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Re: Table of "safe" methods to suppress "unused parameter" warnings?

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David Brown wrote:
> On 30/03/14 22:31, Ian Collins wrote:
>> Tim Rentsch wrote:
>>> Ian Collins <ian-news@hotmail.com> writes:
>>>
>>>> mathog wrote:
>>>>> Sometimes the same parameter list must be passed to a lot of different
>>>>> functions, and some of those will not use all of the parameters,
>>>>> resulting in some compilers emitting "unused parameter" warnings.  Here
>>>>> are all of the methods I have found so far for suppressing these:
>>>>
>>>> I wonder why C doesn't just follow C++ and allow unnamed parameters?
>>>
>>> Assuming for the sake of discussion that C did this, it
>>> still doesn't solve the problem, because sometimes you
>>> want the parameter name there but still have it not used,
>>> eg, when a function body has multiple definitions under
>>> control of a C preprocessor conditional.
>>
>> I disagree.  Allowing unnamed parameters would address the exact problem
>> stated in the question.  I don't see how multiple definitions under
>> control of a C preprocessor conditional would make a difference.  If an
>> "unused" parameter is used in the function body, you have a bug waiting
>> to happen.  It would be better to have it unnamed to allow the compiler
>> to spot the mistake.
>>
>> If you turn the argument on its head, why does C require parameters to
>> be named?  There doesn't appear to be any logical reason for this rule.
>
> I disagree (at least a bit) here - I don't see any reason to have
> unnamed parameters in C.  If the parameter is completely useless, then
> it should be removed entirely - if not, then the name is part of the
> documentation for the function's interface.  Just because it is not used
> in this particular version of the implementation of the function, does
> not mean it should not be named.

How so?  Consider for example a device driver interface that uses a 
struct of function pointers (a pretty common case).  All divers use the 
same struct, but not all divers require all of the parameters that are 
passed.  Having the parameter unnamed clearly documents that it is unused.

> And the solution to the original problem is nothing more dramatic than
> "(void) x;", which is neither hard to write nor hard to understand.

True, but it is ugly.  What possible harm could unnamed parameters cause?

> In C++, I can think of a situation where unnamed parameters make sense -
> you might want a function that requires you to have an object of a
> particular class but does not care about the contents.  This can be used
> to give compile-time checking of constraints.

Unnamed parameters are quite common in C++, probably more common than 
cases where they would be useful in C.  While the potential uses aren't 
a common in C, the feature would still be a useful, cost free, addition.


