Refactor help command implementation to hold actual Command

Readme.md

@@ -37,7 +37,7 @@ Read this in other languages: English | [简体中文](./Readme_zh-CN.md)
     - [.usage](#usage)
     - [.description and .summary](#description-and-summary)
     - [.helpOption(flags, description)](#helpoptionflags-description)
-    - [.addHelpCommand()](#addhelpcommand)
+    - [.helpCommand()](#helpcommand)
     - [More configuration](#more-configuration-2)
   - [Custom event listeners](#custom-event-listeners)
   - [Bits and pieces](#bits-and-pieces)
@@ -904,16 +904,18 @@ program
   .helpOption('-e, --HELP', 'read more information');
 ```
 
-### .addHelpCommand()
+### .helpCommand()
 
-A help command is added by default if your command has subcommands. You can explicitly turn on or off the implicit help command with `.addHelpCommand()` and `.addHelpCommand(false)`.
+A help command is added by default if your command has subcommands. You can explicitly turn on or off the implicit help command with `.helpCommand(true)` and `.helpCommand(false)`.
 
 You can both turn on and customise the help command by supplying the name and description:
 
 ```js
-program.addHelpCommand('assist [command]', 'show assistance');
+program.helpCommand('assist [command]', 'show assistance');
 ```
 
+(Or use `.addHelpCommand()` to add a command you construct yourself.)
+
 ### More configuration
 
 The built-in help is formatted using the Help class.

docs/deprecated.md

@@ -15,6 +15,7 @@ They are currently still available for backwards compatibility, but should not b
     - [Short option flag longer than a single character](#short-option-flag-longer-than-a-single-character)
     - [Import from `commander/esm.mjs`](#import-from-commanderesmmjs)
     - [cmd.\_args](#cmd_args)
+    - [.addHelpCommand(string|boolean|undefined)](#addhelpcommandstringbooleanundefined)
   - [Removed](#removed)
     - [Default import of global Command object](#default-import-of-global-command-object)
 
@@ -205,6 +206,27 @@ const registeredArguments = program.registeredArguments;
 
 Deprecated from Commander v11.
 
+### .addHelpCommand(string|boolean|undefined)
+
+This was originally used with a variety of parameters, but not by passing a Command object despite the "add" name.
+
+```js
+program.addHelpCommand('assist  [command]');
+program.addHelpCommand('assist', 'show assistance');
+program.addHelpCommand(false);
+
+```
+
+In new code you configure the help command with `.helpCommand()`. Or use `.addHelpCommand()` which now takes a Command object, like `.addCommand()`.
+
+```js
+program.helpCommand('assist [command]');
+program.helpCommand('assist', 'show assistance');
+program.helpCommand(false);
+
+program.addHelpCommand(new Command('assist').argument('[command]').description('show assistance'));
+
+```
 ## Removed
 
 ### Default import of global Command object

lib/command.js

@@ -71,10 +71,9 @@ class Command extends EventEmitter {
     this._helpDescription = 'display help for command';
     this._helpShortFlag = '-h';
     this._helpLongFlag = '--help';
-    this._addImplicitHelpCommand = undefined; // Deliberately undefined, not decided whether true or false
-    this._helpCommandName = 'help';
-    this._helpCommandnameAndArgs = 'help [command]';
-    this._helpCommandDescription = 'display help for command';
+    this._addImplicitHelpCommand = undefined; // undecided whether true or false yet, not inherited
+    /** @type {Command} */
+    this._helpCommand = undefined; // lazy initialised, inherited
     this._helpConfiguration = {};
   }
 
@@ -93,9 +92,7 @@ class Command extends EventEmitter {
     this._helpDescription = sourceCommand._helpDescription;
     this._helpShortFlag = sourceCommand._helpShortFlag;
     this._helpLongFlag = sourceCommand._helpLongFlag;
-    this._helpCommandName = sourceCommand._helpCommandName;
-    this._helpCommandnameAndArgs = sourceCommand._helpCommandnameAndArgs;
-    this._helpCommandDescription = sourceCommand._helpCommandDescription;
+    this._helpCommand = sourceCommand._helpCommand;
     this._helpConfiguration = sourceCommand._helpConfiguration;
     this._exitCallback = sourceCommand._exitCallback;
     this._storeOptionsAsProperties = sourceCommand._storeOptionsAsProperties;
@@ -369,39 +366,76 @@ class Command extends EventEmitter {
   }
 
   /**
-   * Override default decision whether to add implicit help command.
+   * Customise or override default help command. By default a help command is automatically added if your command has subcommands.
    *
-   *    addHelpCommand() // force on
-   *    addHelpCommand(false); // force off
-   *    addHelpCommand('help [cmd]', 'display help for [cmd]'); // force on with custom details
+   *    program.helpCommand('help [cmd]');
+   *    program.helpCommand('help [cmd]', 'show help');
