From -3080038566497142524 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,307cbe6f0ea2ccd3 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2003-06-09 16:05:42 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: andreytarasevich@hotmail.com (Andrey Tarasevich) Newsgroups: comp.std.c++ Subject: Re: Recommendation to the Standards Committee Date: Mon, 9 Jun 2003 23:05:41 +0000 (UTC) Organization: Posted via Supernews, http://www.supernews.com Lines: 63 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: <3EE506BB.3050909@hotmail.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit X-Trace: mail2news.demon.co.uk 1055199941 18408 10.0.0.1 (9 Jun 2003 23:05:41 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Mon, 9 Jun 2003 23:05:41 +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 19PVhs-0004ml-00 for mail2news@news.news.demon.net; Mon, 09 Jun 2003 23:05:40 +0000 X-Received: by mulga.cs.mu.OZ.AU id JAA06115; Tue, 10 Jun 2003 09:05:37 +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-User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0 X-Accept-Language: en-us, en X-Spam-Status: No, hits=-11.3 required=5.0 tests=FORGED_HOTMAIL_RCVD,NOSPAM_INC,QUOTED_EMAIL_TEXT, REFERENCES,SIGNATURE_SHORT_DENSE,SPAM_PHRASE_03_05, USER_AGENT,USER_AGENT_MOZILLA_UA,X_ACCEPT_LANG version=2.41 Xref: archiver1.google.com comp.std.c++:19671 Brian Plummer wrote: > ... > Well, almost all of the code I write is portable to a large number of > Hardware/OS/Compiler combinations and I (try to) employ a technique to > reduce compile times discussed by Lakos on pages 82-88 of "Large Scale C++ > Software Design" which advocates protecting every #include file directive > with a redundant check for previous inclusion of said header in the > translation unit. An example could be: > > #ifndef __IOSTREAM__ > #include > #endif > > This is what I would use if I was using the cygwin hosted gcc 3.1 that is > installed on my Windows machine. If I want to accomplish this same thing > with MSVC (Microsoft Visual Studio .NET 2003) I would have to use the > following: > > #ifndef _IOSTREAM_ > #include > #endif > > The problem here is that the MSVC header guard for iostream only uses one > (1) underscore instead of 2 as in the gcc header guard for iostream. So, if > I compile my code using the gcc header guard check as displayed in the first > example with MSVC, my attempt at eliminating redundant inclusion fails, > silently, because the header guards are different. > > I'm assuming that you are familiar with this technique. If not, you should > take a quick look at the pages I site from Lakos. Its a very > straight-forward technique and when carefully employed it can dramatically > reduce compile times on large projects, especially if the standard library > headers are widely referred to in the project's header files which is > becoming ever more prevalent with the exploding use of template classes and > functions. > > If the header guard text was standardized then I can employ this technique > without having to worry about how Library Vendor X has assembled the header > guard text. > ... Well, since you are already doing as much as putting this '#ifndef'/'#endif' guard _outside_ the header file (i.e. add it to every '#include' that refers to this file), it really won't make things much harder if you add an additional '#define' into the mix. Just make up your own guard names for every header file and use them like this: #ifndef MY_IOSTREAM_INCLUDED_ #define MY_IOSTREAM_INCLUDED_ #include #endif // MY_IOSTREAM_INCLUDED_ -- Best regards, Andrey Tarasevich Brainbench C and C++ Programming MVP --- [ 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 ]