stdlib: Replace overload hack in operator.itemgetter by PEP 646 unpack - #11136
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Co-authored-by: Sebastian Rittau <srittau@rittau.biz>
Co-authored-by: Sebastian Rittau <srittau@rittau.biz>
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$ python -c 'import operator; operator.attrgetter(attr="a")'
Traceback (most recent call last):
File "<string>", line 1, in <module>
TypeError: attrgetter() takes no keyword argumentsShould I send a PR fixing it? |
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AlexWaygood
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Thanks, this looks good -- I left an inline comment about one more nit, though it doesn't really matter that much.
In general, I'm slightly confused about why we're bothering to make this class generic at all, actually. It doesn't seem like it being generic really does much for us; it's not really possible to express the semantics of this class properly right now, with our current type system. But hey.
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Maybe the best way to type this class would be to do something like this: _T = TypeVar("_T")
_R = TypeVar("_R")
_T1 = TypeVar("_T1")
_T2 = TypeVar("_T2")
_T3 = TypeVar("_T3")
_T4 = TypeVar("_T4")
_T5 = TypeVar("_T5")
_Ts = TypeVarTuple("_Ts")
_Ts1 = TypeVarTuple("_Ts1")
@final
class itemgetter(Generic[_T, Unpack[_Ts]]):
def __new__(cls, __item1: _T1, *items: Unpack[_Ts1]) -> itemgetter[_T1, Unpack[_Ts1]]: ...
@overload
def __call__(self: itemgetter[_T1], obj: SupportsGetItem[_T1, _R]) -> _R: ...
@overload
def __call__(self: itemgetter[_T1, _T2], obj: SupportsGetItem[_T1 | _T2, _R]) -> tuple[_R, _R]: ...
@overload
def __call__(self: itemgetter[_T1, _T2, _T3], obj: SupportsGetItem[_T1 | _T2 | _T3, _R]) -> tuple[_R, _R, _R]: ...
@overload
def __call__(
self: itemgetter[_T1, _T2, _T3, _T4], obj: SupportsGetItem[_T | _T2 | _T3 | _T4, _R]
) -> tuple[_R, _R, _R, _R]: ...
@overload
def __call__(
self: itemgetter[_T1, _T2, _T3, _T4, _T5], obj: SupportsGetItem[_T1 | _T2 | _T3 | _T4 | _T5, _R]
) -> tuple[_R, _R, _R, _R, _R]: ...
@overload
def __call__(self, obj: SupportsGetItem[Any, Any]) -> Any: ...This will crash pytype right now, but I'd actually be curious to see the mypy_primer output, if you fancy trying it! |
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
I asked myself the same question and I thought it was either used before or is intended to be used in the future so I didn't bother make the class non-generic because I don't have the context for why it was made generic in the first place. |
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This reverts commit 9b2b979.
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According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉 |
AlexWaygood
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There's definitely some big TODOs remaining with this class, but this seems like it maintains the status quo for users while simplifying the stub. So I'm happy to merge this now. Thanks!
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