go语言 装饰器模式

package decorator

import (
   "fmt"
   "reflect"
)

func Decorator(decoPtr, fn interface{}) (err error) {
   var decoratedFunc, targetFunc reflect.Value

 decoratedFunc = reflect.ValueOf(decoPtr).Elem()
   targetFunc = reflect.ValueOf(fn)

   v := reflect.MakeFunc(targetFunc.Type(),
 func(in []reflect.Value) (out []reflect.Value) {
         fmt.Println("before")
         out = targetFunc.Call(in)
         fmt.Println("after")
         return
 })

   decoratedFunc.Set(v)
   return
}

package decorator

import (
   "fmt"
   "testing"
)

func foo(a, b, c int) int {
   fmt.Printf("%d, %d, %d 
", a, b, c)
   return a + b + c
}

func bar(a, b string) string {
   fmt.Printf("%s, %s 
", a, b)
   return a + b
}

func TestDecorator(t *testing.T) {
   //type MyFoo func(int, int, int) int
   //var myfoo MyFoo
   //Decorator(&myfoo, foo)
   //myfoo(1, 2, 3)
 mybar := bar
 Decorator(&mybar, bar)
   mybar("hello,", "world!")

}