Autoformatting, type-checking, and linting

[impredicative]

In the Python world, auto-formatting, type-checking, and linting are three separate concerns. They are not one and the same.

Regarding auto-formatting, I tried ruff via rye lint but it does not look to have sane defaults, making it useless as I see it. It did not detect or fix various simple issues. I find black more suitable.

Regarding type-checking, mypy is critical to me, although the choice of tool may vary.

Regarding any leftover linting, pylint is what I would compare any other Python linter with.

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My point is that rye lint should probably be removed unless all of the above can be tackled.

[mitsuhiko]

You would need to substantiate the claims a bit that ruff is "useless". Can you demonstrate a case where you expect the lint to detect something but it did not? I find it vastly more likely that there is a bug and we accidentally skipped over a file. Yes, type checking is something that definitely should be added but it's not yet fully clear to me how to best approach this given that mypy has to be sitting inside the dependency tree. There might also be a better choice than mypy and it's something I need to investigate.

[impredicative]

I did check rye lint -v (verbose option) output to confirm that the file was not skipped by ruff. It didn't even check or fix basic whitespace issues, although it did find one other issue. More later.

[impredicative]

With the default options, rye lint --fix (via ruff) doesn't strip multiple trailing newlines in a file. It also doesn't normalize string quotes (single-quoted strings versus double-quoted strings), whereas black does. These are common auto-formatting issues.

[cnpryer]

Have you tried the formatter? What your describing sounds like it'd be handled by the formatter, not the linter. The formatter should also provide options for configuring quote preference.

[impredicative]

@cnpryer rye fmt addressed it. What had me confused was that rye lint --fix is in a manner of speaking also doing some formatting. As such there are two formatters.

[cnpryer]

If there isn't already, there will be a ruff check command that consolidates these features in a way. Maybe that's what you're expecting?

I wouldn't equate formatting to fixing lints.

[impredicative]

@cnpryer I added this to my pyproject.toml:

[tool.rye.scripts]  # Run as "rye run <command>"
check = { chain = ["check-lint", "check-fmt" ] }
"check-lint" = "rye lint"
"check-fmt" = "rye fmt --check"
fix = { chain = ["fix-lint", "fix-fmt" ] }
"fix-lint" = "rye lint --fix"
"fix-fmt" = "rye fmt"

[acalvino4]

+1 for integrating a typechecker into the 'hassle-free' python toolchain. don't particularly care if it's mypy or something else, as long as it works and is fast!

[impredicative]

It sort of does matter if it's mypy or something else. Python's typing module has been updating in every release of Python, and various type checkers that are not mypy could struggle to keep up.

The same concern also applies with various linters and formatters that may struggle to keep up with newer Python syntax.

[mitsuhiko]

The problem with adding typing support today is that the choices of type checkers are not great. I think the best type checker available today for multiple reasons is pyright but unfortunately it also requires node to be installed. It also would require a lot of custom code around it to make it work well for no LSP kind of setups. I do think that at one point it would be great though to have the type checker also integrated.

If nothing better than pyright comes up, I would honestly consider transpiling pyright or bundling a javascript interpreter optionally to run this thing.

[impredicative]

I don't know if https://github.com/Distributive-Network/PythonMonkey qualifies as a JS interpreter.

[impredicative]

I guess it now stands to reason that Astral is working on a Python type-checker.

[lgc2333]

Maybe basedpyright is an another good choice for type checking? It can be installed via pip (it also requires node but the node binary will install via pip too)