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From: barmar@mit-eddie.UUCP (Barry Margolin)
Newsgroups: net.lang.lisp
Subject: Re: Responses to: "LISP" by Winston & Horn: is the 2nd Edition better?
Message-ID: <4384@mit-eddie.UUCP>
Date: Mon, 3-Jun-85 03:39:46 EDT
Article-I.D.: mit-eddi.4384
Posted: Mon Jun  3 03:39:46 1985
Date-Received: Tue, 4-Jun-85 00:51:38 EDT
References: <2433@wateng.UUCP>
Reply-To: barmar@mit-eddie.UUCP (Barry Margolin)
Distribution: net
Organization: MIT, Cambridge, MA
Lines: 31

In article <2433@wateng.UUCP> ksbszabo@wateng.UUCP (Kevin Szabo) writes:
>For example when they discuss property lists they mention how to get
>values off the plist (with get) but they do not mention the function to
>put properties on the property list (put).  Instead they use a macro
>(setf) which is used to set other things as well.
>
>wisc-ai!neves (David Neves)
Common Lisp doesn't have a "put" or "putprop" function.  The only way to
put items on the property list in Common Lisp is with "setf".  These
functions were probably not included so that the CL designers didn't
have to decide between the various incompatible argument orders that
were used by the corresponding functions in the dialects that were being
coalesced into CL.

If you want a Maclisp-style putprop, it is an easy function to define
given the CL facilities:

(defun putprop (symbol value indicator)
  (setf (get symbol indicator) value))

By the way, I don't think "setf" is a macro in CL (it is a macro in
Maclisp and Zetalisp).  If it were, then there would have to be a "put"
or "putprop" for it to expand into in the above use.  But for many
structures, such as property lists and arrays, "setf" is the only setter
defined by the language, so it has to be a special form.  Unfortunately,
I'm not at my office (where my copy of Steele's CL book is) right now,
so I can't check this out for sure.
-- 
    Barry Margolin
    ARPA: barmar@MIT-Multics
    UUCP: ..!genrad!mit-eddie!barmar