ruff/crates/ty_python_semantic/resources/mdtest/binary/classes.md

Binary operations on classes

Union of two classes

Unioning two classes via the | operator is only available in Python 3.10 and later.

[environment]
python-version = "3.10"

class A: ...
class B: ...

reveal_type(A | B)  # revealed: types.UnionType

Union of two classes (prior to 3.10)

[environment]
python-version = "3.9"

class A: ...
class B: ...

# error: "Operator `|` is unsupported between objects of type `<class 'A'>` and `<class 'B'>`"
reveal_type(A | B)  # revealed: Unknown

Other binary operations resulting in UnionType

[environment]
python-version = "3.12"

class A: ...
class B: ...

def _(sub_a: type[A], sub_b: type[B]):
    reveal_type(A | sub_b)  # revealed: types.UnionType
    reveal_type(sub_a | B)  # revealed: types.UnionType
    reveal_type(sub_a | sub_b)  # revealed: types.UnionType

class C[T]: ...
class D[T]: ...

reveal_type(C | D)  # revealed: types.UnionType

reveal_type(C[int] | D[str])  # revealed: types.UnionType