A preprocessor feature we should have had 40 years ago

From	"Paul D. DeRocco" <pderocco@ix.netcom.com>
Newsgroups	comp.std.c, comp.std.c++
Subject	A preprocessor feature we should have had 40 years ago
Date	2013-05-23 19:18 -0600
Organization	unknown
Message-ID	<UrKdnTRjb8pONQDMnZ2dnUVZ_oudnZ2d@earthlink.com> (permalink)

Cross-posted to 2 groups.

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This is going to the C and C++ lists because it is equally applicable to
both.

I've occasionally needed to use the preprocessor to repeat a piece of
code some variable number of times. What would be so hard about
implementing this?

     #repeat <identifier> <const-expression>
     ...
     #endrepeat

The expression would be evaluated, and the contents of the block would
be repeated that number of times, with the preprocessor identifier
taking values 0 through n-1. Even with a fixed count, this can be useful:

     const int squares[] = {
     #repeat I 101
         I * I,
     #endrepeat
     };

Less trivial usages would of course involve counts that are themselves
preprocessor symbols or expressions. The only way to do this now is to
nest a lot of #if statements, up to some maximum size one might need,
and explicitly write the contents of each iteration.

-- 

Ciao,           Paul D. DeRocco
Paul            mailto:pderocco@ix.netcom.com


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A preprocessor feature we should have had 40 years ago "Paul D. DeRocco" <pderocco@ix.netcom.com> - 2013-05-23 19:18 -0600
  Re: A preprocessor feature we should have had 40 years ago Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-05-24 15:19 -0700
  Re: A preprocessor feature we should have had 40 years ago jacob navia <jacob@spamsink.net> - 2013-05-25 02:23 -0700
  Re: A preprocessor feature we should have had 40 years ago Keith Thompson <kst-u@mib.org> - 2013-05-25 02:24 -0700
    Re: A preprocessor feature we should have had 40 years ago "Kenneth \"Bessarion\" Boyd" <zaimoni@zaimoni.com> - 2013-05-25 23:43 -0700
    Re: A preprocessor feature we should have had 40 years ago "Paul D. DeRocco" <pderocco@ix.netcom.com> - 2013-05-25 23:44 -0700
      Re: A preprocessor feature we should have had 40 years ago Francis Glassborow <francis.glassborow@btinternet.com> - 2013-05-26 08:52 -0600
  Re: A preprocessor feature we should have had 40 years ago Rui Maciel <rui.maciel@googlemail.com> - 2013-05-25 23:43 -0700
  Re: A preprocessor feature we should have had 40 years ago Peter <pcurran88@googlemail.com> - 2013-05-30 19:40 -0600
    Re: A preprocessor feature we should have had 40 years ago "Paul D. DeRocco" <pderocco@ix.netcom.com> - 2013-06-01 02:04 -0600
      Re: A preprocessor feature we should have had 40 years ago ootiib@hot.ee - 2013-06-01 14:53 -0600
      Re: A preprocessor feature we should have had 40 years ago James Kuyper <jameskuyper@verizon.net> - 2013-06-04 10:41 -0600
        Re: A preprocessor feature we should have had 40 years ago espie@lain.home (Marc Espie) - 2013-06-05 23:12 -0700
          Re: A preprocessor feature we should have had 40 years ago James Kuyper <jameskuyper@verizon.net> - 2013-06-06 09:20 -0700
  Re: A preprocessor feature we should have had 40 years ago Jens Schweikhardt <usenet@schweikhardt.net> - 2013-06-09 02:21 -0700

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