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by jsmeaton 2411 days ago
Pyenv is for installing multiple versions of python. Virtualenvs are a layer beneath that.

It’s super useful for maintaining static versions of python, like 2.7, 3.6 and 3.7 when you have many projects that have different python requirements.
1 comments
japhyr 2411 days ago
I understand how this was needed historically, when using the official installer might overwrite the Python you already had installed. But as far as I know, you can download an installer for a new version, run it, and it doesn't touch your previous installation.

For example I've had 3.7 on my macOS system for a while, installed from the official installer, not through Homebrew. I just installed 3.8, which pointed my python3 to 3.8. But my 3.7 was still there; I created an alias python3.7 to point to that. So I can run or install anything I want against 3.7 or 3.8.

Why do we still need pyenv? I'm not asking that antagonistically, I really don't understand at this point and I'm wondering if I'm missing something.

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philwelch 2411 days ago
Sometimes scripts will want to invoke Python as ‘python’ and it’s easier to use pyenv to set $PATH overrides.
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japhyr 2411 days ago
Thank you, that’s the first concrete reason I’ve heard. It also explains why I haven’t run into issues yet using my own aliases.
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heavenlyblue 2411 days ago
Why do you need pyenv to set PATH?
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philwelch 2411 days ago
Maybe you don’t, but it’s a way of doing it.

Specifically, pyenv will dynamically and programmatically link the $PATH for the Python executables (python, pip, etc.) to the desired version as defined either by an environment variable or by the contents of a .python-version file in CWD or an ancestor thereof. The .python-version file can be checked into version control.

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jsmeaton 2411 days ago
Honestly I haven’t used official installations before so I can’t speak to that too much. Pyenv mostly uses official builds though so it’s mostly an automated frontend to manual installs.

I like being able to specify the global and local versions for my projects and the system as a whole. I also use it as a virtualenv manager. It works well with pipenv (which I still use in anger) and vscode.

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