Multiple-type objects in an enhanced C plus plus persistent programming language

An entity in the real world may obtain and lose its roles, or aspects, agai n and again with time. For modeling such dynamic changes of aspects, object s having multiple types, or multiple-type objects, are essential to persist ent programming languages. In this paper, we introduce multiple-type object s, and show a method of implementing them in an enhanced C++ persistent pro gramming language called INADA, Any persistent objects in INADA may obtain any type at any time the type is needed, and may lose any unnecessary types dynamically. We also present a performance study in which the performance penalty caused by the introduction of multiple-type objects was examined, C opyright (C) 2000 John Wiley & Sons, Ltd.