consider not linking Python by default

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Output of brew config

N/A

Output of brew doctor

N/A

Description of issue

As set out in https://justinmayer.com/posts/homebrew-python-is-not-for-you/ , homebrew python is a support structure for homebrew formulae, not really configured in a way which makes it suitable for use as a user-facing development environment. In particular its upgrade cadence makes it a frequent source of complaints when users' virtual environments break.

I think that it would be a benefit to make Homebrew's python not get linked by default, so that this intention is a bit more obvious, and users do not come to inadvertently depend on a non-reproducible installation of Python from Homebrew that they have installed only by accident as a dependency of another tool.

[SMillerDev]

That's not an article from Homebrew though. I'd suggest that Homebrew Python is akin to Arch Linux python. You can't depend on it always being the same version, but if you need a python version it'll do just fine.

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In addition to the piece I linked already, here are some other opinions about Python and Homebrew:

• from the mac install guide, it is "complicated and trouble-prone" for more than simple scripts https://mac.install.guide/python/#:~:text=complicated%20and%20trouble-prone
• from some random Reddit commenters a few years ago, "do not use homebrew for this for all the reasons you have listed" https://www.reddit.com/r/learnpython/comments/ps1byc/comment/hdn9wmz/
• I have written my own piece on this; mentioning it because while it doesn't have much new (it mostly just cites Mayer) it has been pretty popular https://blog.glyph.im/2023/08/get-your-mac-python-from-python-dot-org.html
• "yet another issue with a homebrew update" https://apple.stackexchange.com/questions/470627/yet-another-issue-with-a-homebrew-update-python-upgrade-no-module-named
• the first party documentation says "Important: Python may be upgraded to a newer version at any time. Consider using a version manager such as pyenv if you require stability" https://docs.brew.sh/Homebrew-and-Python#python-3
• "do not use Homebrew Python for development" https://aviaryan.com/blog/python-mac-setup

I could go on. This is a common pain point for Python developers, who would be better served by a single unified set of instructions, "just get it from python.org", rather than thousands of people rediscovering that Homebrew is not appropriate for Python development one at a time because it doesn't support shareable version locking or synchronized-upgrading schemes.

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Again, we're just talking about a default. I'm not saying that Homebrew is never the right choice, but it is clearly the wrong choice often enough that it seems like requiring the extra explicit step of brew link would give us the best of both worlds.

[SMillerDev]

I think we have different views of the default.

I see the default as someone who is new to programming and just wants a python version because they're reading a book or something about python. They do brew install python and they have a working python version that they can play with.

It seems you see the default as a professional python developer who needs to be forced to use pyenv rather than the homebrew python.

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I still believe my original answer stands, since it's really no different from the situation on Linux:

I'd suggest that Homebrew Python is akin to Arch Linux python. You can't depend on it always being the same version, but if you need a python version it'll do just fine.

[SMillerDev]

An additional note: you can always make a pull request to see what the maintainers of Homebrew (other than the two that responded here) think.

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An additional note: you can always make a pull request to see what the maintainers of Homebrew (other than the two that responded here) think.

OK. I thought that a discussion might be more appropriate, but I'll put up a PR when I have a chance.

[quackerex]

You can't depend on it always being the same version, but if you need a python version it'll do just fine.

Unless you need very specific version of python, homebrew works fine imo. you can install specific version like [email protected]. You can install multiple versions and use python3.x in terminal to use the version you want(and also auto create and source venvs with direnv).

I agree with @glyph that it is weird python is not keg-only. The same way ruby is keg-only to avoid messing with system ruby, it make sense python to be keg-only

[SMillerDev]

The same way ruby is keg-only to avoid messing with system ruby, it make sense python to be keg-only

There is no system python, same way there is no system Java. It's just a wrapper that points to something if it's installed (for python it points to the Command Line Tools)

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for python it points to the Command Line Tools

This may not be a relevant detail, but it points to the selected Xcode, which can be the Xcode CLT, but if you have Xcode proper installed it will be that, following the usual rules

$ xcode-select -p
/Applications/Xcode.app/Contents/Developer
$ /usr/bin/python3 -c 'import sys; print(sys.executable)'
/Applications/Xcode.app/Contents/Developer/usr/bin/python3

This is only possibly relevant because if you have multiple Xcodes installed, it's possible that you can switch what Python version you're getting from /usr/bin/python3 by changing your active Xcode.