Defining main() in python

Possible Duplicate:
What does <if name ==“ main ”:> do?

Often, I see the following code in python programs

if __name__ == '__main__':
main()

I'm following the Python Class on Google code, and it says that it's standard boilerplate code.

Do I really need to write such code in all my scripts?

What functionality would this add to my programs?

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No, you don't have to, but it's invaluable for things like unit testing.

You can create a main in every python file so that, if you run it directly, __name__ will be set to "__main__" and it will run a barrage of tests on the code in question.

If you just import it normally from another program, that doesn't happen, because __name__ is set to a different value.

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It is helpful, when you're importing the files. You can either run the python file as a standalone program, or import some components of it into another programs.

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