220 40459 article Path: news.gmane.org!.POSTED!not-for-mail From: John McFarlane Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Optional fixed point arithmetic was standardised into C in 2008. Why doesn't C++ adopt it? 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[209.85.220.65]) by mx.google.com with SMTPS id e80-v6sor4796200iof.130.2018.10.09.11.56.27 for (Google Transport Security); Tue, 09 Oct 2018 11:56:27 -0700 (PDT) Received-SPF: pass (google.com: domain of mcfarlane.john@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; X-Received: by 2002:a6b:5104:: with SMTP id f4-v6mr18951955iob.114.1539111386613; Tue, 09 Oct 2018 11:56:26 -0700 (PDT) In-Reply-To: X-Original-Sender: john@mcfarlane.name X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of mcfarlane.john@gmail.com designates 209.85.220.65 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:40459 Archived-At: --000000000000781a480577d04b88 Content-Type: text/plain; charset="UTF-8" On Tue, Oct 9, 2018, 19:53 John McFarlane wrote: > On Mon, Oct 8, 2018, 20:45 Niall Douglas wrote: > >> > So, learned something new from WG14 today, namely that C standardised >>> optional fixed point arithmetic back in 2004, with a second edition in >>> 2008. I didn't know that before. Here is a pre-publication draft of the >>> standard ISO/IEC TR 18037:2008: >>> > >>> > http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1169.pdf >>> > >>> > Why doesn't WG21 simply adopt this instead of the (library) fixed >>> point arithmetic proposals currently before it? >>> >>> Probably for the same reason why complex is a library type in C++; >>> WG21 thinks it can do better with a library approach than >>> with a built-in one. >>> >> >> Well, sure. But I really wish the authors of the relevant papers before >> WG21 described in their motivation why they think that a library approach >> is clearly superior to an already published standard. That's a fairly high >> bar, in my opinion, to meet when essentially proposing "I don't think the >> standardised way is sufficient for reasons A, B and C. Here's what I >> propose instead ...". And I don't remember such explanatory text in >> motivations. I was hoping somebody could link me to such a text, I could >> read it, and as someone without domain expertise in fixed point arithmetic, >> I could go away feeling satisfied WG21 is on the right track on this. >> >> Niall >> > > Here's a brief mention of N1169: > http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0037r5.html#N1169 > I'm not sure it's ever come up before. I assumed the advantages of > parameterizing exponent were fairly obvious. > I nearly forgot: here's much the same conclusion being made in the other C++ fixed-point proposal. http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0106r0.html#prior_art John > >> -- >> 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/1f9ce37e-8a55-4e48-8f84-6ace99617160%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/CABPJVnSNtVyY-kp%2B2WjKKjSH7Arey-h36iuv8Ui%3Dv6uO9vBe4A%40mail.gmail.com. --000000000000781a480577d04b88 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Tue, Oct 9, 2018, 19:53 John= McFarlane <john@mcfarlane.name> wrote:
> So, learned something new from WG14 today, namely that C stan= dardised optional fixed point arithmetic back in 2004, with a second editio= n in 2008. I didn't know that before. Here is a pre-publication draft o= f the standard ISO/IEC TR 18037:2008:
>
> http://www.open-std.org/jtc1/sc22/wg= 14/www/docs/n1169.pdf
>
> Why doesn't WG21 simply adopt this instead of the (library) fi= xed point arithmetic proposals currently before it?

Probably for the same reason why complex is a library type in C++;
WG21 thinks it can do better with a library approach than
with a built-in one.

Well, sure. But I really wish the auth= ors of the relevant papers before WG21 described in their motivation why th= ey think that a library approach is clearly superior to an already publishe= d standard. That's a fairly high bar, in my opinion, to meet when essen= tially proposing "I don't think the standardised way is sufficient= for reasons A, B and C. Here's what I propose instead ...". And I= don't remember such explanatory text in motivations. I was hoping some= body could link me to such a text, I could read it, and as someone without = domain expertise in fixed point arithmetic, I could go away feeling satisfi= ed WG21 is on the right track on this.

Niall
=

Here's a brief mention of N1169:=
http://www.open-std.org/jtc1/sc22/wg21/do= cs/papers/2018/p0037r5.html#N1169
I'm not sure it's ever com= e up before. I assumed the advantages of parameterizing exponent were fairl= y obvious.

I nearly forgot:= here's much the same conclusion being made in the other C++ fixed-poin= t proposal.

= John

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