将实例用作属性

 1 # # coding=GBK
 2 class Car():
 3     """一次模拟汽车的简单尝试"""
 4     
 5     def __init__ (self , make , model , year):
 6         """初始化描述汽车的属性"""
 7         self.make = make
 8         self.model = model
 9         self.year = year
10         self.odometer_reading = 0
11         
12     def get_descriptive_name(self):
13         """返回整洁的描述性信息"""
14         long_name = str(self.year) + ‘ ‘ + self.make + ‘ ‘ +self.model
15         return long_name.title()
16         
17     def read_odometer(self):
18         """打印一条指出汽车里程数的消息"""
19         print("This car has " + str(self.odometer_reading) + " miles on it.")
20         
21     def update_odometer(self , mileage):
22         """
23         将里程表读数设置为指定的值
24         禁止将里程表读数往回调
25         """
26         if mileage >= self.odometer_reading:
27             self.odometer_reading = mileage
28         else:
29             print("You can‘t roll back an ododmeter!")
30   
31 
32     def increment_odometer(self , miles):
33         """将里程表读数增加指定的量"""
34         self.odometer_reading += miles
35         
36 class Battery():
37     """一次模拟电动汽车电瓶的简单尝试"""
38     
39     def __init__ (self , battery_size = 70):
40         """初始化电瓶的属性"""
41         self.battery_size = battery_size
42         
43     def describe_battery(self):
44         """打印一条描述电瓶容量的消息"""
45         print("This car has a " + str(self.battery_size) + "-kwh battery.")
46         
47     def get_range(self):
48         """打印一条消息，指出电瓶的续航里程"""
49         if self.battery_size ==70:
50             range = 240
51         elif self.battery_size == 85:
52             range = 270
53             
54         message = "This car can go approximately " + str(range)
55         message += "miles on a full charge."
56         print(message)
57         
58 class ElectricCar(Car):
59     """电动汽车的独特之处"""
60     
61     def __init__ (self , make , model , year):
62         """
63         电动汽车的独特之处
64         初始化父亲的属性，再初始化电动汽车特有的属性
65         """
66         super(). __init__ (make , model , year)
67         self.battery = Battery()
68         
69     def describe_battery(self):
70         """打印一条描述电瓶容量的消息"""
71         print("This car has a " + str(self.battery_size) + "-kwh battery.")
72         
73 my_tesla = ElectricCar(‘tesla‘ , ‘model s‘ , 2016)
74 print(my_tesla.get_descriptive_name())
75 my_tesla.battery.describe_battery()
76 my_tesla.battery.get_range()