Consider the following two macros:
#define PNORM( v, s, ... ) { \
if( VERBOSITY_CHECK( v ) ) { \
if( ( errno = pthread_mutex_lock(&server.output_mutex) ) ) { \
PERROR_LOCKFREE( normal, "\tpthread_mutex_lock failed on output_mutex.\r\n" ) ; \
} \
fprintf( stdout, s, ## __VA_ARGS__ ) ; \
fflush( stdout ) ; \
if( ( errno = pthread_mutex_unlock(&server.output_mutex) ) ) { \
PERROR_LOCKFREE( normal, "\tpthread_mutex_unlock failed on output_mutex.\r\n" ) ; \
} \
} \
}
#define PERROR_LOCKFREE( v, s, ... ) { \
if( VERBOSITY_CHECK( v ) ) { \
PERRNO ;\
fprintf( stderr, s, ## __VA_ARGS__ ) ; \
fflush( stderr ) ; \
} \
}
Now consider an example use of these:
PNORM( verbose, "\tSomeText [%d] More [%p]\r\n", 0, ptr ) ;
When compiled with the -pedantic option and -std=c99 I get this error many times:
mycode.c:410:112: warning: ISO C99 requires rest arguments to be used
The complier is right in complaining about this but is there a simple way I can suppress this warning since I don't care about it?
Combine the s
argument with the variadic arguments so that you always have at least one argument as part of the ellipsis. This also allows you to avoid using the ,##
extension of GCC:
#define PNORM( v, ... ) { \
if( VERBOSITY_CHECK( v ) ) { \
if( ( errno = pthread_mutex_lock(&server.output_mutex) ) ) { \
PERROR_LOCKFREE( normal, "\tpthread_mutex_lock failed on output_mutex.\r\n" ) ; \
} \
fprintf( stdout, __VA_ARGS__ ) ; \
fflush( stdout ) ; \
if( ( errno = pthread_mutex_unlock(&server.output_mutex) ) ) { \
PERROR_LOCKFREE( normal, "\tpthread_mutex_unlock failed on output_mutex.\r\n" ) ; \
} \
} \
}
#define PERROR_LOCKFREE( v, ... ) { \
if( VERBOSITY_CHECK( v ) ) { \
PERRNO ;\
fprintf( stderr, __VA_ARGS__ ) ; \
fflush( stderr ) ; \
} \
}