A property decorator that permits a different type in the setter

typed_property.py

from typing import Any, Callable, Generic, NamedTuple, Optional, Tuple, TypeVar

GetterT = TypeVar("GetterT")
SetterT = TypeVar("SetterT")

GetterCallable = Callable[[Any], GetterT]
SetterCallable = Callable[[Any, SetterT], SetterT]


def typed_property(getter: GetterCallable) -> "TypedPropertyGetter[GetterT]":
    return TypedPropertyGetter(getter)


class TypedPropertyGetter(Generic[GetterT]):
    def __init__(self, getter: GetterCallable) -> None:
        self._getter = getter
        self._setter: Optional[SetterCallable] = None

    def __get__(self, obj, obj_type) -> GetterT:
        return self._getter(obj)

    def __set__(self, obj, value: SetterT) -> SetterT:
        if self._setter is None:
            raise TypeError(f"{obj!r} is not callable")
        return self._setter(obj, value)

    def setter(
        self, setter: Callable[[Any, SetterT], object]
    ) -> "TypedPropertyGetter[GetterT]":
        self._setter = setter
        return self


class ConsoleDimensions(NamedTuple):
    width: int
    height: int


class Console:
    def __init__(self) -> None:
        self._size = ConsoleDimensions(80, 25)

    @typed_property
    def size(self) -> ConsoleDimensions:
        return self._size

    @size.setter
    def _set_size(self, new_size: Tuple[int, int]) -> Tuple[int, int]:
        width, height = new_size
        self._size = ConsoleDimensions(width, height)
        return new_size


console = Console()
print(console.size)

console.size = (10, 20)
print(console.size)

console.size = ConsoleDimensions(3, 4)
print(console.size)