Design Patterns Explained: A New Perspective on Object-Oriented Design

Field Notes: Using the Factory Method Pattern

In the classic implementation of the Abstract Factory, I had an abstract class define the methods to create a family of objects. I derived a class for each different family I could have. Each of the methods defined in the abstract class and then overridden in the derived classes were following the Factory Method pattern.

Sometimes it is useful to create a hierarchical class structure that is parallel to an existing class structure, with the new hierarchy containing some delegated responsibilities. In this case, it is important for each object in the original hierarchy to be able to instantiate the proper object in the parallel hierarchy. A Factory Method can be used for this purpose.

The Factory Method ...