maturin-import-hook does not work with Python installed from Mac Homebrew

[miikka]

If you are on macOS and you use a Python installed with Mac Homebrew - brew install python - and you try to install maturin-import-hook into a virtualenv, it won't work. This is because Homebrew installs a sitecustomize.py into the Python standard library directory (/opt/homebrew/Cellar/python@3.13/3.13.5/Frameworks/Python.framework/Versions/3.13/lib/python3.13/sitecustomize.py on my computer right now). When Python tries to import sitecustomize, it ends up importing this file and not the one installed/edited by maturin-import-hook.

A workaround is to install Python in some other way. I'm using uv to manage the virtualenvs, so I used uv venv --managed-python which creates the virtualenv with uv-installed Python.

I wanted to share this information as I was confused about why I couldn't get the import hook to work. I'm not sure if this should be considered a bug in the import hook, but maybe using a .pth file instead of sitecustomize.py could make it work even in this case.

[mbway]

Thanks for the post!
At the very least, the installer should warn if this happens so I will take a look at this and also evaluate whether we can use pth files instead of sitecustomize

[soraxas]

Thanks for the pointer! I want to add that not just mac, but even ubuntu had their own vendor sitecustomize.py (i was SO CONFUSED as to why it didn't work)

$ cat /usr/lib/python3.12/sitecustomize.py 

# install the apport exception handler if available
try:
    import apport_python_hook
except ImportError:
    pass
else:
    apport_python_hook.install()

[mbway]

As mentioned in the documentation it's best not to install into the system interpreter anyway. The OS needs that interpreter for things packaged by the OS so it's best to keep that separate from the interpreter you develop with in my opinion.