Simple Ruby-style inheritance for JavaScript

def.js

/*
 *    def.js: Simple Ruby-style inheritance for JavaScript
 *
 *    Copyright (c) 2010 Tobias Schneider
 *    This script is freely distributable under the terms of the MIT license.
 *
 *
 *    Example:
 *    
 *      def ("Person") ({
 *          init: function(){ ... }
 *      });
 *
 *      def ("Ninja") << Person ({
 *          init: function(){ ... }
 *      });
 */

def = function(className){
    var base = window[className] = function(){
        if(this.constructor === base){ if(this.init){ this.init(arguments); } }
        else{
            def._super = base;
            def._props = arguments[0];
        }
    },
    props = function(keyValues){
        if(def._super){
            var superclass = def._super;
            def._super = def._props = null;
            props(superclass.prototype);
            props(keyValues);
        }else{
            var proto = base.prototype;
            for(var key in keyValues){ proto[key] = keyValues[key]; }
        }
    };
    props.valueOf = function(){
        this(def._props);
    };
    return props;
};