def get_unspecified_from_annotation()

in chz/factories.py [0:0]

• 18 lines of code
• 13 McCabe index (conditional complexity)

def get_unspecified_from_annotation(annotation: TypeForm) -> Callable[..., Any] | None:
    if typing.get_origin(annotation) is type:
        base_type = typing.get_args(annotation)[0]
        if not isinstance(getattr(base_type, "__origin__", base_type), type):
            # No unspecified for type[SpecialForm] e.g. type[int | str]
            # TODO: annotated
            return None
        return type[base_type]  # type: ignore[return-value]

    if is_union_type(annotation):
        type_args = typing.get_args(annotation)
        if type_args and len(type_args) == 2 and type(None) in type_args:
            unwrapped_optional = [t for t in type_args if t is not type(None)][0]
            if callable(unwrapped_optional):
                return unwrapped_optional
        return None

    if is_instantiable_type(annotation):
        return annotation  # type: ignore[return-value]

    if annotation is None:
        return lambda: None

    # Probably a special form
    return None