Microsoft Word OpenIssuesInOO. doc

versus prototype-based languages; and concurrency. 

The point of views presented in this paper reflects the authors background in the Scandinavian 

tradition as manifested in the BETA language and the Mjølner project. 

KEY WORDS  Languages, object-orientation, modeling, reuse, conceptual framework, abstraction 

mechanisms, class-based languages, prototype-based languages, concurrency. 

1. Introduction 

Although the history of object-oriented programming goes back more then 30 years to the 

development of the Simula languages, there are still a number of issues that may be 

considered open, in the sense that there is no consensus about them in the object-oriented 

programming community. Open is a relative term here: there are issues where everybody 

agrees, some where most people agree, and some where there is a lot of disagreement. There 

is also a difference in what is considered open in the research community and what is con-

sidered open among practitioners.  

The point of view presented in this paper reflects the author's background in the 

Scandinavian tradition of object-oriented programming. This tradition started with the de-

velopment of the Simula languages in the early sixties by Ole-Johan Dahl and Kristen 

Nygaard. Simula was originally developed as a simulation language (Simula I [DN66]), but 

it was soon realised that the principles behind Simula I could be used for programming in 

general, leading to the development of Simula 67 [DNM68]. An account of  the history of 

Simula may be found in Reference [DN81] and an introduction to Simula may be found in 

Reference [Mag94a].  The BETA language [KMMN83a, MMN93] has been developed in