Mike Weiner has put together an article for PHPBuilder.com that's posted today showing a bit more object-oriented solution to validating the user submitted data in your forms:

Whether it is for database submission, emailing, or for some other purpose, forms represent the primary means of enabling a user to send data to an application. As a result, it is important to have control over the data collected by your forms, which will aid in the creation of streamlined, error-free applications.

He lays out the validation method in a graphic going with a generic validation class that then calls the various validation methods (like phone or email) as needed. The "validation set" manages which validations are to be run on which form elements. Example code for each of the bits making up the structure and the implementation are provided.

In a new post to the Zend Developer Zone, Brett Zamir has posted a new tutorial that talks about using the Smarty templating system to create what he calls the HYSOCAMTT templating approach ("Have-Your-Separation-Of-Concerns-And-Mix-Them-Too".

This article aims to highlight a approach which allows one to separate everything from one's business logic to one's design logic, to XHTML from CSS, one's Javascript from the page structure, etc., while at the same time being able to be lazy and include, for example, CSS information within the same document (template) as one's XHTML

The tutorial uses an extension for Smarty called SmartyDocB that makes the documentation side much easier. He works through the templating process and includes some of the code for the .tpl files to get you started.

He also includes some future goals for his idea, a mention of XSL templating, XQuery and the potential for templating across programming languages to make your site even more flexible.