Use attrs

[LecrisUT]

Testing out how hard it would be to replace dataclass with attrs

• Replace standalone dataclass: Trivial
• attrs.define subclassing dataclasses.dataclass:
  • __init__ kwargs are not inheritted
• Converting tmt.utils.field: unknown
  • How to simplify type-checking and forward all kwargs to click/metadata/attrs.field
• Converting tmt.utils.FieldMetadata: unknown
• Converting tmt.utils.DataContainer: unknown

---

Pull Request Checklist

• implement the feature
• write the documentation
• extend the test coverage
• update the specification
• adjust plugin docstring
• modify the json schema
• mention the version
• include a release note

[martinhoyer]

Hi @LecrisUT, why attrs? Did I miss something?

[happz]

One immediate comment, there are way too many formatting changes, obscuring the actual changes. Empty lines added and removed, indentation changes... I wonder how that happens, we should be using the same autopep8 settings in pre-commit.

The rest seems safely trivial, but need to re-read once the dust settles.

[LecrisUT]

Hmm, that must have been from my IDE, but I thought it was already setup to use ruff-format, so I'm not sure why this got changed and not in the pre-commit, I can review the commit more and minimize these

[LecrisUT]

@martinhoyer attrs has more convenient api for adding converter, validator, etc. We did discuss it a bit here and there, e.g. #2766. Overall it would be good to touch up on how dataclasses are used and see how this can be improved, simplified and what else we can gain from attrs. So far what this could help with:

• Decoupling the dataclass from the python version
• Simplifying the __init__ and such by having the normalizer and such handled by the attrs built-ins
• Cleaner interface using decorators for validator and default (no decorator sintax for converter yet)
• More extensibility potential. E.g. coupling with a json validator

[lukaszachy]

Just to note version: Oldest attrs we need to support is 20.3.0 in el9 (from appstream repo)

[LecrisUT]

I've tried something very basic like:

@attrs.define
class DiscoverCoprData(DiscoverStepData):
    packages: list[str] = tmt.utils.field(
        option=("-p", "--package"),
        default_factory=list,
    )

But this didn't go as intended, the __init__ did not inherit the kwargs