typing: Use PEP 695 syntax in typing.py #104553
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JelleZijlstra
requested review from
gvanrossum,
Fidget-Spinner and
AlexWaygood
as code owners
| @@ -2577,8 +2578,6 @@ def new_user(user_class: Type[U]) -> U: | |||
| At this point the type checker knows that joe has type BasicUser. | |||
| """ | |||
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| # Internal type variable for callables. Not for export. | |||
| F = TypeVar("F", bound=Callable[..., Any]) | |||
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This one was added as part of implementing override earlier in 3.12, so there's no need to keep it around for compatibility.
Lib/typing.py
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| @@ -3203,7 +3202,7 @@ def reveal_type(obj: T, /) -> T: | |||
| return obj | |||
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| def dataclass_transform( | |||
| def dataclass_transform[T]( | |||
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This feels slightly strange to me, as (to me) it implies that dataclass_transform is a function generic around the type variable T. But that's not really true; it's a non-generic function that returns an identity function. I skimmed PEP 695, and it doesn't seem to mention how such cases should be handled.
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IIRC we did think about this and decided that this is indeed how such cases should be spelled (since Callable doesn't have a way yet to spell "generic").
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I think we shouldn't do this since it confuses scoping and much of the point of PEP 695 is to clarify scoping. We can use a callback protocol to spell this.
I'd brought this up somewhere before PEP 695 was accepted, but didn't get much of a response. Presumably since it's not the most common thing and I think e.g. pyre might not even support -> Callable[[T], T]
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Changed to a callback protocol
I filed: |
Lib/typing.py
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| @@ -3203,7 +3202,7 @@ def reveal_type(obj: T, /) -> T: | |||
| return obj | |||
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| def dataclass_transform( | |||
| def dataclass_transform[T]( | |||
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IIRC we did think about this and decided that this is indeed how such cases should be spelled (since Callable doesn't have a way yet to spell "generic").
Lib/typing.py
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| type _Func = Callable[..., Any] | ||
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| def override(method: F, /) -> F: | ||
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| def override[F: _Func](method: F, /) -> F: |
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Yeah, the alias makes that so much more readable, in my opinion. Thanks! Good call @gvanrossum.
* main: (26 commits) pythonGH-101520: Move tracemalloc functionality into core, leaving interface in Modules. (python#104508) typing: Add more tests for TypeVar (python#104571) pythongh-104572: Improve error messages for invalid constructs in PEP 695 contexts (python#104573) typing: Use PEP 695 syntax in typing.py (python#104553) pythongh-102153: Start stripping C0 control and space chars in `urlsplit` (python#102508) pythongh-104469: Update README.txt for _testcapi (pythongh-104529) pythonGH-103092: isolate `_elementtree` (python#104561) pythongh-104050: Add typing to Argument Clinic converters (python#104547) pythonGH-103906: Remove immortal refcounting in the interpreter (pythonGH-103909) pythongh-87474: Fix file descriptor leaks in subprocess.Popen (python#96351) pythonGH-103092: isolate `pyexpat` (python#104506) pythongh-75367: Fix data descriptor detection in inspect.getattr_static (python#104517) pythongh-104050: Add more annotations to `Tools/clinic.py` (python#104544) pythongh-104555: Fix isinstance() and issubclass() for runtime-checkable protocols that use PEP 695 (python#104556) pythongh-103865: add monitoring support to LOAD_SUPER_ATTR (python#103866) CODEOWNERS: Assign new PEP 695 files to myself (python#104551) pythonGH-104510: Fix refleaks in `_io` base types (python#104516) pythongh-104539: Fix indentation error in logging.config.rst (python#104545) pythongh-104050: Don't star-import 'types' in Argument Clinic (python#104543) pythongh-104050: Add basic typing to CConverter in clinic.py (python#104538) ...
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
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