220 5320 article Path: news.gmane.org!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Allowing any integral type as an argument for user defined literal operators Date: Sun, 7 Jul 2013 00:17:35 +0300 Lines: 123 Approved: news@gmane.org Message-ID: References: <80016e3a-2dc8-4887-b59b-a8aff20439e0@isocpp.org> <03a23bfd-10ab-40db-a7f9-3cbd177a2d52@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=047d7b6dcf5214ebb504e0de571a X-Trace: ger.gmane.org 1373145460 26833 80.91.229.3 (6 Jul 2013 21:17:40 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 6 Jul 2013 21:17:40 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC5JHI7A7ALRB34S4KHAKGQELDEQ3RA@isocpp.org Sat Jul 06 23:17:39 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yh0-f69.google.com ([209.85.213.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UvZrM-0007Dm-QQ for gclcip-std-proposals@m.gmane.org; Sat, 06 Jul 2013 23:17:37 +0200 Original-Received: by mail-yh0-f69.google.com with SMTP id b12sf4288257yha.8 for ; Sat, 06 Jul 2013 14:17:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-beenthere:mime-version:in-reply-to:references:date:message-id :subject:from:to:x-original-sender:x-original-authentication-results :reply-to:precedence:mailing-list:list-id:x-google-group-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe :content-type; bh=04rJMaICx6ThYyf/F9V8ZzvBLuWo99NmaFsRCE5g12A=; b=hE7z1YnabqTrQC1zE/Nx2mLKqjW9y03PLmYLAgDUsUCAA1PJOc3lud3MJ2z5Lf8Whe ZWj3uDMyQ0u7sbf0RYhd8RKdTZbNQpBjflcFl/z+FTz0C4poWLA1v4uuLaEBCnr2g8qo Ye8IA++kmA6RIXohLlDnshZlxgFhGJR9vVrkXtjqaSKXa7pLUK/6IoQtsyX7BISz5jCZ gneBSM4GT813qgh1VXjg9BrczYSltkaaPh7ZvMBtIW3kffQXlJVZ8qMAu+RwE9+nNsM2 MnKaUv7VEgTZNyQd87UtBoBNlH+JX9N483AfzkfXpMyRvklKRple2tsGZciXiFnOtOsF RJmQ== X-Received: by 10.224.29.76 with SMTP id p12mr18421008qac.5.1373145455746; Sat, 06 Jul 2013 14:17:35 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.12.233 with SMTP id b9ls1392792qec.14.gmail; Sat, 06 Jul 2013 14:17:35 -0700 (PDT) X-Received: by 10.49.26.202 with SMTP id n10mr9587307qeg.60.1373145455363; Sat, 06 Jul 2013 14:17:35 -0700 (PDT) Original-Received: from mail-qc0-x22c.google.com (mail-qc0-x22c.google.com [2607:f8b0:400d:c01::22c]) by mx.google.com with ESMTPS id c9si3939087qac.92.2013.07.06.14.17.35 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 06 Jul 2013 14:17:35 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c01::22c as permitted sender) client-ip=2607:f8b0:400d:c01::22c; Original-Received: by mail-qc0-f172.google.com with SMTP id j10so1721501qcx.31 for ; Sat, 06 Jul 2013 14:17:35 -0700 (PDT) X-Received: by 10.49.94.41 with SMTP id cz9mr9438277qeb.83.1373145455190; Sat, 06 Jul 2013 14:17:35 -0700 (PDT) Original-Received: by 10.224.52.71 with HTTP; Sat, 6 Jul 2013 14:17:35 -0700 (PDT) In-Reply-To: <03a23bfd-10ab-40db-a7f9-3cbd177a2d52@isocpp.org> X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c01::22c as permitted sender) smtp.mail=ville.voutilainen@gmail.com; dkim=pass header.i=@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:5320 Archived-At: --047d7b6dcf5214ebb504e0de571a Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 7 July 2013 00:15, Micha=C5=82 Dominiak wrote: > > It's not supposed to take any integral types. The operator takes an >> unsigned type because any negation >> happens outside it. Since we already have such a restriction for the typ= e >> a literal operator accepts, it's >> not a far stretch to have a further limitation. I wouldn't mind it >> accepting any unsigned integral type, >> but I don't see it a big deal that you have to have a certain signature >> for a literal operator. >> > > Ok, s/any/any unsigned/. > > >> Not allowing multiple kinds of integral types as literal operator >> parameters also avoid having >> to deal with overload resolution for the literal operators, and not >> allowing narrow types avoids >> having to deal with narrowing conversions. >> > > No-one says allowing any unsigned argument type would allow overloading (= I > think it would be a counter-feature, really). And since you know all the > values passed to the operator at compile time, no narrowing would ever > happen - just slap the user with an error about the value being to big fo= r > given type. > > > > Ok, so any unsigned type, no overloading with multiple integral types, and any narrowing is ill-formed. With that recipe, I wouldn't mind seeing a proposal about this. I'm not going to write one myself. I may be able to present one if necessary. --=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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. --047d7b6dcf5214ebb504e0de571a Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable



On 7 July 2013 00:15, Micha=C5=82 Dominiak <griwes@griwes.info> wrote:

It's not supposed= to take any integral types. The operator takes an unsigned type because an= y negation
happens outside it. Since we already have such a restriction for= the type a literal operator accepts, it's
not a far stretch to have= a further limitation. I wouldn't mind it accepting any unsigned integr= al type,
but I don't see it a big deal that you have to have a certain signature= for a literal operator.

<= /div>
Ok, s/any/any unsigned/.=C2=A0
= =C2=A0
Not allowing multiple kinds of integral types= as literal operator parameters also avoid having
to deal with overload resolution for the literal operators, and not al= lowing narrow types avoids
having to deal with narrowing conversions.
=C2=A0
No-on= e says allowing any unsigned argument type would allow overloading (I think= it would be a counter-feature, really). And since you know all the values = passed to the operator at compile time, no narrowing would ever happen - ju= st slap the user with an error about the value being to big for given type.=




Ok, so any unsigned ty= pe, no overloading with multiple integral types, and any narrowing is ill-f= ormed. With
that recipe, I wouldn't mind seeing a proposa= l about this. I'm not going to write one myself. I may be able to
present one if necessary.

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