220 25309 article Path: news.gmane.org!not-for-mail From: Daniel Frey Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: [RFC] Call for considering "the big picture" re: tuples and parameter packs Date: Mon, 21 Mar 2016 18:36:07 +0100 Lines: 80 Approved: news@gmane.org Message-ID: References: <1FCE896E-001A-4F56-8866-FB201ABF3391@gmx.de> <6605C1A6-7DB7-4CDF-9B36-BEE95D90CAED@gmx.de> <56EF33D4.5070509@wanadoo.fr> <20160321032111.4898897.41547.8488@gmail.com> <5544dac2-1449-4039-89b9-e72e98a3db36@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 9.2 \(3112\)) Content-Type: multipart/signed; boundary="Apple-Mail=_592E0FE3-D687-4625-ADCD-F45271F78D17"; protocol="application/pgp-signature"; micalg=pgp-sha1 X-Trace: ger.gmane.org 1458581779 19640 80.91.229.3 (21 Mar 2016 17:36:19 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 21 Mar 2016 17:36:19 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDYYLHN44AERBCPCYC3QKGQEUI5Q7TA@isocpp.org Mon Mar 21 18:36:10 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lb0-f198.google.com ([209.85.217.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ai3kQ-0005Of-Eb for gclcip-std-proposals@m.gmane.org; Mon, 21 Mar 2016 18:36:10 +0100 Original-Received: by mail-lb0-f198.google.com with SMTP id wn5sf62697475lbb.3 for ; Mon, 21 Mar 2016 10:36:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:subject:from:in-reply-to:date:message-id:references:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=/39k1n1rlBqBGISUIBSVq9IGnFLyCYrLA1vB79CS/WA=; b=aKTHTNC0xvR/QDPcEQ5AUibC5o264SUatkXA9fYxNSpBjR+TraezOS1f+kqiJ7SWd3 i6FEGYDwSnhvbql2Y0ZDrgm3ZRT9sDSQwn1ZEEWJ3XN7nMJAws/ciUx3gsNT16Bvq3oT ikQjwg8lE9aFhXOo0uNOVQIiB8hivq5ZJLis5YKpu6TlUr1dUCjJJhoicuRT0LfYvo+G xX1/u+xBBRu82rLEjzCHXUl9lge1lv3w0K4lz55nLwazAbLzGMqrvHg1mge0/3DtT2B8 vy9w5uFePGc+VWLveKy/ZIHGb4Na5E3gZXAZenIBCTDdhh83xJxlQPT7xgIqw6aM2CN5 GEow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date :message-id:references:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=/39k1n1rlBqBGISUIBSVq9IGnFLyCYrLA1vB79CS/WA=; b=h0o4nY4fmiZo5w2/Qpy5yBoD+Bpj2Kl4INDvlVtD7UKO/Hchlge9eC7FRe1fvROCna LIknP4OjjiBJp6m3ohBT8uDJhqvKYPJm27gDBqgZALHJpzu1bajlKkIb457C1OssAIz3 I+qN9wAx5ut1apgzXkkjf2FLebtjGZRG5vJE7rE9wQs48aIUEWsjYYNiye3Z97KqqpUq 8vgT+zC5DlrdH708SIjL5TrB2trbP+KzWrsJNWpS2S9qlQ4+PgnTQ3KwX8QASeCn1KZP CfabV7idbharrAjTXK19Uygh4PdYuVIzcbjsOYC58lX8R4dm01lO5zEXyIi6M+3RUAUO cnvQ== X-Gm-Message-State: AD7BkJKcESIY0q3FoyDE4HMYZVyNvQXX0/T1O1a7SckxNb5Hf4QVGGqlJ2Z//A6bmv0t+g== X-Received: by 10.112.40.200 with SMTP id z8mr3929747lbk.16.1458581769941; Mon, 21 Mar 2016 10:36:09 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.46.14 with SMTP id u14ls700742wmu.22.canary; Mon, 21 Mar 2016 10:36:08 -0700 (PDT) X-Received: by 10.28.5.203 with SMTP id 194mr15957514wmf.101.1458581768817; Mon, 21 Mar 2016 10:36:08 -0700 (PDT) Original-Received: from mout.gmx.net (mout.gmx.net. [212.227.17.21]) by mx.google.com with ESMTPS id s3si14446405wmf.48.2016.03.21.10.36.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 21 Mar 2016 10:36:08 -0700 (PDT) Received-SPF: pass (google.com: domain of d.frey@gmx.de designates 212.227.17.21 as permitted sender) client-ip=212.227.17.21; Original-Received: from fiasko.fritz.box ([79.204.16.198]) by mail.gmx.com (mrgmx102) with ESMTPSA (Nemesis) id 0M7m0a-1Zn3Lk1LMm-00vP00 for ; Mon, 21 Mar 2016 18:36:08 +0100 X-Pgp-Agent: GPGMail 2.6b2 In-Reply-To: <5544dac2-1449-4039-89b9-e72e98a3db36@isocpp.org> X-Mailer: Apple Mail (2.3112) X-Provags-ID: V03:K0:lkXBbxGLqWFyVjQIPAptX5/9v20DHRJZ3t2N489R8eXwbQQm1R/ sqZQw+52ChPsp7ebCZEPdqD3jLHPMa4ftXzTe6jD5y8nppc28X8lZUZ9QMOcZwIhtFd+FCC 7MoitAelUgdbURugnRMdkAgxrvZwGUkrcYvnidDG48cdWVULaFDluSAO8j8say6Nx8JDRL8 a/WkJszIsP1F3dBhdD85g== X-UI-Out-Filterresults: