🚀 go-pugleaf

nicholas writes

    
How can I add a slot to a class? One solution is to redefine class but that
isn't terribly portable since it requires having the source definition
of the class. P. 203 of the AMOP describes how a slot instance can be
created, e.g., (make-instance  'clos:standard-slot-definition ...).
Then, the question becomes how can a slot instance be added to a given class
as if it were (almost) a re-definition of the class? Can this be done
in a portable manner? If not, I'd be equally interested in an
implementation-specific solution for Lucid 4.0.2 on sparc.

I recently faced the same problem, and at first my solution was to
maintain protability and implement my own metainfo class.  This class
had attributes that managed class name, slot names, etc and had methods
for redefining a class given a prototype instance using eval and quotes
that did not require any calls to metaobject protocol methods.

I have since reimplemented this  to use MOP methods because:

	Much of it is available in Lucid 4.02 (on DEC)
	Implementation became cleaner because clos was managing
                   the metainformation so I didn't have to - my code was not
                    robust or general enough to do the job very well
              MOP seems to be becomming standardized 
                     (this I say only as an outsider looking in - it may or may
                        not be true, but it is my observation)


If you want to see any code examples, I can send them, but I