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Re: Idempotency of add-hook wrt lambda expressions
From: |
Alan Mackenzie |
Subject: |
Re: Idempotency of add-hook wrt lambda expressions |
Date: |
Thu, 5 Mar 2009 16:38:53 +0000 |
User-agent: |
Mutt/1.5.9i |
On Thu, Mar 05, 2009 at 10:49:14AM +0100, David Kastrup wrote:
> Geoff Gole <address@hidden> 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).
- Re: Idempotency of add-hook wrt lambda expressions, (continued)
- Re: Idempotency of add-hook wrt lambda expressions, Stephen J. Turnbull, 2009/03/04
- Re: Idempotency of add-hook wrt lambda expressions, Stefan Monnier, 2009/03/04
- Re: Idempotency of add-hook wrt lambda expressions, Geoff Gole, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions, David Kastrup, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions, tomas, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions, Geoff Gole, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions, Alan Mackenzie, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions, Helmut Eller, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions, Stefan Monnier, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions, Geoff Gole, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions,
Alan Mackenzie <=
- Re: Idempotency of add-hook wrt lambda expressions, Reiner Steib, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions, Edward O'Connor, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions, Reiner Steib, 2009/03/05
- Re: Idempotency of add-hook wrt lambda expressions, David Kastrup, 2009/03/06
Re: Idempotency of add-hook wrt lambda expressions, Alan Mackenzie, 2009/03/05