reflection

reflect.go

package main

import (
	"fmt"
	"reflect"
	"strings"
)

func main() {
	l := []string{"foo", "bar", "baz"}
	ll := Map(l, func(s string) string {
		return strings.ToUpper(s)
	}).([]string)
	fmt.Printf("%v\n", ll)

	il := []int{1, 2, 3}
	ill := Map(il, func(i int) int {
		return i * 2
	}).([]int)
	fmt.Printf("%v\n", ill)
}

func Map(l interface{}, f interface{}) interface{} {
	lValue := reflect.ValueOf(l)
	fValue := reflect.ValueOf(f)
	retType := reflect.TypeOf(f).Out(0)
	retSlice := reflect.MakeSlice(reflect.SliceOf(retType), lValue.Len(), lValue.Len())
	for i := 0; i < lValue.Len(); i++ {
		retValue := fValue.Call([]reflect.Value{lValue.Index(i)})
		retSlice.Index(i).Set(retValue[0])
	}
	return retSlice.Interface()
}