Minimize struct copying

by using pointer func receivers and slices of struct pointers where possible.

app.go

@@ -27,7 +27,7 @@ type App struct {
 	// Version of the program
 	Version string
 	// List of commands to execute
-	Commands []Command
+	Commands []*Command
 	// List of flags to parse
 	Flags []Flag
 	// Boolean to enable bash completion commands
@@ -37,7 +37,7 @@ type App struct {
 	// Boolean to hide built-in version flag and the VERSION section of help
 	HideVersion bool
 	// Populate on app startup, only gettable through method Categories()
-	categories CommandCategories
+	categories *CommandCategories
 	// An action to execute when the bash-completion flag is set
 	BashComplete BashCompleteFunc
 	// An action to execute before any subcommands are run, but after the context is ready
@@ -55,7 +55,7 @@ type App struct {
 	// Compilation date
 	Compiled time.Time
 	// List of all authors who contributed
-	Authors []Author
+	Authors []*Author
 	// Copyright of the binary if any
 	Copyright string
 	// Writer writer to write output to
@@ -104,7 +104,7 @@ func (a *App) Setup() {
 
 	a.didSetup = true
 
-	newCmds := []Command{}
+	newCmds := []*Command{}
 	for _, c := range a.Commands {
 		if c.HelpName == "" {
 			c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
@@ -113,7 +113,7 @@ func (a *App) Setup() {
 	}
 	a.Commands = newCmds
 
-	a.categories = CommandCategories{}
+	a.categories = NewCommandCategories()
 	for _, command := range a.Commands {
 		a.categories = a.categories.AddCommand(command.Category, command)
 	}
@@ -121,8 +121,9 @@ func (a *App) Setup() {
 
 	// append help to commands
 	if a.Command(helpCommand.Name) == nil && !a.HideHelp {
-		a.Commands = append(a.Commands, helpCommand)
-		if !reflect.DeepEqual(HelpFlag, BoolFlag{}) {
+		a.appendCommand(helpCommand)
+
+		if HelpFlag != nil {
 			a.appendFlag(HelpFlag)
 		}
 	}
@@ -224,14 +225,15 @@ func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 	// append help to commands
 	if len(a.Commands) > 0 {
 		if a.Command(helpCommand.Name) == nil && !a.HideHelp {
-			a.Commands = append(a.Commands, helpCommand)
-			if !reflect.DeepEqual(HelpFlag, BoolFlag{}) {
+			a.appendCommand(helpCommand)
+
+			if HelpFlag != nil {
 				a.appendFlag(HelpFlag)
 			}
 		}
 	}
 
-	newCmds := []Command{}
+	newCmds := []*Command{}
 	for _, c := range a.Commands {
 		if c.HelpName == "" {
 			c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
@@ -331,7 +333,7 @@ func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 func (a *App) Command(name string) *Command {
 	for _, c := range a.Commands {
 		if c.HasName(name) {
-			return &c
+			return c
 		}
 	}
 
@@ -339,7 +341,7 @@ func (a *App) Command(name string) *Command {
 }
 
 // Categories returns a slice containing all the categories with the commands they contain
-func (a *App) Categories() CommandCategories {
+func (a *App) Categories() *CommandCategories {
 	return a.categories
 }
 
@@ -347,7 +349,7 @@ func (a *App) Categories() CommandCategories {
 // Hidden=false
 func (a *App) VisibleCategories() []*CommandCategory {
 	ret := []*CommandCategory{}
-	for _, category := range a.categories {
+	for _, category := range a.categories.Categories {
 		if visible := func() *CommandCategory {
 			for _, command := range category.Commands {
 				if !command.Hidden {
@@ -363,8 +365,8 @@ func (a *App) VisibleCategories() []*CommandCategory {
 }
 
 // VisibleCommands returns a slice of the Commands with Hidden=false
-func (a *App) VisibleCommands() []Command {
-	ret := []Command{}
+func (a *App) VisibleCommands() []*Command {
+	ret := []*Command{}
 	for _, command := range a.Commands {
 		if !command.Hidden {
 			ret = append(ret, command)
@@ -398,9 +400,15 @@ func (a *App) errWriter() io.Writer {
 	return a.ErrWriter
 }
 
-func (a *App) appendFlag(flag Flag) {
-	if !a.hasFlag(flag) {
-		a.Flags = append(a.Flags, flag)
+func (a *App) appendFlag(fl Flag) {
+	if !hasFlag(a.Flags, fl) {
+		a.Flags = append(a.Flags, fl)
+	}
+}
+
+func (a *App) appendCommand(c *Command) {
+	if !hasCommand(a.Commands, c) {
+		a.Commands = append(a.Commands, c)
 	}
 }
 
@@ -411,7 +419,7 @@ type Author struct {
 }
 
 // String makes Author comply to the Stringer interface, to allow an easy print in the templating process
-func (a Author) String() string {
+func (a *Author) String() string {
 	e := ""
 	if a.Email != "" {
 		e = "<" + a.Email + "> "