23种设计模式之python实现--观察者模式

#理解
#Observer模式是最多应用的模式之一
#在很多的编程语言中，都实现了这种模式，并利用了这种模式
#例子
#订报的例子应该比较合适吧
class publisher(object):
observers=list()
msg=None
def register(self,observer):
self.observers.append(observer)
def disregister(self,observer):
self.observers.remove(observer)
def Notify(self):
for ob in self.observers:
ob.update()
class newspublisher(publisher):
def getMessage(self):
return self.msg
def setMessage(self,msg):
self.msg=msg
class observer:
def update(self):
pass
class people(observer):
def __init__(self,publisher):
self.publisher=publisher
self.publisher.register(self)
def disregister(self):
self.publisher.disregister(self)
def update(self):
print self.publisher.getMessage()
if __name__=="__main__":
news=newspublisher()
person1=people(news)
person2=people(news)
news.setMessage("nihao")
news.Notify()
person1.disregister()
news.setMessage("hello")
news.Notify()