flake8 precommit hook

[mstimberg]

Continuing the work started with #1435 to make Brian's code more readable and "best practice" compatible, this adds another precommit hook, this time for flake8. It will flag common issues such as local variables or imports that are never used, or minor stylistic issues such as using not element in list instead of element not in list. I configured it in a conservative way to not be too radical/annoying for Brian's code base, e.g. I excluded all tests and __init__.py files, since they use wildcard imports quite extensively.

Not sure anyone cares about this very much, but tagging @oleksii-leonov, @bdevans, @denisalevi just in case 😋

[bdevans]

Looks good to me!
Just one point to mention, there are now several files to keep in sync with versions of dependencies e.g. .pre-commit-config.yaml and .devcontainer/dev-requirements.txt. Would it be possible to consolidate them all into one location that gets read by the others?

[mstimberg]

Thanks @bdevans.

Just one point to mention, there are now several files to keep in sync with versions of dependencies e.g. .pre-commit-config.yaml and .devcontainer/dev-requirements.txt. Would it be possible to consolidate them all into one location that gets read by the others?

I was wondering about the same thing, but I did not find an easy solution. We could use an approach like the one described here: pre-commit/pre-commit#945 (comment) , which would mean that pre-commit wouldn't install anything but just use what is installed on the system. This would be ok for running the pre-commit hooks in the CI, but for running them locally it would mean that we lose the isolation that pre-commit provides. The user could update a tool locally, and thereby potentially change the result of applying the hooks – this would be very confusing if the commit then gets refused by the CI on GitHub.
Going the other way, i.e. somehow parsing .pre-commit-config.yaml and using it to pip install requirements is probably the better way. If anyone wants to have a go at anything like that, please go ahead 😉