9-9 电瓶升级_电瓶升级9-9

9-9 电瓶升级 ：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。

class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
        self.gas_tank_reading = 1000
 
    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
 
    def fill_gas_tank(self):
        print("The gas tank of the car is :" +str(self.gas_tank_reading)+'!')
 
class Battery():
    def __init__(self, battery_size = 70):
        self.battery_size = battery_size
 
    def describe_battery(self):
        print("This car has a "+str(self.battery_size)+"-kWh battery.")
 
    def get_range (self):
        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):
        if self.battery_size !=85:
            self.battery_size = 85        
 
class ElectricCar(Car):
    def __init__(self, make, model, year):
 
        super().__init__(make, model, year)
        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()
'
运行
运行

运行结果：