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PEP 612 (Parameter Specification variables) tracker #4827
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Yup!
Reacted by Sebastian Rittau and Alex WaygoodPyright has had full support for PEP 612 for a long time now.
Reacted by Sebastian Rittau, Changsheng Wu, Jesse and Alex Waygoodpytype does not yet support this. I opened google/pytype#786.
Not yet planned :( Will post updates here.
- Reacted by Sebastian Rittau and Alex Waygood
Is there any update on this issue? Has anyone started to work on the support in mypy? Pytype?
I'm aware that full support for PEP 612 is not easy to implement, but perhaps some minimal support could be added that simply treats all ParamSpecs as
Any? That would allow us to start usingParamSpecandConcatenatewithin typeshed without regressing the behavior for mypy users. This minimal support apparently was already implemented in pytype. It looks like @hauntsaninja made some progress on support in mypy in this PR, but there hasn't been any update in this tracking issue since Jan 2020.Maybe we need to think about ways to support declarations that are conditioned on support for specific type checking features. Perhaps something like a
_typing_features.pyifile that defines symbols like__PEP612__. Type checkers that support specific features could assume these symbols areTrueand use the type declarations that take advantage of these features. Type checkers that don't support the feature would assumeFalseand fall back on alternate declarations that don't use these features.I think work on mypy support has stalled.
Another, more forceful, approach could be that we simply start using them in typeshed (perhaps with a liberal sprinkling of type ignores). It would then be individual type checkers' responsibilities to add support for new features, and the ecosystem can move forward without having to wait for the slowest type checker to update itself. We could start doing this say six months or a year after a PEP has been accepted.
Could we just cheat and derive
ParamSpecfromAnyintyping_extensions, until type checkers add support? That said, I'm also fine to just start usingParamSpecand use# type: ignore. Maybe we could have a draft PR that implementsParamSpecin a file where it's useful to judge the fallout?But in general I agree that we should be more aggressive about adding features, so as not to hold more up-to-date type checkers back.
Maybe we could have a draft PR that implements ParamSpec in a file where it's useful to judge the fallout?
ParamSpeccan now be used in argument and return type positions, although# type: ignoreis necessary. It's still untested whether it works as part of aGenericclass.Now partly supported by mypy, no support for
Concatenateyet.I checkmarked pytype. While it doesn't support
ParamSpecper se, it accepts it.- added a commit that references this issue
on Apr 7, 2022 I think we can now use ParamSpec without limitations in typeshed.
I think we can now use ParamSpec without limitations in typeshed.
There's still a mypy bug I'm waiting on: #7689 (comment). I'll add it to the tracker.
Reacted by Sebastian RittauI think we can now use ParamSpec without limitations in typeshed.
There's still a mypy bug I'm waiting on: #7689 (comment). I'll add it to the tracker.
The mypy issue has now been closed!
This issue is supposed to track when we can start to use parameter specification variables (PEP 612) in typeshed. Support is needed in released versions of:
ParamSpecsupportConcatenatesupport (PEP-612 Concatenate not recognized properly mypy#11833)ParamSpec(Class Generic ParamSpec cannot be used in Callable mypy#12011)