From: Barry Fishman <barry_fishman@att.net>
Subject: Re: elisp macros problem
Date: Tue, 27 Jul 2004 23:22:42 GMT [thread overview]
Message-ID: <m3hdrtyr2a.fsf@ecube.site> (raw)
In-Reply-To: x5zn5lvs43.fsf@lola.goethe.zz
David Kastrup <dak@gnu.org> writes:
> Lowell Kirsh <lkirsh@cs.ubc.ca> writes:
>
>> This still doesn't seem to work. With the following defun and call:
>>
>> (defmacro my-add-hooks (hooks &rest body)
>> `(dolist (hook ',hooks)
>> (my-add-hook hook ,@body)))
>>
>> (my-add-hooks (inferior-lisp lisp emacs-lisp lisp-interaction)
>> (imenu-add-to-menubar "Symbols"))
>>
>> > you hoping to achieve that you would not be better off doing by a
>> > proper function instead of a macro?
>
> In short, I still consider this sort of thing a crock, since you'd be
> better off using a function instead of a macro. You are unable to
> comprehend what your macros do, and it shows. Macros are just not
> sensible for this sort of thing. Use functions instead. You'll need
> to use some quotes at the outer level, but you'll understand what
> happens.
>
> To fix the above, you'd need to write something like
>
> (defmacro my-add-hooks (hooks &rest body)
> (dolist (hook hooks)
> `(my-add-hook ,hook ,@body)))
The body of the defmacro has to return some code. The dolist
will return just NIL.
Assuming that you want my-add-hooks to create a series of my-add-hook
calls, one would need something like:
(defmacro my-add-hooks (hooks &rest body)
(cons 'progn (mapcar (lambda (h) `(my-add-hook ,h ,@body)) hooks)))
Its usually easier to do the work in a function and use a macro to
create the syntax you want. For example, using a function like:
(defun my-add-hooks-fn (hooks func)
(dolist (hook hooks)
(add-hook (intern (concat (symbol-name hook) "-mode-hook")) func)))
One can give it the syntax you want with a macro like:
(defmacro my-add-hooks (hooks &rest body)
`(my-add-hooks-2 ',hooks (lambda () ,@body)))
This has the advantage of creating a single lambda function rather
than multiple lambda functions with the same contents.
This also allows one to build a more complex my-add-hooks-fn without
dealing with the extra complexity of structuring it as a macro.
--
Barry Fishman
prev parent reply other threads:[~2004-07-27 23:22 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-24 18:39 elisp macros problem Lowell Kirsh
2004-07-24 19:00 ` David Kastrup
2004-07-24 22:08 ` Lowell Kirsh
2004-07-24 23:41 ` David Kastrup
2004-07-25 1:58 ` Lowell Kirsh
2004-07-25 10:59 ` Kalle Olavi Niemitalo
2004-07-24 19:15 ` Barry Margolin
2004-07-24 19:59 ` Pascal Bourguignon
2004-07-24 20:50 ` David Kastrup
2004-07-24 21:49 ` Lowell Kirsh
2004-07-26 1:35 ` Lowell Kirsh
2004-07-26 1:55 ` Rahul Jain
2004-07-26 2:53 ` Lowell Kirsh
2004-07-26 4:05 ` Pascal Bourguignon
2004-07-26 4:13 ` Lowell Kirsh
2004-07-26 2:54 ` Lowell Kirsh
2004-07-26 22:16 ` Kalle Olavi Niemitalo
2004-07-26 22:58 ` Kevin Rodgers
2004-07-26 2:03 ` Barry Margolin
2004-07-26 3:06 ` Lowell Kirsh
2004-07-26 4:49 ` Barry Margolin
2004-07-26 5:20 ` Pascal Bourguignon
2004-07-26 6:10 ` Oliver Scholz
2004-07-26 5:55 ` David Kastrup
2004-07-27 6:38 ` Lowell Kirsh
2004-07-27 6:54 ` Lowell Kirsh
2004-07-27 7:14 ` David Kastrup
2004-07-27 8:10 ` Lowell Kirsh
2004-07-27 12:05 ` Pascal Bourguignon
2004-07-28 5:03 ` Rob Warnock
2004-07-31 20:46 ` Lowell Kirsh
2004-08-03 18:44 ` Michael Slass
2004-07-27 23:22 ` Barry Fishman [this message]
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