220 22641 article Path: news.gmane.org!not-for-mail From: "'Jeffrey Yasskin' via ISO C++ Standard - Future Proposals" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Post-assignment operator Date: Sat, 14 Nov 2015 10:07:13 -0800 Lines: 113 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=089e01183eecccb8270524840bbf X-Trace: ger.gmane.org 1447524457 11556 80.91.229.3 (14 Nov 2015 18:07:37 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 14 Nov 2015 18:07:37 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDDM34EO6QDRBVHQTWZAKGQEJFSE3RY@isocpp.org Sat Nov 14 19:07:23 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pa0-f72.google.com ([209.85.220.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZxfEM-0004Ov-73 for gclcip-std-proposals@m.gmane.org; Sat, 14 Nov 2015 19:07:19 +0100 Original-Received: by padhz14 with SMTP id hz14sf122441722pad.1 for ; Sat, 14 Nov 2015 10:07:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp_org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type: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=DJ3Bz0PgGHUrvIIRL5OyMC+40eDGz/hTqKk3Ey3y9N4=; b=aT2EXuXvzGMY6v4zocJlg7xDCeGNZYAo55qT+61GsoLbzxlePIeE8Y8UqGPuTuhFSm 46P9KwsCR9dpZWwbjh6g7R/nePvSG9+H86FP7/0ds8X9cGt8C2RCslii4eNnpDw259D/ sW2YroRgiFA7qjTeHDcs7Y4ML33RFRre9Q9THuIvYsc7i3pIFB+PweAnB1H9OXkk6sCe NvDH09qMyHoiZPG1W9bNxgXT0ye8pF+XpK7Hx9+eKa7hT7+PxqCEgiLZ4H02fBHyrr03 BBhi9PUhAvpmYricy0CRVPRWF4/3PCPqd6ZYL4y0h0MEdL9W84mYaAK5vDOQQGF/1ZWs ybfA== 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:date :message-id:subject:from:to:content-type: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=DJ3Bz0PgGHUrvIIRL5OyMC+40eDGz/hTqKk3Ey3y9N4=; b=U9oK8SBdVTubZV6J3etM/r16l3MUq3lAPojclfi66/OptxWmvk/PRcPQVDf1L5gDgp qX1A8y+EWEkt707X27NMrgCXPwMInvmOKTljBynT9ObQXCdoDp+KOYa52vHOuYMBFSiT BLUdjIsElQl+Pz7AjA/DPJ0+rjoqcwV+bGtznaiD3we87npL/nXh8ZFfAXv43NaTYLh1 qQPsQlAtE/8q3YIklUDsh5gU8vcwb5mRro3Y4IWAKDgDl1BcR6vXMNZfQuNuWd87Y+93 HBsf4WZ4Zx9xSYULbT05FrqmowhYrU04Y/+TZCkmjBlX7+Ecr7ba3T5Tg/Q9xvT9RaU/ q4BA== X-Gm-Message-State: ALoCoQnPsgxKvtywrAU6/2R+E228s+0oG/cog95JigpH5JB2dkkOZgVoMfmBZ9IwKf7o+tJsra5Q X-Received: by 10.67.30.227 with SMTP id kh3mr22640029pad.6.1447524437190; Sat, 14 Nov 2015 10:07:17 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.79.130 with SMTP id j2ls520387igx.34.canary; Sat, 14 Nov 2015 10:07:16 -0800 (PST) X-Received: by 10.50.78.101 with SMTP id a5mr8995385igx.42.1447524436268; Sat, 14 Nov 2015 10:07:16 -0800 (PST) Original-Received: from mail-ig0-x234.google.com (mail-ig0-x234.google.com. [2607:f8b0:4001:c05::234]) by mx.google.com with ESMTPS id 10si13356607igq.45.2015.11.14.10.07.16 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 14 Nov 2015 10:07:16 -0800 (PST) Received-SPF: pass (google.com: domain of jyasskin@google.com designates 2607:f8b0:4001:c05::234 as permitted sender) client-ip=2607:f8b0:4001:c05::234; Original-Received: by igbxm8 with SMTP id xm8so33299817igb.1 for ; Sat, 14 Nov 2015 10:07:15 -0800 (PST) X-Received: by 10.50.171.194 with SMTP id aw2mr9248274igc.83.1447524435776; Sat, 14 Nov 2015 10:07:15 -0800 (PST) Original-Received: by 10.64.240.51 with HTTP; Sat, 14 Nov 2015 10:07:13 -0800 (PST) Original-Received: by 10.64.240.51 with HTTP; Sat, 14 Nov 2015 10:07:13 -0800 (PST) In-Reply-To: X-Original-Sender: jyasskin@google.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of jyasskin@google.com designates 2607:f8b0:4001:c05::234 as permitted sender) smtp.mailfrom=jyasskin@google.com; dkim=pass header.i=@google.com; dmarc=pass (p=REJECT dis=NONE) header.from=google.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: , X-Original-From: Jeffrey Yasskin Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:22641 Archived-At: --089e01183eecccb8270524840bbf Content-Type: text/plain; charset=UTF-8 Check out std::exchange(). On Nov 14, 2015 9:32 AM, "Lingxi Li" wrote: > I frequently find code similar to the following: > > delete ptr; > ptr = nullptr; > close(fd); > fd = -1; > > Why don't we just introduce a post-assignment operator that performs the > assignment > but returns the previous value of the left-hand-side, just like the > post-increment/decrement > operator? Denote such an operator by `.=`, the above code snippet could be > simplied to > > delete ptr .= nullptr; > close(fd .= -1); > > -- > > --- > 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/. --089e01183eecccb8270524840bbf Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

Check out std::exchange().

On Nov 14, 2015 9:32 AM, "Lingxi Li" &= lt;lilingxi.cs@gmail.com> w= rote:
I frequently find code similar to the following:

delete ptr;
ptr =3D nullptr;
close(fd);
fd =3D -1;

Why don't we just introd= uce a post-assignment operator that performs the assignment
but returns = the previous value of the left-hand-side, just like the post-increment/decr= ement
operator? Denote such an operator by `.=3D`, the above code snippe= t could be simplied to

delete ptr <= span style=3D"color:#660">.=3D nullptr;
close(fd .=3D -1);

--

---
You received this message because you are subscribed to the Google Groups &= quot;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/gro= up/std-proposals/.

--

---
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+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/<= /a>.
--089e01183eecccb8270524840bbf-- .