See the rejected PEP 299 for a previous version of this idea: https://www.python.org/dev/peps/pep-0299/

And a discussion on python-dev: https://mail.python.org/pipermail/python-dev/2006-March/062951.html

Eric

On 10/1/2021 3:38 PM, Paul Bryan wrote:
How about the following?

def __main__():
    ...

      
Behavior:

1. Load module as normal.
2. If __name__ is "__main__" or module is named in python -m, call __main__ function.

Paul


On Fri, 2021-10-01 at 15:35 -0400, Jonathan Crall wrote:
I was curious if / what sort of proposals have been considered for simplifying the pattern: 

```
def main():
    ...

if  __name__ == "__main__":
    main()
```

I imagine this topic must have come up before, so I'd be interested in any relevant history. 

But unless I'm missing something, it seems like adding some easier alternative to this cumbersome entrypoint syntax would be worth considering.

My motivation for writing this suggestion is in an attempt to stop a common anti-pattern, where instead of defining a `main` function (or a function by any other name) an simply calling that by adding the above two lines, a lot of Python users I work with will just start dumping their logic into the global scope of the module.

Needless to say, this can have consequences. If there was some default builtin, let's call it `__main__` for now (open to suggestions), that took a function as an argument and conditionally executed it if `__name__ == "__main__"` in the caller's scope, that would allow us to simplify the above boilerplate to a single line with no extra indentation:

```
def main():
    ...

__main__(main)
``` 

In addition to being simpler, it would allow users to avoid the trap of adding logic that impacts the global scope. It would also save me some keystrokes, which I'm always grateful for.

Furthermore, it could be used as a decorator (and the use-case wouldn't be unreasonable!), and we all know how much new Python users love decorators when they find out about them.

```
@__main__
def main():
    ...
```

Maybe having such a builtin would discourage globals and help new users get the use-decorators-everywhere bug out of their system.

--
-Dr. Jon Crall (him)
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