From 1150313290263526835 X-Google-Thread: f78e5,a10702d4a7db0a94 X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news2.google.com!news4.google.com!news3.google.com!news.glorb.com!news.alt.net!comp-std-cpp-robomod!not-for-mail From: "Greg Herlihy" Newsgroups: comp.std.c++ Subject: Re: Why no size_t to ::operator delete? Date: Sun, 24 Dec 2006 11:45:56 CST Organization: http://groups.google.com Lines: 31 Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: <1166953289.859132.240450@i12g2000cwa.googlegroups.com> References: <12omt8jit7rl379@corp.supernews.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Trace: posting.google.com 1166953294 22176 127.0.0.1 (24 Dec 2006 09:41:34 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Sun, 24 Dec 2006 09:41:34 +0000 (UTC) Return-Path: X-Authentication-Warning: mulga.csse.unimelb.edu.au: fjh set sender to devnull@stump.algebra.com using -f X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-Original-To: std-c++@mailman.ucar.edu Delivered-To: std-c++@mailman.ucar.edu User-Agent: G2/1.0 X-HTTP-UserAgent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en) AppleWebKit/418.9.1 (KHTML, like Gecko) Safari/419.3,gzip(gfe),gzip(gfe) Complaints-To: groups-abuse@google.com Injection-Info: i12g2000cwa.googlegroups.com; posting-host=70.231.133.91; posting-account=JdllFQ0AAAC-QghphnHMZz5q0GHnzGUJ X-Virus-Scanned: amavisd-new at ucar.edu X-Virus-Scanned: amavisd-new at csse.unimelb.edu.au X-Virus-Scanned: amavisd-new at csse.unimelb.edu.au Xref: g2news2.google.com comp.std.c++:5162 Scott Meyers wrote: > Can someone explain to me why having the "normal" operator delete take a > size_t is impractical? Since the implementation of a class-specific delete operator always has the option of calling the global delete operator to perform the actual deallocation, a class delete operator does have a good excuse for not knowing the actual size of the block being deleted. Therefore, knowing the size of the original allocation request very well could be information that the class delete operator could not otherwise find out on its own. The global delete operator has no comparable back-up, there is no other delete routine that it can call to free the memory - global delete must free the block itself. And in order to free the block, the global delete operator must know the size of the actual allocation; knowing just the requested size alone (the value of the size parameter) is not enough information to free the block. Even assuming that the value of the size parameter is accurate in the first place. After all, the correctness of a program's memory management should not depend upon the faithful preservation of data points that are needlessly round-tripped through the user program, or so I would think. Greg --- [ 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.comeaucomputing.com/csc/faq.html ]