Computational reflection in class based object oriented languages

Abstract

This paper describes various models of computational reflection in class based object oriented language. Two different approaches are covered: the meta-object approach which supposes that every object can have a meta-object describing and monitoring its behavior, and the message reification approach which describes a message as an object. The meta-object approach is discussed more fully showing that it is important to differenciate between structural reflection and computational reflection. We will see that, whereas classes and metaclasses are very important for the former, they cannot cope adequately with the later. Therefore we introduce a model of computational reflection where meta-objects are instances of a class META-OBJECT or of one of its subclasses.