220 38676 article Path: news.gmane.org!.POSTED!not-for-mail From: Tony V E Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Three way comparison of arrays Date: Fri, 15 Jun 2018 15:34:02 -0400 Lines: 194 Approved: news@gmane.org Message-ID: References: <9c6a84e4-66a2-4a25-8372-c7a6c7b8de25@isocpp.org> <60dffd75-ebc3-4e4c-8666-f304be8f6136@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="0000000000005db539056eb34c0a" X-Trace: blaine.gmane.org 1529091118 14671 195.159.176.226 (15 Jun 2018 19:31:58 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 15 Jun 2018 19:31:58 +0000 (UTC) To: Standard Proposals Original-X-From: std-proposals+bncBCUZ5QWKNQIKXKMQ3ECRUBE4L7OZG@isocpp.org Fri Jun 15 21:31:54 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oi0-f69.google.com ([209.85.218.69]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fTuRt-0003gi-H7 for gclcip-std-proposals@m.gmane.org; Fri, 15 Jun 2018 21:31:53 +0200 Original-Received: by mail-oi0-f69.google.com with SMTP id j7-v6sf6452704oib.19 for ; Fri, 15 Jun 2018 12:34:04 -0700 (PDT) ARC-Seal: i=2; a=rsa-sha256; t=1529091244; cv=pass; d=google.com; s=arc-20160816; b=bvBKz+zVdmrTNMBnGYxB1hX3NIUs8mtB4SPSu+4dPBJhlD2Mml4FlSbCMHa5H+9MYb zPTBDogjZX4XZb6V7nfaQnaO/4MNDLIBhQiL6Mly5QkXAAnoRlj5zzgHAM9Kxnxb7C0H ev1hhbpOXbVICG0He5WoJvL4UjVWVh5xieqZ5Dswo0sOEjdpm2dNQL1vkw4MvOve5d5q EvIW6Yi/t2dSJJlrvs5zyqNSFbmbDOniIMTNZGUYLp27thO7XKo0nvIdQVM3sSN2n1tg s6Ya44EZCVzGEubu5JviJ3aJToiEnnnhm47Wi2znMfczzB6rYRbnB+loVpe3QlXy5B6q X+Cw== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post :list-id:mailing-list:precedence:reply-to:to:subject:message-id:date :from:references:in-reply-to:mime-version:arc-authentication-results :arc-message-signature:dkim-signature:arc-authentication-results; bh=TwruRPzv4HeudpEjoKC/I6h5jzqtwOEOw4lJX/BZsbA=; b=m6SvO4/zU5kHlC6FOvNZWL8+F9EimFQjT3UYO0Uvhi07N/MVSatm46EG5b0g+HhiRK 5Fzm3d10MIFTpu0wIQ3DiiOWVfZ7Akg1I9/RpLHGRc4XYLrcx2dspSPFlXGOSHbKeE18 FuIdJnl/BDWIb7yCNdEAiK+ZXklhmLjraflGTgdL0xlRgvOowFGCJ2YgcRmwxbZaIVaA H5ffMvO8TqebUYpwX6NxjgvZsE7Wi+BvMVXVFEBDUG02Rp0FJNfrmyoJBCuU7KspedEu w4wsZWM4dxwjdFOzDDSp7ljm2p5bjanVt8beFzuOWZOq0eZtLRacp8Mc6db3+r7BCg7i 0CMQ== ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Kf2kkrXt; spf=pass (google.com: domain of tvaneerd@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=tvaneerd@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject: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; bh=TwruRPzv4HeudpEjoKC/I6h5jzqtwOEOw4lJX/BZsbA=; b=yELjodqScy73L+myB/je8YeEKfDXu38UCRv9FW128ksoN+aH6tcWXNZry1cIT5/n3k PlsvOkCkXmTY6tsXk4KbIfYkPK4e0Bz3pyg4T+avACXvw3CvpYN9IhxC7qwT7nYJOeoV yx3qd61OePD6ycHvr7lK1d6L9NpL1GyYFbKu+nxZyOxCOofR9UcIf4AzQsG72n4eadan k5g+Hx+hmOXZ0jt54mYrxJfLlHbrKnXLdOXrlfOEtKC+T13y8azb+i0T+LmHgTVSc2UH CkpyfgNN9aFOhwESnOhtf+fYBKYAzDESoxJvG6+ch7ttMAAAcV4YfrTUoPXuld6I/R/7 HEjQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject: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=TwruRPzv4HeudpEjoKC/I6h5jzqtwOEOw4lJX/BZsbA=; b=tvcWiytdbzUKOVbu3qiC6U1sOfLkIK9v0K0Eam/xQ2rscV1jMXiQGiGXvhEnqgq7jR a4HFguMGaQd8X/5trUDkcSJZvAMfglz4E2iaI+UVx8rtLNlzpXDASJjY9k+dQw+RaME3 hKsbrO0PPgnzyiZxBxOfIk4jE9LtV5xY2OSxu5zErvgCe4At1rTRW4DJAHhHzYLZcxKF L+3KNQGaKLfd2zVLEQnz8YF1vjoh4+kf5KoFni9j5yrcL/daTHS3HyJru2XGR8oq9w1g EJz0df0rE6NGti76O33bG6N+b8JhgtcM+XD/y32+2ly3Pq53f7pwDJUtia6s0tn98ijH Kl/Q== X-Gm-Message-State: APt69E23eGHIZTFrvmG3BV0AhMeZqqgQajGRVJSZCWQsc85GAO0ehgBW 9SUtcWZx92lj9SOBEI4D0LUtuQ== X-Google-Smtp-Source: ADUXVKLCVdAYPXDy7LzM8sDNPcrDuqPGSAhn5WhFGRqq0MN9PRtImS8zh6/qSR8XkYE0hAfsIBm+5w== X-Received: by 2002:a9d:3d76:: with SMTP id a109-v6mr1363551otc.51.1529091244430; Fri, 15 Jun 2018 12:34:04 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 2002:a9d:7313:: with SMTP id e19-v6ls4049848otk.20.gmail; Fri, 15 Jun 2018 12:34:03 -0700 (PDT) X-Received: by 2002:a9d:6245:: with SMTP id i5-v6mr1970996otk.253.1529091243358; Fri, 15 Jun 2018 12:34:03 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1529091243; cv=none; d=google.com; s=arc-20160816; b=hQHyh4B2JVrI1zeFfsyn1I8nmpTApIQvpxeyPeICA23J3sTUjiKo1orYQJXb7Rm8IE /8u40c9LIi6BDGHTToDpZ7gTVEr+6LYRXlK4kgjagIjEYIN1QTrEJi1N7h+wf6UMw2j+ OJWwFq4UKLla79G5/t+df8lD0ZSgP35jVB5PBQiuCs9UJgvf+fAcikKrGTLGIwN7gtT5 lZLdzlj270LQV60sPxQxNzNcctb2oOCzz8UoQeIx3LIaRgNjEHcvtiZ0KFsd9DVflteN 4ijSKD8CuXva9mGGOjJM30LfByrs7k59g7qP20lRahXelupEwQSomEw2PfEf3i2dH+KW 5FeQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=to:subject:message-id:date:from:references:in-reply-to:mime-version :dkim-signature:arc-authentication-results; bh=jn8W40p6ruc7moomCRUZQ4xFTO3iSgLJPeQvbqqDMKM=; b=0Zgj20z+uPC4BRmEBjWxDshm4nAy9OZ1W6cKGg7zmC+YZvTijrsCSeFV21UKqP7wbC TbjEFNuG9YqnTA97vTzgGO6NU7h/MFgSnY5/Un//AiHPYYO5PLjCZVIjSvc0Nvp8eSf4 FSjXd5PIDwQDUaWbzpbKA2LfYy+cZiRxk9JeGelukSm0BRdHPs0nVy3FsSrvcNP21b5A tXnFk9NKNvmlQ+z0Ie4iSBHjNybAx1nVjZl5EDhRh8uPrsmR0SQpy5GfUEssQ9/esCG+ /W2xlpWJNk5F056lSzOqdCK+LMXHE4PC7TIXq7XXAxLrzy2EB/gAfztt7aadUBwrTdg9 Jmnw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Kf2kkrXt; spf=pass (google.com: domain of tvaneerd@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=tvaneerd@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Original-Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id m18-v6sor3455635otd.336.2018.06.15.12.34.03 for (Google Transport Security); Fri, 15 Jun 2018 12:34:03 -0700 (PDT) Received-SPF: pass (google.com: domain of tvaneerd@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 2002:a9d:a56:: with SMTP id 80-v6mr1947971otg.256.1529091242962; Fri, 15 Jun 2018 12:34:02 -0700 (PDT) Original-Received: by 2002:a9d:4c99:0:0:0:0:0 with HTTP; Fri, 15 Jun 2018 12:34:02 -0700 (PDT) In-Reply-To: <60dffd75-ebc3-4e4c-8666-f304be8f6136@isocpp.org> X-Original-Sender: tvaneerd@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Kf2kkrXt; spf=pass (google.com: domain of tvaneerd@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=tvaneerd@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE 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:38676 Archived-At: --0000000000005db539056eb34c0a Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Jun 15, 2018 at 2:45 PM, wrote: > This is a weak argument. We sacrifice the consistency of the operator<=3D= > > (works for all types) for doubtful consistency of copy and compare (of a > single type). We should be fixing language corner cases so it does what > programmer intents. > Typically it is more important to be "locally" or "self" - consistent, than to be "broadly" or "cross" - consistent. So we keep arrays self-consistent, but lose consistency across <=3D>. > So I'd rather have operator<=3D> for arrays in all cases, and fix array > copying as well. > > Regards, > Maciej > > W dniu pi=C4=85tek, 15 czerwca 2018 19:45:12 UTC+2 u=C5=BCytkownik Barry = Revzin > napisa=C5=82: >> >> >> >> On Friday, June 15, 2018 at 10:34:10 AM UTC-5, m.ce...@gmail.com wrote: >>> >>> Hi, >>> >>> can we finally write idiomatic comparison code for arrays with three wa= y >>> compare? >>> >>> bool foo() >>> { >>> int a1[4] =3D { 1, 2, 3, 4 }, a2[4] =3D { 1, 2, 3, 4 }; >>> return (a1 <=3D> a2) =3D=3D 0; >>> } >>> >>> >>> >> No. This is explicitly rejected by design. Quoting from >> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0515r3.pdf: >> >> For arrays, we don=E2=80=99t provide comparison if the array is not copy= able in >>> the language, to keep copying and comparison consistent. Note that for = two >>> arrays, arr1<=3D>arr2 is ill-formed because the array-to-pointer conver= sion >>> is not applied >>> >> >> Additionally, in Rapperswil, the two-way comparisons between arrays (i.e= .. >> a1 =3D=3D a2) were deprecated. So now at least they both consistently wi= ll not >> work. >> >> -- > 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/60dffd75-ebc3-4e4c- > 8666-f304be8f6136%40isocpp.org > > . > --=20 Be seeing you, Tony --=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/CAOHCbitza9P%2Bn4%3DnJDX7xcPVa-JqOW_iotaJ%2BBh%2= B2N8Mx6Biug%40mail.gmail.com. --0000000000005db539056eb34c0a Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Fri, Jun 15, 2018 at 2:45 PM, <m.cencora@gmail.com> wrote:
This is a = weak argument. We sacrifice the consistency of the operator<=3D> (wor= ks for all types) for doubtful consistency of copy and compare (of a single= type). We should be fixing language corner cases so it does what programme= r intents.


