On Inter-Method and Intra-Method Object-Oriented Class Cohesion

Cohesion has been a topic of interest since structured design [20, 23] in the 1970’s. Today, there are numerous researchers continuing this work into object-oriented designs [1, 3, 5, 7, 9, 10, 12, 13, 16, 18, 19, 22]. Most of the current research has focused on the interaction of methods within a class, the inter-method cohesion. In this paper we consider both the inter-method cohesion and the intra-method cohesion of a class. We have utilized the concept of program slice [21] and extended Functional Cohesion [2] to devise a new intra-method cohesion metric, ITRA-C, for measuring cohesion of each method within the class. This intra-method cohesion is based on the notion of effects and chaining in an effect-slice. We further combine the (inter-method, intra-method)-tuple into one combined Class Cohesion, which provides a quick view of bands of cohesion for classes. A sample of a commercial bank account class is then provided to illustrate these concepts and metrics.