ParamType and other typing improvements

[kdeldycke]

PR to track and study the unmerged changes from @AndreasBackx that were left in the stale typing/paramtype. See the discussion at #3329 for context.

I was able to salvage and rebase on top of stable the majority of the initial changes like:

• making ParamType a generic ABC and introducing ParamTypeInfoDict
• adding ParamTypeInfoDict
• updating FuncParamType to a generic
• narrowing of convert() return types
• CompositeParamType generic with abstract arity

Stuff that were made obsolete from PRs merged upstream since the last commit in 2024:

• BoolParamType: rewritten in Fix reconciliation of envvar with default, flag_value and type parameters for flag options #2956
• Choice normalization: already part of Expand Choice token normalization + make generic #2796
• File docstring: already cleaned up in Break up arguments section #2586

Other stuff that I skipped as too strict:

• _compat.py t.Any to t.AnyStr
• File generic with t.AnyStr
• _is_file_like with t.AnyStr

I also extracted from the original typing/paramtype the refactor of convert_type which is not strictly related to typing improvements and live in its own PR for later evaluation at: #3372

Related to #2805

[AndreasBackx]

We should probably update the example in the docs as well: https://click.palletsprojects.com/en/stable/parameter-types/. Maybe also inline the version updates in the docs.

Approving as this is already an improvement and I don't see any regressions from popping up, besides perhaps the tuple type checking?

[kdeldycke]

We should probably update the example in the docs as well: https://click.palletsprojects.com/en/stable/parameter-types/. Maybe also inline the version updates in the docs.

Just updated the docs at: ded5b69

[kdeldycke]

Thanks @AndreasBackx for reviewing your own code and the approval! 😎 Unless you find some quick win to add, I propose to consider this PR ready for final review/merge.

Again, the main objective here is to clear the backlog of PRs and close global branches like typing/paramtype.

[kdeldycke]

Any reason @Rowlando13 that you merged into main and not stable? Anyway, thanks for the merge and removal of typing/paramtype!

[kdeldycke]

Any reason @Rowlando13 that you merged into main and not stable?

Just answered my question based on yesterday's activity: seems like we target main because we stated an 8.x release cycle (8.4.0 in this case), and it seems the tradition is to target stable for 8.3.x/8.4.x kind of releases.

[Rowlando13]

Yep