Re: Function CCL::STRUCTURE-SLOT-NAMES undefined.

[bill@cambridge.apple.com (Bill St. Clair)]

>Date: Fri, 23 Oct 92 05:07:35 PDT
>From: rem@public.btr.com (Robert E. Maas  rem@btr.com)
>To: bill@cambridge.apple.com
>Subject: Re: Function CCL::STRUCTURE-SLOT-NAMES undefined.
>
>> To: frege@crim.eecs.umich.edu
>> Cc: info-mcl@cambridge.apple.com
>> Date: Wed, 12 Aug 1992 13:48:37 -0500
>(I fell behind in my browsing interest groups and answering some
>questions and replying to a few other messages, but now (Oct.22-23
>about midnight) I finally found time to read this posting of yours that
>I downloaded several weeks ago, and I'm writing this reply ...)
>
>Previous poster said <<When apropos'd STRUCTURE-SLOT-NAMES exists in
>COMMON-LISP-USER package. However, I can't use it in MCL 2.0. How do I
>access the function?>> and you replied <<There is no such symbol in MCL
>2.0. Did you perhaps inadvertently intern it yourself by passing it to
>APROPOS? It is best to always pass strings, not symbols to APROPOS:>>
>
>There should be some way that system packages can be write-protected,
>so that if you try to INTERN anything into them that is not already
>there an error is signalled. Is that mechanism available in any version
>of MCL or is it proposed in future versions?

I have never heard this idea before. It sounds reasonable.
Maybe it could be controlled by *warn-if-redefine-kernel* and signal
a continuable error, just as DEFUN does when one attempts to redefine
a kernel function. One drawback is that lots of the example files
intern symbols in the CCL package. Opinions?