__init__.py 文件源码

def subscribe(self, event, callback):
        """ Subscribe a callback to an event

        :arg event: String name of an event to subscribe to
        :callback: The function to call when the event is published.  This can
            be any python callable.

        Use :func:`functools.partial` to call the callback with any other
        arguments.

        .. note:: The callback is registered with the event each time this
            method is called.  The callback is called each time it has been
            registered when the event is published.  For example::

                >>> import asyncio
                >>> import pubmarine
                >>> pubpen = pubmarine.PubPen(asyncio.get_event_loop)
                >>> def message():
                ...     print('message called')
                >>> pubpen.subscribe('test', message)
                >>> pubpen.subscribe('test', message)
                >>> pubpen.publish('test')
                message called
                message called

            If the caller wants the callback to only be called once, it is the
            caller's responsibility to only subscribe the callback once.
        """
        if self._event_list and event not in self._event_list:
            raise EventNotFoundError('{} is not a registered event'
                                     .format(event))

        # Get an id for the subscription
        sub_id = next(self._next_id)

        self._subscriptions[sub_id] = event
        try:
            # Add a method
            self._event_handlers[event][sub_id] = WeakMethod(callback)
        except TypeError:
            # Add a function
            self._event_handlers[event][sub_id] = ref(callback)

        return sub_id