class Dog:
    # 类变量
    species = "Canine"
    
    # 构造方法
    def __init__(self, name, age):
        self.name = name  # 实例变量
        self.age = age
    
    # 实例方法
    def bark(self):
        return f"{self.name} says Woof!"
    
    # 类方法
    @classmethod
    def from_birth_year(cls, name, birth_year):
        return cls(name, 2024 - birth_year)
    
    # 静态方法
    @staticmethod
    def is_mammal():
        return True
    
    def __str__(self):
        return f"Dog({self.name}, {self.age})"
    
    def __repr__(self):
        return f"Dog(name='{self.name}', age={self.age})"

dog = Dog("Rex", 5)
print(dog.bark())  # Rex says Woof!

class Animal:
    def __init__(self, name):
        self.name = name
    
    def speak(self):
        raise NotImplementedError

class Dog(Animal):
    def speak(self):
        return f"{self.name}: Woof!"

class Cat(Animal):
    def speak(self):
        return f"{self.name}: Meow!"

# 多态
animals = [Dog("Rex"), Cat("Kitty")]
for animal in animals:
    print(animal.speak())

# super()
class Puppy(Dog):
    def __init__(self, name, trick):
        super().__init__(name)
        self.trick = trick

# 方法解析顺序（MRO）
print(Puppy.__mro__)

class Vector:
    def __init__(self, x, y):
        self.x = x
        self.y = y
    
    def __add__(self, other):
        return Vector(self.x + other.x, self.y + other.y)
    
    def __mul__(self, scalar):
        return Vector(self.x * scalar, self.y * scalar)
    
    def __abs__(self):
        return (self.x**2 + self.y**2)**0.5
    
    def __eq__(self, other):
        return self.x == other.x and self.y == other.y
    
    def __repr__(self):
        return f"Vector({self.x}, {self.y})"

v1 = Vector(3, 4)
v2 = Vector(1, 2)
print(v1 + v2)    # Vector(4, 6)
print(v1 * 3)     # Vector(9, 12)
print(abs(v1))    # 5.0

class Temperature:
    def __init__(self, celsius=0):
        self._celsius = celsius
    
    @property
    def celsius(self):
        return self._celsius
    
    @celsius.setter
    def celsius(self, value):
        if value < -273.15:
            raise ValueError("Below absolute zero!")
        self._celsius = value
    
    @property
    def fahrenheit(self):
        return self._celsius * 9/5 + 32

temp = Temperature(25)
temp.celsius = 30  # 使用 setter
print(temp.fahrenheit)  # 86.0

from dataclasses import dataclass

@dataclass
class Point:
    x: float
    y: float
    z: float = 0.0
    
    def distance(self, other):
        return ((self.x - other.x)**2 + 
                (self.y - other.y)**2 + 
                (self.z - other.z)**2)**0.5

p1 = Point(1, 2, 3)
p2 = Point(4, 5, 6)
print(p1.distance(p2))  # 5.196...
print(p1)  # Point(x=1, y=2, z=3)