[Python知识库]Python类的知识

关于Python的类，首先定义一个Car类：?

#定义一个Car类
class Car:
    def __init__(self,make,model,year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
    def get_descriptive(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_odemeter(self,mileage):
        if mileage >= self.odometer_reading:
            self.odometer_reading = mileage
        else:
            print("You can't roll back an odometer!")

    def increment_odermeter(self,miles):
        self.odometer_reading += miles

然后以Car类为父类，定义一个子类ElectricCar，并使用super().__init__()，继承父类，并能够调用父类Car的方法,并添加属性battery：

定义一个Car的子类：ElectricCar类
class ElectricCar(Car):
    #初始化父类Car的属性
    def __init__(self,make,model,year):
        super().__init__(make,model,year)
        self.battery_size = 75
        self.battery = Battery()

在实现子类和父类之后，可在定义一个类，将其作为ElectricCar类的一个属性，实现将实例用作属性：

#定义一个Battery类作为实例，将其作为属性
class Battery():
    def __init__(self,battery_size=75):
        self.battery_size = battery_size

    def describe_battery(self):
        print(f"This car has a {self.battery_size} kwh battery.")

调用：

创建一个实例，并通过ElectricCar类调用Battery，打印出电动汽车的电瓶里程：

mycar = ElectricCar('tesla','model S',2019)
print(mycar.get_descriptive())
mycar.battery.battery_size=80
mycar.battery.describe_battery()

运行结果如下：

?