be
taught and an advanced day on 2nd November, 2014 where we look into
advanced applications of python like Pandas, Flask, etc.

We had collaborated with the Bangalore Python Users Group last year for the
same event and had an amazing feedback from our students and community.

We would like to request members of this community to once again come in as
speakers for these days so that we can deliver an amazing session to
students at our college. Please feel free to ask me any further details
which I have missed out.

You can contact me on:
vidhishanair at gmail.com
7899364937

[1] PES Open Source Community : http://pesos.pes.edu/

https://www.facebook.com/groups/pesosc/

-- 
Thanks and Regards,
Vidhisha B
PES Open Source Community

From vsapre80 at gmail.com  Wed Oct  1 19:02:21 2014
From: vsapre80 at gmail.com (Vishal)
Date: Wed, 1 Oct 2014 22:32:21 +0530
Subject: [BangPypers] Python for RTOS
In-Reply-To: <CAGrKnhHyHHQ1HBtG+Mc-L5R-QM_ztsJn6Bi5qxzPnC9=YSd=yA@mail.gmail.com>
References: <CAGrKnhHyHHQ1HBtG+Mc-L5R-QM_ztsJn6Bi5qxzPnC9=YSd=yA@mail.gmail.com>
Message-ID: <CACPguY-=pRAXuWm-bWMbqL9wH01ZGzPh9148nhJzeG=qMBEtCw@mail.gmail.com>

Dear Tarun,

your best bet in this case is the support from Segger. I am sure someone
before must have used Python on embOS.
Atleast they can help you compile it for the OS from python source.

Take care,
Vishal Sapre



Thanks and best regards,
Vishal Sapre

---
Please DONT print this email, unless you really need to. Save Energy &
Paper. Save the Earth.

On Wed, Oct 1, 2014 at 4:07 PM, Tarun Kumar <tk446 at snu.edu.in> wrote:

> Hello all
> Greetings from my side.
> I am working with ARM 9 + embOS(RTOS) +  Emfile(file system) and I need a
> Python interpreter over it. can you guys help me with name of the Python
> interpreter. For example I was wondering whether PyMite will work with my
> board or not. I can find all compatibility issues online but unable to find
> suitability of embOS(RTOS by segger) with python interpreter.
>
>
>
> Thanks and regards
> --
>
> -Tarun Kumar
> Shiv Nadar University
> ----------------------------------------
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>

From tk446 at snu.edu.in  Wed Oct  1 19:21:20 2014
From: tk446 at snu.edu.in (Tarun Kumar)
Date: Wed, 1 Oct 2014 22:51:20 +0530
Subject: [BangPypers] Python for RTOS
In-Reply-To: <CACPguY-=pRAXuWm-bWMbqL9wH01ZGzPh9148nhJzeG=qMBEtCw@mail.gmail.com>
References: <CAGrKnhHyHHQ1HBtG+Mc-L5R-QM_ztsJn6Bi5qxzPnC9=YSd=yA@mail.gmail.com>
 <CACPguY-=pRAXuWm-bWMbqL9wH01ZGzPh9148nhJzeG=qMBEtCw@mail.gmail.com>
Message-ID: <CAGrKnhHiFUwjKw+z_DLVvwRB77T5YJBvb4SSp2XhczdyBvOFRQ@mail.gmail.com>

Dear Vishal
I have sent an email to segger regarding same. Thanks for your support.


best
Tarun

On Wed, Oct 1, 2014 at 10:32 PM, Vishal <vsapre80 at gmail.com> wrote:

> Dear Tarun,
>
> your best bet in this case is the support from Segger. I am sure someone
> before must have used Python on embOS.
> Atleast they can help you compile it for the OS from python source.
>
> Take care,
> Vishal Sapre
>
>
>
> Thanks and best regards,
> Vishal Sapre
>
> ---
> Please DONT print this email, unless you really need to. Save Energy &
> Paper. Save the Earth.
>
> On Wed, Oct 1, 2014 at 4:07 PM, Tarun Kumar <tk446 at snu.edu.in> wrote:
>
> > Hello all
> > Greetings from my side.
> > I am working with ARM 9 + embOS(RTOS) +  Emfile(file system) and I need a
> > Python interpreter over it. can you guys help me with name of the Python
> > interpreter. For example I was wondering whether PyMite will work with my
> > board or not. I can find all compatibility issues online but unable to
> find
> > suitability of embOS(RTOS by segger) with python interpreter.
> >
> >
> >
> > Thanks and regards
> > --
> >
> > -Tarun Kumar
> > Shiv Nadar University
> > ----------------------------------------
> > _______________________________________________
> > BangPypers mailing list
> > BangPypers at python.org
> > https://mail.python.org/mailman/listinfo/bangpypers
> >
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>



-- 

-Tarun Kumar
Shiv Nadar University
----------------------------------------

From rajiv.m1991 at gmail.com  Thu Oct  2 12:21:41 2014
From: rajiv.m1991 at gmail.com (Rajiv Subramanian M)
Date: Thu, 2 Oct 2014 15:51:41 +0530
Subject: [BangPypers] Python List Comprehension Question
Message-ID: <CAELut3UNCzgxcAW+Aed16N0RQWy4Rty-Sb=2=+_rs3wxx-3g+Q@mail.gmail.com>

Hello Group,

I'm Rajiv working as web developer in bangalore.

Objective:
We need to convert the list containing integers and nested list of integer
in it
e.g.) x = [[1, 2, [3]], 4]
into a flat list format
e.g.) result = [1, 2, 3, 4]

MyAnswer using Recursive function:
def flat_it(List):
    result = []
    for item in List:
        if type(item) is int:
            result.append(item)
        else:
            result += flat_it(item)
    return result
print flat_it(x)

This actually works, but I tried to optimize this with List comprehension
like the following code, but it never worked

def flat_it(List):
return [item if type(item) is int else flat_it(item) for item in List]
print flat_it(x)

This returns result without flatting like what i passed in argument [[1, 2,
[3]], 4]

please help.

-- 

  [image: --]
Rajiv Subramanian M
[image: http://]about.me/rajiv.m1991
     <http://about.me/rajiv.m1991?promo=email_sig>

From anandology at gmail.com  Thu Oct  2 12:57:31 2014
From: anandology at gmail.com (Anand Chitipothu)
Date: Thu, 2 Oct 2014 16:27:31 +0530
Subject: [BangPypers] Python List Comprehension Question
In-Reply-To: <CAELut3UNCzgxcAW+Aed16N0RQWy4Rty-Sb=2=+_rs3wxx-3g+Q@mail.gmail.com>
References: <CAELut3UNCzgxcAW+Aed16N0RQWy4Rty-Sb=2=+_rs3wxx-3g+Q@mail.gmail.com>
Message-ID: <CAC7wXFy8k2dkX2eJBT91ifdBLmLnT9+LTLEh2Nid0NiJGS-NKw@mail.gmail.com>

On Thu, Oct 2, 2014 at 3:51 PM, Rajiv Subramanian M <rajiv.m1991 at gmail.com>
wrote:

> Hello Group,
>
> I'm Rajiv working as web developer in bangalore.
>
> Objective:
> We need to convert the list containing integers and nested list of integer
> in it
> e.g.) x = [[1, 2, [3]], 4]
> into a flat list format
> e.g.) result = [1, 2, 3, 4]
>
> MyAnswer using Recursive function:
> def flat_it(List):
>     result = []
>     for item in List:
>         if type(item) is int:
>             result.append(item)
>         else:
>             result += flat_it(item)
>     return result
> print flat_it(x)
>
> This actually works, but I tried to optimize this with List comprehension
> like the following code, but it never worked
>
> def flat_it(List):
> return [item if type(item) is int else flat_it(item) for item in List]
> print flat_it(x)
>
> This returns result without flatting like what i passed in argument [[1, 2,
> [3]], 4]
>

List comprehensions take a list and return a list of the same size (if you
don't use if condition).

What you have done is correct solution, though it could be slightly
improved like the following:

def flat_it(values, result=None):
    if result is None:
        result = []

    for v in values:
        if isinstance(v, list):
            flat_it(v, result)
        else:
            result.append(v)
    return result

Improvements:
* using isinstance is better than comparing type.
* avoids creation of intermediate lists by passing the result along the
recursive calls

Anand

From kracethekingmaker at gmail.com  Thu Oct  2 13:45:41 2014
From: kracethekingmaker at gmail.com (kracekumar ramaraju)
Date: Thu, 2 Oct 2014 17:15:41 +0530
Subject: [BangPypers] Python List Comprehension Question
In-Reply-To: <CAC7wXFy8k2dkX2eJBT91ifdBLmLnT9+LTLEh2Nid0NiJGS-NKw@mail.gmail.com>
References: <CAELut3UNCzgxcAW+Aed16N0RQWy4Rty-Sb=2=+_rs3wxx-3g+Q@mail.gmail.com>
 <CAC7wXFy8k2dkX2eJBT91ifdBLmLnT9+LTLEh2Nid0NiJGS-NKw@mail.gmail.com>
Message-ID: <CAO5c=mm8zftLSGitEA4XRX2iB0X-mFChx8LwMfFNUzzUYq3sag@mail.gmail.com>

Hi

`yield from ` is introduced in Python 3.3 as part of pep 380.

# python 3.3

from collections import Iterable

def flatten(items):
    for item in items:
        if isinstance(item, Iterable):
            yield from flatten(item)
        else:
            yield item

list(flatten([[1, 2, [3]], 4]))
[1, 2, 3, 4]

# python 2.7

from collections import Iterable

x = [[1, 2, [3]], 4]

def flatten(items):
    for item in items:
        if isinstance(item, Iterable):
            for subitem in flatten(item):
                yield subitem
        else:
            yield item
   ....:

list(flatten(x))
[1, 2, 3, 4]

PEP 0380: http://legacy.python.org/dev/peps/pep-0380/

P.S: The above approach is discussed in Python 3 CookBook by David Beazley.



On Thu, Oct 2, 2014 at 4:27 PM, Anand Chitipothu <anandology at gmail.com>
wrote:

> On Thu, Oct 2, 2014 at 3:51 PM, Rajiv Subramanian M <rajiv.m1991 at gmail.com
> >
> wrote:
>
> > Hello Group,
> >
> > I'm Rajiv working as web developer in bangalore.
> >
> > Objective:
> > We need to convert the list containing integers and nested list of
> integer
> > in it
> > e.g.) x = [[1, 2, [3]], 4]
> > into a flat list format
> > e.g.) result = [1, 2, 3, 4]
> >
> > MyAnswer using Recursive function:
> > def flat_it(List):
> >     result = []
> >     for item in List:
> >         if type(item) is int:
> >             result.append(item)
> >         else:
> >             result += flat_it(item)
> >     return result
> > print flat_it(x)
> >
> > This actually works, but I tried to optimize this with List comprehension
> > like the following code, but it never worked
> >
> > def flat_it(List):
> > return [item if type(item) is int else flat_it(item) for item in List]
> > print flat_it(x)
> >
> > This returns result without flatting like what i passed in argument [[1,
> 2,
> > [3]], 4]
> >
>
> List comprehensions take a list and return a list of the same size (if you
> don't use if condition).
>
> What you have done is correct solution, though it could be slightly
> improved like the following:
>
> def flat_it(values, result=None):
>     if result is None:
>         result = []
>
>     for v in values:
>         if isinstance(v, list):
>             flat_it(v, result)
>         else:
>             result.append(v)
>     return result
>
> Improvements:
> * using isinstance is better than comparing type.
> * avoids creation of intermediate lists by passing the result along the
> recursive calls
>
> Anand
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>



-- 

*Thanks & Regardskracekumar"Talk is cheap, show me the code" -- Linus
Torvaldshttp://kracekumar.com <http://kracekumar.com>*

From abhishekl.2006 at gmail.com  Thu Oct  2 15:04:44 2014
From: abhishekl.2006 at gmail.com (Abhishek L)
Date: Thu, 2 Oct 2014 18:34:44 +0530
Subject: [BangPypers] Python List Comprehension Question
In-Reply-To: <CAO5c=mm8zftLSGitEA4XRX2iB0X-mFChx8LwMfFNUzzUYq3sag@mail.gmail.com>
References: <CAELut3UNCzgxcAW+Aed16N0RQWy4Rty-Sb=2=+_rs3wxx-3g+Q@mail.gmail.com>
 <CAC7wXFy8k2dkX2eJBT91ifdBLmLnT9+LTLEh2Nid0NiJGS-NKw@mail.gmail.com>
 <CAO5c=mm8zftLSGitEA4XRX2iB0X-mFChx8LwMfFNUzzUYq3sag@mail.gmail.com>
Message-ID: <CAFFrkr+55Bf_EGJuQC7B1C=HJWmpDnrk2P5WGNjKPBPgktTcbQ@mail.gmail.com>

On Thu, Oct 2, 2014 at 5:15 PM, kracekumar ramaraju
<kracethekingmaker at gmail.com> wrote:
> Hi
>
> `yield from ` is introduced in Python 3.3 as part of pep 380.
>
> # python 3.3
>
> from collections import Iterable
>
> def flatten(items):
>     for item in items:
>         if isinstance(item, Iterable):
>             yield from flatten(item)
>         else:
>             yield item

Yield from approach is great if you're using python 3.3+ :)

>
> list(flatten([[1, 2, [3]], 4]))
> [1, 2, 3, 4]
>
> # python 2.7
>
> from collections import Iterable
>
> x = [[1, 2, [3]], 4]
>
> def flatten(items):
>     for item in items:
>         if isinstance(item, Iterable):
>             for subitem in flatten(item):
>                 yield subitem
>         else:
>             yield item
>    ....:
>
> list(flatten(x))
> [1, 2, 3, 4]

