Python12（接口继承，子类调用父类，多态）

接口继承：

基类不用实现内部逻辑，只是为了规范子类，可以用abc模块中以添加装饰器的方式实现

 import abc
 class All_file(metaclass=abc.ABCMeta):

     @abc.abstractmethod
     def read(self):
         pass

     @abc.abstractmethod
     def write(self):
         pass

 class Disk(All_file):
     def read(self):
         print("Disk read")
     def write(self):
         pass
 class Cdrom(All_file):
     def read(self):
         pass
     def write(self):
         pass

 m1 = Disk()
 m1.read()
 m1.write()

在子类中调用父类方法：

 class Vehiale:
     country = "China"
     def __init__(self,name,speed,load,power):
         self.name = name
         self.speed = speed
         self.load = load
         self.power = power

     def run(self):
         print("kaidongla")

 class Subway(Vehiale):
     def __init__(self,name,speed,load,power,line):
         Vehiale.__init__(self,name,speed,load,power)
         self.line = line
     def show_info(self):
         print(self.speed,self.line,self.load,self.name,self.power)
     def run(self):
         Vehiale.run(self)
         print("%s %s 线,开动啦" %(self.name,self.line))

 line13=Subway("100m/s",13,1000,"北京地铁","电")
 line13.show_info()
 line13.run()

多态：

不同的实例可以去调用同一个方法，但实现的效果不同。

 class H2O:
     def __init__(self,name,temperature):
         self.name = name
         self.temperature = temperature
     def turn_ice(self):
         if self.temperature < 0:
             print('[%s]温度太低结冰了'%self.name)
         elif self.temperature > 0 and self.temperature < 100:
             print('[%s]液化成水'%self.name)
         elif self.temperature>100:
             print('[%s]温度太高变成水蒸气了'%self.name)

 class Water(H2O):
     pass
 class Ice(H2O):
     pass
 class Steam(H2O):
     pass

 w1 = Water('水',25)
 i1 = Ice('冰',-20)
 s1 = Steam('蒸汽',300)

 # w1.turn_ice()
 # i1.turn_ice()
 # s1.turn_ice()
 #多态反映的是一种运行时候的状态
 def func(obj):
     obj.turn_ice()

 func(w1)
 func(i1)
 func(s1)