Comprehension of Object-Oriented Software Cohesion: The Empirical Quagmire

It is a little over ten years sinc e Chidamber and Kemerer's obje ct-oriented (OO) metric suite which included the Lack of Cohesion Of Methods (LCOM) metric was rst proposed [9]. Despite considerable e ort both theoretically and empirically sinc e then, the softwar eengineering community is still no ne arer nding a generally ac cepte d de nition or me asure of OO cohesion. Y et,achieving highly cohesive software is a cornerstone of software comprehension and hence, maintainability. In this pap er, we suggest a number of suppositions as to why a de nition has eluded (and we feel will continue to elude) us. We supp ortthese suppositions with empirical evidence from three large C++ systems and a cohesion metric based on the parameters of the class methods; we also draw from other related work. Two major conclusions emerge from the study. Firstly, any sensible cohesion metric does at least provide insight into the featur es of the systems being analysed. Se condly however, and less reassuringly, the deeper the investigative search for a de nitive measur eof cohesion, the more problematic its understanding becomes; this casts serious doubt on the use of cohesion as a meaningful featur eof obje ct-orientation and its viability as a tool for software comprehension.