sys.modules and __main__ obscureness

[Fuzzyman]

Hello all,

I am messing with namespaces, so that code I exec thinks it is
executing in the __main__ module.

I have the following code :

import imp
import sys

# can't call the module '__main__' or 'new_module' returns the real one
module = imp.new_module('_')
namespace = module.__dict__
namespace['__name__'] = '__main__'

# next put things into the names
# e.g. :
namespace['variable'] = 3

sys.modules['__main__'] = module

print module
print namespace
import __main__
print __main__.__dict__['variable']

This code behaves differently when entered into an interactive
interpreter session. When run as a program you will see that module and
namespace have both become None !!

However the code works, but to get access to the namespace again I have
to import __main__. I just wondered why ?


All the best,


Fuzzyman
http://www.voidspace.org.uk/python/index.shtml