easejs/lib/class.js

/**
 * Contains basic inheritance mechanism
 *
 *  Copyright (C) 2010 Mike Gerwitz
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @author  Mike Gerwitz
 * @package core
 */


/**
 * Default class implementation
 *
 * @return undefined
 */
var Class = function()
{
};


/**
 * Mimics class inheritance
 *
 * This method will mimic inheritance by setting up the prototype with the
 * provided base class (or, by default, Class) and copying the additional
 * properties atop of it.
 *
 * The class to inherit from (the first argument) is optional. If omitted, the
 * first argument will be considered to be the properties list.
 *
 * @return  {Object}  extended class
 */
var extend = function()
{
    var args  = Array.prototype.slice.call( arguments ),
        props = args.pop() || {},
        base  = args.pop() || Class,

        prototype = new base(),
        new_class = function()
        {
            if ( this.__construct instanceof Function )
            {
                this.__construct.apply( this, arguments );
            }
        };

    new_class.prototype   = prototype;
    new_class.constructor = new_class;

    return new_class;
}


/**
 * Creates a class, inheriting either from the provided base class or the
 * default base class
 *
 * @param  {Object}  base  object to extend (extends Class by default)
 *
 * @return  {Object}  extended class
 */
exports.extend = function( base )
{
    return extend.apply( this, arguments );
}


/**
 * Shorthand for extending classes
 *
 * This method can be invoked on the object, rater than having to call
 * Class.extend( this ).
 *
 * @param  {Object}  props  properties to add to extended class
 *
 * @return  {Object}  extended class
 */
Object.defineProperty( Class.prototype, 'extend',
{
    value: function( props )
    {
        return extend( this, props );
    },

    enumerable:   false,
    writable:     false,
    configurable: false,
} );