220 31170 <449d2b1f-5a52-428b-b5d8-54f7c47014bc@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: "T. C." Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Domains of specialized `vector` variance Date: Sun, 26 Feb 2017 09:06:17 -0800 (PST) Lines: 116 Approved: news@gmane.org Message-ID: <449d2b1f-5a52-428b-b5d8-54f7c47014bc@isocpp.org> References: <38052307-8ef9-4d41-b902-826f56630c10@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_647_354021713.1488128777349" X-Trace: blaine.gmane.org 1488128778 29122 195.159.176.226 (26 Feb 2017 17:06:18 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 26 Feb 2017 17:06:18 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCQ43G7NQIIRBCMWZTCQKGQEPCIEJYI@isocpp.org Sun Feb 26 18:06:13 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pf0-f197.google.com ([209.85.192.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1ci2Gy-00074P-TT for gclcip-std-proposals@m.gmane.org; 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Sun, 26 Feb 2017 09:06:18 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.36.230 with SMTP id z93ls10111246ota.44.gmail; Sun, 26 Feb 2017 09:06:17 -0800 (PST) X-Received: by 10.157.16.48 with SMTP id h45mr779681ote.10.1488128777809; Sun, 26 Feb 2017 09:06:17 -0800 (PST) In-Reply-To: X-Original-Sender: rs2740@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:31170 Archived-At: ------=_Part_647_354021713.1488128777349 Content-Type: multipart/alternative; boundary="----=_Part_648_1857871506.1488128777349" ------=_Part_648_1857871506.1488128777349 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Sunday, February 26, 2017 at 8:18:41 PM UTC+8, Daniel Kr=C3=BCgler wrote= : > > 2017-02-26 11:25 GMT+01:00 >:=20 > >> What are the other variances that people want?=20 > >=20 > > This could fix problem with `std::vector`, current vector would= =20 > be:=20 > > `omni_vector` and if you want "normal"=20 > behavior=20 > > you will use directly `omni_vector`.=20 > > It is very unlikely that this will happen, because that would break=20 > current valid usages of std::vector as template template parameter.=20 > For exactly that reason (That is: Don't change template parameter=20 > lists of existing Library components), Library implementations are not=20 > allowed to add further template parameters with default parameters,=20 > see=20 > > http://cplusplus.github.io/LWG/lwg-closed.html#94=20 > =20 > > - Daniel=20 > P0522R0, resolving Core issue 150, should significantly alleviate the code= =20 breakage aspect of this problem. But it certainly breaks ABI all over the= =20 place. --=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. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/449d2b1f-5a52-428b-b5d8-54f7c47014bc%40isocpp.or= g. ------=_Part_648_1857871506.1488128777349 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Sunday, February 26, 2017 at 8:18:41 PM UTC+8, = Daniel Kr=C3=BCgler wrote:
2017= -02-26 11:25 GMT+01:00 =C2=A0<inkwizyt...@gmail.com>:
>> What are the other variances that people want?
>
> This could fix problem with `std::vector<bool>`, current vec= tor would be:
> `omni_vector<Typename, ov_compress_bool>` and if you want &q= uot;normal" behavior
> you will use directly `omni_vector<bool>`.

It is very unlikely that this will happen, because that would break
current valid usages of std::vector as template template parameter.
For exactly that reason (That is: Don't change template parameter
lists of existing Library components), Library implementations are not
allowed to add further template parameters with default parameters,
see

http://cplusplus.github.io/LWG/lwg= -closed.html#94

- Daniel

P0522R0, resolving Core issue 150, should s= ignificantly alleviate the code breakage aspect of this problem. But it cer= tainly breaks ABI all over the place.

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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/449d2b1f-5a52-428b-b5d8-54f7c47014bc= %40isocpp.org.
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