Issues in the Design of an . . .

The object oriented paradigm, which advocates bottom-up program development, appears at first sight to run counter to the classical, top-down approach of structured programming. The deep requirement of structured programming, however, is that programming should be based on well-defined abstractions with clear meaning rather than on incidental characteristics of computing machinery. This requirement can be met by object oriented programming and, in fact, object oriented programs may have better structure than programs obtained by functional decomposition. The definitions of the basic components of object oriented programming, object, class, and inheritance, are still sufficiently fluid to provide many choices for the designer of an object oriented language. Full support of objects in a typed language requires a number of features, including classes, inheritance, genericity, renaming, and redefinition. Although each of these features is simple in itself, interactions between features can..