P9-类

class Dog:
    """A simple attempt to model a dog."""  
  
    def __init__(self, name, age):
        """Initialize name and age attributes."""
        self.name = name
        self.age = age
        
    def sit(self):
        """Simulate a dog sitting in response to a command."""
        print(f"{self.name} is now sitting.")

    def roll_over(self):
        """Simulate rolling over in response to a command."""
        print(f"{self.name} rolled over!")

my_dog = Dog('Willie', 6)
your_dog = Dog('Lucy', 3)

print(f"My dog's name is {my_dog.name}.")
print(f"My dog is {my_dog.age} years old.")
my_dog.sit()

print(f"\nYour dog's name is {your_dog.name}.")
print(f"Your dog is {your_dog.age} years old.")
your_dog.sit()

 

class 定义一个类  _init_(self,xxx,xxxx)   _init_ 构造方法   构造方法的self不用传 自动传入，相当于Java的this指向实例的本身

self中的属性就是类的属性

class Car:
    """A simple attempt to represent a car."""

    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 = 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_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 ElectricCar(Car):
    """Represent aspects of a car, specific to electric vehicles."""
    
    def __init__(self, make, model, year):
        """
        Initialize attributes of the parent class.
        Then initialize attributes specific to an electric car.
        """
        super().__init__(make, model, year)
        self.battery_size = 75

    def describe_battery(self):
        """Print a statement describing the battery size."""
        print(f"This car has a {self.battery_size}-kWh battery.")

my_tesla = ElectricCar('tesla', 'model s', 2019)
print(my_tesla.get_descriptive_name())
my_tesla.describe_battery()

 

子类和父类必须在同一个文件中，且位于子类前面

在子类的 _init_中调用super（）

from car import Car

my_new_car = Car('audi', 'a4', 2019)
print(my_new_car.get_descriptive_name())

my_new_car.odometer_reading = 23
my_new_car.read_odometer()

 

导入类

import car

my_beetle = car.Car('volkswagen', 'beetle', 2019)
print(my_beetle.get_descriptive_name())

my_tesla = car.ElectricCar('tesla', 'roadster', 2019)
print(my_tesla.get_descriptive_name())

 

导入整个模块