【Python 第50课】 面向对象（4）

弹星者

1. class Vehicle:
   
2.     def __init__(self, speed):
   
3.         self.speed = speed
   
4. 
   
5.     def drive(self, distance):
   
6.         print 'need %f hour(s)' % (distance / self.speed)
   
7. 
   
8. class Bike(Vehicle):
   
9.     pass
   
10. 
    
11. class Car(Vehicle):
    
12.     def __init__(self, speed, fuel):
    
13.         Vehicle.__init__(self, speed)
    
14.         self.fuel = fuel
    
15. 
    
16.     def drive(self, distance):
    
17.         Vehicle.drive(self, distance)
    
18.         print 'need %f fuels' % (distance * self.fuel)
    
19. 
    
20. b = Bike(15.0)
    
21. c = Car(80.0, 0.012)
    
22. b.drive(100.0)
    
23. c.drive(100.0)
    
24. 
    
25. d=Car(80,None)
    
26. d.Vehicle.drive(100)
    
27. 
    
28. #下面是运行报错
    
29. '''
    
30. need 6.666667 hour(s)
    
31. need 1.250000 hour(s)
    
32. need 1.200000 fuels
    
33. <blockquote>Traceback (most recent call last):

复制代码

在crossin老师代码的最后添加了两行，想尝试一下子类调用父类里的函数，然而运行的时候报错了，这个错误为什么呀（代码复制的时候没复制好，在楼下重发一个

弹星者

1. class Vehicle:
   
2.     def __init__(self, speed):
   
3.         self.speed = speed
   
4. 
   
5.     def drive(self, distance):
   
6.         print 'need %f hour(s)' % (distance / self.speed)
   
7. 
   
8. class Bike(Vehicle):
   
9.     pass
   
10. 
    
11. class Car(Vehicle):
    
12.     def __init__(self, speed, fuel):
    
13.         Vehicle.__init__(self, speed)
    
14.         self.fuel = fuel
    
15. 
    
16.     def drive(self, distance):
    
17.         Vehicle.drive(self, distance)
    
18.         print 'need %f fuels' % (distance * self.fuel)
    
19. 
    
20. b = Bike(15.0)
    
21. c = Car(80.0, 0.012)
    
22. b.drive(100.0)
    
23. c.drive(100.0)
    
24. 
    
25. d=Car(80,None)
    
26. d.Vehicle.drive(100)
    
27. 
    
28. #下面是报错
    
29. '''
    
30. need 6.666667 hour(s)
    
31. need 1.250000 hour(s)
    
32. need 1.200000 fuels
    
33. Traceback (most recent call last):
    
34.   File "123.py", line 26, in <module>
    
35.     d.Vehicle.drive(100)
    
36. AttributeError: Car instance has no attribute 'Vehicle'
    
37. '''

复制代码

在crossin老师代码的最后添加了两行，想尝试一下子类调用父类里的函数，然而运行的时候报错了，这个错误为什么呀