AN OBJECT-ORIENTED MODEL OF DESIGN EVOLUTION

The paper presents a general model of design evolution, intended to be shared by all forms of digital circuit CAD data subject to change. This provides a common view of design evolution, based on immutable design states. This view simplifies concurrent access control and consistency maintenance. Object-oriented inheritance is used to specialise the general model for particular forms of information, which may need their histories managed in different ways. Two examples are described; one is based on differential representations of successive states and is suited to managing evolution in an editor environment, and the other is appropriate for managing untracked changes in an automatically generated design.