Issues in Performing and Automating the “Extract Method Calls” Refactoring

A large part of converting a pre-AOP application into an aspect-oriented one consists, next to aspect mining, out of aspect refactoring. One such aspect refactoring named “Extract Method Calls” refactoring [11, 17] transforms certain crosscutting concerns which are implemented by calls to a single method into an aspect by turning the called method into an advice and all the calls to that method into a crosscut. In this paper we present the Joinpoint Choice Problem and the Flattened Expression Problem. Both problems are inherent to the joinpoint models as used by current-day weavers and can have a negative impact on the maintainability and evolvability of the crosscuts resulting from performing the “Extract Method Calls” refactoring either by hand or automatically. As a solution to the Joinpoint Choice Problem, we propose an algorithm for calculating the appropriate crosscut. In order to solve the Flattened Expression Problem, we introduce a new language construct named the “statement joinpoint”. In section 2 we describe the “Extract Method Calls” refactoring. Section 3 we present the Joinpoint Choice Problem and Flattened Expression Problem. We discuss solutions for these problems in section 4. After presenting some related work and research directions for the future (section 5),