PCLOS: Stress Testing CLOS Experiencing the Metaobject Protocol

Abstract

This paper demonstrates that the CLOS metaobject protocol approach to defining and implementing an object model is very powerful. CLOS is an object-oriented language that is based on Common Lisp and is in the process of being standardized. Implementations of CLOS are themselves object-oriented with all major building blocks of the language being instances of system classes. A metaobject protocol provides a framework for CLOS implementations by specifying the hierarchy of these classes and the order and contents of the communication among their instances. This design has made CLOS both flexible and portable, two design goals that traditionally conflict. In support of this suggestion we present a detailed account of how we added object persistence to CLOS without modifying any of the language's implementation code.