220 11800 <072cf8b4-4c74-438e-9999-0aab13bf3182@isocpp.org> article Path: news.gmane.org!not-for-mail From: tomaszkam@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: N4078: Rvalue reference overloads for value() method returns object by value Date: Thu, 10 Jul 2014 02:29:17 -0700 (PDT) Lines: 84 Approved: news@gmane.org Message-ID: <072cf8b4-4c74-438e-9999-0aab13bf3182@isocpp.org> References: <4DA018C3-2327-4F55-B7F8-7988EC7B789A@gmail.com> <1a858a77-310b-4591-aaf5-960c40d9f5fc@isocpp.org> <66AF41C1-CB37-4311-98EA-D47DBC6068DC@gmail.com> <66c38b61-7a95-4ace-b34f-2346bb334fb9@isocpp.org> <6F4B3C72-9962-48DC-8527-0C89EA1B9710@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_82_21799650.1404984557394" X-Trace: ger.gmane.org 1404984571 28031 80.91.229.3 (10 Jul 2014 09:29:31 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 10 Jul 2014 09:29:31 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDNPVXXG6IGBB3VZ7GOQKGQEPWKAFZY@isocpp.org Thu Jul 10 11:29:22 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pa0-f69.google.com ([209.85.220.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1X5AfI-0003CE-MX for gclcip-std-proposals@m.gmane.org; Thu, 10 Jul 2014 11:29:21 +0200 Original-Received: by mail-pa0-f69.google.com with SMTP id kq14sf58266840pab.0 for ; Thu, 10 Jul 2014 02:29:19 -0700 (PDT) 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=EQ8O3Wx5s3tWLNpDaQqsbjZdL6E7eJU0X8SyDFJq9g0=; b=LcIb0kLMCZZ3xYHmz+JDiHWPUly7WgtJ3bkccwBUORmKLZZnMfLFXaQXz0lQtwGr0k UjP4y6wTvhVGWrzC4lkcako9hSRpbTAeJo5EMgIH1n+iPOdVf4iDS4ACHMhUpowW7BOs vsL3KAzE1Ui9rOYXAG2oLgjU6L56SA17HN9+Twf2WyKyYRTPmjlUo1d93hhXdUiA45LV gf9sjPgxxRd3McN1MqlwZw98AsTqkTdvZ7/rmeP8X/qMUPXadJAF9eG6oOPa+QSYOBHU OzNk8ZtRPW3ofJhf7wE1xFLHNcEqCqD9wiJDDlKW9swk9/Slffv0fb+PHr7YPdM3UjhP a93Q== 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=EQ8O3Wx5s3tWLNpDaQqsbjZdL6E7eJU0X8SyDFJq9g0=; b=EgfQ/8jf3rWoQY+whwlFybMyCQ8RIxv28kDfqYaimjKSSx/cTmJcaVDtJjUCtjA/AQ /HabFYgcrIgL4mp3w7pO/BR+EBN3+GDXIx6WQmqdmjeg3D8TlSCMfr4TaR8vVkIguA2R UnRXdkujSN1MBoA4MMrHldiTwQHANcIvcAG0p6QrKhxQd3QfgxX9549PxFrmAmm+URfm Of+PEU79qk+Efo1dpStwG1dKgRSZNjxbUuKNXb/SAhp7s+/oFgx45xTley3iHdm/zZV7 SF28encisGSA/hi7shbDhRR3KJi1NOW4nJvJP5f7cR1AC1sUg9WkjLPy1dQTpmxlnZNV gnNw== X-Gm-Message-State: ALoCoQmIqDdRpeusL8vldGYfSnOSI4jnAKfYGPs/EZbXqvqUPhAsoFXZ2vxf4eSz//nNN0bqU7Zq X-Received: by 10.66.182.130 with SMTP id ee2mr8443270pac.37.1404984559209; Thu, 10 Jul 2014 02:29:19 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.109.137 with SMTP id hs9ls22312obb.86.gmail; Thu, 10 Jul 2014 02:29:18 -0700 (PDT) X-Received: by 10.182.236.37 with SMTP id ur5mr147628obc.19.1404984558140; Thu, 10 Jul 2014 02:29:18 -0700 (PDT) In-Reply-To: <6F4B3C72-9962-48DC-8527-0C89EA1B9710@gmail.com> X-Original-Sender: tomaszkam@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:11800 Archived-At: ------=_Part_82_21799650.1404984557394 Content-Type: text/plain; charset=UTF-8 To be clear, the value function definied in the following text has following definition before the change: T& value(); T const& value() const; This function depsite the name does not return anything by value and haser the same relaction with operator*, like operator[] with at in vector. In the paper that I mentonied in original post following overloads was added: T& value() &; T const& value() const &; T value() &&; T value() const &&; Which makes following invoaction f(expr.value()) where takes T by const& and expr is value of type optional, introducing has additonal possibly-copy dependin on expr being lvalue or r-value. And makes using optional in generic context when perfect forwardin us used a pain. I propose to set of methods to look like: T& value() &; T const& value() const &; T&& value() &&; To achieve consistency with std::get function or even simple meber acces with procudes same cateogry value for subobject. If the original set of the methods was: T value() const; I would arrge tthe the new function should be declared as: T value() const; T value() &&; But this is not -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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To be clear, the value function definied in the following = text has following definition before the change:
  T& value();<= br>  T const& value() const;
This function depsite the name doe= s not return anything by value and haser the same relaction with operator*,= like operator[] with at in vector.

In the paper that I mentonied in= original post following overloads was added:
  T& value() &am= p;;
  T const& value() const &;
  T value() &&a= mp;;
  T value() const &&;
Which makes following invoact= ion f(expr.value()) where takes T by const& and expr is value of type o= ptional<T>, introducing has additonal possibly-copy dependin on expr = being lvalue or r-value. And makes using optional in generic context when p= erfect forwardin us used a pain. I propose to set of methods to look like:<= br>  T& value() &;
  T const& value() const &= ;
  T&& value() &&;
 To achieve consistency= with std::get function or even simple meber acces with procudes same cateo= gry value for subobject.

If the original set  of the methods wa= s:
  T  value() const;
I would arrge tthe the new function = should be declared as:
  T  value() const;
  T  v= alue() &&;
But this is not

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