opt

opt

revision 0.0.10

Why another command line argument processor?

There are three reasons I created opt.js

• I wanted to simplify the boilerplate I used with JSON based configuration files including handling a set of search paths (e.g. look sequentially in
• I wanted a very simple command line option parser that included automatically generating a help page (I'm forgetful about updating docs outside of
• I wanted a simple http route process that generate docs like I used for the command line

That was my itch. There are many file example of options parsing libraries in Node but they didn't quite scratch the itch I had.

Overview

opt is a toolkit for building either command line programs and RESTful web services. It uses a common pattern for setting up and processing JSON based configuration files, command line options and RESTful API calls.

Using the module is usually invoked by

	var opt = require("opt").create();

It is available from github at https://github.com/rsdoiel/opt and can be installed using npm

	npm install opt

Examples Code

The following examples build by topics

• configuration processing
• command line option processing
• a RESTful Hello World API

Config Example

This is the synchronous version.

	/*jslint node: true */
	"use strict";

	var path = require("path"),
	    opt = require("../opt").create();

	    var config = { name: "fred", email: "[e-mail]" },
	    	search_paths = [ "config-example-1.conf",
			path.join(process.env.HOME, ".config-examplerc"),
			"/usr/local/etc/config-example.conf",
			"/usr/etc/config-example.conf",
			"/etc/config-example.conf" ];

	console.log("Unprocessed config:", config);
	opt.config(config, search_paths);

	opt.on("ready", function (config) {
		// config should now hold the merge configuration
		// from default_config and the first configuration file 
		// found in the search path list.
		console.log("Processed config: ", config);
	});

Adding Option processing

Display a help message with -h and --help on the command line.

	/*jslint node: true */
	"use strict";
	
	var path = require("path"),
		opt = require("../opt").create();
	
	var config = { name: "fred", email: "[e-mail]" },
		search_paths = [ "config-example-1.conf",
				path.join(process.env.HOME, ".config-examplerc"),
				"/usr/local/etc/config-example.conf",
				"/usr/etc/config-example.conf",
				"/etc/config-example.conf" ];
	
	console.log("Unprocessed config:", config);
	opt.config(config, search_paths);
	
	opt.optionHelp("USAGE node " + path.basename(process.argv[1]),
		"SYNOPSIS: Demonstrate how opt works to parse command line options.\n\n\t\t node " + path.basename(process.argv[1]) + " --help",
		"OPTIONS:",
		" copyright (c) 2012 all rights reserved\n" +
		" Released under New the BSD License.\n" +
		" See: http://opensource.org/licenses/bsd-license.php\n");
	
	
	opt.on("ready", function (config) {
		opt.option(["-n", "--name"], function (param) {
			if (param.trim()) {
				config.name = param.trim();
			}
		}, "Set the name parameter");
	
		opt.option(["-e", "--email"], function (param) {
			if (param.trim()) {
				config.email = param.trim();
			}
		}, "Set the email parameter");
		
		opt.option(["-g", "--generate"], function (param) {
			if (param.trim()) {
				fs.writeFile(param.trim(), JSON.stringify(config));
			} else {
				console.log(JSON.stringify(config));
			}
			process.exit(0);
		}, "Generate a configuration file");
		
		opt.option(["-h", "--help"], function () {
			opt.usage();
		}, "This help document.");
	
		opt.optionWith(process.argv[1]);
	
		// config should now hold the merge configuration
		// from default_config and the first configuration file 
		// found in the search path list.
		console.log("Processed config: ", config);
	});

A simple web server API

	// Importing some modules
	var util = require("util"),
		http = require("http"),
		path = require("path"),
		// import and create the opt object
		opt = require("../opt").create();
	
	// Define your configuration defaults and load your local configuration
	// file or it.
	opt.config({ host: "localhost", port: 8080, name: "John Doe"},
		[ "/etc/helloworld.json", path.join(process.env.HOME, "etc/helloworld.json") ]);
	
	// When your configuration is "ready" parse the command lines
	// and setup your RESTful hello world web service
	opt.on("ready", function (config) {
		// Setup how your help page will look
		opt.optionHelp("USAGE node " + path.basename(process.argv[1]),
			"SYNOPSIS:\n\tThis is a simple hello world web service.",
			"OPTIONS:",
			"this is an opt demo");
	
		// Define your command line options
		opt.option(["-H", "--host"], function (hostname) {
			config.host = hostname.trim();
		});
		opt.option(["-p", "--port"], function (portname) {
			config.port = Number(portname.trim());
		});
		opt.option(["-n", "--name"], function (name) {
			config.name = name.trim();
		});
		opt.option(["-h", "--help"], function () {
			opt.usage();
		});
	
		// Define you restful service
		var helloworld = function (req, res, matching, rule_no) {
			res.writeHead(200, {"content-type": "text/plain"});
			res.end("Hello " + config.name + ".\nThis is what I found: " + util.inspect(matching) + "\nRule No.:" + rule_no);
		};
		opt.rest("get", new RegExp("^$|^/$|^/index.html|^/helloworld.html"), helloworld);
	
		var status404 = function (req, res) {
			res.writeHead(404, {"content-type": "text/plain"});
			res.end("File not found. " + req.url);
		};
		opt.rest("get", new RegExp("^/*"), status404);
	
		// Process your command line args.
		opt.optionWith(process.argv);
	
		// Process your restful requets
		console.log("Configuration:", config);
		http.createServer(function (req, res) {
			console.log("request:", req.url);
			opt.restWith(req, res);
		}).listen(config.port, config.host);
		console.log("Web server listening on " + config.host + ":" + config.port);
	});