220 16803 <54F94414.10909@gmail.com> article Path: news.gmane.org!not-for-mail From: Pavel Kretov Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Optimizing shutdown time by disabling global destructors Date: Fri, 06 Mar 2015 09:07:16 +0300 Lines: 58 Approved: news@gmane.org Message-ID: <54F94414.10909@gmail.com> References: <2205e402-724e-4415-a738-66a04c40f7c7@isocpp.org> <54F8653E.2050004@gmail.com> <768f81bc-027e-451a-968e-9f07f544882a@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1425622054 5439 80.91.229.3 (6 Mar 2015 06:07:34 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 6 Mar 2015 06:07:34 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCKZ764MQENRBGMI4WTQKGQE4I7D2EQ@isocpp.org Fri Mar 06 07:07:30 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wi0-f198.google.com ([209.85.212.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YTlPy-0004tx-JL for gclcip-std-proposals@m.gmane.org; Fri, 06 Mar 2015 07:07:26 +0100 Original-Received: by wivz2 with SMTP id z2sf243119wiv.1 for ; Thu, 05 Mar 2015 22:07:26 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :subject:references:in-reply-to:content-type :content-transfer-encoding:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=N81pNlK8XgE/yIk8cBNuQ0ApbPABXDTiDGOVwY1cJTM=; b=iz+4WS5V3aKFO/MEId4rai8Wpx5jwhjPqB+gXmH3RIUkrrjlwuK9hYphnDZmM5dJjb hL9EE0gkTTkWGg9ufDFFR4TDs1WEgnfKjYRxVpOGOMfx7QZBOtMPrNuU2Wfeu2OFv5VS j2JSqudXFcVH1wLRlOzugt1myXRapdGjGYkdZY1+5pxi4LVcJa+mcJgq+0tmKOxMYMC4 BDOyBlKffgyur78pIMBB3hit2qDhtyw6bO5EvysBQlyMELpyVVTnl+PNxRRZVX35Az/P gLghdDqqNuFWnACiCcjSsGzTHlum/FY2FPu8yp5UJ8hHFjSywajNZRD7z3XLbbReSqIT X-Gm-Message-State: ALoCoQk0HA3zl3wxXjlzRe40Qseleyj+CxuoZM+rTZBTn/lS2tuVQ+SwF1GYjajuh6Qxmvik713s X-Received: by 10.180.182.81 with SMTP id ec17mr2486474wic.0.1425622046040; Thu, 05 Mar 2015 22:07:26 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.152.8.134 with SMTP id r6ls40626laa.59.gmail; Thu, 05 Mar 2015 22:07:20 -0800 (PST) X-Received: by 10.112.154.234 with SMTP id vr10mr10954556lbb.115.1425622040874; Thu, 05 Mar 2015 22:07:20 -0800 (PST) Original-Received: from mail-lb0-x231.google.com (mail-lb0-x231.google.com. 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[91.219.160.129]) by mx.google.com with ESMTPSA id dk5sm1612206lad.41.2015.03.05.22.07.17 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 05 Mar 2015 22:07:19 -0800 (PST) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 In-Reply-To: <768f81bc-027e-451a-968e-9f07f544882a@isocpp.org> X-Original-Sender: firegurafiku@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of firegurafiku@gmail.com designates 2a00:1450:4010:c04::231 as permitted sender) smtp.mail=firegurafiku@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=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:16803 Archived-At: > It can break program correctness if you are relying on nodestroy for > correct global destruction order. If the attribute is optional, the featu= re > cannot be used for this purpose. User must not rely on an attribute as well as, for example, they cannot=20 rely on an "inline" keyword. User must treat your [[nodestroy]] the same=20 way and write their code to be correct regardless of it. > The only difference you're adding here is you're specifying nodestroy as = an > attribute of a type instead of a variable. That is a huge difference. Suppose you've marked an variable with the=20 attribute, like that: Application [[nodestroy]] application; This object can internally hold a whole hierarchy of pointers to other=20 objects (forms, widgets, images loaded into memory), and some of them=20 may probably REALLY need non-trivial destruction (for example, a file=20 stream implicitly created deeply inside the GUI framework's internal=20 objects). User cannot be sure if it is safe for him to use [[nodestroy]]=20 on that variable. Moreover, destructors can also be virtual and user=20 cannot be sure if any possible subclass is safe to skip destructor. So, [[nodestroy]] attribute on variable is more dangerous when it=20 erroneously used, then it is ignored by the compiler. Sticking it to=20 class declaration may serve as a hint for the compiler do solve the=20 problem by itself in the most sane way. Also, you can achieve the desired effect already without having to=20 introduce any changes to the standard. Like that: class Singleton { static Singleton& get() { // NB: Memory leak here is intentional and okay. // Dear maintainer, don't kill me plz. static Singleton* s =3D new Singleton(); return *s; } }; =E2=80=94=E2=80=94=E2=80=94 Pavel Kretov. --=20 ---=20 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 e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. .