Empirical insight into the context of design patterns: Modularity analysis

Design patterns are common solutions to specific design problems. There are many claimed benefits of the application of design patterns on design quality. This paper empirically evaluates and compares the modularity of design patterns in object-oriented software. Coupling and cohesion of classes that participate in design patterns were compared with those that do not participate. We used CBO and LCOM metrics as proxy measures for coupling and cohesion respectively. Data were collected from five open source systems, and analyses were conducted at both the design and pattern levels. At the design level, we compared the modularity of participant versus non-participant classes in design patterns, whereas at the pattern level, we compared the modularity of the classes in each pattern. The results indicate that the classes that participate in design patterns are more coupled and less cohesive than the non-participant classes at both levels.