On Sun, Jan 2, 2022 at 8:32 PM <jbrockmendel@gmail.com> wrote:
Also, the only realistic use case that I have ever heard people ask for is "NOT str", as in "any sequence except str".
Found this thread while trying to address some of the "type: ignore" comments in pandas. A couple of examples where this feature would be useful:
A bunch of functions are just optimized isinstance checks where we'd like to overload:
``` @overload def is_float(x: float | np.floating) -> True: ...
@overload def is_float(x: AnythingBut[float | np.floating]) -> False: ... ```
Maybe this could use TypeGuard: def is_float(x: object) -> TypeGuard[float|np.floating]: ... (Though perhaps the new, *precise* typeguard that's being discussed in another thread <https://mail.python.org/archives/list/typing-sig@python.org/thread/EMUD2D424...> on this list would be better.)
Similar but a bit more complicated, we have a `def find_common_type(types: list[np.dtype | ExtensionDtype]) -> np.dtype | ExtensionDtype:` where we'd like an overload to declare `def find_common_type(types: list[np.dtype]) -> np.dtype`.
AFAICT we can't do this without an AnythingBut[X] annotation.
For this, I think overload actually works just fine. E.g. from typing import * @overload def foo(a: list[int]) -> int: ... @overload def foo(a: list[str]) -> str: ... @overload def foo(a: list[int|str]) -> int|str: ... def foo(a): ... reveal_type(foo([1,2,3])) # int reveal_type(foo(['a', 'b'])) # str x: list[int|str] = [1, 2, 'a', 'b'] reveal_type(foo(x)) # int|str -- --Guido van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* <http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-c...>