#!/usr/bin/env python

# -*- coding: utf-8 -*-

"""

Reference: http://www.slideshare.net/ishraqabd/publish-subscribe-model-overview-13368808

Author: https://github.com/HanWenfang

"""

class Provider:

def __init__(self):

self.msg_queue = []

self.subscribers = {}

def notify(self, msg):

self.msg_queue.append(msg)

def subscribe(self, msg, subscriber):

self.subscribers.setdefault(msg, []).append(subscriber)

def unsubscribe(self, msg, subscriber):

self.subscribers[msg].remove(subscriber)

def update(self):

for msg in self.msg_queue:

if msg in self.subscribers:

for sub in self.subscribers[msg]:

sub.run(msg)

self.msg_queue = []

class Publisher:

def __init__(self, msg_center):

self.provider = msg_center

def publish(self, msg):

self.provider.notify(msg)

class Subscriber:

def __init__(self, name, msg_center):

self.name = name

self.provider = msg_center

def subscribe(self, msg):

self.provider.subscribe(msg, self)

def run(self, msg):

print("{} got {}".format(self.name, msg))

def main():

message_center = Provider()

fftv = Publisher(message_center)

jim = Subscriber("jim", message_center)

jim.subscribe("cartoon")

jack = Subscriber("jack", message_center)

jack.subscribe("music")

gee = Subscriber("gee", message_center)

gee.subscribe("movie")

fftv.publish("cartoon")

fftv.publish("music")

fftv.publish("ads")

fftv.publish("movie")

fftv.publish("cartoon")

fftv.publish("cartoon")

fftv.publish("movie")

fftv.publish("blank")

message_center.update()

if __name__ == "__main__":

main()

### OUTPUT ###

# jim got cartoon

# jack got music

# gee got movie

# jim got cartoon

# jim got cartoon

# gee got movie