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  • 《Python编程从入门到实践》学习笔记<9>:类

      类是对现实生活中一类具有共同特征的事物的抽象,根据类来创建对象被称为实例化,创建类时,类名首字母要大写完整的类如下例所示

    #class声明类,后跟类名,类名首字母需要大写
    class Dog():
        """一次模拟小狗的简单测试"""
        #def定义__init__()方法
        #其中self为类种方法自带形参,指向实例
        def __init__(self, name, age):
             """初始化属性name和age"""
             #self前缀的形参名用于指向实例带入的实参,意为获取存储在形参name中的值
             #这种可以通过实例访问的变量成为属性
             self.name = name
             self.age = age
        
        #定义在类中的函数,也称为方法,方法中的形参self代指实例的参数
        #如果方法中也有不包含在__init__()方法定义的形参,也可以继续跟在self之后
        def sit(self):
             """模拟小狗被命令时蹲下"""
             print(self.name.title() + " is now sitting.")
    
        def roll_over(self):
             """模拟小狗被命令时打滚"""
             print(self.name.title() + " rolled over!")
    
    #实例名 = 类名(),该过程被称为实例化
    #实例化后,实例中的参数将会传入类中等待执行
    my_dog = Dog('willie',6)
    your_dog = Dog('lucy',3)
    
    print("My dog's name is " + my_dog.name.title() + ".")
    print("My dog is " + str(my_dog.age) + " years old.")
    
    #实例化后,调用类中的方法,只需要实例调用类中的方法名即可
    my_dog.sit()
    
    print("
    You dog's name is " + my_dog.name.title() + ".")
    print("You dog is " + str(my_dog.age) + " years old.")
    
    your_dog.sit()
    
    #输出结果如下所示:
    My dog's name is Willie.
    My dog is 6 years old.
    Willie is now sitting.
    
    You dog's name is Willie.
    You dog is 6 years old.
    Lucy is now sitting

      课后习题答案如下:

    #9-1
    #创建类Restaurant
    class Restaurant():
        #定义方法__init__包含三个形参self、restaurant_name和cuisine_type,其中self是每个与类有关的方法自带的形参,也表示实例本身,而其他两个形参则用来传递实参中的数据
        def __init__(self,restaurant_name,cuisine_type):
            #以self为前缀的变量可供类中的所有方法使用,也可以通过类的任何实力来访问这些变量
            #本例中实例one_restaurant将实参中的值传入方法__init__中的形参中,形参再将值保存在被self修饰的两个变量中供给下面代码使用
            self.restaurant_name = restaurant_name
            self.cuisine_type = cuisine_type
        
        #方法describe_restaurant没有新增能其他信息,因此只需要self一个参数,方法open_restaurant同样
        def describe_restaurant(self):
            print(self.restaurant_name + "是一家中国饭馆.")
    
        def open_restaurant(self):
            print("正在营业!")
    
    one_restaurant = Restaurant('菊下楼','四川料理')
    
    print("这家饭馆叫做" + one_restaurant.restaurant_name + ".")
    print(one_restaurant.restaurant_name + "主营" + one_restaurant.cuisine_type + ".")
    
    one_restaurant.describe_restaurant()
    one_restaurant.open_restaurant()
    
    #输出结果如下所示:
    这家饭馆叫做菊下楼.
    菊下楼主营四川料理.
    菊下楼是一家中国饭馆.
    正在营业!
    
    
    
    #9-3
    class User():
        def __init__(self,first_name,last_name,wugong):
            self.first_name = first_name
            self.last_name = last_name
            self.wugong = wugong
    
        def describe_use(self):
            print(self.first_name + self.last_name + "是一名精通" + self.wugong +"的少林高手!")
        def greet_user(self):
            print("少林功夫好耶,真厉害!")
    
    user_name = User('','星星','大力金刚腿')
    user_name.describe_use()
    user_name.greet_user()
    
    #输出结果如下所示:
    周星星是一名精通大力金刚腿的少林高手!
    少林功夫好耶,真厉害!

