The contribution of this paper are speculations on emerging software engineering approaches that promote evolution and reuse. These speculations are, however, based on extensive experience in the area of building software tools, i.e., tools that analyze, transform, or generate software.
The plan for the paper is as follows. In Section 2, we sketch a new approach to building software that we are currently applying in various projects. In Section 3, we describe case studies that illustrate our approach. In Section 4, we draw some general conclusions for the field of software engineering as a whole and point at several research directions.
Managerial and economic aspects of reuse--and of software engineering in general--are of utmost importance (Lim, 1994) but we will largely ignore them. The only exception is Section 4.4 where we discuss usage-based pricing methods for software in relation to the evolutionary software engineering that we propose in this paper. Basili et al. (1992) give an organizational view on component factories that can be used as complement to the technical view presented by us.