220 8322 <68012381-8af4-4d62-a5a4-912c454fba96@isocpp.org> article Path: news.gmane.org!not-for-mail From: fmatthew5876@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Proposal: Default swap operation Date: Tue, 31 Dec 2013 18:05:18 -0800 (PST) Lines: 196 Approved: news@gmane.org Message-ID: <68012381-8af4-4d62-a5a4-912c454fba96@isocpp.org> References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_4695_25600600.1388541918666" X-Trace: ger.gmane.org 1388541915 28475 80.91.229.3 (1 Jan 2014 02:05:15 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 1 Jan 2014 02:05:15 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDELF54RTIGRBX7PRWLAKGQERGH7XIA@isocpp.org Wed Jan 01 03:05:23 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vc0-f198.google.com ([209.85.220.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VyBBR-0003Xx-4K for gclcip-std-proposals@m.gmane.org; Wed, 01 Jan 2014 03:05:21 +0100 Original-Received: by mail-vc0-f198.google.com with SMTP id lf12sf14064438vcb.1 for ; Tue, 31 Dec 2013 18:05:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe :content-type; bh=PbnQSUXkGCbSX7drm2zotMQ7Rzv/ZcwnsnKEWk1q4nI=; b=eO/twvZ9gZ33F/bYiwxeIc9YDUH9vmM2S/dbrF6PjdHIuDNGpuHp2v3IBsWUbRK0tf +LTdIMQ2ubK2D7qIJR81Ef8im5q+BsjkIb5GmsDj1jxHJF/0G5hSdNVrSfgmulUxWk7d zBWfVPDq8/edkPSkkj222wKsqEH/9zxlpOBQYHOS6lBXlvKwZKPIOO/f53GmwsalNHiT xnGkszxVqpYM1E1gdDkPIR01uHoWsqYvErClpjMQvN+lw1Sm6BNKERyyxS2pmM5ew7nu QlQExu0+lklhetfO1JhMJNSPuqgaftKDBWiHV1o11+sdlDFP0FpM/Soc502XVnmUcTNk sksw== 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:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type; bh=PbnQSUXkGCbSX7drm2zotMQ7Rzv/ZcwnsnKEWk1q4nI=; b=MWqpcuBD/SzypIIFIE98eRIhZySzVmluFFdBBM1PEKm3RFi9hQ243GU3LTRLfapzdQ ANoHrsjTSmyrEqc1EWG34QLNdxoX+gakyDtZvybK6ig3zVr/jypav6TCQSzV5bF9VPWk W/vyDXfWZ0GTdmbB9xvOvGbbn7R0hku1/An2/9+yL+4TWU2l63C91jr5OoEG6VKRIUkX g68mH54enngs+c+jpswldglHwPnGr1S7mSCMAVcs+BR7OEMFfMeKvq8XeNmek1sQPqMV 0AkN/FnaO7Xzo/2jqIU4iUHDVeCMj010wb/OEkLboWFFUQvEVapZJmbuTGO8YFlB93EZ +pnQ== X-Gm-Message-State: ALoCoQkXcJvTzkwfDF/Is0Ep3ujqeaC9NOIKQkSx6LiduIuMYF+YJ/A1nsB3diMjs1eiUAFIqU6k X-Received: by 10.58.181.69 with SMTP id du5mr30568546vec.7.1388541920057; Tue, 31 Dec 2013 18:05:20 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.48.82 with SMTP id j18ls4053659qen.49.gmail; Tue, 31 Dec 2013 18:05:19 -0800 (PST) X-Received: by 10.49.101.73 with SMTP id fe9mr1197qeb.6.1388541919355; Tue, 31 Dec 2013 18:05:19 -0800 (PST) In-Reply-To: X-Original-Sender: fmatthew5876@gmail.com 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:8322 Archived-At: ------=_Part_4695_25600600.1388541918666 Content-Type: text/plain; charset=ISO-8859-1 On Tuesday, December 31, 2013 8:53:46 PM UTC-5, Billy O'Neal wrote: > > I don't think this is a good idea -- if a type is going to provide swap, > normally it must do so in a non-throwing way. I'd worry that people would > just add it in without thinking only to break normal assumptions of what > swap does. > Maybe, but the defaulted swap calls swap for the members which itself should already have the non-throwing rule. If your swap has to do something special that might throw, you would have to write it yourself anyway. > > The other issue here is that "using std::swap" would require including > ... > Implementing swap yourself in this way requires the same. > > > Billy O'Neal > https://github.com/BillyONeal/ > http://stackoverflow.com/users/82320/billy-oneal > Malware Response Instructor - BleepingComputer.com > > > On Tue, Dec 31, 2013 at 5:42 PM, >wrote: > >> Writing swap() is one of those boilerplate kinds of things that is >> usually trivial but annoying (and error prone when you change data members >> but forget to update swap()). >> >> Why not allow this: >> >> class Foo { >> public: >> void swap(Foo& f) = default; >> private: >> int a; >> Bar b; >> float c; >> Baz* d; >> }; >> >> Which would be the equivalent of this: >> >> void Foo::swap(Foo& f) { >> using std::swap; >> swap(a, f.a); >> swap(b, f.b); >> swap(c, f.c); >> swap(d, f.d); >> } >> >> Any reason this wouldn't make it as a proposal? >> >> -- >> >> --- >> 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-proposal...@isocpp.org . >> To post to this group, send email to std-pr...@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/. ------=_Part_4695_25600600.1388541918666 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

On Tuesday, December 31, 2013 8:53:46 PM UTC-5, Billy = O'Neal wrote:
= I don't think this is a good idea -- if a type is going to provide swap, no= rmally it must do so in a non-throwing way. I'd worry that people would jus= t add it in without thinking only to break normal assumptions of what swap = does.


The other issue here is that "using std::swap" would require= including <algorithm>...

Implementing swap yourself in this way requires the same.
 =
 

Billy O'Neal
Malware Response Instructor - BleepingComputer.com


On Tue, Dec 31, 2013 at 5:42 PM, <fmatth...@gmail.com> wrote:
Writing swap() is one of those boilerplate kinds of things= that is usually trivial but annoying (and error prone when you change data= members but forget to update swap()).

Why not allow thi= s:

class Foo {
  public:
  &= nbsp; void swap(Foo& f) =3D default;
  private:
    int a;
    Bar b;
  &nbs= p; float c;
    Baz* d;
};

Which would be the equivalent of this:

void Foo::swap(Foo& f) {
  using std::swap;
=   swap(a, f.a);
  swap(b, f.b);
  swap(c= , f.c);
  swap(d, f.d);
}

Any reason this w= ouldn't make it as a proposal?

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Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposal= s/.

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