220 11955 <8761iv4ijm.fsf@euclid.axiomatics.org> article Path: news.gmane.org!not-for-mail From: Gabriel Dos Reis Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: should lambda to function pointer conversion become constexpr Date: Thu, 17 Jul 2014 17:28:13 -0700 Organization: axiomatics.org Lines: 45 Approved: news@gmane.org Message-ID: <8761iv4ijm.fsf@euclid.axiomatics.org> References: <153e8b0e-4f1b-413c-b2e2-7831bd4385e7@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1405643306 27399 80.91.229.3 (18 Jul 2014 00:28:26 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 18 Jul 2014 00:28:26 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCSYNQUB2UHRBHWUUGPAKGQELQHNF2A@isocpp.org Fri Jul 18 02:28:16 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oa0-f71.google.com ([209.85.219.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1X7w24-00070a-3J for gclcip-std-proposals@m.gmane.org; Fri, 18 Jul 2014 02:28:16 +0200 Original-Received: by mail-oa0-f71.google.com with SMTP id g18sf9468264oah.6 for ; Thu, 17 Jul 2014 17:28:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:subject:in-reply-to:organization :references:sender:date:message-id:lines:mime-version :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type :content-transfer-encoding; bh=R87sSgvjRcslOGxl9TGu06qY5XdTW4Wi0Cuwl8dOza8=; b=TsNeTvWJJ+W54nKlBxSXIi9H7HlXGUGkny56t/SpDpCLs9bxSAfbmhlDWZ1dXgVKQN vulH2CQFylL5JLvb1rAluMttbACNTaRIOWg+v0+DgUaTk6veTaLZMHU4Gf+M/X4VhirQ AqVKUZBYgiMXYiJA/Ntln3dq7cLk1u6R69eVTL/llgh7dhBvqfIsuXjPwiXBH99k91F0 sKUjaKvWcC2AeHDoDuQWX5M1S9C0fh8W8Wc3cLqmHJuFalaL/tWOAWg2bAcpfbW4Rb8s z2NYiQt4zRnrRvpZZCVlbR2tzQCO03ZzFKkExo3MN37tVzENJAJ7LfuH X-Gm-Message-State: ALoCoQnFim9HPGiA0TA2umQfGqK+N7KwGZYIjLz5fRgy3gTaoQ1w2pPiSe5lA9hrgUZrEAhoTJha X-Received: by 10.182.241.169 with SMTP id wj9mr582568obc.14.1405643295231; Thu, 17 Jul 2014 17:28:15 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.87.33 with SMTP id u1ls777746obz.79.gmail; Thu, 17 Jul 2014 17:28:14 -0700 (PDT) X-Received: by 10.182.66.130 with SMTP id f2mr1046272obt.84.1405643294307; Thu, 17 Jul 2014 17:28:14 -0700 (PDT) Original-Received: from mail.axiomatics.org (www.axiomatics.org. [66.228.53.191]) by mx.google.com with ESMTP id pb14si8002064oeb.98.2014.07.17.17.28.14 for ; Thu, 17 Jul 2014 17:28:14 -0700 (PDT) Received-SPF: none (google.com: gdr@axiomatics.org does not designate permitted sender hosts) client-ip=66.228.53.191; Original-Received: from euclid.axiomatics.org (localhost [IPv6:::1]) by mail.axiomatics.org (Postfix) with ESMTP id CBE7BE770 for ; Thu, 17 Jul 2014 17:28:13 -0700 (PDT) In-Reply-To: <153e8b0e-4f1b-413c-b2e2-7831bd4385e7@isocpp.org> (frrrwww@gmail.com's message of "Wed, 16 Jul 2014 10:51:47 -0700 (PDT)") Original-Sender: gdr@axiomatics.org Original-Lines: 34 X-Original-Sender: gdr@axiomatics.org X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: gdr@axiomatics.org does not designate permitted sender hosts) smtp.mail=gdr@axiomatics.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:11955 Archived-At: frrrwww@gmail.com writes: | Hello, |=20 | I sometimes use the following pattern: |=20 | static const struct { | =C2=A0 =C2=A0 const char* name; | =C2=A0 =C2=A0 void (*func)(int); | } functions[] =3D { | =C2=A0 =C2=A0 =C2=A0{ "function1", [](int) { ... } }, | =C2=A0 =C2=A0 =C2=A0{ "function2", [](int) { ... } }, | =C2=A0 =C2=A0 =C2=A0... | }; |=20 | And when I look at the generated code, I see that this array gets | generated at runtime. |=20 | Ideally I would like to declare this array constexpr, and that would | work if I used named functions, however it does not for lambda, and I | cannot see any good reason for that. |=20 | As the function pointer conversion operator only exists for state-less | lambda, would'nt it make sense to define them as constexpr and their | conversion operator as well ? It does. It is sad that we needed to introduce a keyword to get the notion accepted by the C++ community, and we couldn't just infer 'constexprness' from the (inline) definition and use context. -- Gaby --=20 ---=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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. .