Differences between Oberon and Oberon-2

Oberon–2 is a true extension of Oberon [1]. This paper summarizes the extensions and tries to shed some light on the motivations behind them. By that we hope to make it easier for the reader to classify Oberon–2. For details the reader is referred to the language report. One important goal for Oberon–2 was to make object–oriented programming easier without sacrificing the conceptual simplicity of Oberon. After three years of using Oberon and its experimental offspring Object Oberon [2] we merged our experiences into a single refined version of Oberon. The new features of Oberon–2 are type–bound procedures, read–only export of variables and record fields, open arrays as pointer base types, and a with statement with variants. The for statement is reintroduced after having been eliminated in the step from Modula–2 to Oberon. Oberon–2 is the result of many discussions among all members of the Institute for Computer Systems at ETH. It is particularly influenced by the ideas of Jürg Gutknecht and Josef Templ.