Add completions for CLI - #1118

sorry, don't really want to add a dependency for this

also the strategy used by argcomplete is too slow to be useful, it adds ~200ms per <tab> press which is well past the noticeable "slowness"

I believe the more correct way to do something like this would be to pregenerate completions as part of the packaging and provide those separately

Thanks for the quick reply.

In my opinion completions are pretty important for friendly, usable CLI tools. I understand pre-commit isn't first and foremost a CLI tool, but I found I missed completions when I was trying to remember how to install a commit-msg hook just now (typing -h is too much for me :))

I guess we could write completions by hand for the relatively small number of available commands and not need any new dependencies, but this is definitely the easiest and most integrated way to provide completions.

it's not particularly difficult to generate completions scripts, here's some prior art: https://github.com/asottile/all-repos/blob/master/all_repos/complete.py

Would expose some command like:

eval "$(pre-commit complete)"

which you could put in your rc file

Just seen your followups, yep it's laggy (tbh I'm using WSL so I'm used to laggy terminals, didn't really notice...). I think the lag could be alleviated with a refactor to avoid importing before parsing CLIs, I've used this style of autocompletion before and it worked a charm.

In any case, I don't really have the time to invest into writing anything substantial right now, shall I close this and open an issue about completions instead?

yeah I don't really want to play the import whackamole game -- there's not a good reason to runtime-compute completions when we can generate them all statically