feat: set default values for options and arguments

generate.go

@@ -183,6 +183,9 @@ func (g *generator) genCmdUsageFunc(c *command) error {
 			case "roomy":
 				content := "   " + o.usgNameAndArg() + "\n"
 				content += "      " + wrapBlurb(o.data.Blurb, 6, g.usgTextWidth)
+				if v, ok := o.data.getConfig("default"); ok {
+					content += "\n\n      [default: " + v + "]"
+				}
 				if v, ok := o.data.getConfig("env"); ok {
 					content += "\n\n      [env: " + v + "]"
 				}
@@ -193,6 +196,9 @@ func (g *generator) genCmdUsageFunc(c *command) error {
 			default:
 				paddedNameAndArg := fmt.Sprintf("   %-*s   ", optNameColWidth, o.usgNameAndArg())
 				desc := o.data.Blurb
+				if v, ok := o.data.getConfig("default"); ok {
+					desc += " (default: " + v + ")"
+				}
 				if v, ok := o.data.getConfig("env"); ok {
 					desc += " [$" + v + "]"
 				}
@@ -214,6 +220,9 @@ func (g *generator) genCmdUsageFunc(c *command) error {
 			case "roomy":
 				content := "   " + a.UsgName() + "\n"
 				content += "      " + wrapBlurb(a.data.Blurb, 6, g.usgTextWidth)
+				if v, ok := a.data.getConfig("default"); ok {
+					content += "\n\n      [default: " + v + "]"
+				}
 				if v, ok := a.data.getConfig("env"); ok {
 					content += "\n\n      [env: " + v + "]"
 				}
@@ -224,6 +233,9 @@ func (g *generator) genCmdUsageFunc(c *command) error {
 			default:
 				paddedName := fmt.Sprintf("   %-*s   ", argNameColWidth, a.UsgName())
 				desc := a.data.Blurb
+				if v, ok := a.data.getConfig("default"); ok {
+					desc += " (default: " + v + ")"
+				}
 				if v, ok := a.data.getConfig("env"); ok {
 					desc += " [$" + v + "]"
 				}
@@ -276,6 +288,21 @@ func (g *generator) genCmdParseFunc(c *command) error {
 	return nil
 }
 
+func (c *command) Defaults() string {
+	var s string
+	for _, o := range c.Opts {
+		if defVal, ok := o.data.getConfig("default"); ok {
+			s += fmt.Sprintf("\tc.%s = %s\n", o.FieldName, defVal)
+		}
+	}
+	for _, a := range c.Args {
+		if defVal, ok := a.data.getConfig("default"); ok {
+			s += fmt.Sprintf("\tc.%s = %s\n", a.FieldName, defVal)
+		}
+	}
+	return s
+}
+
 func (c *command) Parents() string {
 	s := ""
 	for i := range c.parentNames {

tmpls/parsefunc.go.tmpl

@@ -1,5 +1,7 @@
 
 func (c *{{ .TypeName }}) Parse(args []string) {
+	{{- with .Defaults }}
+{{ . }}{{ end }}
 	p := clapCommand{
 		usage: c.UsageHelp,