What does if __name__ == “__main__”: do?

궁금해서 찾아보았는데 과제하는데 도움이 될 것 같아서 공부삼아 기록한다.

When your script is run by passing it as a command to the Python interpreter,

python myscript.py

all of the code that is at indentation level 0 gets executed. Functions and classes that are defined are, well, defined, but none of their code gets run. Unlike other languages, there's no main() function that gets run automatically - the main() function is implicitly all the code at the top level.

결국은 실행할 main 함수가 없으면 indentation level 0에 해당하는 것이 implicit하고 main으로 간주하고 실행한다는 말.

# file one.py

def func():

print("func() in one.py")

print("top-level in one.py")

if __name__ == "__main__":

print("one.py is being run directly")

else:

print("one.py is being imported into another module")

# file two.py

import one

print("top-level in two.py")

one.func()

if __name__ == "__main__":

print("two.py is being run directly")

else:

print("two.py is being imported into another module")

python one.py # When one.py executes

top-level in one.py

one.py is being run directly

python two.py # When two.py executes

top-level in one.py

one.py is being imported into another module

top-level in two.py

func() in one.py

two.py is being run directly

Reference site : https://stackoverflow.com/questions/419163/what-does-if-name-main-do