Ecoop 95 Object Oriented Programming

ECOOP '95 - Object-Oriented Programming

For the ninth time now, the European Conference on Object-Oriented P- gramming provides a mid-summer gathering place for researchers, practitioners, students and newcomers in the field of object technology. Despite fierce c- petition from an increasing number of attractive conferences on object-related topics, ECOOP has successfully positioned itself as the premier European - ject technology conference. One reason is without doubt the composition of the conference week and the nature of its events. Running in parallel on the first two days, a comprehensive tutorial program and a very selective workshop program are offered to attendees. This is followed by a three-day technical p- gram organized in a single track providing a highly communicative atmosphere of scientific exchange and learning. Overlapping with these events are a two-day industrial exhibition and a two-day opportunity for non-industrial system dev- opers to demonstrate their software. Thus, ECOOP is not just a conference on programming but an event touching on the full spectrum of object technology. This volume constitutes the proceedings of the Ninth European Conference on Object-Oriented Programming, ECOOP, held in Aarhus, Denmark, August 7-11, 1995. Previous ECOOP conferences were held in Paris (France), Oslo (Norway), Nottingham (England), Ottawa (Canada, jointly with OOPSLA) , Geneva (Switzerland), Utrecht (the Netherlands) , Kaiserslautern (Germany) , and Bologna (Italy). Object technology continues to increase its impact on the corporate world.

ECOOP '95

Object-Oriented Programming A Unified Foundation

by Luea Cardelli Ever since Strachey's work in the 1960's, polymorphism has been classified into the parametric and overloading varieties. Parametric polymorphism has been the subject of extensive study for over two decades. Overloading, on the other hand, has often been considered too ad hoc to deserve much attention even though it has been, in some form, an ingredient of virtually every programming lan guage (much more so than parametric polymorphism). With the introduction of object-oriented languages, and in particular with multiple-dispatch object-oriented languages, overloading has become less of a programming convenience and more of a fundamental feature in need of proper explanation. This book provides a compelling framework for the study of run-time over loading and of its interactions with subtyping and with parametric polymorphism. The book also describes applications to object-oriented programming. This new framework is motivated by the relatively recent spread of programming languages that are entirely based on run-time overloading; this fact probably explains why this subject was not investigated earlier. Once properly understood, overloading reveals itself relevant also to the study of older and more conventional (single dispatch) object-oriented languages, clarifying delicate issues of covariance and contravariance of method types, and of run-time type analysis. In the final chapters, a synthesis is made between parametric and overloading polymorphism.