The Impact of Pattern Use on Design Quality
Ralf Reißing · 2001
The pattern community promises that using design patterns enhances design quality. So, if we have two similar designs A and B for the same problem, B using design patterns and A not using design patterns, B should have higher quality than A. However, if we apply "classic" object-oriented design metrics to both designs, the metrics tell us that design A is better -- mostly because it has less classes, operations, inheritance, associations, etc. So the question is: who is wrong? The metrics or the pattern community? Do we have the wrong quality metrics for object-oriented design? Or does using patterns in fact make a design worse, not better? 1 The Problem The correct use of design patterns is supposed to increase the quality of designs. Because design quality can be measured by quality metrics, the use of design patterns should lead to better measures. However, many common object-oriented design metrics indicate lower quality if design patterns are used. The following example shows s...