On Object-Oriented Extensions Of Information Hiding

Abstract

The criterion of information-hiding wu originally developed for a otinctured approach in design. The advent of object-oriented design methodology and languages potentially allows the designer to implement information-hiding more effectively. In reality, however, building a program as a set of cooperating objects often results in a web of dependencies that makes an object-oriented program even more difficult to maintain than a traditional program. Two extensions of the concept of information-hiding are proposed: shared knowledge among object types and visibility of object types to other types. The first extension concentrates on the division of responsibilities among objects of different types. This form of information-hiding is related to the traditional concept of cohesion. The seccnd extension helps to organise object communications when an object of one type sends to an object of another type a message with an object of the third type as a parameter. This form of information-hiding is related to the criterion of coupling in traditional design. At a case study, a prototype model of an inventory control system written in C++ is discussed. Alternative design are compared. The use of proposed extensions is shown to be effective in elimination unnecessary complexity of design.