Also you may need to check whether the item is not a string or bytes
or a string in the list will break this, an

isinstance(item, Iterable) and not isinstance(item,str) # maybe bytes too

should handle that

--
Abhishek

From kracethekingmaker at gmail.com  Thu Oct  2 15:22:29 2014
From: kracethekingmaker at gmail.com (kracekumar ramaraju)
Date: Thu, 2 Oct 2014 18:52:29 +0530
Subject: [BangPypers] Python List Comprehension Question
In-Reply-To: <CAFFrkr+55Bf_EGJuQC7B1C=HJWmpDnrk2P5WGNjKPBPgktTcbQ@mail.gmail.com>
References: <CAELut3UNCzgxcAW+Aed16N0RQWy4Rty-Sb=2=+_rs3wxx-3g+Q@mail.gmail.com>
 <CAC7wXFy8k2dkX2eJBT91ifdBLmLnT9+LTLEh2Nid0NiJGS-NKw@mail.gmail.com>
 <CAO5c=mm8zftLSGitEA4XRX2iB0X-mFChx8LwMfFNUzzUYq3sag@mail.gmail.com>
 <CAFFrkr+55Bf_EGJuQC7B1C=HJWmpDnrk2P5WGNjKPBPgktTcbQ@mail.gmail.com>
Message-ID: <CAO5c=mn8XZHbVuH4ZjkKbT0YZvOCi4GT2gLdz0Y2GhunCFmcBg@mail.gmail.com>

On Thu, Oct 2, 2014 at 6:34 PM, Abhishek L <abhishekl.2006 at gmail.com> wrote:

> On Thu, Oct 2, 2014 at 5:15 PM, kracekumar ramaraju
> <kracethekingmaker at gmail.com> wrote:
> > Hi
> >
> > `yield from ` is introduced in Python 3.3 as part of pep 380.
> >
> > # python 3.3
> >
> > from collections import Iterable
> >
> > def flatten(items):
> >     for item in items:
> >         if isinstance(item, Iterable):
> >             yield from flatten(item)
> >         else:
> >             yield item
>
> Yield from approach is great if you're using python 3.3+ :)
>
> >
> > list(flatten([[1, 2, [3]], 4]))
> > [1, 2, 3, 4]
> >
> > # python 2.7
> >
> > from collections import Iterable
> >
> > x = [[1, 2, [3]], 4]
> >
> > def flatten(items):
> >     for item in items:
> >         if isinstance(item, Iterable):
> >             for subitem in flatten(item):
> >                 yield subitem
> >         else:
> >             yield item
> >    ....:
> >
> > list(flatten(x))
> > [1, 2, 3, 4]
>
> Also you may need to check whether the item is not a string or bytes
> or a string in the list will break this, an
>
> isinstance(item, Iterable) and not isinstance(item,str) # maybe bytes too
>
>
ah, Yes that is correct. Probably flatten can take ignore_types as an
argument.

condition can be
isinstance(item, Iterable) and not isinstance(item, ignore_types)


should handle that
>
> --
> Abhishek
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>



-- 

*Thanks & Regardskracekumar"Talk is cheap, show me the code" -- Linus
Torvaldshttp://kracekumar.com <http://kracekumar.com>*

From rajiv.m1991 at gmail.com  Thu Oct  2 20:41:18 2014
From: rajiv.m1991 at gmail.com (Rajiv Subramanian M)
Date: Fri, 3 Oct 2014 00:11:18 +0530
Subject: [BangPypers] Python List Comprehension Question
Message-ID: <CAELut3V6OU_5VRqaw1=yWVacgLK7X-6C9fkLpfufSjdkFNJeDQ@mail.gmail.com>

Hi Krace,

I believe as your code returns a generator instance it must be efficient in
handling large input as well.
And as you said in previous reply I've added "not isinstance(item, (str,
bytes))", the code looks like

def flat_it(items):
    for item in items:
        if isinstance(item, Iterable) and not isinstance(item, (str,
bytes)):
            for subitem in flat_it(item):
                yield subitem
        else:
            yield item

and it works fine.


But is there any possibilities to use "List Comprehension" methodology ?


def flat_it(items):

    return [item for item in items if not isinstance(item, Iterable) *else
flat_it(item)*]


The above solution should be possible, but unfortunately list comprehension
syntax dosen't allows an extra else condition (mentioned in bold letters
above).



-- 

  [image: --]
Rajiv Subramanian M
[image: http://]about.me/rajiv.m1991
     <http://about.me/rajiv.m1991?promo=email_sig>

From noufal at nibrahim.net.in  Thu Oct  2 10:56:16 2014
From: noufal at nibrahim.net.in (Noufal Ibrahim KV)
Date: Thu, 02 Oct 2014 14:26:16 +0530
Subject: [BangPypers] Return values
In-Reply-To: <CADfLaaB42K-G2ffbHo-gTFgNixc-95PVqASzaC4NnCMiXFDW3w@mail.gmail.com>
 (Saager Mhatre's message of "Wed, 24 Sep 2014 23:02:25 -0400")
References: <87ioki7jda.fsf@nibrahim.net.in>
 <CAC7wXFwT2W+V9CtfFbf5skvresmreC2vf4SvH8HYXBRwP-_JKQ@mail.gmail.com>
 <87wq8y5zrg.fsf@nibrahim.net.in>
 <CADfLaaB42K-G2ffbHo-gTFgNixc-95PVqASzaC4NnCMiXFDW3w@mail.gmail.com>
Message-ID: <87h9zmu9xr.fsf@nibrahim.net.in>

On Thu, Sep 25 2014, Saager Mhatre wrote:


[...]

> Alternatively, would it be possible to model Stats/StatsList as a composite
> hierarchy (potentially with Courtesy Implementations
> <http://martinfowler.com/bliki/CourtesyImplementation.html>)?

[...]

I didn't know about Courtesy implementations till now. Thanks. 

I'm not really convinced with Fowlers argument and I didn't like the
solution but it's still an interesting patterns.

-- 
Cordially,
Noufal
http://nibrahim.net.in

From noufal at nibrahim.net.in  Thu Oct  2 10:56:21 2014
From: noufal at nibrahim.net.in (Noufal Ibrahim KV)
Date: Thu, 02 Oct 2014 14:26:21 +0530
Subject: [BangPypers] Return values
In-Reply-To: <CADfLaaB42K-G2ffbHo-gTFgNixc-95PVqASzaC4NnCMiXFDW3w@mail.gmail.com>
 (Saager Mhatre's message of "Wed, 24 Sep 2014 23:02:25 -0400")
References: <87ioki7jda.fsf@nibrahim.net.in>
 <CAC7wXFwT2W+V9CtfFbf5skvresmreC2vf4SvH8HYXBRwP-_JKQ@mail.gmail.com>
 <87wq8y5zrg.fsf@nibrahim.net.in>
 <CADfLaaB42K-G2ffbHo-gTFgNixc-95PVqASzaC4NnCMiXFDW3w@mail.gmail.com>
Message-ID: <87eguqu9xm.fsf@nibrahim.net.in>

On Thu, Sep 25 2014, Saager Mhatre wrote:


[...]

> Alternatively, would it be possible to model Stats/StatsList as a composite
> hierarchy (potentially with Courtesy Implementations
> <http://martinfowler.com/bliki/CourtesyImplementation.html>)?

[...]

I didn't know about Courtesy implementations till now. Thanks. 

I'm not really convinced with Fowlers argument and I didn't like the
solution but it's still an interesting pattern.

-- 
Cordially,
Noufal
http://nibrahim.net.in

From bhargav.kowshik at yahoo.com  Fri Oct  3 16:56:33 2014
From: bhargav.kowshik at yahoo.com (Bhargav Kowshik)
Date: Fri, 3 Oct 2014 14:56:33 +0000 (UTC)
Subject: [BangPypers] Python List Comprehension Question
In-Reply-To: <CAC7wXFy8k2dkX2eJBT91ifdBLmLnT9+LTLEh2Nid0NiJGS-NKw@mail.gmail.com>
References: <CAELut3UNCzgxcAW+Aed16N0RQWy4Rty-Sb=2=+_rs3wxx-3g+Q@mail.gmail.com>
 <CAC7wXFy8k2dkX2eJBT91ifdBLmLnT9+LTLEh2Nid0NiJGS-NKw@mail.gmail.com>
Message-ID: <2022172401.234739.1412348193736.JavaMail.yahoo@jws10001g.mail.ne1.yahoo.com>

We could use what Anand talked about at Pycon India about handling the headers in first row of a CSV.In this scenario, instead of default for result being None and checking if None everytime, we could have the default value an empty list.

def flat_it(values, result=list()):
??? for v in values:
??????? if isinstance(v, list):
??????????? flat_it(v, result)
??????? else:
??????????? result.append(v)
??? return result

x = [[1, 2, [3, 4, 5, 6, 7]], 4]
print x
print flat_it(x) 

?Thank you,
Bhargav.
 

     On Thursday, October 2, 2014 4:27 PM, Anand Chitipothu <anandology at gmail.com> wrote:
   
 

 On Thu, Oct 2, 2014 at 3:51 PM, Rajiv Subramanian M <rajiv.m1991 at gmail.com>
wrote:

> Hello Group,
>
> I'm Rajiv working as web developer in bangalore.
>
> Objective:
> We need to convert the list containing integers and nested list of integer
> in it
> e.g.) x = [[1, 2, [3]], 4]
> into a flat list format
> e.g.) result = [1, 2, 3, 4]
>
> MyAnswer using Recursive function:
> def flat_it(List):
>? ? result = []
>? ? for item in List:
>? ? ? ? if type(item) is int:
>? ? ? ? ? ? result.append(item)
>? ? ? ? else:
>? ? ? ? ? ? result += flat_it(item)
>? ? return result
> print flat_it(x)
>
> This actually works, but I tried to optimize this with List comprehension
> like the following code, but it never worked
>
> def flat_it(List):
> return [item if type(item) is int else flat_it(item) for item in List]
> print flat_it(x)
>
> This returns result without flatting like what i passed in argument [[1, 2,
> [3]], 4]
>

List comprehensions take a list and return a list of the same size (if you
don't use if condition).

What you have done is correct solution, though it could be slightly
improved like the following:

def flat_it(values, result=None):
? ? if result is None:
? ? ? ? result = []

? ? for v in values:
? ? ? ? if isinstance(v, list):
? ? ? ? ? ? flat_it(v, result)
? ? ? ? else:
? ? ? ? ? ? result.append(v)
? ? return result

Improvements:
* using isinstance is better than comparing type.
* avoids creation of intermediate lists by passing the result along the
recursive calls

Anand
_______________________________________________
BangPypers mailing list
BangPypers at python.org
https://mail.python.org/mailman/listinfo/bangpypers


 
   

From anandology at gmail.com  Fri Oct  3 17:18:02 2014
From: anandology at gmail.com (Anand Chitipothu)
Date: Fri, 3 Oct 2014 20:48:02 +0530
Subject: [BangPypers] Python List Comprehension Question
In-Reply-To: <2022172401.234739.1412348193736.JavaMail.yahoo@jws10001g.mail.ne1.yahoo.com>
References: <CAELut3UNCzgxcAW+Aed16N0RQWy4Rty-Sb=2=+_rs3wxx-3g+Q@mail.gmail.com>
 <CAC7wXFy8k2dkX2eJBT91ifdBLmLnT9+LTLEh2Nid0NiJGS-NKw@mail.gmail.com>
 <2022172401.234739.1412348193736.JavaMail.yahoo@jws10001g.mail.ne1.yahoo.com>
Message-ID: <CAC7wXFzY=JWnFaRM=fBtWQqCJOuWr3F076ZSFQRymSwzShiYRQ@mail.gmail.com>

On Fri, Oct 3, 2014 at 8:26 PM, Bhargav Kowshik <
bhargav.kowshik at yahoo.com.dmarc.invalid> wrote:

> We could use what Anand talked about at Pycon India about handling the
> headers in first row of a CSV.In this scenario, instead of default for
> result being None and checking if None everytime, we could have the default
> value an empty list.
>
> def flat_it(values, result=list()):
>     for v in values:
>         if isinstance(v, list):
>             flat_it(v, result)
>         else:
>             result.append(v)
>     return result
>
> x = [[1, 2, [3, 4, 5, 6, 7]], 4]
> print x
> print flat_it(x)
>

Thats a pitfall! Try calling flat_it once again and see what you get.

Anand

From bhargav.kowshik at yahoo.com  Fri Oct  3 17:34:39 2014
From: bhargav.kowshik at yahoo.com (Bhargav Kowshik)
Date: Fri, 3 Oct 2014 15:34:39 +0000 (UTC)
Subject: [BangPypers] Python List Comprehension Question
In-Reply-To: <CAC7wXFzY=JWnFaRM=fBtWQqCJOuWr3F076ZSFQRymSwzShiYRQ@mail.gmail.com>
References: <CAC7wXFzY=JWnFaRM=fBtWQqCJOuWr3F076ZSFQRymSwzShiYRQ@mail.gmail.com>
Message-ID: <803376319.247924.1412350479548.JavaMail.yahoo@jws10032.mail.ne1.yahoo.com>

Nice! Thank you very much Anand.But, I still don't know what is happening.Please point me to a resource to understand what is happening.

** Program **

def flat_it(values, result=list()):
??? for v in values:
??????? if isinstance(v, list):
??????????? flat_it(v, result)
??????? else:
??????????? result.append(v)
??? return result

x = [[1, 2, [3, 7]], 4]

print('Input: {0}'.format(x))
print('Output 1: {0}'.format(flat_it(x)))
print('Output 2: {0}'.format(flat_it(x)))
print('Output 3: {0}'.format(flat_it(x, list())))

** Output **
Input: [[1, 2, [3, 7]], 4]
Output 1: [1, 2, 3, 7, 4]
Output 2: [1, 2, 3, 7, 4, 1, 2, 3, 7, 4]
Output 3: [1, 2, 3, 7, 4]
 
Thank you,
Bhargav.
 

