Method __subclasscheck__

Lib/typing.py:2001–2025

(cls, other)

            cls.__protocol_attrs__ = _get_protocol_attrs(cls)

    def __subclasscheck__(cls, other):
        if cls is Protocol:
            return type.__subclasscheck__(cls, other)
        if (
            getattr(cls, '_is_protocol', False)
            and not _allow_reckless_class_checks()
        ):
            if not getattr(cls, '_is_runtime_protocol', False):
                _type_check_issubclass_arg_1(other)
                raise TypeError(
                    "Instance and class checks can only be used with "
                    "@runtime_checkable protocols"
                )
            if (
                # this attribute is set by @runtime_checkable:
                cls.__non_callable_proto_members__
                and cls.__dict__.get("__subclasshook__") is _proto_hook
            ):
                _type_check_issubclass_arg_1(other)
                non_method_attrs = sorted(cls.__non_callable_proto_members__)
                raise TypeError(
                    "Protocols with non-method members don't support issubclass()."
                    f" Non-method members: {str(non_method_attrs)[1:-1]}."
                )
        return _abc_subclasscheck(cls, other)

    def __instancecheck__(cls, instance):
        # We need this method for situations where attributes are