Quantifying the effects of aspectual decompositions on design by contract modularization: a maintenance study

Abstract

Although it is assumed that the implementation of design by contract is better modularized by means of aspect-oriented (AO) programming, there is no empirical evidence on the effectiveness of AO for modularizing non-trivial design by contract code in realistic development scenarios. This paper reports a quantitative and qualitative case study that evolves a real-life application to assess various facets of the adequacy of aspects for modularizing the design by contract concern. Our evaluation focused upon a number of system changes that are typically performed during software maintenance tasks. The study was driven by an analysis of fundamental modularity attributes, such as separation of concerns, coupling, conciseness, and change propagation. We have found that AO techniques improved separation of concerns and the design stability between the design by contract code and base application code throughout the development scenarios. However, contradicting the general intuition, the AO versions of the system did not present significant gains regarding four classical size metrics we employed.