flags.go

package main

import (
    "flag"
    "fmt"
    "strconv"
    "time"
)

type intervalFlag struct {
    set   bool
    value time.Duration
}

// Set is called by the flag package when the flag is set.
func (f *intervalFlag) Set(s string) error {
    f.set = true
    var seconds int
    var err error
    seconds, err = strconv.Atoi(s)
    if err != nil {
        return fmt.Errorf("invalid format for interval: %v", err)
    }
    f.value = time.Duration(seconds) * time.Second
    return nil
}

// String returns the string representation of the flag.
func (f *intervalFlag) String() string {
    if !f.set {
        return "not set"
    }
    return fmt.Sprintf("%d", f.value)
}

func DefineFlags() (intervalFlag, *bool, *bool) {
    var interval intervalFlag
    var helpFlag = flag.Bool("h", false, "Display help information (shorthand)")
    var versionFlag = flag.Bool("v", false, "Display the version of the application (shorthand)")

    flag.Var(&interval, "i", "Set interval for refreshing the display in seconds (shorthand)")
    flag.Var(&interval, "interval", "Set interval for refreshing the display in seconds")

    return interval, helpFlag, versionFlag
}