Ole-Johan Dahl

Ole-Johan Dahl (12 October 1931 – 29 June 2002) was a Norwegian computer scientist. Dahl was a professor of computer science at the University of Oslo and is considered to be one of the fathers of Simula and object-oriented programming along with Kristen Nygaard. In 2001, Dahl and Nygaard won the ACM Turing Award.

Career Dahl was born in Mandal, Norway. He was the son of Finn Dahl (1898–1962) and Ingrid Othilie Kathinka Pedersen (1905–80). When he was seven, his family moved to Drammen. When he was thirteen, the whole family fled to Sweden during the German occupation of Norway in World War II. After the war's end, Dahl studied numerical mathematics at the University of Oslo.

Dahl is widely accepted as Norway's foremost computer scientist. With Kristen Nygaard, he produced the initial ideas for object-oriented (OO) programming in the 1960s at the Norwegian Computing Center (Norsk Regnesentral (NR)) as part of the Simula I (1961–1965) and Simula 67 (1965–1968) simulation programming languages, which began as an extended variant and superset of ALGOL 60. Dahl and Nygaard were the first to develop the concepts of class, subclass (allowing implicit information hiding), inheritance, dynamic object creation, etc., all important aspects of the OO paradigm. An object is a self-contained component (with a data structure and associated procedures or methods) in a software system. These are combined to form a complete system. The object-oriented approach is now pervasive in modern software development, including widely used imperative programming languages such as C++ and Java.

He received the Turing Award for his work in 2001 (with Kristen Nygaard). He received the 2002 Institute of Electrical and Electronics Engineers (IEEE) John von Neumann Medal (with Kristen Nygaard) and was named Commander of the Royal Norwegian Order of St. Olav in 2000.

The Association Internationale pour les Technologies Objets named the Dahl-Nygaard Prize after Dahl.

Early papers

Organized by IFIP Technical Committee 2, programming languages; O.-J. Dahl, conference chairman.