Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #15902

Re: macro

Show all headers | View raw

On 01/18/12 10:05 PM, dspfun wrote:
> On 18 Jan, 01:12, Ian Collins<ian-n...@hotmail.com>  wrote:
>> On 01/18/12 10:05 AM, Keith Thompson wrote:

[what adds these random lines?]

>>> Philip Lantz<p...@canterey.us>    writes:
>>
>>>> I think one of the main reasons for me is that using do ... while (0) in
>>>> a macro is a hack, and I try to avoid using hacks except where
>>>> necessary, and it is (in my experience) almost never necessary.
>>
>>> Fair enough.
>>
>>> But one could argue that translating if/else to ?: and ";" to "," for
>>> the sole purpose of making a chunk of code usable as a macro is equally
>>> hackish.
>>
>>> Sure, "do...while(0)" is a hack -- but it's also an idiom that's widely
>>> used and recognized by C programmers.
>>
>> It is also a strong indication that whatever you are attempting to do is
>> an inappropriate use of a macro!
>>
> What is the reason that this is an indication that the "do...while(0)"
> in a macro is an inappropriate use of a macro?

Because in most cases it gets used where a function or as in your code, 
a macro wrapping a function, is more appropriate.  The rare exceptions 
are where macros are used as poor man's templates.

I guess the use of "do...while(0)" (and function-like macros in general) 
is a hang over from 80s and 90s compiler which didn't inline functions.

-- 
Ian Collins

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

macro dspfun <dspfun@hotmail.com> - 2012-01-15 05:29 -0800
  Re: macro Dr Nick <3-nospam@temporary-address.org.uk> - 2012-01-15 13:44 +0000
    Re: macro dspfun <dspfun@hotmail.com> - 2012-01-15 05:58 -0800
      Re: macro "Joachim Schmitz" <nospam.jojo@schmitz-digital.de> - 2012-01-15 15:34 +0100
      Re: macro "christian.bau" <christian.bau@cbau.wanadoo.co.uk> - 2012-01-15 06:37 -0800
        Re: macro dspfun <dspfun@hotmail.com> - 2012-01-15 07:28 -0800
          Re: macro Philip Lantz <prl@canterey.us> - 2012-01-15 17:30 -0800
            Re: macro Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-16 00:18 -0800
              Re: macro Hans Vlems <hvlems@freenet.de> - 2012-01-16 00:52 -0800
                Re: macro Ian Collins <ian-news@hotmail.com> - 2012-01-16 22:08 +1300
                Re: macro Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-16 03:04 -0800
                Re: macro Markus Wichmann <nullplan@gmx.net> - 2012-01-16 12:42 +0100
        Re: macro jgk@panix.com (Joe keane) - 2012-01-16 14:48 +0000
          Re: macro Keith Thompson <kst-u@mib.org> - 2012-01-16 12:01 -0800
            Re: macro Philip Lantz <prl@canterey.us> - 2012-01-17 01:02 -0800
              Re: macro Keith Thompson <kst-u@mib.org> - 2012-01-17 13:05 -0800
                Re: macro Ian Collins <ian-news@hotmail.com> - 2012-01-18 13:12 +1300
                Re: macro dspfun <dspfun@hotmail.com> - 2012-01-18 01:05 -0800
                Re: macro Ian Collins <ian-news@hotmail.com> - 2012-01-18 22:57 +1300
                Re: macro "osmium" <r124c4u102@comcast.net> - 2012-01-18 06:22 -0600
                Re: macro dspfun <dspfun@hotmail.com> - 2012-01-18 07:50 -0800
                Re: macro Ian Collins <ian-news@hotmail.com> - 2012-01-20 14:09 +1300
                Re: macro blp@cs.stanford.edu (Ben Pfaff) - 2012-01-18 11:28 -0800
                Re: macro Kaz Kylheku <kaz@kylheku.com> - 2012-01-18 21:09 +0000
                Re: macro Ian Collins <ian-news@hotmail.com> - 2012-01-20 15:08 +1300
                [OT] Re: macro Ian Collins <ian-news@hotmail.com> - 2012-01-20 15:58 +1300
                Re: [OT] Re: macro Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-01-20 12:22 +0000
                Re: [OT] Re: macro Ian Collins <ian-news@hotmail.com> - 2012-01-21 07:58 +1300
                Re: macro James Kuyper <jameskuyper@verizon.net> - 2012-01-19 22:47 -0500
                Re: macro Ian Collins <ian-news@hotmail.com> - 2012-01-20 17:06 +1300
                Re: macro James Kuyper <jameskuyper@verizon.net> - 2012-01-20 00:12 -0500
                Re: macro Ian Collins <ian-news@hotmail.com> - 2012-01-20 18:28 +1300
                Re: macro Keith Thompson <kst-u@mib.org> - 2012-01-20 03:21 -0800
                Re: macro Shao Miller <sha0.miller@gmail.com> - 2012-01-20 10:50 -0500
                Re: macro Shao Miller <sha0.miller@gmail.com> - 2012-01-20 11:46 -0500
                Re: macro Keith Thompson <kst-u@mib.org> - 2012-01-18 14:24 -0800
                Re: macro jgk@panix.com (Joe keane) - 2012-01-18 22:36 +0000
                Re: macro Kaz Kylheku <kaz@kylheku.com> - 2012-01-18 22:50 +0000
            Re: macro jgk@panix.com (Joe keane) - 2012-01-17 22:08 +0000
  Re: macro Keith Thompson <kst-u@mib.org> - 2012-01-15 08:00 -0800
  Re: macro NEON China BLUE <chine.bleu@yahoo.com> - 2012-01-15 08:15 -0800
  Re: macro Ian Collins <ian-news@hotmail.com> - 2012-01-16 09:04 +1300
    Re: macro Philip Lantz <prl@canterey.us> - 2012-01-15 17:36 -0800
  Re: macro Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-16 12:01 +0000

csiph-web