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Re: type slot option
This seems to be the most problematic of the criticisms we received.
Looking over all the mail, it seems that the best thing to do is to
leave the :type option the way it is. It might be good to add a note
making it extra clear that because of the way it is defined it cannot
be used as a semantic feature. It might also be good to clarify this
section by alluding to defstruct.
It seems clear that in our presentation to X3J13 we should point out to
them that this is a problematic issue which we `inherited' from Common
Lisp in general and defstruct in particular.
Date: Fri, 29 Apr 88 14:15 PDT
- leave things the way they are, but make it clear that it
is the job of the user code to enforce the type option.
You're right that :TYPE is a compiler optimization, not a semantic
feature. It's like the TYPE declaration in that respect. If slot
options had been defined in a syntactically consistent way (i.e.
enclosed in parentheses like class options) then the syntax of this
slot option could have been based on the syntax of DECLARE and just
possibly people would be less confused about what it means. I'm not
seriously proposing that; I'd rather eliminate the option, if we're
going to make such a large change.
Date: Sat, 30 Apr 88 01:52:48 PDT
From: Jon L White <email@example.com>
Perhaps a reasonable way out of the situation is to "defer" it to CL's
treatment of the :type option in defstruct. If ever there is mandated
such a "mode" as I referred to for defstruct, then CLOS could follow the
Date: Mon, 2 May 88 09:38:04 CDT
From: Patrick H Dussud <DUSSUD@Jenner.csc.ti.com>
I think this issue is too big to be decided in this group. I wouldn't
take decision before asking the whole X3J13. In case it produces an
endless and intractable discussion, I would be in favor of turning off
this option until a concensus emerges.
Date: Mon, 02 May 88 08:41:29 -0700
I don't think we should eliminate the :type option, but I think we
ought to make it work exactly like the defstruct :type option on
pg. 310 of CLtL.
Date: 30 Apr 88 10:19 PDT
From: Dick Gabriel <RPG@SAIL.Stanford.EDU>
As you all recall, my original writeup of this option stated that
attempting to store an invalid type SHOULD signal an error. Moon objected
on the grounds that he did not want to have to ever check it, except when
other operations would naturally check the contents (such as during an
Thus, I never saw this as a compiler pragma only but as a semantic issue.
I would favor a redux to my original wording (yes, ``redux'' is the word I