220 26527 <222b413d-87f4-4ad6-99a3-9090e5f03289@isocpp.org> article Path: news.gmane.org!not-for-mail From: "'Walt Karas' via ISO C++ Standard - Future Proposals" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Proposing: a library header providing a flexible, portable, performant structure bit field facility Date: Sat, 2 Jul 2016 08:54:58 -0700 (PDT) Lines: 126 Approved: news@gmane.org Message-ID: <222b413d-87f4-4ad6-99a3-9090e5f03289@isocpp.org> References: <7d635ed8-e567-4515-b51b-137e46b2b203@isocpp.org> <43fedeb4-bd0c-4ea9-9d34-13e4325c86fa@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_288_182376300.1467474898745" X-Trace: ger.gmane.org 1467474902 27584 80.91.229.3 (2 Jul 2016 15:55:02 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 2 Jul 2016 15:55:02 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDFLZXWOVYIBBU6H365QKGQEEX2T5AA@isocpp.org Sat Jul 02 17:55:02 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ob0-f200.google.com ([209.85.214.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bJNG1-0006iz-Lr for gclcip-std-proposals@m.gmane.org; Sat, 02 Jul 2016 17:55:01 +0200 Original-Received: by mail-ob0-f200.google.com with SMTP id hx8sf292286362obb.0 for ; Sat, 02 Jul 2016 08:55:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=87xrYN/AdQTEsHKCT/4oUgabX+yV3wSNfCYqV9FE/PI=; b=bZitjeZwV30cUG+t/du8HbL+Uqf9sGIJ3+6eLjDjerOPzQ4cOZF+Fya8MA4oODsQT6 gZQaSP9VigIVf7hkFNmr003hi865ZmJ9kW5SHMB94dgsQZiLZCxnDZk1iBDfVko8mrDn c+PyrpKVGKY5bum8HVSiGoCbpL3EZ1ntjfbcJ256C1bhdOCjgP/o/gwsfjWrvg8HkSff AYHkjbG9/srUKsEB0c11Q/A3X6BqMXceaG6EDLr/LpiFv8ok1BKHPCm9CWmmSdZiUq4e ffD63SWi2lzHKitw4g+kikUGIg9Gzd8NNTV9iVR6+XwSGYF0+ASFNeiMpkeNdsNcOdnp Yysg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=87xrYN/AdQTEsHKCT/4oUgabX+yV3wSNfCYqV9FE/PI=; b=b+NeL66ov+qmQxXJHMI88KKqUBA+Osvl03aIGeZxA2/iuZJx58GsdON/ZNDOfOWw/G Yg42ZDBRXJNDO02Xirl4f7934zruFLF2BNIvUaIBenLHv7nztODr5BsiYWb1opDtCsOg hdA3ROo/dusX/MQyYDzCNRhtp4Sok97a/K7HdHjkQb7so/iWFNterCrKHVrxYikQlHo2 2PAmA2sQnr74n4YGA9cmkl6rUrqoD0KDR8HFKo7LD34kXJOzHKFa0zZXGqGnnfTtx6EC Oti2I+nhviiwEDi291Dm+IzXy46gOeApOj3XH+xeAzuqav6VpnoWgj2Vpqb1g3WsogLs yAuw== X-Gm-Message-State: ALyK8tK8q49V3NVSgcVuj+xxkgLtT8Xx6Mkwtu2DnxL+PpiFI9aAQ5XLtG2Gl60pI1427g== X-Received: by 10.157.45.227 with SMTP id g90mr21785147otb.1.1467474900678; Sat, 02 Jul 2016 08:55:00 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.227.196 with SMTP id d187ls257585ith.5.gmail; Sat, 02 Jul 2016 08:54:59 -0700 (PDT) X-Received: by 10.36.91.149 with SMTP id g143mr149057itb.7.1467474899659; Sat, 02 Jul 2016 08:54:59 -0700 (PDT) In-Reply-To: <43fedeb4-bd0c-4ea9-9d34-13e4325c86fa@isocpp.org> X-Original-Sender: wkaras@yahoo.com X-Original-From: Walt Karas Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:26527 Archived-At: ------=_Part_288_182376300.1467474898745 Content-Type: multipart/alternative; boundary="----=_Part_289_1396058179.1467474898745" ------=_Part_289_1396058179.1467474898745 Content-Type: text/plain; charset=UTF-8 On Friday, July 1, 2016 at 11:46:00 PM UTC-4, Walt Karas wrote: > > > > On Friday, July 1, 2016 at 10:57:35 AM UTC-4, Walt Karas wrote: >> >> This prototype could be used as a starting point: >> >> https://github.com/wkaras/C-plus-plus-library-bit-fields >> >> I think the use of macros and reinterpret_cast could be eliminated with >> some tweaks to member pointers in the base language: >> >> o Allow static_cast(mp) where mp is a pointer to a data member >> of a Standard Layout Class. >> >> o Eliminate the need for boilerplate & and class name prefix when the >> context implies them. So: >> >> int Cls::*p = &x.i; >> > > Typo, replace with: > > int Cls::*p = &Cls::i; > > > >> >> could be written simply as: >> >> int Cls::*p = i; >> >> o Allow member pointers to members of members and base classes. >> Possible syntax (showing boiler plate): >> >> mp1 = &Cls::x.y; // member of member >> mp2 = &Cls::Base; // base >> mp3 = &Cls::Base::SubBase; // sub-base >> > My thinking is that, with these changes, bit field structure use could look something like: std::bitf::mem x; x[u.v] = 57; // v a member of u, a member of Format, which is a bit field format structure Or, with the dot operator overloading proposal, accessing a bit field could look the same as it currently does. -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/222b413d-87f4-4ad6-99a3-9090e5f03289%40isocpp.org. ------=_Part_289_1396058179.1467474898745 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Friday, July 1, 2016 at 11:46:00 PM UTC-4, Walt Karas w= rote:


= On Friday, July 1, 2016 at 10:57:35 AM UTC-4, Walt Karas wrote:
This prototype could be used a= s a starting point:


I t= hink the use of macros and reinterpret_cast could be eliminated with some t= weaks to member pointers in the base language:

o = =C2=A0Allow static_cast<size_t>(mp) where mp is a pointer to a data m= ember of a Standard Layout Class.

o =C2=A0Eliminat= e the need for boilerplate & and class name prefix when the context imp= lies them. =C2=A0So:

int Cls::*p =3D &x.i;

Typo, replace with:

=
int Cls::*p =3D &Cls::i;

=C2=A0

<= div>could be written simply as:

int Cls::*p =3D i;=

o =C2=A0Allow member pointers to members of membe= rs and base classes. =C2=A0Possible syntax (showing boiler plate):

mp1 =3D &Cls::x.y; // member of member
mp2 = =3D &Cls::Base; // base
mp3 =3D &Cls::Base::SubBase; // s= ub-base

= My thinking is that, with these changes, bit field structure use could look= something like:

std::bitf<Traits, Format>::= mem x;
x[u.v] =3D 57; // v a member of u, a member of Format, whi= ch is a bit field format structure

Or, with the do= t operator overloading proposal, accessing a bit field could look the same = as it currently does.

--
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To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
To post to this group, send email to std-proposals@isocpp.org.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/222b413d-87f4-4ad6-99a3-9090e5f03289= %40isocpp.org.
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