subcmd

Overview ¶

Package subcmd implements subcommand parsing mechanism for the command-line.

Users can define commands and group them together into a parent subcommand, etc. to from subcommand hierarchies of arbitrary depths.

Commands can define flags using `flag.FlagSet` objects from the Go standard library. Commands can also provide detailed documentation which is optional.

A few special top-level commands "help", "flags", and "commands" are added automatically for documentation. More detailed documentation is collected through the optional `interface{ CommandHelp() string }` method on the Command objects.

EXAMPLE 1 ¶

func listJobs(ctx context.Context, args []string) error {
	...
	return nil
}

var listCmd = subcmd.New("jobs", "Prints the job list.", subcmd.MainFunc(listJobs))

EXAMPLE 2 ¶

type runCmd struct {
	background  bool
	port        int
	ip          string
	secretsPath string
	dataDir     string
}

// Run implements the `main` method for "run" subcommand.
func (r *runCmd) Run(ctx context.Context, args []string) error {
	...
	if len(p.dataDir) == 0 {
		p.dataDir = filepath.Join(os.Getenv("HOME"), ".data")
	}
	...
	return nil
}

// Command implements the subcmd.Command interface.
func (r *runCmd) Command() (*flag.FlagSet, MainFunc) {
	fset := flag.NewFlagSet("run", flag.ContinueOnError)
	fset.BoolVar(&r.background, "background", false, "runs the daemon in background")
	fset.IntVar(&r.port, "port", 10000, "TCP port number for the daemon")
	fset.StringVar(&r.ip, "ip", "0.0.0.0", "TCP ip address for the daemon")
	fset.StringVar(&r.secretsPath, "secrets-file", "", "path to credentials file")
	fset.StringVar(&r.dataDir, "data-dir", "", "path to the data directory")
	return fset, MainFunc(r.Run)
}