A unified framework for cohesion measurement in object-oriented systems

Abstract

The increasing importance being placed on software measurement has lead to an increased amount of research developing new software measures. Given the importance of object-oriented development techniques, one specific area where this has occurred is cohesion measurement in object-oriented systems. However, despite a very interesting body of work, there is little understanding of the motivation and empirical hypotheses behind many of these new measures. It is often difficult to determine how such measures relate to one another and for which application they can be used. As a consequence, it is very difficult for practitioners and researchers to obtain a clear picture of the state-of-the-art in order to select or define cohesion measures for object-oriented systems. This situation is addressed and clarified through several different activities. First, a standardized terminology and formalism for expressing measures is provided which ensures that all measures using it are expressed in a fully consistent and operational manner. Second, to provide a structured synthesis, a review of the existing approaches to measure cohesion in object-oriented systems takes place. Third, a unified framework, based on the issues discovered in the review, is provided and all existing measures are then classified according to this framework. Finally, a review of the empirical validation work concerning existing cohesion measures is provided.This paper contributes to an increased understanding of the state-of-the-art: a mechanism is provided for comparing measures and their potential use, integrating existing measures which examine the same concepts in different ways, and facilitating more rigorous decision making regarding the definition of new measures and the selection of existing measures for a specific goal of measurement. In addition, our review of the state-of-the-art highlights several important issues: (i) many measures are not defined in a fully operational form, (ii) relatively few of them are based on explicit empirical models as recommended by measurement theory, and (iii) an even smaller number of measures have been empirically validated; thus, the usefulness of many measures has yet to be demonstrated.

Where the Truth Lies: AOP and Its Impact on Software Modularity

“…Briand et al demonstrate [4] that LCOM is neither normalized nor monotonic. Normalization is intended to allow for comparison between modules of different size.…”

“…The other problem with LCOM is that it does not differentiate modules well [1]. This is partly due to the fact that LCOM is set to zero whenever there are more pairs of methods which use an attribute in common than pairs of methods which do not [4]. In addition, the presence of access methods artificially decreases this metric.…”

“…In addition, the presence of access methods artificially decreases this metric. Access methods typically reference only one attribute, namely the one they provide access to, therefore they increase the number of pairs of methods in the class that do not use attributes in common [4]. The CBO metric also indicates inherent weakness.…”

“…In our defence we would point out that the OO community has yet to arrive at a consensus about the appropriate measurement of coupling and cohesion. The interested reader is referred to [4,5], and [20] where an extensive surveys have been presented.…”

Predicting the Size of Test Suites from Use Cases: An Empirical Exploration

“…It is used to predict the dependent variable from a set of independent variables to determine the percent of variance in the dependent variable explained by the independent variables [1,7,37]. This technique has been widely applied to the prediction of fault-prone classes [e.g., 11,12,20,26,33,37]. LR is of two types: univariate LR and multivariate LR.…”