220 5232 article Path: news.gmane.org!not-for-mail From: Jonathan Wakely Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Teachability problems with std::move Date: Wed, 26 Jun 2013 05:08:41 -0700 (PDT) Lines: 109 Approved: news@gmane.org Message-ID: References: <73cad38f-c1b6-4ce3-bfc1-e4a660dbb638@isocpp.org> <09ec0612-ac10-48fb-a186-bd3c200bd5fe@isocpp.org> <20f56505-2fba-4041-9d81-26088e67dc5d@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_451_27735288.1372248521655" X-Trace: ger.gmane.org 1372248525 22664 80.91.229.3 (26 Jun 2013 12:08:45 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 26 Jun 2013 12:08:45 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCMONUNYS4IRBSVTVOHAKGQEGIJJN4Q@isocpp.org Wed Jun 26 14:08:44 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oa0-f71.google.com ([209.85.219.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UroWi-0004v8-8l for gclcip-std-proposals@m.gmane.org; Wed, 26 Jun 2013 14:08:44 +0200 Original-Received: by mail-oa0-f71.google.com with SMTP id k14sf22106615oag.2 for ; Wed, 26 Jun 2013 05:08:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-beenthere:date:from:to:message-id:in-reply-to:references:subject :mime-version:x-original-sender:reply-to:precedence:mailing-list :list-id:x-google-group-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type; bh=odmNBnQNLKqnojzM8IweNEqNaqp3VuPfIAogsskf08g=; b=dbGQmGgdPVu86HIgxtju59SANiBATMTE0/VWTqO9xfNql5larVaPCcPDYog4ZMXD0y VtiOmIHFZPthLy9IEsEyh7n34g2r/vdZEXSQQFE/G/A5As49n2WPFBo6Uz+JQF3W+1FL AXETEIt28qV+KcJK6mK5c9EloTCletZ0q+6nG9vOmz9iQPPeSriGyw8EI4S9CHFNRDUl Mb2cSDuVQHsRPt3qJwdrLR16w/xHFZJNcxNsgpmqBgZCzGuyFHIhPTHQ/Rczd82tGMig gudO+j1FXs+OUJxeX8tAxIJ+29Px/0lm83TuI5005Q1vX53eUDFuYm4mjTHQNRJdpNpt 5rpg== X-Received: by 10.182.230.169 with SMTP id sz9mr617840obc.48.1372248523217; Wed, 26 Jun 2013 05:08:43 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.233.131 with SMTP id tw3ls62810obc.70.gmail; Wed, 26 Jun 2013 05:08:42 -0700 (PDT) X-Received: by 10.182.114.228 with SMTP id jj4mr3108obb.8.1372248522152; Wed, 26 Jun 2013 05:08:42 -0700 (PDT) In-Reply-To: X-Original-Sender: cxx@kayari.org 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:5232 Archived-At: ------=_Part_451_27735288.1372248521655 Content-Type: text/plain; charset=ISO-8859-1 On Wednesday, June 26, 2013 12:10:58 PM UTC+1, Mikhail Semenov wrote: > > > Coming back to the original topic, are you really suggesting the code > above is the ideal form for teaching when to use std::move and when > not > to? I think "return result;" is much simpler. > > If you have to convert from std::unique_ptr to std::unique_ptr Foo> > the following code *WON'T COMPILE*; > *return result;* > > *Try it in your compiler!* > > My point is that if you have to convert (from std::unique_ptr to > std::unique_ptr) write it explicitly: > > *return std::unique_ptr(std::move(result));* > > If you don't have to convert (you use the same unque_ptr types) than yes write > as you said: > ** > *return result*. > > Yep, I know, I was referring to Geoffrey's suggestion to change that rule in the first post in this thread: "It would be clear anyway with Geoffrey's suggestion". Apologies for trying to discuss the thread topic ;) -- --- 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_451_27735288.1372248521655 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

On Wednesday, June 26, 2013 12:10:58 PM UTC+1, Mikhail Semenov wrot= e:
> Coming back to the original topic,= are you really suggesting the code above is the ideal form for teaching wh= en to use std::move and when > not to?  I think "return result;" is= much simpler.
 
If you have to convert from std::unique_ptr<Foo> to std:= :unique_ptr<const Foo>
the following code WON'T COMPILE= ;
return result;
 
Try it in your compiler!
 
My point is that if you have to convert  (from std::uniqu= e_ptr<Foo> to std::unique_ptr<const Foo>) write it explicitly:<= /font>
 
return std::unique_ptr<const Foo>(std::move(result));=
 
If you don't have to convert (you use the same= unque_ptr types) than yes write as you said= :
 
return result.


Yep, I = know, I was referring to Geoffrey's suggestion to change that rule in the f= irst post in this thread: "It would be clear anyway with Geoffrey's suggest= ion".   Apologies for trying to discuss the thread topic ;)

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