CLOSe to the edge? Advanced object-oriented techniques in the representation of musical knowledge

Abstract The modeling of knowledge about musical expression asks for quite some flexibility during the design process and for the availability of high‐level abstractions to represent successfully the complex concepts and their interactions in this domain. One would expect, because of the enthusiastic claims made in the literature on object‐oriented programming, that such an approach would be ideal for this task. This paper describes some aspects of the Common Lisp Object System (CLOS), a modern object‐oriented language that indeed provides some advanced constructs that proved useful in the design and maintenance of a complex system for the manipulation of expression in music. However, some of the mechanisms should be used with care to stay far from the point beyond which programs become too complex to grasp.