An Empirical Study on Clone Evolution by Analyzing Clone Lifetime

Abstract

The existence of code clones has several negative impacts on software maintenance which is why vast amount of research exists in the literature to characterize clone evolution. Most of those focused on clone genealogy, and clone changeness (consistent and inconsistent changes). However, analyzing clone evolution with respect to clone location and clone lifetime requires more attention to better characterize clone evolution. In this research, an empirical study has been performed on clone evolution by considering clone location (i.e., Inter-File and Intra-File) and clone lifetime. The study has been performed on four open source software covering 12 to 66 number of versions. In the study, it has been found that, (i) Intra-File clones occurred in a repository more than Inter-File clones, which infers that developers tend to clone code in the same file than different files and (ii) Intra-File clones are more volatile than Inter-File clones, which infers that developers like to refactor or change clones of the same file more than clones spanning different files. These observations help to conclude which clones should get more attention during clone maintenance tasks like refactoring.