. 1 It is a common wisdom of component technology that reuse is not obtained automatically: one has to design for reuse; and reusability has to be preserved as a key quality through design, implementation and maintenance. Besides other technologies aiming at reuse, the component based approach gains increasing attention. Although the idea of reusing prefabricated software components is not new, many obstacles hinder reuse and make it hard to achieve the benets of reuse in practice. In general few components are reused as they are. Often, available components are incompatible with what is required. This necessitates extensions or adaptations. In this paper we develop a method assisting the software engineer in identifying the detailed causes for incompatibility and systematically overcoming them. Our method also permits the synthesis of common adapters, coercing incompatible components into meeting requirements. 1 Introduction It is a common wisdom of component technol...

Sub would implement method Foo through a method with a signature matching that of Foo: PROCEDURE (this:Sub) Foo*(), NEW; END Foo; As an alternative, Sub may "explicitly" implement method Foo by using the following syntax: PROCEDURE (this:Sub.Interface) Foo*(), NEW; END Foo; This concept of "explicit" method implementation is the same as that used in C# [8]. Explicit implementation removes the method from the namespace of the class, thus preventing the method from being called except through an interface reference. This allows for the implementation of several versions of the same interface in one class.

Since the early 1990’s, component-based software technology has become an increasingly popular approach to facilitate the development of evolving systems as it promised to address some of the problems of object-oriented development technologies. By reconfiguring components, adapting existing components, or introducing new components it was hoped that applications could be adapted to changing requirements more easily than using traditional approaches. But has component-based software technology succeeded? Have we been able to address the problems identified more than a decade ago? Which problems still need further investigations? In this work, we will review some of the goals component-based development was supposed to achieve, investigate whether these goals have been met, and propose a research agenda of topics for further investigation. 1