[ty] Use try-call-dunder pattern for __class_getitem__#23066
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Thank you. I agree that our behavior was correct before (because __class_getitem__ is special), but this looks like a very nice simplification. I'll add some additional test cases before merging this.
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| /// Attempt to call a dunder method defined on a class itself (not its metaclass). |
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(not its metaclass)
This is a bit misleading because a __class_getitem__ on the metaclass will (and should!) be found by this method as well. I will adapt this docstring accordingly and add some tests to cover the various ways how __class_getitem__ and __getitem__ on the class and the metaclass can interact.
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…3066) ## Summary I think `__class_getitem__` is a bit different than (e.g.) `__contains__` because it's called on the class itself, not instances... So given `Identity[0]` where `Identity` is a class, using `try_call_dunder` would call `member_lookup_with_policy` with `NO_INSTANCE_FALLBACK`, which would look at the metaclass, but not `Identity` itself. I added `try_call_dunder_on_class` for consistency which calls `member` (without `NO_INSTANCE_FALLBACK`), though as far as this PR is concerned, I think our current behavior was ok? Closes astral-sh/ty#190. --------- Co-authored-by: David Peter <[email protected]>
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Summary
I think
__class_getitem__is a bit different than (e.g.)__contains__because it's called on the class itself, not instances... So givenIdentity[0]whereIdentityis a class, usingtry_call_dunderwould callmember_lookup_with_policywithNO_INSTANCE_FALLBACK, which would look at the metaclass, but notIdentityitself.I added
try_call_dunder_on_classfor consistency which callsmember(withoutNO_INSTANCE_FALLBACK), though as far as this PR is concerned, I think our current behavior was ok?Closes astral-sh/ty#190.