220 33026 article Path: news.gmane.org!.POSTED!not-for-mail From: Igor Baidiuk Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: std::optional - support for sentinel values Date: Thu, 29 Jun 2017 04:50:11 -0700 (PDT) Lines: 62 Approved: news@gmane.org Message-ID: References: <6e23864f-827a-4bdb-89de-a60d8f5be993@isocpp.org> <9f81f2b9-958c-4018-9f78-a6ac2e425899@isocpp.org> <730d0077-5a80-4dce-8250-19be62b1a23b@isocpp.org> <20170629111649.5132370.85419.32148@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_3254_1280160015.1498737011346" X-Trace: blaine.gmane.org 1498737016 16740 195.159.176.226 (29 Jun 2017 11:50:16 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 29 Jun 2017 11:50:16 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDK4F76SSIIBB5GS2PFAKGQERIAVGII@isocpp.org Thu Jun 29 13:50:10 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f200.google.com ([209.85.217.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dQXxY-0003wr-L4 for gclcip-std-proposals@m.gmane.org; Thu, 29 Jun 2017 13:50:08 +0200 Original-Received: by mail-ua0-f200.google.com with SMTP id 35sf19922862uax.6 for ; Thu, 29 Jun 2017 04:50:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=ksR85KNjUGsVkclrPwaSmSKDIZOqAIyKFCFGLDm+QcM=; b=TA8+pbckmrFhoOhDPHuWU0u3WJGNGnML5bpheNkZ/YCV2Rl6WgBOLSi3LJwSjWnjg/ nhT3naFAvV7HnQghCPC3zusvlGbFLRCKEfJ00g6/0lXI0Gz/XalCA2tBlFVT3wQWXOpK CDwA4E9cAF7lIG2aYnCuyXZ1gfmAoZBNl+cQeO7Uy1ejhFFx4ZXqnehWJqEI7xh13H3h V2IL61yRvBUdU/uOkVmvh/mffEXZBSkviX4iX0usbaBBTeoFUtXSYuFQUEt37dqQq/qB 7j8RxO1THolwn8LwLmgPHF72a4SnoTAZfb6UvwRgSmzQGHtSIIxlY9R7zSuSOwjnrImz p6+w== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=ksR85KNjUGsVkclrPwaSmSKDIZOqAIyKFCFGLDm+QcM=; b=esP0Go/guNbthDVAB+Jv2Mf7nmJ0u+yyq0stmAn+wxtUEsTCqxAoVbuUioBmmVdMLf 8Koni0EijR19qr/iXLmrF4zLH/2pjvEpnsXsjoq589xqWe4xd6pMmWjgweD4iusvgVwX Kulws1oPsNMbRU0R/1lRUZ6dbowDaWLSMpm+zcNhMEb3144cR243E5CsAXvYrv5dkXQ7 l54355ebQjDmaFriIfyLGccL3j7U8u9j7SG60fx6EVAHoj/KAVc3ue3+lEC1yX/DVeBL TBvxbSgPu2UweRHwkbh88MeIEKUAlXYqsoyAVOv9jlF4JAHriYnTdA1Y1AeIsmpXX12O mdhw== 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:in-reply-to:references :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=ksR85KNjUGsVkclrPwaSmSKDIZOqAIyKFCFGLDm+QcM=; b=MlO+X/hdkbIopjR6+zMNpbMtlEqblInRD0fZKJjv2Wp93YDgHw8sw0FFhM6YHdLASL XOUQQUowyjioRNBLvcYBQmOq1sR3gmakGoScHuah0B5bBqWmF+NgnAzhW7GKrkHAUXE/ 6Xo0gxsRd+OdGxe1r/xlhZuckAEGVEbRvx9mMe/nY6i7qfwICfWei70g25DvDO9c4U9D O7DcQYVNiwYO5mwnz5IMmnhvTs3hCGxc/r8Q6P3bURueGdJjZkEgtNW8qUvN83uFHMK/ wJH9Ho58s2dWb41lRVE57Z1v/163AGBjTOcZus7oBhNhVvXPvlDmOIJj6H6DDpiWreuO Ezyg== X-Gm-Message-State: AKS2vOz5sogl/qW98fAqJNR5FBEZ5I2MIOCvyRi4c2a6b3A+zRDROn1D 515wGBANsEhWWg/y X-Received: by 10.31.158.200 with SMTP id h191mr8081035vke.40.1498737013519; Thu, 29 Jun 2017 04:50:13 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.0.208 with SMTP id 199ls658352ita.6.gmail; Thu, 29 Jun 2017 04:50:11 -0700 (PDT) X-Received: by 10.36.3.72 with SMTP id e69mr341536ite.1.1498737011927; Thu, 29 Jun 2017 04:50:11 -0700 (PDT) In-Reply-To: <20170629111649.5132370.85419.32148@gmail.com> X-Original-Sender: target.san@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:33026 Archived-At: ------=_Part_3254_1280160015.1498737011346 Content-Type: multipart/alternative; boundary="----=_Part_3255_1838034707.1498737011346" ------=_Part_3255_1838034707.1498737011346 Content-Type: text/plain; charset="UTF-8" If we introduce such "special wrapper", we'll lose in ergonomics, even if this will save us from ABI breakage. As for ABI, major compilers like MSVC or GCC do ABI breakage on major version bump anyway. Though I'd rather put that particular question aside for now. Let's imagine we're up to a new type. On Thursday, June 29, 2017 at 2:16:52 PM UTC+3, Tony V E wrote: > > std::optional> > > -- 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/caf31531-e7f3-4446-93b4-b1dcca612a99%40isocpp.org. ------=_Part_3255_1838034707.1498737011346 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
If we introduce such "special wrapper", we'l= l lose in ergonomics, even if this will save us from ABI breakage.
As fo= r ABI, major compilers like MSVC or GCC do ABI breakage on major version bu= mp anyway.
Though I'd rather put that particular question aside for = now. Let's imagine we're up to a new type.

On Thursday, Jun= e 29, 2017 at 2:16:52 PM UTC+3, Tony V E wrote:
std::optional<std::opt_sentineled<int,-1>>= ;

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To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/caf31531-e7f3-4446-93b4-b1dcca612a99= %40isocpp.org.
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