Re: void

From:

Pete Becker <pete@versatilecoding.com>

Newsgroups:

comp.lang.c++

Date:

Sat, 17 Feb 2007 10:19:02 -0500

Message-ID:

<UuCdnSz97qV6gUrYnZ2dnUVZ_vvinZ2d@giganews.com>

Dave Rahardja wrote:

On Sat, 17 Feb 2007 08:03:01 -0500, Pete Becker <pete@versatilecoding.com>
wrote:

hyderabadblues wrote:

What does (void) poService in followinf peace of code mean

tclCtrlBoard::tclCtrlBoard( void* poService )
{

# if defined Something
(void) poService; \\ What does this mean

}

It's a workaround for a compiler warning that the argument poService is
not used. It tells the compiler to evaluate the expression poService and
to ignore it. Isn't it wonderful what people do to cope with busybody
compilers?

That busybody compiler feature was probably added as a warning that helps you
find bugs.

It was added as a warning that some comiler writer thought might help
find bugs, but it's really a matter of enforcing someone's notion of
good coding style. If your ideas of good style differ, you end up
fighting with the compiler.

If the OP wants to get rid of the warning, change the function's
definition to:

tclCtrlBoard::tclCtrlBoard(void*)
{
}

Sometimes certain input parameters are only during debug builds. In that case
I tend to use:

#if defined(DEBUG)
#define DEBUG_VAR(x) (x)
#else
#define DEBUG_VAR(x)
#endif

tclCtrlBoard::tclCtrlBoard(void* DEBUG_VAR(poService))
{
#if defined DEBUG
// Use poService for debugging
VERIFY(poService == 0);
#endif
}

All that, just because some compiler writer decided that he knows better
than you do what you meant to write? I prefer to turn off stylistic
warnings like this one.

--

-- Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com)
Author of "The Standard C++ Library Extensions: a Tutorial and
Reference." (www.petebecker.com/tr1book)