How to add attributes to Callable?

[vitawasalreadytaken]

I have a simple decorator that just sets an attribute on a function and returns it. The closest I got to checking this is creating a subclass of Callable and adding the attribute to it:

from typing import Callable, cast

class RemoteCallable(Callable):
	rpc_name: str = None

def remote(f: Callable) -> RemoteCallable:
	''' Decorator marking a function as callable via the RPC system. '''
	f = cast(RemoteCallable, f)
	f.rpc_name = f.__name__
	return f

However, this fails with rpc.py:3: error: Invalid base class. What can I do?

[JelleZijlstra]

This isn't currently supported yet, but @ilevkivskyi came up with an elegant approach recently so we can support it; see #2087. Closing as a duplicate of that issue.