CSC/ECE 517 Fall 2012/ch2b 2w57

Abstract Factory: A directory of sites

The essence of the Abstract Factory Pattern is to "Provide an interface for creating families of related or dependent objects without specifying their concrete classes".

In this wiki, we provide an explanation of the Abstract Factory pattern along with links to useful websites that would explain this design pattern in more detail.

Overview

The abstract factory pattern is a software creational design pattern that provides a way to encapsulate a group of individual factories that have a common theme without specifying their concrete classes. In normal usage, the client software creates a concrete implementation of the abstract factory and then uses the generic interfaces to create the concrete objects that are part of the theme. The client does not know (or care) which concrete objects it gets from each of these internal factories, since it uses only the generic interfaces of their products. This pattern separates the details of implementation of a set of objects from their general usage and relies on object composition, as object creation is implemented in methods exposed in the factory interface.

Motivation

Modularization is a big issue in today's programming. Programmers all over the world are trying to avoid the idea of adding code to existing classes in order to make them support encapsulating more general information. Take the case of a information manager which manages phone number. Phone numbers have a particular rule on which they get generated depending on areas and countries. If at some point the application should be changed in order to support adding numbers form a new country, the code of the application would have to be changed and it would become more and more complicated.

In order to prevent it, the Abstract Factory design pattern is used. Using this pattern a framework is defined, which produces objects that follow a general pattern and at runtime this factory is paired with any concrete factory to produce objects that follow the pattern of a certain country. In other words, the Abstract Factory is a super-factory which creates other factories (Factory of factories).

References

• ^ [|Gamma, Erich[1]]; Richard Helm, Ralph Johnson, John M. Vlissides (2009-10-23). "Design Patterns: Abstract Factory". informIT. Archived from the original on 2009-10-23. Retrieved 2012-05-16. "Object Creational: Abstract Factory: Intent: Provide an interface for creating families of related or dependent objects without specifying their concrete classes."

• a b Freeman, Eric; Freeman, Elisabeth; Kathy, Sierra; Bert, Bates (2004). Hendrickson, Mike. ed (paperback). Head First Design Patterns. 1. O'REILLY. p. 156. ISBN 978-0-596-00712-6. Retrieved 2012-09-12.