# coding=utf-8 # # Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2023 All Rights Reserved # # Licensed under CLOUD LINUX LICENSE AGREEMENT # http://cloudlinux.com/docs/LICENSE.TXT from typing import Callable, Protocol class Signal(Protocol): def register(self, listener: Callable) -> Callable: ... # def unregister(self, listener: Callable) -> Callable: # ... class Emitter(Signal): # NOTE(vlebedev): registering a listener will keep it alive (i.e. not being garbage collected) # until it's explicitly unregistered. def __init__(self): self._listeners = set() def register(self, listener: Callable): if not callable(listener): raise ValueError("Listener must be callable") self._listeners.add(listener) return listener # TODO(vlebedev): Might be problems with references to e.g. class methods. # It's not that obvious how to handle them properly as they are transient/ephemeral. # For more info have a look at https://docs.python.org/3/library/weakref.html#weakref.WeakMethod # def unregister(self, listener: Callable): # self._listeners.discard(listener) # return listener def __call__(self, *args, **kwargs) -> None: exceptions = [] for listener in tuple(self._listeners): if listener is None: continue try: listener(*args, **kwargs) except Exception as e: exceptions.append(e) if exceptions: raise ExceptionGroup("Exceptions occurred in listeners", exceptions)