KELLY@Rutgers@sri-unix (12/07/82)
I have been following the smalltalk "object-orientedness" discussion on INFO-MICRO for the past week or so, and was wondering if any of the participants have read any of the papers on the ORBIT system, a true "object-oriented" system (multiple inheritance of both properties and procedures, etc.) without a "message passing" system model. The basis for ORBIT is an underlying SCHEME-like language which uses the lexical scoping of both function and variable names, together with function closures, to implement both encapsulation and inheritance. The result is a language of great economy (i.e. small and fast) which looks like LISP and behaves (much) like SMALLTALK. It also inherits most of the theoretical elegance of SCHEME and its cousins. The technical papers describing ORBIT are available from the AI group at Schlumberger-Doll Research in Ridgefield, Ct. The most accessible seem to be: Steels, Luc (1981) "Programming with objects using ORBIT". AI Memo 13 Steels, Luc (1982) "An Applicative View of Object-Oriented Programming". AI Memo 15 I am certainly not proposing ORBIT as a be-all and end-all programming system. My first-hand experience with object-oriented systems is limited to UNITS (a message-passing system) and GLISP (a slightly less elegant applicative system than ORBIT, built on top of a non-SCHEME-like LISP), so I certainly cannot claim to be a wizard in such matters. But if theoretical cleanness is worth much, to say nothing of code clarity, then I would have to give ORBIT's approach my vote for the best flavor I have seen so far in object-oriented languages, SMALLTALK included. Van E. Kelly KELLY@RUTGERS -------