From 4150922655196054535 X-Google-Thread: f78e5,6978327f896d5d5b X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news2.google.com!proxad.net!fr.ip.ndsoftware.net!newsfeed00.sul.t-online.de!t-online.de!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: pjp@dinkumware.com ("P.J. Plauger") Newsgroups: comp.std.c++ Subject: Re: What is the use of the null directive # ? Date: Mon, 28 Jun 2004 05:36:01 +0000 (UTC) Lines: 58 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: <2VIDc.8800$DT5.5297@nwrddc03.gnilink.net> References: <607f883e.0406251028.5412fc80@posting.google.com> X-Trace: mail2news.demon.co.uk 1088400961 21881 10.0.0.1 (28 Jun 2004 05:36:01 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Mon, 28 Jun 2004 05:36:01 +0000 (UTC) X-Received: from mulga.cs.mu.oz.au ([128.250.1.22]) by news.demon.co.uk with esmtp (Exim 4.12) id 1BeooC-0005gm-00 for mail2news@news.news.demon.net; Mon, 28 Jun 2004 05:36:00 +0000 X-Received: from mulga.cs.mu.OZ.AU (localhost [127.0.0.1]) by mulga.cs.mu.OZ.AU with ESMTP id i5S5Zvb9026695; Mon, 28 Jun 2004 15:35:57 +1000 (EST) X-Received: (from fjh@localhost) by mulga.cs.mu.OZ.AU (8.12.10+Sun/8.12.9/Submit) id i5S5Zu4L026685; Mon, 28 Jun 2004 15:35:56 +1000 (EST) X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Path: comp-std-cpp-robomod!not-for-mail X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-Delivered-To: std-c++@ucar.edu X-Newsgroups: comp.std.c++ X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-NNTP-Posting-Date: Sun, 27 Jun 2004 19:39:42 EDT X-Spam-Checker-Version: SpamAssassin 2.60-mulga_r1 (1.212-2003-09-23-exp) on mulga.cs.mu.OZ.AU X-Spam-Level: X-Spam-Status: No, hits=-2.7 required=5.2 tests=AWL,BAYES_00, MAILTO_TO_SPAM_ADDR,PRIORITY_NO_NAME autolearn=no version=2.60-mulga_r1 Xref: g2news1.google.com comp.std.c++:1050 "Francis Glassborow" wrote in message news:Bt9PFkEEEq3AFwhq@robinton.demon.co.uk... > In article , > Barry Margolin writes > >In article , > > francis@robinton.demon.co.uk (Francis Glassborow) wrote: > > > >> In article <607f883e.0406251028.5412fc80@posting.google.com>, Prateek R > >> Karandikar writes > >> >What is the use of the null-directive # ? > >> > > >> > > >> > 16.7 Null directive [cpp.null] > >> >1 A preprocessing directive of the form > >> > # new-line > >> > has no effect. > >> > > >> > >> It allows implementors to add directives as extensions without having > >> impact on the portability of code using them. > > > >All it says is that the line: > > > ># > > > >is ignored. How does that allow an implementor to add something like: > > > >#foobar > > No it does not say that the implementor is _required_ to ignore such a > directive. What it does say is that such a directive is not cause to > abort compilation, nor does its existence require a diagnostic. > > It generalises the #pragma directive so that I can write: > > #packed > > happy in the knowledge that any compiler that does not understand that > directive will simply ignore it. I have trouble reading it that way. Where in the grammar : # new-line is there wiggle room to add the word 'packed', or any other non-whitespace thingy? P.J. Plauger Dinkumware, Ltd. http://www.dinkumware.com --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ]