An entropy-based complexity measure for object-oriented designs

The use of entropy as a measure of information content has led to its use in measuring the code complexity of functionally developed software products; however, no similar capability exists for evaluating complexities of object-oriented systems using entropy. In this paper a new metric based on entropy as a complexity measure for object-oriented classes is defined and validated using several large commercial object-oriented projects. The metric is computed using information available in class definitions. The new complexity measure of classes is correlated with traditional complexity measures such as McCabe's cyclomatic metric and the number-of-defects metric, both of which were evaluated from the implementation of the methods of the classes. The correlation study used the final versions of the class definitions. The high degree of positive correlation between the entropy-based class definition measure and the traditional measures of class implementation complexity verify that the new entropy measure computed from class definitions can be used as a predictive measure for class implementation complexities provided the class definitions do not change significantly during the implementation. (C) 1999 John Wiley & Sons, Inc.