十个简单的Python类的例子
涵盖了基本的类概念、实例属性、方法及一些高级应用。
内容从浅入深。

例子 1：定义一个简单的类

class Dog:def __init__(self, name):self.name = namedef bark(self):return "Woof!"# 使用类
my_dog = Dog("Buddy")
print(my_dog.name)  # 输出: Buddy
print(my_dog.bark())  # 输出: Woof!

例子 2：类属性和实例属性

class Car:wheels = 4    # 类属性，所有实例共享def __init__(self, color):self.color = color  # 实例属性，每个实例独有# 使用类
my_car = Car("red")
print(my_car.wheels)  # 输出: 4
print(my_car.color)   # 输出: red

例子 3：私有属性和命名风格

class Account:def __init__(self, owner, amount):self.owner = ownerself.__amount = amount   # 私有属性def show_balance(self):return f"{self.owner} has ${self.__amount} in the account."# 使用类
account = Account("John", 500)
print(account.show_balance())  # John has $500 in the account.

例子 4：类方法和静态方法

class Circle:pi = 3.14  # 类属性def __init__(self, radius):self.radius = radius@classmethoddef from_diameter(cls, diameter):return cls(diameter / 2)@staticmethoddef is_valid_radius(radius):return radius > 0# 使用类
circle = Circle.from_diameter(10)
print(circle.radius)  # 输出: 5.0
print(Circle.is_valid_radius(5))  # 输出: True

例子 5：继承

class Animal:def speak(self):return "Some sound"class Cat(Animal):def speak(self):return "Meow"# 使用类
my_cat = Cat()
print(my_cat.speak())  # 输出: Meow

例子 6：多态和抽象类

from abc import ABC, abstractmethodclass Animal(ABC):@abstractmethoddef speak(self):passclass Dog(Animal):def speak(self):return "Woof!"class Cat(Animal):def speak(self):return "Meow"# 使用类
animals = [Dog(), Cat()]
for animal in animals:print(animal.speak())  # 输出: Woof! 和 Meow!

例子 7：属性装饰器

class Celsius:def __init__(self, temperature=0):self._temperature = temperature@propertydef temperature(self):return self._temperature@temperature.setterdef temperature(self, value):if value < -273.15:raise ValueError("Temperature below -273.15 is not possible")self._temperature = value# 使用类
weather = Celsius()
weather.temperature = 25
print(weather.temperature)  # 输出: 25
try:weather.temperature = -300
except ValueError as e:print(e)  # 输出: Temperature below -273.15 is not possible

例子 8：重载运算符

class Vector:def __init__(self, x, y):self.x = xself.y = ydef __add__(self, other):return Vector(self.x + other.x, self.y + other.y)def __str__(self):return f"Vector({self.x}, {self.y})"# 使用类
v1 = Vector(2, 4)
v2 = Vector(1, 3)
print(v1 + v2)  # 输出: Vector(3, 7)

例子 9：多重继承

class Engine:def start(self):return "Engine starting"class Camera:def click(self):return "Clicking photo"class Phone(Engine, Camera):def make_call(self):return "Making call"# 使用类
smartphone = Phone()
print(smartphone.start())  # 输出: Engine starting
print(smartphone.click())  # 输出: Clicking photo

例子 10：复合

class Engine:def start(self):return "Engine has been started"class Car:def __init__(self):self.engine = Engine()def start(self):return self.engine.start()# 使用类
my_car = Car()
print(my_car.start())  # 输出: Engine has been started