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Subject: Re: Recreational Common Lisp  :)
From: Mark Conrad <nos...@iam.invalid>
Newsgroups: comp.lang.lisp
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Date: Thu, 08 May 2003 03:17:08 GMT
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In article <87el3apd5y....@darkstar.cartan>, Nils Goesche
<n...@cartan.de> wrote:

> ...lotsa interesting stuff...

I could not locate the example I was looking for about 
define-symbol-macro  breaking, so I whiped up another example quickly.
It is not as good an example because I get a compiler 'warning' in this
case, but it will get across the idea.

Example #1 with eval-when
*********************************************
Welcome to the demo version of Macintosh Common Lisp Version 4.3!

? (define-symbol-macro %cont%  #'identity)
%CONT%


? (eval-when (:load-toplevel :execute)
  (setf (symbol-value '%cont%)
        (lambda (&rest args)
          (if (cdr args)
              args
              (car args)))))
#<Anonymous Function #x1EFB84DE>


? (define-symbol-macro k 'meow)
K


? (let ((r  %cont%))
     (defun test () (print(funcall %cont%  'woof))  (setq r 'bow-wow) r
)  )
;Compiler warnings :
;   Undeclared free variable %CONT%, in an anonymous lambda form.
TEST



? (test)
WOOF
BOW-WOW


? (funcall %cont% k)
MEOW
? 
*******************************************


Example #2  without eval-when
#################################
Welcome to the demo version of Macintosh Common Lisp Version 4.3!

? (define-symbol-macro %cont%  #'identity)
%CONT%


? (define-symbol-macro k 'meow)
K
  


? (let ((r  %cont%))
     (defun test () (print(funcall %cont%  'woof))  (setq r 'bow-wow) r
)  )

;Compiler warnings :
;   Undeclared free variable %CONT%, in an anonymous lambda form.
> Error: Unbound variable: %CONT%
> While executing: #<Anonymous Function #x1EF2B69E>
> Type Command-/ to continue, Command-. to abort.
> If continued: Retry getting the value of %CONT%.
See the RestartsŠ menu item for further choices.
1 > 
#################################

Mark-