《Python编程从入门到实践》第九章“类”的一个例子代码报错

Question

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.

Answer 1

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.")