Re: Usage of pre-processor macro.

James Kanze <>
Sun, 4 Jul 2010 04:00:31 -0700 (PDT)
On Jun 30, 10:16 pm, Pete Becker <> wrote:

On 2010-06-30 17:03:20 -0400, Pete Becker said:

On 2010-06-30 16:42:54 -0400, Alf P. Steinbach /Usenet said:

I don't think the argument holds in general, because it's
so very rare to intentionally not use a formal argument.

On the contrary: it's quite common in certain coding styles.
One example was mentioned earlier in this thread. To
elaborate a bit: a polymorphic function whose base version
doesn't do anything, but is overridden sometimes to actually
use its arguments presents exactly this case.

Even more to the point is that this is utterly trivial. If I
meant to not use a parameter, time spent telling the compiler
that that's what I meant is simply wasted.

Even the time spent giving it a name in the first place is
wasted. And if you don't give it a name, you shouldn't get the
warning. However...

If I should have used it, unit tests will detect the error.

More importantly: in my experience, inverting the parameters (in
this case) is a far more frequent error. Which the warning
won't detect, but even the most trivial unit test should. The
warning is worthless, but because you don't have to give the
parameter a name (and not giving it a name is the consacrated
way of saying that you don't use it), it's generally not worth
the bother of turning it off. (For parameters. I did use a
compiler in the past that warned about local variables not being
used, even if they had a non-trivial destructor. In other
words, most uses of RAII would trigger a warning.)

James Kanze

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