Using dunder parameter name in builtins._SupportsLessThan#4264
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srittau merged 2 commits intopython:masterfrom Jun 25, 2020
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Using dunder parameter name in builtins._SupportsLessThan#4264srittau merged 2 commits intopython:masterfrom
builtins._SupportsLessThan#4264srittau merged 2 commits intopython:masterfrom
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PEP 544 intentionally did not specify whether method conformance check in protocol inference should look at parameter names. For example, it's up to the type checker to decide whether a class with method defined as `def foo(self, x: int)` would implement a protocol with method `def foo(self, y: int)`. Mypy decided to ignore parameter names altogether, but we Pyre team decided to be more strict and refuse to match different parameter names (as it is unsound to do so when those methods are invoked with named parameters). Since Pyre also rely on the typeshed stubs, we want to make sure at least the important stubs on typeshed conform to our standard. This PR changes `_SupportsLessThan.__lt__` (introduced in python#4192) to use dunder (i.e. positional-only) parameter name specified in PEP484. This change should not affect mypy since it ignores parameter names, but will make Pyre happy when builtin functions like `sorted` is used. Note there are likely to be other cases where we might want this. We'll submit subsequent PRs in a demand-driven fashion.
srittau
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I think it makes sense for most of these "simple" protocols to use dunder argument names. We also should move this protocol over to _typeshed.pyi at some point.
hauntsaninja
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PEP 544 intentionally did not specify whether method conformance check in protocol inference should look at parameter names. For example, it's up to the type checker to decide whether a class with method defined as
def foo(self, x: int)would implement a protocol with methoddef foo(self, y: int).Mypy decided to ignore parameter names altogether, but we Pyre team decided to be more strict and refuse to match different parameter names (as it is unsound to do so when those methods are invoked with named parameters). Since Pyre also rely on the typeshed stubs, we want to make sure at least the important stubs on typeshed conform to our standard.
This PR changes
_SupportsLessThan.__lt__(introduced in #4192) to use dunder (i.e. positional-only) parameter name specified in PEP484. This change should not affect mypy since it ignores parameter names, but will make Pyre happy when builtin functions likesortedis used.Note there are likely to be other cases where we might want this. We'll submit subsequent PRs in a demand-driven fashion.