From DevShed today, there's a new tutorial concerning interfaces in PHP5 and how to define some of your own.

In this tutorial, I’ll introduce the use of user-defined interfaces in PHP5, covering the basics of its theory along with the implementation of different examples, aimed specifically at demonstrating its functionality in real applications.

Before we get started, a few items with be required. You should have at least a basic familiarity with the PHP5 syntax, along with an intermediate knowledge of concepts related to object-oriented programming. Therefore, having defined the objectives of the article, let’s move on to learning about user-defined interfaces in PHP5.

They still define what the interfaces are before they get started, but shortly there after they jump right in creating some other interfaces: DeSerializer, PostSaver, and MySQLCache. They tie them together in the end to make a functional example...