Extensible organization of property descriptions in object modelling for engineering design

Abstract

Object-oriented information systems capturing engineering-design property information run into a problem of extensibility. While class hierarchies defining generic engineering information may be developed according to a classification based on science and general-purpose engineering, this leaves aside special-purpose properties such as those inspired by a particular type of artefact. These properties may be the deciding factor in a particular design application of the data system; thus the ability to 'add in' property descriptions specified for a specialist view of a design function within an enterprise often determines the practical usefulness of the object model adopted. Partitioned classes are proposed as a modelling mechanism which addresses the need for 'upward customization' of generic knowledge. The solution allows the extension of any class to be partitioned between general- and special-purpose members. Advantages of this scheme over multiple inheritance are demonstrated using relational analysis, and they are illustrated by its implementation within an information retrieval system for the visual display of property data.