观察者模式

class Subject(object):
    observers=[]
    info=‘‘
    def __init__(self,info):
        self.info = info
    def notify(self):
       for o in self.observers:
           o.display(self.info)

    def attach(self,observer):
        self.observers.append(observer)
    def deattach(self,observer):
        self.observers.remove(observer)

class Observer(object):
    def __init__(self,name):
        self.name=name

    def display(self,info):
        print ‘notice ‘+ self.name + ‘ that ‘+ info

class NBAObserver(Observer):
    pass

class F1Observer(Observer):
    pass

    
if __name__==‘__main__‘:
    subject = Subject(‘win win win win‘)
    observer = NBAObserver(‘NBA‘)
    subject.attach(observer)
    observer = F1Observer(‘F1‘)
    subject.attach(observer)
    subject.notify()