Example of a gnuflag var that supports both --name and --name=value

waitflag.go

package main

import (
        "fmt"
        "time"

        "github.com/juju/gnuflag"
)

type waitFlag struct {
        forever bool
        d       time.Duration
}

func (f *waitFlag) Set(s string) error {
        if s == "true" {
                f.forever = true
                return nil
        }
        v, err := time.ParseDuration(s)
        if err != nil {
                return err
        }
        f.d = v
        return nil
}

func (f *waitFlag) String() string {
        if f.forever {
                return "true"
        }
        if f.d == 0 {
                return ""
        }
        return f.d.String()
}

func (f *waitFlag) IsBoolFlag() bool {
        return true
}

func main() {
        var waitFlag waitFlag
        gnuflag.Var(&waitFlag, "wait", "")
        gnuflag.Parse(false)
        fmt.Println(waitFlag.forever, waitFlag.d)
}