     On Friday, October 3, 2014 8:48 PM, Anand Chitipothu <anandology at gmail.com> wrote:
   
 

 On Fri, Oct 3, 2014 at 8:26 PM, Bhargav Kowshik <bhargav.kowshik at yahoo.com.dmarc.invalid> wrote:

We could use what Anand talked about at Pycon India about handling the headers in first row of a CSV.In this scenario, instead of default for result being None and checking if None everytime, we could have the default value an empty list.

def flat_it(values, result=list()):
??? for v in values:
??????? if isinstance(v, list):
??????????? flat_it(v, result)
??????? else:
??????????? result.append(v)
??? return result

x = [[1, 2, [3, 4, 5, 6, 7]], 4]
print x
print flat_it(x)


Thats a pitfall! Try calling flat_it once again and see what you get.
Anand

 
   

From kracethekingmaker at gmail.com  Fri Oct  3 17:48:03 2014
From: kracethekingmaker at gmail.com (kracekumar ramaraju)
Date: Fri, 3 Oct 2014 21:18:03 +0530
Subject: [BangPypers] Python List Comprehension Question
In-Reply-To: <803376319.247924.1412350479548.JavaMail.yahoo@jws10032.mail.ne1.yahoo.com>
References: <CAC7wXFzY=JWnFaRM=fBtWQqCJOuWr3F076ZSFQRymSwzShiYRQ@mail.gmail.com>
 <803376319.247924.1412350479548.JavaMail.yahoo@jws10032.mail.ne1.yahoo.com>
Message-ID: <CAO5c=mm8=zP1WavUv46EaanaXpzE7-e958EoB+EMiaavcA77vg@mail.gmail.com>

On Fri, Oct 3, 2014 at 9:04 PM, Bhargav Kowshik <
bhargav.kowshik at yahoo.com.dmarc.invalid> wrote:

> Nice! Thank you very much Anand.But, I still don't know what is
> happening.Please point me to a resource to understand what is happening.
>
>
A common beginner mistake. More of such gotcha can be found here
http://docs.python-guide.org/en/latest/writing/gotchas/ .



> ** Program **
>
> def flat_it(values, result=list()):
>     for v in values:
>         if isinstance(v, list):
>             flat_it(v, result)
>         else:
>             result.append(v)
>     return result
>
> x = [[1, 2, [3, 7]], 4]
>
> print('Input: {0}'.format(x))
> print('Output 1: {0}'.format(flat_it(x)))
> print('Output 2: {0}'.format(flat_it(x)))
> print('Output 3: {0}'.format(flat_it(x, list())))
>
> ** Output **
> Input: [[1, 2, [3, 7]], 4]
> Output 1: [1, 2, 3, 7, 4]
> Output 2: [1, 2, 3, 7, 4, 1, 2, 3, 7, 4]
> Output 3: [1, 2, 3, 7, 4]
>
> Thank you,
> Bhargav.
>
>
>      On Friday, October 3, 2014 8:48 PM, Anand Chitipothu <
> anandology at gmail.com> wrote:
>
>
>
>  On Fri, Oct 3, 2014 at 8:26 PM, Bhargav Kowshik
> <bhargav.kowshik at yahoo.com.dmarc.invalid> wrote:
>
> We could use what Anand talked about at Pycon India about handling the
> headers in first row of a CSV.In this scenario, instead of default for
> result being None and checking if None everytime, we could have the default
> value an empty list.
>
> def flat_it(values, result=list()):
>     for v in values:
>         if isinstance(v, list):
>             flat_it(v, result)
>         else:
>             result.append(v)
>     return result
>
> x = [[1, 2, [3, 4, 5, 6, 7]], 4]
> print x
> print flat_it(x)
>
>
> Thats a pitfall! Try calling flat_it once again and see what you get.
> Anand
>
>
>
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>



-- 

*Thanks & Regardskracekumar"Talk is cheap, show me the code" -- Linus
Torvaldshttp://kracekumar.com <http://kracekumar.com>*

From bhargav.kowshik at yahoo.com  Fri Oct  3 18:09:31 2014
From: bhargav.kowshik at yahoo.com (Bhargav Kowshik)
Date: Fri, 3 Oct 2014 16:09:31 +0000 (UTC)
Subject: [BangPypers] Python List Comprehension Question
In-Reply-To: <CAO5c=mm8=zP1WavUv46EaanaXpzE7-e958EoB+EMiaavcA77vg@mail.gmail.com>
References: <CAO5c=mm8=zP1WavUv46EaanaXpzE7-e958EoB+EMiaavcA77vg@mail.gmail.com>
Message-ID: <1533201105.216967.1412352571425.JavaMail.yahoo@jws10051.mail.ne1.yahoo.com>

Thank you Kracekumar.

http://docs.python-guide.org/en/latest/writing/gotchas/#what-you-wrote"Python?s default arguments are evaluated once when the function is defined,not each time the function is called."?Thank you,
Bhargav.
 

     On Friday, October 3, 2014 9:18 PM, kracekumar ramaraju <kracethekingmaker at gmail.com> wrote:
   
 

 

On Fri, Oct 3, 2014 at 9:04 PM, Bhargav Kowshik <bhargav.kowshik at yahoo.com.dmarc.invalid> wrote:

Nice! Thank you very much Anand.But, I still don't know what is happening.Please point me to a resource to understand what is happening.



A common beginner mistake. More of such gotcha can be found here?http://docs.python-guide.org/en/latest/writing/gotchas/ .
?
** Program **

def flat_it(values, result=list()):
??? for v in values:
??????? if isinstance(v, list):
??????????? flat_it(v, result)
??????? else:
??????????? result.append(v)
??? return result

x = [[1, 2, [3, 7]], 4]

print('Input: {0}'.format(x))
print('Output 1: {0}'.format(flat_it(x)))
print('Output 2: {0}'.format(flat_it(x)))
print('Output 3: {0}'.format(flat_it(x, list())))

** Output **
Input: [[1, 2, [3, 7]], 4]
Output 1: [1, 2, 3, 7, 4]
Output 2: [1, 2, 3, 7, 4, 1, 2, 3, 7, 4]
Output 3: [1, 2, 3, 7, 4]

Thank you,
Bhargav.


? ? ?On Friday, October 3, 2014 8:48 PM, Anand Chitipothu <anandology at gmail.com> wrote:



?On Fri, Oct 3, 2014 at 8:26 PM, Bhargav Kowshik <bhargav.kowshik at yahoo.com.dmarc.invalid> wrote:

We could use what Anand talked about at Pycon India about handling the headers in first row of a CSV.In this scenario, instead of default for result being None and checking if None everytime, we could have the default value an empty list.

def flat_it(values, result=list()):
??? for v in values:
??????? if isinstance(v, list):
??????????? flat_it(v, result)
??????? else:
??????????? result.append(v)
??? return result

x = [[1, 2, [3, 4, 5, 6, 7]], 4]
print x
print flat_it(x)


Thats a pitfall! Try calling flat_it once again and see what you get.
Anand



_______________________________________________
BangPypers mailing list
BangPypers at python.org
https://mail.python.org/mailman/listinfo/bangpypers




-- 
Thanks & Regards
kracekumar"Talk is cheap, show me the code" -- Linus Torvaldshttp://kracekumar.com

 
   

From rajiv.m1991 at gmail.com  Sat Oct  4 13:27:50 2014
From: rajiv.m1991 at gmail.com (Rajiv Subramanian M)
Date: Sat, 4 Oct 2014 16:57:50 +0530
Subject: [BangPypers] Python Gotcha Fibonacci
Message-ID: <CAELut3VGNQdt5kHEP-qps5m0hOV9JazsV+0W+yB6efwqP-gU3w@mail.gmail.com>

Hi Group,

I just went through this article
http://docs.python-guide.org/en/latest/writing/gotchas/

written a Fibonacci program like this

def fibonacci(next=[1], prev=[0]):
    data = prev.pop()
    prev.append(next.pop())
    next.append(prev[0] + data)
    return data

for i in range(10):
    print fibonacci()

It actually works, it prints first 10 fibonacci numbers

My question is the following code doesn't work the same way as i expected
it to work.

def fibonacci(next=1, prev=0):
    data = prev
    prev = next
    next = data + next
    return data

for i in range(10):
    print fibonacci()

Instead of printing Fibonacci, it just prints 10 zeros

means.. does python only remembers the list in default argument?

-- 

  [image: --]
Rajiv Subramanian M
[image: http://]about.me/rajiv.m1991
     <http://about.me/rajiv.m1991?promo=email_sig>

From shankhabanerjee at gmail.com  Sat Oct  4 13:35:36 2014
From: shankhabanerjee at gmail.com (shankha)
Date: Sat, 4 Oct 2014 17:05:36 +0530
Subject: [BangPypers] Python Gotcha Fibonacci
In-Reply-To: <CAELut3VGNQdt5kHEP-qps5m0hOV9JazsV+0W+yB6efwqP-gU3w@mail.gmail.com>
References: <CAELut3VGNQdt5kHEP-qps5m0hOV9JazsV+0W+yB6efwqP-gU3w@mail.gmail.com>
Message-ID: <CAO_L6qFtYVpzX-J3VnL+RwNJpBAaaaqNic0Q9cxJbiOobULq5w@mail.gmail.com>

Try using pdb. Check the values of next and prev when it is called for
the second time. Similarly check the values of next and prev in
another execution.
You will enjoy it :-).

Try going through this answer:
http://stackoverflow.com/questions/1132941/least-astonishment-in-python-the-mutable-default-argument.


Thanks
Shankha Banerjee


On Sat, Oct 4, 2014 at 4:57 PM, Rajiv Subramanian M
<rajiv.m1991 at gmail.com> wrote:
> Hi Group,
>
> I just went through this article
> http://docs.python-guide.org/en/latest/writing/gotchas/
>
> written a Fibonacci program like this
>
> def fibonacci(next=[1], prev=[0]):
>     data = prev.pop()
>     prev.append(next.pop())
>     next.append(prev[0] + data)
>     return data
>
> for i in range(10):
>     print fibonacci()
>
> It actually works, it prints first 10 fibonacci numbers
>
> My question is the following code doesn't work the same way as i expected
> it to work.
>
> def fibonacci(next=1, prev=0):
>     data = prev
>     prev = next
>     next = data + next
>     return data
>
> for i in range(10):
>     print fibonacci()
>
> Instead of printing Fibonacci, it just prints 10 zeros
>
> means.. does python only remembers the list in default argument?
>
> --
>
>   [image: --]
> Rajiv Subramanian M
> [image: http://]about.me/rajiv.m1991
>      <http://about.me/rajiv.m1991?promo=email_sig>
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers

From anandology at gmail.com  Sun Oct  5 03:08:44 2014
From: anandology at gmail.com (Anand Chitipothu)
Date: Sun, 5 Oct 2014 06:38:44 +0530
Subject: [BangPypers] Python Gotcha Fibonacci
In-Reply-To: <CAO_L6qFtYVpzX-J3VnL+RwNJpBAaaaqNic0Q9cxJbiOobULq5w@mail.gmail.com>
References: <CAELut3VGNQdt5kHEP-qps5m0hOV9JazsV+0W+yB6efwqP-gU3w@mail.gmail.com>
 <CAO_L6qFtYVpzX-J3VnL+RwNJpBAaaaqNic0Q9cxJbiOobULq5w@mail.gmail.com>
Message-ID: <CAC7wXFx13UEWvUVQJMAa4D_=MHbfkv-N+WLJn+NfZPLrJgoypQ@mail.gmail.com>

On Sat, Oct 4, 2014 at 5:05 PM, shankha <shankhabanerjee at gmail.com> wrote:

> Try using pdb.

[...]

Oh no! Real programmers use print.

Anand

From saager.mhatre at gmail.com  Mon Oct  6 17:25:43 2014
From: saager.mhatre at gmail.com (Saager Mhatre)
Date: Mon, 6 Oct 2014 11:25:43 -0400
Subject: [BangPypers] Python Gotcha Fibonacci
In-Reply-To: <CAELut3VGNQdt5kHEP-qps5m0hOV9JazsV+0W+yB6efwqP-gU3w@mail.gmail.com>
References: <CAELut3VGNQdt5kHEP-qps5m0hOV9JazsV+0W+yB6efwqP-gU3w@mail.gmail.com>
Message-ID: <CADfLaaCD0UiT7RyR_YQsWbACo1dV+3ZDZbrVxYbu_WRnZ5yShw@mail.gmail.com>

Spend some time to logically think about what is semantically different in
the two implementations, focus on the types of the values and operations
invoked thereon.

- d

From shyran at gmail.com  Tue Oct  7 12:23:04 2014
From: shyran at gmail.com (Kulkarni, Shreyas)
Date: Tue, 7 Oct 2014 15:53:04 +0530
Subject: [BangPypers] Moving from python 2.6 to 2.7
Message-ID: <C3D38E16-8288-4D1E-8BEA-9BD16B867106@gmail.com>

Hi guys,

We are planning to move our production environment from 2.6 to 2.7 on one of the projects. While I understand it's not a significant upgrade, this being a production environment, I was wondering what aspects of 2.6 might break under 2.7 and what I should be watching out for. I tried searching about it, but didn't hit anything useful. 

Anyone here has any suggestions, or has experienced any difficulties after bumping the version to 2.7? 

