python3.x面向对象编程之继承（代码实例）

继承

class People():
    def __init__(self,name,age):
        self.name = name
        self.age = age
        self.friends = []
        print("--doens't run ")
    def eat(self):
        print("%s is eating..." % self.name)
    def talk(self):
        print("%s is talking..." % self.name)
    def sleep(self):
        print("%s is sleeping..." % self.name)

class Man(People):      #Man继承People
    pass

m1 = Man("NiuHanYang",22)
m1.eat()    #Man继承People,直接调用People里的方法

重构父类方法，给父类的方法增加新功能（先执行父类的方法）

class People():
    def __init__(self,name,age):
        self.name = name
        self.age = age
        self.friends = []
        print("--doens't run ")
    def eat(self):
        print("%s is eating..." % self.name)
    def talk(self):
        print("%s is talking..." % self.name)
    def sleep(self):
        print("%s is sleeping..." % self.name)

class Man(People):      #Man继承People
    def piao(self):
        print("%s is piaoing..." % self.name)
    def sleep(self):?#给父类的方法增加新功能?
        People.sleep(self)
        print("man is sleeping  ")

m1 = Man("NiuHanYang",22)
#m1.eat()    #Man继承People,直接调用People里的方法
m1.sleep()

如果要传入参数给子类，要在子类写构造函数

class Man(People):
    def __init__(self,name,age,money):?#self,name,age是父类的参数，有多少写多少；money是新子类新添加的参数
        People.__init__(self,name,age)?  #继承父类
        # super(Man,self).__init__(name,age) #新式类写法，作用和上面一样，不用写父类的名字
        self.money  = money
        print("%s 一出生就有%s money" %(self.name,self.money))

多继承

# class People: 经典类
class People(object): #新式类
#父类1
    def __init__(self,name,age):
        self.name = name
        self.age = age
        self.friends = []
        print("--doens't run ")
    def eat(self):
        print("%s is eating..." % self.name)
    def talk(self):
        print("%s is talking..." % self.name)
    def sleep(self):
        print("%s is sleeping..." % self.name)

class Relation(object):
#父类2
    def make_friends(self,obj): #w1
        print("%s is making friends with %s" % (self.name,obj.name))

class Man(Relation,People):
#继承两个父类
    def __init__(self,name,age,money):
        # People.__init__(self,name,age)
        super(Man,self).__init__(name,age) #新式类写法
        self.money  = money
        print("%s 一出生就有%s money" %(self.name,self.money))
    def piao(self):
        print("%s is piaoing ..... 20s....done." % self.name)
    def sleep(self):
        People.sleep(self)
        print("man is sleeping ")
class Woman(People,Relation):
    def get_birth(self):
        print("%s is born a baby...." % self.name)

m1 = Man("NiuHanYang",22,100)
w1 = Woman("ChenRonghua",26)
#
m1.make_friends(w1)
# w1.name = "陈三炮"
# print(m1.friends[0])

在上面的例子中，父类2没有构造函数，因为

print("%s is making friends with %s" % (self.name,obj.name))  里,self.name,obj.name在父类1存在，不用重新构造

Python2.x和Python3.x多继承的区别

例如下面的程序：

class A:
    def __init__(self):
        print("A")
class B(A):
    pass
    # def __init__(self):
    #     print("B")
class C(A):
    pass
    # def __init__(self):
    #     print("C")
class D(B,C):
    pass
    # def __init__(self):
    #     print("D")

obj = D()

经典类和新式类：

class A:	#经典类
class A(object):	#新式类，在父类添加object效果好

Python3.x经典类和新式类都是统一按广度优先来继承的；而Python2.x经典类是按深度优先继承的，新式类似按广度优先来继承的

多态

一种接口，多种实现。是允许你将父对象设置成为和一个或更多的他的子对象相等的技术，赋值之后，父对象就可以根据当前赋值给它的子对象的特性以不同的方式运作。简单的说，就是一句话：允许将子类类型的指针赋值给父类类型的指针。

作用是接口的重用！为了类在继承和派生的时候，保证使用“家谱”中任何一类的实例的某一属性时的正确调用

class Animal:
    def __init__(self, name):  # Constructor of the class
        self.name = name

    def talk(self):  # Abstract method, defined by convention only
        pass #raise NotImplementedError("Subclass must implement abstract method")

class Cat(Animal):
    def talk(self):
        print('Meow!')

class Dog(Animal):
    def talk(self):
        print('Woof! Woof!')

d = Dog("陈荣华")
c = Cat("徐良伟")

d.talk()
c.talk()

class Animal:
    def __init__(self, name):  # Constructor of the class
        self.name = name

    def talk(self):  # Abstract method, defined by convention only
        pass #raise NotImplementedError("Subclass must implement abstract method")

    @staticmethod
    def animal_talk(obj):
        obj.talk()

class Cat(Animal):
    def talk(self):
        print('Meow!')

class Dog(Animal):
    def talk(self):
        print('Woof! Woof!')

d = Dog("陈荣华")
c = Cat("徐良伟")

Animal.animal_talk(c)#接口重用
Animal.animal_talk(d)

静态方法

只是名义上归类管理，实际上在静态方法里访问不了类或实例中的任何属性（不用self参数）