CC-mode indentation after macros

CC-mode indentation after macros

[Ola Nilsson]

Hello,

I'm working with code that contains a number of debug
macros. Typically the look like this:

#ifdef DEBUG 
#define DEB(x) x 
#else 
#define DEB(x) 
#endif

These are used in the code like this:

void foo(void) 
{ 
  ...
  DEB(printf("Debug print";) 
  ...
}


That is, in many places the semicolon is inside the macro not outside
(that would generate empty statements that lint would complain over).

Now, my problem is that cc-mode wants to indent the next line, but I
would like to have int on the same indentation level as the DEB
line. How can I get this behaviour? Do I need to add regexps for the
DEB() types of macros? And in that case, where should I add them?

Thanks for any help,
-- 
/Ola Nilsson

Re: CC-mode indentation after macros

[Star Watcher]

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If you're lucky enough to be using gcc's cpp preprocessor, I suggest you
take a look at its powerful "variadic macros" extensions.
Among other things, it will allow you to write elegant things like that:

#ifdef DEBUG
#define PRINTF(_X_,_ARGS_...)    printf(_X_,## _ARGS_)
#else
#define PRINTF(_X_,_ARGS_...)    do{}while(0)
#endif

/*...*/
void foo(void)
{
  ...
  PRINTF("Debug print");
  ...
}

This will both avoid breaking cc-mode's indentation scheme AND make the code
look better (IMHO).
The do{}while(0) statement does not generate warnings with gcc -Wall, I
wonder if it fools lint also.
There are other C preprocessors that also support variadic macros... (see
manual)
--
Laurent

"Ola Nilsson" <sds024five1@sydpost.nospam.nu> a écrit dans le message de
news:87oeiz16lf.fsf@helmut.nilsson.homedns.org...
> Hello,
>
> I'm working with code that contains a number of debug
> macros. Typically the look like this:
>
> #ifdef DEBUG
> #define DEB(x) x
> #else
> #define DEB(x)
> #endif
>
> These are used in the code like this:
>
> void foo(void)
> {
>   ...
>   DEB(printf("Debug print";)
>   ...
> }
>
>
> That is, in many places the semicolon is inside the macro not outside
> (that would generate empty statements that lint would complain over).
>
> Now, my problem is that cc-mode wants to indent the next line, but I
> would like to have int on the same indentation level as the DEB
> line. How can I get this behaviour? Do I need to add regexps for the
> DEB() types of macros? And in that case, where should I add them?
>
> Thanks for any help,
> -- 
> /Ola Nilsson

Re: CC-mode indentation after macros

[Ola Nilsson]

Ola Nilsson <sds024five1@sydpost.nospam.nu> writes:

> I'm working with code that contains a number of debug
> macros. Typically the look like this:
>
> #ifdef DEBUG 
> #define DEB(x) x 
> #else 
> #define DEB(x) 
> #endif
>
> These are used in the code like this:
>
> void foo(void) 
> { 
>   ...
>   DEB(printf("Debug print";) 
>   ...
> }
>
> That is, in many places the semicolon is inside the macro not outside
> (that would generate empty statements that lint would complain over).
>
> Now, my problem is that cc-mode wants to indent the next line, but I
> would like to have int on the same indentation level as the DEB
> line. How can I get this behaviour? Do I need to add regexps for the
> DEB() types of macros? And in that case, where should I add them?

First, thanks Laurent for your reply. Unfortunately I'm not useing GCC
for the code described. If it was only my project, I would easily
adopt your suggestion.

I seem to have found something that works for me, the statement-cont
indentation configuration. So far it seems to do what I want. I added:

  (c-set-offset 'statement-cont 0)

to my c-mode hook. Now the line after the DEB macro get's indented
like I want. There is probably some draw back that I've not yet found,
but so far so good.

And I got to try the lisp debugger and debug-on-entry ;-)

Again, thanks!
-- 
/Ola Nilsson

Re: CC-mode indentation after macros

[Stefan Monnier]

> #ifdef DEBUG
> #define DEB(x) x
> #else
> #define DEB(x)
> #endif

> These are used in the code like this:

> void foo(void) 
> { 
>   ...
>   DEB(printf("Debug print";) 
>   ...
> }

> That is, in many places the semicolon is inside the macro not outside
> (that would generate empty statements that lint would complain over).

Then run lint with DEBUG enabled so the statements aren't empty.


        Stefan