Augmentation of object-oriented programming by concepts of abstract data type theory: the ModPascal experience

Object-oriented programming and abstract data type (ADT) theory have emerged from the same origin of computer science: the inability to deal efficiently with 'programming in the large' during the early seventies. Each of the approaches has led to significant practical and theoretical results resp. Nevertheless it is still unsatisfactory that up to now the mutual influence seems to be limited to more or less syntactical issues (e.g. the provision of packages, clusters, forms). In this paper we report on the object-oriented language ModPascal that was developed as part of the Integrated Software Development and Verification (ISDV) Project. We show how the essence of concepts of ADT theory as algebraic specifications, enrichments, parameterized specifications or signature morphisms as well as their semantics can be consistently integrated in an imperative object-oriented language. Furthermore, as the experience of using ModPascal as target language of the ISDV System has shown, we claim that without similar support of theoretical concepts techniques like formal specification of programs or algebraic verification loose their power and even applicability.