How to initialize a class variable once

George Sakkis george.sakkis at gmail.com
Tue Dec 9 17:31:41 CET 2008


On Dec 9, 10:36 am, Joe Strout <j... at strout.net> wrote:

> On Dec 9, 2008, at 4:31 AM, Brian Allen Vanderburg II wrote:
>
> > There is one situation where a module can be imported/executed  
> > twice, if it is the __main__ module.
>
> That's an excellent point -- this is something I've run into, and it  
> always feels a bit awkward to code around it. What's the standard  
> idiom for avoiding this issue in a complex app?  Have a "main" file  
> that is not imported by anything else, and which does little but  
> launch stuff from some other module?

Yes, I believe that's the common practice. Still, whenever I end up
putting stuff in a "main" file and run into the double import problem
(e.g. when pickling), I do an explicit "from main import *" after all
the definitions, i.e.:

# myscript.py

__all__ = ['foo', 'Bar']

def foo(x,y):
   ...

class Bar(object):
   ....

from myscript import *

if __name__ == '__main__':
    assert foo.__module__ == Bar.__module__ == 'myscript'


George



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