events.py 文件源码

def _listen(cls, event_key, propagate=True, **kw):
        target, identifier, fn = \
            event_key.dispatch_target, event_key.identifier, \
            event_key._listen_fn

        def listen(target_cls, *arg):
            listen_cls = target()
            if propagate and issubclass(target_cls, listen_cls):
                return fn(target_cls, *arg)
            elif not propagate and target_cls is listen_cls:
                return fn(target_cls, *arg)

        def remove(ref):
            key = event.registry._EventKey(
                None, identifier, listen,
                instrumentation._instrumentation_factory)
            getattr(instrumentation._instrumentation_factory.dispatch,
                    identifier).remove(key)

        target = weakref.ref(target.class_, remove)

        event_key.\
            with_dispatch_target(instrumentation._instrumentation_factory).\
            with_wrapper(listen).base_listen(**kw)