[已解决]类的方法有个问题不明吧

ilsoviet1917

1. class Car():
   
2.    
   
3.     def __init__(self, make, model, year):
   
4.         self.make = make
   
5.         self.model = model
   
6.         self.year = year
   
7.         self.odometer_reading = 0
   
8.    
   
9.     def get_descriptive_name(self):
   
10.         long_name = str(self.year) + ' ' + self.make + ' ' + self.year
    
11.         return long_name.title()
    
12.    
    
13.     def read_odometer(self):
    
14.         print("This car has " + str(self.odometer_reading) + " miles on it.")
    
15.    
    
16.     def update_odometer(self, mileage):
    
17.         if mileage >= self.odometer_reading:
    
18.             self.odometer_reading = mileage
    
19.         else:
    
20.             print("You can't roll back an odometer!")
    
21.    
    
22.     def increment_odometer(self, miles):
    
23.         self.odometer_reading += miles
    
24. 
    
25. class Battery():
    
26.     def __init__(self, battery_size = 70):
    
27.         self.battery_size = battery_size
    
28. 
    
29.     def describe_battery(self):
    
30.         print("This car has a " + str(self.battery_size) + "-Kwh battery.")
    
31. 
    
32.     def upgrade_battery(self):
    
33.         if self.battery_size != 85:
    
34.             self.battery_size = 85
    
35. 
    
36.     def get_range(self):
    
37.         if self.battery_size == 70:
    
38.             range = 240
    
39.         elif self.battery_size == 85:
    
40.             range = 270
    
41.         message = "This car can go approxximately " + str(range)
    
42.         message += " miles on a full charge."
    
43.         print(message)
    
44.         self.upgrade_battery()
    
45. 
    
46. class ElectricCar(Car):
    
47.     def __init__(self, make, model, year):
    
48.         super().__init__(make, model, year)
    
49.         self.battery = Battery()
    
50. 
    
51. 
    
52. my_tesla = ElectricCar('tesla', 'model s', '2016')
    
53. print(my_tesla.get_descriptive_name())
    
54. 
    
55. my_tesla.battery.describe_battery()
    
56. my_tesla.battery.get_range()
    
57. my_tesla.battery.get_range()

复制代码

self.upgrade_battery()
44行，按说程序不都是从上向下执行吗?为什么这一行执行完后battery_size还能从70变成85？

最佳答案

月排行榜 / 总排行榜

zltzlt

2020-2-9 14:44:43

调用 get_range() --> 执行到 self.upgrade_battery() --> 如果 self.battery_size 不等于 85，则设置其为 85

跳转到最佳答案楼层

zltzlt

调用 get_range() --> 执行到 self.upgrade_battery() --> 如果 self.battery_size 不等于 85，则设置其为 85