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Re: help with c-mode-common-hook


From: Hadron
Subject: Re: help with c-mode-common-hook
Date: Sun, 06 May 2007 20:29:22 +0200
User-agent: Gnus/5.110006 (No Gnus v0.6) Emacs/22.0.99 (gnu/linux)

Kai Grossjohann <address@hidden> writes:

> Hadron <address@hidden> writes:
>
>> Kai Grossjohann <address@hidden> writes:
>>
>>> Hadron <address@hidden> 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).


Thanks - I finally got it!


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