Refactoring and Reflection

Tuesday, 28 October – 10:30-12:00

Language-Independent Aspect-Oriented Programming

Donal Lafferty, Trinity College Dublin, Donal.Lafferty@cs.tcd.ie
Vinny Cahill, Trinity College Dublin, Vinny.Cahill@cs.tcd.ie

The term aspect-oriented programming (AOP) has come to describe the set of programming mechanisms developed specifically to express crosscutting concerns. Since crosscutting concerns cannot be properly modularized within object-oriented programming (OOP), they are expressed as aspects and are composed, or woven, with traditionally encapsulated functionality referred to as components.

Many AOP models exist, but their implementations are typically coupled with a single language. To allow weaving of existing components with aspects written in the language of choice, AOP requires a language-independent tool.

This paper presents Weave.NET, a load-time weaver that allows aspects and components to be written in a variety of languages and freely intermixed. Weave.NET relies on XML to specify aspect bindings and ECMA Common Language Infrastructure to avoid coupling aspects or components with a particular language.

By demonstrating language-independence, Weave.NET provides a migration path to the AOP paradigm by preserving existing developer knowledge, tools and software components. The tool's capabilities are demonstrated with logging aspects written with and applied to Visual Basic and C# components.

Refactoring for Generalization Using Type Constraints

Frank Tip, IBM T.J. Watson Research Center, tip@watson.ibm.com
Adam Kiezun, IBM Research OTI Labs, adam_kiezun@ch.ibm.com
Dirk Baeumer, IBM Research OTI Labs, dirk_baeumer@ch.ibm.com

Refactoring is the process of applying behavior-preserving transformations (called "refactorings") in order to improve a program's design. Associated with a refactoring is a set of preconditions that must be satisfied to guarantee that program behavior is preserved, and a set of source code modifications. An important category of refactorings is concerned with generalization (e.g., "Extract Interface" for re-routing the access to a class via a newly created interface, and "Pull Up Members" for moving members into a superclass). For these refactorings, both the preconditions and the set of allowable source code modifications depend on interprocedural relationships between types of variables. We present an approach in which type constraints are used to verify the preconditions and to determine the allowable source code modifications for a number of generalization-related refactorings. This work is implemented in the standard distribution of Eclipse (see www.eclipse.org).

Partial Behavioral Reflection: Spatial and Temporal Selection of Reification

Eric Tanter, University of Chile, École des Mines de Nantes/INRIA, Eric.Tanter@emn.fr
Jacques Noyé, École des Mines de Nantes/INRIA, Jacques.Noye@emn.fr
Denis Caromel, Université de Nice, Denis.Caromel@inria.fr
Pierre Cointe, École des Mines de Nantes/INRIA, Pierre.Cointe@emn.fr

Behavioral reflection is a powerful approach for adapting the behavior of running applications. In this paper we present and motivate partial behavioral reflection, an approach to more efficient and flexible behavioral reflection. We expose the spatial and temporal dimensions of such reflection. In the context of Java, we present a reflective architecture offering appropriate interfaces for static and dynamic configuration of partial behavioral reflection at various levels, as well as an open reflective extension for Java implementing this architecture. Reflex is the first extension that fully supports partial behavioral reflection in a portable manner, and that seamlessly integrates load-time and runtime behavioral reflection, along with static optimizations. The paper shows preliminary benchmarks and examples supporting the approach. The examples, dealing with the observer pattern and asynchronous communication via transparent futures, also show the interest of partial behavioral reflection as a tool for open dynamic aspect-oriented programming.