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Re: How does one use a macro in a special form?
From: |
Alan Mackenzie |
Subject: |
Re: How does one use a macro in a special form? |
Date: |
Sat, 28 Jun 2003 18:17:36 +0000 |
User-agent: |
tin/1.4.5-20010409 ("One More Nightmare") (UNIX) (Linux/2.0.35 (i686)) |
Daniel Jensen <daniel-news@bigwalter.net> wrote on Sat, 28 Jun 2003
20:00:48 +0200:
> Alan Mackenzie<none@example.invalid> writes:
>> In particular, I want to use a macro acm-indent++ within a let (or let*),
> You can't. Let is a special form and does not follow conventional
> evaluation rules.
>> The macro acm-indent++ looks like this:
>>
>> (defmacro acm-indent++ ()
>> "Increase the level of indentation in an acm-printf output by binding
>> indent-spaces.
>> This form must appear \"comma\"d in a let/let* variable list."
>> `(indent-spaces (concat indent-spaces " ")))
> Use something like this instead:
> (defmacro with-extra-indent-spaces (&rest body)
> `(let ((indent-spaces (concat indent-spaces " ")))
> ,@body))
> (let (...)
> (with-extra-indent-spaces
> ...))
>> Question: does the "," operator have meaning when not within a
>> backquote expression?
> No. Then it's just a character. It is only an "operator" inside
> backquoted forms.
Many thanks for the chrystal clear answers. I think for this thing, I'll
just write out the indent-spaces thing in longhand each time I need it.
> Daniel Jensen
--
Alan Mackenzie (Munich, Germany)
Email: aacm@muuc.dee; to decode, wherever there is a repeated letter
(like "aa"), remove half of them (leaving, say, "a").