Experiments towards a general implementation of some design patterns using aspect orientation

Abstract

This dissertation presents a novel technique to implement the behaviour of some widely used design patterns using a combination of aspect oriented programming and computational reflection.

Object-oriented languages do not support design patterns as a language construct, instead these have to be specifically implemented by the programmer. As a result, their implementation ends up scattered over different classes and tangled with the domain code of such classes, leading to reusability, modularity and comprehensibility issues.

The aspect-oriented implementations presented in this thesis get rid of such issues. A design pattern is implemented as an aspect which, by intercepting an annotation that marks an application class, enforces the role of the pattern on that class, thus making the pattern available for the system.

Such implementations enjoy four properties, especially defined from from the analysis of the literature, considered useful and not found together in existing approaches.

Efficient variants of the proposed approach are also described and compared with the standard object-oriented approach in terms of running times.

The proposed implementations can be used in object-oriented legacy applications, applying specific refactoring steps to convert legacy code to make it use the aspect versions.