220 20723 article Path: news.gmane.org!not-for-mail From: Matthew Woehlke Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Null -conditional and -coalescing operators Date: Wed, 23 Sep 2015 10:31:02 -0400 Lines: 64 Approved: news@gmane.org Message-ID: References: <4c3e2ee7-2159-4e93-a439-7d5c94c38c9c@isocpp.org> <6a0ad653-4764-483b-afb5-74d444be15d9@isocpp.org> <09547076-d049-4d87-acc3-b851e6518942@isocpp.org> <2242837.lDbo80ytWE@tjmaciei-mobl4> 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 1443018691 10469 80.91.229.3 (23 Sep 2015 14:31:31 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 23 Sep 2015 14:31:31 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC37LBFWUIFBBOHPRKYAKGQEQ57NTVQ@isocpp.org Wed Sep 23 16:31:23 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-la0-f71.google.com ([209.85.215.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Zel4r-00028j-PH for gclcip-std-proposals@m.gmane.org; Wed, 23 Sep 2015 16:31:21 +0200 Original-Received: by lamf6 with SMTP id f6sf24536724lam.1 for ; Wed, 23 Sep 2015 07:31:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:to:from:subject:date:lines:message-id:references :mime-version:content-type:user-agent:in-reply-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=YB0xka66GtbwtSW1PaRUe6+vtVAT4fgUXh61q4kQeS8=; b=aNG2K3OwPTUAvzcL9vx511EkT8n9vlYPZL5xNKYwfxZKuZVJwljQXIEgDukLmZIqqT 8uMQD8v/c4KKKgQ6I5VgsHj5bwNvXo2+4pmG1Ge9wSRuyiYi5npmQSwN5NpERc61HKBT kEla1kdjD15xyokd1+Y1bmsiTbxMqiJwFtN2So6jjRTlqVFQDvZY3nF+/t+NpJhOlQjk TQgHg3ujGUA/6+U8JSlybxvxIontBWJU7qmoYzIpQAw7y7d8gkxh+/RcuOq2sei8kGyz KuqkQYv+016fXWldLHkgozveRbYXF6YzWsUhb3kZ54KD/haICfTKz6Y1SHIi233Gd17P X-Gm-Message-State: ALoCoQldWaM0emF0SwIR4+MozzwhsMU0f5+zdsFYZiDhk0VkFFLV90306aeyJFBoW2ktm+FD+JxW X-Received: by 10.195.18.100 with SMTP id gl4mr5376308wjd.4.1443018681178; Wed, 23 Sep 2015 07:31:21 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.152.20.229 with SMTP id q5ls38921lae.17.gmail; Wed, 23 Sep 2015 07:31:18 -0700 (PDT) X-Received: by 10.25.29.85 with SMTP id d82mr4009849lfd.25.1443018678062; Wed, 23 Sep 2015 07:31:18 -0700 (PDT) Original-Received: from plane.gmane.org (plane.gmane.org. [80.91.229.3]) by mx.google.com with ESMTPS id y10si3986196lay.136.2015.09.23.07.31.17 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 23 Sep 2015 07:31:17 -0700 (PDT) Received-SPF: pass (google.com: domain of gclcip-std-proposals@m.gmane.org designates 80.91.229.3 as permitted sender) client-ip=80.91.229.3; Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1Zel4g-0001wb-Mm for std-proposals@isocpp.org; Wed, 23 Sep 2015 16:31:10 +0200 Original-Received: from tripoint.kitware.com ([66.194.253.20]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 23 Sep 2015 16:31:10 +0200 Original-Received: from mwoehlke.floss by tripoint.kitware.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 23 Sep 2015 16:31:10 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 55 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: tripoint.kitware.com User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 In-Reply-To: <2242837.lDbo80ytWE@tjmaciei-mobl4> X-Original-Sender: mwoehlke.floss@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of gclcip-std-proposals@m.gmane.org designates 80.91.229.3 as permitted sender) smtp.mailfrom=gclcip-std-proposals@m.gmane.org; dmarc=fail (p=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org 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:20723 Archived-At: On 2015-09-23 02:06, Thiago Macieira wrote: > On Tuesday 22 September 2015 10:38:58 joewoodbury@gmail.com wrote: >> Thus if I wrote >> >> int val = connection ?: 5; >> >> your solution wouldn't work. > > Assuming that connection was a pointer here, you'd get an error about > assigning a pointer to an integer. > > The ?: syntax with the missing second operand already has a precedent to mean > a repeat of the first operand. Therefore, the above reads: > > int val = connection ? connection : 5; > > However, I would like to see the syntax standardised. When you're dealing with > C code that returns error conditions, this is useful: > > ErrorCode err = some_function(); > err = err ?: some_other_function(); > err = err ?: some_third_function(); err || err = some_other_function(); :-) (I've actually written code like that. Pedantically, I think it was of the form 'success && ...', but same idea...) > I'm not going to ask for, but it would be nice to have > > err ?:= some_function(); ....or, as in my reply, '?!(err) = some_function();'; tacking '?' / '?:' / '?!' on to other operator tokens makes me nervous ;-). I too think it would be nice to have, but don't see it being sufficiently nice as to actually be accepted as a proposal. Actually... hmm... #define iff(var) \ for (auto _guard = true; _guard;) \ for (auto&& _var = var; _guard && bool{_var}; _guard = false) \ _var #define ifn(var) \ for (auto _guard = true; _guard;) \ for (auto&& _var = var; _guard && !bool{_var}; _guard = false) \ _var iff(object)->method(); ifn(err) = some_function(); -- Matthew -- --- 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/. .