Expression and Composition of Design Patterns with AspectJ

Abstract : Design patterns are well-known couples of problems-solutions for software engineer- ing. By nature, they often lack support from languages and this further complicates the study of their composition in the code. Aspect-oriented languages provide new mechanisms for modula- rization, which can help to improve design patterns implementation. (Hannemann et al., 2002) is the first extensive study of patterns aspectization with AspectJ. We notice some AspectJ idioms are needed in order to implement object relationships. We give a more reusable VISITOR pat- tern. We highlight a reusable composition of COMPOSITE and VISITOR patterns and expressive interactions of the OBSERVER pattern with a tree structure. We thus show that modularization by aspects helps composition of design patterns.