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This paper describes a new technique for organizing software which has been used successfully by the Xerox Star 8010 workstation. The workstation (WS) software is written in an “object-oriented” style: it can be viewed as a system of inter-communicating objects of different object types. Most of the WS software considers object types to be constructed by assembling more primitive abstractions called traits. A trait is a characteristic of an object, and is expressed as a set of operations which may be applied to objects carrying that trait. The traits model of subclassing generalizes the SIMULA-67 model by permitting multiple inheritance paths. This paper describes the relationship of WS software to the traits model and then describes the model itself.
Curry et al. (Fri,) studied this question.