On 4/20/07, Christian Heimes
Brett Cannon schrieb:
When a module is being executed as a script, ``__main__`` will be set to a true value. For all other modules, ``__main__`` will be set to a false value. This changes the current idiom of::
if __name__ == '__main__': ...
to::
if __main__: ...
The current idiom is not as obvious and could cause confusion for new programmers. The proposed idiom, though, does not require explaining why ``__name__`` is set as it is.
With the proposed solution the convenience of finding out what module is being executed by examining ``sys.modules['__main__']`` is lost. To make up for this, the ``sys`` module will gain the ``main`` attribute. It will contain a string of the name of the module that is considered the executing module.
What about
import sys if __name__ == sys.main: ...
You won't have to introduce a new global module var __name__ and it's easy to understand for newbies and experienced developers. The code is only executed when the name of the current module is equal to the executed main module (sys.main). IMO it's much less PIT...B then introducing __main__.
True, but it does introduce an import for a module that may never be used if the module is not being executed. That kind of sucks for minor performance reasons. But what do other people think? -Brett