Path: utzoo!utgpu!watserv1!watmath!att!rutgers!usc!wuarchive!uunet!mcsun!ukc!edcastle!aiai!jeff
From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Newsgroups: comp.lang.lisp
Subject: Re: Common Lisp Package System Considered Harmful
Keywords: Object-Oriented Programming, CLOS, packages, information hiding
Message-ID: <3589@skye.ed.ac.uk>
Date: 19 Oct 90 17:11:12 GMT
References: <271BA6D1.5B83@wilbur.coyote.trw.com> <2298@heavens-gate.lucid.com> <271CDC30.1E54@wilbur.coyote.trw.com>
Reply-To: jeff@aiai.UUCP (Jeff Dalton)
Organization: AIAI, University of Edinburgh, Scotland
Lines: 22

In article <271CDC30.1E54@wilbur.coyote.trw.com> scott@wiley.UUCP (Scott Simpson) writes:

>And if I have multiple classes within one package then I have
>information hiding problems.

Use a package for a "service" (ie, something that "clients" might
use).  Such facilities might involve several classes that logically
go together.  (That is, it makes sense to make them be part of the
same service)  A CLOS implementation would be one example.  It
contains a number of classes, but will involve only one (or a few)
package(s).

The information-hiding problems among different classes in the
same poackage, when the package embodies a reasonable, logical
grouping, are not serious enough to worry about -- at least not 
in Common Lisp.   If you worry about them, then you will find
that packages don't work very well for you.

If you expect packages to give you the same capabilities you
have in Eiffel or Ada, you are bound to be disappointed.  

-- Jeff