DevShed is continuing on with their series looking at advanced concepts of object oriented PHP with this new tutorial. It's part three of four parts, looking this time at polymorphism and design patterns in PHP.

Last week, we continued our discussion of the object-oriented features of PHP 5 by taking a first look at design patterns. This week, we will continue looking at design patterns, and examine polymorphism. This article, the third of four parts, is excerpted from chapter two of the book Advanced PHP Programming, written by George Schlossnagle.

They cover some of the more handy features OOP in PHP5, including interfaces, type hinting, the factory pattern and the singleton pattern.