Towards Cohesion-based Metrics as Early Quality Indicators of Faulty Classes and Components

Measuring structural design properties of an object-oriented system is a promising approach towards early quality assessments. In object-oriented systems, cohesion is an important factor of objectoriented design quality. A few researchers refer cohesion to the degree of the relatedness of the members in a class. In an object-oriented system, classes and components are key early artifacts that lay the foundation of an object-oriented system. A few cohesion metrics have been proposed to quantify the cohesiveness of classes in an object-oriented system. In this paper, we attempt to quantify the amount of cohesion in classes and components via a suite of object-oriented design metrics. This paper proposes four object-oriented design metrics to evaluate cohesion at the class and component level. The metrics are augmented based on different definitions of LCOM. The metrics are normalized to produce values in the range [0..1], thus yielding more meaningful values than other cohesion metrics such as LCOM1 and LCOM4. The proposed metrics attempt to evaluate whether an artifact (i.e. class or component) represents one abstraction (good) or multiple abstractions (bad). If the artifact represents multiple abstractions, it should be split up into multiple artifacts (i.e. classes and components).