Basic working flag category support

app.go

@@ -145,6 +145,14 @@ func (a *App) Setup() {
 		if c.HelpName == "" {
 			c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
 		}
+
+		fc := FlagCategories{}
+		for _, flag := range c.Flags {
+			fc = fc.AddFlag(flag.GetCategory(), flag)
+		}
+
+		sort.Sort(fc)
+		c.FlagCategories = fc
 		newCmds = append(newCmds, c)
 	}
 	a.Commands = newCmds
@@ -166,7 +174,7 @@ func (a *App) Setup() {
 	}
 	sort.Sort(a.categories)
 
-if a.Metadata == nil {
+	if a.Metadata == nil {
 		a.Metadata = make(map[string]interface{})
 	}
 
@@ -194,11 +202,6 @@ func (a *App) Run(arguments []string) (err error) {
 		return err
 	}
 
-	a.flagCategories = FlagCategories{}
-	for _, flag := range a.Flags {
-		a.flagCategories = a.flagCategories.AddFlag(flag.GetCategory(), flag)
-	}
-
 	set.SetOutput(ioutil.Discard)
 	err = set.Parse(arguments[1:])
 	nerr := normalizeFlags(a.Flags, set)
@@ -445,7 +448,7 @@ func (a *App) VisibleCommands() []Command {
 }
 
 // Categories returns a slice containing all the categories with the commands they contain
-func (a *App) FlagCategories() FlagCategories {
+func (a *App) VisibleFlagCategories() FlagCategories {
 	return a.flagCategories
 }
 

command.go

@@ -45,6 +45,8 @@ type Command struct {
 	Subcommands Commands
 	// List of flags to parse
 	Flags []Flag
+	// List of all flag categories
+	FlagCategories FlagCategories
 	// Treat all flags as normal arguments if true
 	SkipFlagParsing bool
 	// Skip argument reordering which attempts to move flags before arguments,
@@ -377,6 +379,11 @@ func (c Command) startApp(ctx *Context) error {
 	return app.RunAsSubcommand(ctx)
 }
 
+// Categories returns a slice containing all the categories with the commands they contain
+func (c Command) VisibleFlagCategories() FlagCategories {
+	return c.FlagCategories
+}
+
 // VisibleFlags returns a slice of the Flags with Hidden=false
 func (c Command) VisibleFlags() []Flag {
 	return visibleFlags(c.Flags)

help.go

@@ -54,9 +54,10 @@ CATEGORY:
    {{.Category}}{{end}}{{if .Description}}
 
 DESCRIPTION:
-   {{.Description}}{{end}}{{if .VisibleFlags}}
+   {{.Description}}{{end}}
 
-OPTIONS:
+OPTIONS:{{range .VisibleFlagCategories}}
+  {{.Name}}
    {{range .VisibleFlags}}{{.}}
    {{end}}{{end}}
 `
@@ -250,7 +251,10 @@ func printHelpCustom(out io.Writer, templ string, data interface{}, customFunc m
 		// If the writer is closed, t.Execute will fail, and there's nothing
 		// we can do to recover.
 		if os.Getenv("CLI_TEMPLATE_ERROR_DEBUG") != "" {
-			fmt.Fprintf(ErrWriter, "CLI TEMPLATE ERROR: %#v\n", err)
+      // Generic error message
+			fmt.Fprintf(ErrWriter, "CLI TEMPLATE ERROR DEBUG: %#v\n", err)
+      // Helpful error message
+			fmt.Fprintf(ErrWriter, "CLI TEMPLATE ERROR DEBUG: %#v\n", err.Error())
 		}
 		return
 	}