Typic= ally it is more important to be "locally" or "self" - c= onsistent, than to be "broadly" or "cross" - consistent= ..
So we keep arrays self-consistent, but lose consistency across = <=3D>.


=C2=A0
So I'd rather have opera= tor<=3D> for arrays in all cases, and fix array copying as well.
<= /div>

Regards,
Maciej
=C2=A0
W dniu pi=C4=85tek, 15 czerwca 2018 19:45:12 UTC+2 u=C5=BCytkow= nik Barry Revzin napisa=C5=82:


On Friday, June 15, 2018 at 10:34:10 AM UTC-5, m.ce.= ...@gmail.com wrote:
Hi,

can we finally write idiomatic comparison code = for arrays with three way compare?

bool=C2=A0foo()
{
=C2=A0 =C2=A0 int a1[4] =3D {= 1, 2, 3, 4 }, a2[4] =3D { 1, 2, 3, 4 };=
=C2= =A0 =C2=A0 return (a1 <=3D> a2) =3D=3D 0;
}



No. This is explicitly reject= ed by design. Quoting from=C2=A0=C2=A0http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0515r= 3.pdf:

For arrays, we don=E2=80=99t provide comparison if the array is not c= opyable in the language, to keep copying and comparison consistent. Note that for two arrays, arr1<=3D>arr2 is= ill-formed because the array-to-pointer conversion is not applied

Additionally,= in Rapperswil, the two-way comparisons between arrays (i.e. a1 =3D=3D a2) = were deprecated. So now at least they both consistently will not work.=C2= =A0

--
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-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/60df= fd75-ebc3-4e4c-8666-f304be8f6136%40isocpp.org.



--
Be seeing = you,
Tony

--
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/CAOHCbitz= a9P%2Bn4%3DnJDX7xcPVa-JqOW_iotaJ%2BBh%2B2N8Mx6Biug%40mail.gmail.com. --0000000000005db539056eb34c0a-- .