An Empirical Study on Maintainability Index of Software Design Patterns

While design patterns are widely used to enhance software quality, there is a need for empirical evidence to understand their impact on software maintainability. This study empirically investigates the maintainability index of object-oriented design patterns at three levels: design, pattern category, and individual patterns. Data were collected from five real-world software systems, which include a total of 63 instances of design patterns spanning 17 GoF design patterns. At the design level, the results show that classes implementing design patterns have a statistically significant higher maintainability index than those that do not. At the pattern category level, creational and structural design patterns exhibit a higher maintainability index compared to behavioral patterns. Finally, at the pattern level, the Builder, State, and Adapter patterns rank as the top three in terms of maintainability index.