饿汉式单例产生班长，模拟班会举行

class ClassPresident:
__instance = None # 类变量，用于存储唯一实例

def __init__(self, name):
self.name = name

@classmethod
def get_instance(cls, name):
if not cls.__instance:
cls.__instance = ClassPresident(name)
return cls.__instance

def call_meeting(self):
print(f"{self.name}主持班会，开始发言！")

def end_meeting(self):
print(f"{self.name}宣布本次班会结束。")

# 饿汉式单例模式
class_president = ClassPresident.get_instance("张三")
print(f"班长是{class_president.name}")
class_president.call_meeting()
class_president.end_meeting()

# 尝试创建另一个班长实例
class_president2 = ClassPresident.get_instance("李四")
print(f"班长是{class_president2.name}")
class_president2.call_meeting() # 与班长1相同
class_president2.end_meeting() # 与班长1相同