On the Properties of Design-Relevant Classes for Design Anomaly Assessment

Several object-oriented systems have their respective designs documented by using only a few design-relevant classes, which we will refer to as key classes. In this paper, we automatically detect key classes, and investigate some of their properties, and evaluate their role for assessing design. We propose focusing on such classes to make design decisions during maintenance tasks as those classes of this type are, by definition, more relevant than non-key classes. First, we show that key classes are more prone to bad smells than non-key classes. Although, structural metrics of key classes tend to be, in general, higher than non-key classes, there are still a significant set of non-key classes with poor structural metrics, suggesting that prioritizing design anomaly assessment using key classes would likely to be more effective.