ruff/crates/red_knot_python_semantic/resources/mdtest/subscript/class.md

Class subscript

Class getitem unbound

class NotSubscriptable: ...


a = NotSubscriptable[0]  # error: "Cannot subscript object of type `Literal[NotSubscriptable]` with no `__class_getitem__` method"

Class getitem

class Identity:
    def __class_getitem__(cls, item: int) -> str:
        return item


reveal_type(Identity[0])  # revealed: str

Class getitem union

flag = True


class UnionClassGetItem:
    if flag:

        def __class_getitem__(cls, item: int) -> str:
            return item

    else:

        def __class_getitem__(cls, item: int) -> int:
            return item


reveal_type(UnionClassGetItem[0])  # revealed: str | int

Class getitem with class union

flag = True


class A:
    def __class_getitem__(cls, item: int) -> str:
        return item


class B:
    def __class_getitem__(cls, item: int) -> int:
        return item


x = A if flag else B

reveal_type(x)  # revealed: Literal[A, B]
reveal_type(x[0])  # revealed: str | int

Class getitem with unbound method union

flag = True

if flag:

    class Spam:
        def __class_getitem__(self, x: int) -> str:
            return "foo"

else:

    class Spam: ...


# error: [call-non-callable] "Method `__class_getitem__` of type `Literal[__class_getitem__] | Unbound` is not callable on object of type `Literal[Spam, Spam]`"
# revealed: str | Unknown
reveal_type(Spam[42])

TODO: Class getitem non-class union

flag = True

if flag:

    class Eggs:
        def __class_getitem__(self, x: int) -> str:
            return "foo"

else:
    Eggs = 1

a = Eggs[42]  # error: "Cannot subscript object of type `Literal[Eggs] | Literal[1]` with no `__getitem__` method"

# TODO: should _probably_ emit `str | Unknown`
reveal_type(a)  # revealed: Unknown