What does if __name__ == "__main__" mean in Python ? Quickly Explained

Understanding Python Idioms

Let’s try to understand the left hand side of this idiom:
if __name__

What exactly __name__ is ?

__name__ is a special variable in python whose value depends on how the code which contains is getting executed.

When we run the .py file as a standalone program, a script,

__name__ variable equals “__main__”.

If the file containing this code is being imported, __name__ variable is set to module’s name.

So, clearly, if you execute a testFile.py file directly like this: python testFile.py

print("__name__ is set to %s "% __name__)

def testFunc():
    print("I am Test Func")

if __name__ == "__main__":
    testFunc()

Output:

__name__ is set to __main__
I am Test Func

And if you import the testFile in otherTestFile.py:

import testFile

Output:

__name__ is set to testFile

Also, testFunc does not gets called as it fails the if condition.

Thanks !