Add vf upgrade $venv to upgrade major/minor Python versions

[Freso]

Stock Python venv module has an --upgrade function that lets you upgrade virtualenvs created via that, but that doesn't seem to work with virtualfish created venvs. Having a similar mode for vf (e.g., vf upgrade $venv) would be great.

[RaitoBezarius]

That'd be really nice, I'm interested into sending a PR for this, how should I proceed?

[justinmayer]

Hi Ryan. Your contribution implementing this functionality would be most helpful. Let us know if you have any specific questions. We look forward your pull request! ✨

[RaitoBezarius]

Hi @justinmayer — thank you! I'm looking at the repo, I see a update_python.fish which looks like exactly what we want, should I just wrap into a command which activates the venv, run the update python with no argument (choosing the default python), and that's it?

[RaitoBezarius]

It sounds like it has been built for this: 6e269b0

[justinmayer]

Ah, so it seems that existing Update Python plugin already addresses this issue. Could you perhaps test it and confirm?

[RaitoBezarius]

@justinmayer It's working ~quite well, I'm not sure if we expect it to restore all packages which were in the former venv (because pip freeze can be itself broken during updates).

I guess all we would like is the ability to get the packages without using pip freeze (by reading the structure ourselves: $VIRTUALFISH_HOME/some-venv/lib/python-old-version/sites-packages/*)

[justinmayer]

@RaitoBezarius: Having personally run into situations when Python interpreters have been yanked out from underneath the virtual environments that relied on them (I'm looking at you, Homebrew), I agree that it would be nice to recover from those situations in a more graceful manner than is currently available.

I guess all we would like is the ability to get the packages without using pip freeze (by reading the structure ourselves: $VIRTUALFISH_HOME/some-venv/lib/python-old-version/sites-packages/*)

I agree that may indeed be a good approach, particularly since the installed version numbers are available in the *.dist-info directories. Is this something you might willing to assist with and implement? We could certainly use the help! 😅

[justinmayer]

Regarding upgrading virtual environments, I have a WIP solution that I will submit shortly. While I was working on it, I realized that introspecting virtual environment state is difficult and cumbersome, so I came up with a solution via #190 whereby one can run vf ls --details to show outdated/broken Python interpreters.

Anyone have any feedback on its implementation? Comments on PR #190 would be most welcome. 😊

[justinmayer]

I submitted a pull request (#191) for the new vf upgrade command in order to (hopefully) get some feedback on its implementation. I also included a screencast to demonstrate the new features, so be sure to check it out.

In addition to the other PR mentioned above, comments on this new PR would also be appreciated: #191

[justinmayer]

I'm quite pleased with the new upgrade feature, so it's time to ship it. 🚀