Synchronizing Software Variants: a Two-Dimensional Approach.

Code copying and customization is a common practice to realize variability and serve the demand for custom-tailored software. The clone-and-own-approach is flexible and efficient, but does not scale with the number of variants as developers must transfer changes between clones manually, which is an error-prone and tedious task. This task becomes even more challenging, when developers reuse code not only between variants, but also within variants. As a solution, we propose a novel synchronization technique that supports developers to transfer changes applied to clones to its corresponding clone instances within a variant as well as across other variants. Our technique relies on a common model of clone relationships between and within variants, that can automatically propagate changes two-dimensional into the respective intra- and inter-clone instances. In an empirical evaluation, we demonstrate the need for this two-dimensional clone synchronization and show the usefulness and scalability of our approach using the MobileMedia case study.