Design pattern (computer science)
Design patterns represent the accumulated knowledge of the community of software developers of standardised solutions to recurring problems.
They allow software developers to make use of the knowledge of past designers. Many design projects are confronted with similar problems that demand similar solutions. A design pattern is an abstraction of a solution for a particular class of problems. MVC or model view controller triad is a classical example of design pattern. It was introduced 1980 in the Smalltalk system.
The book that introduced the term design pattern to software development is Design Patterns: elements of reusable object-oriented software (commonly shortened to GoF -- Gang of Four a reference to the four authors) says:
- Design patterns solve specific design problems and make object-oriented designs more flexible and elegant, and ultimately reusable. They help designers reuse successful designs by basing new designs on prior experience. A designer who is familiar with such patterns can apply them immediately to design problems without having to rediscover them.
In computer programming
, the incredible gap
between amateurs and experts is partly a difference
. Experts have weathered a variety
of problems repeatedly. Typically experts end up with the same pattern to solve the problems as each other's. That is a design pattern. (GoF)
Each pattern comes up with the problem that happens again and again among programmers. Then it shows a typical solution for such a problem, if not the best solution, along with the trade-off, which is a convenient assessment to make prior to applying a potentially costly solution. It is important that patterns accompany a name because it makes possible to describe problems, solutions and talk about them with other folks.
For example the classical MVC pattern is actually a combination of three patterns listed below - Observer, Composite and Strategy. It is broadly used today.
Frequent problems that occur in programming are sometimes less commonly called anti-pattern.
See also amelioration pattern
Social / other
- Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides: Design Patterns, Addison-Wesley, 1995, hardcover, 395 pages, ISBN 0201633612, Design Patterns CD, 1997 ISBN 0201634988
- Frank Buschmann, Regine Meunier, Hans Rohnert, Peter Sommerlad, Michael Stal: Pattern-oriented Software Architecture, Volume 1: A System of Patterns, John Wiley & Sons Ltd., ISBN 0471958697
- Douglas Schmidt: Pattern-oriented Software Architecture. Volume 2: Patterns for Concurrent and Networked Objects, John Wiley & Sons Ltd., ISBN 0471606952
- Alan Shalloway, James R. Trott: Design Patterns Explained: A New Perspective on Object-Oriented Design, Addison-Wesley, ISBN 0201715945
- Martin Fowler: Patterns of Enterprise Application Architecture, Addison-Wesley, ISBN 0321127420