220 20514 <37C94EDD-51ED-4A8B-880F-EA9CFEC13A36@gmail.com> article Path: news.gmane.org!not-for-mail From: David Krauss Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Draft D0065: Movable initializer lists, rev. 2 Date: Sun, 20 Sep 2015 13:02:41 +0800 Lines: 159 Approved: news@gmane.org Message-ID: <37C94EDD-51ED-4A8B-880F-EA9CFEC13A36@gmail.com> References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) Content-Type: multipart/alternative; boundary="Apple-Mail=_E954A457-5693-4844-8C91-36033AC67ECE" X-Trace: ger.gmane.org 1442725381 19980 80.91.229.3 (20 Sep 2015 05:03:01 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 20 Sep 2015 05:03:01 +0000 (UTC) Cc: ISO C++ Standard - Future Proposals To: Rodrigo Original-X-From: std-proposals+bncBCW25A7E3QCRB7H37CXQKGQE2543TZI@isocpp.org Sun Sep 20 07:02:57 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f72.google.com ([209.85.213.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZdWm7-00066V-U4 for gclcip-std-proposals@m.gmane.org; Sun, 20 Sep 2015 07:02:56 +0200 Original-Received: by vkgd64 with SMTP id d64sf132777209vkg.2 for ; Sat, 19 Sep 2015 22:02:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:content-type:mime-version:subject:from :in-reply-to:date:cc:message-id:references:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=eApXTOGagJd2bBqb+SZYy0YZZDyE8gr5lHvmXlvgBL4=; b=QYAHjL5kxM4UQpzbfQzn06zxC0EFxroHWxagrv7TAmBQXFjxqlirQKZqzlygA5St0u 9BtnOMyw6rVPZUbKnN7YKWBTEGaKIrjH7DR5q60ENcP1rTEGrexVHS1AGZY3nPUBu42K ttqMMQsSvFMHSE0KKj8Fkj1cK8kwTQz64T5J4fZW9IWcxo+zr3HYJF6CNW3gDoHxflXH oH6LWvecWoyEzJb1frqW19Bq4x8FFMspUCH9IgR7Oc4eUyDi9C5USd0m4bh0UUqU/hEQ Pl0+1/PmJENUMks2h1Fa15fABMG5Li2bdtSWKGNytFM0yMcfVkAfayeG7VdiEUQ32P9x SKMA== X-Gm-Message-State: ALoCoQndjhq/GaPFVlw2gWPcG3nVypVuuAt1v2fAKGikfwnTweFh+CcTeAf29eSrzKn9OnDvG3nr X-Received: by 10.129.76.9 with SMTP id z9mr11404587ywa.35.1442725374350; Sat, 19 Sep 2015 22:02:54 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.4.5 with SMTP id g5ls572571igg.6.canary; Sat, 19 Sep 2015 22:02:52 -0700 (PDT) X-Received: by 10.50.23.80 with SMTP id k16mr5331310igf.62.1442725372615; Sat, 19 Sep 2015 22:02:52 -0700 (PDT) Original-Received: from mail-pa0-x235.google.com (mail-pa0-x235.google.com. [2607:f8b0:400e:c03::235]) by mx.google.com with ESMTPS id t70si13053482ioi.204.2015.09.19.22.02.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 19 Sep 2015 22:02:52 -0700 (PDT) Received-SPF: pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c03::235 as permitted sender) client-ip=2607:f8b0:400e:c03::235; Original-Received: by padhy16 with SMTP id hy16so86105411pad.1 for ; Sat, 19 Sep 2015 22:02:52 -0700 (PDT) X-Received: by 10.68.202.9 with SMTP id ke9mr16705136pbc.85.1442725372010; Sat, 19 Sep 2015 22:02:52 -0700 (PDT) Original-Received: from [172.20.10.2] ([121.54.44.88]) by smtp.gmail.com with ESMTPSA id qn5sm12295099pbc.74.2015.09.19.22.02.48 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 19 Sep 2015 22:02:51 -0700 (PDT) In-Reply-To: X-Mailer: Apple Mail (2.2104) X-Original-Sender: potswa@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c03::235 as permitted sender) smtp.mailfrom=potswa@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-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:20514 Archived-At: --Apple-Mail=_E954A457-5693-4844-8C91-36033AC67ECE Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 > On 2015=E2=80=9309=E2=80=9320, at 7:46 AM, Rodrigo w= rote: >=20 > Hi David, sorry for answering until now. No worries, you=E2=80=99re still the first. > The name "std::own_initializer_list" is probably not worse than the alter= natives ("mutable", "unique", etc), but I think it is too long anyway (and = I say this even though the name I originally proposed was longer...). The o= nly alternative I can suggest right now is "std::temporary_list". It could = mistakenly relate itself (by name) to the "std::get_temporary_buffer" funct= ion (and friend), but I like it by itself. The paper already mentions sequence_literal as an alternative, if we were s= tarting with a clean slate. Previously it was listed together with the othe= rs. I=E2=80=99ve re-added that bullet in the naming section, plus your sugg= estion. > While I was reading the part that says that ~std::own_initializer_list is= the responsible of destroying the elements, I had to go back and re-read t= he part that talks about std::own_initializer_list vs std::own_ini= tializer_list&& as an overload. Some code fragment like the follow= ing: >=20 > struct my_container { > my_container(std::initializer_list); > my_container(std::own_initializer_list); > //... > }; >=20 > is typical when teaching which are the most important constructors in the= implementation of a data structure. It could be good idea to add it, other= wise the explanation could be lost inside all the text (at first I understo= od that we had to use the && overload, but of course this is wrong). I=E2=80=99ve added an example of by-value and by-&& overloading. > I think I didn't understand the part about the "loop hoisting variant" of= the static storage optimization. Some time ago I was thinking about an opt= imization that initializes and leaves constexpr arguments of the initialize= r_list untouched and only overwrites those that change at runtime from use = to use. Probably it is similar to the one you mention, but I could be wrong= .. It=E2=80=99s along those lines. As far as I know (by hearsay) only EDG impl= ements this. The paper doesn=E2=80=99t go into depth except to mention that= it was considered and it shouldn=E2=80=99t present a problem. > In something much less important, the very first sentence of the paper ha= s too many commas! I would delete the one after "only=E2=80=9D. Done. > Cheers! Thanks! --=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/. --Apple-Mail=_E954A457-5693-4844-8C91-36033AC67ECE Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=UTF-8
On 2015=E2=80=9309= =E2=80=9320, at 7:46 AM, Rodrigo <rcc.dark@gmail.com> wrote:

