publish_subscribe pattern

Author: indieyourself

README.md

@@ -31,4 +31,5 @@ Current Patterns:
 * template
 * command 
 * memento 
-* visitor
+* visitor
+* publish_subscribe

publish_subscribe.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python
+
+'''http://www.slideshare.net/ishraqabd/publish-subscribe-model-overview-13368808'''
+
+classProvider:
+def__init__(self):
+self.msgQueue= []
+self.subscribers={}
+
+defnotify(self, msg):
+self.msgQueue.append(msg)
+
+defsubscribe(self,msg, subscriber):
+ifnotmsginself.subscribers:
+self.subscribers[msg] = []
+self.subscribers[msg].append(subscriber) #unfair
+else:
+self.subscribers[msg].append(subscriber)
+
+defunSubscribe(self,msg, subscriber):
+self.subscribers[msg].remove(subscriber)
+
+defupdate(self):
+formsginself.msgQueue:
+ifmsginself.subscribers:
+forsubinself.subscribers[msg]:
+sub.run(msg)
+self.msgQueue= []
+
+classPublisher:
+def__init__(self, msgCenter):
+self.provider=msgCenter
+
+defpublish(self, msg):
+self.provider.notify(msg)
+
+
+classSubscriber:
+def__init__(self,name,msgCenter):
+self.name=name
+self.provider=msgCenter
+
+defsubscribe(self, msg):
+self.provider.subscribe(msg, self)
+
+defrun(self, msg):
+print"%s got %s"%(self.name, msg)
+
+
+defmain():
+messageCenter=Provider()
+
+fftv=Publisher(messageCenter)
+
+jim=Subscriber("jim", messageCenter)
+jim.subscribe("cartoon")
+jack=Subscriber("jack", messageCenter)
+jack.subscribe("music")
+gee=Subscriber("gee", messageCenter)
+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")
+
+messageCenter.update()
+
+if__name__=="__main__":
+main()