Add custom help function to command

pkg/cli/commands.go

@@ -4,18 +4,20 @@ package cli
 
 import (
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 )
 
 // Command structure contains program/command information (command name and description).
 type Command struct {
-	Name          string
-	Description   string
-	Configuration interface{}
-	Resources     []ResourceLoader
-	Run           func([]string) error
-	Hidden        bool
+	Name           string
+	Description    string
+	Configuration  interface{}
+	Resources      []ResourceLoader
+	Run            func([]string) error
+	CustomHelpFunc func(io.Writer, *Command) error
+	Hidden         bool
 	// AllowArg if not set, disallows any argument that is not a known command or a sub-command.
 	AllowArg    bool
 	subCommands []*Command
@@ -35,6 +37,15 @@ func (c *Command) AddCommand(cmd *Command) error {
 	return nil
 }
 
+// PrintHelp calls the custom help function of the command if it's set.
+// Otherwise, it calls the default help function.
+func (c *Command) PrintHelp(w io.Writer) error {
+	if c.CustomHelpFunc != nil {
+		return c.CustomHelpFunc(w, c)
+	}
+	return PrintHelp(w, c)
+}
+
 // Execute Executes a command.
 func Execute(cmd *Command) error {
 	return execute(cmd, os.Args, true)
@@ -92,16 +103,16 @@ func execute(cmd *Command, args []string, root bool) error {
 
 func run(cmd *Command, args []string) error {
 	if len(args) > 0 && !isFlag(args[0]) && !cmd.AllowArg {
-		_ = PrintHelp(os.Stdout, cmd)
+		_ = cmd.PrintHelp(os.Stdout)
 		return fmt.Errorf("command not found: %s", args[0])
 	}
 
 	if isHelp(args) {
-		return PrintHelp(os.Stdout, cmd)
+		return cmd.PrintHelp(os.Stdout)
 	}
 
 	if cmd.Run == nil {
-		_ = PrintHelp(os.Stdout, cmd)
+		_ = cmd.PrintHelp(os.Stdout)
 		return fmt.Errorf("command %s is not runnable", cmd.Name)
 	}