An empirical study on the evolution of design patterns

Design patterns are solutions to recurring design problems,conceived to increase benefits in terms of reuse, code qualityand, above all, maintainability and resilience to changes.This paper presents results from an empirical study aimedat understanding the evolution of design patterns in three open source systems, namely JHotDraw, ArgoUML, andEclipse-JDT. Specifically, the study analyzes how frequently patterns are modified, to what changes they undergo andwhat classes co-change with the patterns. Results showhow patterns more suited to support the application purpose tend to change more frequently, and that different kind of changes have a different impact on co-changed classes and a different capability of making the system resilient tochanges.