Parse argument conventions

Readme.md

@@ -32,6 +32,7 @@ Read this in other languages: English | [简体中文](./Readme_zh-CN.md)
     - [.help(cb)](#helpcb)
   - [Custom event listeners](#custom-event-listeners)
   - [Bits and pieces](#bits-and-pieces)
+    - [.parse() and .parseAsync()](#parse-and-parseasync)
     - [Avoiding option name clashes](#avoiding-option-name-clashes)
     - [TypeScript](#typescript)
     - [Node options such as `--harmony`](#node-options-such-as---harmony)
@@ -598,6 +599,24 @@ program.on('command:*', function (operands) {
 
 ## Bits and pieces
 
+### .parse() and .parseAsync()
+
+The first argument to `.parse` is the array of strings to parse. You may omit the parameter to implicitly use `process.argv`.
+
+If the arguments follow different conventions than node you can pass a `from` option in the second parameter:
+
+- 'node': default, `argv[0]` is the application and `argv[1]` is the script being run, with user parameters after that
+- 'electron': `argv[1]` varies depending on whether the electron application is packaged
+- 'user': all of the arguments from the user
+
+For example:
+
+```js
+program.parse(process.argv); // Explicit, node conventions
+program.parse(); // Implicit, and auto-detect electron
+program.parse(['-f', 'filename'], { from: 'user' });
+```
+
 ### Avoiding option name clashes
 
 The original and default behaviour is that the option values are stored

index.js

@@ -100,6 +100,8 @@ class Command extends EventEmitter {
     this.options = [];
     this._allowUnknownOption = false;
     this._args = [];
+    this.rawArgs = null;
+    this._scriptPath = null;
     this._name = name || '';
     this._optionValues = {};
     this._storeOptionsAsProperties = true; // backwards compatible by default
@@ -620,19 +622,68 @@ class Command extends EventEmitter {
   /**
    * Parse `argv`, setting options and invoking commands when defined.
    *
-   * @param {Array} argv
+   * The default expectation is that the arguments are from node and have the application as argv[0]
+   * and the script being run in argv[1], with user parameters after that.
+   *
+   * Examples:
+   *
+   *      program.parse(process.argv);
+   *      program.parse(); // implicitly use process.argv and auto-detect node vs electron conventions
+   *      program.parse(my-args, { from: 'user' }); // just user supplied arguments, nothing special about argv[0]
+   *
+   * @param {string[]} [argv] - optional, defaults to process.argv
+   * @param {Object} [parseOptions] - optionally specify style of options with from: node/user/electron
+   * @param {string} parseOptions.from - where the args are from: 'node', 'user', 'electron'
    * @return {Command} for chaining
    * @api public
    */
 
-  parse(argv) {
-    // store raw args
-    this.rawArgs = argv;
+  parse(argv, parseOptions) {
+    if (argv !== undefined && !Array.isArray(argv)) {
+      throw new Error('first parameter to parse must be array or undefined');
+    }
+    parseOptions = parseOptions || {};
+
+    // Default to using process.argv
+    if (argv === undefined) {
+      argv = process.argv;
+      if (process.versions && process.versions.electron) {
+        parseOptions.from = 'electron';
+      }
+    }
+    this.rawArgs = argv.slice();
+
+    // make it a little easier for callers by supporting various argv conventions
+    let userArgs;
+    switch (parseOptions.from) {
+      case undefined:
+      case 'node':
+        this._scriptPath = argv[1];
+        userArgs = argv.slice(2);
+        break;
+      case 'electron':
+        if (process.defaultApp) {
+          this._scriptPath = argv[1];
+          userArgs = argv.slice(2);
+        } else {
+          userArgs = argv.slice(1);
+        }
+        break;
+      case 'user':
+        userArgs = argv.slice(0);
+        break;
+      default:
+        throw new Error(`unexpected parse option { from: '${parseOptions.from}' }`);
+    }
+    if (!this._scriptPath && process.mainModule) {
+      this._scriptPath = process.mainModule.filename;
+    }
 
     // Guess name, used in usage in help.
-    this._name = this._name || path.basename(argv[1], path.extname(argv[1]));
+    this._name = this._name || (this._scriptPath && path.basename(this._scriptPath, path.extname(this._scriptPath)));
 
-    this._parseCommand([], argv.slice(2));
+    // Let's go!
+    this._parseCommand([], userArgs);
 
     return this;
   };
@@ -642,13 +693,24 @@ class Command extends EventEmitter {
    *
    * Use parseAsync instead of parse if any of your action handlers are async. Returns a Promise.
    *
-   * @param {Array} argv
+   * The default expectation is that the arguments are from node and have the application as argv[0]
+   * and the script being run in argv[1], with user parameters after that.
+   *
+   * Examples:
+   *
+   *      program.parseAsync(process.argv);
+   *      program.parseAsync(); // implicitly use process.argv and auto-detect node vs electron conventions
+   *      program.parseAsync(my-args, { from: 'user' }); // just user supplied arguments, nothing special about argv[0]
+   *
+   * @param {string[]} [argv]
+   * @param {Object} [parseOptions]
+   * @param {string} parseOptions.from - where the args are from: 'node', 'user', 'electron'
    * @return {Promise}
    * @api public
    */
 
