Factory routine to create a new unattached argument

esm.mjs

@@ -1,4 +1,15 @@
 import commander from './index.js';
 
 // wrapper to provide named exports for ESM.
-export const { program, Option, Command, Argument, CommanderError, InvalidOptionArgumentError, Help, createCommand, createOption } = commander;
+export const {
+  program,
+  createCommand,
+  createArgument,
+  createOption,
+  CommanderError,
+  InvalidOptionArgumentError,
+  Command,
+  Argument,
+  Option,
+  Help
+} = commander;

index.js

@@ -836,6 +836,21 @@ class Command extends EventEmitter {
     return this;
   };
 
+  /**
+   * Factory routine to create a new unattached argument.
+   *
+   * See .argument() for creating an attached argument, which uses this routine to
+   * create the argument. You can override createArgument to return a custom argument.
+   *
+   * @param {string} name
+   * @param {string} [description]
+   * @return {Argument} new argument
+   */
+
+  createArgument(name, description) {
+    return new Argument(name, description);
+  };
+
   /**
    * Define argument syntax for command.
    *
@@ -852,7 +867,7 @@ class Command extends EventEmitter {
    * @return {Command} `this` command for chaining
    */
   argument(name, description) {
-    const argument = new Argument(name, description);
+    const argument = this.createArgument(name, description);
     this.addArgument(argument);
     return this;
   }

tests/command.createArgument.test.js

@@ -0,0 +1,40 @@
+const commander = require('../');
+
+class MyArgument extends commander.Argument {
+  constructor(name, description) {
+    super(name, description);
+    this.myProperty = 'MyArgument';
+  };
+}
+
+class MyCommand extends commander.Command {
+  createArgument(name, description) {
+    return new MyArgument(name, description);
+  };
+
+  // createCommand for testing .command('sub <file>')
+  createCommand(name) {
+    return new MyCommand(name);
+  }
+}
+
+test('when override createArgument then used for argument()', () => {
+  const program = new MyCommand();
+  program.argument('<file>');
+  expect(program._args.length).toEqual(1);
+  expect(program._args[0].myProperty).toEqual('MyArgument');
+});
+
+test('when override createArgument then used for arguments()', () => {
+  const program = new MyCommand();
+  program.arguments('<file>');
+  expect(program._args.length).toEqual(1);
+  expect(program._args[0].myProperty).toEqual('MyArgument');
+});
+
+test('when override createArgument and createCommand then used for argument of command()', () => {
+  const program = new MyCommand();
+  const sub = program.command('sub <file>');
+  expect(sub._args.length).toEqual(1);
+  expect(sub._args[0].myProperty).toEqual('MyArgument');
+});

tests/esm-imports-test.mjs

@@ -1,4 +1,4 @@
-import { program, Command, Option, Argument, CommanderError, InvalidOptionArgumentError, Help, createCommand, createOption } from '../esm.mjs';
+import { program, Command, Option, Argument, CommanderError, InvalidOptionArgumentError, Help, createCommand, createArgument, createOption } from '../esm.mjs';
 
 // Do some simple checks that expected imports are available at runtime.
 // Run using `npm run test-esm`.
@@ -30,6 +30,8 @@ checkClass(new Argument('<file>'), 'Argument');
 
 console.log('Checking createCommand');
 check(typeof createCommand === 'function', 'createCommand is function');
+console.log('Checking createArgument');
+check(typeof createArgument === 'function', 'createArgument is function');
 console.log('Checking createOption');
 check(typeof createOption === 'function', 'createOption is function');
 

typings/index.d.ts

@@ -249,6 +249,14 @@ declare namespace commander {
      */
     addCommand(cmd: Command, opts?: CommandOptions): this;
 
+    /**
+     * Factory routine to create a new unattached argument.
+     *
+     * See .argument() for creating an attached argument, which uses this routine to
+     * create the argument. You can override createArgument to return a custom argument.
+     */
+    createArgument(name: string, description?: string): Argument;
+
     /**
      * Define argument syntax for command.
      *

typings/index.test-d.ts

@@ -345,3 +345,7 @@ expectType<boolean>(baseArgument.variadic);
 // Argument methods
 // name
 expectType<string>(baseArgument.name());
+
+// createArgument
+expectType<commander.Argument>(program.createArgument('<name>'));
+expectType<commander.Argument>(program.createArgument('<name>', 'description'));