Object Specialization

[wtwolfe@hubcap.clemson.edu (Bill Wolfe)]

  An interesting paper entitled "Object Specialization" appears in
  ACM Transactions on Information Systems, April 1989, pages 103-122;
  it combines the efficiency of class-based systems with the flexibility
  of prototype-based systems, and provides an elegant solution to the 
  problem of "intersection classes" which eliminates the need for (and
  the desirability of) multiple inheritance.  Additionally, it provides
  an elegant way to model different perspectives on (or implementations
  of) a single real-world entity -- for example, a person's address might
  differ depending on whether that person is viewed as a consumer (home 
  address) or as a worker (business address).  

  This paper has led me to modify my previous position that multiple
  inheritance should be incorporated into Ada 9X; single inheritance
  via specialization at the object level appears to be a fundamentally 
  better solution, capable even of representing semantic constraints
  which cannot be represented by traditional class-based approaches.

  The power, flexibility, and efficiency of this new approach should 
  be very seriously evaluated during the design of Ada 9X's improved 
  support for the process of object-oriented software construction.


  Bill Wolfe, wtwolfe@hubcap.clemson.edu