When to use factory patterns?

问题:

What is this factory all about and what are the advantages of using factory patterns? Does it give a plugable architecture? Why it is called "Factory"?

回答1:

It is factory since it is actually "Manufacturing" (Create) an object.

There's actually two kind of factory pattern defined by GoF:

1. Factory Method
2. Abstract Factory

Basically both of them tries to decouple the calling client from knowing the actual concrete implementation of the class/interface.

回答2:

You can find all you need by reading this PDF article