Python File Structure on GitHub

Question

I've been looking around at some open source projects on Python, and I'm seeing a lot of files and patterns that I'm not familiar with.

First of all, a lot of projects just have a file called setup.py, which usually contains one function:

setup(blah, blah, blah)

Second, a lot contain a file that is simply called __init__.py and contains next to no information.

Third, some .py files contain a statement similar to this:

if __name__ == "__main__"

Finally, I'm wondering if there are any "best practices" for dividing Python files up in a git repository. With Java, the idea of file division comes pretty naturally because of the class structure. With Python, many scripts have no classes at all, and sometimes a program will have OOP aspects, but a class by class division does not make that much sense. Is it just "whatever makes the code the most readable," or are there some guidelines somewhere about this?

Answer 1

The setup.py is part of Python’s module distribution using the distrubution utilities. It allows for easy installation of the Python module and is useful when, well, you want to distribute your project as a whole Python module.

The __init__.py is used for Python’s package system. An empty file is usually enough to make Python recognize the directory it is in as a package, but you can also define different things in it.

Finally, the __name__ == '__main__' check is to ensure that the current script is run directly (e.g. from the command line) and it is not just imported into some other script. During a Python script execution only a single module’s __name__ property will be equal to __main__. See also my answer here or the more general question on that topic.