Python观察者模式实践-优快云博客

本文介绍了一种使用Python实现的观察者模式，并提供了一个简单的示例。通过定义抽象主题类和监听器类，实现了主题与多个监听器之间的解耦。当主题状态改变时，所有注册的监听器都会收到通知。

1、观察者模式

class AbstractSubject:
    def register(self, listener):
        raise NotImplementedError("Must subclass me")
 
    def unregister(self, listener):
        raise NotImplementedError("Must subclass me")
 
    def notify_listeners(self, event):
        raise NotImplementedError("Must subclass me")
 
class Listener:
    def __init__(self, name, subject):
        self.name = name
        subject.register(self)
 
    def notify(self, event):
        print (self.name, "received event", event)
 
class Subject(AbstractSubject):
    def __init__(self):
        self.listeners = []
        self.data = None

    def getUserAction(self):
        self.data = raw_input('Enter something to do:')
        return self.data

    # Implement abstract Class AbstractSubject

    def register(self, listener):
        self.listeners.append(listener)
 
    def unregister(self, listener):
        self.listeners.remove(listener)
 
    def notify_listeners(self, event):
        for listener in self.listeners:
            listener.notify(event)

 
if __name__=="__main__":
    # make a subject object to spy on
    subject = Subject()
 
    # register two listeners to monitor it.
    listenerA = Listener("<listener A>", subject)
    listenerB = Listener("<listener B>", subject)
 
    # simulated event
    subject.notify_listeners ("<event 1>")
    # outputs:
    #     <listener A> received event <event 1>
    #     <listener B> received event <event 1>
 
    action = subject.getUserAction()
    subject.notify_listeners(action)
    #Enter something to do:hello
    # outputs:
    #     <listener A> received event hello
    #     <listener B> received event hello

Python Observer Pattern

因为Python版本是3.3，所以用print()和 input()，替换 print和raw_input。

转载于:https://www.cnblogs.com/xuanyuanchen/p/6344380.html