1.类的继承
类的继承
继承是面向对象的重要特性之一，
继承关系继承是相对两个类而言的父子关系
子类继承了父类的所有公有属性和方法，
继承，实现了代码重用
使用继承
继承可以重用已经存在的数据和行为，减少代码的重复编写,
Python在类名后使用一对括号来表示继承关系，括号中的即类为父类
class Myclass(ParentClass)，
如果父类定义了__init__方法，子类必须显式调用父类的__init__方法，
ParentClass.__init__(self,[args...])
如果子类需要扩展父类的行为，可以添加__init__方法的参数.
#!/usr/bin/env python#-*- coding:utf-8 -*-class People(object): color = 'yellow' def think(self): self.color = "black" print "I am a %s " % self.color print ("I am a thinker") class Chinese(People): pass cn = Chinese()print cn.colorcn.think() 父类中有构造函数：
#!/usr/bin/env python#-*- coding:utf-8 -*-class People(object): color = 'yellow' def __init__(self): print "Init..." self.dwell = 'Earth' def think(self): print "I am a %s " % self.color print ("I am a thinker")class Chinese(People): passcn = Chinese()print cn.dwellcn.think() 参数大于两个：
#!/usr/bin/env python#-*- coding:utf-8 -*-class People(object): color = 'yellow' def __init__(self,c): print "Init..." self.dwell = 'Earth' def think(self): print "I am a %s " % self.color print ("I am a thinker")class Chinese(People): def __init__(self): People.__init__(self,'red') passcn = Chinese()
Super 函数
class A(object): def __init__(self): print "enter A" print "leave A"class B(object): def __init__(self): print "enter B" super(B,self),__init__() print "leave B"b = B()
#!/usr/bin/env python#-*- coding:utf-8 -*-class People(object): color = 'yellow' def __init__(self,c): print "Init..." self.dwell = 'Earth' def think(self): print "I am a %s " % self.color print ("I am a thinker")class Chinese(People): def __init__(self): super(Chinese,self).__init__('red') passcn = Chinese()cn.think() #!/usr/bin/env python#-*- coding:utf-8 -*-class People(object): color = 'yellow' def __init__(self,c): print "Init..." self.dwell = 'Earth' def think(self): print "I am a %s " % self.color print ("I am a thinker")class Chinese(People): def __init__(self): super(Chinese,self).__init__('red') def talk(self): print "I like taking."cn = Chinese()cn.think()cn.talk()
多重继承
Python支持多重继承，第一个类可以继承多个父类
语法:
class class_name(Parent_c1,Parent_c2,...)
注意:
当父类中出现多个自定义的__init__的方法时，
多重继承，只执行第一个累的__init_方法，其他不执行。
#!/usr/bin/env python#-*- coding:utf-8 -*-class People(object): color = 'yellow' def __init__(self): print "Init..." self.dwell = 'Earth' def think(self): print "I am a %s " % self.color print ("My home is %s ") % self.dwellclass Martian(object): color = 'red' def __init__(self): self.dwell = 'Martian'class Chinese(People,Martian): def __init__(self): People.__init__(self)cn = Chinese()cn.think() #!/usr/bin/env python#-*- coding:utf-8 -*-class People(object): def __init__(self): self.dwell = 'Earth' self.color = 'yellow' def think(self): print "I am a %s " % self.color print ("My home is %s ") % self.dwellclass Martian(object): color = 'red' def __init__(self): self.dwell = 'Martian' def talk(self): print "I like talking"class Chinese(Martian,People): def __init__(self): People.__init__(self)cn = Chinese()cn.think()cn.talk()
3.类的属性总结
类属性，也是公有属性，
类的私有属性，
对象的共有属性，
对象的私有属性，
内置属性，
函数的局部变量，
全局变量，
#/usr/bin/env python# -*- coding:utf-8 -*-class MyClass(object): var1 = '类属性，类的公有属性 var1' __var2 = '类的私有属性 __var2' def func1(self): self.var3 = '对象的公有属性 var3' self.__var4 = '对象的私有属性 __var4' var5 = '函数的局部变量'mc = MyClass()mc.func1() #调用后才测打印出var3print mc.var1print mc._MyClass__var2print mc.var3mc1 = MyClass()# mc1.func1() #mc1没有调用方法print mc1.var3
通过类访问：
#/usr/bin/env python # -*- coding:utf-8 -*- # @time :2018/1/2 21:06 # @Author :FengXiaoqing # @file :__init__.py.py # var6 = '全局变量 ' class MyClass(object): var1 = '类属性，类的公有属性 var1' ##定义在方法外 __var2 = '类的私有属性 __var2' def func1(self): self.var3 = '对象的公有属性 var3' ##定义在方法内 self.__var4 = '对象的私有属性 __var4' var5 = '函数的局部变量' def func2(self): print self.var1 print self.__var2 print self.var3 print self.__var4 print self.var6 mc = MyClass() mc.func1() mc.func2() print '*'*50 print mc.__dict__ print MyClass.var1 #print MyClass.__var2 #不测通过类访问 print mc.var3 #对象的属性只能通过对象来访问 #print MyClass.__var4 print MyClass.__dict__
4.类的方法总结
公有方法
私有方法
类方法
静态方法
内置方法
class MyClass(object): name = 'Test' def func1(self): print self.name, print "我是公有方法." self.__func2() #func1间接调用了func2的私有方法 def __func2(self): print self.name, print "我是私有方法." def classFun(self): print self.name, print "我是类方法." def staticFun(self): print s.name, print "我是静态方法."mc = MyClass()mc.func1()
调用类方法:用装饰器
@classmethod def classFun(self): print self.name, print "我是类方法." def staticFun(self): print s.name, print "我是静态方法."mc = MyClass()mc.func1()MyClass.classFun()
调用静态方法：
@staticmethod def staticFun(): print MyClass.name, print "我是静态方法."mc = MyClass()mc.func1()MyClass.classFun()MyClass.staticFun()
调用内置方法:
class MyClass(object): name = 'Test' def __init__(self): self.func1() self.__func2() self.classFun() self.staticFun() def func1(self): print self.name, print "我是公有方法." def __func2(self): print self.name, print "我是私有方法." @classmethod def classFun(self): print self.name, print "我是类方法." @staticmethod def staticFun(): print MyClass.name, print "我是静态方法."mc = MyClass()