Search-based refactoring: Metrics are not enough

Abstract

Search-based Software Engineering (SBSE) techniques have been applied extensively to refactor software, often based on metrics that describe the object-oriented structure of an application. Recent work shows that in some cases applying popular SBSE tools to open-source software does not necessarily lead to an improved version of the software as assessed by some subjective criteria. Through a survey of professionals, we investigate the relationship between popular SBSE refactoring metrics and the subjective opinions of software engineers. We find little or no correlation between the two. Through qualitative analysis, we find that a simple static view of software is insufficient to assess software quality, and that software quality is dependent on factors that are not amenable to measurement via metrics. We recommend that future SBSE refactoring research should incorporate information about the dynamic behaviour of software, and conclude that a human-in-the-loop approach may be the only way to refactor software in a manner helpful to an engineer.