Refactoring for Reuse: An Empirical Study

TL;DR

This study empirically investigates how developers refactor code to enhance reusability, analyzing 1,828 open-source projects to understand the types and impacts of reusability-focused refactorings.

Contribution

It provides the first large-scale empirical analysis of reusability refactorings, highlighting differences from mainstream refactoring practices and their effects on high-level code elements.

Findings

Reusability refactorings differ from mainstream refactorings in type distribution.

Reusability refactorings target high-level code elements like packages, classes, and methods.

These refactorings significantly impact design-level aspects of the code.

Abstract

Refactoring is the de-facto practice to optimize software health. While several studies propose refactoring strategies to optimize software design through applying design patterns and removing design defects, little is known about how developers actually refactor their code to improve its reuse. Therefore, we extract, from 1,828 open-source projects, a set of refactorings that were intended to improve the software reusability. We analyze the impact of reusability refactorings on the state-of-the-art reusability metrics, and we compare the distribution of reusability refactoring types, with the distribution of the remaining mainstream refactorings. Overall, we found that the distribution of refactoring types, applied in the context of reusability, is different from the distribution of refactoring types in mainstream development. In the refactorings performed to improve reusability, source files are subject to more design-level types of refactorings. Reusability refactorings significantly impact, high-level code elements, such as packages, classes, and methods, while typical refactorings, impact all code elements, including identifiers, and parameters. These findings provide practical insights into the current practice of refactoring in the context of code reuse involving the act of refactoring.