220 20623 <4c3e2ee7-2159-4e93-a439-7d5c94c38c9c@isocpp.org> article Path: news.gmane.org!not-for-mail From: joewoodbury@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Null -conditional and -coalescing operators Date: Tue, 22 Sep 2015 10:03:47 -0700 (PDT) Lines: 81 Approved: news@gmane.org Message-ID: <4c3e2ee7-2159-4e93-a439-7d5c94c38c9c@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_3284_1043426421.1442941427135" X-Trace: ger.gmane.org 1442941431 2242 80.91.229.3 (22 Sep 2015 17:03:51 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 22 Sep 2015 17:03:51 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCBMHLUN7EEBB5ETQ2YAKGQET7DSHFA@isocpp.org Tue Sep 22 19:03:51 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk0-f198.google.com ([209.85.220.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZeQyr-0006sm-Tl for gclcip-std-proposals@m.gmane.org; Tue, 22 Sep 2015 19:03:50 +0200 Original-Received: by qkey1 with SMTP id y1sf19416623qke.0 for ; Tue, 22 Sep 2015 10:03:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:subject:mime-version:content-type :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=WS79kbuHmeT4hjzsIrt9MdrDPDxmVQGCacGw8URBLPA=; b=gQjJTllNFlM/h2sTbhiDtkqt5s1VE3zQM8VUEoVBwDOe4i+2O9pZ/K9g8XPR/jaO2O KMBIbBmtaasK2zgiXAnW9xCSBhj7jEm8Yi3NUPHal9TQp+xiB7Qw0eqrcho4QJ2pIlAn 6vWjVgsiGBm/WGdsmr6CIBl2Prng1PU2YFE/rWgOvnFX20MrhpeQoObhreU3+9sVZRtB Qhhy1kYKKd1NlxMek4DB+HbF7YRP2IC8Ai9zxdAiqaX58gi+L0OtRegfaqaV7wSu+AOm QDt7NGSnagmRsAp+miWvsBK49C7OGMSgk1jmP/CYG1TQ40JoOa4tKa20W/hanhVtmPs2 o3NQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:message-id:subject:mime-version :content-type: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=WS79kbuHmeT4hjzsIrt9MdrDPDxmVQGCacGw8URBLPA=; b=AT5zrafbN1YzUo7uc7PbubfcDP7yvyiZRFcHBdjTM9vkzMe16wl9vxAnU/Jo5js4ZJ PLhLEtt3bg3sksOBSOklQMbSLNdsZ/OTL2uJWw7kniEj03q73dJaiFrzKPmNYPT/oSbb ZzYDqTXK0P/QkYxIaW1xumoNPis7JcTICPzLxG71PE4A+eYThA6zbASZYKEM3kX07M79 wO3NCnUI4aRjWJLBwbNcPnuJcBmgSiXxcyk/PqZccG5B+sHBnvR485Rhh/xn0uX1Oog7 fvkPxkeouLeauR4fWcC/gRbuxnvdIl7rxU6sHDcSFF/+aEeT/nucDdmJcsIfYrU8rGSv YHRQ== X-Gm-Message-State: ALoCoQloCdjFswuopdNVr6HnuhzvmdPZF7tO04me8LO633WrEjrQcbral/y7+cMK4ClHlJ/Vm6ne X-Received: by 10.129.40.83 with SMTP id o80mr22069699ywo.27.1442941428831; Tue, 22 Sep 2015 10:03:48 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.132.164 with SMTP id o36ls203997ioi.64.gmail; Tue, 22 Sep 2015 10:03:47 -0700 (PDT) X-Received: by 10.50.79.136 with SMTP id j8mr204573igx.16.1442941427925; Tue, 22 Sep 2015 10:03:47 -0700 (PDT) X-Original-Sender: joewoodbury@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:20623 Archived-At: ------=_Part_3284_1043426421.1442941427135 Content-Type: multipart/alternative; boundary="----=_Part_3285_434060113.1442941427135" ------=_Part_3285_434060113.1442941427135 Content-Type: text/plain; charset=UTF-8 Checking for null and then doing one thing is a common task. null-conditional and null-coalescing operators would be a nice solution. For example, given the following pointer: unique_ptr connection; This may happen: if (connection) { connection->sendMessage(msg); } A nice alternative would be: connection ?: connection->SendMessage(msg); I've had situations where if anything resolves to false on the left, this ?: would be useful. Or even better, to carry the concept forward: connection?->SendMessage(msg); Likewise: bool success = connection ?: false; -- --- 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/. ------=_Part_3285_434060113.1442941427135 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Checking for null and then doing one thing is a common tas= k. null-conditional and null-coalescing operators would be a nice solution.=

For example, given the following pointer:

=C2=A0=C2=A0=C2=A0= unique_ptr<Connection> connection;

This may happen:

= =C2=A0=C2=A0=C2=A0 if (connection)
=C2=A0=C2=A0=C2=A0 {
=C2=A0=C2=A0= =C2=A0 =C2=A0=C2=A0=C2=A0 connection->sendMessage(msg);
=C2=A0=C2=A0= =C2=A0 }

A nice alternative would be:

=C2=A0=C2=A0=C2=A0 conn= ection ?: connection->SendMessage(msg);

I've had situations w= here if anything resolves to false on the left, this ?: would be useful.
Or even better, to carry the concept forward:

=C2=A0=C2=A0=C2= =A0 connection?->SendMessage(msg);

Likewise:

=C2=A0=C2=A0= =C2=A0 bool success =3D connection ?: false;


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