Init

.gitignore

@@ -0,0 +1 @@
+gh

help.go

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+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"text/template"
+)
+
+var cmdVersion = &Command{
+	Run:   runVersion,
+	Usage: "version",
+	Short: "show gh version",
+	Long:  `Version shows the gh client version showstring.`,
+}
+
+func runVersion(cmd *Command, args []string) {
+	fmt.Println(Version)
+}
+
+var cmdHelp = &Command{
+	Usage: "help [command]",
+	Short: "show help",
+	Long:  `Help shows usage for a command.`,
+}
+
+func init() {
+	cmdHelp.Run = runHelp // break init loop
+}
+
+func runHelp(cmd *Command, args []string) {
+	if len(args) == 0 {
+		printUsage()
+		return // not os.Exit(2); success
+	}
+	if len(args) != 1 {
+		log.Fatal("too many arguments")
+	}
+
+	for _, cmd := range commands {
+		if cmd.Name() == args[0] {
+			cmd.printUsage()
+			return
+		}
+	}
+
+	fmt.Fprintf(os.Stderr, "Unknown help topic: %q. Run 'acldt helpp'.\n", args[0])
+	os.Exit(2)
+}
+
+var usageTemplate = template.Must(template.New("usage").Parse(`Usage: gh [command] [options] [arguments]
+
+Supported commands are:
+{{range .Commands}}{{if .Runnable}}{{if .ShowUsage}}
+{{.Name | printf "%-8s"}} {{.Short}}{{end}}{{end}}{{end}}
+
+See 'gh help [command]' for more information about a command.
+`))
+
+func printUsage() {
+	usageTemplate.Execute(os.Stdout, struct {
+		Commands []*Command
+	}{
+		commands,
+	})
+}
+
+func usage() {
+	printUsage()
+	os.Exit(2)
+}

main.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type Command struct {
+	Run  func(cmd *Command, args []string)
+	Flag flag.FlagSet
+
+	Usage string
+	Short string
+	Long  string
+}
+
+func (c *Command) printUsage() {
+	if c.Runnable() {
+		fmt.Printf("Usage: gh %s\n\n", c.Usage)
+	}
+	fmt.Println(strings.Trim(c.Long, "\n"))
+}
+
+func (c *Command) Name() string {
+	name := c.Usage
+	i := strings.Index(name, " ")
+	if i >= 0 {
+		name = name[:i]
+	}
+	return name
+}
+
+func (c *Command) Runnable() bool {
+	return c.Run != nil
+}
+
+var commands = []*Command{}
+
+func main() {
+	args := os.Args[1:]
+	if len(args) < 1 {
+		usage()
+	}
+
+	for _, cmd := range commands {
+		if cmd.Name() == args[0] && cmd.Run != nil {
+			cmd.Flag.Usage = func() {
+				cmd.printUsage()
+			}
+			if err := cmd.Flag.Parse(args[1:]); err != nil {
+				os.Exit(2)
+			}
+			cmd.Run(cmd, cmd.Flag.Args())
+			return
+		}
+	}
+
+	fmt.Fprintf(os.Stderr, "Unknown command: %s\n", args[0])
+	usage()
+}

version.go

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+package main
+
+const Version = "dev"