       修改类中属性值的方式大概有两种,直接修改、通过方法修改属性的值修改,如下所示:

    class Car():
        """一次模拟汽车的简单尝试"""
        def __init__(self,make,model,year):
            """初始化描述汽车的属性"""
            self.make = make
            self.model = model
            self.year = year
            #新增属性odometer_reading,赋默认值0
            #如果形参有值,可以将其放在属性设置时写出,也可以在设置形参时直接写上默认值
            #形参需要通过实例化带入实参的情况下,需要在__init__()中声明
            self.odometer_reading = 0
    
        def get_descriptive_name(self):
            """返回整洁的描述信息"""
            long_name = str(self.year) + ' ' + self.make + ' ' + self.model
            return long_name.title()
    
        def read_odometer(self):
            """打印一条指出汽车里程的信息"""
            print("This car has " + str(self.odometer_reading) + " miles on it.")
    
         #除了直接设置,也可以通过增加方法来修改属性值
        def update_odometer(self,mileage):
            """
            将里程表读书设置为指定的值
            禁止将里程表读数往回调
            """
            if mileage > self.odometer_reading:
                self.odometer_reading = mileage
            else:
                print("You can't roll back an odometer!")
    
        def increment_odometer(self,miles):
            """将里程表的读数增加"""
            self.odometer_reading += miles
    
    
    my_new_car = Car('audi','a4',2016)
    print(my_new_car.get_descriptive_name())
    
    #直接修改属性值,类似关键字实参的设置
    print("---------------直接修改属性值---------------")
    my_new_car.odometer_reading = 23
    my_new_car.read_odometer()
    
    #通过新增方法修改属性值,保留了默认值,在不引用新增方法的情况下,输出无变化
    #用实例引用属性,并赋值
    print("---------------新增方法修改属性值---------------")
    my_new_car.update_odometer(18)
    my_new_car.read_odometer()
    
    #通过新增方法实现属性值的增加
    print("---------------新增方法实现属性值的增加---------------")
    my_new_car.increment_odometer(100)
    my_new_car.read_odometer()

      课后习题答案如下所示:

    #9-4
    class Restaurant():
        def __init__(self,restaurant_name,cuisine_type):
            self.restaurant_name = restaurant_name
            self.cuisine_type = cuisine_type
            self.number_served = 0
    
        def describe_restaurant(self):
            print("这家餐厅叫做" + self.restaurant_name + ",是一家" + self.cuisine_type +"餐厅!")
    
        def open_restaurant(self):
            print("正在营业!")
    
        def number(self):
            print("曾有" + str(self.number_served) + "人在这里就餐")
    
        def set_number_served(self,numbers):
            self.number_served = numbers
    
        def increment_number_served(self,new_number):
            self.number_served += new_number
    
    
    restaurant = Restaurant('菊下楼','川菜')
    
    restaurant.describe_restaurant()
    restaurant.open_restaurant()
    
    restaurant.number_served = 200
    restaurant.number()
    
    restaurant.set_number_served(300)
    restaurant.number()
    
    restaurant.increment_number_served(500)
    restaurant.number()
    
    #输出结果如下所示:
    这家餐厅叫做菊下楼,是一家川菜餐厅!
    正在营业!
    曾有200人在这里就餐
    曾有300人在这里就餐
    曾有800人在这里就餐
    
    
    
    
    #9-5
    class User():
        def __init__(self,first_name,last_name,login_attempts = 0):
            self.first_name = first_name
            self.last_name = last_name
            self.login_attempts = login_attempts
    
        def describe_user(self):
            print(self.first_name.title() + ' ' + self.last_name.title())
    
        def greet_user(self):
            print("Hello,my firend!")
    
        def increment_login_attempts(self):
            self.login_attempts += 1
            print(self.login_attempts)
    
        def reset_login_attempts(self):
            self.login_attempts = 0
            print(self.login_attempts)
    
    my_firend = User('jimi','lee')
    my_firend.describe_user()
    my_firend.greet_user()
    my_firend.increment_login_attempts()
    my_firend.reset_login_attempts()
    
