Class.Occlude.js

/*
---

script: Class.Occlude.js

name: Class.Occlude

description: Prevents a class from being applied to a DOM element twice.

license: MIT-style license.

authors:
  - Aaron Newton

requires: 
  - Core:1.2.4/Class
  - Core:1.2.4/Element
  - /MooTools.More

provides: [Class.Occlude]

...
*/

Class.Occlude = new Class({

	occlude: function(property, element){
		element = document.id(element || this.element);
		var instance = element.retrieve(property || this.property);
		if (instance && !$defined(this.occluded))
			return this.occluded = instance;

		this.occluded = false;
		element.store(property || this.property, this);
		return this.occluded;
	}

});