What is a Design Pattern?
Each pattern Describes a problem which occurs over and over again in our
environment ,and then describes the core of the problem
Novelists, playwrights and other writers rarely invent new stories.
Often ideas are reused, such as the “Tragic Hero” from Hamlet or Macbeth.
Designers reuse solutions also, preferably the “good” ones
– Experience is what makes one an ‘expert’
Problems are addressed without rediscovering solutions from scratch.
“My wheel is rounder.
Design Patterns are the best solutions for the re-occurring problems in the application
Nearly a universal standard.
Responsible for design pattern analysis in other areas, including GUIs.
Mainly used in Object Oriented programming.
Design Pattern Elements
1. Pattern Name
Handle used to describe the design problem.
Eases design discussions.
Evaluation without implementation details.
Describes when to apply a pattern.
May include conditions for the pattern to be applicable.
Symptoms of an inflexible design or limitation.
Describes elements for the design.
Includes relationships, responsibilities, and collaborations.
Does not describe concrete designs or implementations.
A pattern is more of a template.