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From: Pascal J. Bourguignon on 4 Aug 2010 06:27
Fren Zeee <frenzeee(a)gmail.com> writes:

> On Aug 2, 5:31�pm, "Daniel (Youngwhan)" <breadn...(a)gmail.com> wrote:
>> Hi,
>>
>> If there is curly brace, it is easy to navigate between them by M-C-f
>> and M-C-b in c-mode.
>>
>> However, I cannot find a way to navigate in like curly brace when it
>> comes to #ifdef, #else, and #endif.
>>
>> For example, if there is a code like this:
>>
>> #ifdef A_DEFINED
>> (...100 lines)
>> #else
>> (... 500 lines)
>> #endif
>>
>> , is there a easy way to move the cursor from #endif to #ifdef or
>> #else and vice versa?
>>
>> Daniel
>
> You might get better luck posting in a C group also.
>
> I use #ifdef ... #endif often also to comment out blocks of code
> during debugging.
>
> My question to CLISP/ELISP/scheme people is

clisp is an implementation, not a language.

There is a language named Common Lisp, abreviated as CL. Perhaps you
mean that?



> If there is a wrapper do nothing type function in elisp/clisp/scheme
> which can have the same effect as commenting out.
>
> This is because I dont like to do comment-region/uncomment-region in
> emacs.
>
> These three lispy languages dont seem to have comment block construct
> like C ie /* and */

AFAIK, emacs lisp doesn't have any block comment feature, and I know
no standard way to do block comment in r5rs scheme, but scheme
implementation may provide the same as in Common Lisp, or with a
different syntax.

In Common Lisp you could try to use #| |#, but unfortunately, it is not like C /* and */:

int a[]={
/* hello
/* world
*/
1,2};
// a contains {1,2}.


(let ((a '(
#| hello
#| world
|#
1 2)))
a)

is a syntactic error.


You would have to write:

(let ((a '(
#| hello
#| world |#
|#
1 2)))
a)
--> (1 2)



However, in Common Lisp, you could implement a reader macro with a
behavior similar to C /* comments */.

This is the reason why there is no point asking whether there is a
feature X in CL. You can always add any feature to the language,
thanks to its macros or reader macros, and metalinguistic abilities in
general.


--
__Pascal Bourguignon__ http://www.informatimago.com/
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