Python print 的时候出现<__main__.Observer object at 0x0224F3B0>

Question

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()

if name=='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

Answer 1

observer = Observer(subject)

self.subject.add_observer(self)

Causes the observer to be added to subject.observers

print("{}你好，以下是今日的天气播报：\n{}\n").format(o,weather_data)

o is observer, print observer
So it will output <main.Observer object at 0x0224F3B0>

You can take a look at the "__str__" method and modify the return value of print observer

Answer 2

In the init function of Class Observer, the self.subject.add_observer(self) statement appends the instance object of Weather to the Weather observers list.