220 11525 article Path: news.gmane.org!not-for-mail From: Alex Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Add support for move-only types in std::priority_queue Date: Thu, 19 Jun 2014 11:36:27 +0300 Lines: 127 Approved: news@gmane.org Message-ID: References: <2fff5775-3cb1-433f-b01f-8018a65eec82@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=047d7b2e54b8d46de304fc2c453a X-Trace: ger.gmane.org 1403166996 15242 80.91.229.3 (19 Jun 2014 08:36:36 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 19 Jun 2014 08:36:36 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDOZJQ42YMARBC6CRKOQKGQEFVTHYXQ@isocpp.org Thu Jun 19 10:36:29 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 1WxXpd-0003QA-1g for gclcip-std-proposals@m.gmane.org; Thu, 19 Jun 2014 10:36:29 +0200 Original-Received: by mail-ig0-f198.google.com with SMTP id h3sf7301753igd.9 for ; Thu, 19 Jun 2014 01:36:28 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type; bh=LGOXSZNtNKJ95hhPF11NEpGyXHnH1fq+4aygvnGlVqo=; b=mwo5V+OXQqRfIv2XvrHhVD4st3KTeSGEt4Fv5tblv3NhdJA/27RzZbWU35dXDdKtv6 7Uypg5jC6/qfNv7Ctn9uSUaEqu01YTLQgLJ74ADb9vD9z30ye24mSbjUFj7wb3e83H6E I7VYOQgtMoPLlTkccl3vZb0oADPve8Cu8f4jIWVt+/8y0MploISQN6o4k5qRTZ05LFaL 0zcM9CchTeSgh+EO1kQLzHooUK3yBehNQ+hkaV2uchZTcQ1vIeqIfRibviJf94o0hq01 IuEPuwzJQIAjVq2RyT+oo0Jbf4D4AYxgmNHB0FHYD68BH2zNzXgpywVBJT2V8GzUEcea IhRg== X-Gm-Message-State: ALoCoQkHGpmFxRVDfET1vKxAl8wbeNOBu6ynDegPdTdDDbUte/Ad9D3xam9c8ZqpYs/LKAuwBwRz X-Received: by 10.182.128.166 with SMTP id np6mr1850426obb.16.1403166987978; Thu, 19 Jun 2014 01:36:27 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.40.74 with SMTP id w68ls466624qgw.53.gmail; Thu, 19 Jun 2014 01:36:27 -0700 (PDT) X-Received: by 10.58.208.228 with SMTP id mh4mr2889754vec.22.1403166987322; Thu, 19 Jun 2014 01:36:27 -0700 (PDT) Original-Received: from mail-vc0-x231.google.com (mail-vc0-x231.google.com [2607:f8b0:400c:c03::231]) by mx.google.com with ESMTPS id ht8si2041235vdb.61.2014.06.19.01.36.27 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 19 Jun 2014 01:36:27 -0700 (PDT) Received-SPF: pass (google.com: domain of alex.shtf@gmail.com designates 2607:f8b0:400c:c03::231 as permitted sender) client-ip=2607:f8b0:400c:c03::231; Original-Received: by mail-vc0-f177.google.com with SMTP id ij19so1910191vcb.36 for ; Thu, 19 Jun 2014 01:36:27 -0700 (PDT) X-Received: by 10.58.122.138 with SMTP id ls10mr2918808veb.13.1403166987150; Thu, 19 Jun 2014 01:36:27 -0700 (PDT) Original-Received: by 10.58.199.81 with HTTP; Thu, 19 Jun 2014 01:36:27 -0700 (PDT) In-Reply-To: X-Original-Sender: alex.shtf@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of alex.shtf@gmail.com designates 2607:f8b0:400c:c03::231 as permitted sender) smtp.mail=alex.shtf@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:11525 Archived-At: --047d7b2e54b8d46de304fc2c453a Content-Type: text/plain; charset=UTF-8 You mean that the pop_back() of the adapted container throws? I believe that the item is lost. But I believe that priority_queue cannot promise much anyway when exceptions are thrown. For example, what happens if the comparison function throws? The heap-order is not preserved and the user cannot rely on the contents of the priority_queue. On Thu, Jun 19, 2014 at 10:49 AM, Nevin Liber wrote: > On 19 June 2014 09:46, wrote: > >> Currently there is no clean way use move-only types in >> std::priority_queue. The top() function returns a const-reference and the >> pop() function does not return anything. >> I suggest adding a function, extract_top() that is equivalent to pop() >> except that it also returns the element that was at the top. >> > > What should happen if an exception is thrown? > -- > Nevin ":-)" Liber (847) 691-1404 > > -- > > --- > You received this message because you are subscribed to a topic in the > Google Groups "ISO C++ Standard - Future Proposals" group. > To unsubscribe from this topic, visit > https://groups.google.com/a/isocpp.org/d/topic/std-proposals/AQ2bJxtT_4g/unsubscribe > . > To unsubscribe from this group and all its topics, 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/. > -- --- 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/. --047d7b2e54b8d46de304fc2c453a Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
You mean that the pop_back() of the adapted container throws? I= believe that the item is lost.
But I believe that priority_queue cannot= promise much anyway when exceptions are thrown. For example, what happens = if the comparison function throws? The heap-order is not preserved and the = user cannot rely on the contents of the priority_queue.


O= n Thu, Jun 19, 2014 at 10:49 AM, Nevin Liber <nevin@eviloverlord.com= > wrote:
On 19 June = 2014 09:46, <alex.shtf@gmail.com> wrote:
Currently there is no clean way use move-only types in std= ::priority_queue. The top() function returns a const-reference and the pop(= ) function does not return anything.
I suggest adding a function, extrac= t_top() that is equivalent to pop() except that it also returns the element= that was at the top.

What should happen if an excep= tion is thrown?
-= -
=C2=A0Nevin ":-)" Liber=C2=A0 <mailto:nevin@eviloverlord.com>=C2= =A0 (847) 691-1404

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