if __name__ == "__main__"

Martin von Loewis loewis at informatik.hu-berlin.de
Fri Dec 21 11:38:46 EST 2001

crennert at pbmplus.com (Chris Rennert) writes:

> Could someone please fill me in on how the if __name__ == "__main__
> thing works.  I am reading through some tutorials and I never really
> get a clear definitive answer on that.
> Is this like main() in C?  

No. __name__, on module level, is the name of the module. So if you
would modify urllib.py to contain

print __name__

then "import urllib" would print


Now, the file that you pass on the command line of the interpreter
does not have a module name (because it really isn't a module), so
__name__ is set to the string "__main__" inside that code. That allows
you to write a file that is used both as a module and as a program.


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