Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!wiley!scott
From: scott@wiley.uucp (Scott Simpson)
Newsgroups: comp.lang.lisp
Subject: Using Packages With CLOS
Keywords: packages, information hiding, CLOS classes, file naming conventions
Message-ID: <26B09E74.58E0@wilbur.coyote.trw.com>
Date: 27 Jul 90 20:05:07 GMT
Sender: news@wilbur.coyote.trw.com (News Software)
Organization: TRW Inc., Redondo Beach, CA
Lines: 20

How do people use packages with CLOS classes? The most obvious
solution to me would be to make a separate package for each class. My
office mate objected to this, saying that it would cause problems with
inheritance. He noted that symbols are local to a package and when you
inherit from another class you would need to know the superclasses
name to access any inherited slot. My retort was that you should
provide accessor functions for superclass slots in your class and
export them if you wish to enable the user of the class to access an
inherited slot. Then if you changed the superclass for any reason the
code behind the package wall would change but the accessor function
used by the user using the class would not change.
	Another issue is the mapping between file names and CLOS
classes. Do you normally create a different file for each CLOS class?
This seems to me to be simple method for quickly identifying where
classes are stored. If all the files are stored in the same directory,
it regrettably flattens the type hierarchy structure you are trying to
simulate but I think it is the best you can do without some sort of
object-oriented database underneath.
Scott Simpson    		TRW 			scott@coyote.trw.com
Scott Simpson    		TRW 			scott@coyote.trw.com