Thanks in advance. 


shreyas  

From abdulmuneer at gmail.com  Wed Oct  8 07:42:40 2014
From: abdulmuneer at gmail.com (Abdul Muneer)
Date: Wed, 8 Oct 2014 11:12:40 +0530
Subject: [BangPypers] Moving from python 2.6 to 2.7
In-Reply-To: <C3D38E16-8288-4D1E-8BEA-9BD16B867106@gmail.com>
References: <C3D38E16-8288-4D1E-8BEA-9BD16B867106@gmail.com>
Message-ID: <CAMJTfg=roSic5FswxrQ5MBON6UAWXSZMSG-U7W51QMZpWJC4bQ@mail.gmail.com>

Hi,
As far as I know, nothing written in python should break. If you are
upgrading OS too, then you should be watchful as some of the c libraries
can introduce version conflicts.
We had faced such a problem with pyactivemq at our office. Pyactivemq
depends on activemq-cpp library which in turn depends on a few system
libraries. The problem was that the development of pyactivemq stagnated
while activemq-cpp moved on the version checks caused conflicts. If I used
a version of activemq-cpp that satisfies pyactivemq, activemq-cpp had
problems with system libraries as they too had moved on to newer versions.
IIRC, I solved it by changing the regex that looks for the versions.
Regards,
Abdul Muneer

Regards,
Abdul Muneer

--
Follow me on Twitter: @abdulmuneer <http://twitter.com/#%21/abdulmuneer>

On Tue, Oct 7, 2014 at 3:53 PM, Kulkarni, Shreyas <shyran at gmail.com> wrote:

> Hi guys,
>
> We are planning to move our production environment from 2.6 to 2.7 on one
> of the projects. While I understand it's not a significant upgrade, this
> being a production environment, I was wondering what aspects of 2.6 might
> break under 2.7 and what I should be watching out for. I tried searching
> about it, but didn't hit anything useful.
>
> Anyone here has any suggestions, or has experienced any difficulties after
> bumping the version to 2.7?
>
> Thanks in advance.
>
>
> shreyas
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>

From awasekhirni at gmail.com  Wed Oct  8 07:53:33 2014
From: awasekhirni at gmail.com (Syed Awase khirni)
Date: Wed, 8 Oct 2014 11:23:33 +0530
Subject: [BangPypers] Moving from python 2.6 to 2.7
In-Reply-To: <CAMJTfg=roSic5FswxrQ5MBON6UAWXSZMSG-U7W51QMZpWJC4bQ@mail.gmail.com>
References: <C3D38E16-8288-4D1E-8BEA-9BD16B867106@gmail.com>
 <CAMJTfg=roSic5FswxrQ5MBON6UAWXSZMSG-U7W51QMZpWJC4bQ@mail.gmail.com>
Message-ID: <CAFkQYDVAZwveJ_xgEVBUVG3Af8u56a3Em+H8qfX5o-q=sXZ-mQ@mail.gmail.com>

hello,

We are looking for exceptional programmers in Django, Python,
MySQL,Postgres. freshers to 3+ years work experience. If you are recent
passout, we would train you on the technologies and hire you subjected to
performance. Please share your CVs

regards
Dr. Syed

On Wed, Oct 8, 2014 at 11:12 AM, Abdul Muneer <abdulmuneer at gmail.com> wrote:

> Hi,
> As far as I know, nothing written in python should break. If you are
> upgrading OS too, then you should be watchful as some of the c libraries
> can introduce version conflicts.
> We had faced such a problem with pyactivemq at our office. Pyactivemq
> depends on activemq-cpp library which in turn depends on a few system
> libraries. The problem was that the development of pyactivemq stagnated
> while activemq-cpp moved on the version checks caused conflicts. If I used
> a version of activemq-cpp that satisfies pyactivemq, activemq-cpp had
> problems with system libraries as they too had moved on to newer versions.
> IIRC, I solved it by changing the regex that looks for the versions.
> Regards,
> Abdul Muneer
>
> Regards,
> Abdul Muneer
>
> --
> Follow me on Twitter: @abdulmuneer <http://twitter.com/#%21/abdulmuneer>
>
> On Tue, Oct 7, 2014 at 3:53 PM, Kulkarni, Shreyas <shyran at gmail.com>
> wrote:
>
> > Hi guys,
> >
> > We are planning to move our production environment from 2.6 to 2.7 on one
> > of the projects. While I understand it's not a significant upgrade, this
> > being a production environment, I was wondering what aspects of 2.6 might
> > break under 2.7 and what I should be watching out for. I tried searching
> > about it, but didn't hit anything useful.
> >
> > Anyone here has any suggestions, or has experienced any difficulties
> after
> > bumping the version to 2.7?
> >
> > Thanks in advance.
> >
> >
> > shreyas
> > _______________________________________________
> > BangPypers mailing list
> > BangPypers at python.org
> > https://mail.python.org/mailman/listinfo/bangpypers
> >
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>



-- 
-----------------------------------------------------------------------------------------------------------------------------------------------------
Awase Khirni Syed Ph.D (GIS, University of Zurich), M.E (BITS,Pilani).
Mobile: 0091-9035433124
Tel: 0091-80-42116134

From gora at mimirtech.com  Wed Oct  8 08:35:20 2014
From: gora at mimirtech.com (Gora Mohanty)
Date: Wed, 8 Oct 2014 12:05:20 +0530
Subject: [BangPypers] Moving from python 2.6 to 2.7
In-Reply-To: <C3D38E16-8288-4D1E-8BEA-9BD16B867106@gmail.com>
References: <C3D38E16-8288-4D1E-8BEA-9BD16B867106@gmail.com>
Message-ID: <CACiMRG+Ot8v9NPLcfjPqJz_UKFdyoe3YSEc=jazgXY8v3tbwNg@mail.gmail.com>

On 7 October 2014 15:53, Kulkarni, Shreyas <shyran at gmail.com> wrote:
> Hi guys,
>
> We are planning to move our production environment from 2.6 to 2.7 on one of the projects. While I understand it's not a significant upgrade, this being a production environment, I was wondering what aspects of 2.6 might break under 2.7 and what I should be watching out for. I tried searching about it, but didn't hit anything useful.

You should take a look at https://docs.python.org/3/whatsnew/2.7.html , and as
always should have test cases that should uncover any issues in the migration.

One thing to watch out for is that if you have bytecode (.pyc) files,
it is quite
possible that they will be incompatible between 2.6 and 2.7.

Regards,
Gora

From shyran at gmail.com  Wed Oct  8 11:23:39 2014
From: shyran at gmail.com (Kulkarni, Shreyas)
Date: Wed, 8 Oct 2014 14:53:39 +0530
Subject: [BangPypers] Moving from python 2.6 to 2.7
In-Reply-To: <CAMJTfg=roSic5FswxrQ5MBON6UAWXSZMSG-U7W51QMZpWJC4bQ@mail.gmail.com>
References: <C3D38E16-8288-4D1E-8BEA-9BD16B867106@gmail.com>
 <CAMJTfg=roSic5FswxrQ5MBON6UAWXSZMSG-U7W51QMZpWJC4bQ@mail.gmail.com>
Message-ID: <D9613584-478B-4DEF-AC32-C411875BA5DF@gmail.com>

Thanks Abdul. Fortunately we don't have any native bindings in the project. 

shreyas 

On Oct 8, 2014, at 11:12 AM, Abdul Muneer <abdulmuneer at gmail.com> wrote:

> Hi,
> As far as I know, nothing written in python should break. If you are
> upgrading OS too, then you should be watchful as some of the c libraries
> can introduce version conflicts.
> We had faced such a problem with pyactivemq at our office. Pyactivemq
> depends on activemq-cpp library which in turn depends on a few system
> libraries. The problem was that the development of pyactivemq stagnated
> while activemq-cpp moved on the version checks caused conflicts. If I used
> a version of activemq-cpp that satisfies pyactivemq, activemq-cpp had
> problems with system libraries as they too had moved on to newer versions.
> IIRC, I solved it by changing the regex that looks for the versions.
> Regards,
> Abdul Muneer
> 
> Regards,
> Abdul Muneer
> 
> --
> Follow me on Twitter: @abdulmuneer <http://twitter.com/#%21/abdulmuneer>
> 
> On Tue, Oct 7, 2014 at 3:53 PM, Kulkarni, Shreyas <shyran at gmail.com> wrote:
> 
>> Hi guys,
>> 
>> We are planning to move our production environment from 2.6 to 2.7 on one
>> of the projects. While I understand it's not a significant upgrade, this
>> being a production environment, I was wondering what aspects of 2.6 might
>> break under 2.7 and what I should be watching out for. I tried searching
>> about it, but didn't hit anything useful.
>> 
>> Anyone here has any suggestions, or has experienced any difficulties after
>> bumping the version to 2.7?
>> 
>> Thanks in advance.
>> 
>> 
>> shreyas
>> _______________________________________________
>> BangPypers mailing list
>> BangPypers at python.org
>> https://mail.python.org/mailman/listinfo/bangpypers
>> 
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers


From shyran at gmail.com  Wed Oct  8 11:28:06 2014
From: shyran at gmail.com (Kulkarni, Shreyas)
Date: Wed, 8 Oct 2014 14:58:06 +0530
Subject: [BangPypers] Moving from python 2.6 to 2.7
In-Reply-To: <CACiMRG+Ot8v9NPLcfjPqJz_UKFdyoe3YSEc=jazgXY8v3tbwNg@mail.gmail.com>
References: <C3D38E16-8288-4D1E-8BEA-9BD16B867106@gmail.com>
 <CACiMRG+Ot8v9NPLcfjPqJz_UKFdyoe3YSEc=jazgXY8v3tbwNg@mail.gmail.com>
Message-ID: <9F76A679-F386-4BB2-B44A-C474655D3E0C@gmail.com>

Thanks Gora. The test-cases are scant, at least I don't think they cover it all, and me being new to the functionality, I started looking out for inputs to avoid some deprecations across versions breaking a corner case somewhere. 

shreyas 


On Oct 8, 2014, at 12:05 PM, Gora Mohanty <gora at mimirtech.com> wrote:

> On 7 October 2014 15:53, Kulkarni, Shreyas <shyran at gmail.com> wrote:
>> Hi guys,
>> 
>> We are planning to move our production environment from 2.6 to 2.7 on one of the projects. While I understand it's not a significant upgrade, this being a production environment, I was wondering what aspects of 2.6 might break under 2.7 and what I should be watching out for. I tried searching about it, but didn't hit anything useful.
> 
> You should take a look at https://docs.python.org/3/whatsnew/2.7.html , and as
> always should have test cases that should uncover any issues in the migration.
> 
> One thing to watch out for is that if you have bytecode (.pyc) files,
> it is quite
> possible that they will be incompatible between 2.6 and 2.7.
> 
> Regards,
> Gora
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers


From avinashsajjan at gmail.com  Wed Oct  8 12:44:46 2014
From: avinashsajjan at gmail.com (avinash sajjanshetty)
Date: Wed, 8 Oct 2014 16:14:46 +0530
Subject: [BangPypers] Where to buy Python merchandise in India?
Message-ID: <CAKNZHK9qJ8-gmaP6rbxde=5gp+=b5_BXoR9_ZUAtD_4eYfYwMA@mail.gmail.com>

Where can I buy Python T Shirts and mugs in India? Most of the online sites
I found were from abroad and shipping/tax kills the whole deal. And also
they were pretty costly.

Are there any online sites in India which sell Python merch?

Thanks,
avi

From anandology at gmail.com  Wed Oct  8 12:49:06 2014
From: anandology at gmail.com (Anand Chitipothu)
Date: Wed, 8 Oct 2014 16:19:06 +0530
Subject: [BangPypers] Adding mixing at run-time
Message-ID: <CAC7wXFydyAOfx4mtE6QQjaoi6yNgPjiO7CUZ698peso3iAvJ=g@mail.gmail.com>

Hi,

I'm working on a slightly large application and I'm trying to model it as a
some kind of plugin architecture so that it modular and I can enable or
take out features without lot of code changes.

One of the issues I faced was that the wanted to add some methods to a
class only when a feature/plugin is enabled.

Here is a simplified version of what I have:

class Place(Mixable):
    def __init__(self, name):
        self.name = name

    def get_users(self):
        return "users-of-{}".format(self.name)

    def get_links(self):
        return "links-of-{}".format(self.name)

There are couple of issues with this.

1. The logic for computing users or links doesn't really belong to this
file. I wanted to that in a separate module for modularity.

2. The Place class will become too large to manage over time.

So, I came up with the following approach to address these issues.

# place.py

class Mixable(object):
    """Magic class to allow adding mixins to the class at run-time.
    """
    @classmethod
    def mixin(cls, mixin):
        """Decorator to add a mixin to the class runtime.
        """
        cls.__bases__ = cls.__bases__ + (mixin,)

class Place(Mixable):
    def __init__(self, name):
        self.name = name

# users.py
@Place.mixin
class UsersMixin(object):
    def get_users(self):
        return "users-of-{}".format(self.name)

# links.py
@Place.mixin
class LinksMixin(object):
    def get_links(self):
        return "links-of-{}".format(self.name)

p = Place('bangalore')
print(p.get_users())
print(p.get_links())

With this I was able to split the class into 3 files and now I have
flexibility of deciding which features enable from a config file.

What do you guys think of this approach?
Is this a good practice?
Are there any know flaws in this approach?
How did you solve that issue when you faced similar situation?

Anand

From kracethekingmaker at gmail.com  Thu Oct  9 08:00:37 2014
From: kracethekingmaker at gmail.com (kracekumar ramaraju)
Date: Thu, 9 Oct 2014 11:30:37 +0530
Subject: [BangPypers] Adding mixing at run-time
In-Reply-To: <CAC7wXFydyAOfx4mtE6QQjaoi6yNgPjiO7CUZ698peso3iAvJ=g@mail.gmail.com>
References: <CAC7wXFydyAOfx4mtE6QQjaoi6yNgPjiO7CUZ698peso3iAvJ=g@mail.gmail.com>
Message-ID: <CAO5c=mmjWPbvVAvCoXRQ4A3pGYJ2309+yWjoJqEUc497cKawhQ@mail.gmail.com>

On Wed, Oct 8, 2014 at 4:19 PM, Anand Chitipothu <anandology at gmail.com>
wrote:

> Hi,
>
> I'm working on a slightly large application and I'm trying to model it as a
> some kind of plugin architecture so that it modular and I can enable or
> take out features without lot of code changes.
>
> One of the issues I faced was that the wanted to add some methods to a
> class only when a feature/plugin is enabled.
>
> Here is a simplified version of what I have:
>
> class Place(Mixable):
>     def __init__(self, name):
>         self.name = name
>
>     def get_users(self):
>         return "users-of-{}".format(self.name)
>
>     def get_links(self):
>         return "links-of-{}".format(self.name)
>
> There are couple of issues with this.
>
> 1. The logic for computing users or links doesn't really belong to this
> file. I wanted to that in a separate module for modularity.
>
> 2. The Place class will become too large to manage over time.
>
> So, I came up with the following approach to address these issues.
>
> # place.py
>
> class Mixable(object):
>     """Magic class to allow adding mixins to the class at run-time.
>     """
>     @classmethod
>     def mixin(cls, mixin):
>         """Decorator to add a mixin to the class runtime.
>         """
>         cls.__bases__ = cls.__bases__ + (mixin,)
>
> class Place(Mixable):
>     def __init__(self, name):
>         self.name = name
>
> # users.py
> @Place.mixin
> class UsersMixin(object):
>     def get_users(self):
>         return "users-of-{}".format(self.name)
>
>
Is there any specific reason for using decorators ?



> # links.py
> @Place.mixin
> class LinksMixin(object):
>     def get_links(self):
>         return "links-of-{}".format(self.name)
>
> p = Place('bangalore')
> print(p.get_users())
> print(p.get_links())
>
>

I somehow feel this can lead to unexpected behaviour since Mixable classes
are added at various files.
This pattern looks like global variable argument (global variables are
bad). Say if Idecorate Foo with @Place.mixin by mistake, behaviour of the
Foo will be available in Place class and leads to side effect.

