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 ========")
+}