220 30190 <2225413.PkzHcSPZVx@tjmaciei-mobl1> article Path: news.gmane.org!.POSTED!not-for-mail From: Thiago Macieira Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: enum_cast proposal Date: Tue, 03 Jan 2017 17:09:14 -0200 Lines: 44 Approved: news@gmane.org Message-ID: <2225413.PkzHcSPZVx@tjmaciei-mobl1> References: <2998762.etaySSRi7N@tjmaciei-mobl1> <85e681ea-20cb-5d87-d337-6b472e35eb11@wanadoo.fr> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1483470567 9731 195.159.176.226 (3 Jan 2017 19:09:27 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 3 Jan 2017 19:09:27 +0000 (UTC) User-Agent: KMail/5.3.3 (Linux/4.8.13-1-default; KDE/5.28.0; x86_64; ; ) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCB4TK757YBRBXXNV7BQKGQEOSSMBVA@isocpp.org Tue Jan 03 20:09:21 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f70.google.com ([209.85.215.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cOUSR-0000zo-1c for gclcip-std-proposals@m.gmane.org; Tue, 03 Jan 2017 20:09:15 +0100 Original-Received: by mail-lf0-f70.google.com with SMTP id b14sf182776423lfg.6 for ; Tue, 03 Jan 2017 11:09:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=from:to:subject:date:message-id:user-agent:in-reply-to:references :mime-version:content-transfer-encoding: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=veoVAwpkY++PgE/aNo1udHch3fES91aZcj1Awysw8BI=; b=IZCy+KUWTccNZq+jKg+VpIu7U/Q9nhOPFgEfAUG4TlZTRUR1SRCAe0rNdWmqB6/8Cu ACTlLij/d0R8tzrcV9m2RclOaXtbJpXG3QHjNN5pgupxt+XdyWGeD21/tNtnjrgE4cYt MPdKCYFhPWX+PdzOs7UfhI7+76GVOovzcPeg9fNYa130+HCeAAdQdmrSjbVLQ4Pux9F0 WpJ/D+0MvXuZewgeYSO9nnBRHWBIF9N7mJEbfswBBrBkiT3hqK7dceaq1vJdqsHWGUuv 8SqujefJtdqFYgRt03wOSIYlkw9S/Z66Vhapr0GiqEVj45OOzXOUd3hEfXCvUB2PQCkA X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:user-agent :in-reply-to:references:mime-version:content-transfer-encoding :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=veoVAwpkY++PgE/aNo1udHch3fES91aZcj1Awysw8BI=; b=APyhxTvvPQsfMRaHFJnkeaprB4oB3mVKSnaadM97fL67ffHQXoKZ2SMOxMbWo2eW7S n3Eq/p+CeK1WW1Hx7rZTbGCpsYcbcB+PIQSAOIxf4a4S7DmV2YZnHu3T34LLdF8kuK0Z nHBBniT8ivKYF2zJ/6BwL8z5tU6qlNd8TYbC01FWWEbPVF01Ys7FSmLncvoTZhPGNsBf usuaEUbDi7uQ2PueGhdXevoNezY32BuNz9b/4MAOosBwZLz2NNASs1vzGkdmt+7uDBf4 2XtMee2k+/g0wjB1AaBB57aDTbCjBawb8tWvWmx4CrJgAm4w5KYOocHEMiueFf+pi7Bl X-Gm-Message-State: AIkVDXIA/zoKpIphHoZzs6meD2XIAjOD/1nP39Vrc5uBC6CWtJbKIOaS0xvCEo2XYs2J7Q== X-Received: by 10.25.170.17 with SMTP id t17mr5310909lfe.20.1483470559451; Tue, 03 Jan 2017 11:09:19 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.143.203 with SMTP id r194ls5990100wmd.21.canary-gmail; Tue, 03 Jan 2017 11:09:18 -0800 (PST) X-Received: by 10.28.55.203 with SMTP id e194mr50868121wma.6.1483470558336; Tue, 03 Jan 2017 11:09:18 -0800 (PST) Original-Received: from gondolin.macieira.info (gondolin.macieira.info. [78.47.120.188]) by mx.google.com with ESMTP id 6si74514664wmq.165.2017.01.03.11.09.18 for ; Tue, 03 Jan 2017 11:09:18 -0800 (PST) Received-SPF: pass (google.com: domain of thiago@macieira.org designates 78.47.120.188 as permitted sender) client-ip=78.47.120.188; Original-Received: from tjmaciei-mobl1.localnet (unknown [187.34.234.250]) by gondolin.macieira.info (Postfix) with ESMTPSA id ECB3E11B7FC for ; Tue, 3 Jan 2017 11:09:16 -0800 (PST) In-Reply-To: <85e681ea-20cb-5d87-d337-6b472e35eb11@wanadoo.fr> X-Original-Sender: thiago@macieira.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of thiago@macieira.org designates 78.47.120.188 as permitted sender) smtp.mailfrom=thiago@macieira.org 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:30190 Archived-At: On ter=C3=A7a-feira, 3 de janeiro de 2017 18:53:02 BRST Vicente J. Botet Es= criba=20 wrote: > Le 03/01/2017 =C3=A0 16:56, Thiago Macieira a =C3=A9crit : > > On ter=C3=A7a-feira, 3 de janeiro de 2017 07:06:10 BRST m.cencora@gmail= ..com > > wrote: > >=20 > > Also, where did that optional come from? If it's going to use optional, > > then it needs to be a library feature. >=20 > I'm not for the optional return type, but we have already a lot of cases > where syntactic sugar as range-based for loop and structure binding > depends on library. > So I'm not sure this could be an argument against optional. Those are quite different things. In fact, they show how to *not* depend on= =20 the library in the first place. Ranged fors and structured bindings only=20 require that functions called begin, end, and get exist. So I can add any= =20 function of my own with those names and it will work. And structured bindin= gs=20 are very specifically *not* a std::tuple. They're something different. So enum_cast could return an optional-like opaque type defined by the compi= ler=20 (like structured bindings and lambdas) which can be converted to std::optio= nal=20 on construction. --=20 Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org Software Architect - Intel Open Source Technology Center --=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/2225413.PkzHcSPZVx%40tjmaciei-mobl1. .