Using ruff to get information for other linters

[delfick]

Hi,

I work on a 4.5 million line Python monolith and I want to be able to make a linter check that finds all the subclasses of a specific class to perform checks on those.

The problem becomes discovering all those subclasses is complicated and slow using the tools we already have.

I'm wondering if it's possible to use ruff to collect that information from the repository to then feed to my existing linter checks?

I tried to look at whether I could use the lsp protocol to ask ruff server for such info and quickly discovered that is not straight forward.

[MichaReiser]

Unfortunately, Ruff doesn't support finding all subclasses of a type.

How complicated is your inheritance structure? You might be able to build something very naive for your specific use case:

• Use the Ruff parser to parse all files, find all classes Y that inherit from X
• Repeat the same process to find all classes that inherit from Y (if you have multi-level inheritance, you can otherwise skip this)

[delfick]

In either case, if I could do what my hacky script does but with a ruff equivalent of libcst I imagine that could work. I don't know how to write rust though.

[MichaReiser]

This might be something where a coding agent like Claude AI might be good at? Or at least, gives you something to start from?

[delfick]

personally I doubt that.

[delfick]

I want something that I can rely on and is deterministic (and this is for a linter that will run in CI)

[MichaReiser]

I'm not saying that you should use AI to identify the sub classes. I'm suggesting to use a coding agent to port your libcst Python script to Rust using Ruff