class Dog:
    species = "Canis lupus"  # 类属性
def __init__(self, name):
    self.name = name  # 实例属性
创建实例
dog1 = Dog("Buddy")
dog2 = Dog("Max")
访问类属性
print(Dog.species)       # 输出: Canis lupus
print(dog1.species)      # 输出: Canis lupus
print(dog2.species)      # 输出: Canis lupus

Dog.species = "Canis familiaris"
print(dog1.species)  # 输出: Canis familiaris
print(dog2.species)  # 输出: Canis familiaris

dog1.species = "Custom species"
print(dog1.species)  # 输出: Custom species（实例属性）
print(dog2.species)  # 输出: Canis familiaris（仍为类属性）
print(Dog.species)   # 输出: Canis familiaris

class Counter:
    count = 0  # 类属性，记录实例数量
def __init__(self):
    Counter.count += 1
c1 = Counter()
c2 = Counter()
print(Counter.count)  # 输出: 2

class BadExample:
    members = []  # 错误示范：可变类属性
def add_member(self, name):
    self.members.append(name)
g1 = BadExample()
g2 = BadExample()
g1.add_member("Alice")
g2.add_member("Bob")
print(g1.members)  # 输出: ['Alice', 'Bob'] —— 被共享了！