-  parseAsync(argv) {
-    this.parse(argv);
+  parseAsync(argv, parseOptions) {
+    this.parse(argv, parseOptions);
     return Promise.all(this._actionResults);
   };
 
@@ -667,7 +729,7 @@ class Command extends EventEmitter {
     this._checkForMissingMandatoryOptions();
 
     // Want the entry script as the reference for command name and directory for searching for other files.
-    const scriptPath = this.rawArgs[1];
+    const scriptPath = this._scriptPath;
 
     let baseDir;
     try {

tests/command.parse.test.js

@@ -0,0 +1,54 @@
+const commander = require('../');
+
+// Testing some Electron conventions but not directly using Electron to avoid overheads.
+// https://github.com/electron/electron/issues/4690#issuecomment-217435222
+// https://www.electronjs.org/docs/api/process#processdefaultapp-readonly
+
+describe('.parse() user args', () => {
+  test('when no args then use process.argv and app/script/args', () => {
+    const program = new commander.Command();
+    const hold = process.argv;
+    process.argv = 'node script.js user'.split(' ');
+    program.parse();
+    process.argv = hold;
+    expect(program.args).toEqual(['user']);
+  });
+
+  // implicit also supports detecting electron but more implementation knowledge required than useful to test
+
+  test('when args then app/script/args', () => {
+    const program = new commander.Command();
+    program.parse('node script.js user'.split(' '));
+    expect(program.args).toEqual(['user']);
+  });
+
+  test('when args from "node" then app/script/args', () => {
+    const program = new commander.Command();
+    program.parse('node script.js user'.split(' '), { from: 'node' });
+    expect(program.args).toEqual(['user']);
+  });
+
+  test('when args from "electron" and not default app then app/args', () => {
+    const program = new commander.Command();
+    const hold = process.defaultApp;
+    process.defaultApp = undefined;
+    program.parse('customApp user'.split(' '), { from: 'electron' });
+    process.defaultApp = hold;
+    expect(program.args).toEqual(['user']);
+  });
+
+  test('when args from "electron" and default app then app/script/args', () => {
+    const program = new commander.Command();
+    const hold = process.defaultApp;
+    process.defaultApp = true;
+    program.parse('electron script user'.split(' '), { from: 'electron' });
+    process.defaultApp = hold;
+    expect(program.args).toEqual(['user']);
+  });
+
+  test('when args from "user" then args', () => {
+    const program = new commander.Command();
+    program.parse('user'.split(' '), { from: 'user' });
+    expect(program.args).toEqual(['user']);
+  });
+});

typings/commander-tests.ts

@@ -145,6 +145,8 @@ program.exitOverride((err):void => {
 });
 
 program.parse(process.argv);
+program.parse();
+program.parse(["foo"], { from: "user" });
 
 program.parseAsync(process.argv).then(() => {
   console.log('parseAsync success');

typings/index.d.ts

@@ -23,6 +23,10 @@ declare namespace commander {
   }
   type OptionConstructor = { new (flags: string, description?: string): Option };
 
+  interface ParseOptions {
+    from: "node" | "electron" | "user";
+  }
+
   interface Command {
     [key: string]: any; // options as properties
 
@@ -196,19 +200,37 @@ declare namespace commander {
 
     /**
      * Parse `argv`, setting options and invoking commands when defined.
+     * 
+     * The default expectation is that the arguments are from node and have the application as argv[0]
+     * and the script being run in argv[1], with user parameters after that.
      *
+     * Examples:
+     *
+     *      program.parse(process.argv);
+     *      program.parse(); // implicitly use process.argv and auto-detect node vs electron conventions
+     *      program.parse(my-args, { from: 'user' }); // just user supplied arguments, nothing special about argv[0]
+     * 
      * @returns Command for chaining
      */
-    parse(argv: string[]): Command;
+    parse(argv?: string[], options?: ParseOptions): Command;
 
     /**
-    * Parse `argv`, setting options and invoking commands when defined.
-    * 
-    * Use parseAsync instead of parse if any of your action handlers are async. Returns a Promise.
-    *
-    * @returns Promise
-    */
-    parseAsync(argv: string[]): Promise<any>;
+     * Parse `argv`, setting options and invoking commands when defined.
+     * 
+     * Use parseAsync instead of parse if any of your action handlers are async. Returns a Promise.
+     * 
+     * The default expectation is that the arguments are from node and have the application as argv[0]
+     * and the script being run in argv[1], with user parameters after that.
+     *
+     * Examples:
+     *
+     *      program.parseAsync(process.argv);
+     *      program.parseAsync(); // implicitly use process.argv and auto-detect node vs electron conventions
+     *      program.parseAsync(my-args, { from: 'user' }); // just user supplied arguments, nothing special about argv[0]
+     *
+     * @returns Promise
+     */
+    parseAsync(argv?: string[], options?: ParseOptions): Promise<any>;
 
     /**
      * Parse options from `argv` removing known options,