实现访问者模式示例，添加形状、访问者及具体实现，增强代码可读性

2026-01-07 20:24:46 +08:00
parent e5be1b62c2
commit a319494128
3 changed files with 228 additions and 0 deletions
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+"""
+实例：
+汤宝宝坚信搭积木是人类的未来，因此开办了一家积木厂。
+"""
+
+from abc import ABC, abstractmethod
+
+
+# 抽象Node接口 Shape
+class Shape(ABC):
+    @abstractmethod
+    def accept(self, visitor: "Visitor"):
+        pass
+
+    @abstractmethod
+    def claim_shape(self):
+        pass
+
+
+class Circle(Shape):
+    def accept(self, visitor):
+        visitor.visit_circle(self)
+
+    def claim_shape(self):
+        print("I am a Circle")
+
+
+class Square(Shape):
+    def accept(self, visitor):
+        visitor.visit_square(self)
+
+    def claim_shape(self):
+        print("I am a Square")
+
+
+class Triangle(Shape):
+    def accept(self, visitor):
+        visitor.visit_triangle(self)
+
+    def claim_shape(self):
+        print("I am a Triangle")
+
+
+# 抽象Visitor接口
+class Visitor(ABC):
+    @abstractmethod
+    def visit_circle(self, circle: Circle):
+        pass
+
+    @abstractmethod
+    def visit_square(self, square: Square):
+        pass
+
+    @abstractmethod
+    def visit_triangle(self, triangle: Triangle):
+        pass
+
+
+# 具体Visitor实现
+class ShapeVisitor(Visitor):
+    def visit_circle(self, circle: Circle):
+        print("Visiting Circle:", end=" ")
+        circle.claim_shape()
+
+    def visit_square(self, square: Square):
+        print("Visiting Square:", end=" ")
+        square.claim_shape()
+
+    def visit_triangle(self, triangle: Triangle):
+        print("Visiting Triangle:", end=" ")
+        triangle.claim_shape()
+
+
+if __name__ == "__main__":
+    print("========== 访问者模式 ==========")
+    shapes = [Circle(), Square(), Triangle()]
+    visitor = ShapeVisitor()
+    for shape in shapes:
+        shape.accept(visitor)
+
+    print("\n======== 访问者模式结束 ========")