1. 项目
在本节最后一个 electric_car.py 版本中，给 Battery 类添加一个名为
upgrade_battery()的方法。这个方法检查电瓶容量，如果它不是 85，就将它设置为 85。
创建一辆电瓶容量为默认值的电动汽车，调用方法 get_range()，然后对电瓶进行升级，
并再次调用 get_range()。你会看到这辆汽车的续航里程增加了。
2. 代码
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 = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name.title()
def read_odometer(self):
print("This car has " + str(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 = 70):
"""初始化电瓶的属性"""
self.battery_size = battery_size
def describe_battery(self):
"""打印一条描述电瓶容量的消息"""
print("This car has a " + str(self.battery_size) + "-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 == 70:
range = 240
elif self.battery_size == 85:
range = 270
message = "This car can go approximately " + str(range)
message += " miles on a full charge."
print(message)
def upgrade_battery(self): # 添加方法
self.battery_size = 85 # 设置电瓶大小为85
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() # 把电瓶类作为电瓶车的属性
my_BYD = ElectricCar('BYD', '秦', 2012) # 创建默认值电瓶容量的车
my_BYD.battery.get_range() # 调用电瓶的方法
my_BYD.battery.upgrade_battery() # 调用电瓶的方法
my_BYD.battery.get_range()
3. 运行结果
D:python编程：从入门到实践venvScriptspython.exe "D:/python编程：从入门到实践/9-9 电瓶升级.py" This car can go approximately 240 miles on a full charge. This car can go approximately 270 miles on a full charge. Process finished with exit code 0