创建类

#!/usr/bin/env python

# --*-- encoding:utf-8 --*--

class Dog():

"""一次模拟小狗的简单尝试"""

def __init__(self,name,age):

"""初始化属性name和age"""

self.name = name

self.age = age

def sit(self):

"""模拟小狗别命令时蹲下"""

print(self.name.title() + " is now sitting.")

def roll_over(self):

"""模拟小狗被命中时打滚"""

print(self.name.title() + " rolled over!")

my_dog = Dog('willie',6)

your_dog = Dog('lucy',3)

# print("My dog's name is " + my_dog.name.title() + ".")

# print("My dog is " + str(my_dog.age) + " years old.")

my_dog.sit()

print("\nYour dog's name is " + your_dog.name.title() + ".")

print("Your dog is " + str(your_dog.age) + " years old.")

your_dog.sit()

给属性指定默认值

#!/usr/bin/env python

# --*-- encoding:utf-8 --*--

class Car():

def __init__(self,make,model,year):

"""模拟汽车的的属性"""

self.make = make

self.model = model

self.year = year

self.odometer_reading = 0

def get_descriptive_name(self):

"""返回整洁的描述性信息"""

long_name = str(self.year) + ' ' + self.make + ' ' + self.model

return long_name.title()

def read_odometer(self):

"""打印一条指出汽车里程的消息"""

print("This car has " + str(self.odometer_reading) + " miles on it.")

my_new_car = Car('audi','a3',2016)

print(my_new_car.get_descriptive_name())

my_new_car.read_odometer()

修改属性的值：

1：直接修改属性的值

#!/usr/bin/env python#--*-- encoding:utf-8 --*--

classCar():def __init__(self,make,model,year):"""模拟汽车的的属性"""self.make=make

self.model=model

self.year=year

self.odometer_reading=0defget_descriptive_name(self):"""返回整洁的描述性信息"""long_name= str(self.year) + ' ' + self.make + ' ' +self.modelreturnlong_name.title()defread_odometer(self):"""打印一条指出汽车里程的消息"""

print("This car has" + str(self.odometer_reading) + "miles on it.")

my_new_car= Car('audi','a3',2016)print(my_new_car.get_descriptive_name())

my_new_car.odometer_reading= 23my_new_car.read_odometer()

直接修改属性的值

2：通过方法修改属性的值

#!/usr/bin/env python#--*-- encoding:utf-8 --*--

classCar():def __init__(self,make,model,year):"""模拟汽车的的属性"""self.make=make

self.model=model

self.year=year

self.odometer_reading=0defget_descriptive_name(self):"""返回整洁的描述性信息"""long_name= str(self.year) + ' ' + self.make + ' ' +self.modelreturnlong_name.title()defread_odometer(self):"""打印一条指出汽车里程的消息"""

print("This car has" + str(self.odometer_reading) + "miles on it.")defupdate_odometer(self,mileage):"""将里程表读书设置为指定的值"""self.odometer_reading=mileage

my_new_car= Car('audi','a3',2016)print(my_new_car.get_descriptive_name())

my_new_car.update_odometer(23)

my_new_car.read_odometer()

通过方法修改属性值

#!/usr/bin/env python#--*-- encoding:utf-8 --*--

classCar():def __init__(self,make,model,year):"""模拟汽车的的属性"""self.make=make

self.model=model

self.year=year

self.odometer_reading= 25

defget_descriptive_name(self):"""返回整洁的描述性信息"""long_name= str(self.year) + ' ' + self.make + ' ' +self.modelreturnlong_name.title()defread_odometer(self):"""打印一条指出汽车里程的消息"""

print("This car has" + str(self.odometer_reading) + "miles on it.")defupdate_odometer(self,mileage):"""将里程表读数设置为指定的值

禁止将里程表读数往回调"""

if mileage >=self.odometer_reading:

self.odometer_reading=mileageelse:print("You can't roll back an odometer!")

my_new_car= Car('audi','a3',2016)print(my_new_car.get_descriptive_name())

my_new_car.update_odometer(23)

my_new_car.read_odometer()

执行结果：2016Audi A3

You can't roll back an odometer!

This car has 25 miles on it.

扩展

3：通过方法对属性的值进行递增

继承

如果编写的类是另一个现成类的特殊版本，可使用继承。一个类集成另一个类时，它将自动获得另一个类的所有属性和方法；原有的类称为父类，而新类称为子类。

子类继承了其父类的所有属性和方法，同时还可以定义自己的属性和方法。