A user interface/view editor for a VLSI CAD database in an object-oriented framework called Cbase is described. The interface provides a platform for invoking and integrating diverse tools besides providing graphic capability for editing various views of the circuit. The object-oriented nature of Cbase leads to an adaptive and customizable user interface. The most important aspect of the user interface is its extensibility. New object types can be added to the system type hierarchy with practically no change to the user interface code. This is accomplished through judicious use of polymorphism and metainformation to avoid hard coding in the program. Another question addressed is whether or not a persistent data structure can support an interactive application such as a user interface. Performance figures for some typical user interface operations are presented. These figures reveal that the performance, though quite satisfactory for small-to-medium-size systems, may require close attention to object caching, clustering, and storage management for large circuits.
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