python 面向对象之类的继承
python中什么是继承:
新类不必从头编写
新类从现有的类继承，就自动拥有了现有类的所有功能
新类只需要编写现有类缺少的新功能
继承的好处：
复用已有代码
自动拥有了现有类的所有功能
只需要编写缺少的新功能
继承的特点：
子类和父类是is关系
python继承的特点：
总是从某个类继承
不要忘记调用super().init
class People(object):
def __init__(self, name,age):
self.name = name
self.age = age
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)
#继承父类
class Man(People):
pass
m1 = Man("Alin",21)
m1.eat()执行输出：
Alin is eating...
之类还可以自己定义方法
class People(object):
def __init__(self, name,age):
self.name = name
self.age = age
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)
#继承父类
class Man(People):
def go_to_work(self):
print("%s is go_to_work..." % self.name)
m1 = Man("Alin",21)
m1.eat()
m1.go_to_work()执行输出：
Alin is eating...
Alin is go_to_work...
之类可以定义和父类同名的方法
#继承父类
class Man(People):
def go_to_work(self):
print("%s is go_to_work..." % self.name)
def sleep(self):
print("Man is sleeping...")
m1 = Man("Alin",21)
m1.eat()
m1.sleep()执行输出：
Alin is eating...
Man is sleeping...
调用父类方法
#继承父类
class Man(People):
def go_to_work(self):
print("%s is go_to_work..." % self.name)
def sleep(self):
People.sleep(self)
print("Man is sleeping...")
m1 = Man("Alin",21)
m1.eat()
m1.sleep()执行输出：
Alin is eating...
Alin is sleeping...
Man is sleeping...
再写一个类，来继承父类
#继承父类
class Man(People):
def go_to_work(self):
print("%s is go_to_work..." % self.name)
def sleep(self):
People.sleep(self)
print("Man is sleeping...")
class WoMan(People):
def get_birth(self):
print('%s is born a baby...' % self.name)
m1 = Man("Alin",21)
w1 = WoMan("Rose",26)
w1.get_birth()执行输出：
Rose is born a baby...
那么Woman是否可以执行Man里面的方法呢？
#继承父类
class Man(People):
def go_to_work(self):
print("%s is go_to_work..." % self.name)
def sleep(self):
People.sleep(self)
print("Man is sleeping...")
class WoMan(People):
def get_birth(self):
print('%s is born a baby...' % self.name)
m1 = Man("Alin",21)
w1 = WoMan("Rose",26)
w1.get_birth()
w1.go_to_work()执行报错
AttributeError: 'WoMan' object has no attribute 'go_to_work'
子类之间，是无法直接调用的。
现在有了新的需求，Man在实例化的时候，需要多传一个参数,而Woman保持不变。如果直接修改父类，会影响Woman的实例化。那怎么办呢？
需要在Man里面，自己定义参数。
#继承父类
class Man(People):
def __init__(self,name,age,money):
#调用父类的初始化
People.__init__(self,name,age)
#单独定义一个变量
self.money = money
print("%s 一出生,就有 %s money" % (self.name,self.money))
def go_to_work(self):
print("%s is go_to_work..." % self.name)
def sleep(self):
People.sleep(self)
print("Man is sleeping...")
class WoMan(People):
def get_birth(self):
print('%s is born a baby...' % self.name)
m1 = Man("Alin",21,10)
m1.eat()
w1 = WoMan("Rose",26)执行输出：
Alin 一出生,就有 10 money
Alin is eating...
调用父类方法，还有另外一种写法，使用super
#继承父类
class Man(People):
def __init__(self,name,age,money):
#调用父类的初始化
#People.__init__(self,name,age)
super(Man,self).__init__(name,age) #新式类写法那么有什么区别呢?没有区别，效果是一样的。既然这样，为什么还要用super。是因为
super不用写父类的类名，如果有一天，父类的类名，改变了，那么这一行代码就不用更改了，只需要更改继承的父类名就可以了。
推荐使用super继承父类
#class People: 经典类
class People(object): #新式类
def __init__(self, name,age):新式类，必须要加object
super的写法，也是新式类里面的
经典类和新式类，主要是体现在继承上，有些不同。
class People(object): #新式类
def __init__(self, name,age):
self.name = name
self.age = age
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):
def make_friends(self,obj):
print("%s is making friends with %s" % (self.name,obj.name))
#多继承
class Man(People,Relation):
def __init__(self,name,age,money):
#调用父类的初始化
#People.__init__(self,name,age)
super(Man,self).__init__(name,age)
#单独定义一个变量
self.money = money
print("%s 一出生,就有 %s money" % (self.name,self.money))
def go_to_work(self):
print("%s is go_to_work..." % 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("Alin",21,10)
w1 = WoMan("Rose",26)
#执行Relation的方法
m1.make_friends(w1)执行输出：
Alin 一出生,就有 10 money
Alin is making friends with Rose