Fix issue #3912 : invalid docstring generation of std::array <-> list caster #3916
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This PR achieves MyPy compliance in exchange for potentially very confusing situations where a pybind11-bound function does not accept an input array, and the error message provides zero context why that is (input has the wrong size) |
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These signatures in pybind11 precede the time where MyPy was even a thing, so "non-standard non-spec compliant" seems a bit strong of a qualifier. |
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@wjacob, in >=3.9 we can use the Annotated typing extension to specify the length of the list. Hmm, not sure if there is a standard compliant way to specify the type for anything besides Tuples though. |
| const_name("[") + const_name<Size>() | ||
| + const_name("]")) | ||
| + const_name("]")); | ||
| PYBIND11_TYPE_CASTER(ArrayType, const_name("List[") + value_conv::name + const_name("]")); |
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I think if you make the string typing.Annotated[List[type], size] then pybind11-stubgen will generate the correct thing from this (and if it doesn't then you can just modify it to do so).
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Also note, it's just a string. You don't need typing extensions in pybind11, that's the responsibility of whoever interprets the string.
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Annotated[List[type], size] appears to be the intended standard way to hint the length of a list. PEP 593 shows this use case as an example.
I would just remove typing. from your suggestion since List is not prefixed either.
This PR achieves MyPy compliance in exchange for potentially very confusing situations where a pybind11-bound function does not accept an input array, and the error message provides zero context why that is (input has the wrong size)
@wjakob My understanding is that this PR only changes the type hint and does not affect the error message otherwise. Is there a situation where Annotated[List[str], 2] would be inferior to List[str[2]]?
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Is there a situation where Annotated[List[str], 2] would be inferior to List[str[2]]?
According to #4679 (comment) , plain 2 does not look good
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@Skylion007 @rwgk can we close this one? |
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Closing after #4679 was merged. |
Description
std::array? #3912, by removing size information from list, while this information is helpful, it generates invalid type signatures for mypy and other type checkers.Suggested changelog entry: