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Keywords in make-instance?
- To: firstname.lastname@example.org
- Subject: Keywords in make-instance?
- From: Jon L White <email@example.com>
- Date: Sat, 4 Jun 88 01:13:36 PDT
- Cc: Bobrow.pa@Xerox.COM, Timothy.Freeman@proof.ergo.cs.cmu.edu, commonloops.pa@Xerox.COM
- In-reply-to: Rob Pettengill's message of Thu, 2 Jun 88 16:59:48 CDT <8806022159.AA20155@perseus.sw.mcc.com>
- Redistributed: commonloops.pa
re: Common Lisp does not specify that a keyword argument MUST come from the
keyword package. They only do so by default. The keyword arguments
for make-instance obey thi same rule.
This was my interpretation as well. However, CLtL, does not
explicitly say that the &key keyword can come from any package. At
least one vendor, (Lucid 2.04), restricts function lambda list &key
keywords to being in the keyword package.
Danny is wrong here, as is your intuition too. See the first sentence
on CLtL p62, which requires keyword parameter names to be "keywords"
(i.e., symbols in the keyword package). There is even a "rationale"
proffered for this decision. [This certainly is an easy one to overlook,
since 1988 hindsight has so many advantages over 1983 foresight.]
Lucid obeys the letter-of-the-law from CLtL, but has given full support
to the X3J13 Cleanup Committee's proposal entitled
which relaxes the CLtL constraint. In fact, one of the motivating forces
behind this proposal is so that CLOS methods aren't limited to having
&key arguments named only in the "flat" namespace of package KEYWORD.
[There is a reason why such a limitation is much more troublesome when
using defmethod than when using defun or defmacro, but I'll not take time
to go into it now.]
Lucid release 2.1 and later doesn't seem to impose the constraint in
compiled functions; I don't know about release 2.04. It is Lucid's intent
to conform to the X3J13 proposal as soon as practical after its adoption.
-- JonL --