From -5153011158419507000 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,206db806b836bf67 X-Google-Attributes: gidf78e5,public From: msherman@magma.ca (Marc Sherman) Subject: Re: Pointers to incomplete type Date: 1998/01/19 Message-ID: <6a0a4g$rf1@shell.magma.ca>#1/1 X-Deja-AN: 317463650 References: <69osom$jf3@examiner.concentric.net> X-Original-Date: 19 Jan 1998 14:38:56 -0500 Organization: Magma Communications Ltd., Nepean, Ontario, Canada X-Auth: PGPMoose V1.1 PGP comp.std.c++ iQBFAgUANMPKGeEDnX0m9pzZAQH7EgF8CMYlfsaA09INcx8QR1R4Y8yEWlEfuYRO QE9Rj3VeMduDFlOwABBz92dWK9YwudZM =9A+9 Reply-To: msherman@magmacom.com Newsgroups: comp.std.c++ In article <69osom$jf3@examiner.concentric.net>, Bradd W. Szonye wrote: > Under an alternate object model: > 1. sizeof(poly) == sizeof(pod) > 2. sizeof(poly[1000]) == sizeof(pod[1000]) > 3. sizeof(poly *) == 8 // vptr + address > 4. sizeof(pod *) == 4 > 5. minimum sizeof(vector::iterator) == 4 > 6. minimum sizeof(set::iterator) == 4 > >Some notes: where I'd expect the big win is in #2: the savings of not >putting vtable pointers in heavily-allocated, lightweight objects. (Also, Is case 2 very likely? Since we're talking about polymorphic objects, aren't we much more likely to have poly*[1000] than poly[1000]? If we have a large array of pointers to poly, your new model would in fact take up more space than the standard model does. - Marc --- [ 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 ] [ FAQ: http://reality.sgi.com/employees/austern_mti/std-c++/faq.html ] [ Policy: http://reality.sgi.com/employees/austern_mti/std-c++/policy.html ] [ Comments? mailto:std-c++-request@ncar.ucar.edu ]