220 29020 article Path: news.gmane.org!.POSTED!not-for-mail From: Jonathan Coe Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: [propagate_const] Implicit conversion to T Date: Thu, 20 Oct 2016 22:08:51 +0100 Lines: 86 Approved: news@gmane.org Message-ID: References: <1f43ffe8-b267-4c8c-8834-f3e60035f18d@isocpp.org> <7f61be69-4f4c-40a5-9199-805edc90b428@isocpp.org> <13a71b20-8fd3-4a29-9279-716a2c9082a6@isocpp.org> <7abb6203-6ca7-4e04-ab6a-dc6a60e223ca@isocpp.org> <60ae1a96-7a31-491d-bcf8-c81590544006@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a114798d22cb5e3053f5255cb X-Trace: blaine.gmane.org 1476997736 1996 195.159.176.226 (20 Oct 2016 21:08:56 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 20 Oct 2016 21:08:56 +0000 (UTC) To: "std-proposals@isocpp.org" Original-X-From: std-proposals+bncBC2JVFPBRAHBBZPEUTAAKGQENXDOWFY@isocpp.org Thu Oct 20 23:08:51 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f69.google.com ([209.85.213.69]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bxKa3-0008D3-Ig for gclcip-std-proposals@m.gmane.org; Thu, 20 Oct 2016 23:08:51 +0200 Original-Received: by mail-vk0-f69.google.com with SMTP id 2sf54759756vkb.2 for ; Thu, 20 Oct 2016 14:08:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject: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=IBcQ1cMxeIfFmLg7+TKL4oR894PApsqsO0i8sMkYsCo=; b=k1gjfmy+ijlqqtq4YIkFUoV0HLVEozPsbU9a0lEsweqYFUyp7U9at1eAeClvl5G0Aw 6Ni0O0NXNNJmHBS8jfpVRFo2433JAWCFkzwD9n7X6U5bu0Vv/W7T7XIHbVMm/bQ+atUR IsbQAu/LA/m+utB1NSxY0aEV+HWW+6zf6k8EbiBDjIsPORHsxPXU+RrX80kDJgGSY9Gm KB9/yXtFborpeTucmOu4yv5T72/tGoDUcHhS7jgB7TCVqGw+GmJ+4YGOjuA1EOV7fzO8 2U5gIkBwsPXmm6JiofXb85z9PUemO6m3Q1/WtexvS4R+O8Ul8mbES7eeqm160UOe92lV Wggg== X-Gm-Message-State: AA6/9Rm2Vqd8o9T7YyWCOuoLJPdMlygzSdrE/kMZ5rP/YyRTVX2ocYym2HcXyuy+CbuU+g== X-Received: by 10.31.132.7 with SMTP id g7mr4448494vkd.41.1476997733834; Thu, 20 Oct 2016 14:08:53 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.1.21 with SMTP id 21ls5924970otu.49.gmail; Thu, 20 Oct 2016 14:08:53 -0700 (PDT) X-Received: by 10.55.75.215 with SMTP id y206mr2410989qka.26.1476997732971; Thu, 20 Oct 2016 14:08:52 -0700 (PDT) Original-Received: from mail-qk0-x232.google.com (mail-qk0-x232.google.com. [2607:f8b0:400d:c09::232]) by mx.google.com with ESMTPS id d73si28489925qkc.232.2016.10.20.14.08.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 20 Oct 2016 14:08:52 -0700 (PDT) Received-SPF: pass (google.com: domain of jonathanbcoe@gmail.com designates 2607:f8b0:400d:c09::232 as permitted sender) client-ip=2607:f8b0:400d:c09::232; Original-Received: by mail-qk0-x232.google.com with SMTP id n189so119411104qke.0 for ; Thu, 20 Oct 2016 14:08:52 -0700 (PDT) X-Received: by 10.55.214.211 with SMTP id p80mr2728586qkl.235.1476997732404; Thu, 20 Oct 2016 14:08:52 -0700 (PDT) Original-Sender: jonathanbcoe@gmail.com Original-Received: by 10.237.33.237 with HTTP; Thu, 20 Oct 2016 14:08:51 -0700 (PDT) In-Reply-To: <60ae1a96-7a31-491d-bcf8-c81590544006@isocpp.org> X-Original-Sender: jonathanbcoe@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of jonathanbcoe@gmail.com designates 2607:f8b0:400d:c09::232 as permitted sender) smtp.mailfrom=jonathanbcoe@gmail.com; dmarc=fail (p=NONE dis=NONE) header.from=me.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:29020 Archived-At: --001a114798d22cb5e3053f5255cb Content-Type: text/plain; charset=UTF-8 Adding `const_type` so that `const propagate_const` is implicitly convertible to `const_type_t` seems pretty appealing to me. `get_underlying` is very much like a cast operation, it was added so the user can discard const_propagation when required. On 20 October 2016 at 21:53, wrote: > Of course, makes sense. > The constness we care about is the one of the instance, we can't > communicate and "transfer" it on creation or assignment to a new instance. > > -- > 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/60ae1a96-7a31-491d- > bcf8-c81590544006%40isocpp.org > > . > -- 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/CAAbBDD-Txt57g_XEpKhRaJhW7WXLen%2BemuXKgn2g19DzK5m9Bg%40mail.gmail.com. --001a114798d22cb5e3053f5255cb Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Adding `const_type` so that `const propagate_const<T>= ;` is implicitly convertible to `const_type_t<T>` seems pretty appeal= ing to me.

`get_underlying` is very much like a cast ope= ration, it was added so the user can discard const_propagation when require= d.

On 20 Octob= er 2016 at 21:53, <mihailnajdenov@gmail.com> wrote:<= br>
Of course, makes se= nse.
The constness we care about is the one of the instance, we = can't communicate and "transfer"=C2=A0it on creation or assig= nment to a new instance.

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