From: Chip Salzenberg
Subject: Free variables: special or global?
Date: Tue, 14 Nov 1989 18:07:50 +0000
Message-ID: <25605478.27727@ateng.com>

I've been reading and re-reading the relevant sections in CLtL, and I've
been unable to answer this question.

Consider this code:

	(defvar *parrot* "live")            ; Global value: "live"

	(defun cleese ()
	  (let ((*parrot* "dead"))
	    (declare (special *parrot*))    ; Dynamic value: "dead"
	    (palin)))

	(defun palin ()
	  (print *parrot*))                 ; Which will I see??

	(cleese)                            ; What will be printed?

When (cleese) calls (palin), the global value of *parrot* is "live" and the
most recent dynamic value is "dead".  Which is printed?  And where in CLtL
is this question answered?

I know that if I really want the dynamic value, I can write:

	(defun palin ()
	  (locally (special *parrot*)
	    (print *parrot*)))

But is the "locally special" necessary, even in the absence of any lexical
bindings?  And if it isn't necessary, how can I access the _global_ value
("dead")?

E-Mail or post as you like.  I'll summarize mail to the net.
-- 
You may redistribute this article only to those who may freely do likewise.
Chip Salzenberg at A T Engineering;  <····@ateng.com> or <uunet!ateng!chip>