    #输出结果如下所示:
    Jimi Lee
    Hello,my firend!
    1
    0

      继承是面向对象编程的概念之一,通过类的调用,让其中一个类获得另一个类的部分或全部特征的一种方式。继承可以使得子类别具有父类别的各种属性和方法,如下例所示:

    #给子类定义属性和方法
    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.odmeter_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.odmeter_reading) + " miles on it.")
    
        def update_odometer(self,mileage):
            if mileage >= self.odmeter_reading:
                self.odmeter_reading = mileage
            else:
                print("You can't roll back an odometer!")
    
        def increment_odometer(self,miles):
            self.odmeter_reading += miles
    
    #定义类ElectricCar,括号中是继承的父类Car
    class ElectricCar(Car):
        """Represent aspects of a car,specific toelectric vehicles."""
        def __init__(self,make,model,year):
            """
            电动汽车的独特之处
            初始化父类的属性,在初始化为电动汽车特有的属性
            """
            #函数super()用于调整父类和子类的继承问题,尤其是多类继承的时候,super()可以声明调用类的名字,单类中可以不用声明
            #此处通过调用父类中的__init__()方法,让子类ElectricCar中的实例包含父类实例的所有属性
            super().__init__(make,model,year)
            添加了子类的新属性self.battery_size = 70,只存在于子类ElectricCar中,父类没有该属性
            self.battery_size = 70
    
        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.")
    
    my_tesla = ElectricCar('tesla','model s',2016)
    print(my_tesla.get_descriptive_name())
    my_tesla.describe_battery()
    
    #输出结果如下:
    2016 Tesla Model S
    This car has a 70-kWh battery.

      子类继承父类以后,也可以单独给子类定义属性和方法,此时该属性或者方法独属于子类,与父类无关,如下所示:

    #给子类定义属性和方法
    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.odmeter_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.odmeter_reading) + " miles on it.")
    
        def update_odometer(self,mileage):
            if mileage >= self.odmeter_reading:
                self.odmeter_reading = mileage
            else:
                print("You can't roll back an odometer!")
    
        def increment_odometer(self,miles):
            self.odmeter_reading += miles
    
    #定义类ElectricCar,括号中是继承的父类Car
    class ElectricCar(Car):
        """Represent aspects of a car,specific toelectric vehicles."""
        def __init__(self,make,model,year):
            """
            电动汽车的独特之处
            初始化父类的属性,在初始化为电动汽车特有的属性
            """
            #函数super()用于调整父类和子类的继承问题,尤其是多类继承的时候,super()可以声明调用类的名字,单类中可以不用声明
            #此处通过调用父类中的__init__()方法,让子类ElectricCar中的实例包含父类实例的所有属性
            super().__init__(make,model,year)
            #添加了子类的新属性self.battery_size = 70,只存在于子类ElectricCar中,父类没有该属性
            self.battery_size = 70
    
        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.")
        
        #重写父类的方法,可在子类中定义一个与父类中需要重写的方法同名的方法即可
        def get_descriptive_name(self):
            long_name = str(self.year)  + ' ' + self.model + ' ' + self.make + " (原结果为:2016 Tesla Model S)"
            return long_name.title()
            
    my_tesla = ElectricCar('tesla','model s',2016)
    #此处实例调用了get_descriptive_name()方法,因此直接输出了方法的返回值
    print(my_tesla.get_descriptive_name()) my_tesla.describe_battery() #输出结果如下: 2016 Model S Tesla (原结果为:2016 Tesla Model S) This car has a 70-kWh battery.

