CSC/ECE 517 Fall 2010/ch7 7d EC

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Introduction to Design Patterns

A design pattern is a type of technique that developers use to create good software design. There are many design patterns available, and they share common benefits. The benefits of design patterns include [1] :

     1. Code is more accessible and understandable.
     2. Use of common vocabulary to help collaboration among developers.
     3. Helps people understand the system more quickly.
     4. Easier to modify system.

GRASP

GRASP stands for General Responsibility Assignment Software Patterns and consists of several design patterns for assigning responsibility and relationships between classes and objects in object-oriented design.

Some of the patterns in GRASP include Information Expert, Creator, Controller, Low Coupling, High Cohesion, Polymorphism, Pure Fabrication, Indirection, and Protected Variations [2].

In this article, we will focus on the Indirection Pattern.

The Indirection Pattern

The Indirection Pattern supports low coupling and code reuse by using a mediator object in between two objects.

A very simple diagram below illustrates the relationship between objects in the indirection pattern.