OOPSLA'05 CLOS tutorial
- OOPSLA'05 tutorial on generic functions and the CLOS Metaobject Protocol
Town and Country Resort & Convention Center, San Diego, California
Sunday, October 16, 2005, 13:30 - 17:00
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.