From: Alan Mackenzie <acm@muc.de>
To: David Kastrup <dak@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: Idempotency of add-hook wrt lambda expressions
Date: Thu, 5 Mar 2009 16:38:53 +0000 [thread overview]
Message-ID: <20090305163853.GB1855@muc.de> (raw)
In-Reply-To: <861vtcxpt1.fsf@lola.quinscape.zz>
On Thu, Mar 05, 2009 at 10:49:14AM +0100, David Kastrup wrote:
> Geoff Gole <geoffgole@gmail.com> writes:
> >> I'd much rather add a patch that complains when you pass a lambda to
> > add-hook.
> > Sounds good to me.
> Does not jibe with existing practise.
"Me too!".
> For example, (info "(emacs) Init Examples") carefully explains
> * Turn on Auto Fill mode automatically in Text mode and related
> modes.
> (add-hook 'text-mode-hook
> '(lambda () (auto-fill-mode 1)))
> This shows how to add a hook function to a normal hook variable
> (*note Hooks::). The function we supply is a list starting with
> `lambda', with a single-quote in front of it to make it a list
> constant rather than an expression.
> It's beyond the scope of this manual to explain Lisp functions,
> but for this example it is enough to know that the effect is to
> execute `(auto-fill-mode 1)' when Text mode is entered. You can
> replace that with any other expression that you like, or with
> several expressions in a row.
> Sure, you can "fix" the manual here. But you can't expect that the
> real world has never used an idiom explicitly documented and used as an
> example.
I have stuff like the following in my setup:
(global-set-key [f1] (lambda () "Switch to frame F1"
(interactive)
(select-frame-acm-no 0)))
That `global-set-key' might easily have been an `add-hook'. I think it
would get tedious very quickly if warnings were given with add-hook +
lambda. To outlaw it would be the Wrong Thing completely.
With all due respect to Geoff, I don't think this is really a problem.
> Also, in some cases you can't avoid lambda, namely when using computed
> functions.
Yes.
> David Kastrup
--
Alan Mackenzie (Nuremberg, Germany).
next prev parent reply other threads:[~2009-03-05 16:38 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-04 12:10 Idempotency of add-hook wrt lambda expressions Geoff Gole
2009-03-04 14:18 ` Stefan Monnier
2009-03-04 20:13 ` xah lee
2009-03-04 21:23 ` Stefan Monnier
2009-03-04 21:27 ` Lennart Borgman
2009-03-05 17:22 ` M Jared Finder
2009-03-04 21:00 ` David Reitter
2009-03-05 1:27 ` Stephen J. Turnbull
2009-03-05 1:54 ` Stefan Monnier
2009-03-05 8:23 ` Geoff Gole
2009-03-05 9:49 ` David Kastrup
2009-03-05 11:41 ` tomas
2009-03-05 11:53 ` Geoff Gole
2009-03-05 16:45 ` Alan Mackenzie
2009-03-05 16:33 ` Helmut Eller
2009-03-05 16:38 ` Stefan Monnier
2009-03-05 16:50 ` Geoff Gole
2009-03-05 16:38 ` Alan Mackenzie [this message]
2009-03-05 20:44 ` Reiner Steib
2009-03-05 20:59 ` Edward O'Connor
2009-03-05 21:08 ` Reiner Steib
2009-03-06 9:36 ` David Kastrup
2009-03-05 16:12 ` Alan Mackenzie
2009-03-05 16:37 ` Stefan Monnier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20090305163853.GB1855@muc.de \
--to=acm@muc.de \
--cc=dak@gnu.org \
--cc=emacs-devel@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).