Extraction and improvement of conditionally compiled product line code

Conditional Compilation (CC) is one of the most widely used variation mechanisms in the development of software product lines (SPLs). However, a problem in SPL maintenance is that conditionally compiled code blocks are often overly scattered, nested, and tangled, which makes the code difficult to understand. Moreover, if variant code is evolved independently of the corresponding variability model, there is a risk that the two may become inconsistent. As a countermeasure, this paper proposes a maintenance process, consisting of variability extraction, error detection, and refactoring, to improve the quality of product line implementation.