🔒 if __name__ == __main__

[agile rune]

I have seen a number of pysters recommend using if name == main statements for modules and packages, but I don't see it in practice all the often. I know that direct call benefits of using it, but is there any adverse overhead for including it in every imported module? (complexity, performance, maintenance, etc). Thoughts?

[keen imp]

@agile rune

Python help channel opened

Remember to:

• Ask your Python question, not if you can ask or if there's an expert who can help.
• Show a code sample as text (rather than a screenshot) and the error message, if you've got one.
• Explain what you expect to happen and what actually happens.

:warning: Do not pip install anything that isn't related to your question, especially if asked to over DMs.

Closes after a period of inactivity, or when you send !close.

[potent geyser]

I wouldn't expect it to have performance impacts at least
it's just 1 if check

even if you have multiple import statements, you don't actually import the package multiple times
python caches the package the first time you imort, then consecutive calls just go to a look up table
e.g.

# a.py
if __name__ == "__main__":
    pass
else:
    print("hey")

# b.py
import a
import a
import a
import a
import a
import a
```only 1 `hey` gets printed

[tough sapphire]

in some cases, the script you're running may end up being imported (e.g. when you're dealing with multiprocessing, or also, I think, pickle, not sure)

so that if is there to make sure the code is ran only when it's called as the main program

another usecase is to have callable modules

i.e. how python3 -m sqlite3 works

although there you might often find __main__.py used instead

[keen imp]

Python help channel closed

This help channel has been closed and it's no longer possible to send messages here. If your question wasn't answered, feel free to create a new post in #1035199133436354600. To maximize your chances of getting a response, check out this guide on asking good questions.