class Observer(object):
def __init__(self,subject): self.subject = subject self.weather = self.subject.weather self.subject.add_observer(self) def update(self,weather,temperature,tips): self.weather = weather self.temperature = temperature self.tips = tips self.display() def display(self): return ("今日天气:{} \n今日气温: {} \n今日建议:{}").format(self.weather,self.temperature,self.tips)
class Weather(object):
def __init__(self): self.observers = [] self.weather = "" self.temperature = "" self.tips = "" def add_observer(self,observer): self.observers.append(observer) def delete_observer(self,observer): if observer in self.observers: self.observers.remove(observer) def notify(self): for observer in self.observers: observer.update(self.weather,self.temperature,self.tips) def add_data(self,weather,temperature,tips): self.weather = weather self.temperature = temperature self.tips = tips self.notify()
ifname=='main':
subject= Weather() observer = Observer(subject) subject.add_data('多云转阴','10~23℃','请注意别感冒!') subject.add_observer('张三') subject.add_observer('李四') subject.add_observer('Ben') def Print(): ox = subject.observers for o in ox: weather_data = observer.display() print("{}你好,以下是今日的天气播报:\n{}\n").format(o,weather_data) Print()
初学Python,在做观察者模式的时候发现print会打印出多余的东西
<main.Observer object at 0x0224F3B0>你好,以下是今日的天气播报:
今日天气:多云转阴
今日气温: 10~23℃
今日建议:请注意别感冒!
请问这是什么原因,以及解决之道
使得observer被添加到subject.observers中去
o就是observer,print observer
所以会输出
可以看一下“__str__”方法,可以修改print observer时的返回值
在Class Observer的init函数中,self.subject.add_observer(self)语句将Weather的实例对象append到Weather的observers list里面了。