How about

#dispatcher.py
# import all the classes

def get_place_class():
      # Check for features
      for cls in classes:
           Place.__bases__ = Place.__bases__ + (cls,)
      return Place



> With this I was able to split the class into 3 files and now I have
> flexibility of deciding which features enable from a config file.
>
> What do you guys think of this approach?
>

My only concern base classes are added in different files and difficult to
remember.

Is this a good practice?
> Are there any know flaws in this approach?

How did you solve that issue when you faced similar situation?
>
>
Did I understand the problem correctly ?


> Anand
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>



-- 

*Thanks & Regardskracekumar"Talk is cheap, show me the code" -- Linus
Torvaldshttp://kracekumar.com <http://kracekumar.com>*

From superpulse.x at gmail.com  Thu Oct  9 09:51:15 2014
From: superpulse.x at gmail.com (venkatakrishnan g)
Date: Thu, 9 Oct 2014 13:21:15 +0530
Subject: [BangPypers] Adding mixing at run-time
In-Reply-To: <CAO5c=mmjWPbvVAvCoXRQ4A3pGYJ2309+yWjoJqEUc497cKawhQ@mail.gmail.com>
References: <CAC7wXFydyAOfx4mtE6QQjaoi6yNgPjiO7CUZ698peso3iAvJ=g@mail.gmail.com>
 <CAO5c=mmjWPbvVAvCoXRQ4A3pGYJ2309+yWjoJqEUc497cKawhQ@mail.gmail.com>
Message-ID: <CANVLBE8Uc8gSLca65_WqAuaV5esXao6K5PAy9SoHGR2gTcnYTQ@mail.gmail.com>

I think this is a very nice approach. I disagree that that you could
decorate a class as @Place.mixin by mistake,
In fact i think the decorator actually makes it absolutely clear its
purpose. However, the Place.mixin should return
the mixin class.

 @classmethod
    def mixin(cls, mixin):
        """Decorator to add a mixin to the class runtime.
        """
        cls.__bases__ = cls.__bases__ + (mixin,)

        return mixin


This:

1. Allows the class to be mixed-in into other classes if there's need for it
2. Class decorators should return classes, else LinksMixin evaluates to None



On 9 October 2014 11:30, kracekumar ramaraju <kracethekingmaker at gmail.com>
wrote:

> On Wed, Oct 8, 2014 at 4:19 PM, Anand Chitipothu <anandology at gmail.com>
> wrote:
>
> > Hi,
> >
> > I'm working on a slightly large application and I'm trying to model it
> as a
> > some kind of plugin architecture so that it modular and I can enable or
> > take out features without lot of code changes.
> >
> > One of the issues I faced was that the wanted to add some methods to a
> > class only when a feature/plugin is enabled.
> >
> > Here is a simplified version of what I have:
> >
> > class Place(Mixable):
> >     def __init__(self, name):
> >         self.name = name
> >
> >     def get_users(self):
> >         return "users-of-{}".format(self.name)
> >
> >     def get_links(self):
> >         return "links-of-{}".format(self.name)
> >
> > There are couple of issues with this.
> >
> > 1. The logic for computing users or links doesn't really belong to this
> > file. I wanted to that in a separate module for modularity.
> >
> > 2. The Place class will become too large to manage over time.
> >
> > So, I came up with the following approach to address these issues.
> >
> > # place.py
> >
> > class Mixable(object):
> >     """Magic class to allow adding mixins to the class at run-time.
> >     """
> >     @classmethod
> >     def mixin(cls, mixin):
> >         """Decorator to add a mixin to the class runtime.
> >         """
> >         cls.__bases__ = cls.__bases__ + (mixin,)
> >
> > class Place(Mixable):
> >     def __init__(self, name):
> >         self.name = name
> >
> > # users.py
> > @Place.mixin
> > class UsersMixin(object):
> >     def get_users(self):
> >         return "users-of-{}".format(self.name)
> >
> >
> Is there any specific reason for using decorators ?
>
>
>
> > # links.py
> > @Place.mixin
> > class LinksMixin(object):
> >     def get_links(self):
> >         return "links-of-{}".format(self.name)
> >
> > p = Place('bangalore')
> > print(p.get_users())
> > print(p.get_links())
> >
> >
>
> I somehow feel this can lead to unexpected behaviour since Mixable classes
> are added at various files.
> This pattern looks like global variable argument (global variables are
> bad). Say if Idecorate Foo with @Place.mixin by mistake, behaviour of the
> Foo will be available in Place class and leads to side effect.
>
> How about
>
> #dispatcher.py
> # import all the classes
>
> def get_place_class():
>       # Check for features
>       for cls in classes:
>            Place.__bases__ = Place.__bases__ + (cls,)
>       return Place
>
>
>
> > With this I was able to split the class into 3 files and now I have
> > flexibility of deciding which features enable from a config file.
> >
> > What do you guys think of this approach?
> >
>
> My only concern base classes are added in different files and difficult to
> remember.
>
> Is this a good practice?
> > Are there any know flaws in this approach?
>
> How did you solve that issue when you faced similar situation?
> >
> >
> Did I understand the problem correctly ?
>
>
> > Anand
> > _______________________________________________
> > BangPypers mailing list
> > BangPypers at python.org
> > https://mail.python.org/mailman/listinfo/bangpypers
> >
>
>
>
> --
>
> *Thanks & Regardskracekumar"Talk is cheap, show me the code" -- Linus
> Torvaldshttp://kracekumar.com <http://kracekumar.com>*
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>

From deepu.dtp at gmail.com  Thu Oct  9 12:56:25 2014
From: deepu.dtp at gmail.com (Deepu Thomas Philip)
Date: Thu, 9 Oct 2014 16:26:25 +0530
Subject: [BangPypers] Adding mixing at run-time
In-Reply-To: <CAC7wXFydyAOfx4mtE6QQjaoi6yNgPjiO7CUZ698peso3iAvJ=g@mail.gmail.com>
References: <CAC7wXFydyAOfx4mtE6QQjaoi6yNgPjiO7CUZ698peso3iAvJ=g@mail.gmail.com>
Message-ID: <CAHwa0+dhoiD-r8Pu9euFC=wwZG1-ns1fwVYH2ouB5ukhXOjsNg@mail.gmail.com>

On Wed, Oct 8, 2014 at 4:19 PM, Anand Chitipothu <anandology at gmail.com>
wrote:

> Hi,
>
> I'm working on a slightly large application and I'm trying to model it as a
> some kind of plugin architecture so that it modular and I can enable or
> take out features without lot of code changes.
>
> One of the issues I faced was that the wanted to add some methods to a
> class only when a feature/plugin is enabled.
>
> Here is a simplified version of what I have:
>
> class Place(Mixable):
>     def __init__(self, name):
>         self.name = name
>
>     def get_users(self):
>         return "users-of-{}".format(self.name)
>
>     def get_links(self):
>         return "links-of-{}".format(self.name)
>
> There are couple of issues with this.
>
> 1. The logic for computing users or links doesn't really belong to this
> file. I wanted to that in a separate module for modularity.
>
> 2. The Place class will become too large to manage over time.
>
> So, I came up with the following approach to address these issues.
>
> # place.py
>
> class Mixable(object):
>     """Magic class to allow adding mixins to the class at run-time.
>     """
>     @classmethod
>     def mixin(cls, mixin):
>         """Decorator to add a mixin to the class runtime.
>         """
>         cls.__bases__ = cls.__bases__ + (mixin,)
>
> class Place(Mixable):
>     def __init__(self, name):
>         self.name = name
>
> # users.py
> @Place.mixin
> class UsersMixin(object):
>     def get_users(self):
>         return "users-of-{}".format(self.name)
>
> # links.py
> @Place.mixin
> class LinksMixin(object):
>     def get_links(self):
>         return "links-of-{}".format(self.name)
>
p = Place('bangalore')
> print(p.get_users())
> print(p.get_links())
>
> With this I was able to split the class into 3 files and now I have
> flexibility of deciding which features enable from a config file.
>
>
While trying to remove logic that does not belong in the place module,
you introduced *place* into two other modules where it does not belong.

I did not understand the approach completely.
>From a config file how does one achieve plugin like architecture?

What do you guys think of this approach?
> Is this a good practice?
> Are there any know flaws in this approach?
>

Not sure if this is a flaw or expected behaviour

I could not get a Place + UserMixin instance and a Place + LinksMixin
instance to coexist
in the same scope at the same time.
Importing any of the mixins led to pollution of existing Place instances.

from place import Place
p = Place("bangalore")
from user import UserMixin
print p.get_links()                   # outputs 'links-of-bangalore'




> How did you solve that issue when you faced similar situation?


Any reason to not use a builder pattern or a factory method pattern?



>
>
Anand
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>

From anandology at gmail.com  Thu Oct  9 13:44:30 2014
From: anandology at gmail.com (Anand Chitipothu)
Date: Thu, 9 Oct 2014 17:14:30 +0530
Subject: [BangPypers] Adding mixing at run-time
In-Reply-To: <CAO5c=mmjWPbvVAvCoXRQ4A3pGYJ2309+yWjoJqEUc497cKawhQ@mail.gmail.com>
References: <CAC7wXFydyAOfx4mtE6QQjaoi6yNgPjiO7CUZ698peso3iAvJ=g@mail.gmail.com>
 <CAO5c=mmjWPbvVAvCoXRQ4A3pGYJ2309+yWjoJqEUc497cKawhQ@mail.gmail.com>
Message-ID: <CAC7wXFx790_6=d3aGTi0QK2WKBE6gE3ivq+9kJ_DUPjBJJS2OQ@mail.gmail.com>

On Thu, Oct 9, 2014 at 11:30 AM, kracekumar ramaraju <
kracethekingmaker at gmail.com> wrote:

> On Wed, Oct 8, 2014 at 4:19 PM, Anand Chitipothu <anandology at gmail.com>
> wrote:
>
> > Hi,
> >
> > I'm working on a slightly large application and I'm trying to model it
> as a
> > some kind of plugin architecture so that it modular and I can enable or
> > take out features without lot of code changes.
> >
> > One of the issues I faced was that the wanted to add some methods to a
> > class only when a feature/plugin is enabled.
> >
> > Here is a simplified version of what I have:
> >
> > class Place(Mixable):
> >     def __init__(self, name):
> >         self.name = name
> >
> >     def get_users(self):
> >         return "users-of-{}".format(self.name)
> >
> >     def get_links(self):
> >         return "links-of-{}".format(self.name)
> >
> > There are couple of issues with this.
> >
> > 1. The logic for computing users or links doesn't really belong to this
> > file. I wanted to that in a separate module for modularity.
> >
> > 2. The Place class will become too large to manage over time.
> >
> > So, I came up with the following approach to address these issues.
> >
> > # place.py
> >
> > class Mixable(object):
> >     """Magic class to allow adding mixins to the class at run-time.
> >     """
> >     @classmethod
> >     def mixin(cls, mixin):
> >         """Decorator to add a mixin to the class runtime.
> >         """
> >         cls.__bases__ = cls.__bases__ + (mixin,)
> >
> > class Place(Mixable):
> >     def __init__(self, name):
> >         self.name = name
> >
> > # users.py
> > @Place.mixin
> > class UsersMixin(object):
> >     def get_users(self):
> >         return "users-of-{}".format(self.name)
> >
> >
> Is there any specific reason for using decorators ?
>

Just because I felt that provides a nice API.

I would have used a more explicit approach like the following, but I liked
the decorators one better.

def setup_plugin():
    register_place_plugin(UsersMixin)

> # links.py
> > @Place.mixin
> > class LinksMixin(object):
> >     def get_links(self):
> >         return "links-of-{}".format(self.name)
> >
> > p = Place('bangalore')
> > print(p.get_users())
> > print(p.get_links())
>
>
> I somehow feel this can lead to unexpected behaviour since Mixable classes
> are added at various files.
>

Yes, it requires some discipline.


> This pattern looks like global variable argument (global variables are
> bad). Say if Idecorate Foo with @Place.mixin by mistake, behaviour of the
> Foo will be available in Place class and leads to side effect.
>

Well that is a compromise. Same as Flask vs. Django URL routing.


>
> How about
>
> #dispatcher.py
> # import all the classes
>
> def get_place_class():
>       # Check for features
>       for cls in classes:
>            Place.__bases__ = Place.__bases__ + (cls,)
>       return Place
>

That should be setup_place_class() and that should be called only once. But
the decorators approach makes calling it twice impossible.


> > With this I was able to split the class into 3 files and now I have
> > flexibility of deciding which features enable from a config file.
> >
> > What do you guys think of this approach?
> >
>
> My only concern base classes are added in different files and difficult to
> remember.
>

Yes, it will become difficult if not used with care, but I think it can be
used very elegantly if enough care is given.

What I really want is multiple people work on separate parts of the system
without having to touch the core code.


> Is this a good practice?
> > Are there any know flaws in this approach?
>
> How did you solve that issue when you faced similar situation?
> >
> >
> Did I understand the problem correctly ?
>

 I think so.

Anand

From rajalokan at gmail.com  Fri Oct 10 10:36:56 2014
From: rajalokan at gmail.com (Okan bhan)
Date: Fri, 10 Oct 2014 14:06:56 +0530
Subject: [BangPypers] Asynchronous method calls in python
Message-ID: <CAL9ehhpgK_e1rwjinVDzYT7o+G+LjhVRr+TNXH-PT=Z1L1k10A@mail.gmail.com>

Hi,

I'm working on an appengine + flask application which makes multiple
requests to third party APIs as part of one request. All of these are
independent.

So I was hoping what should be the best way to make these method calls
asynchronously. Whatever I know:

* *Using multi-threading in python*: I've heard not to try multithreaded in
your application itself it you are not sure. Rather rely on application
server.
* *Using something like Twisted*: Not an options as my stack doesn't allow
it.

Please suggest me what should be the best solution here?

