python - 了解类以及导致此属性错误的原因

Question

我对编码非常陌生，并且已经开始学习如何使用 Python。几天前我开始学习课程，我对它们有点困惑，但我练习得越多，我开始了解的越多。因此，为了练习，我尝试执行此代码，但不断收到属性错误：

>>> class Hero:
     def __init__(self):
         self.health = 100
     def eat (self, food):
         if food == ham:
             print 'Bob has gained health!'
             self.health+=self.HealthBonus
         elif food == poison:
             print 'Oh no! Bob has taken damage!'
             self.health-=self.HealthDown

>>> class Ham:
     def __init__ (self):
         self.name = 'ham'
         self.HealthBonus = 10

>>> class Poison:
     def __init__ (self):
         self.name = 'poison'
         self.HealthDown = 20

>>> bob=Hero()
>>> ham=Ham()
>>> poison=Poison()
>>> bob.eat(ham)
Bob has gained health!
Traceback (most recent call last):
  File "<pyshell#9>", line 1, in <module>
    bob.eat(ham)
  File "<pyshell#1>", line 7, in eat
    self.health+=self.HealthBonus
AttributeError: Hero instance has no attribute 'HealthBonus'

有人可以帮我确定此属性错误的原因吗？

标签： pythonpython-2.7

Answer 1

你的问题出在这里：

>>> class Hero:
     def __init__(self):
         self.health = 100
     def eat (self, food):
         if food == ham:
             print 'Bob has gained health!'
             self.health+=self.HealthBonus
         elif food == poison:
             print 'Oh no! Bob has taken damage!'
             self.health-=self.HealthDown

您有“self.HealthBonus”，而 self 是指拥有被调用的当前方法（函数）的类的实例。Eat 归Hero类所有。当您将食物变量传递给 eat 方法时，食物是具有健康奖励的东西，而不是英雄。改成这样：

>>> class Hero:
     def __init__(self):
         self.health = 100
     def eat (self, food):
         if food == ham:
             print 'Bob has gained health!'
             self.health+=food.HealthBonus
         elif food == poison:
             print 'Oh no! Bob has taken damage!'
             self.health-=food.HealthDown