A Comparative Study on the Effectiveness of Patterns in Software Libraries and Standalone Applications

The existence of design pattern instances is often regarded as an indication of elaborate software design, since patterns have been reported in many studies as techniques that improve software quality properties. Driven by the widespread belief that software libraries excel in terms of design quality compared to standalone applications, this study investigates first whether this claim is confirmed and second whether the improved quality can be attributed to the use of patterns. In particular we examine: (a) whether libraries exhibit improved design quality in terms of metrics compared to standalone applications, (b) the intensity of use of design patterns in the two software categories and (c) whether there is any correlation of design patterns usage and design quality at system level. The results of the study suggest that, some of the quality properties are improved in library software although no significant difference in the use of patterns have been observed. Moreover, there is an important number of GoF design patterns that appears to be correlated to software quality metrics.