220 29338 <68625755-8e0d-4030-afd5-d081371f7295@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: mihailnajdenov@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: std::byte thoughts Date: Wed, 2 Nov 2016 02:27:17 -0700 (PDT) Lines: 178 Approved: news@gmane.org Message-ID: <68625755-8e0d-4030-afd5-d081371f7295@isocpp.org> References: <7da80620-e4bd-40eb-a4ec-4f3c2dcb2c98@isocpp.org> <2350841.Z7lUCKSumT@tjmaciei-mobl1> <3e64b220-79ae-4108-ba1c-9785494fc434@isocpp.org> <2128372.NTAZafObDQ@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1661_2064418561.1478078837367" X-Trace: blaine.gmane.org 1478078842 6165 195.159.176.226 (2 Nov 2016 09:27:22 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 2 Nov 2016 09:27:22 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCUJ3A7GRAPRB5XC43AAKGQEV4FJAUA@isocpp.org Wed Nov 02 10:27:18 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f197.google.com ([209.85.161.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1c1rpE-0000sf-8j for gclcip-std-proposals@m.gmane.org; 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Wed, 02 Nov 2016 02:27:18 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.61.97 with SMTP id a88ls3966745otc.41.gmail; Wed, 02 Nov 2016 02:27:17 -0700 (PDT) X-Received: by 10.157.15.143 with SMTP id d15mr103743otd.2.1478078837781; Wed, 02 Nov 2016 02:27:17 -0700 (PDT) In-Reply-To: <2128372.NTAZafObDQ@tjmaciei-mobl1> X-Original-Sender: MihailNajdenov@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:29338 Archived-At: ------=_Part_1661_2064418561.1478078837367 Content-Type: multipart/alternative; boundary="----=_Part_1662_2067262189.1478078837367" ------=_Part_1662_2067262189.1478078837367 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Wednesday, November 2, 2016 at 8:43:35 AM UTC+2, Thiago Macieira wrote: > > Em ter=C3=A7a-feira, 1 de novembro de 2016, =C3=A0s 22:16:32 PDT, Nicol B= olas=20 > escreveu:=20 > > On Wednesday, November 2, 2016 at 12:55:46 AM UTC-4, Thiago Macieira=20 > wrote:=20 > > > That would also not be a good idea because, unsigned char is, by=20 > > > defintion, a=20 > > > byte. Why should we have (more) types that mean exactly the same=20 > thing,=20 > > > and=20 > > > this time in all platforms, by definition?=20 > >=20 > > Because "unsigned char" *also* means "unsigned character". With just=20 > > `unsigned char`, there is no way to distinguish between manipulating=20 > bytes=20 > > and manipulating unsigned characters.=20 > >=20 > > That's what `byte` is for, as a type: a way to semantically=20 > differentiate=20 > > between operations on bytes and operations on characters. The types can= =20 > be=20 > > inter-convertible, numerically speaking, but they don't mean the same= =20 > thing.=20 > > I'm sorry, I don't agree that there's a distinction in the first place.= =20 > Bytes=20 > are used more often than just copying around. If you add, subtract, shift= =20 > left=20 > or right, perform bitwise operations, etc, you need the value. If I need= =20 > the=20 > value, then a zero is a zero is a zero, a 0x40 is still a 0x40.=20 > > ... > But while that may be true, what's the point of an *unsigned* char? If yo= u=20 > want to do character operations, you use char. If you're using unsigned= =20 > char,=20 > that's because you want a byte, plain and simple. By this argument, we=20 > already=20 > have the distinction between character operations and byte operations.=20 > > --=20 > Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org=20 > Software Architect - Intel Open Source Technology Center=20 > All byte is trying to do is to make "unsigned char" officially different=20 then char. Better name, better name, no conversions and limited operations. Also it *does* define bitwise ops.=20 As for arithmetics, well It seems a bit odd indeed, but lets not=20 forget that char is too small on the one hand, and, on the other, unsigned= =20 is not considered a good type for math (as per '16 cppcon talk). The idea is to be pure storage format not representing values (strings or= =20 math) without a cast.=20 --=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/68625755-8e0d-4030-afd5-d081371f7295%40isocpp.or= g. ------=_Part_1662_2067262189.1478078837367 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Wednesday, November 2, 2016 at 8:43:35 AM UTC+2= , Thiago Macieira wrote:
Em ter= =C3=A7a-feira, 1 de novembro de 2016, =C3=A0s 22:16:32 PDT, Nicol Bolas esc= reveu:
> On Wednesday, November 2, 2016 at 12:55:46 AM UTC-4, Thiago Maciei= ra wrote:
> > That would also not be a good idea because, unsigned char is,= by
> > defintion, a
> > byte. Why should we have (more) types that mean exactly the s= ame thing,
> > and
> > this time in all platforms, by definition?
>=20
> Because "unsigned char" *also* means "unsigned char= acter". With just
> `unsigned char`, there is no way to distinguish between manipulati= ng bytes
> and manipulating unsigned characters.
>=20
> That's what `byte` is for, as a type: a way to semantically di= fferentiate
> between operations on bytes and operations on characters. The type= s can be
> inter-convertible, numerically speaking, but they don't mean t= he same thing.

I'm sorry, I don't agree that there's a distinction in the = first place. Bytes=20
are used more often than just copying around. If you add, subtract, shi= ft left=20
or right, perform bitwise operations, etc, you need the value. If I nee= d the=20
value, then a zero is a zero is a zero, a 0x40 is still a 0x40.

...
But while that may be true, what's the point of an *unsigned= * char? If you=20
want to do character operations, you use char. If you're using unsi= gned char,=20
that's because you want a byte, plain and simple. By this argument,= we already=20
have the distinction between character operations and byte operations.

--=20
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
=C2=A0 =C2=A0Software Architect - Intel Open Source Technology Center

All byte is trying to do is to make &q= uot;unsigned char" officially different then char. Better name, better= name, no conversions and limited operations.
Also it does= define bitwise ops.
As for arithmetics, well It seems a bit odd= indeed, but lets not forget=C2=A0that char is too small on the one hand, a= nd, on the other,=C2=A0unsigned is not considered=C2=A0a good type for math= (as per '16 cppcon talk).

The idea is to be p= ure storage=C2=A0format not representing values=C2=A0(strings or math) with= out a cast.

--
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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/68625755-8e0d-4030-afd5-d081371f7295= %40isocpp.org.
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