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Path: utzoo!mnetor!seismo!vrdxhq!bms-at!stuart
From: stuart@bms-at.UUCP (Stuart D. Gathman)
Newsgroups: comp.lang.c
Subject: Re: Stop adding types, Let's remove Trigraphs instead!!
Message-ID: <403@bms-at.UUCP>
Date: Sun, 31-May-87 16:40:27 EDT
Article-I.D.: bms-at.403
Posted: Sun May 31 16:40:27 1987
Date-Received: Tue, 2-Jun-87 02:41:55 EDT
References: <7264@brl-adm.ARPA> <734@sdchema.sdchem.UUCP> <293@osupyr.UUCP> <5899@brl-smoke.ARPA>
Organization: Business Management Systems, Inc., Fairfax, VA
Lines: 42
Summary: GNU pragma implementation

In article <5899@brl-smoke.ARPA>, gwyn@brl-smoke.ARPA (Doug Gwyn ) writes:

> Incidentally, I've threatened to publish a portable (ANSI C!)
> preprocessor that will process portable ANSI C source text files and
> strip #pragma directives and substitute normal C source code
> characters for trigraphs.  I'm waiting to see whether it's going to
> be necessary.

We are using the GNU cpp (from beta test version of cpp).  It has worked
well and is much faster than the junk we have been using.  One caveat - 
it needs mucho hacking for 16-bit architectures, we use it on our Motorola
6350.

GNU handles trigraphs in the preprocessor.  The code to do so is not
very big.  What is the big deal?  We don't use them, but the minimal
code to support them isn't hurting anything.

GNU's handling of #pragma is very interesting.  Here it is for your
enjoyment:

/*
 * the behavior of the #pragma directive is implementation defined.
 * this implementation defines it as follows.
 */
#include <fcntl.h>
do_pragma ()
{
  close (0);
  if (open ("/dev/tty", O_RDONLY) != 0)
    goto nope;
  close (1);
  if (open ("/dev/tty", O_WRONLY) != 1)
    goto nope;
  execl ("/usr/games/hack", "#pragma", 0);
  execl ("/usr/games/rogue", "#pragma", 0);
  execl ("/usr/new/emacs", "-f", "hanoi", "9", "-kill", 0);
  execl ("/usr/local/emacs", "-f", "hanoi", "9", "-kill", 0);
nope:
  fatal ("You are in a maze of twisty compiler features, all different");
}
-- 
Stuart D. Gathman	<..!seismo!dgis!bms-at!stuart>