Override built in option -v, --version of package arg

cmd/example/main.go

@@ -0,0 +1,104 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strings"
+
+	"github.com/trzsz/go-arg"
+)
+
+type sshArgs struct {
+	Ver         bool     `arg:"-V,--version" help:"show program's version number and exit"`
+	Destination string   `arg:"positional" help:"alias in ~/.ssh/config, or [user@]hostname[:port]"`
+	Command     string   `arg:"positional" help:"command to execute instead of a login shell"`
+	Argument    []string `arg:"positional" help:"command arguments separated by spaces"`
+	Debug       bool     `arg:"-v,--debug" help:"verbose mode for debugging, same as ssh's -vvv"`
+}
+
+func (sshArgs) Description() string {
+	return "Simple ssh client with trzsz ( trz / tsz ) support.\n"
+}
+
+func (sshArgs) Version() string {
+	return fmt.Sprintf("trzsz ssh %s", kTsshVersion)
+}
+
+type Parser struct {
+	*arg.Parser
+}
+
+func (p *Parser) WriteHelp(w io.Writer) {
+	var b bytes.Buffer
+	p.Parser.WriteHelp(&b)
+	s := strings.Replace(b.String(), " [-v]", "", 1)
+	s = strings.Replace(s, "  -v, --version          show program's version number and exit\n", "", 1)
+	fmt.Fprint(w, s)
+
+}
+
+func (p *Parser) WriteUsage(w io.Writer) {
+	var b bytes.Buffer
+	p.Parser.WriteUsage(&b)
+	s := strings.Replace(b.String(), " [-v]", "", 1)
+	fmt.Fprint(w, s)
+
+}
+
+func NewParser(config arg.Config, dests ...interface{}) (*Parser, error) {
+	p, err := arg.NewParser(config, dests...)
+	return &Parser{p}, err
+}
+
+const kTsshVersion = "0.1.19"
+
+func main() {
+
+	log.SetFlags(log.Lshortfile)
+	log.Println("Override built in option `-v, --version` of package `arg`")
+	var (
+		args sshArgs
+	)
+
+	// Like `parser := arg.MustParse(args)` but override built in option `-v, --version` of package `arg`
+	parser, err := NewParser(arg.Config{}, &args)
+	if err != nil {
+		fmt.Fprintln(os.Stdout, err)
+		os.Exit(-1)
+	}
+	a2s := make([]string, 0) // without built in option
+	deb := false
+	for _, arg := range os.Args[1:] {
+		switch arg {
+		case "-h", "-help", "--help":
+			parser.WriteHelp(os.Stderr)
+			os.Exit(0)
+		case "-version", "--version":
+			fmt.Fprintln(os.Stderr, args.Version())
+			os.Exit(0)
+		case "-v":
+			deb = true
+		default:
+			a2s = append(a2s, arg)
+		}
+	}
+	err = parser.Parse(a2s)
+	if err != nil {
+		parser.WriteUsage(os.Stdout)
+		fmt.Fprintln(os.Stdout, err)
+		os.Exit(0)
+	}
+	if args.Ver {
+		fmt.Fprintln(os.Stderr, args.Version())
+		os.Exit(0)
+	}
+	args.Debug = args.Debug || deb
+	log.Println("Debug", args.Debug)
+	log.Println("Ver", args.Ver)
+	log.Println("Destination", args.Destination)
+	log.Println("Command", args.Command)
+	log.Println("Argument", args.Argument)
+}