Active Oberon for .NET: An Exercise in Object Model Mapping

Abstract

Active Oberon is a substantial evolution of the programming language Oberon. It distinguishes itself by a novel object model and by its integration into the .NET language interoperability framework.The three concepts characterizing Active Oberon are: (a) active object types, (b) a single and unifying notion of abstraction called definition, and (c) a static module construct. These concepts are in fact powerful combinations of concepts: Active objects integrate active behavior with reactive message handling, definitions unify the units of usage, implementation and inheritance, and modules represent both package and static object. The rigid concept of class hierarchy has been sacrificed in Active Oberon to a more flexible concept of aggregation that is based on a generalized IMPLEMENTS relation. The relations IMPORTS and REFINES are used to specify static module dependencies and to derive new definitions from existing ones respectively.This article is a report on a work in progress. We divide our presentation into three parts: (a) A short recall of the history of programming languages developed at the ETH, (b) an extensive conceptual overview of Active Oberon's object model called the Active Object System (AOS), (c) a discussion of the mapping of the AOS into the Common Type System (CTS) exposed by .NET.