220 23245 <0c101390-8938-483d-91a8-e1f4a83bdefb@isocpp.org> article Path: news.gmane.org!not-for-mail From: Casey Carter Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: n4428 and Tuple-like access interface reflection Date: Mon, 28 Dec 2015 21:08:25 -0800 (PST) Lines: 163 Approved: news@gmane.org Message-ID: <0c101390-8938-483d-91a8-e1f4a83bdefb@isocpp.org> References: <56770133.7070701@wanadoo.fr> <5681D877.3010101@wanadoo.fr> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_55_1173483533.1451365706073" X-Trace: ger.gmane.org 1451365714 4117 80.91.229.3 (29 Dec 2015 05:08:34 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 29 Dec 2015 05:08:34 +0000 (UTC) Cc: reflection@isocpp.org To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBD2MLWWVRQMRBS5KRC2AKGQEEKXGXSQ@isocpp.org Tue Dec 29 06:08:31 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-io0-f199.google.com ([209.85.223.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1aDmWM-0001On-2K for gclcip-std-proposals@m.gmane.org; Tue, 29 Dec 2015 06:08:30 +0100 Original-Received: by mail-io0-f199.google.com with SMTP id 77sf95717533ioc.2 for ; Mon, 28 Dec 2015 21:08:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:content-type:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=ttcNgMuTCAiPYjPqx0gXetzIcneNUbJvKBZHiKGIpYA=; b=Mz6m68UD384R94VSOrfmc0zJz7J1iLtIz4+KZifFkmci5BdG++ofZSExUmHy0V9vM4 ceynHnVG69GuBQ9d1RWMNOvJmxvEvnbGM/I+AF9VLimH/hmZ39IPPXwtVjurJsdIfLN/ oo/p8aj9yuEM/KZW2Qbol9zPykjeUMngwgLp03amaYNB+XlUPoFMFfpMxHJ2lckCDhAa U805slwGFjRsChWqGBWGKuUoOshNe3Vd96w/CxFwg16P0xAfTv8AMcz2seNgSBzgKhTd Hwzfa+Nn8dRw3SUAmddIZBoXEPXRt+DyS6YXl3FkjAPxeQPq5nVNZ+GVy+pUcTGDRH5X sf1Q== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:content-type:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=ttcNgMuTCAiPYjPqx0gXetzIcneNUbJvKBZHiKGIpYA=; b=f4C9wsniJG6WO/EbIgLNEKq/t4IanIH5qzGW0JhlezTCkQEiYee1pMbUr0sEjK91kr bbMGYb54To7wL/kVvrsP6wKFcjej0rKckHnbAfSX6om1h5dfG5yTKiazNhOgclwFkPJj jLDI9eZMth0qZRXIebt4F6S0l2yoRSqLlicOoOCKIV2tpRgbIN0Svklj+sbpdgvOfh1j +JWKpXZO41FS87e4H52MCnKhD28TTvib74ygtPnox7LblwpQXizAEejO+lW6ug/X2eEn QMeFsTcYisWy5p2rm5ZhZ2eG/03Qzg6I6RuaJIotOzDtLJ/usmotpe5cyJzOfEWDFsFr 9wvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-type:x-original-sender :reply-to:precedence:mailing-list:list-id:x-spam-checked-in-group :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=ttcNgMuTCAiPYjPqx0gXetzIcneNUbJvKBZHiKGIpYA=; b=Ebyq62wNiQizAUukKV9Jr3lGjfNAYAQun/9liWxRwOdkdwzwRPZme8VMkxGfP95yZs YfIuONi8r51AulIixgTXQh807fDtGCvhcHiFscQhlJf/XVwUphhJUmo+tYM6VreYQqyc 1zSvVC8ddXAtNXgWF3+udRajibz9leHuvLXgfoNGGpHQmkbZ/OdEr5bMUGJrZpLewww4 2GVP3q4giPMCkRSvVEjN4IfZ9wq+cQSnl0UXdOMiExPFdViovo02XzaN+tUpkFB58RBT fr+lFY/MbwGMUPR+jz7eOLMUG4Qb2oGDResWyrhdQGrqQOQz7oeEx0UYbUuQC4Zu58IS 3dQA== X-Gm-Message-State: ALoCoQkavt3bHtXFvSsfcXeprXruCkT5B/1+viiZwE8a56VMeLJES/YEylabHFQxbdqqz5EP/hhHp/CT12a3Hgsr+DvhxA7Lhw== X-Received: by 10.50.3.98 with SMTP id b2mr49556650igb.8.1451365708564; Mon, 28 Dec 2015 21:08:28 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.122.9 with SMTP id lo9ls3064596igb.16.gmail; Mon, 28 Dec 2015 21:08:27 -0800 (PST) X-Received: by 10.50.25.196 with SMTP id e4mr223077igg.8.1451365707634; Mon, 28 Dec 2015 21:08:27 -0800 (PST) In-Reply-To: <5681D877.3010101@wanadoo.fr> X-Original-Sender: cartec69@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:23245 Archived-At: ------=_Part_55_1173483533.1451365706073 Content-Type: multipart/alternative; boundary="----=_Part_56_1528315012.1451365706074" ------=_Part_56_1528315012.1451365706074 Content-Type: text/plain; charset=UTF-8 On Monday, December 28, 2015 at 6:48:58 PM UTC-6, Vicente J. Botet Escriba wrote: > > I have added a trait tuple_like that states if I want the generation > > template > struct tuple_like: false_type {}; > > but I don't see how to make the specialization conditional to this traits > without adding an Enabler parameter > > template > struct tuple_size; > template > struct tuple_element; > > Is there a way without changing the std::tuple_size and std::tuple_element > template parameters? > What would be the the correct way to do that? > > template requires tuple_like::value struct tuple_size : /* ... */; template requires tuple_like::value struct tuple_element : /* ... */; -- --- 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. Visit this group at https://groups.google.com/a/isocpp.org/group/std-proposals/. ------=_Part_56_1528315012.1451365706074 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Monday, December 28, 2015 at 6:48:58 PM UTC-6, Vicente J. Botet Escr= iba wrote:
=20 =20 =20
I have added a trait tuple_like that states if I want the generation

template <class T>
struct tuple_like: false_type {};

but I don't see how to make the specialization conditional to this traits without adding an Enabler parameter

=C2=A0=C2=A0=C2=A0 templat= e <class T, class Enabler=3Dvoid>
=C2=A0=C2=A0=C2= =A0 struct tuple_size;
=C2=A0=C2=A0=C2=A0 template <size_t N, class T, class Enabler=3Dv= oid>
=C2=A0=C2=A0=C2=A0 struct tuple_element;

Is there a way without changing the std::tuple_size and std::tuple_elemen= t template parameters?
What would be the the correct way to do that?

templ= ate <class T>
requires tuple_like<T>::value
struct tuple_size<T> : /* ... */;


template <size_t N, class T>
requires= tuple_like<T>::<= span style=3D"color: #000;" class=3D"styled-by-prettify">value
struct tuple_element<N, T> := /* ... */= ;

<= /div>


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