觀察者模式

被坑進國企，做過半個月的flex，一直不太清楚“事件”的原理，問別人都說底層的東西。

偶然看到觀察者模式，瞭解一下原理，大概明白了。就是回調函數的使用，記下來，以後遇到類似的問題，可以嘗試一下用這種方式解決

#coding=utf-8
'''
Created on 2015-8-31

@author: xhw

@explain: pass
'''

class Subject:  
    '''
    @summary:被觀察者； 被觀察者一般被觀察者需要有三個方法
    1.register：添加監聽者
    2.deregister：移除監聽者
    3.notify_observers：通知Observer
    '''
    def register(self, observer):  
        pass  
  
    def deregister(self, observer):  
        pass  
  
    def notify_observers(self):  
        pass  
  
class Observer:
    '''
    @summary: 觀察者；觀察者一般至少需要有一個方法，用來處理相應的事件
    '''
    def update(self, temperature, humidity, pressure):  
        pass  

#coding=utf-8
'''
Created on 2015-8-13

@author: xhw

@explain: pass
'''

import time

class Subject(object):
    '''
    @summary: 被觀察者
    '''
    def __init__(self):
        self.observer_list = []
    
    def register(self, observer):
        if observer not in self.observer_list:
            self.observer_list.append(observer)
  
    def deregister(self, observer):  
        if observer in self.observer_list:
            self.observer_list.remove(observer)  
  
    def notify_observers(self,Temp):  
        for observer in self.observer_list:
            observer.update(Temp)

    
class Observer_1(object):
    '''
    @summary: 觀察者
    '''
    def __init__(self,Subject):
        self.subject = Subject
        self.subject.register(self)
    
    def update(self,Temp):
        if Temp <=60 and Temp >45:
            print "溫水:%s℃"%Temp
        elif Temp <= 45:
            print "涼水:%s℃"%Temp
    
class Observer_2(object):
    '''
    @summary: 觀察者
    '''
    def __init__(self,Subject):
        self.subject = Subject
        self.subject.register(self)
    
    def update(self,Temp):
        if Temp >60 and Temp <100:
            print "熱水:%s℃"%Temp
        elif Temp >= 100:
            print "開水:%s℃"%Temp
            
class Observer_3(object):
    '''
    @summary: 觀察者
    '''
    def __init__(self,Subject):
        self.subject = Subject
        self.subject.register(self)
    
    def update(self,Temp):
        if Temp < 90:
            print "溫度不夠，不能泡麪..."  
    
def trigger():
    Temp = 0
    '''觀察對象'''
    Water_Temp = Subject()
    '''添加觀察對象'''
    O_1 = Observer_1(Water_Temp)
    O_2 = Observer_2(Water_Temp)
    O_3 = Observer_3(Water_Temp)
    while Temp <= 100:
        if Temp >= 90:
            '''移除觀察者'''
            Water_Temp.deregister(O_3)
        '''觸發事件（通知觀察者）'''
        Water_Temp.notify_observers(Temp)
        Temp += 5
        time.sleep(2)
        
if __name__ == "__main__":
    trigger()