International Conference on Logic Programming edition:20 location:Saint-Malo, France date:Septemer 6-10, 2004
Refactoring is an established technique from the OO-community to
restructure code: it aims at improving software readability, maintainability
and extensibility. Although refactoring is not tied to the OO-paradigm in
particular, its ideas have not been applied to Logic Programming until now.
This paper applies the ideas of refactoring to Prolog programs. A catalogue
is presented listing refactorings classified according to scope. Some of
the refactorings have been adapted from the OO-paradigm, while others have been
specifically designed for Prolog. Also the discrepancy between intended
and operational semantics in Prolog is addressed by some of the refactorings.
In addition, ViPReSS, a semi-automatic refactoring browser,
is discussed and the experience with applying ViPReSS to a large Prolog
legacy system is reported. Our main conclusion is that refactoring is not only
a viable technique in Prolog but also a rather desirable one.