      此外,除了在子类对继承的父类进行操作,还可以将实例用作属性,如下所示:

    #将实例用做属性
    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.odmeter_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.odmeter_reading) + " miles on it.")
    
        def update_odometer(self,mileage):
            if mileage >= self.odmeter_reading:
                self.odmeter_reading = mileage
            else:
                print("You can't roll back an odometer!")
    
        def increment_odometer(self,miles):
            self.odmeter_reading += miles
    
    
    #定义一个没有继承的新类,包含形参battery_size,并赋默认值70
    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)
    
    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,再初始化为电动汽车特有的属性
            """
            super().__init__(make,model,year)
            #添加新的属性self.battery,将类Battery实例化为Battery()(由于没有规定参数,因此为空,Battery类中有默认值70)
            self.battery = Battery()
    
    my_tesla = ElectricCar('tesla','model s',2016)
    
    print(my_tesla.get_descriptive_name())
    
    #访问作为属性的实例,实例.属性.方法
    my_tesla.battery.describe_battery()
    my_tesla.battery.get_range() 
    
    #输出结果如下所示:
    2016 Tesla Model S
    This car has a 70-kWh battery.
    This car can go approximately 240 miles on a full charge.

      课后习题答案如下所示:

    #9-6
    class Restaurant():
        def __init__(self,restaurant_name,cuisine_type):
            self.restaurant_name = restaurant_name
            self.cuisine_type = cuisine_type
            self.number_served = 0
    
        def describe_restaurant(self):
            print("这家餐厅叫做" + self.restaurant_name + ",是一家" + self.cuisine_type +"餐厅!")
    
        def open_restaurant(self):
            print("正在营业!")
    
        def number(self):
            print("曾有" + str(self.number_served) + "人在这里就餐")
    
        def set_number_served(self,numbers):
            self.number_served = numbers
    
        def increment_number_served(self,new_number):
            self.number_served += new_number
    
    #定义子类IceCreanStand继承父类Restaurant
    class IceCreanStand(Restaurant):
        #定义方法__init__,同时包含父类形参restaurant_name,cuisine_type
        def __init__(self,restaurant_name,cuisine_type):
            #使用super()函数,将子类部分形参与父类形参关联,此时子类被关联形参可以使用父类方法
            super().__init__(restaurant_name,cuisine_type)
            #定义子类专属形参flavors,赋值为空列表,该形参不可使用使用
            self.flavors = []
    
        #定义方法flavors_type,该方法单独实现子类需求
        def flavors_type(self):
            while True:
                ice_cream = input("输入冰淇淋的口味:
    ")
                if ice_cream == 'quit':
                    break
                else:
                    self.flavors.append(ice_cream)
            print("这里的冰淇淋口味有:")
            for ice in self.flavors:
                print("	-" + ice)
    
    restaurant = IceCreanStand('菊下楼','川菜')
    restaurant.describe_restaurant()
    restaurant.open_restaurant()
    restaurant.number()
    restaurant.flavors_type()
    
    #输出结果如下所示:
    这家餐厅叫做菊下楼,是一家川菜餐厅!
    正在营业!
    曾有0人在这里就餐
    输入冰淇淋的口味:
    草莓
    输入冰淇淋的口味:
    香蕉
    输入冰淇淋的口味:
    苹果
    输入冰淇淋的口味:
    荔枝
    输入冰淇淋的口味:
    quit
    这里的冰淇淋口味有:
        -草莓
        -香蕉
        -苹果
        -荔枝
    
    
    
    
    
    
        
    #9-7
    #创建父类User
    class User():
        #创建__init__()方法初始化属性
        def __init__(self, first_name, last_name, login_attempts=0):
            self.first_name = first_name
            self.last_name = last_name
            self.login_attempts = login_attempts
    
        def describe_user(self):
            print(self.first_name.title() + ' ' + self.last_name.title())
    
        def greet_user(self):
            print("Hello,my firend!")
    
        def increment_login_attempts(self):
            self.login_attempts += 1
            print(self.login_attempts)
    
        def reset_login_attempts(self):
            self.login_attempts = 0
            print(self.login_attempts)
    
