[issue44791] Substitution of ParamSpec in Concatenate
Mehdi2277
report at bugs.python.org
Sun Feb 20 04:11:54 EST 2022
Mehdi2277 <med2277 at gmail.com> added the comment:
Concatenate[int, ...] I would interpret as a function signature with first argument int, followed by arbitrary arguments afterwards. I haven't run into this case, but ... is allowed in other spots Paramspec is allowed currently.
P = Paramspec("P")
class Foo(Generic[P]):
...
Foo[...] # Allowed
Callable[..., None] # Allowed
Are there any other places a paramspec is allowed? Generic type argument, first argument to callable, last to concatenate, anything else?
I'm unaware of any type checking use case for Concatenate[int, ...]. You can practically get same thing by using a paramspec variable without using it elsewhere so that it captures, but then effectively discards that information.
def use_func1(f: Callable[Concatenate[int, P], None]) -> None:
...
def use_func2(f: Callable[Concatenate[int, ...], None]) -> None:
...
feels like those two signatures should encode same information.
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nosy: +med2277
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<https://bugs.python.org/issue44791>
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