220 33482 <8c0ebca3-0dbd-444b-b0b0-845eca5b0de7@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: P0329R0 falls short for designated initialisers Date: Mon, 31 Jul 2017 20:13:09 -0700 (PDT) Lines: 105 Approved: news@gmane.org Message-ID: <8c0ebca3-0dbd-444b-b0b0-845eca5b0de7@isocpp.org> References: <4892340.tBhI7hZKOg@tjmaciei-mobl1> <2091187.OFx8EjqvIG@tjmaciei-mobl1> <54c48d0d-cc17-429d-bc59-5dffa1bb8846@isocpp.org> <3975136.UunVSsvxqs@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_76_1858211338.1501557189300" X-Trace: blaine.gmane.org 1501557193 5948 195.159.176.226 (1 Aug 2017 03:13:13 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 1 Aug 2017 03:13:13 +0000 (UTC) Cc: zy@miator.net To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCEKFTV6ZUMBBRXD77FQKGQEBAJCUSQ@isocpp.org Tue Aug 01 05:13:08 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f199.google.com ([209.85.161.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dcNcH-00013s-LX for gclcip-std-proposals@m.gmane.org; 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Mon, 31 Jul 2017 20:13:11 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.180.215 with SMTP id d206ls9596915iof.31.gmail; Mon, 31 Jul 2017 20:13:09 -0700 (PDT) X-Received: by 10.31.142.14 with SMTP id q14mr42933vkd.19.1501557189833; Mon, 31 Jul 2017 20:13:09 -0700 (PDT) In-Reply-To: X-Original-Sender: jmckesson@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:33482 Archived-At: ------=_Part_76_1858211338.1501557189300 Content-Type: multipart/alternative; boundary="----=_Part_77_279750495.1501557189300" ------=_Part_77_279750495.1501557189300 Content-Type: text/plain; charset="UTF-8" On Monday, July 31, 2017 at 10:28:55 PM UTC-4, Zhihao Yuan wrote: > > On Mon, Jul 31, 2017 at 2:42 PM, Thiago Macieira > wrote: > > It definitely isn't for non-trivial types, but I don't > > know if it should be allowed for trivial ones. > > > > [...] > > > > Either way, that doesn't stop us from allowing: > > > > Agg a { .y = 5, .x = 5 }; > > > > I've stated my concern with dividing the feature > into trivial types only and those not -- it brings > damage when the library evolves. > > However, I feel it's more acceptable if we allocate > a syntax to let people opt-in. I mean, what if > such a discrimination happens only when a > user asks for it by using the = { ... } initializer > (copy-init syntax)? Right, because the thing we most need to do is make "uniform initialization" *less uniform*. No, having copy-list-initialization work (almost) exactly like direct-list-initialization is one of the best aspects of list-initialization. We should not undo that lightly. If unordered designated initializers are dangerous enough to need their own special syntax, then they're too dangerous for C++. -- 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/8c0ebca3-0dbd-444b-b0b0-845eca5b0de7%40isocpp.org. ------=_Part_77_279750495.1501557189300 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Monday, July 31, 2017 at 10:28:55 PM UTC-4, Zhihao Yuan= wrote:
On Mon, Jul 31, 2017 at= 2:42 PM, Thiago Macieira <thi...@macieira.org> wrote:
> It definitely isn't for non-trivial types, but I don't
> know if it should be allowed for trivial ones.
>
> [...]
>
> Either way, that doesn't stop us from allowing:
>
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 Agg a { .y =3D 5, .x =3D 5 };
>

I've stated my concern with dividing the feature
into trivial types only and those not -- it brings
damage when the library evolves.

However, I feel it's more acceptable if we allocate
a syntax to let people opt-in. =C2=A0I mean, what if
such a discrimination happens only when a
user asks for it by using the =3D { ... } initializer
(copy-init syntax)?

Right, because the thing we mo= st need to do is make "uniform initialization" less uniform.

No, having copy-list-initialization work (almost) exactly like di= rect-list-initialization is one of the best aspects of list-initialization.= We should not undo that lightly.

If unordered designated initialize= rs are dangerous enough to need their own special syntax, then they're = too dangerous for C++.

--
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.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/8c0ebca3-0dbd-444b-b0b0-845eca5b0de7= %40isocpp.org.
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