Somebody asked me a question and I honestly didn't try it before, So it was interesting to know what exactly happens when we name a module __main__.py. So I named a module __main__.py, imported it in another file with name test.py. Surprisingly when I tried to run test.py it prints nothing and none of the functions of __main__.py are available in test.py. Here is the contents of these files :
Here is the contents of __main__.py :
def add(a,b):
result = a+b
return result
print(__name__)
if __name__=='__main__':
print(add(1,2))
Here is the contents of test.py :
import __main__
Why isn't the print statement from __main__.py reached? Although when I rename the __main__.py with some other name such as func.py, the program runs correctly and the line that prints module's name works fine.
When you run python test.py, the test.py module itself is already present in sys.modules with the key "__main__" (see top-level code environment in the docs). The import __main__ will just return this existing cache hit, so the presence of a __main__.py file on sys.path is irrelevant.
These modifications to test.py will prove that point:
import sys
print(sys.modules['__main__']) # it's already in there before the import
import __main__
print(__main__.__file__) # this should be the abspath of test.py