# 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)
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