From 2247638188808121229 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,49dc144769c6b88f X-Google-Attributes: gidf78e5,public From: David Bruce Subject: Empty objects (was Re: Are there any plans to make "properties" standard?) Date: 1999/06/25 Message-ID: <37734C93.672DA531@dera.gov.uk>#1/1 X-Deja-AN: 493792437 X-Nntp-Posting-Host: signal.dera.gov.uk Content-Transfer-Encoding: 7bit Approved: stephen.clamage@sun.com (comp.std.c++) References: <7jprhq$e8r@cocoa.brown.edu> <376278B4.C9EDDB26@acm.org> X-Accept-Language: en-GB, en, en-US Content-Type: text/plain; charset=us-ascii Organization: DERA Malvern Mime-Version: 1.0 Newsgroups: comp.std.c++ Originator: clamage@taumet Pete Becker wrote (apropos Jerry Coffin's observation that properties can naturally be encoded in C++ using objects): > Yup. And if you do this through objects, then the containing class can > end up with a half-dozen (perhaps, often many more) empty objects as > members, inflating its size. Right, so the real question for c.s.c++ is not ``how do we do properties'' but rather ``what changes would need to be made to C++ to allow this natural use of objects to be implemented (space) efficiently'', this being not only the root cause but also a more general problem. I'm aware that the issue is that (member) objects are not permitted to have the same address, so I guess I'm asking *why* that's so important, and what an alternative C++ where it wasn't the case would look like. For example, given that C++ has references, when do we really need to take the address of (member) objects (as distinct from their pointer-to-member `address')? (Identity comparisons are perhaps the most obvious case, but maybe if one could compare objects for identity directly -- e.g., a non-overloadable operator=== ? -- rather than by comparing their addresses this might be less significant.) What else could go wrong if two (member) objects did have the same address? Sincerely, David Bruce ________________________________________________________________________ post: DERA Malvern, St Andrews Road, Malvern, WORCS WR14 3PS, ENGLAND mailto:dib@dera.gov.uk ** phone: +44 1684 895112 ** fax: +44 1684 894389 [The views expressed above are entirely those of the writer and do not represent the views, policy or understanding of any other person or official body.] [ 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://reality.sgi.com/austern_mti/std-c++/faq.html ]