Switch to a specific version of Python on macOS

[milosgajdos]

Output of brew config

HOMEBREW_VERSION: 4.1.17
ORIGIN: https://github.com/Homebrew/brew
HEAD: 35746e0a6ba6c3c5cfe56d99f79d9ec9f52ee15f
Last commit: 33 hours ago
Core tap JSON: 23 Oct 15:41 UTC
HOMEBREW_PREFIX: /usr/local
HOMEBREW_BROWSER: open
HOMEBREW_CASK_OPTS: []
HOMEBREW_EDITOR: nvim
HOMEBREW_GITHUB_API_TOKEN: set
HOMEBREW_MAKE_JOBS: 8
Homebrew Ruby: 2.6.10 => /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.6.10_1/bin/ruby
CPU: octa-core 64-bit icelake
Clang: 14.0.0 build 1400
Git: 2.37.1 => /Library/Developer/CommandLineTools/usr/bin/git
Curl: 8.1.2 => /usr/bin/curl
macOS: 12.6.8-x86_64
CLT: 14.2.0.0.1.1668646533
Xcode: 14.2

Output of brew doctor

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: Some installed kegs have no formulae!
This means they were either deleted or installed manually.
You should find replacements for the following formulae:
  aws-okta

Warning: Some installed formulae are deprecated or disabled.
You should find replacements for the following formulae:
  aws-okta

Warning: You have unlinked kegs in your Cellar.
Leaving kegs unlinked can lead to build-trouble and cause formulae that depend on
those kegs to fail to run properly once built. Run `brew link` on these:
  docutils
  kubernetes-cli

Description of issue

I am trying to switch python from 3.11 to 3.10 on my laptop

I thought running the link command would do the job:

$ brew link --overwrite python@3.10
Warning: Already linked: /usr/local/Cellar/python@3.10/3.10.13
To relink, run:
  brew unlink python@3.10 && brew link python@3.10

But that accomplishes nothing:

$ python3 -V
Python 3.11.6

[SMillerDev]

The easiest way to address a specific Homebrew version: python3.12 -V
If you need a very specific version: save yourself some headache and use pyenv

[Bo98]

Yes, we support this but not via brew link. Add $(brew --prefix python@3.10)/libexec/bin to the front of your PATH and the default python3 will change.

See brew caveats python@3.10 for more info.

[keeely]

So glad I found that little gem. I was adding my own ~/bin path and adding symlinks in there just felt... ugly.

[soheil]

Why not provide a simple way to link to an older version without having to change my PATH everyone I run a bash cmd specially if you brew automatically updates python version making all previously install pip packages inaccessible?

[SMillerDev]

The simple way to link specific versions while keeping you packages is virtual environments. It's what the Python ecosystem is explicitly moving towards.

[soheil]

OK so it's even worse not only you have to reinstall all your packages you have to it in all your virtual envs too. $O(n^2)$ and it's not even the computer doing it.

[p-linnane]

Use pyenv or pipx. Homebrew's Python is mostly for other formulae that require it. You shouldn't be using it as a general purpose Python install.