220 40458 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 d8-v6sor8635063iof.125.2018.10.09.11.54.04 for (Google Transport Security); Tue, 09 Oct 2018 11:54:04 -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:f003:: with SMTP id w3-v6mr19187500ioc.12.1539111244018; Tue, 09 Oct 2018 11:54:04 -0700 (PDT) In-Reply-To: <1f9ce37e-8a55-4e48-8f84-6ace99617160@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 209.85.220.65 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:40458 Archived-At: --000000000000f837b50577d042fc Content-Type: text/plain; charset="UTF-8" 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. > > -- > 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/CABPJVnT71yWK6NOU2G80CM%3Doe2E_m%2BkX58MfML%2BYA%3DcYRfZeQw%40mail.gmail.com. --000000000000f837b50577d042fc Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Mon, Oct 8, 2018, 20:45 Niall Douglas <nialldouglas14@gmail.com> wrote:
> So, learned something new from WG14 today, namely that C = standardised optional fixed point arithmetic back in 2004, with a second ed= ition in 2008. I didn't know that before. Here is a pre-publication dra= ft of 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/docs/papers/2018/p00= 37r5.html#N1169
I'm not sure it's ever come up before. I ass= umed the advantages of parameterizing exponent were fairly obvious.

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