如何在Go语言中实现类似Ruby的send动态方法调用

package main

import "fmt"

// 定义一个全局或局部函数映射
var commandHandlers = map[string]func(){
    "sayHello": func() { fmt.Println("Hello, Go!") },
    "sayBye":   func() { fmt.Println("Goodbye, Go!") },
    "showTime": func() { fmt.Println("The current time will be displayed here.") },
}

func main() {
    // 模拟从外部获取命令字符串
    cmd := "sayHello"

    // 检查命令是否存在并执行
    if handler, ok := commandHandlers[cmd]; ok {
        handler() // 执行对应的函数
    } else {
        fmt.Printf("Error: Command '%s' not found.\n", cmd)
    }

    cmd = "sayBye"
    if handler, ok := commandHandlers[cmd]; ok {
        handler()
    }

    cmd = "unknownCommand"
    if handler, ok := commandHandlers[cmd]; ok {
        handler()
    } else {
        fmt.Printf("Error: Command '%s' not found.\n", cmd)
    }
}

package main

import (
    "fmt"
    "reflect"
)

// 定义一个示例结构体
type Greeter struct {
    Name string
}

// 定义结构体上的方法
func (g Greeter) SayHello() {
    fmt.Printf("Hello from %s!\n", g.Name)
}

func (g Greeter) Greet(message string) {
    fmt.Printf("%s says: %s\n", g.Name, message)
}

func (g Greeter) GetName() string {
    return g.Name
}

func main() {
    myGreeter := Greeter{Name: "GoReflect"}

    // 1. 动态调用无参数方法
    methodName := "SayHello"
    greeterValue := reflect.ValueOf(myGreeter)
    method := greeterValue.MethodByName(methodName)

    if method.IsValid() {
        method.Call(nil) // 调用无参数方法，传入nil
    } else {
        fmt.Printf("Error: Method '%s' not found on Greeter.\n", methodName)
    }

    // 2. 动态调用带参数方法
    methodName = "Greet"
    method = greeterValue.MethodByName(methodName)
    if method.IsValid() {
        // 准备参数
        args := []reflect.Value{reflect.ValueOf("Nice to meet you!")}
        method.Call(args)
    } else {
        fmt.Printf("Error: Method '%s' not found on Greeter.\n", methodName)
    }

    // 3. 动态调用带返回值方法
    methodName = "GetName"
    method = greeterValue.MethodByName(methodName)
    if method.IsValid() {
        results := method.Call(nil) // 调用无参数方法，获取返回值
        if len(results) > 0 {
            fmt.Printf("Method '%s' returned: %v\n", methodName, results[0].Interface())
        }
    } else {
        fmt.Printf("Error: Method '%s' not found on Greeter.\n", methodName)
    }

    // 尝试调用不存在的方法
    methodName = "NonExistentMethod"
    method = greeterValue.MethodByName(methodName)
    if !method.IsValid() {
        fmt.Printf("Successfully handled non-existent method '%s'.\n", methodName)
    }
}