Modular object-oriented programming with units and mixins

Module and class systems have evolved to meet the demand for reuseable soft ware components. Considerable effort has been invested in developing new mo dule and class systems, and in demonstrating how each promotes code reuse. However, relatively Little has been said about the interaction of these con structs, and how using modules and classes together can improve programs. I n this paper, we demonstrate the synergy of a particular form of modules an d classes-called units and mixins, respectively-for solving complex reuse p roblems in a natural manner.