+   *    program.helpCommand(false); // suppress default help command
+   *    program.helpCommand(true); // add help command even if no subcommands
    *
+   * @param {string|boolean} enableOrNameAndArgs - enable with custom name and/or arguments, or boolean to override whether added
+   * @param {string} [description] - custom description
    * @return {Command} `this` command for chaining
    */
 
-  addHelpCommand(enableOrNameAndArgs, description) {
-    if (enableOrNameAndArgs === false) {
-      this._addImplicitHelpCommand = false;
-    } else {
-      this._addImplicitHelpCommand = true;
-      if (typeof enableOrNameAndArgs === 'string') {
-        this._helpCommandName = enableOrNameAndArgs.split(' ')[0];
-        this._helpCommandnameAndArgs = enableOrNameAndArgs;
-      }
-      this._helpCommandDescription = description || this._helpCommandDescription;
+  helpCommand(enableOrNameAndArgs, description) {
+    if (typeof enableOrNameAndArgs === 'boolean') {
+      this._addImplicitHelpCommand = enableOrNameAndArgs;
+      return this;
     }
+
+    enableOrNameAndArgs = enableOrNameAndArgs ?? 'help [command]';
+    const [, helpName, helpArgs] = enableOrNameAndArgs.match(/([^ ]+) *(.*)/);
+    const helpDescription = description ?? 'display help for command';
+
+    const helpCommand = this.createCommand(helpName);
+    helpCommand.helpOption(false);
+    if (helpArgs) helpCommand.arguments(helpArgs);
+    if (helpDescription) helpCommand.description(helpDescription);
+
+    this._addImplicitHelpCommand = true;
+    this._helpCommand = helpCommand;
+
     return this;
   }
 
   /**
-   * @return {boolean}
-   * @package internal use only
+   * Add prepared custom help command.
+   *
+   * @param {(Command|string|boolean)} helpCommand - custom help command, or deprecated enableOrNameAndArgs as for `.helpCommand()`
+   * @param {string} [deprecatedDescription] - deprecated custom description used with custom name only
+   * @return {Command} `this` command for chaining
    */
+  addHelpCommand(helpCommand, deprecatedDescription) {
+    // If not passed an object, call through to helpCommand for backwards compatibility,
+    // as addHelpCommand was originally used like helpCommand is now.
+    if (typeof helpCommand !== 'object') {
+      this.helpCommand(helpCommand, deprecatedDescription);
+      return this;
+    }
+
+    this._addImplicitHelpCommand = true;
+    this._helpCommand = helpCommand;
+    return this;
+  }
 
-  _hasImplicitHelpCommand() {
-    if (this._addImplicitHelpCommand === undefined) {
-      return this.commands.length && !this._actionHandler && !this._findCommand('help');
+  /**
+   * Lazy create help command.
+   *
+   * @return {(Command|null)}
+   * @package
+   */
+  _getHelpCommand() {
+    const hasImplicitHelpCommand = this._addImplicitHelpCommand ??
+      (this.commands.length && !this._actionHandler && !this._findCommand('help'));
+
+    if (hasImplicitHelpCommand) {
+      if (this._helpCommand === undefined) {
+        this.helpCommand(undefined, undefined); // use default name and description
+      }
+      return this._helpCommand;
     }
-    return this._addImplicitHelpCommand;
+    return null;
   }
 
   /**
@@ -1315,7 +1349,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
     if (operands && this._findCommand(operands[0])) {
       return this._dispatchSubcommand(operands[0], operands.slice(1), unknown);
     }
-    if (this._hasImplicitHelpCommand() && operands[0] === this._helpCommandName) {
+    if (this._getHelpCommand() && operands[0] === this._getHelpCommand().name()) {
       return this._dispatchHelpCommand(operands[1]);
     }
     if (this._defaultCommandName) {
@@ -1572,7 +1606,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
           operands.push(arg);
           if (args.length > 0) unknown.push(...args);
           break;
-        } else if (arg === this._helpCommandName && this._hasImplicitHelpCommand()) {
+        } else if (this._getHelpCommand() && arg === this._getHelpCommand().name()) {
           operands.push(arg);
           if (args.length > 0) operands.push(...args);
           break;

lib/help.js

@@ -26,13 +26,8 @@ class Help {
 
   visibleCommands(cmd) {
     const visibleCommands = cmd.commands.filter(cmd => !cmd._hidden);
-    if (cmd._hasImplicitHelpCommand()) {
-      // Create a command matching the implicit help command.
-      const [, helpName, helpArgs] = cmd._helpCommandnameAndArgs.match(/([^ ]+) *(.*)/);
-      const helpCommand = cmd.createCommand(helpName)
-        .helpOption(false);
-      helpCommand.description(cmd._helpCommandDescription);
-      if (helpArgs) helpCommand.arguments(helpArgs);
+    const helpCommand = cmd._getHelpCommand();
+    if (helpCommand && !helpCommand._hidden) {
       visibleCommands.push(helpCommand);
     }
     if (this.sortSubcommands) {