Refactoring delta-oriented software product lines

Abstract

Delta-oriented programming (DOP) is an implementation approach to develop software product lines (SPL). Delta-oriented SPLs evolve over time due to new or changed requirements and need to be maintained to retain their value. Refactorings have been proposed as behavior-preserving program transformations that improve the design and structure of (object-oriented) software systems. However, there is a lack of refactoring support for software product lines since refactoring of SPLs is more complex than of single systems. For refactoring SPLs, we have to preserve the behavior of probably thousands of programs instead of only one. In this paper, we address the refactoring of software product lines by presenting a catalogue of refactorings for delta-oriented SPLs. Additionally, we propose code smells to guide developers to potential refactoring opportunities. We show how code smells can aid the identification of SPL refactorings and how these refactorings improve the evolvability and maintainability of delta-oriented SPLs.