Make operations on set take AbstractSet[object]
#1533
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Previously they were `AbstractSet[Any]`
| # TODO more set operations | ||
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| class frozenset(AbstractSet[_T], Generic[_T]): | ||
| def __init__(self, iterable: Iterable[_T] = ...) -> None: ... | ||
| def copy(self) -> FrozenSet[_T]: ... | ||
| def difference(self, *s: Iterable[Any]) -> FrozenSet[_T]: ... | ||
| def intersection(self, *s: Iterable[Any]) -> FrozenSet[_T]: ... | ||
| def difference(self, *s: Iterable[object]) -> FrozenSet[_T]: ... |
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Hm, __sub__ below (which is implemented the same way in C) takes AbstractSet[_T]; I'm not sure why we can't specify _T here.
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Hmm, good catch both of these should be the same.
However, I think we should change the __sub__ function, in order to allow the following code:
from typing import Set, Union, FrozenSet
s1 = frozenset([1, 2]) # type: FrozenSet[int]
s2 = frozenset([1, '2']) # type: FrozenSet[Union[str, int]]
# currently, mypy you an error on the following line but I don't think it should.
s3 = s1 - s2 # type: FrozenSet[int]What do you think?
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That makes sense from the perspective of minimizing false positives. It seems a shame that mypy won't tell you if you're mixing sets of different types in your operations (which is surely often a bug), but we should generally err on the side of reducing false positives.
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I think we should first decide how to do that for ==; then maybe we'll be able to generalize for other operations on other objects. I think for == there's probably already an open issue.
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Generally looks good; I wonder if we should use |
Previously they were
AbstractSet[Any]