Alok

From anandology at gmail.com  Fri Oct 10 10:50:00 2014
From: anandology at gmail.com (Anand Chitipothu)
Date: Fri, 10 Oct 2014 14:20:00 +0530
Subject: [BangPypers] Asynchronous method calls in python
In-Reply-To: <CAL9ehhpgK_e1rwjinVDzYT7o+G+LjhVRr+TNXH-PT=Z1L1k10A@mail.gmail.com>
References: <CAL9ehhpgK_e1rwjinVDzYT7o+G+LjhVRr+TNXH-PT=Z1L1k10A@mail.gmail.com>
Message-ID: <CAC7wXFycATKKLb0QXzavOzHfDg5LvD1OUfXL0N_i+VK7pFYmVg@mail.gmail.com>

On Fri, Oct 10, 2014 at 2:06 PM, Okan bhan <rajalokan at gmail.com> wrote:

> Hi,
>
> I'm working on an appengine + flask application which makes multiple
> requests to third party APIs as part of one request. All of these are
> independent.
>
> So I was hoping what should be the best way to make these method calls
> asynchronously. Whatever I know:
>
> * *Using multi-threading in python*: I've heard not to try multithreaded in
> your application itself it you are not sure. Rather rely on application
> server.
> * *Using something like Twisted*: Not an options as my stack doesn't allow
> it.
>
> Please suggest me what should be the best solution here?
>

Have you looked at app engine API for making async fetch requests?

https://cloud.google.com/appengine/docs/python/urlfetch/asynchronousrequests

Anand

From shyran at gmail.com  Fri Oct 10 10:43:53 2014
From: shyran at gmail.com (Kulkarni, Shreyas)
Date: Fri, 10 Oct 2014 14:13:53 +0530
Subject: [BangPypers] [JOBS] Looking for python/bash profiles
Message-ID: <A109DEE5-71BF-4BB3-A7DD-2D0071963BE4@gmail.com>

Hi guys,

We are looking for strong python and bash profiles in my team in Akamai Technologies. Here are a few criteria -

Good educational and professional background
Strong python design/development experience (this is not web-dev kind of a profile though) with good coding standards 
Should be comfortable and at home in Linux. Good hands on bash/shell-scripting experience will be a big plus. 
Good grasp of CS fundamentals like data structures, algorithms, networking is necessary. 
Knowledge of OOAD/OOP concepts will be a big plus. 
Good communication skills

It's a full time requirement, based out of Bangalore. Consultants please excuse. 

If anyone is interested, write to me with your profile. Please *DO NOT* reply-to-all. 

Thanks,
Shreyas Kulkarni

From vikramuk at gmail.com  Sat Oct 11 18:53:36 2014
From: vikramuk at gmail.com (Vikram Upadhya)
Date: Sat, 11 Oct 2014 22:23:36 +0530
Subject: [BangPypers] [JOBS] Looking for python/bash profiles
In-Reply-To: <A109DEE5-71BF-4BB3-A7DD-2D0071963BE4@gmail.com>
References: <A109DEE5-71BF-4BB3-A7DD-2D0071963BE4@gmail.com>
Message-ID: <CANwyay9q0tzfj80W25OkmVe+-Q3_XJ=gf3YjcMm7L8ay6ziffg@mail.gmail.com>

Hi Shreyas,
   Could you help conect me to Jobs with about 4 Years experience on
Scripting Languages.


With regards,
Vikram U
9916028682

On Fri, Oct 10, 2014 at 2:13 PM, Kulkarni, Shreyas <shyran at gmail.com> wrote:

> Hi guys,
>
> We are looking for strong python and bash profiles in my team in Akamai
> Technologies. Here are a few criteria -
>
> Good educational and professional background
> Strong python design/development experience (this is not web-dev kind of a
> profile though) with good coding standards
> Should be comfortable and at home in Linux. Good hands on
> bash/shell-scripting experience will be a big plus.
> Good grasp of CS fundamentals like data structures, algorithms, networking
> is necessary.
> Knowledge of OOAD/OOP concepts will be a big plus.
> Good communication skills
>
> It's a full time requirement, based out of Bangalore. Consultants please
> excuse.
>
> If anyone is interested, write to me with your profile. Please *DO NOT*
> reply-to-all.
>
> Thanks,
> Shreyas Kulkarni
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>



-- 
-Vikram

From jyothi.nadu at gmail.com  Mon Oct 13 06:43:46 2014
From: jyothi.nadu at gmail.com (Jyothi Naidu)
Date: Mon, 13 Oct 2014 10:13:46 +0530
Subject: [BangPypers] [JOBS] Looking for python/bash profiles
In-Reply-To: <CANwyay9q0tzfj80W25OkmVe+-Q3_XJ=gf3YjcMm7L8ay6ziffg@mail.gmail.com>
References: <A109DEE5-71BF-4BB3-A7DD-2D0071963BE4@gmail.com>
 <CANwyay9q0tzfj80W25OkmVe+-Q3_XJ=gf3YjcMm7L8ay6ziffg@mail.gmail.com>
Message-ID: <CABm=+UE5MPiWTzGCfzth8ffj87dKkHpCGbwJDR5bQCESYtA_Kg@mail.gmail.com>

Yes there are many more jobs available for 4 Years on PYTHON DEVELOPER

On Sat, Oct 11, 2014 at 10:23 PM, Vikram Upadhya <vikramuk at gmail.com> wrote:

> Hi Shreyas,
>    Could you help conect me to Jobs with about 4 Years experience on
> Scripting Languages.
>
>
> With regards,
> Vikram U
> 9916028682
>
> On Fri, Oct 10, 2014 at 2:13 PM, Kulkarni, Shreyas <shyran at gmail.com>
> wrote:
>
> > Hi guys,
> >
> > We are looking for strong python and bash profiles in my team in Akamai
> > Technologies. Here are a few criteria -
> >
> > Good educational and professional background
> > Strong python design/development experience (this is not web-dev kind of
> a
> > profile though) with good coding standards
> > Should be comfortable and at home in Linux. Good hands on
> > bash/shell-scripting experience will be a big plus.
> > Good grasp of CS fundamentals like data structures, algorithms,
> networking
> > is necessary.
> > Knowledge of OOAD/OOP concepts will be a big plus.
> > Good communication skills
> >
> > It's a full time requirement, based out of Bangalore. Consultants please
> > excuse.
> >
> > If anyone is interested, write to me with your profile. Please *DO NOT*
> > reply-to-all.
> >
> > Thanks,
> > Shreyas Kulkarni
> > _______________________________________________
> > BangPypers mailing list
> > BangPypers at python.org
> > https://mail.python.org/mailman/listinfo/bangpypers
> >
>
>
>
> --
> -Vikram
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>



-- 
Regards,
Jyothi Naidu
+91 8123459658

From er.kalra80 at gmail.com  Tue Oct 14 12:16:39 2014
From: er.kalra80 at gmail.com (neeraj kalra)
Date: Tue, 14 Oct 2014 15:46:39 +0530
Subject: [BangPypers] any guidance would be appreicated
Message-ID: <CA+hJg3Lm_ZeQh1i3AExpKnnJ5t5VL4EbSqy5t7XKt2FBstDv1Q@mail.gmail.com>

Sorry sending this mail without knowing all memebsr..I need assistance from
you and would appreciate if you provide any guidance to solve my issues.

1.  I am working on *customized mail client desktop app* to cater for
windows based at stage one and linux at a later stage.

2.  firstly i am not able to create a installer for windows... i used
CX_Freeze etc.. still there is no success to me ...Kindly suggest how to
create a installer for windows. My app has *many py* scripts and is also
using lot of dependencies dll.. and is based on tkinter etc

4.  Is it possible for me import address books of yahoo and gmail of the
user who enters his username and password (using python Tkinter) ?? Your
help will be appreciated.


thnx n regards
kalra

From kausikram at gmail.com  Tue Oct 14 13:53:10 2014
From: kausikram at gmail.com (kausikram krishnasayee)
Date: Tue, 14 Oct 2014 17:23:10 +0530
Subject: [BangPypers] [Job] OrangeScape is Looking for Passionate Pythonistas
Message-ID: <CAHYLgg01+z-wMp-0zDkpejAC8rudMCsEkAHf6VkSt7y8hx_K3A@mail.gmail.com>

Hi,

We at OrangeScape are hiring Python Developers who would join our team
in building some amazing cloud based products. OrangeScape was founded
in 2003 and is one among the Global 10 companies featured by Forrester
and Gartner in the Platform-as-a-service Category.

We are a bunch of dynamic geeks who work with cutting edge technology
in the cloud space.

The details of about the opening are available at:
http://grow.orangescape.com?utm_medium=email

If you are a passionate python developer and enjoy working with a team
of equally talented code geeks then you should totally apply. Do check
it out! And yes, we are known for taking good care of our employees :)

cheers,
Kausikram

From ppc.lists at gmail.com  Thu Oct 16 08:25:26 2014
From: ppc.lists at gmail.com (Pradip Caulagi)
Date: Thu, 16 Oct 2014 11:55:26 +0530
Subject: [BangPypers] Asynchronous method calls in python
In-Reply-To: <CAL9ehhpgK_e1rwjinVDzYT7o+G+LjhVRr+TNXH-PT=Z1L1k10A@mail.gmail.com>
References: <CAL9ehhpgK_e1rwjinVDzYT7o+G+LjhVRr+TNXH-PT=Z1L1k10A@mail.gmail.com>
Message-ID: <543F64D6.8090704@gmail.com>

On Friday 10 October 2014 02:06 PM, Okan bhan wrote:
> Hi,
>
> I'm working on an appengine + flask application which makes multiple
> requests to third party APIs as part of one request. All of these are
> independent.
>
> So I was hoping what should be the best way to make these method calls
> asynchronously. Whatever I know:

You could also use - 
https://docs.python.org/3/library/concurrent.futures.html.  It is ported 
to Python 2 in https://pypi.python.org/pypi/futures.

I tried concurrent.futures a bit - 
https://medium.com/@caulagi/python-concurrent-futures-1028b47db1cf

-- 
Pradip P Caulagi

From swvist at gmail.com  Thu Oct 16 08:39:41 2014
From: swvist at gmail.com (Vipin Nair)
Date: Thu, 16 Oct 2014 12:09:41 +0530
Subject: [BangPypers] Asynchronous method calls in python
In-Reply-To: <CAL9ehhpgK_e1rwjinVDzYT7o+G+LjhVRr+TNXH-PT=Z1L1k10A@mail.gmail.com>
References: <CAL9ehhpgK_e1rwjinVDzYT7o+G+LjhVRr+TNXH-PT=Z1L1k10A@mail.gmail.com>
Message-ID: <CAM5pN3YYdUGg9DFYxj_P87rEgrpvOG5AR8BMOV73z3Jzx0dmBA@mail.gmail.com>

> I'm working on an appengine + flask application which makes multiple
> requests to third party APIs as part of one request. All of these are
> independent.
>
> So I was hoping what should be the best way to make these method calls
> asynchronously. Whatever I know:


I have used grequests[1] in the past to do something similar.

[1]: https://github.com/kennethreitz/grequests


-- 
Regards,
Vipin

From rajalokan at gmail.com  Thu Oct 16 14:50:29 2014
From: rajalokan at gmail.com (Okan bhan)
Date: Thu, 16 Oct 2014 18:20:29 +0530
Subject: [BangPypers] Asynchronous method calls in python
Message-ID: <CAL9ehhomdb0y1uipp+OgZCRNSASb5J7bC4nmC3Jc-+5mPBtfOQ@mail.gmail.com>

>
> Thanks everyone for answers. I'm looking into these options. Thanks again.
>

Regards
Alok

From tk446 at snu.edu.in  Wed Oct 22 13:41:19 2014
From: tk446 at snu.edu.in (Tarun Kumar)
Date: Wed, 22 Oct 2014 17:11:19 +0530
Subject: [BangPypers] Micropython without pyboard
Message-ID: <CAGrKnhGsnyvbceuX2ycjmCaSt=Qibagu-a9fFZXk1YQYAJQh9A@mail.gmail.com>

Hello all
Greetings of diwali..!!

I want to use micropython without pyboard. Instead of pyboard I am using "
stm32f4" which is very similar to pyboard, the only difference is pyboard
is pre-installed with micropython. And I want to install it on stm32f4
board.
I have source code of micropython. But what package is required to port it
on hardware.



-- 

-Tarun Kumar
Shiv Nadar University
----------------------------------------

From joepaulp at gmail.com  Thu Oct 23 08:55:56 2014
From: joepaulp at gmail.com (Joe Paul)
Date: Thu, 23 Oct 2014 08:55:56 +0200
Subject: [BangPypers] From: Joe Paul
Message-ID: <kvbqpcpxgven8cvkacykeyuv.14140473567153@email.android.com>


Hiya bangpypers


http://mylaughablenews.com/mouth.php?death=3egb5s0hf6bbvpcvkdkd



joepaulp at gmail.com

From rajalokan at gmail.com  Sun Oct 26 06:21:00 2014
From: rajalokan at gmail.com (Okan bhan)
Date: Sun, 26 Oct 2014 10:51:00 +0530
Subject: [BangPypers] Evaluating a string against mapping in python.
Message-ID: <CAL9ehhoUDAs+uVbo0GWJteher8KzLW4LQsivtJOhorpfHVNG3A@mail.gmail.com>

Hello everyone,

Hope you all celebrated festival of Diwali with your loved ones. Wishes
from my side to each one of you.

I'm facing issue in understanding python's 'eval' function's behaviour.
I've no previous deep knowledge of using 'eval' except that "it is used to
evaluate a string just like on python prompt". While working on a feature
on pytest, I encountered usage of eval against a map.

For a very simple case, I wanted to check if a string exists within a list.
Very simple
>>>   'foo' in list_foo.

But string 'foo' can contain expression (like 'foo and bar'). To check
this, I see they have used something like

>>> eval('foo and bar', {}, mapping).

