SOFTWARE—PRACTICE AND EXPERIENCE Softw. Pract. Exper. 2008; 38:361–396 Published online 21 August 2007 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/spe.835 An illustrative example of refactoring object-oriented source code with aspect-oriented mechanisms Miguel P. Monteiro 1 and Jo˜ ao M. Fernandes 2, ∗, † 1 Departamento de Inform´ atica, Faculdade de Ciˆ encias e Tecnologia da Universidade Nova de Lisboa, 2829-516 Caparica, Portugal 2 Departamento de Inform´ atica & CCTC, Universidade do Minho, 4710-057 Braga, Portugal SUMMARY This paper describes a refactoring process that transforms a Java source code base into a functionally equivalent AspectJ source code base. The process illustrates the use of a collection of refactorings for aspect-oriented source code, covering the extraction of scattered implementation elements to aspects, the internal reorganization of the extracted aspects and the extraction of commonalities to super-aspects. Copyright © 2007 John Wiley & Sons, Ltd. Received 12 May 2006; Revised 29 April 2007; Accepted 1 May 2007 KEY WORDS: refactoring; aspect-oriented programming; design patterns 1. INTRODUCTION Refactoring [1] and aspect-oriented programming (AOP) [2] are two techniques that contribute to deal with the problems of continuous evolution of software. This paper shows how both techniques can be combined to improve the structure of an existing system. In doing so, it also illustrates current notions of good style for AOP. ∗ Correspondence to: Jo˜ ao M. Fernandes, Departamento de Inform´ atica, Universidade do Minho, 4710-057 Braga, Portugal. † E-mail: jmf@di.uminho.pt Contract/grant sponsor: FCT Contract/grant sponsor: FEDER; contract/grant number: POSC/EIA/60189/2004 Copyright 2007 John Wiley & Sons, Ltd.