On the difficulties of raising the level of abstraction and facilitating reuse in software modelling: the case for signature extension.

Reuse is central to improving the software development process, increasing software quality and decreasing time-to-market. Hence it is of paramount importance that modelling languages provide features that enable the specification and modularization of reusable artefacts, as well as their subsequent reuse. In this paper we outline several difficulties caused by the finality of method signatures that make it hard to specify and use reusable artefacts encapsulating several variants. The difficulties are illustrated with a running example. To evaluate whether these difficulties can be observed at the programming level, we report on an empirical study conducted on the Java Platform API as well as present workarounds used in various programming languages to deal with the rigid nature of signatures. Finally, we outline signature extension as an approach to overcome these problems at the modelling level.