he Class system in [Mootools](http://mootools.net) a exceptionally powerful for the little amount of code that it is comprised of. A large part of that power comes from the Mutator system. A Mutator can be thought of a lot like a plug-in. However unlike most plug-ins that are executed at run time, Mootools Mutators are executed at the time a class is [actually defined](http://github.com/mootools/mootools-core/blob/master/Source/Class/Class.js#L76) altering the end result of the class

A Mutator is nothing more than a JavaScript function that has access to the internals of the class it is attached to. These functions are stored in a Mutators namespace in the Mootools library.

rivate and protected class methods can come in handy when creating complex applications. While JavaScript doesn't provide these features natively, [Mootools](http://mootools.net) provides a mechanism to define protected methods on a class. Protected means that the function can only be called by the originating class or a sub-class of the originating class. An attempt to call a protected function by a different class or from an instance of the class would result in error. Here is how you do that with a mootools classs:

var SecretClass = new Class({
	Implements:[Options]
	, initialize: function( options ){
		this.setOptions( options );
		var s = this.protectedMethod();
	}

	/**
	 * A regular class method 
	 */
	,publicMethod: function( name ){
		alert("Hello" + ( name || "world") + "!"

ython comes standard with an interesting module called, itertools, which provides a set of functions that make performing complex computations that revolve around iteration much easier. It is actually a invaluable set of tools to have at your disposal when you get comfortable with them. The module itself can work with anything that implements the iterator interface. An iterator is an object wrapper around some sequence that exposes a method called next. When the next method is called, the iterator should return the next item in the sequence and throws a StopIteration exception when there is nothing left in the sequence. While JavaScript doesn't offer anything that would resemble an iterator, that are actually very simple to implement when

he [MooTools](http://www.mootools.net) ( My Object Orientated Tools ) JavaScript framework is a pretty sweet piece of software. It's goal is to make developing with JavaScript easier. It provides large set of tools for building complex JavaScript applications. There are a lot of hidden [goodies](http://www.youtube.com/watch?v=6nOVQDMOvvE) tucked away in the framework that kick off one of those ["AHa!" moments](http://en.wikipedia.org/wiki/Eureka_effect). One of those goodies is the toElement method on classes. One of those goodies is the **toElement** method on classes.

The Class' method, toElement, works in tandem with the MooTools document.id ( $ ) method. In most cases, Classes center around a DOM element for some reason