class Car():
    """一次模拟汽车的简单尝试"""

    def __init__(self, make, model, year):
        """初始化描述汽车属性"""
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0

    def get_descriptive_name(self):
        """返回整洁的描述性信息"""
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()

    def update_odometer(self, mileage):
        """
        将里程表读数设置为指定的值
        禁止将里程表读数回调
        """
        if mileage >= self.odometer_reading:
            self.odometer_reading = mileage
        else:
            print("You can't roll back an odometer!")

    def increment_odometer(self, miles):
        """将里程表读数增加指定的量"""
        self.odometer_reading += miles

    def read_odometer(self):
        """
        打印一条指出汽车里程的消息
        """
        print("This car has " + str(self.odometer_reading) + " miles on it.")

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):
        """更新电瓶"""
        if self.battery_size != 85:
            self.battery_size = 85

class ElectricCar(Car):
    """表示汽车的各个方面，特别是电动汽车"""

    def __init__(self, make, model, year):
        """初始化父类属性，再初始化电动汽车特有的属性"""
        super().__init__(make, model, year) # 让Python调用ElectricCar的父类的方法__init__()
        self.battery = Battery()



my_tesla = ElectricCar('tesla', 'model_s', 2016)
print(my_tesla.get_descriptive_name())
my_tesla.battery.describe_battery()
my_tesla.battery.get_range()
my_tesla.battery.upgrade_battery()
my_tesla.battery.get_range()

2016 Tesla Model_S
This car has a 70-kWh battery.
This car can go approximately 240 miles on a full charge.
This car can go approximately 270 miles on a full charge.