Golang custom flag usage

golang-custom-flag-usage.go

package main
import (
    "flag"
    "fmt"
)
func main() {
    flag.String("a", "", "flag 1")
    flag.String("b", "", "flag 2")
    flag.String("c", "", "flag 3")

    flag.Usage = func() {
        flagSet := flag.CommandLine
        fmt.Printf("Usage of %s:\n", "./tool")
        order := []string{"a", "b", "c"}
        for _, name := range order {
            flag := flagSet.Lookup(name)
            fmt.Printf("-%s\t%s\n", flag.Name,flag.Usage)
        }
    }
    flag.Parse()
}

/* 
[ output ]
Usage of ./tool:
-a	flag 1
-b	flag 2
-c	flag 3
*/

works like a charm, thanks!