notjunk:1;V01:K0:Hj0zj7rGn3s=:nCqEJ7qTdZ8F5Q2+PRJ/o1 6k0i8eh4YN8+s5ygUUPsgwXpoovK9fpWpmUnILSfq1MD25n0HQnOgvgoGQwXwfBhobmz1JQud MiYhKlzBlp3B6Yegi6ikjhRdPLer/kULU6sIz5OH/xSJRfKlMio1H019vZS09ywNKGbR4K4SG LiI7OCgvcUfTbNVrvIFNnH5kbvWJPdESsdoXugwKmZT5A+ilXRK+F007xjxR45B8TGV6eGbPY WmZ+bMFPjXpJ8ETXs5gnQYr7yznRFO+QNEXsp+UipF/iGcD4a+LKjO0nysIGqi1OrV92vJg+e Rzm1doOkhbIq3dIflEmByjmVebqXPK3Ac0BgH1rv+MsWoL+D2tzPssFd8HVOi5F/XUcnkqSgW 0ZVJwersVUT7eH9fBb3Wm+MG+0Q9PCUvKsLAdLtN1wcSNorUUF4FU1CxwZFIo+LAGlcIBoKXs f3XQZW94URIQAMHXqeyv1guI7++J+AF7fJeEjQgqmx3StvoDpw2icHkfyQgBztgNMnioGlG1T s65NPami85tZ6m/ztPC02bwhJMQyLSvwo+mGDBK9Ys5YGTZz9KbB8X/iGNX9xf5uti5HSCVCg G5ORd3hVmSUX6pwgqlA1zDwlS98qXbVk6mXx+vrikwaxau9WtVKOGUdHRp8PRiciWbRlG+hF3 Zh62YDtfKNR88tsFaUW3HQkOt3fITSRGW/oobMvxyjZxJ6nLqfGsYH8FjLEdJlCqLqQNpE+D9 +HjAHONMziNIfsAcI8q0N78e9zxQI8NqCaSzZ+vcV7nwq4PXaH3uC8P/JQ4= X-Original-Sender: d.frey@gmx.de X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of d.frey@gmx.de designates 212.227.17.21 as permitted sender) smtp.mailfrom=d.frey@gmx.de 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:25309 Archived-At: --Apple-Mail=_592E0FE3-D687-4625-ADCD-F45271F78D17 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 > On 21.03.2016, at 18:16, barry.revzin@gmail.com wrote: >=20 > On Monday, March 21, 2016 at 11:53:52 AM UTC-5, Matthew Woehlke wrote: >> On 2016-03-20 23:21, Tony V E wrote: >> > Could the member access syntax actually be s[N] for some struct or cla= ss s? >> > >> > ie just extend operator[] to allow the return type to be different for= different constexpr inputs. >>=20 >> I think that way lies madness... too easy to confuse CTI=C2=B9 with RTI= =C2=B2. >> Using a separate syntax makes it clear which is happening, and doesn't >> run into overload resolution problems for e.g. std::array that needs >> both. Also... >>=20 >> (=C2=B9 Compile-Time Indexing) >> (=C2=B2 Run-Time Indexing, obviously) >>=20 > Madness? This is C++! :) > Anyway, we basically have three categories: tuple (CTI only ever), vector= (RTI only ever), and array (both - which do the same thing really, except = CTI gives some nice safety mechanisms). We have std::get for CTI, but t= hat's because it was created as a library to support tuple, right? Is there= a conceptual reason why we wouldn't want tuple[0] to work and do something= like call tuple.operator[](integral_constant ) (or std::get<0>(= tuple) or something else along these lines)? I already said earlier that I think s[N] is the right syntax. The question to me is how to achieve this. Overloading on constexpr paramet= ers might be one option, templated constructors might be another solution -= or just the solution for allowing overloading. IIUC, it was already propos= ed. If you consider integral_constant to have a ctor that is able to deduce= size_t and 0 from the argument (0), you already have everything you need (= even int and 0 is OK). It also automatically ensures that the argument is a= constant. I fail to see why "confusing" CTI and RTI is a problem. If you misuse overl= oading or basically any other feature you will get confusing syntax or sema= ntics. But that doesn't mean that it's bad if used for the right use-cases = and to me, this is one of the obvious use-cases. Provide access to a tuple'= s elements via tuple::operator[]. -- Daniel --=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/C98AB9FE-13A6-433D-BCDC-B67C6DD9787D%40gmx.de. --Apple-Mail=_592E0FE3-D687-4625-ADCD-F45271F78D17 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iEYEARECAAYFAlbwMQcACgkQAUxJbew56yFPIgCbBa5DJEGS6ysBEjE3s3yZ9G2a ze4AoI4/mOXcJLAOGELNV9UKeOnLtT+w =2/4s -----END PGP SIGNATURE----- --Apple-Mail=_592E0FE3-D687-4625-ADCD-F45271F78D17-- .