220 37586 article Path: news.gmane.org!.POSTED!not-for-mail From: Nicolas Lesser Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: add the metafunction scope Date: Sun, 01 Apr 2018 22:58:57 +0000 Lines: 90 Approved: news@gmane.org Message-ID: References: <5e47cc81-4834-4a68-8925-717fb2ec8612@isocpp.org> <20180330054757.GA2396@noemi> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="000000000000baf6ff0568d16b13" X-Trace: blaine.gmane.org 1522623432 21372 195.159.176.226 (1 Apr 2018 22:57:12 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 1 Apr 2018 22:57:12 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDXKNLEUTADRBPOIQXLAKGQEQTVUWLY@isocpp.org Mon Apr 02 00:57:08 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oi0-f70.google.com ([209.85.218.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1f2luN-0005NU-OZ for gclcip-std-proposals@m.gmane.org; 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[209.85.220.41]) by mx.google.com with SMTPS id e84-v6sor5224111oig.241.2018.04.01.15.59.08 for (Google Transport Security); Sun, 01 Apr 2018 15:59:08 -0700 (PDT) Received-SPF: pass (google.com: domain of blitzrakete@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 2002:aca:2804:: with SMTP id 4-v6mr4223260oix.74.1522623548420; Sun, 01 Apr 2018 15:59:08 -0700 (PDT) In-Reply-To: X-Original-Sender: blitzrakete@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=KU3Bkt0E; spf=pass (google.com: domain of blitzrakete@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=blitzrakete@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com 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:37586 Archived-At: --000000000000baf6ff0568d16b13 Content-Type: text/plain; charset="UTF-8" I'm not an experienced compiler writer but wouldn't that actually be a performance pessimization? Because now the compiler has to delete objects instead of just keeping them around, or is the cost of finding instantiations more expensive? Do you have an implementation? I really think that you'll need actual measurements to make this work, as it's not trivial: Keeping instantiations around is a completely implementation defined thing not even mentioned by the standard at any point AFAIK. On Fri, Mar 30, 2018, 4:55 PM wrote: > Testing... > > -- > 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/b8de3daf-019d-40e2-a039-082ca9c61c96%40isocpp.org > > . > -- 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/CALmDwq1zuF95AfUZ9Mx23af%2BEFk-XaR7TwR01pc0tS_akgfeew%40mail.gmail.com. --000000000000baf6ff0568d16b13 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
I'm not an experienced compiler writer but wouldn'= ;t that actually be a performance pessimization? Because now the compiler h= as to delete objects instead of just keeping them around, or is the cost of= finding instantiations more expensive?

Do you have an implementation? I really think that you'll nee= d actual measurements to make this work, as it's not trivial: Keeping i= nstantiations around is a completely implementation defined thing not even = mentioned by the standard at any point AFAIK.

On Fri, Mar 30, 2018, 4:55 PM <liweif= riends@gmail.com> wrote:
Tes= ting...

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