Combining active rules and metaclasses for enhanced extensibility in object-oriented systems

This paper is concerned with techniques for supporting extensibility in object-oriented data models. It has been recognised for a number of years that, in systems which support metaclasses as first-class objects, extensibility can be achieved by using specialisation to refine built-in object creation behaviour. At the same time, research into active rules has indicated the utility of mapping high-level descriptions of functionality onto active rules for evaluation. This paper proposes the integration of these two techniques, arguing that certain constructs which would be difficult to represent using either one alone can be supported effectively by a judicious mixing of the two. © 1993.