Late last year CodeIgniter v1.7.2 was released with a lot of improvements and bug fixes. This version is now compatible with PHP5.3.0, they added is_php() to Common functions to facilitate PHP version comparisons, modified show_error() to allow sending of HTTP server response codes, and all internal uses now send proper status codes, Form helper improved and a new class which we are about to cover in this tutorial the Shopping Cart Class.
They walk you through some of the basics that the shopping cart class has to offer - adding items, removing them, updating the current item list. They show you how to create each piece of the MVC puzzle - the Product controller, a Cart controller and two basic views, one for the cart and the other for the products. They didn't create a model because they're not hooking it into a database/backend resource.