-- 
Ian Collins

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Table of "safe" methods to suppress "unused parameter" warnings? mathog <dmathog@gmail.com> - 2014-03-26 09:54 -0700
  Re: Table of "safe" methods to suppress "unused parameter" warnings? Barry Schwarz <schwarzb@dqel.com> - 2014-03-26 10:55 -0700
    Re: Table of "safe" methods to suppress "unused parameter" warnings? Keith Thompson <kst-u@mib.org> - 2014-03-26 11:13 -0700
    Re: Table of "safe" methods to suppress "unused parameter" warnings? Javier Lopez <j.lopezg@aol.com> - 2014-03-26 19:45 +0100
      Re: Table of "safe" methods to suppress "unused parameter" warnings? Kaz Kylheku <kaz@kylheku.com> - 2014-03-26 19:55 +0000
  Re: Table of "safe" methods to suppress "unused parameter" warnings? mathog <dmathog@gmail.com> - 2014-03-26 17:01 -0700
    Re: Table of "safe" methods to suppress "unused parameter" warnings? Javier Lopez <j.lopezg@aol.com> - 2014-03-27 01:46 +0100
      Re: Table of "safe" methods to suppress "unused parameter" warnings? Thomas Jahns <jahns@idontlikespam.dkrz.de> - 2014-03-27 09:34 +0100
        Re: Table of "safe" methods to suppress "unused parameter" warnings? gazelle@shell.xmission.com (Kenny McCormack) - 2014-03-27 10:52 +0000
        Re: Table of "safe" methods to suppress "unused parameter" warnings? David Brown <david.brown@hesbynett.no> - 2014-03-27 13:10 +0100
  Re: Table of "safe" methods to suppress "unused parameter" warnings? Ian Collins <ian-news@hotmail.com> - 2014-03-27 21:50 +1300
    Re: Table of "safe" methods to suppress "unused parameter" warnings? Tim Rentsch <txr@alumni.caltech.edu> - 2014-03-29 17:32 -0700
      Re: Table of "safe" methods to suppress "unused parameter" warnings? Ian Collins <ian-news@hotmail.com> - 2014-03-31 09:31 +1300
        Re: Table of "safe" methods to suppress "unused parameter" warnings? David Brown <david.brown@hesbynett.no> - 2014-03-31 11:31 +0200
          Re: Table of "safe" methods to suppress "unused parameter" warnings? Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-03-31 12:04 +0200
            Re: Table of "safe" methods to suppress "unused parameter" warnings? David Brown <david.brown@hesbynett.no> - 2014-03-31 13:55 +0200
              Re: Table of "safe" methods to suppress "unused parameter" warnings? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2014-04-01 02:04 +0300
                Re: Table of "safe" methods to suppress "unused parameter" warnings? Kaz Kylheku <kaz@kylheku.com> - 2014-03-31 23:37 +0000
                Re: Table of "safe" methods to suppress "unused parameter" warnings? David Brown <david.brown@hesbynett.no> - 2014-04-01 10:16 +0200
                Re: Table of "safe" methods to suppress "unused parameter" warnings? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2014-05-22 13:10 +0300
                Re: Table of "safe" methods to suppress "unused parameter" warnings? Kaz Kylheku <kaz@kylheku.com> - 2014-05-22 12:05 +0000
                Re: Table of "safe" methods to suppress "unused parameter" warnings? David Brown <david.brown@hesbynett.no> - 2014-04-01 09:59 +0200
          Re: Table of "safe" methods to suppress "unused parameter" warnings? Ian Collins <ian-news@hotmail.com> - 2014-03-31 23:17 +1300
            Re: Table of "safe" methods to suppress "unused parameter" warnings? David Brown <david.brown@hesbynett.no> - 2014-03-31 14:05 +0200
          Re: Table of "safe" methods to suppress "unused parameter" warnings? Kaz Kylheku <kaz@kylheku.com> - 2014-03-31 15:24 +0000
        Re: Table of "safe" methods to suppress "unused parameter" warnings? Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-15 04:26 -0700
          Re: Table of "safe" methods to suppress "unused parameter" warnings? Öö Tiib <ootiib@hot.ee> - 2014-04-23 07:31 -0700
            Re: Table of "safe" methods to suppress "unused parameter" warnings? Keith Thompson <kst-u@mib.org> - 2014-04-23 08:45 -0700
  Re: Table of "safe" methods to suppress "unused parameter" warnings? Tim Rentsch <txr@alumni.caltech.edu> - 2014-03-29 17:21 -0700
    Re: Table of "safe" methods to suppress "unused parameter" warnings? David Brown <david.brown@hesbynett.no> - 2014-03-31 13:26 +0200
      Re: Table of "safe" methods to suppress "unused parameter" warnings? James Kuyper <jameskuyper@verizon.net> - 2014-03-31 07:37 -0400
        Re: Table of "safe" methods to suppress "unused parameter" warnings? David Brown <david.brown@hesbynett.no> - 2014-03-31 14:12 +0200
      Re: Table of "safe" methods to suppress "unused parameter" warnings? Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-18 07:00 -0700
        Re: Table of "safe" methods to suppress "unused parameter" warnings? gazelle@shell.xmission.com (Kenny McCormack) - 2014-04-18 15:02 +0000
        Re: Table of "safe" methods to suppress "unused parameter" warnings? Keith Thompson <kst-u@mib.org> - 2014-04-18 08:58 -0700
          Re: Table of "safe" methods to suppress "unused parameter" warnings? Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-27 08:11 -0700
            Re: Table of "safe" methods to suppress "unused parameter" warnings? gazelle@shell.xmission.com (Kenny McCormack) - 2014-04-27 15:26 +0000
              Re: Table of "safe" methods to suppress "unused parameter" warnings? Tim Rentsch <txr@alumni.caltech.edu> - 2014-06-10 08:30 -0700
                Re: Table of "safe" methods to suppress "unused parameter" warnings? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2014-06-11 00:57 +0300
                Re: Table of "safe" methods to suppress "unused parameter" warnings? Ike Naar <ike@iceland.freeshell.org> - 2014-06-10 22:12 +0000
                Re: Table of "safe" methods to suppress "unused parameter" warnings? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2014-06-11 20:25 +0300
                Re: Table of "safe" methods to suppress "unused parameter" warnings? Martin Shobe <martin.shobe@yahoo.com> - 2014-06-10 18:59 -0500
                Re: Table of "safe" methods to suppress "unused parameter" warnings? Tim Rentsch <txr@alumni.caltech.edu> - 2014-06-11 21:22 -0700
            Re: Table of "safe" methods to suppress "unused parameter" warnings? Kaz Kylheku <kaz@kylheku.com> - 2014-04-28 01:40 +0000
        Re: Table of "safe" methods to suppress "unused parameter" warnings? David Brown <david.brown@hesbynett.no> - 2014-04-19 17:52 +0200
  Re: Table of "safe" methods to suppress "unused parameter" warnings? Siri Crews <chine.bleu@yahoo.com> - 2014-06-11 02:04 -0700

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