From: "José A. Romero L." <escherdragon@gmail.com>
To: help-gnu-emacs@gnu.org
Subject: Re: How to put this in a macro
Date: Sat, 17 Apr 2010 03:30:04 -0700 (PDT) [thread overview]
Message-ID: <bf0039f9-f7eb-497d-bb74-88d3bb9c5077@u34g2000yqu.googlegroups.com> (raw)
In-Reply-To: 87d3xywpm6.fsf@linux-lqcw.site
On 17 Kwi, 08:38, Cecil Westerhof <Ce...@decebal.nl> wrote:
> Barry Margolin <bar...@alum.mit.edu> writes:
> > (defmacro canonicalize-start-end (start-var end-var)
> > `(if (equal ,start-var ,end-var)
> > (setq ,start-var (point-min)
> > ,end-var (point-max))
> > (setq ,start-var (or ,start-var (point-min))
> > ,end-var (or ,end-var (point-max))))
>
> This gives an error:
> Debugger entered--Lisp error: (void-variable start-var)
> (list (quote equal) start-var end-var)
(...)
Makes sense. In general writing things like `(setq ,foo bar) is (if
possible at all) asking for trouble -- what would happen when foo is
nil, or 5?
Maybe you could do something like this:
(defmacro cw/set-bounds (start-sym end-sym)
`(if (equal (symbol-value ,start-sym) (symbol-value ,end-sym))
(progn
(set ,start-sym (point-min))
(set ,end-sym (point-max)))
(progn
(set ,start-sym (or start (point-min)))
(set ,end-sym (or end (point-max))))))
and use it as:
(cw/set-bounds 'start 'end)
i.e. passing the symbols of the variables you want to set.
Cheers,
--
José A. Romero L.
escherdragon at gmail
"We who cut mere stones must always be envisioning cathedrals."
(Quarry worker's creed)
next prev parent reply other threads:[~2010-04-17 10:30 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-16 21:13 How to put this in a macro Cecil Westerhof
2010-04-16 23:28 ` José A. Romero L.
2010-04-17 3:08 ` Barry Margolin
2010-04-17 6:38 ` Cecil Westerhof
2010-04-17 10:30 ` José A. Romero L. [this message]
2010-04-17 11:07 ` Cecil Westerhof
2010-04-17 11:40 ` Cecil Westerhof
2010-04-17 15:15 ` José A. Romero L.
2010-04-17 16:49 ` Barry Margolin
2010-04-17 16:57 ` José A. Romero L.
2010-04-17 21:41 ` Barry Margolin
2010-04-17 19:38 ` Cecil Westerhof
2010-04-17 23:58 ` José A. Romero L.
2010-04-17 12:13 ` José A. Romero L.
2010-04-17 15:14 ` Barry Margolin
2010-04-17 16:49 ` José A. Romero L.
2010-04-17 15:12 ` Barry Margolin
2010-04-18 7:50 ` Pascal J. Bourguignon
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