options.go

package main

import (
	"flag"
	"fmt"
)

var options struct {
	s string
	i int
	f float64
}

func main() {
	flag.Parse()
	fmt.Println(options)
}

func init() {
	flag.StringVar(&options.s, "string", "", "a string")
	flag.IntVar(&options.i, "int", 0, "an int")
	flag.Float64Var(&options.f, "float", 0, "a float")
}