A simple implementation of this is:

class SimpleMapping:
  def __init__(self, items):
    self._items = items

  def __getitems__(self, subitem):
    print('*' * 20)
    for item in self._items:
      if subitem in item:
        return True
    return False

Playing around against it for a bit.
>>>  mapping = SimpleMapping(set(['aaa', 'bbb', 'ccc']))
>>>  eval('ppp', {}, mapping)
        ********************
        False
>>>  eval('aa', {}, mapping)
        ********************
        True
>>>  eval('xxx and aaa', {}, mapping)
        ********************
        False
>>>  eval('xxx or aaa', {}, mapping)
        ********************
        ********************
        True

Struggled in beginning but now they all seem obvious to me. Tricky is:

>>>  eval('5.6', {}, mapping)
        5.6
>>>  eval('aa.a', {}, mapping)
        AttributeError: 'bool' object has no attribute 'a'

My doubts are:
a. Why it didn't run for numeric 5.6? Also why is dot separated '5.6' any
different to 'aa.a'? I looked around on eval documentation and examples but
couldn't find use of eval with a mapping.

b. I see many blogs suggesting to refrain from using eval unless absolutely
needed. Is this one use case we must use it? Do we have any better way to
evaluate this?

c. If indeed, I have to evaluate a string containing dots, how to do in the
above scenario?

Would appreciate any pointers or more clarity on this.

Thanks & Regards
Alok

From noufal at nibrahim.net.in  Sun Oct 26 12:58:31 2014
From: noufal at nibrahim.net.in (Noufal Ibrahim KV)
Date: Sun, 26 Oct 2014 17:28:31 +0530
Subject: [BangPypers] Evaluating a string against mapping in python.
In-Reply-To: <CAL9ehhoUDAs+uVbo0GWJteher8KzLW4LQsivtJOhorpfHVNG3A@mail.gmail.com>
 (Okan bhan's message of "Sun, 26 Oct 2014 10:51:00 +0530")
References: <CAL9ehhoUDAs+uVbo0GWJteher8KzLW4LQsivtJOhorpfHVNG3A@mail.gmail.com>
Message-ID: <87k33njb4o.fsf@nibrahim.net.in>

On Sun, Oct 26 2014, Okan bhan wrote:


[...]

> A simple implementation of this is:
>
> class SimpleMapping:
>   def __init__(self, items):
>     self._items = items
>
>   def __getitems__(self, subitem):
>     print('*' * 20)
>     for item in self._items:
>       if subitem in item:
>         return True
>     return False                    

This is broken in two ways
1. The magic method is __getitem__ (not __getitems__). I'm assuming it's
   a typo otherwise, the rest of your code will not work even as you've
   mentioned. 
2. A mapping object is similar to a dictionary. It should
   return the actual object if you try to access it. Not a boolean True
   or False. 

The mapping objects given are specifications of the locals and globals
in which you will evaluate your string. Consult help("eval") for more
information.

    eval(source[, globals[, locals]]) -> value

> Playing around against it for a bit.
>>>>  mapping = SimpleMapping(set(['aaa', 'bbb', 'ccc']))
>>>>  eval('ppp', {}, mapping)
>         ********************
>         False
>>>>  eval('aa', {}, mapping)
>         ********************
>         True
>>>>  eval('xxx and aaa', {}, mapping)
>         ********************
>         False
>>>>  eval('xxx or aaa', {}, mapping)
>         ********************
>         ********************
>         True
>
> Struggled in beginning but now they all seem obvious to me. Tricky is:

Look at my comment above. Your Mapping object is flawed and all these
responses are quite wrong.

>
>>>>  eval('5.6', {}, mapping)
>         5.6

I'm not sure how this will work. In my case, I see this. 

>>> mapping = SimpleMapping(set(['aaa', 'bbb', 'ccc']))
>>> eval('5.6', {}, mapping)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: locals must be a mapping
>>> 


>>>>  eval('aa.a', {}, mapping)
>         AttributeError: 'bool' object has no attribute 'a'
>

> My doubts are:
> a. Why it didn't run for numeric 5.6? Also why is dot separated '5.6' any
> different to 'aa.a'? I looked around on eval documentation and examples but
> couldn't find use of eval with a mapping.

5.6 is not an attribute access. 5.6 is is a floating point number. aa.a
is an attribute access. It will first return False for `aa` since there
is no such key and your code returns False and then try to access `a` in
the Boolean which, predictably, fails. 

> b. I see many blogs suggesting to refrain from using eval unless
> absolutely needed. Is this one use case we must use it? Do we have any
> better way to evaluate this?

I'm not sure what exactly you want to do. Can you explain again?

> c. If indeed, I have to evaluate a string containing dots, how to do
> in the above scenario?

The object whose attribute you're trying to access should be there in
the locals or globals and then should have an attribute with the given
name. It will work then.
[...]


-- 
Cordially,
Noufal
http://nibrahim.net.in

From murali.malladi at gmail.com  Mon Oct 27 12:52:40 2014
From: murali.malladi at gmail.com (Murali Krishna)
Date: Mon, 27 Oct 2014 17:22:40 +0530
Subject: [BangPypers] [JOBS] - Opportunity in Test Framework Development &
 Test Automation team at Nutanix Bangalore
Message-ID: <CALC8wS0KAiTNnfDr-FtJ6R4e_j4WVMFgVxGJaFVSYynKSc+NyQ@mail.gmail.com>

Hi All,

We have multiple positions open for highly skilled Python Programmers
(of-course with relevant background), for our new team at Nutanix,
Bangalore (http://www.nutanix.com)
Please note that the team is being setup newly, so our humble request to
engineers is to apply only if they consider their level in Python and Test
frameworks development to be "Intermediate to Expert".

Job Description: https://hire.jobvite.com/j?cj=oaBAZfw4&s=Personal_Message

Apply Online: https://hire.jobvite.com/j?aj=oaBAZfw4&s=Personal_Message

Note that the Lead position is already closed. All open positions are
Individual Contributor roles and experience range between 3-10 years.

Thanks,
Murali Malladi
https://in.linkedin.com/in/muralimalladi

From rajalokan at gmail.com  Mon Oct 27 16:47:28 2014
From: rajalokan at gmail.com (Okan bhan)
Date: Mon, 27 Oct 2014 21:17:28 +0530
Subject: [BangPypers] BangPypers Digest, Vol 86, Issue 16
In-Reply-To: <mailman.11.1414407602.842.bangpypers@python.org>
References: <mailman.11.1414407602.842.bangpypers@python.org>
Message-ID: <CAL9ehhrtn8JJ31zQhzhgOeS31Rk66Tedf+95JnPfjPfrAcL9gg@mail.gmail.com>

Hi Noufal,

Thanks for responding and helping me explaining these. I see lots of my
doubts are clear, except last (c). My explanations are inline.

> A simple implementation of this is:
> >
> > class SimpleMapping:
> >   def __init__(self, items):
> >     self._items = items
> >
> >   def __getitems__(self, subitem):
> >     print('*' * 20)
> >     for item in self._items:
> >       if subitem in item:
> >         return True
> >     return False
>
> This is broken in two ways
> 1. The magic method is __getitem__ (not __getitems__). I'm assuming it's
>    a typo otherwise, the rest of your code will not work even as you've
>    mentioned.
>
Yes. Indeed it should be __getitem__. It was typo while manually typing in
gmail.


> 2. A mapping object is similar to a dictionary. It should
>    return the actual object if you try to access it. Not a boolean True
>    or False.
>
Agree with you. Ideally it should have returned object and I can test by
`if obj` or `if not obj`. Lets assume for now I want to continue with this.

>
> The mapping objects given are specifications of the locals and globals
> in which you will evaluate your string. Consult help("eval") for more
> information.
>
>     eval(source[, globals[, locals]]) -> value
>
Makes sense. So essentially I'm trying to evaluate and expression ('foo' or
'foo and bar') against a local mapping. Not fully confident but I can see
the use of locals & globals here.


> Look at my comment above. Your Mapping object is flawed and all these
> responses are quite wrong.
>

Yes. Sorry for the typo. Without typo these will be the expected answers.

>
> >
> >>>>  eval('5.6', {}, mapping)
> >         5.6
>
> I'm not sure how this will work. In my case, I see this.
>
> >>> mapping = SimpleMapping(set(['aaa', 'bbb', 'ccc']))
> >>> eval('5.6', {}, mapping)
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> TypeError: locals must be a mapping
> >>>
>
> That is strange, I'm still getting 5.6 as result. I tried on different
python versions as well.

>
> >>>>  eval('aa.a', {}, mapping)
> >         AttributeError: 'bool' object has no attribute 'a'
> >
>
> > My doubts are:
> > a. Why it didn't run for numeric 5.6? Also why is dot separated '5.6' any
> > different to 'aa.a'? I looked around on eval documentation and examples
> but
> > couldn't find use of eval with a mapping.
>
> 5.6 is not an attribute access. 5.6 is is a floating point number. aa.a
> is an attribute access. It will first return False for `aa` since there
> is no such key and your code returns False and then try to access `a` in
> the Boolean which, predictably, fails.
>
> Big thanks for this. Let me explain what, I understood here.
Lets say statement we want to evaluate is `eval(expression)`. Python starts
checking 'expression' against each datatype starting from int -> float ->
str. For all native datatypes, it will return corresponding result. Finally
if it doesn't matches any of native types, tries to access against
mapping(or any other object in local or global scope).

Which is the reason,
>> type(eval('5.6'))   is float
>> type(eval("'5.6'") is str  (expression is under double quotes).

For the case of eval('aa.a'), it first tries to match 'aa'. This is not any
native type so goes to check in mapping and finds it True. Then tries to
find attribute 'a' of returned type (a boolean). Hence boolean object has
no attribute 'a'.


> > b. I see many blogs suggesting to refrain from using eval unless
> > absolutely needed. Is this one use case we must use it? Do we have any
> > better way to evaluate this?
>
> I'm not sure what exactly you want to do. Can you explain again?
>
I came across blog posts suggesting not to use eval mostly as it can lead
to un-secure code. So wanted to check should I put efforts in solving this
with 'eval' or not. Not an option now. I will explain my problem in next
question.

>
> > c. If indeed, I have to evaluate a string containing dots, how to do
> > in the above scenario?
>
> The object whose attribute you're trying to access should be there in
> the locals or globals and then should have an attribute with the given
> name. It will work then.
> [...]
>
yes. If my above observation is correct, this is clear to me. I will try to
explain my problem:

I have a list of strings ( say ['aaa', 'bbb', '4.5-'] ) and I want to check
if an expression (say 'aa') is a substring of any of this item.

Simply:   all([ item for item in ['aaa', 'bbb', '4.5-'] if 'aa' in item])
  ==> gives True as 'aa' is a substring of 'aaa'.

But my expression can be a logical expression like 'aa or bb',  'aa and
bbb', 'aaa and 4.5' etc.

This works in my above implementation. If we assume mapping object from
above. Writing it again here for ease.

> class SimpleMapping:
>   def __init__(self, items):
>     self._items = items
>
>   def __getitem__(self, subitem):
>     for item in self._items:
>       if subitem in item:
>         return True
>     return False

>>> mapping = SimpleMapping(set(['aaa', 'bbb', '4.5-']))

>>>   eval('aa and bb', {}, mapping)
True                                                          # since both
are substring
>>>  eval('aa and bbb', {}, mapping)
True                                                          # again since
both are substring
>>>  eval('aa and bbbb', {}, mapping)
False                                                         # 'bbbb'
fails.

So till now it works fine for my case. But in case if I want to check for
'4.5' in this.

>>> eval('aaaa or bbbb or 4.5')
4.5                                                           # Fails for
'aaaa', fails for 'bbbb' but evaluates '4.5' as 4.5. Something I don't
want. It should be
             checking 4.5 against mapping and I want a boolean True here.

If I am unclear, I will repeat my problem again.

Problem:   How can I evaluate a logical expression, in python where
expression contains a dot ('.').

Analysis:    First thing strike in my mind is to use eval but that fails on
expression with a dot. My tries are:

*Try A:*  I was thinking something like, transform '.' to '#' (or anything
else). For eg.

'aaaa or bbbb or 4.5' becomes 'aaaa or bbbb or 4#5'.
Now if eval('4#5') goes to check inside our mapping we are good. We can
transform back and evaluate. But sadly eval('4#5') gives 4. Tried with many
characters, any hits here?

*Try B:* Other option is extracting operators out of string ( by list
comprehension or using regular expression) and operator on these string
components.
Is there any direct way to get logical operators from string. I found (c for
c in s if c in '+-/*()_') to get mathematical operators.

I will try this option tonight.

Sorry for long reply and redundant answer but I wanted to be clear. If I
was able to explain properly can you suggest anything here?

