Unifying Theories of Objects

Abstract

We present an approach to modelling Abadi–Cardelli-style object calculi as UTP designs. Here we provide a core object calculus with an operational small-step evaluation rule semantics, and a corresponding UTP model with a denotational relational predicate semantics. For clarity, the UTP model is defined in terms of an operand stack, which is used to store the results of subprograms. Models of a less operational nature are briefly discussed. The consistency of the UTP model is demonstrated by a structural induction proof over the operations of the core object calculus. Overall, our UTP model is intended to provide facilities for encoding both object-based and class-based languages.