Fast Pub-Sub python implementation: starting (I)

A brief explanation

First, before start coding. You must read this, a good article that explains the difference between a publish subscribe and an observer. If you don't want read this article, I think that this graphic will be enough

As we can see in this graphic, an subscriber(callback function) will be attached to an event. Once this step completed, a publisher will add to the event channel a new event firing all the subscribers attached to that event.

Our class

class EventChannel(object):
    def __init__(self):
        self.subscribers = {}

    def unsubscribe(self, event, callback):
        if event is not None or event != ""\
                and event in self.subscribers.keys():
            self.subscribers[event] = list(
                filter(
                    lambda x: x is not callback,
                    self.subscribers[event]
                )
            )

    def subscribe(self, event, callback):
        if not callable(callback):
            raise ValueError("callback must be callable")

        if event is None or event == "":
            raise ValueError("Event cant be empty")

        if event not in self.subscribers.keys():
            self.subscribers[event] = [callback]
        else:
            self.subscribers[event].append(callback)

    def publish(self, event, args):
        if event in self.subscribers.keys():
            for callback in self.subscribers[event]:
                callback(args)

Testing

event_channel = EventChannel()

callback = lambda x: print(x)

event_channel.subscribe("myevent", callback)

event_channel.publish("myevent", "Hello, world!")

# out: "Hello, world!"

event_channel.unsubscribe("myevent", callback)

bus_instance.publish("myevent", "Hello, world!")

# No output

Links

• Pypi
• Github

Wich things will you improve?.Thank you for reading, and write any thought below :D