Levi's Lisp Log

Context-Oriented Lisp

Thanks to the extensive metaprogramming facilities in Common Lisp, it is often used as an experimental testbed for new programming paradigms. Recently, Pascal Costanza and Robert Hirschfeld have come up with a new form of program structuring called Context-Oriented Programming.

Roughly, the idea is to create different "layers" in the software that expose different portions of objects' interfaces. This allows for changes in behavior based on context rather than just the traditional mechanisms of subtyping and composition. I'd explain further myself, but Bill Clementson has created a tutorial based on the example in Costanza and Hirschfeld's paper that does a better job than I could.

If you'd like to try it out, the ContextL extension to Common Lisp can be found at the Closer Project site, along with additional information about ContextL and Common Lisp's Meta-Object Protocol, which made ContextL possible.