The factory method pattern specifies how an object can defer creation of some internal data and leave the actual task of creation for the derived class. It is part of the original Gang of Four book.
Imagine a kid making cookies out of dough. They can do nothing until they invoke the factory method and say, Give me a cutter. So, you provide them with a cookie cutter (the result of the factory method), and they can finally start making cookies.
By implementing this approach, you can be flexible and select the appropriate cookie shape for the occasion. Output from the factory method therefore changes the final result.
The functionality of this pattern, as described in the original Design Patterns publication, looks very similar to the dependency injection approach, but implemented with pure object-oriented tools. This section will mostly focus on...