I’ve recently be challenged by freshly written code at my company where they used the factory pattern.  This led me to research into why one would want to use it.  In a lot of my research, they discourage it until it is really needed because it adds complexity with the additional classes and creation logic.

Here are some of my additional thoughts:

• This pattern hides the creation of an object.
• Useful when creating the object involves multiple steps.
• Centralizes object creation so that if it needs to change it only needs to be changed in one place.
• Useful if you have a lot of code that checks if object type is this…then do this.  This really is one of the most useful features I see.
• It could be used for unit testing to switch in test data in place of live data.
• Can bring unnecessary complexity: http://www.oodesign.com/factory-pattern.html , also agile principles, patterns, and practices in c#, Robert Martin.
• Case Switch pattern is easier and more useful in that you don’t have to create a method for each and the calling logic doesn’t have to know what type of object it is dealing with.