Oh, that eieio. There's another one:

    Description: Enhanced Implementation of Emacs Interpreted Objects
    EIEIO is an Emacs lisp program which implements a controlled
    object-oriented programming methodology following the CLOS
    standard. EIEIO also has object browsing functions, and custom widget
    types. It has a fairly complete manual describing how to use it.
 
    EIEIO is now a part of CEDET (Collection of Emacs Development
    Environment Tools).