Make command DisplayName() public

This allows using the display name in templates or other code that want
to use the same value.

command.go

@@ -1190,7 +1190,7 @@ func (c *Command) InitDefaultHelpFlag() {
 	c.mergePersistentFlags()
 	if c.Flags().Lookup("help") == nil {
 		usage := "help for "
-		name := c.displayName()
+		name := c.DisplayName()
 		if name == "" {
 			usage += "this command"
 		} else {
@@ -1216,7 +1216,7 @@ func (c *Command) InitDefaultVersionFlag() {
 		if c.Name() == "" {
 			usage += "this command"
 		} else {
-			usage += c.displayName()
+			usage += c.DisplayName()
 		}
 		if c.Flags().ShorthandLookup("v") == nil {
 			c.Flags().BoolP("version", "v", false, usage)
@@ -1240,7 +1240,7 @@ func (c *Command) InitDefaultHelpCmd() {
 			Use:   "help [command]",
 			Short: "Help about any command",
 			Long: `Help provides help for any command in the application.
-Simply type ` + c.displayName() + ` help [path to command] for full details.`,
+Simply type ` + c.DisplayName() + ` help [path to command] for full details.`,
 			ValidArgsFunction: func(c *Command, args []string, toComplete string) ([]string, ShellCompDirective) {
 				var completions []string
 				cmd, _, e := c.Root().Find(args)
@@ -1431,10 +1431,12 @@ func (c *Command) CommandPath() string {
 	if c.HasParent() {
 		return c.Parent().CommandPath() + " " + c.Name()
 	}
-	return c.displayName()
+	return c.DisplayName()
 }
 
-func (c *Command) displayName() string {
+// DisplayName returns the name to display in help text. Returns command Name()
+// If CommandDisplayNameAnnoation is not set
+func (c *Command) DisplayName() string {
 	if displayName, ok := c.Annotations[CommandDisplayNameAnnotation]; ok {
 		return displayName
 	}
@@ -1444,7 +1446,7 @@ func (c *Command) displayName() string {
 // UseLine puts out the full usage for a given command (including parents).
 func (c *Command) UseLine() string {
 	var useline string
-	use := strings.Replace(c.Use, c.Name(), c.displayName(), 1)
+	use := strings.Replace(c.Use, c.Name(), c.DisplayName(), 1)
 	if c.HasParent() {
 		useline = c.parent.CommandPath() + " " + use
 	} else {
@@ -1650,7 +1652,7 @@ func (c *Command) GlobalNormalizationFunc() func(f *flag.FlagSet, name string) f
 // to this command (local and persistent declared here and by all parents).
 func (c *Command) Flags() *flag.FlagSet {
 	if c.flags == nil {
-		c.flags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
+		c.flags = flag.NewFlagSet(c.DisplayName(), flag.ContinueOnError)
 		if c.flagErrorBuf == nil {
 			c.flagErrorBuf = new(bytes.Buffer)
 		}
@@ -1665,7 +1667,7 @@ func (c *Command) Flags() *flag.FlagSet {
 func (c *Command) LocalNonPersistentFlags() *flag.FlagSet {
 	persistentFlags := c.PersistentFlags()
 
-	out := flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
+	out := flag.NewFlagSet(c.DisplayName(), flag.ContinueOnError)
 	c.LocalFlags().VisitAll(func(f *flag.Flag) {
 		if persistentFlags.Lookup(f.Name) == nil {
 			out.AddFlag(f)
@@ -1680,7 +1682,7 @@ func (c *Command) LocalFlags() *flag.FlagSet {
 	c.mergePersistentFlags()
 
 	if c.lflags == nil {
-		c.lflags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
+		c.lflags = flag.NewFlagSet(c.DisplayName(), flag.ContinueOnError)
 		if c.flagErrorBuf == nil {
 			c.flagErrorBuf = new(bytes.Buffer)
 		}
@@ -1708,7 +1710,7 @@ func (c *Command) InheritedFlags() *flag.FlagSet {
 	c.mergePersistentFlags()
 
 	if c.iflags == nil {
-		c.iflags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
+		c.iflags = flag.NewFlagSet(c.DisplayName(), flag.ContinueOnError)
 		if c.flagErrorBuf == nil {
 			c.flagErrorBuf = new(bytes.Buffer)
 		}
@@ -1737,7 +1739,7 @@ func (c *Command) NonInheritedFlags() *flag.FlagSet {
 // PersistentFlags returns the persistent FlagSet specifically set in the current command.
 func (c *Command) PersistentFlags() *flag.FlagSet {
 	if c.pflags == nil {
-		c.pflags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
+		c.pflags = flag.NewFlagSet(c.DisplayName(), flag.ContinueOnError)
 		if c.flagErrorBuf == nil {
 			c.flagErrorBuf = new(bytes.Buffer)
 		}
@@ -1750,9 +1752,9 @@ func (c *Command) PersistentFlags() *flag.FlagSet {
 func (c *Command) ResetFlags() {
 	c.flagErrorBuf = new(bytes.Buffer)
 	c.flagErrorBuf.Reset()
-	c.flags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
+	c.flags = flag.NewFlagSet(c.DisplayName(), flag.ContinueOnError)
 	c.flags.SetOutput(c.flagErrorBuf)
-	c.pflags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
+	c.pflags = flag.NewFlagSet(c.DisplayName(), flag.ContinueOnError)
 	c.pflags.SetOutput(c.flagErrorBuf)
 
 	c.lflags = nil
@@ -1869,7 +1871,7 @@ func (c *Command) mergePersistentFlags() {
 // If c.parentsPflags == nil, it makes new.
 func (c *Command) updateParentsPflags() {
 	if c.parentsPflags == nil {
-		c.parentsPflags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
+		c.parentsPflags = flag.NewFlagSet(c.DisplayName(), flag.ContinueOnError)
 		c.parentsPflags.SetOutput(c.flagErrorBuf)
 		c.parentsPflags.SortFlags = false
 	}