    #创建子类Admin继承父类User
    class Admin(User):irst_name, last_name, login_attempts
        #定义方法__init__,包含父类变量
        def __init__(self, first_name, last_name, login_attempts):
            #使用super()方法,让子类变量跟父类变量关联,使子类实例能够包含父类的属性
            super().__init__(first_name, last_name, login_attempts)
            self.privileges = ['可以删除', '可以新增', '可以修改']
        #创建方法show_privileges,使用父类属性进行判断,并更具判断结果,输出类属性的值
        def show_privileges(self):
            if self.login_attempts == 0:
                print("没有特权!")
            elif self.login_attempts == 1:
                print(self.first_name.title() + ' ' + self.last_name.title() +
                      ",你可以试试" + self.privileges[0] + "操作!")
            elif self.login_attempts == 2:
                print(self.first_name.title() + ' ' + self.last_name.title() +
                      ",你可以试试" + self.privileges[1] + "操作!")
            elif self.login_attempts == 3:
                print(self.first_name.title() + ' ' + self.last_name.title() +
                      ",你可以试试" + self.privileges[2] + "操作!")
    
    #实例包含父类实参,还包含子类实参
    my_firend = Admin('jimi', 'lee', 1)
    my_firend.describe_user()
    my_firend.greet_user()
    my_firend.show_privileges()
    
    #输出结果如下:
    Jimi Lee
    Hello,my firend!
    Jimi Lee,你可以试试可以删除操作!
    
    #输出结果如下所示:
    Jimi Lee
    Hello,my firend!
    你没有特权!
    
    
    
    
    
    
    
    #9-8
    class User():
        def __init__(self, first_name, last_name, login_attempts=0):
            self.first_name = first_name
            self.last_name = last_name
            self.login_attempts = login_attempts
    
        def describe_user(self):
            print(self.first_name.title() + ' ' + self.last_name.title())
    
        def greet_user(self):
            print("Hello,my firend!")
    
    #定义新的类Privileges,只有属性self.privileges,赋值列表
    class Privileges():
        def __init__(self,privileges = ['可以删除', '可以新增', '可以修改']):
            self.privileges = privileges
    
        def show_privileges(self):
            print("你没有特权!")
    
    class Admin(User):
        def __init__(self, first_name, last_name, login_attempts):
            super().__init__(first_name, last_name, login_attempts)
            #将类Privileges实例化后用作属性
            self.privilege = Privileges()
    
    my_firend = Admin('jimi', 'lee',1)
    my_firend.describe_user()
    my_firend.greet_user()
    #引用实例属性化的方法时,需注意格式为实例.属性.方法
    my_firend.privilege.show_privileges()
    
    #输出结果如下所示:
    Jimi Lee
    Hello,my firend!
    你没有特权!
    
    
    
    
    
    
    #9-9
    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.odmeter_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.odmeter_reading) + " miles on it.")
    
        def update_odometer(self,mileage):
            if mileage >= self.odmeter_reading:
                self.odmeter_reading = mileage
            else:
                print("You can't roll back an odometer!")
    
        def increment_odometer(self,miles):
            self.odmeter_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):
            #此处判断,出现!=后,下文需用=,用==会报错,不知道为什么,先记下来!
            if self.battery_size != 85:
                self.battery_size = 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,再初始化为电动汽车特有的属性
            """
            super().__init__(make,model,year)
            self.battery = Battery()
    
    my_tesla = ElectricCar('tesla','model s',2016)
    
    print(my_tesla.get_descriptive_name())
    my_tesla.battery.get_range()
    my_tesla.battery.upgrade_battery()
    my_tesla.battery.get_range()
    
    #输出结果如下所示:
    2016 Tesla Model S
    This car can go approximately 240 miles on a full charge.
    This car can go approximately 270 miles on a full charge.

