Faking out __name__ == __main__

[Bengt Richter]

On Mon, 1 Nov 2004 10:06:09 +0200, aleaxit at yahoo.com (Alex Martelli) wrote:

>Josiah Carlson <jcarlson at uci.edu> wrote:
>
>> bokr at oz.net (Bengt Richter) wrote:
>> > 
>> > On Sun, 31 Oct 2004 17:05:59 -0500, Ed Leafe <ed at leafe.com> wrote:
>> >  >>> def test():
>> >  ...     d = {'__name__': '__xxxx__'}
>> >  ...     execfile('tmain.py', d)
>> 
>> I believe it is technically more Pythonic to use __import__ rather than
>> execfile, if only because you have access to the module itself when you
>> are done.
>
>Unfortunately, while __import__ does take parameters giving local and
>global namespaces, it doesn't use them in anywhere like the way that
>execfile does.  In particular, how would you "force __name__" with
>__import__, as per this thread's subj?  I don't think you can...
>
It seems from a quick hack that you can fake it though, by importing a dummy
and filling it:

 Python 2.3.2 (#49, Oct  2 2003, 20:02:00) [MSC v.1200 32 bit (Intel)] on win32
 Type "help", "copyright", "credits" or "license" for more information.
 >>> print '%s\n%s%s' %('-'*40,open('empty.py').read(),'-'*40)
 ----------------------------------------

 ----------------------------------------
 >>> print '%s\n%s%s' %('-'*40,open('tmain.py').read(),'-'*40)
 ----------------------------------------
 print 'before'
 print 'bef localnames:', locals().keys(), locals()['__name__']
 print 'bef globalnames:', globals().keys(), globals()['__name__']

 glob_before = 'glob_before'
 class Before(object):
     def m(self): print glob_before, glob_after

 if __name__ == '__main__':
     glob_after = 'glob_after'
     class After(object):
         def m(self): print glob_before, glob_after
     print 'after'
     print 'aft localnames:', locals().keys(), locals()['__name__']
     print 'aft globalnames:', globals().keys(), globals()['__name__']
 ----------------------------------------
 >>> import empty
 >>> empty.__dict__['__name__']
 'empty'
 >>> empty.__dict__['__name__'] = '__main__'
 >>> empty.__dict__['__name__']
 '__main__'
 >>> execfile('tmain.py', empty.__dict__)
 before
 bef localnames: ['__builtins__', '__name__', '__file__', '__doc__'] __main__
 bef globalnames: ['__builtins__', '__name__', '__file__', '__doc__'] __main__
 after
 aft localnames: ['glob_before', '__builtins__', '__file__', 'After', 'glob_after', '__name__', '
 __doc__', 'Before'] __main__
 aft globalnames: ['glob_before', '__builtins__', '__file__', 'After', 'glob_after', '__name__',
 '__doc__', 'Before'] __main__
 >>> dir(empty)
 ['After', 'Before', '__builtins__', '__doc__', '__file__', '__name__', 'glob_after', 'glob_before']
 >>> empty.Before().m()
 glob_before glob_after
 >>> empty.After().m()
 glob_before glob_after
 >>> empty.glob_before
 'glob_before'
 >>> empty.__name__='tmain'
 >>> empty.__file__ = r'c:\pywk\clp\tmain.py'
 >>>
 >>> help(empty)
 Help on module tmain:

 NAME
     tmain

 FILE
     c:\pywk\clp\tmain.py

 DATA
     glob_after = 'glob_after'
     glob_before = 'glob_before'

 >>> type(empty)
 <type 'module'>

I haven't really explored all the ramifications ;-)

Regards,
Bengt Richter