unofficial mirror of help-gnu-emacs@gnu.org
 help / color / mirror / Atom feed
From: Kai Grossjohann <kai@emptydomain.de>
To: help-gnu-emacs@gnu.org
Subject: Re: help with c-mode-common-hook
Date: Thu, 03 May 2007 17:42:48 +0200	[thread overview]
Message-ID: <86hcqtykuf.fsf@ketchup.de.uu.net> (raw)
In-Reply-To: 87abwmdkul.fsf@gmail.com

Hadron <hadronquark@gmail.com> writes:

> Kai Grossjohann <kai@emptydomain.de> writes:
>
>> Hadron <hadronquark@gmail.com> writes:
>>
>>> I'm not sure what ellided means. But how come it works in my direct
>>> add-hook then? The "old" way was working before (famous last words :-;).
>>
>> The "direct" method works because you have different code in that
>> case.
>>
>> To make the "direct" method fail, you need to do this:
>>
>> (add-hook 'c-mode-common-hook 
>>           (lambda ()
>>             (lambda ()
>>               ...same code as before)))
>>
>> As you can see, there is one lambda too many.
>>
>
> But there wasnt 2 lambdas in my other way:
>
> | (defun my-compile ()
> |   (message "in my-compile")
> |   (lambda () [...]
> |   )
>
> Am I missing something glaringly obvious here?

defun has an implicit lambda -- sorry if that wasn't clear.  Perhaps I
explain it with Scheme (Pidgin Scheme, I haven't used actual Scheme
for at least 15 years) first:

(define (foo) ...) is the same as (setq foo (lambda () ...)).  Thus,
(define (foo) (lambda () ...)) is the same as (setq foo (lambda ()
(lambda () ...))).

In Emacs Lisp, it looks less symmetric:

(defun foo () ...) is the same as (fset foo (lambda() ...)).  Thus,
(defun foo () (lambda () ...)) is the same as (fset foo (lambda ()
(lambda () ...))).

To be concrete: my-compile is a function that, when called, does the
following: first, it prints something.  Then it returns a function.
The function it returns would, if it were ever called, do useful
things.  However, it is never called -- the return value of my-compile
is discarded (when my-compile is added to a hook and then the hook is
run).

Kai

  reply	other threads:[~2007-05-03 15:42 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-02 18:00 help with c-mode-common-hook Hadron
2007-05-02 18:22 ` Robert Thorpe
2007-05-02 18:37   ` Hadron
2007-05-03  0:24     ` Hadron
2007-05-03  6:26       ` Kevin Rodgers
     [not found]       ` <mailman.158.1178174006.32220.help-gnu-emacs@gnu.org>
2007-05-03 10:08         ` Hadron
2007-05-03 14:09           ` Kai Grossjohann
     [not found]           ` <mailman.175.1178201800.32220.help-gnu-emacs@gnu.org>
2007-05-03 14:48             ` Hadron
2007-05-03 15:42               ` Kai Grossjohann [this message]
2007-05-03 17:11               ` Robert Thorpe
     [not found]               ` <mailman.180.1178207394.32220.help-gnu-emacs@gnu.org>
2007-05-06 18:29                 ` Hadron

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=86hcqtykuf.fsf@ketchup.de.uu.net \
    --to=kai@emptydomain.de \
    --cc=help-gnu-emacs@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.
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).