From 6306263352190542634 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,942dd48e323646a4 X-Google-Attributes: gidf78e5,public From: Francis Glassborow Subject: Re: const static member in a class Date: 2000/05/29 Message-ID: #1/1 X-Deja-AN: 628434417 Approved: Fergus Henderson , moderator of comp.std.c++ References: <3908CCBC.E02307C@hotmail.com> <392E5925.6BABB160@gmx.de> X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Complaints-To: abuse@demon.net X-Mail2News-Path: news.demon.net!mulga.cs.mu.oz.au X-Trace: mail2news.demon.co.uk 959563442 mail2news:25055 mail2news mail2news.demon.co.uk Organization: Southfield Microcomputer SS X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) MIME-Version: 1.0 Reply-To: Francis Glassborow Newsgroups: comp.std.c++ In article <392E5925.6BABB160@gmx.de>, Ole Reinartz writes >AFAIK in that special case you dont even have to define it for the linker >somewhere, because it is a constant. Because it will never change it doesnt >have to have a fixed location. The compiler is even allowed to optimize it >to a literal constant NO, it is only allowed to do this if it can prove that you never use the address of the storage. The following code is perfectly legitimate: int const i = 3; int const * i_ptr = &i; The compiler can only optimise away the storage if nothing in the program will detect this. Of course the compiler can optimise all uses of the value but that is not the same thing as not providing storage. As I wrote before, it would take a very meticulous compiler to complain that you had not defined the storage if you never actually used the address of such storage. If, in the case in point, you make the static const data private it is relatively easy for the compiler to determine that the address is not used, but if you assume that public static const data is fine, you just shot the optimiser. >(like it would do when you would #define m_a 1). Still >the type savety remains. >Also I think (didnt look it up in the standard though) that it works for all >the builtin types. You really should check the standard. A special rule was allowed for static const integer values because such values are often wanted as compile time constants (e.g. for an array size). enums were being used for named integer literals before this change was made. Francis Glassborow Association of C & C++ Users 64 Southfield Rd Oxford OX4 1PA +44(0)1865 246490 All opinions are mine and do not represent those of any organisation --- [ 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 ]