[Tutor] reinitializing namespace

[Kent Johnson]

I'm still not sure why there is a problem. How are you running the scripts from the interactive 
session? If you are importing the script, its variables will be in its own namespace. If you are 
creating variables interactively yourself, your best bet is probably to just restart the 
interpreter. (If you use IDLE you can reset the interpreter from a menu without having to quit IDLE.)

It sounds like you are just coming to Python from Matlab and you are anticipating the same kinds of 
problems in Python as you are used to in Matlab. Have you actually worked with a script in the 
interpreter? Can you show us a sample interaction? Are you having a problem with name collisions in 
Python?

It really sounds to me like this is either a non-issue or that you should just restart the 
interpreter when you need a clean slate.

Here is an example of isolation between modules and reloading.

Suppose A1.py and A2.py both contain this code (except A2 prints 'A2.a ='):

## A1.py
a = 0

def bumpA():
   global a
   a += 1
   print 'A1.a =', a


I can use these modules interactively like this:
  >>> import A1
  >>> A1.bumpA()
A1.a = 1
  >>> A1.bumpA()
A1.a = 2
  >>> A1.bumpA()
A1.a = 3
  >>> A1.bumpA()
A1.a = 4

  >>> import A2
  >>> A2.bumpA()
A2.a = 1
  >>>
  >>> A2.bumpA()
A2.a = 2

Notice that A1.a and A2.a are different - each module has its own namespace, there is no collision.

If I reload a module it gets reset to its initial state:
  >>> reload(A2)
<module 'A2' from 'A2.pyc'>
  >>> A2.bumpA()
A2.a = 1

Kent

Dimitri D'Or wrote:
> Dear Kent,
> 
> Consider I'm working with an interactive session during which I have already
> run some scripts. Those scripts have produced several variables, say, e.g.,
> a and b. Now I execute myscript which also creates variables named a and b,
> but with a possibly different type or content. To be sure that the variables
> I find in my workspace after the execution of myscript were created by this
> script and not by another one, I want to reset the workspace.
> 
> Otherwise, how can I make a difference between variables having the same
> name but created by two different scripts?
> 
> Maybe this question is too much related to my Matlab experience and not
> relevant into Python's philosophy. Please tell me what I should do.
> 
> Dimitri
> 
> -----Message d'origine-----
> De : tutor-bounces+dimitri.dor=fssintl.com at python.org
> [mailto:tutor-bounces+dimitri.dor=fssintl.com at python.org] De la part de Kent
> Johnson
> Envoyé : vendredi 14 janvier 2005 12:03
> Cc : tutor at python.org
> Objet : Re: [Tutor] reinitializing namespace
> 
> I think you may be looking for something that is not needed in Python or
> that you can easily do 
> another way.
> 
> If you are running a script from the command line, e.g.
>   > python myscript.py
> 
> then myscript.py will have a completely fresh runtime environment every time
> you call it.
> 
> If you are running the script by importing in another module, then you can
> use reload() to reload 
> the imported script. That will reinitialize the namespace of the module,
> which for your purposes 
> *is* the global namespace of the module.
> 
> Please give us more details about how you will run the script and what kind
> of problem you anticipate.
> 
> Kent
> 
> Dimitri D'Or wrote:
> 
>>Hello Michael,
>>
>>Thank you for your answer. Actually, my question is not specific to
>>interactive sessions. I've written a script that loads some modules,
> 
> create
> 
>>variables and show figures. What I would like to find, is a command for
>>clearing all the created variables and close all figures before beginning
>>the execution of the script. This command will be placed at the beginning
> 
> of
> 
>>the script and automatically reinitialize the namespace. The utility of
> 
> this
> 
>>command is to guarantee that all the variables that are available in the
>>namespace after the execution of the script were created by it and are not
>>remainders from older commands or scripts. Do you think it is possible to
> 
> do
> 
>>such a thing?
>>
>>I'm coming from the Matlab world and I want to find equivalents for the
>>"clear" and "close" matlab commands.
>>
>>Thank you for your help,
>>
>>Dimitri
>>
>>
>>-----Message d'origine-----
>>De : Michael Janssen [mailto:mi.janssen at gmail.com] 
>>Envoyé : jeudi 13 janvier 2005 19:29
>>À : Dimitri D'Or
>>Cc : tutor at python.org
>>Objet : Re: [Tutor] reinitializing namespace
>>
>>On Thu, 13 Jan 2005 13:20:11 +0100, Dimitri D'Or
>><dimitri.dor at fssintl.com> wrote:
>>
>>
>>
>>>For some purpose, I would like to reinitialize the main namespace, i.e. I
>>
>>want
>>
>>
>>>to delete all the variables I have created through the use of functions or
>>>keyboard entries.
>>
>>
>>Hello Dimiti,
>>
>>sound like you're talking about an interactive session. Otherwise
>>(within a script) it would be a really bad idea to try this (better
>>put your stuff into functions, that don't create global variables).
>>
>>Even in an interactive session it sounds like a not that brilliant
>>idea, especially since I can't think of a way other than using exec
>>"del %s" % key for appropriate keys from globals(). Finding
>>"appropiate" keys is one tricky thing.
>>
>>Why not end your ugly python session and start a new one? You can
>>define all your imports in the python startfile (on Linux, consult
>>python manpage. On Windows, I don't know). You can also define useful
>>functions or variables in your python startfile. This way, you're
>>really shure that all ugly variables are away without del'iting
>>anything important.
>>
>>regards
>>Michael
>>
>>
>>_______________________________________________
>>Tutor maillist  -  Tutor at python.org
>>http://mail.python.org/mailman/listinfo/tutor
>>
> 
> 
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