OOPSLA'05 tutorial on generic functions and the CLOS Metaobject Protocol
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Town and Country Resort & Convention Center, San Diego, California
Sunday, October 16, 2005, 13:30 - 17:00
See http://p-cos.net/oopsla05-tutorial.html
Abstract.
The Common Lisp Object System (CLOS) is unique in two ways.
+ In most OOP languages, methods belong to classes and are invoked by
sending messages. In CLOS, methods belong to generic functions instead
of classes, and those generic functions select and execute the correct
method according to the types of the arguments they receive.
+ The CLOS Metaobject Protocol (MOP) specifies how its essential
building blocks are to be implemented in CLOS itself. This allows
extending its object model with metaclasses that change important
aspects of CLOS for a well-defined scope.
This tutorial introduces these two notions. I will develop - live during
the tutorial - the code for an interpreter for generic functions that
performs selection and execution of methods. I will then discuss how
that code can be extended to introduce, for example, multimethods and
AOP-style advices, and sketch how generic functions are implemented
efficiently in the "real" world. In the second part, I will illustrate
the extensibility of the CLOS MOP by implementing - live - the
(hashtable-based) Python object model as a metaclass. Other practical
extensions based on the CLOS MOP are also sketched, like
object-relational mappings, interfaces to foreign-language objects, and
domain-specific annotations in classes.
The audience will learn about the basic concepts of generic functions
and metaobject protocols. They will get the necessary insights and
pointers to existing literature and online material to deepen their
knowledge. The focus of the tutorial is not on technical details but on
the general ideas. A good understanding of class-based OOP is required.
Experience with Lisp may be helpful, but the tutorial is specifically
targeted at non-Lispers.
Feel free to contact me if you have any questions and/or suggestions.
Pascal