220 37205 article Path: news.gmane.org!.POSTED!not-for-mail From: Vincent Reverdy Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: General purpose utilities for template metaprogramming and type manipulation Date: Sat, 3 Mar 2018 22:55:38 -0800 (PST) Lines: 142 Approved: news@gmane.org Message-ID: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_10232_1978397646.1520146538613" X-Trace: blaine.gmane.org 1520146419 25433 195.159.176.226 (4 Mar 2018 06:53:39 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 4 Mar 2018 06:53:39 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCYPFAORZMKRB25Q53KAKGQE646EPEI@isocpp.org Sun Mar 04 07:53:35 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f197.google.com ([209.85.217.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1esNWY-0005xg-3V for gclcip-std-proposals@m.gmane.org; Sun, 04 Mar 2018 07:53:34 +0100 Original-Received: by mail-ua0-f197.google.com with SMTP id d35sf8845281uag.0 for ; Sat, 03 Mar 2018 22:55:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=g9x7hXym8IGkXo/roy5+rU3H/LXVQ+oykGk8o64oHck=; b=Vn1JvXsv/kYtCgcS/l7z5mVcwm+DUW/7ebWrpRGSX5T1Hc113OinofCSSr9NkJZzY5 qN8a2dR4taFfWSshXKWUU2TFeNCo+DYXApIQSb0rixSy7/sMU9CLfHeKtUmtK3BckH9A aj7zLSarClQvzOlGXMv35iBE9+AL6fQQdpHfTLZOVvA3+VjS4KcNeqB8cloOOpBIobUN qbr+5tXGH3GAlcT/v0FRtcrKfzm8wOJOnRUJm8Q3Utl6/TMIs0haLc6LaptKBBwH2x77 jiu43KXDV2TtROjEhJBk1YGlr83eMbktzATWtElKvjmsG2iInNJBEP48wlz53apZhhEM kSpg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=g9x7hXym8IGkXo/roy5+rU3H/LXVQ+oykGk8o64oHck=; b=PzvGjT4OecRHLrgaf7ojgPOH8Q92FvZWy1d02YmTx+hRvzDT9S1zswzCE9hhPaNrD/ xy9Sm6Ra5sF+N/hvr66g+nYP0OEhpb02w/2/UIewvxNw8o8+sWjYfrMuDnsOVo6Stqfi fyjjSPbH4f2LMF2vUnadndXPgoOwFzFNS4DLsivamr9GkNKa5YtxoxqsODdatcpMRnhM zXdIzoaz2gAzrnEf1Ozf637xSHIvYvpzGW1EpZDAhehgJNdcx0wjQ35RDhn9Ts6lYvAk 2647/iTXoW8ji5mZSmON8Rz3ToCZpEHOZrMv0xnrVaL/iCM5Mtkw5KPSKq/0Jey/iyTt cHuA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:subject:mime-version :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=g9x7hXym8IGkXo/roy5+rU3H/LXVQ+oykGk8o64oHck=; b=MjZSuGYIo1WaIcc/QTcT9NySHaHIpa4oXRaH9Apx/5X7KirZvQaunwLZAGqY3GiqpY 8LBXFTEg2WaP2elu6RN5VCYp2jIqjj4H8S22xOfSJsqXsMoMrLQQu4PDNuSZc7jpwE3F qlxvdydNmh+EWd516iPXlM8GMCGeQISBaU/rIUZTg2JRIEJo5WA9MNNESB0cf1hdWKlw pGtEAMOtT/WP8nrCECdu5R2wyTNiTaWNjxeM3m1P3DAspPK/0AXObWWZoU06cD/mfZ5/ FrR4KNmwd+z6Z4AXknhLh8ipFBY49vj33ZRQnoVnDXvbJq5OVXszPrJ8Vkupdo6CP30D mhpw== X-Gm-Message-State: APf1xPDT5yiNBwcSIln/6I/coqFItR8J+h1lERL8GYYESuBf6RuWtwgz jOfRR+dUFonjCLuNqQGIcKPRnQ== X-Google-Smtp-Source: AG47ELtOqWlAhysiBJI5lPGuUdlHyKEEV3MW/UaRRruIq4/FsvWGK/WJ+6VKkp0t0tWD75O4CBQ73A== X-Received: by 10.31.168.8 with SMTP id r8mr5242284vke.51.1520146540570; Sat, 03 Mar 2018 22:55:40 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.31.205.194 with SMTP id d185ls7400199vkg.20.gmail; Sat, 03 Mar 2018 22:55:39 -0800 (PST) X-Received: by 10.31.161.197 with SMTP id k188mr1199897vke.8.1520146539105; Sat, 03 Mar 2018 22:55:39 -0800 (PST) X-Original-Sender: Vince.Rev@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:37205 Archived-At: ------=_Part_10232_1978397646.1520146538613 Content-Type: multipart/alternative; boundary="----=_Part_10233_2019831081.1520146538613" ------=_Part_10233_2019831081.1520146538613 Content-Type: text/plain; charset="UTF-8" Hey, I was starting to think about putting together a proposal to add minor helper classes to either type_traits/utility/tuple to help with some of the operations done again and again when doing template metaprogramming. Here is a list of a few I can think of, but I would have liked to hear other suggestions. Names are just indicative, and bikeshedding would happen for all of these types. - *std::blank*, defined as an empty struct struct blank{}; - *std::pack*, to hold a parameter pack of type template struct pack{}; - *std::convertible*, a type convertible to anything struct convertible{template constexpr operator T() const noexcept;}; - *std::copy_qualifiers*, a type traits copying ref and cv qualifiers from one type to another template struct copy_qualifiers {using type = /* cv-ref qualfiers of From applied to To*/;}; Other suggestions? -- 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/e3415a75-7e20-48dd-9e24-0e4681f46e53%40isocpp.org. ------=_Part_10233_2019831081.1520146538613 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hey,

I was starting to think about putting together= a proposal to add minor helper classes to either type_traits/utility/tuple= to help with some of the operations done again and again when doing templa= te metaprogramming.
Here is a list of a few I can think of, but I would = have liked to hear other suggestions. Names are just indicative, and bikesh= edding would happen for all of these types.

  • std::blank, defined as an empty struct
    struct blank{};
  • std::pack, to = hold a parameter pack of type
    template <class.= ... T> struct pack{};
  • std::= convertible, a type convertible to anything
    struct convertible{template <class T&g= t; = constexpr<= span style=3D"color: #000;" class=3D"styled-by-prettify"> operator T() const noexcept;};
  • std::copy_qualifiers, a type traits copying ref and cv qualifiers from one type to another
    template <class From, class<= /span> To> struct copy_qualifiers {using type =3D /* cv-ref qualfiers of From applied to To*/;};

Ot= her suggestions?

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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/e3415a75-7e20-48dd-9e24-0e4681f46e53= %40isocpp.org.
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