实现观察者模式示例，添加观察者、目标及具体实现，增强代码可读性

2026-01-06 23:44:08 +08:00
parent 5022b481a4
commit 5ddda4ee95
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+"""
+实例：
+汤宝宝一时想不开，当了房产中介。
+一旦片区内有房东发布了新房源信息，他就会第一时间通知所有潜在租客。
+"""
+
+from abc import ABC, abstractmethod
+
+
+# 抽象观察者类
+class Observer(ABC):
+    @abstractmethod
+    def update(self):
+        pass
+
+
+# 抽象目标接口
+class Subject(ABC):
+    @abstractmethod
+    def attach(self, observer: Observer):
+        pass
+
+    @abstractmethod
+    def detach(self, observer: Observer):
+        pass
+
+    @abstractmethod
+    def notify(self):
+        pass
+
+
+# 具体目标类
+class HousingAgency(Subject):
+    def __init__(self):
+        self._observers = []
+
+    def attach(self, observer: Observer):
+        self._observers.append(observer)
+
+    def detach(self, observer: Observer):
+        self._observers.remove(observer)
+
+    def notify(self):
+        print("房产中介通知了所有租客。")
+        for observer in self._observers:
+            observer.update()
+
+
+# 具体观察者类
+class Tenant(Observer):
+    def __init__(self, name: str):
+        self.name = name
+
+    def update(self):
+        print(f"租客{self.name}收到房源更新通知！")
+
+
+if __name__ == "__main__":
+    print("============= 观察者模式 =============")
+
+    agency = HousingAgency()
+    tenant1 = Tenant("小明")
+    tenant2 = Tenant("小红")
+
+    print("小红和小明订阅了房产中介的房源信息。")
+    agency.attach(tenant1)
+    agency.attach(tenant2)
+
+    print("房源上新了！")
+    agency.notify()
+
+    print("-----")
+    print("小红不想再接收房源信息，退订了。")
+    agency.detach(tenant2)
+    print("又有新房源了！")
+    agency.notify()
+
+    print("\n=========== 观察者模式结束 ===========")