six_001

wechat_项目工具包/项目其它工具/单例模式.py

@@ -0,0 +1,67 @@
+import threading
+from dataclasses import dataclass
+
+
+class ParameterizedSingletonMeta(type):
+    """
+    参数化单例元类
+    行为：
+    - 相同 (类, args, kwargs) → 同一实例
+    - 不同参数 → 不同实例
+    """
+
+    _instances: dict = {}
+    _lock = threading.RLock()
+
+    def __call__(cls, *args, **kwargs):
+        # 1. kwargs 排序，保证顺序无关
+        kwargs_key = tuple(sorted(kwargs.items()))
+
+        # 2. 构造不可变的 key
+        key = (cls, args, kwargs_key)
+
+        # 3. 防御：确保所有参数都可 hash
+        try:
+            hash(key)
+        except TypeError as e:
+            raise ValueError(
+                f"{cls.__name__} 的单例参数必须全部可 hash"
+                ) from e
+
+        with cls._lock:
+            if key not in cls._instances:
+                cls._instances[key] = super().__call__(*args, **kwargs)
+            else:
+                print(f"[HIT] 命中缓存实例: {key}")
+
+        return cls._instances[key]
+
+    @classmethod
+    def get_all_instances(cls):
+        """调试用：返回当前已创建的所有实例"""
+        return list(cls._instances.values())
+
+
+@dataclass
+class Demo(metaclass=ParameterizedSingletonMeta):
+    """
+    示例：参数化单例对象
+    """
+
+    name: str
+
+    def __post_init__(self):
+        print(f"正在初始化 Demo(name={self.name})")
+
+    def __str__(self):
+        return f"<Demo name={self.name} id={id(self)}>"
+
+
+if __name__ == "__main__":
+    print("=== 测试 1：相同参数 ===")
+    d1 = Demo(name="config_A")
+    d2 = Demo(name="config_A")
+    print(d1)
+    print(d2)
+    print("是否同一实例：", d1 is d2)
+    print(ParameterizedSingletonMeta.get_all_instances())