220 11275 article Path: news.gmane.org!not-for-mail From: Maurice Bos Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: return type sugar (orthogonal to auto foo() {} ) Date: Thu, 12 Jun 2014 15:49:26 +0200 Lines: 48 Approved: news@gmane.org Message-ID: References: <30a83c0d-00e6-462a-822e-a1789787ec05@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 X-Trace: ger.gmane.org 1402580999 18381 80.91.229.3 (12 Jun 2014 13:49:59 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 12 Jun 2014 13:49:59 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCNPPMPKVYDRB7O742OAKGQEBG35P3I@isocpp.org Thu Jun 12 15:49:54 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-la0-f70.google.com ([209.85.215.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Wv5O3-00008J-J1 for gclcip-std-proposals@m.gmane.org; Thu, 12 Jun 2014 15:49:51 +0200 Original-Received: by mail-la0-f70.google.com with SMTP id el20sf866098lab.5 for ; Thu, 12 Jun 2014 06:49:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=m-ou.se; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :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; bh=x762RtIJFvn5nrQDLgnRJ5HV6fLm81Nue5E27sYVuQQ=; b=jgh+EjFGACogPff+tk18oRfAX+p+2NgjTcLgW+TfIFX59bcHDXBy5NY02JFAnhzEgY GyGvFtDdHFDdoHgv0XziwG8Hf/F3ujQYnRhaXscpJeLRCH25WaiBUdQHe1YqIX+/1lay YtLoBp1WpO7tGpxlXC8O3AIsd102binwLu2tk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to: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; bh=x762RtIJFvn5nrQDLgnRJ5HV6fLm81Nue5E27sYVuQQ=; b=lV/hNNRsig15WGqwxRAHiDlh+zAu+S8Ki9PwGrBw3T23fTGSRHyEtCjvwop860lXy6 X/6UdZyL3D+LSBTKYEeczyMUrmwfweoQTC/cT2fxSZvXMmN6/I68v+D3j/tn0rUVnUq0 qb2XB5IpMamVfF0Hp5dib/5DDI4Kj5enY8Um5pklFQKATtmlgLtqCXBwOZTymw4NTbVd wDPBqB6x9obc4ZH5Ht++wXhAe6Y9WsNuVvCqAY37rjlJM8RFSLIBIQYDqHVbn0l8UNBr EnImKHaeH85yffX8shf+5/xCaHnsMuYPc3Z+xZWVRS1fdVcrR+UWXt0jytWZ0+xKJQ9P zWVQ== X-Gm-Message-State: ALoCoQnG4prvu2e2OuYWaAyy2s3t+qRfKmidz9NwXIf4rgA0tYLznUkvmCOPcJShppGIz65hKeEp X-Received: by 10.194.6.138 with SMTP id b10mr1039211wja.0.1402580991262; Thu, 12 Jun 2014 06:49:51 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.152.43.102 with SMTP id v6ls529046lal.99.gmail; Thu, 12 Jun 2014 06:49:48 -0700 (PDT) X-Received: by 10.112.62.231 with SMTP id b7mr1560151lbs.65.1402580988503; Thu, 12 Jun 2014 06:49:48 -0700 (PDT) Original-Received: from mail-la0-x235.google.com (mail-la0-x235.google.com [2a00:1450:4010:c03::235]) by mx.google.com with ESMTPS id u6si27097457lau.82.2014.06.12.06.49.48 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 12 Jun 2014 06:49:48 -0700 (PDT) Received-SPF: pass (google.com: domain of m-ou.se@m-ou.se designates 2a00:1450:4010:c03::235 as permitted sender) client-ip=2a00:1450:4010:c03::235; Original-Received: by mail-la0-f53.google.com with SMTP id ty20so703263lab.40 for ; Thu, 12 Jun 2014 06:49:48 -0700 (PDT) X-Received: by 10.152.6.37 with SMTP id x5mr32643995lax.15.1402580987738; Thu, 12 Jun 2014 06:49:47 -0700 (PDT) Original-Received: from mail-lb0-f177.google.com (mail-lb0-f177.google.com [209.85.217.177]) by mx.google.com with ESMTPSA id n3sm24414218lan.3.2014.06.12.06.49.46 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 12 Jun 2014 06:49:46 -0700 (PDT) Original-Received: by mail-lb0-f177.google.com with SMTP id u10so687235lbd.8 for ; Thu, 12 Jun 2014 06:49:46 -0700 (PDT) X-Received: by 10.112.76.66 with SMTP id i2mr30936694lbw.37.1402580986195; Thu, 12 Jun 2014 06:49:46 -0700 (PDT) Original-Received: by 10.112.173.72 with HTTP; Thu, 12 Jun 2014 06:49:26 -0700 (PDT) In-Reply-To: <30a83c0d-00e6-462a-822e-a1789787ec05@isocpp.org> X-Original-Sender: m-ou.se@m-ou.se X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of m-ou.se@m-ou.se designates 2a00:1450:4010:c03::235 as permitted sender) smtp.mail=m-ou.se@m-ou.se; dkim=pass header.i=@m-ou.se 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:11275 Archived-At: decltype(return) sounds good. I wished quite a few times I could've written this. (D has it in the form of typeof(return): http://dlang.org/declaration.html#Typeof) 2014-06-12 12:16 GMT+02:00 walter1234 : > Coming back to C++ from Rust, one thing begin to miss is the 2way type > inference: its a nice choice on their part, you write the types in the > signature, then the types in the body are inferred. > > But perhaps a significant amount of this use could be covered by having > sugar to access the declared return type of a function within its own body. > > imagine > > auto foo( args... )->decltype(....some expression based on args...) { > > return_type accumulator; // 'return_type' is a shortcut for > whatever this functions declared return type is.. > ... do stuff with accumulator... > > return accumulator. > } > > ways of doing that without a new keyword, perhaps 'decltype(return)' , any > other ideas.. > In some ways this would go beyond what rust currently does. (rust can't yet > use an expression for the return type, although making it generic often > works because of how the return types are inferred by callers) > > -- > > --- > 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. > Visit this group at > http://groups.google.com/a/isocpp.org/group/std-proposals/. -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. .