The StarTutorial.com site has posted the next in their "Understanding Design Patterns" series of tutorials today. In this latest post they cover the Factory design pattern.
[The Factory design pattern provides] an interface for creating families of related or dependent objects without specifying their concrete classes.
They use the same fictional business as in the previous articles to put the pattern in a more "real world" situation. The goal is to create several "toy factories" that can build "toy" objects based on certain requirements: either cars or helicopters. The post starts with the creation of an abstract factory class and shows the concrete implementations of one for each type of toy. These concrete classes include basic properties about the toy and functionality to build out the basics (ex: a car has four wheels, a helicopter has rotors).