《Python编程从入门到实践》第九章“类”的一个例子代码报错
问题遇到的现象和发生背景
《Python编程从入门到实践》第九章“类” 9.3.4 将实例用作属性
问题相关代码，请勿粘贴截图
class Car:
"""一次模拟汽车的简单尝试。"""
def __init__(self, make, model, year):
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0
def get_descriptive_name(self):
long_name = f"{self.year} {self.make} {self.model}"
return long_name.title()
def read_odometer(self):
print(f"This car has {self.odometer_reading} miles on it.")
def update_odometer(self, mileage):
if mileage >= self.odometer_reading:
self.odometer_reading = mileage
else:
print("You can't roll back an odometer!")
def increment_odometer(self, miles):
self.odometer_reading += miles
class Battery:
"""一次模拟电动汽车电瓶的简单尝试。"""
def __init__(self, battery_size=75):
"""初始化电瓶的属性。"""
self.battery = battery_size
def describe_battery(self):
"""打印一条描述电瓶容量的消息。"""
print(f"This car has a {self.battery}-kwh battery.")
def get_range(self):
"""打印一条消息，指出电瓶的续航里程。"""
if self.battery_size == 75:
range = 260
elif self.battery_size == 100:
range = 315
print(f"This car can go about {range} miles on a full charge.")
class ElectricCar(Car):
"""电动汽车的独特之处。"""
def __init__(self, make, model, year):
"""
初始化父类的属性。
再初始化电动汽车特有的属性。
"""
super().__init__(make, model, year)
self.battery = Battery()
my_tesla = ElectricCar('tesla', 'model s', 2019)
print(my_tesla.get_descriptive_name())
my_tesla.battery.describe_battery()
my_tesla.battery.get_range()
运行结果及报错内容
2019 Tesla Model S
This car has a 75-kwh battery.
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-1-a646f04f8a96> in <module>
59
60 my_tesla.battery.describe_battery()
---> 61 my_tesla.battery.get_range()
<ipython-input-1-a646f04f8a96> in get_range(self)
37 def get_range(self):
38 """打印一条消息，指出电瓶的续航里程。"""
---> 39 if self.battery_size == 75:
40 range = 260
41 elif self.battery_size == 100:
AttributeError: 'Battery' object has no attribute 'battery_size'
我的解答思路和尝试过的方法
我想要达到的结果
2019 Tesla Model S
This car has a 75-kwh battery.
This car can go about 260 miles on a full charge.
self.battery_size
改为：
self.battery
init()方法中初始化了battery属性，后面操作，直接用battery这个属性。
class Battery:
def __init__(self, battery_size=75):
"""初始化电瓶的属性。"""
self.battery = battery_size
def get_range(self):
"""打印一条消息，指出电瓶的续航里程。"""
if self.battery == 75:
range = 260
elif self.battery == 100:
range = 315
print(f"This car can go about {range} miles on a full charge.")
Battery 类中 __init__中定义的是 self.battery
你 def get_range(self):中用的却是 self.battery_size
你 def get_range(self):中 self.battery_size 改成self.battery即可
def get_range(self):
"""打印一条消息，指出电瓶的续航里程。"""
if self.battery == 75:
range = 260
elif self.battery == 100:
range = 315
print(f"This car can go about {range} miles on a full charge.")
您好，我是有问必答小助手，您的问题已经有小伙伴帮您解答，感谢您对有问必答的支持与关注！如有帮助，请点击我的回答下方的【采纳该答案】按钮帮忙采纳下，谢谢!
PS：问答VIP年卡 【限时加赠：IT技术图书免费领】，了解详情>>> https://vip.csdn.net/askvip?utm_source=1146287632