Julien Cohen

Akram Ajouli, Julien Cohen, Jean-Claude Royer

Basic automated refactoring operations can be chained to perform complex structure transformations. This is useful for recovering the initial architecture of a source code which has been degenerated with successive evolutions during its maintenance lifetime. This is also useful for changing the structure of a program so that a maintenance task at hand becomes modular when it would be initially crosscutting. We focus on programs structured according to Composite and Visitor design patterns, which have dual properties with respect to modularity. We consider a refactoring-based round-trip transformation between these two structures and we study how that transformation is impacted by four variations in the implementation of these patterns. We validate that study by computing the smallest preconditions for the resulting transformations. We also automate the transformation and apply it to JHotDraw, where the studied variations occur.

Julien Cohen, Rémi Douence, Akram Ajouli

When one chooses a main axis of structural decompostion for a software, such as function- or data-oriented decompositions, the other axes become secondary, which can be harmful when one of these secondary axes becomes of main importance. This is called the tyranny of the dominant decomposition. In the context of modular extension, this problem is known as the Expression Problem and has found many solutions, but few solutions have been proposed in a larger context of modular maintenance. We solve the tyranny of the dominant decomposition in maintenance with invertible program transformations. We illustrate this on the typical Expression Problem example. We also report our experiments with Java and Haskell programs and discuss the open problems with our approach.