220 28528 <073a7698-1388-4858-b6fa-b2b62a4fb6f1@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Greg Marr Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: A plea to reconsider adding Structured Bindings to language Date: Wed, 5 Oct 2016 06:49:33 -0700 (PDT) Lines: 97 Approved: news@gmane.org Message-ID: <073a7698-1388-4858-b6fa-b2b62a4fb6f1@isocpp.org> References: <201610051238.17863.marc.mutz@kdab.com> <201610051300.02280.marc.mutz@kdab.com> <201610051411.30312.marc.mutz@kdab.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_4413_768177591.1475675373607" X-Trace: blaine.gmane.org 1475675397 25305 195.159.176.226 (5 Oct 2016 13:49:57 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 5 Oct 2016 13:49:57 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDEZH3XFPIIO5COUX4CRUBCZHXJFI@isocpp.org Wed Oct 05 15:49:52 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk0-f198.google.com ([209.85.220.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1brmZn-0004GK-Cg for gclcip-std-proposals@m.gmane.org; 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Wed, 05 Oct 2016 06:49:41 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.66.11 with SMTP id i11ls386237itb.12.gmail; Wed, 05 Oct 2016 06:49:34 -0700 (PDT) X-Received: by 10.36.117.6 with SMTP id y6mr666170itc.7.1475675374279; Wed, 05 Oct 2016 06:49:34 -0700 (PDT) In-Reply-To: <201610051411.30312.marc.mutz@kdab.com> X-Original-Sender: gregmmarr@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: 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:28528 Archived-At: ------=_Part_4413_768177591.1475675373607 Content-Type: multipart/alternative; boundary="----=_Part_4414_191914130.1475675373607" ------=_Part_4414_191914130.1475675373607 Content-Type: text/plain; charset=UTF-8 On Wednesday, October 5, 2016 at 8:09:43 AM UTC-4, Marc Mutz wrote: > > On Wednesday 05 October 2016 13:40:20 Domen Vrankar wrote: > > So you're saying that returning a structure with error status and result > or > > multiple results of which you only need one or two (reason being for eg. > > cheaper to return all at once - due to for e.g. web service call or > complex > > processing - than request one by one on need to basis) you would still > > prefer dragging the entire structure around giving the feeling that your > > code has more dependencies than it actually does? > > One of us is not underatanding SB correctly, or I don't understand you. SB > stores the whole struct, too, it just defines local aliases to the member > of > the struct (or tuple, or pair, or ...). > Only if you say that you want references, using "auto &" or "auto &&". If you use "auto", you just get copies. - If the *assignment-expression* is a prvalue, *e* is an xvalue that designates a temporary object copy-initialized from the *assignment-expression*. The lifetime of the temporary ends immediately after the last variable declaration (see below) if no & follows the *decl-specifier-seq* in the decomposition declaration, and is extended as usual (12.2 [class.temporary] otherwise. -- 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/073a7698-1388-4858-b6fa-b2b62a4fb6f1%40isocpp.org. ------=_Part_4414_191914130.1475675373607 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Wednesday, October 5, 2016 at 8:09:43 AM UTC-4, Marc Mu= tz wrote:
On Wednesday 05 Octob= er 2016 13:40:20 Domen Vrankar wrote:
> So you're saying that returning a structure with error status = and result or
> multiple results of which you only need one or two (reason being f= or eg.
> cheaper to return all at once - due to for e.g. web service call o= r complex
> processing - than request one by one on need to basis) you would s= till
> prefer dragging the entire structure around giving the feeling tha= t your
> code has more dependencies than it actually does?

One of us= is not underatanding SB correctly, or I don't understand you. SB=20
stores the whole struct, too, it just defines local aliases to the memb= er of=20
the struct (or tuple, or pair, or ...).

Only if you say that you want referenc= es, using "auto &" or "auto &&". =C2=A0If y= ou use "auto", you just get copies.

  • If the=C2=A0assignment-expression=C2=A0is a prva= lue,=C2=A0e=C2=A0is an xvalue that designates a temporary object c= opy-initialized from the=C2=A0assignment-expression. The lifetime = of the temporary ends immediately after the last variable declaration (see = below) if no=C2=A0&=C2=A0follows the=C2=A0decl-specifi= er-seq=C2=A0in the decomposition declaration, and is extended as usual= (12.2 [class.temporary] otherwise.

--
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To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/073a7698-1388-4858-b6fa-b2b62a4fb6f1= %40isocpp.org.
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