      类的导入分为导入单个类,在模块中存储多个类和导入整个模块,具体实例如下所示:

    #导入单个类
    ---------------------------------------------------------------------------------
    test1.py
    ---------------------------------------------------------------------------------
    """一个可用于表示汽车的类"""
    
    class Car():
        """一次模拟汽车的简单尝试"""
        def __init__(self,make,model,year):
            """初始化描述汽车的属性"""
            self.make = make
            self.model = model
            self.year = year
            self.odometer_reading = 0
    
        def get_descriptive_name(self):
            """返回整洁的描述性名称"""
            long_name = str(self.year) + ' ' + self.make + ' '+ self.model
            return  long_name
    
        def read_odometer(self):
            """打印一条信息,指出汽车的里程"""
    
            print("This car has " + str(self.odometer_reading) + " miles on it.")
    
        def update_odometer(selfself,mileage):
            """
            将里程表读数设置为指定值
            拒绝里程表往回拨
            """
            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
    ---------------------------------------------------------------------------------
    test2.py
    ---------------------------------------------------------------------------------
    #在其他程序中调用模块中的类,需要声明,格式如下
    #引用模块语句,打开文件test1,调用类Car
    from test1 import Car
    
    my_new_car = Car('audi','a4',2016)
    print(my_new_car.get_descriptive_name())
    
    my_new_car.odometer_reading = 23
    my_new_car.read_odometer()
    
    my_new_car = Car('audi','a4',2016)
    print(my_new_car.get_descriptive_name())
    
    my_new_car.odometer_reading = 23
    my_new_car.read_odometer()
    
    #输出结果如下所示:
    2016 audi a4
    This car has 23 miles on it.
    
    
    
    
    
    
    #在一个模块中存储多个类
    ---------------------------------------------------------------------------------
    test1.py
    ---------------------------------------------------------------------------------
    """一个可用于表示汽车的类"""
    
    class Car():
        """一次模拟汽车的简单尝试"""
        def __init__(self,make,model,year):
            """初始化描述汽车的属性"""
            self.make = make
            self.model = model
            self.year = year
            self.odometer_reading = 0
    
        def get_descriptive_name(self):
            """返回整洁的描述性名称"""
            long_name = str(self.year) + ' ' + self.make + ' '+ self.model
            return  long_name
    
        def read_odometer(self):
            """打印一条信息,指出汽车的里程"""
    
            print("This car has " + str(self.odometer_reading) + " miles on it.")
    
        def update_odometer(selfself,mileage):
            """
            将里程表读数设置为指定值
            拒绝里程表往回拨
            """
            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
    
    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):
            """打印一条描述电瓶续航里程的消息"""
            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)
    
    class  ElectricCar(Car):
        """模拟电动汽车的独特之处"""
        def __init__(self,make,model,year):
            """
            初始化父类的属性,在初始化电动汽车特有的属性
            """
            super().__init__(make,model,year)
            self.battery = Battery()
    ---------------------------------------------------------------------------------
    test3.py
    ---------------------------------------------------------------------------------
    #一个模块多个类的调用,只需注明调用的类名即可
    #引用模块语句,打开文件test1,调用类ElectricCar
    from test1 import ElectricCar
    
    my_tesla = ElectricCar('tesla','model s',2016)
    
    print(my_tesla.get_descriptive_name())
    my_tesla.battery.describe_battery()
    my_tesla.battery.get_range()
    ---------------------------------------------------------------------------------
    test4.py
    ---------------------------------------------------------------------------------
    #导入整个模块
    #先导入模块
    import test1
    
    #导入模块后,调用类只需要实例化的时候,用句点的方法引用,通过模块来调用类
    my_beetly = test1.Car('volkswagen','beetle',2016)
    #调用类以后,在调用类中的方法
    print(my_beetly.get_descriptive_name())
    
    my_tesla = test1.ElectricCar('tesla','roadster',2016)
    print(my_tesla.get_descriptive_name())
    
    
    #输出结果如下所示:
    #test3
    2016 tesla model s
    This car has a 70-kWh battery.
    This car can go approximately 240 miles on a full charge.
    #test4
    2016 volkswagen beetle
    2016 tesla roadster 
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  • 原文地址:https://www.cnblogs.com/a404790696/p/11049523.html
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