GNU bug report logs - #15296
24.3.50; A macro object does not necessarily have `lambda' as its cadr

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Drew Adams <drew.adams <at> oracle.com>
Subject: bug#15296: closed (Re: bug#15296: 24.3.50; A macro object does
 not necessarily have `lambda' as its cadr)
Date: Sun, 08 Sep 2013 18:03:02 +0000

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Your bug report

#15296: 24.3.50; A macro object does not necessarily have `lambda' as its cadr

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 15296 <at> debbugs.gnu.org.

-- 
15296: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=15296
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Drew Adams <drew.adams <at> oracle.com>
Cc: 15296-done <at> debbugs.gnu.org
Subject: Re: bug#15296: 24.3.50;
 A macro object does not necessarily have `lambda' as its cadr
Date: Sun, 08 Sep 2013 14:01:53 -0400

> `macro' and whose `cdr' is a lambda expression.  That's not true if the

I changed it to say "function" instead.


        Stefan

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From: Drew Adams <drew.adams <at> oracle.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.3.50; A macro object does not necessarily have `lambda' as its cadr
Date: Fri, 6 Sep 2013 22:39:58 -0700 (PDT)

AFAICT, (elisp) `Defining Macros' is the closest thing we have to doc
telling you how to test whether a Lisp object is a macro.  There is no
`macro-p' predicate or similar in Emacs Lisp, unless I'm missing
something.  (Shouldn't there be?)

Anyway, this Elisp manual node says that a macro is a list whose car is
`macro' and whose `cdr' is a lambda expression.  That's not true if the
`defmacro' was byte-compiled.  The macro is then a list whose car is `macro'
but whose cdr is byte code, AFAICT.  So this will not work, for example:

(defun macro-p (obj)
  (and (fboundp obj)
       (let ((def  (symbol-function obj)))
         (and (consp def)
              (eq (car def) 'macro)
              (eq (cadr def) 'lambda)))))

In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2013-08-23 on ODIEONE
Bzr revision: 113986 rgm <at> gnu.org-20130823185841-zoy6h1qk433ibrlf
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/binary --enable-checking=yes,glyphs
 'CFLAGS=-O0 -g3' LDFLAGS=-Lc:/Devel/emacs/lib
 CPPFLAGS=-Ic:/Devel/emacs/include'

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