220 40529 article Path: news.gmane.org!.POSTED!not-for-mail From: John McFarlane Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Function to compute the absolute value of any integral value including signed minimums Date: Sun, 14 Oct 2018 16:17:53 +0100 Lines: 115 Approved: news@gmane.org Message-ID: References: <3f8200be-918a-44a0-a412-6f8f43da1c51@isocpp.org> <3a5821ae-c386-46b4-8e73-4bff8764679c@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="000000000000d2f2be057831d326" X-Trace: blaine.gmane.org 1539530163 30159 195.159.176.226 (14 Oct 2018 15:16:03 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 14 Oct 2018 15:16:03 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDS7B7WQUYOBBL54RXPAKGQERFDD6UY@isocpp.org Sun Oct 14 17:15:58 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-it1-f198.google.com ([209.85.166.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1gBi7a-0007iC-LH for gclcip-std-proposals@m.gmane.org; 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[209.85.220.41]) by mx.google.com with SMTPS id j201-v6sor13330118itj.5.2018.10.14.08.18.06 for (Google Transport Security); Sun, 14 Oct 2018 08:18:06 -0700 (PDT) Received-SPF: pass (google.com: domain of mcfarlane.john@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 2002:a24:b90a:: with SMTP id w10-v6mr12082911ite.101.1539530286099; Sun, 14 Oct 2018 08:18:06 -0700 (PDT) In-Reply-To: <3a5821ae-c386-46b4-8e73-4bff8764679c@isocpp.org> X-Original-Sender: john@mcfarlane.name X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of mcfarlane.john@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=mcfarlane.john@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:40529 Archived-At: --000000000000d2f2be057831d326 Content-Type: text/plain; charset="UTF-8" On Sun, Oct 14, 2018, 03:31 Bengt Gustafsson wrote: > For me the motivation for uabs() would more be to avoid unsigned/signed > mismatch errors by getting the result as an unsigned (which we know it > conceptually is after abs). > I consider a number being positive as different to a number being unsigned. I'd rather those two things (conversion and absolute value) remained separate concerns. > > This is very similar to the annoyance of floor, round and ceil returning > floats which we know have integer values, forcing us to write int(round(x)) > when using this with other ints to avoid compiler warnings. I think I saw > something about new floor() and similar functions being proposed, so > why not uabs? > I'm less adverse to abs() because the two concerns are more apparent but only slightly. If you're converting a float to an int, a necessary detail is how to approximate fractional values. So a convert() starts to become palatable. p0105 proposed something similar. I'm not familiar with the floor function you mention. > > -- > 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/3a5821ae-c386-46b4-8e73-4bff8764679c%40isocpp.org > > . > -- 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/CABPJVnTNih2bKvp6rVCWBpnv06KYuXDs3M0HwZSU_JPV3oG%3D8g%40mail.gmail.com. --000000000000d2f2be057831d326 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

On Sun, Oct 14, 2018, 0= 3:31 Bengt Gustafsson <= bengt.gustafsson@beamways.com> wrote:
For me the motivation for uabs() would more be t= o avoid unsigned/signed mismatch errors by getting the result as an unsigne= d (which we know it conceptually is after abs).

I consider a number being positive as different to a numbe= r being unsigned. I'd rather those two things (conversion and absolute = value)=C2=A0remained separate concerns.

This i= s very similar to the annoyance of floor, round and ceil returning floats w= hich we know have integer values, forcing us to write int(round(x)) when us= ing this with other ints to avoid compiler warnings. I think I saw somethin= g about new floor<int>() and similar functions being proposed, so why= not uabs?

I'm less a= dverse to abs<unsigned>() because the two concerns are more apparent = but only slightly.=C2=A0

If you're converting = a float to an int, a necessary detail is how to approximate fractional valu= es. So a convert<int, floor_tag>() starts to become palatable. p0105 = proposed something similar. I'm not familiar with the floor function yo= u mention.
<= div dir=3D"ltr">

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