An object-oriented medical decision support system

The `Histology System´ (H.A. Heathfield 1990) is a decision support system intended to assist pathologists in the histological diagnosis of breast disease. It is intended as a research vehicle to explore the potential role of computer-assisted diagnosis in pathology. It was implemented in the object-oriented language C++ (B. Stroustrup 1986). The system exhibits components which can be easily replaced or changed, or used in new applications. It would seem that a system constructed around objects rather than around procedures automatically reduces the coupling between components. However, there were problems. For example, inheritance was not of much benefit in the Histology System, due to lack of guidance and experience with it. This meant that code reuse at the object level was not fully exploited. A theory of inheritance would have provided an easier and safer way to exploit the benefits of inheritance than trial and error. The authors maintain that formalised theories offer the programmer the mental structures necessary to think about design, which can usually only be gained by experience. Object-oriented technology is often claimed to support a `natural´ approach to software development-the authors´ experience is that this is a misleading claim, although the technical benefits are real enough