Towards a catalog of composite refactorings

Abstract

Catalogs of refactoring have key importance in software maintenance and evolution, since developers rely on such documents to understand and perform refactoring operations. Furthermore, these catalogs constitute a reference guide for communication between practitioners since they standardize a common refactoring vocabulary. Fowler's book describes the most popular catalog of refactorings, which documents single and well‐known refactoring operations. However, sometimes, refactorings are composite transformations, that is, a sequence of refactorings is performed over a given program element. For example, a sequence of Extract Method operations (a single refactoring) can be performed over the same method, in one or in multiple commits, to simplify its implementation, therefore, leading to a Method Decomposition operation (a composite refactoring). In this paper, we propose and document a catalog with eight composite refactorings. We also implement a set of scripts to mine composite refactorings by preprocessing the results of refactoring detection tools. Using such scripts, we search for composites in a representative refactoring oracle with hundreds of confirmed single refactoring operations. Next, to complement this first study, we also search for composites in the full history of 10 well‐known open‐source projects. We characterize the detected composite refactorings, under dimensions such as size and location. We conclude by addressing the applications and implications of the proposed catalog.

Method level static source code analysis on behavioral change impact analysis in software regression testing

“…Recent research shows a significant increase into the development of automated tools for static source code analysis like FindBugs [3] and extract method feature [19]. Both extract method refactoring and composite method refactoring [20] tools, help improve program understandability and comprehension supported by an empirical study on the characteristics of method extractions in Java [21].…”

On the Completeness of Composite Code Refactorings for Beneficial Smell Remova

“…Researchers have investigated approaches to contribute to refactoring applications for many years [251]. Recent studies indicated limitations regarding existing knowledge about refactoring, and cataloged composites that can fully remove code smells [77,171,227]. Catalogs are useful to guide developers (e.g., to effectively remove smells) and tool builders (e.g., to build tools that recommend effective refactorings).…”

“…However, the existing catalogs are not aligned with the current software development practices and have certain limitations [77,171,227]. The first limitation of existing catalogs is that their recommendations are not well-detailed.…”

“…Despite indicating side effects, the authors have not performed an in-depth empirical analysis of side effects for complete composites. Another example can be found in the catalog of Brito et al [227], where there is a recommendation for using Pull Up Methods to create a single and more general method in the superclass, leveraging code reuse. However, Brito et al do not alert developers about the side effects of those Pull Up Methods.…”

“…The second limitation concerns the insufficient description about the side effects of existing recommendations. For instance, Brito et al [227] Pull Up Methods to create a single and more general method in the superclass, achieving code reuse. However, they do not alert developers about the side effects of Pull Up Methods in practice.…”