From -4187446425428848706 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,96a8c01f7043c2d9 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2002-09-03 13:42:15 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!newsmi-us.news.garr.it!NewsITBone-GARR!area.cu.mi.it!news.mailgate.org!newsfeed.icl.net!newsfeed.fjserv.net!news-lond.gip.net!news.gsl.net!gip.net!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: terekhov@web.de (Alexander Terekhov) Newsgroups: comp.std.c++ Subject: Re: Proposal: exception stack unwinding resumption Date: Tue, 3 Sep 2002 20:42:14 +0000 (UTC) Organization: Demon Internet@Thus PLC Lines: 85 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: <3D751AAD.59EBC3F1@web.de> References: <6df0c6a8.0208260746.633710cb@posting.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: mail2news.demon.co.uk 1031085734 3042 10.0.0.1 (3 Sep 2002 20:42:14 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Tue, 3 Sep 2002 20:42:14 +0000 (UTC) X-Received: from mulga.cs.mu.oz.au ([128.250.1.22]) by news.demon.co.uk with esmtp (Exim 4.05) id 17mKV3-0000mv-00 for mail2news@news.news.demon.net; Tue, 03 Sep 2002 20:42:13 +0000 X-Received: from localhost (localhost [[UNIX: localhost]]) by mulga.cs.mu.OZ.AU id GAA02799; Wed, 4 Sep 2002 06:42:10 +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++@ncar.ucar.edu X-Newsgroups: comp.std.c++ X-Reply-To: terekhov@web.de X-Orig-NNTP-Posting-Host: ss4.bluebird.ibm.com (129.42.208.142) X-Orig-X-Trace: fu-berlin.de 1031084693 56813441 129.42.208.142 (16 [158401]) X-Accept-Language: en Xref: archiver1.google.com comp.std.c++:13583 Garry Lancaster wrote: [...] > I don't think the proposal adds enough to what we > already have to warrant its inclusion in the language. What about "bool future_std::expected_exception" and the entire "10 o'clock"-wish list: http://groups.google.com/groups?q=insubject:overloaded+insubject:destructors+author:terekhov%40web.de&scoring=d&filter=0 (Subject: Re: A half serious proposal: overloaded destructors) Oh, BTW, I've got one more "item"... < Forward Inline; FYI: http://www.gotw.ca/publications/xc++-errata.htm > -------- Original Message -------- Message-ID: <3D74BF08.AA0D377@web.de> Date: Tue, 03 Sep 2002 15:54:16 +0200 From: Alexander Terekhov Reply-To: terekhov@web.de Newsgroups: comp.lang.c++.moderated Subject: Re: "Exceptional C++", Item 5 (GoTW 16b, I think) Jim Fischer wrote: > > At the top of page 16 in Herb Sutter's book "Exceptional C++" he > mentions that a fixed_vector object will be in an inconsistent state if > one of the T assignments fails during the copy() operation. The text and > code on pp 16-18 takes some steps to address this issue. IMO, however, > the proposed "new-and-improved" code at the bottom of page 16 has > introduced a new exception-safety issue. Note that the templated > converting ctor and the copy ctor (p.16) both have the following form: > > fixed_vector( const fixed_vector& other ) > : v_( new T[size] ) > { > copy( other.begin(), other.end()+min(size,osize), begin() ); > } > > If the copy() call fails due to an exception being thrown, these ctors > will "leak" their dynamically allocated memory, right? Right, unless you prefer to use REAL objects vs "dumb" pointers; auto_ptr_array, in this case for "v_" member. Well, another RAII-less-approach that wouldn't "steal" each and every exception (as catch(...)/rethrow without ES protection unfortunately does), would be to use some currently nonexistent "soft"/"cleanup"-catch "construct": fixed_vector( const fixed_vector& other ) : v_( new T[size] ) { try { copy( other.begin(), other.end()+min(size,osize), begin() ); } catch(...) CLEANUP { /* THIS DOESN'T CATCH *UNEXPECTED* EXCEPTIONS */ /* THIS DOES RETHROW EXCEPTIONS AUTOMATICALLY */ /* NOTHING ELSE CAN BE THROWN FROM THIS BLOCK */ delete[] v_; } } http://groups.google.com/groups?threadm=Aiob9.18%24c7.126076%40news.cpqcorp.net (check out followup(s) as well; and, BTW, this entire thread is about exceptions and cleanup) regards, alexander. -- "~sentry(); 4 If ((os.flags() & ios base::unitbuf) && !uncaught exception()) is true, calls os.flush()." --ISO/IEC 14882:1998(E) Pg. 642 --- [ 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 ]