Re: Strange behavior of macro

["Herbert Euler" <herberteuler@hotmail.com>]

>From: Andreas Schwab <schwab@suse.de>
>To: "Herbert Euler" <herberteuler@hotmail.com>
>CC: emacs-devel@gnu.org
>Subject: Re: Strange behavior of macro
>Date: Tue, 30 May 2006 12:23:49 +0200
>
>"Herbert Euler" <herberteuler@hotmail.com> writes:
>
> > Is the following in Emacs a expected behavior of macro?
> >
> >    (defmacro m1 (v)
> >      (let ((len (length (eval v))))
> >        `(quote ,len)))
> >         => m1
>[...]
> >    (m1 v)
> >         => error: (wrong-type-argument sequencep v)
>
>See (elisp)Eval During Expansion.

OK, so it's an accepted behavior.  Btw, in the test of GNU clisp,
it's safe to write such a macro:

[1]> (defmacro m1 (v)
       (let ((len (length (eval v))))
         `(quote ,len)))
M1
[2]> (m1 '(1 2 3))
3
[3]> (setq v1 '(1 2 3))
(1 2 3)
[4]> (m1 v1)
3
[5]> (setq v v1)
(1 2 3)
[6]> (m1 v)
3
[7]>

Regards,
Guanpeng Xu

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