python继承，判断类型，多态

1、python中继承

如果已经定义了Person类，需要定义新的Student和Teacher类时，可以直接从Person类继承：

class Person(object):
def __init__(self, name, gender):
self.name = name
self.gender = gender

定义Student类时，只需要把额外的属性加上，例如score：

class Student(Person):
def __init__(self, name, gender, score):
super(Student, self).__init__(name, gender)
self.score = score

一定要用 super(Student, self).__init__(name, gender) 去初始化父类，否则，继承自 Person 的 Student 将没有 name 和 gender。

函数super(Student, self)将返回当前类继承的父类，即 Person ，然后调用__init__()方法，注意self参数已在super()中传入，在__init__()中将隐式传递，不需要写出（也不能写）。

实例：

# -*- coding: utf-8 -*-

class Animal(object):
def run(self):
print('Animal is running...')

class Dog(Animal):
def run(self):
print('Dog is running...')

class Cat(Animal):
def run(self):
print('Cat is running...')

def run_twice(animal):
animal.run()
animal.run()

a = Animal()
d = Dog()
c = Cat()

print('a is Animal?', isinstance(a, Animal))
print('a is Dog?', isinstance(a, Dog))
print('a is Cat?', isinstance(a, Cat))

print('d is Animal?', isinstance(d, Animal))
print('d is Dog?', isinstance(d, Dog))
print('d is Cat?', isinstance(d, Cat))

run_twice(c)