Complex and Composite Objects in CAD/CAM Databases
An essential modelling concept for CAD/CAM databases is the composition relationship which relates a superior composite object to its components and makes the component's data visible in the composite object. In order to import only the necessary information into the composite object, often an interface object is defined which is copied into the composite object as an abstraction of the component. In this paper an object oriented model is introduced which comprises an inheritance relationship between an inheritor object and a transmitter object. The inheritor object inherits (the existence of) attributes of the transmitter object, but moreover it also may inherit the attributes' values. This inheritance relationship can be used to model the notion of interface of an object as well as the composition relationship. Thus, by using the only concept of value inheritance it is possible to model all aspects of the composition of objects. Furthermore, some severe drawbacks of a rigid interface concept can be overcome by the inheritance relationship.
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