Constants Implementation

constant.js

define( "constants", [ "utils" ], function( Utils ) {
	/**
	 * _constants is a private object that will hold the
	 * constant values. Hidden behind a closure to prevent
	 * modules from changing "constant" values once set.
	 * @type {Object}
	 */
	var _constants = {},

	/**
	 * Constants is the constructor for the Constants "class". It
	 * takes an object of "constants" as its only argument and sets
	 * the private _constants variable.
	 *
	 * @param {object} constants Constants to be set.
	 */
	Constants = function( constants ) {
		_constants = constants;
	};

	/**
	 * getConstant attempts to retrieve a constant from set constants.
	 * Takes an optional fallback if the constant isn't available.
	 *
	 * @param  {string} name     "Name" of the constant. Accepts dot notation
	 *                           for nested values.
	 * @param  {mixed}  fallback Fallback value if constant can't be found.
	 * @return {mixed}           Value of the desired constant (or the default).
	 */
	Constants.prototype.getConstant = function( name, fallback ) {
		var args = [ _constants, name ];

		if ( fallback !=== undefined ) {
			args.push( fallback );
		}
		return Utils.getValue.apply( Utils, args );
	};

	return Constants;
} );

/**
 * Consuming applications can define their own constant modules as needed.
 */
define( "hdmconstants", [ "constants" ], function( Constants ) {
	return new Constants( {
		FOO: "foo",
		bar: {
			FOO: "bar",
		},
	} );
} );

/**
 * Consuming application modules can access constants with the magic getter.
 */
define( "foomodule", [ "hdmconstants" ], function( Constants ) {
	return Backbone.View.extend( {
		doTheThing: function() {
			console.log( Constants.getConstant( "FOO" ) ); // "foo"
			console.log( Constants.getConstant( "bar.FOO" ) ); // "bar"
		},
	} );
} );