The conceptual cohesion of classes

While often defined in informal ways, software cohesion reflects important properties of modules in a software system. Cohesion measurement has been used for quality assessment, fault proneness prediction, software modularization, etc. Existing approaches to cohesion measurement in object-oriented software are largely based on the structural information of the source code, such as attribute references in methods. These measures reflect particular interpretations of cohesion and try to capture different aspects of cohesion and no single cohesion metric or suite is accepted as standard measurement for cohesion. The paper proposes a new set of measures for the cohesion of individual classes within an OO software system, based on the analysis of the semantic information embedded in the source code, such as comments and identifiers. A case study on open source software is presented, which compares the new measures with an extensive set of existing metrics. The differences and similarities among the approaches and results are discussed and analyzed.