patch-classmethod.py

def is_classmethod(method: FunctionType) -> bool:
    """Determine if a method is a classmethod or not by searching for a classmethod sentinel."""
    bound_to = getattr(method, "__self__", None)
    if not isinstance(bound_to, type):
        return False
    name = method.__name__
    for clazz in bound_to.__mro__:
        descriptor = vars(clazz).get(name)
        if descriptor is not None:
            return isinstance(descriptor, classmethod)
    return False

def _patch_base_generic_alias_getattr_for_generic_classmethods() -> None:
    def __getattr__(self: Any, name: str) -> Any:  # type: ignore[misc]
        """A generic classmethod aware patch for __getattr__ of all base generic classes."""
        if is_classmethod(class_def := original_getattr(self, name)):
            param_to_args = dict(zip(self.__origin__.__parameters__, self.__args__, strict=True))
            function = class_def.__func__
            return FunctionType(
                function.__code__,
                function.__globals__,
                function.__name__,
                function.__defaults__,
                tuple(
                    CellType(
                        param_to_args.get(value, value) if isinstance(value, Hashable) else value
                    )
                    for value in map(attrgetter("cell_contents"), function.__closure__)
                ),
            ).__get__(class_def.__self__)
        return class_def

    if _BaseGenericAlias.__getattr__ is not __getattr__:
        original_getattr = _BaseGenericAlias.__getattr__
        _BaseGenericAlias.__getattr__ = __getattr__