A Practical Look at the Lack of Cohesion in Methods Metric

Software metrics for the procedural software development paradigm have been extensively studied. Metrics such as McCabe's cyclomatic complexity metric 1 and Halstead's Software Science metrics 2 are well known and frequently used to measure software complexity in the procedural paradigm. More recently, software metrics that are tailored to the measurement of design complexity in the object-oriented paradigm have been developed. Chidamber and Kemerer proposed a draft suite of software metrics for object-oriented software in 1991 3 that included six object-oriented design metrics based on measurement theory. This suite of metrics included depth of the inheritance tree (DIT), number of children (NOC), coupling between objects (CBO), response for a class (RFC), weighted methods per class (WMC), and lack of cohesion of methods (LCOM). The LCOM metric has been subject to multiple interpretations which can greatly influence the LCOM value derived for a particular class. This article compares and analyzes the definition and implementation variations of the LCOM metric, and provides an assessment of this metric. The multiple definitions of the LCOM metric currently in use include: 1) the original definition of the LCOM metric by Chidamber and Kemerer 3 2) the definition of the LCOM metric provided by Li and Henry 4,5 , 3) the redefinition of the Li and Henry version of the LCOM metric by Hitz and Montazeri 6 , and 4) the redefinition of their original LCOM metric by Chidamber and Kemerer.