PORK Object System Programmers' Guide - The Robotics Institute Carnegie Mellon University
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PORK Object System Programmers’ Guide

Ora Lassila
Tech. Report, CMU-RI-TR-95-12, Robotics Institute, Carnegie Mellon University, April, 1995
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PORK is an object system which brings a conventional object-oriented language closer to the requirements of frame-based programming. It only provides a very limited set of features (on top of the base object system itself), and aims to achieve seamless integration with conventional programming. PORK is implemented as a portable metalevel extension of the Common Lisp Object System (CLOS). It extends CLOS by adding the following concepts: * Named objects. These simplify debugging and linked frame model construction. Collections of named objects (called "namespaces") can also be used as a low-level implementation vehicle for knowledge bases. * References to nonexisting named objects. Programs can manipulate objects that have not yet been created. This greatly simplifies definition of complex linked frame models with circular references. * Slots with multiple values, and a mechanism for defining an access interface. * Automatic updating of inverse slots.


author = {Ora Lassila},
title = {PORK Object System Programmers’ Guide},
year = {1995},
month = {April},
institution = {Carnegie Mellon University},
address = {Pittsburgh, PA},
number = {CMU-RI-TR-95-12},

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