220 13897 <7c04a6d6-c6df-4ef2-8cfc-0ca3606db9e6@isocpp.org> article Path: news.gmane.org!not-for-mail From: Michael Bruck Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Proposal for a delete expression for local variables Date: Wed, 15 Oct 2014 07:58:19 -0700 (PDT) Lines: 100 Approved: news@gmane.org Message-ID: <7c04a6d6-c6df-4ef2-8cfc-0ca3606db9e6@isocpp.org> References: <16366a2f-03b6-4e2a-9007-7819afe28460@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_527_857056717.1413385099380" X-Trace: ger.gmane.org 1413385108 4966 80.91.229.3 (15 Oct 2014 14:58:28 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 15 Oct 2014 14:58:28 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDO2X46R4AKRBC4X7KQQKGQEX6BNNJQ@isocpp.org Wed Oct 15 16:58:21 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f198.google.com ([209.85.213.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XeQ1t-0004pa-BV for gclcip-std-proposals@m.gmane.org; Wed, 15 Oct 2014 16:58:21 +0200 Original-Received: by mail-ig0-f198.google.com with SMTP id a13sf6338288igq.9 for ; Wed, 15 Oct 2014 07:58:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe :content-type; bh=w6NYrdVc7j7Po0T3xStAraYWN8l0qafceK8m3MKztxY=; b=q8ndUFZHnuiSi7eGTLHdCVW3WsR+VZKWalstOeXcOm74L3rf6DoG1bASkKK5jXmpnr Zbx+64Vvf+j/ONgBfjS1SDV56DqEbtEy8G18X3PwA5EhYcywu46oeXH0wWNXxAByntzN QGKxCPTw2GTdsEJnOk9XLNNv0ekLLJC8Pci3XMAjg9hqSTjBaKfVYdcUl4EOhDACf+pW OyaOob5loSIg6beSkOUaozd0f3ZfYg4a5z02KcOUujkthEL3EqfwvBh1UMFL9qLzmJVv YZqeca99n5oDpI+dlnWEc4NcplrHg5kQW0Y4g3riwQeslmplxwLwR0aFDiBoFoZ/CjLo xJ4Q== 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:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type; bh=w6NYrdVc7j7Po0T3xStAraYWN8l0qafceK8m3MKztxY=; b=UU4Jg4yoJnnJfHThgsnhzQq413m+XO81lGHnylRNuV1/kC+JXC767PEf5gAw0GCl/t zICXVnwdPG8kjnslKE1++XeJaOiw81Q3QXmeE54/m9utHSdC6q6cvXUP4S1OBEC/hF26 Y58/JSkGOOejUAZhkdy1ToQu+MR+GX4aXI2m6YndOoTVzkgHoo1ceKBGDLG146m+sbrC cuD66pHlVfExlufLjNx5Kjgsuyu7e03Lhu4IGBrCsALcoE3iD/D70yEt1MYOm3sPwxum yXgmJrAkGb/+HgD74a5PPpIIXjJcqVVehw8qoW0fAGSW2ClQUN8GJd496BG2MM7+b05X OC/g== X-Gm-Message-State: ALoCoQnTGpB5h/XuJWr28cctCv0eJd0FwkIl2EDsb7zrV3C/ukkRxO3DPF/p3rMpff6bentCKy3o X-Received: by 10.182.27.206 with SMTP id v14mr8368916obg.39.1413385100309; Wed, 15 Oct 2014 07:58:20 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.49.99 with SMTP id p90ls287788qga.29.gmail; Wed, 15 Oct 2014 07:58:19 -0700 (PDT) X-Received: by 10.140.21.49 with SMTP id 46mr12534qgk.30.1413385099759; Wed, 15 Oct 2014 07:58:19 -0700 (PDT) In-Reply-To: X-Original-Sender: bruck.michael@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:13897 Archived-At: ------=_Part_527_857056717.1413385099380 Content-Type: text/plain; charset=UTF-8 On Wednesday, October 15, 2014 1:55:59 PM UTC+2, David Krauss wrote: > > > > On Wednesday, October 15, 2014 6:06:53 PM UTC+8, Andrew Tomazos wrote: >> >> Sorry, I should have actually read your proposal - specifically I think: >> >> { >> >> auto file = file_open_rlock("data_snippet"); >> >> auto blob = file.fetch_all(); >> >> file.close(); >> > > Not only is it more readable, it's more correct. Relying on destructors > for side effects demands that they ignore any failures. Explicitly flushing > and closing a file or a connection before it goes out of scope gives a > confirmation of success that implicit destructor cleanup does not. (At > least, that can't safely happen until uncaught_exception gets fixed.) > > Likewise, it's cleaner if a destructor can treat an open state as a > failure, and avoid flushing or such side effects for the sake of safety > over convenience. > If I understand it correctly the destructor exception issue could be fixed by the time this extension is added? -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. ------=_Part_527_857056717.1413385099380 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Wednesday, October 15, 2014 1:55:59 PM UTC+2, D= avid Krauss wrote:


On Wednesday, October 15, 2014 6:06:53 PM UTC+8, Andrew Tomazo= s wrote:
Sorry, I s= hould have actually read your proposal - specifically I think:

{

aut= o file =3D file_open_rlock("data_snippet");

auto blob =3D file.fetch_all();

file.close();

=
Not only is it more readable, it's more correct. Relying on destructors= for side effects demands that they ignore any failures. Explicitly flushin= g and closing a file or a connection before it goes out of scope gives a co= nfirmation of success that implicit destructor cleanup does not. (At least,= that can't safely happen until uncaught_exception gets fixed.)

Like= wise, it's cleaner if a destructor can treat an open state as a failure, an= d avoid flushing or such side effects for the sake of safety over convenien= ce.

If I understand it corr= ectly the destructor exception issue could be fixed by the time this extens= ion is added?

--

---
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
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.
Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/<= /a>.
------=_Part_527_857056717.1413385099380-- .