实现代理模式示例，添加火车站和代售点类，增强代码可读性

python/proxy/main.py

@@ -0,0 +1,59 @@
+"""
+实例：
+汤宝宝买火车票，可以去火车站买，也可以去代售点买，但是汤宝宝选择全都要。然而，火车站总共只剩两张票，这可苦了小明了。
+"""
+
+from abc import ABC, abstractmethod
+
+
+class Seller(ABC):
+    @abstractmethod
+    def sell(self, name: str) -> bool:
+        pass
+
+
+class TrainStation(Seller):
+    stock: int
+
+    def __init__(self, stock: int) -> None:
+        print(f"火车站库存{stock}张票")
+        self.stock = stock
+
+    def sell(self, name: str) -> bool:
+        print(f"{name}去火车站买票。")
+        if self.stock > 0:
+            self.stock -= 1
+            print(f"{name}在火车站买到一张火车票。")
+            return True
+        else:
+            print(f"火车站没票了，{name}没买到票。")
+            return False
+
+class TicketAgency(Seller):
+    name: str
+    station: TrainStation
+
+    def __init__(self, name: str, station: TrainStation) -> None:
+        self.name = name
+        self.station = station
+
+    def sell(self, name: str) -> bool:
+        print(f"{name}去{self.name}买票。")
+        result = self.station.sell(self.name)
+        if result:
+            print(f"{name}在{self.name}买到一张火车票。")
+        else:
+            print(f"{name}在{self.name}没买到票。")
+        return result
+
+if __name__ == "__main__":
+    print("============= 代理模式 =============")
+    station = TrainStation(stock=2)
+    agency = TicketAgency(name="代售点A", station=station)
+    station.sell("汤宝宝")
+    agency.sell("汤宝宝")
+    print("")
+    agency.sell("小明")
+    station.sell("小明")
+
+    print("\n=========== 代理模式结束 ===========")