Thanks & Regard
Alok

From noufal at nibrahim.net.in  Mon Oct 27 16:58:58 2014
From: noufal at nibrahim.net.in (Noufal Ibrahim KV)
Date: Mon, 27 Oct 2014 21:28:58 +0530
Subject: [BangPypers] BangPypers Digest, Vol 86, Issue 16
In-Reply-To: <CAL9ehhrtn8JJ31zQhzhgOeS31Rk66Tedf+95JnPfjPfrAcL9gg@mail.gmail.com>
 (Okan bhan's message of "Mon, 27 Oct 2014 21:17:28 +0530")
References: <mailman.11.1414407602.842.bangpypers@python.org>
 <CAL9ehhrtn8JJ31zQhzhgOeS31Rk66Tedf+95JnPfjPfrAcL9gg@mail.gmail.com>
Message-ID: <877fzlfqrh.fsf@nibrahim.net.in>




On Mon, Oct 27 2014, Okan bhan wrote:

> Hi Noufal,
>
> Thanks for responding and helping me explaining these. I see lots of my
> doubts are clear, except last (c). My explanations are inline.
>
>> A simple implementation of this is:
>> >
>> > class SimpleMapping:
>> >   def __init__(self, items):
>> >     self._items = items
>> >
>> >   def __getitems__(self, subitem):
>> >     print('*' * 20)
>> >     for item in self._items:
>> >       if subitem in item:
>> >         return True
>> >     return False
>>
>> This is broken in two ways
>> 1. The magic method is __getitem__ (not __getitems__). I'm assuming it's
>>    a typo otherwise, the rest of your code will not work even as you've
>>    mentioned.
>>
> Yes. Indeed it should be __getitem__. It was typo while manually typing in
> gmail.
>
>
>> 2. A mapping object is similar to a dictionary. It should
>>    return the actual object if you try to access it. Not a boolean True
>>    or False.
>>
> Agree with you. Ideally it should have returned object and I can test by
> `if obj` or `if not obj`. Lets assume for now I want to continue with this.
>
>>
>> The mapping objects given are specifications of the locals and globals
>> in which you will evaluate your string. Consult help("eval") for more
>> information.
>>
>>     eval(source[, globals[, locals]]) -> value
>>
> Makes sense. So essentially I'm trying to evaluate and expression ('foo' or
> 'foo and bar') against a local mapping. Not fully confident but I can see
> the use of locals & globals here.
>
>
>> Look at my comment above. Your Mapping object is flawed and all these
>> responses are quite wrong.
>>
>
> Yes. Sorry for the typo. Without typo these will be the expected answers.
>
>>
>> >
>> >>>>  eval('5.6', {}, mapping)
>> >         5.6
>>
>> I'm not sure how this will work. In my case, I see this.
>>
>> >>> mapping = SimpleMapping(set(['aaa', 'bbb', 'ccc']))
>> >>> eval('5.6', {}, mapping)
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in <module>
>> TypeError: locals must be a mapping
>> >>>
>>
>> That is strange, I'm still getting 5.6 as result. I tried on different
> python versions as well.
>
>>
>> >>>>  eval('aa.a', {}, mapping)
>> >         AttributeError: 'bool' object has no attribute 'a'
>> >
>>
>> > My doubts are:
>> > a. Why it didn't run for numeric 5.6? Also why is dot separated '5.6' any
>> > different to 'aa.a'? I looked around on eval documentation and examples
>> but
>> > couldn't find use of eval with a mapping.
>>
>> 5.6 is not an attribute access. 5.6 is is a floating point number. aa.a
>> is an attribute access. It will first return False for `aa` since there
>> is no such key and your code returns False and then try to access `a` in
>> the Boolean which, predictably, fails.
>>
>> Big thanks for this. Let me explain what, I understood here.
> Lets say statement we want to evaluate is `eval(expression)`. Python starts
> checking 'expression' against each datatype starting from int -> float ->
> str. For all native datatypes, it will return corresponding result. Finally
> if it doesn't matches any of native types, tries to access against
> mapping(or any other object in local or global scope).
>
> Which is the reason,
>>> type(eval('5.6'))   is float
>>> type(eval("'5.6'") is str  (expression is under double quotes).
>
> For the case of eval('aa.a'), it first tries to match 'aa'. This is not any
> native type so goes to check in mapping and finds it True. Then tries to
> find attribute 'a' of returned type (a boolean). Hence boolean object has
> no attribute 'a'.
>
>
>> > b. I see many blogs suggesting to refrain from using eval unless
>> > absolutely needed. Is this one use case we must use it? Do we have any
>> > better way to evaluate this?
>>
>> I'm not sure what exactly you want to do. Can you explain again?
>>
> I came across blog posts suggesting not to use eval mostly as it can lead
> to un-secure code. So wanted to check should I put efforts in solving this
> with 'eval' or not. Not an option now. I will explain my problem in next
> question.
>
>>
>> > c. If indeed, I have to evaluate a string containing dots, how to do
>> > in the above scenario?
>>
>> The object whose attribute you're trying to access should be there in
>> the locals or globals and then should have an attribute with the given
>> name. It will work then.
>> [...]
>>
> yes. If my above observation is correct, this is clear to me. I will try to
> explain my problem:
>
> I have a list of strings ( say ['aaa', 'bbb', '4.5-'] ) and I want to check
> if an expression (say 'aa') is a substring of any of this item.
>
> Simply:   all([ item for item in ['aaa', 'bbb', '4.5-'] if 'aa' in item])
>   ==> gives True as 'aa' is a substring of 'aaa'.
>
> But my expression can be a logical expression like 'aa or bb',  'aa and
> bbb', 'aaa and 4.5' etc.
>
> This works in my above implementation. If we assume mapping object from
> above. Writing it again here for ease.
>
>> class SimpleMapping:
>>   def __init__(self, items):
>>     self._items = items
>>
>>   def __getitem__(self, subitem):
>>     for item in self._items:
>>       if subitem in item:
>>         return True
>>     return False
>
>>>> mapping = SimpleMapping(set(['aaa', 'bbb', '4.5-']))
>
>>>>   eval('aa and bb', {}, mapping)
> True                                                          # since both
> are substring
>>>>  eval('aa and bbb', {}, mapping)
> True                                                          # again since
> both are substring
>>>>  eval('aa and bbbb', {}, mapping)
> False                                                         # 'bbbb'
> fails.
>
> So till now it works fine for my case. But in case if I want to check for
> '4.5' in this.
>
>>>> eval('aaaa or bbbb or 4.5')
> 4.5                                                           # Fails for
> 'aaaa', fails for 'bbbb' but evaluates '4.5' as 4.5. Something I don't
> want. It should be
>              checking 4.5 against mapping and I want a boolean True here.
>
> If I am unclear, I will repeat my problem again.
>
> Problem:   How can I evaluate a logical expression, in python where
> expression contains a dot ('.').
>
> Analysis:    First thing strike in my mind is to use eval but that fails on
> expression with a dot. My tries are:
>
> *Try A:*  I was thinking something like, transform '.' to '#' (or anything
> else). For eg.
>
> 'aaaa or bbbb or 4.5' becomes 'aaaa or bbbb or 4#5'.
> Now if eval('4#5') goes to check inside our mapping we are good. We can
> transform back and evaluate. But sadly eval('4#5') gives 4. Tried with many
> characters, any hits here?
>
> *Try B:* Other option is extracting operators out of string ( by list
> comprehension or using regular expression) and operator on these string
> components.
> Is there any direct way to get logical operators from string. I found (c for
> c in s if c in '+-/*()_') to get mathematical operators.
>
> I will try this option tonight.
>
> Sorry for long reply and redundant answer but I wanted to be clear. If I
> was able to explain properly can you suggest anything here?
>
> Thanks & Regard
> Alok
> _______________________________________________
> BangPypers mailing list
> BangPypers at python.org
> https://mail.python.org/mailman/listinfo/bangpypers
>

-- 
Cordially,
Noufal
http://nibrahim.net.in

From noufal at nibrahim.net.in  Mon Oct 27 17:38:13 2014
From: noufal at nibrahim.net.in (Noufal Ibrahim KV)
Date: Mon, 27 Oct 2014 22:08:13 +0530
Subject: [BangPypers] eval (was:  BangPypers Digest, Vol 86, Issue 16)
In-Reply-To: <CAL9ehhrtn8JJ31zQhzhgOeS31Rk66Tedf+95JnPfjPfrAcL9gg@mail.gmail.com>
 (Okan bhan's message of "Mon, 27 Oct 2014 21:17:28 +0530")
References: <mailman.11.1414407602.842.bangpypers@python.org>
 <CAL9ehhrtn8JJ31zQhzhgOeS31Rk66Tedf+95JnPfjPfrAcL9gg@mail.gmail.com>
Message-ID: <87a94headm.fsf_-_@nibrahim.net.in>


Please ignore my earlier reply to your email. I hit send by accident.

Please edit the subject line when you're replying to a digest.

On Mon, Oct 27 2014, Okan bhan wrote:


[...]

>> 2. A mapping object is similar to a dictionary. It should
>>    return the actual object if you try to access it. Not a boolean True
>>    or False.
>>
> Agree with you. Ideally it should have returned object and I can test
> by `if obj` or `if not obj`. Lets assume for now I want to continue
> with this.

I didn't understand what you mean by this. What are you attempting to
test with the `if` statements? And what do you want to continue with?

>> The mapping objects given are specifications of the locals and globals
>> in which you will evaluate your string. Consult help("eval") for more
>> information.
>>
>>     eval(source[, globals[, locals]]) -> value
>>
> Makes sense. So essentially I'm trying to evaluate and expression
> ('foo' or 'foo and bar') against a local mapping. Not fully confident
> but I can see the use of locals & globals here.

Every statement needs an evaluation context. Suppose I ask what the
result of the statement `x+2` is, you need a context which provides the
value of `x` to be able to answer meaningfully.

Python has two such contexts. First is the local context which is inside
the function and the second is the global context which is at the module
level.

Without these, the source referred to above cannot be `eval`uated.

[...]

> That is strange, I'm still getting 5.6 as result. I tried on different
> python versions as well.

What version of Python are you using?


[...]

>> 5.6 is not an attribute access. 5.6 is is a floating point number. aa.a
>> is an attribute access. It will first return False for `aa` since there
>> is no such key and your code returns False and then try to access `a` in
>> the Boolean which, predictably, fails.
>>
> Big thanks for this. Let me explain what, I understood here.  Lets say
> statement we want to evaluate is `eval(expression)`. Python starts
> checking 'expression' against each datatype starting from int -> float
> -> str. For all native datatypes, it will return corresponding
> result. Finally if it doesn't matches any of native types, tries to
> access against mapping(or any other object in local or global scope).

This is a theory that explains the observations but I can't fully
endorse your wording. Statements like "Python starts *checking*
'expression' against each *datatype* *starting* from int -> float ->
str" is too slipshod for my tastes. 

Expressions (and I use this to mean the expr_stmt in the grammar[1]),
have to be evaluated. A variable is an expression and it is evaluated by
a symbol lookup. It is looked up first in the local and on failure, in
the global context.

> Which is the reason,
>>> type(eval('5.6'))   is float
>>> type(eval("'5.6'") is str  (expression is under double quotes).
>
> For the case of eval('aa.a'), it first tries to match 'aa'. This is not any
> native type so goes to check in mapping and finds it True. Then tries to
> find attribute 'a' of returned type (a boolean). Hence boolean object has
> no attribute 'a'.

More or less but it doesn't try to "match" `aa`. The expression first
tokenised. You can see this. 

1,0-1,2:        NAME    'aa'
1,2-1,3:        OP      '.'
1,3-1,4:        NAME    'a'
2,0-2,0:        ENDMARKER       ''

This will get reduced into an expression and then be evaluated. The `aa`
is looked up and then the semantics indicate that an attribute lookup
should take place. 

[...]

> I came across blog posts suggesting not to use eval mostly as it can lead
> to un-secure code. So wanted to check should I put efforts in solving this
> with 'eval' or not. Not an option now. I will explain my problem in next
> question.

evaling code which you have complete control over and which you generate
is as safe as general code (although trickier to debug). If there's some
tainted data in the string that you eval, the effects might be
unpredictable.


[...]

> yes. If my above observation is correct, this is clear to me. I will try to
> explain my problem:
>
> I have a list of strings ( say ['aaa', 'bbb', '4.5-'] ) and I want to check
> if an expression (say 'aa') is a substring of any of this item.
>
> Simply:   all([ item for item in ['aaa', 'bbb', '4.5-'] if 'aa' in item])
>   ==> gives True as 'aa' is a substring of 'aaa'.

Fair enough. That makes sense.

> But my expression can be a logical expression like 'aa or bb',  'aa and
> bbb', 'aaa and 4.5' etc.

I'd do this by creating a predicate function
e.g.

  def test(x):
    'aa' in x or 'bb' in x

and then

  all(item for item in ['aaa', 'bbb', '4.5-'] if test(item))


> This works in my above implementation. If we assume mapping object from
> above. Writing it again here for ease.
>
>> class SimpleMapping:
>>   def __init__(self, items):
>>     self._items = items
>>
>>   def __getitem__(self, subitem):
>>     for item in self._items:
>>       if subitem in item:
>>         return True
>>     return False
>
>>>> mapping = SimpleMapping(set(['aaa', 'bbb', '4.5-']))
>
>>>>   eval('aa and bb', {}, mapping)
> True                                                          # since both
> are substring
>>>>  eval('aa and bbb', {}, mapping)
> True                                                          # again since
> both are substring
>>>>  eval('aa and bbbb', {}, mapping)
> False                                                         # 'bbbb'
> fails.

Okay. I think I see what you're trying to do. You're creating something
like a mapping which contains these strings and then evaling a boolean
expression which just does a lookup. 

This works but it contorted and hard to read/maintain. I wouldn't do it
this way. I'd use a predicate.

> So till now it works fine for my case. But in case if I want to check for
> '4.5' in this.
>
>>>> eval('aaaa or bbbb or 4.5')
> 4.5                                                           # Fails for
> 'aaaa', fails for 'bbbb' but evaluates '4.5' as 4.5. Something I don't
> want. It should be
>              checking 4.5 against mapping and I want a boolean True here.
>
> If I am unclear, I will repeat my problem again.

Eval is not suited for the problem. I suppose you could do some quoting
magic to take care of this but, like I said, it just makes it more and
more contorted.

When you eval something, it's treated as a piece of python code. You
however want to check for strings.


> Problem:   How can I evaluate a logical expression, in python where
> expression contains a dot ('.').

This is not a complete statement. 

   file1.opened and file2.opened

is a logical expression which has



[...]

> Sorry for long reply and redundant answer but I wanted to be clear. If I
> was able to explain properly can you suggest anything here?

[...]

I'd use the predicate approach.

Footnotes: 
[1]  https://docs.python.org/2/reference/grammar.html

-- 
Cordially,
Noufal
http://nibrahim.net.in

From arvindkhadri at gmail.com  Wed Oct 29 11:26:27 2014
From: arvindkhadri at gmail.com (Arvind K)
Date: Wed, 29 Oct 2014 15:56:27 +0530
Subject: [BangPypers] [JOBS] Servelots is hiring a backend stack web
	developer
Message-ID: <CAAyXcGDqi98k60D0jEgrutFRpzGgvmDAACPsa0iPwQt0BoDuow@mail.gmail.com>

Hi, Servelots[0] is looking for a developer with 2-3 years of experience in
building web applications using python.

Please spread the word.

[0]: http://servelots.com

From tanuj at toptalent.in  Thu Oct 30 12:11:21 2014
From: tanuj at toptalent.in (Tanuj Deshpande)
Date: Thu, 30 Oct 2014 16:41:21 +0530
Subject: [BangPypers] (no subject)
Message-ID: <CAN2SD9JaqZ4V3hucu214Ax_C3z0FurT8Kf7BiNxBpZBSYQx7pg@mail.gmail.com>

Hi,

Gigstart, Gurgaon is looking for Python Developer. If interested, Please
follow the link below.
https://www.toptalent.in/job/3476/python-developer-intern-new-delhi-india/

Thanks,
Tanuj.