观察者/发布订阅(pub/sub)模式

也就是redis的publish/subscribe模式,一对多关系

在c中可以用回调函数实现,python中还可以用对象传递,主题直接调用观察者对象的方法,以下python实现

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

# 主题/观察者模式
    
# 抽象的通知者(主题,发布者)
class Informer():
    observers = []
    action = ''
    
    def Attach(self, observer):
        self.observers.append(observer)
        
    def Notify(self):
        for o in self.observers:
            o.Update()

# 秘书(主题1)
class Secretary(Informer):
    observers = []
    action = "老板回来了!"
    
    
# 老板(主题2)
class Boss(Informer):
    observers = []
    update = [] # 更新函数接口列表
    action = "我胡汉三回来了!"

    def AddEventCB(self,eventCB):
        self.update.append(eventCB)

    def Notify(self):
        for o in self.update:
            o()
    

# 抽象的观察者
class Observer():
    name = ''
    nformer = None;
    
    def __init__(self, name, secretary):
        self.name = name
        self.secretary = secretary # secretary是观察者要订阅的主题
        
    def Update(self):
        pass

# 看股票的同事(观察者1)
class StockObserver(Observer):
    name = ''
    secretary = None;
    
    def __init__(self, name, secretary): 
        Observer.__init__(self, name, secretary)
        
    def Update(self):
        print("%s %s, 不要看股票了，继续工作" % (self.secretary.action,self.name))
        
    def CloseStock(self):
        print("%s %s, 不要看股票了，TMD快点工作!!!" % (self.secretary.action,self.name))

# 看NBA的同事(观察者2)
class NBAObserver(Observer):
    name = ''
    secretary = None;
    
    def __init__(self, name, secretary):
        Observer.__init__(self, name, secretary)
        
    def Update(self):
        print("%s %s, 不要看NBA了，继续工作" % (self.secretary.action,self.name))

def clientUI():
    # 传递对象实现
    secretary = Secretary()
    stockObserver1 = StockObserver('张三',secretary)    
    nbaObserver1 = NBAObserver('王五',secretary)
    
    secretary.Attach(stockObserver1)    
    secretary.Attach(nbaObserver1)
    
    secretary.Notify()
    
    # 回调函数实现
    huHanShan = Boss()
    stockObserver2 = StockObserver('李四',huHanShan)
    huHanShan.AddEventCB(stockObserver2.CloseStock)
    huHanShan.Notify()
    return


if __name__ == '__main__':
    clientUI();

# 观察者订阅一个主题(把自己的回调函数/对象传递给主题),主题调用观察者的方法来通知观察者的

.ing