Selecting reusable stand-alone routines: a proposal and a case study

Almost daily engineers write, mainly from scratch, ad hoc programs suitable to solve very specific problems. In order to provide assistance to enginee rs willing to develop their programs through white-bon reuse, it is mandato ry to offer them repositories of software components populated with stand-a lone routines selected according to software metrics able to measure the co de complexity. Our selection approach is inspired to that previously adopte d by Caldiera and Basili in a well-known paper, indeed, we use the same cla ssical metrics, namely: volume, cyclomatic complexity and regularity. In es sence, this paper represents both a refinement and a replication of the exp eriment performed by Caldiera and Basili, being the domain of the software investigated and the structure of the software itself the two major differe nces. In order to carry out the experiment, it was necessary to adapt the e xtremes of the values of the metrics mentioned above to our reference conte xt which is very different from that Caldiera and Basili referred to. The a daptation was not trivial because in the case of routines being part of sof tware libraries it is not possible to proceed as they did. In this paper, a general strategy suitable to "calibrate" their original reusability model is given. To validate the proposal, the strategy is instantiated to the dom ain of mathematical software. By referring to the calibrated reusability mo del, we carried out a large scale empirical investigation in order to selec t candidate reusable stand-alone (FORTRAN) routines from two commercial lib raries belonging to the mathematical domain totally adding up to 2500 routi nes. The second part of the paper reports about such an experiment. (C) 200 0 Elsevier Science Inc. All rights reserved.