=
Hi David, s= orry for answering until now.
<= /div>

No worries, you=E2= =80=99re still the first.

The name "std::own_initializer_lis= t" is probably not worse than the alternatives ("mutable", "unique", etc), = but I think it is too long anyway (and I say this even though the name I or= iginally proposed was longer...). The only alternative I can suggest right = now is "std::temporary_list". It could mistakenly relate itself (by name) t= o the "std::get_temporary_buffer" function (and friend), but I like it by i= tself.
=
The paper already mentions sequence_literal as an alternative, if we were starting = with a clean slate. Previously it was listed together with the others. I=E2= =80=99ve re-added that bullet in the naming section, plus your suggestion.<= /div>

While I was reading the part that says that ~std::own_initializer= _list is the responsible of destroying the elements, I had to go back and r= e-read the part that talks about std::own_initializer_list<my_type> v= s std::own_initializer_list<my_type>&& as an overload. Some c= ode fragment like the following:

struct = my_container {
   my_container(std::initializ= er_list<my_type>);
   my_container(std:= :own_initializer_list<my_type>);
   //...
};

=
is typical when teaching which are the most important= constructors in the implementation of a data structure. It could be good i= dea to add it, otherwise the explanation could be lost inside all the text = (at first I understood that we had to use the && overload, but of c= ourse this is wrong).

I=E2=80=99ve added an example of by-value and = by-&& overloading.
I think I didn't unders= tand the part about the "loop hoisting variant" of the static storage optim= ization. Some time ago I was thinking about an optimization that initialize= s and leaves constexpr arguments of the initializer_list untouched and only= overwrites those that change at runtime from use to use. Probably it is si= milar to the one you mention, but I could be wrong.

It=E2=80=99s along those lines. As far as I know (by hearsay) only ED= G implements this. The paper doesn=E2=80=99t go into depth except to mentio= n that it was considered and it shouldn=E2=80=99t present a problem.
<= br class=3D"">
In something much less = important, the very first sentence of the paper has too many commas! I woul= d delete the one after "only=E2=80=9D.

Done.

Cheers!
=

Thanks!

--

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