Abstract Factory

Provide an interface for creating interrelated object families, without specifying their concrete classes.

Consider, for instance, an application that runs on different graphic systems (e.g. Motif, Presentation Manager)

Each graphic element (window, button, etc.) must be created differently, depending on the system used.

To do this, an abstract class is used to create the graphic elements

A system must be independent of how its products are created, composed and represented

A system must choose one of several product families

The objects of a family must be used together, and we want to reinforce this constraint.

We want to propose a library of products, without showing their implementation

Clients do not know the implementation classes of the families

Switching between product groups becomes simple

The consistency within a product family is enhanced

It is difficult to add new product families.

Factories are Singletons

Factories define an interface, which can be implemented by a prototype or by a factory method

Definition of extensible factories

Design Patterns: Elements of Reusable Object-Oriented Software. Erich Gamma, Richard Helm,Ralph Johnson, and John Vlissides. Addison Wesley. October 1994.