An approach to software evolution based on semantic change

Abstract. The analysis of the evolution of software systems is a useful source of information for a variety of activities, such as reverse engineering, maintenance, and predicting the future evolution of these systems. Current software evolution research is mainly based on the information contained in versioning systems such as CVS and SubVersion. But the evolutionary information contained therein is incomplete and of low quality, hence limiting the scope of evolution research. It is incomplete because the historical information is only recorded at the explicit request of the developers (a commit in the classical checkin/checkout model). It is of low quality because the file-based nature of versioning systems leads to a view of software as being a set of files. In this paper we present a novel approach to software evolution analysis which is based on the recording of all semantic changes performed on a system, such as refactorings. We describe our approach in detail, and demonstrate how it can be used to perform fine-grained software evolution analysis.