In following the theme of design patterns we’re starting this site off with, we’re talking about the Factory Pattern here. The Factory Pattern, true to it’s name, acts as a factory to produce objects depending on the parameters provided to it.
A common example of this are configuration objects. Suppose you’ve setup a configuration for you’re application to use an XML configuration file to run. Now, let’s say for some unknown reason, you need to use an INI file for configuration. Or, let’s say that today you’re using MySQL for database storage, but tomorrow, you might be forced to use Oracle.
Having to find where you create the instances of classes could be difficult, or maybe even impossible. The solution to this dilemma, is to use factory pattern to produce objects where any future ambiguity might cause a disaster.
Typically, the way a factory is implemented is to implement some sort of class that acts as a quasi-gateway to the object that’s needed. To keep things simple, we’ll assume we’re trying to get a database object and we need to not worry about the actual implementation of the database (more…)