pyenv support

[jefftriplett]

I am not sure how far you want to deep dive with having pyenv support, but I noticed this behavior today:

❯ python --version
Python 3.9.5

❯ py --version
Python 3.10.0a4+

Basically, pyenv global lets you set up a bunch of global python versions including which version is your default aka resolves first when you run python or python3.

At first glance, this might not seem important, but VS Code and a few other apps, do not like it if you have Python 3.6 installed, but not linked to a global version like python3.6.

❯ pyenv global
3.9.5
3.8.10
3.7.10
3.10-dev
3.6.13
3.5.10
2.7.18

# this order is installed here:
❯ cat ~/.pyenv/version
3.9.5
3.8.10
3.7.10
3.10-dev
3.6.13
3.5.10
2.7.18

I would expect py --version to give me Python 3.9.5 instead of Python 3.10.0a4+ because other apps seem to just work with the default python or python3 version that I have setup.

py -3.9 --version works but is less tab-completable than py.

PS: I don't think this is a deal-breaker, but I suspect it'll be a common issue now that more and more tutorials and guides are starting to recommend that people use pyenv over homebrew or other python versions.

[brettcannon]

You can set PY_PYTHON to the Python version you want the default to point to, e.g. PY_PYTHON=3.9 would mean your 3.9.5 install would take precedence over your 3.10-dev install.

But I assume you still want explicit pyenv support? Or does that environment variable solve this for you?

[benspaulding]

I came here for a similar reason as Jeff, a little tripped up at py giving me a different version than python when I have pyenv installed. In my case it was because pyenv respects .python-version files.

I tried to get it to work with a .python-version file and hit the same issue.

> cat .python-version; and set -gx PY_PYTHON (head -n1 .python-version); and echo $PY_PYTHON; and py --version
3.7.10
3.7.10
Python 3.9.5

Is making PY_PYTHON accept major.minor.patch a possibility, or does that go against some of py’s design decisions?

This is an awesome, project — thanks for your efforts!

[treyhunner]

I put this in my ~/.zshrc` and it worked:

export PY_PYTHON=$(head --lines 1 ~/.python-version | cut --delimiter=. --fields=1,2)

Before I saw this:

$ py --version
Python 3.10.0a6+

And now:

$ py --version
Python 3.9.1

[brettcannon]

@benspaulding I will have to think about whether I want to be lenient on PY_PYTHON with a patch version, as I also don't want people to think that by specifying a patch version they will actually get that specific version as they won't.

@treyhunner Thanks for that! Do you want to send me a PR to add that to the FAQ in the README (with a note that the syntax is for bash/zsh and for fish it's set -g -x (head --lines 1 ~/.python-version | cut --delimiter=. --fields=1,2))? If not, I assume you don't mind if I copy that into there?

[treyhunner]

@brettcannon PR opened #111 👍

Feel free to reword as desired

[brettcannon]

If anyone is interested, #108 is looking for feedback on how to surface any parsing issues with the environment variables.

[brettcannon]

This is now covered in the README thanks to c9e92a5! Thanks everyone for helping out to resolve this!