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

go/visitor/main.go

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+package main
+
+import "fmt"
+
+/*
+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。
+*/
+
+// 抽象Node接口 Shape
+type Shape interface {
+	Accept(visitor Visitor)
+	ClaimShape()
+}
+
+type Circle struct{}
+
+func (c *Circle) Accept(visitor Visitor) {
+	visitor.VisitCircle(c)
+}
+
+func (c *Circle) ClaimShape() {
+	fmt.Println("I am a Circle")
+}
+
+type Square struct{}
+
+func (s *Square) Accept(visitor Visitor) {
+	visitor.VisitSquare(s)
+}
+
+func (s *Square) ClaimShape() {
+	fmt.Println("I am a Square")
+}
+
+type Triangle struct{}
+
+func (t *Triangle) Accept(visitor Visitor) {
+	visitor.VisitTriangle(t)
+}
+
+func (t *Triangle) ClaimShape() {
+	fmt.Println("I am a Triangle")
+}
+
+// 抽象NodeVisitor接口 Visitor
+type Visitor interface {
+	VisitCircle(c *Circle)
+	VisitSquare(s *Square)
+	VisitTriangle(t *Triangle)
+}
+
+type ShapeVisitor struct{}
+
+func (sv *ShapeVisitor) VisitCircle(c *Circle) {
+	fmt.Print("Visiting Circle: ")
+	c.ClaimShape()
+}
+
+func (sv *ShapeVisitor) VisitSquare(s *Square) {
+	fmt.Print("Visiting Square: ")
+	s.ClaimShape()
+}
+
+func (sv *ShapeVisitor) VisitTriangle(t *Triangle) {
+	fmt.Print("Visiting Triangle: ")
+	t.ClaimShape()
+}
+
+func main() {
+	fmt.Println("========== 访问者模式 ==========")
+	shapes := []Shape{&Circle{}, &Square{}, &Triangle{}}
+	visitor := &ShapeVisitor{}
+
+	for _, shape := range shapes {
+		shape.Accept(visitor)
+	}
+	fmt.Println()
+	fmt.Println("======== 访问者模式结束 ========")
+}

python/visitor/main.py

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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 ========")

ts/src/visitor/index.ts

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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。
+*/
+
+// 抽象Node接口 Shape
+interface Shape {
+  accept(visitor: Visitor): void;
+  claimShape(): string;
+}
+
+class Circle implements Shape {
+  accept(visitor: Visitor): void {
+    visitor.visitCircle(this);
+  }
+  claimShape(): string {
+    return "I am a Circle";
+  }
+}
+
+class Square implements Shape {
+  accept(visitor: Visitor): void {
+    visitor.visitSquare(this);
+  }
+  claimShape(): string {
+    return "I am a Square";
+  }
+}
+
+class Triangle implements Shape {
+  accept(visitor: Visitor): void {
+    visitor.visitTriangle(this);
+  }
+  claimShape(): string {
+    return "I am a Triangle";
+  }
+}
+
+// 抽象Visitor接口
+interface Visitor {
+  visitCircle(circle: Circle): void;
+  visitSquare(square: Square): void;
+  visitTriangle(triangle: Triangle): void;
+}
+
+class ShapeVisitor implements Visitor {
+  visitCircle(circle: Circle): void {
+    console.log("Visiting Circle: ", circle.claimShape());
+  }
+  visitSquare(square: Square): void {
+    console.log("Visiting Square: ", square.claimShape());
+  }
+  visitTriangle(triangle: Triangle): void {
+    console.log("Visiting Triangle: ", triangle.claimShape());
+  }
+}
+
+(function () {
+  console.log("========== 访问者模式 ==========");
+  const shapes: Shape[] = [new Circle(), new Square(), new Triangle()];
+  const visitor: Visitor = new ShapeVisitor();
+
+  shapes.forEach((shape) => {
+    shape.accept(visitor);
+  });
+  console.log("\n======== 访问者模式结束 ========");
+})();