Language-technical aspects of reuse

Reuse happens only when a variety of social conditions are favorable. However, social conditions, development processes, and design methods alone cannot guarantee success. In the end, working code must be produced, and at this stage programming languages and programming styles can make a critical difference. The paper focuses on C++ and its use because that´s where the author´s experience is, and because reuse in the abstract is a sterile exercise. To yield its obvious benefits, reuse must be practised. Reuse is a result of good design; it is not something you get from simple minded use of special language features. The paper presents examples of how designs of components for use in several contexts can be expressed directly and efficiently in C++. Concrete types, abstract classes, class hierarchies, and generic programming using templates are mentioned.