oo.js

/**
 * Object Oriented JS Utils
 */
var oo = {
  /**
   * `methods` parameter is optional, if base is not 
   * defined assume it was defined in method's place,
   * that way this method can be called as follows:
   *
   * `var Class = oo.extend(function () {}, BaseClass);`
   *
   * Or if you need to also specify shared methods
   *
   * `var Class = oo.extend(function () {}, {
   * 'myMethod': function () {} }, BaseClass);`
   */
  extend: function (constructor, methods, base) {
    if(base === undefined) {
      base = methods;
      methods = undefined;
    }

    // A generic constructor function we'll return from this method
    function o() {
      var self = this,
      baseRan = false;
      //base.apply(this, args);
      self._base = function () { 
        base.apply(self, 
            Array.prototype.slice.call(arguments, 0));
        baseRan = true;
      };
      constructor.apply(self, 
          Array.prototype.slice.call(arguments, 0));

      if(!baseRan) {
        throw 'Forgot to call _base()?';
      }
    }

    o.prototype = Object.create ? Object.create(base.prototype) : new base();
    o.prototype.constructor = o;

    // _super is a "private" variable all instances have, and 
    // whenever an attribute from the child object overrides an
    // attribute from the base object, the base method is stored
    // in _super, so you can access it inside your object as
    // `this._super.myBaseMethod`.
    o.prototype._super = {};

    // If the methods arguments is defined it must be an object
    // literal with all the methods for this "class", store them
    // in the `prototype` so they are stored in a single place in
    // memory, meaning all instances will share the methods
    if(methods !== undefined && typeof methods === 'object') {
      for(var attr in methods) {
        if(o.prototype[attr]) {
          o.prototype._super[attr] = o.prototype[attr];
        }

        o.prototype[attr] = methods[attr];
      }
    }

    // Finally return the generated constructor function
    return o;
  }
};