220 32379 <5f24e72e-6f21-4b99-84d7-053c940e66a1@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Jakob Riedle Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: =?UTF-8?B?UmU6IFtzdGQtcHJvcG9zYWxzXSBSZTogQWRkaW5nIHRoZSBLZXl3b3JkIOKAnGludGVyZg==?= =?UTF-8?B?YWNl4oCdIGluIEMrKw==?= Date: Wed, 10 May 2017 00:25:57 -0700 (PDT) Lines: 177 Approved: news@gmane.org Message-ID: <5f24e72e-6f21-4b99-84d7-053c940e66a1@isocpp.org> References: <9ee212eb-4037-40c4-94c3-57a9a170a4c3@isocpp.org> <1765502.4y06pMOS3s@tjmaciei-mobl1> <20170509050057.GA1227@noemi> <6edad2ff-ea7e-4b26-bf65-0311e63e7633@isocpp.org> <31ce0dab-a80e-4356-a63c-a51ffb56b168@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_4694_615182131.1494401157979" X-Trace: blaine.gmane.org 1494401160 30287 195.159.176.226 (10 May 2017 07:26:00 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 10 May 2017 07:26:00 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCX2XNFO6MPRBB4BZPEAKGQEORQDIVI@isocpp.org Wed May 10 09:25:56 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oi0-f71.google.com ([209.85.218.71]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1d8M0R-0007ky-B2 for gclcip-std-proposals@m.gmane.org; Wed, 10 May 2017 09:25:55 +0200 Original-Received: by mail-oi0-f71.google.com with SMTP id c132sf24698299oia.6 for ; Wed, 10 May 2017 00:26:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :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=eOkJhDPDCAAXOdkAl7yi5I1KOrdSFTWOKAyUI9Kivgw=; b=TsLiazr8eTXeFOQbUIcvqYZZ09OXnuNpLtAg3p4ZlvBq4oD9ObI4tS3m1RqiZMexSS nqKW/G6lqjVnnO4JEAAgp+138RUQj2/LSTZiimuvFIahJpfWFiomHUC00Gr506Dsc7wn 3WJ2BykUQ7d0QlkxHU23/cjwk3y3y928hX5hyAHi3yCWRPgXJbjjMbcQvl03AqNhq2YN 7LTu+vws1lnTjIEg+l8lei+CWGiqdUm6kbl/e2aB0G3l7x7y/YqxHrzyqx6gKhshUdOG SvFgwTtOdxR/n4EC9Jl8/T/4fCtLSbJ3zdS7um67IKNSTxtprNFM0RBuetOL2Q8kwgKm 3olA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :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=eOkJhDPDCAAXOdkAl7yi5I1KOrdSFTWOKAyUI9Kivgw=; b=M2k/a8OrWKMYU3FuyZ1JpIepvmcuv8ikxN1ENkhjEVsyZjkE446oVWwamdFzXrXNIg 8XfaURNHj7P2S7a1ju4453L0h86lYORfQ99OZselew7rpYasIqwiafXhKzBMRyRr034y EusmCPXlSFiX005XmfbA50+TwRT1OSituLS8TKZ5B8Qte3R+L/VUMfgVkGDQhNeLD/QY 3m+YZQZ6AyNDJoyMZFFvO1u2D5MIQChcey4WALf/tCYqNg6ox4/h9X3dJ/RpvyLv9hsU R07w+qMfuRvMnY3FgOJCiWVHj+bD+9RVo6gy5JwTMADlZIb6ykkw3GvBAwh5gC30WBZe 01QQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; 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:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=eOkJhDPDCAAXOdkAl7yi5I1KOrdSFTWOKAyUI9Kivgw=; b=T+jZHN+T/OD8hft/rpDr2S6GHZ7zrJsejWMkGD6+gjZDrGExFSr+OJ2qKOEHfV7Zc8 /R6z7oLH35ifXNdkpcXsAuoXsxqpskHpMfuKOk1mmB0g/alXVq7jbv3ytgyfUlcvW0jA G6eyvPlqRgIMAT0L9Sa4s8irqViZxAFCY5l+vDk+0NI6Ibhet7uiWfLfcV+5eDnzkb98 IzaoQb/PzM7k7xlbLuqAW38W343iXe0hWTg7jUYhULOlEucQ6wgnQhXqqxxmIXWRccOj 8dp5oJN4DO7INYqEBbZ2cYiK3JtWRoiDUrhuuW57D7AFheGSpc6le/I0Kcs9qFmzp7S3 Z5mA== X-Gm-Message-State: AODbwcA+NvygrT2MJg+Oab+6cPyAdgwxnm5Pr1KZyCKbXWEa5u3GgG/8 QqDL2WF4s6lqaQ== X-Received: by 10.157.45.50 with SMTP id v47mr2101728ota.105.1494401160545; Wed, 10 May 2017 00:26:00 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.23.8 with SMTP id i8ls2167009ota.11.gmail; Wed, 10 May 2017 00:25:58 -0700 (PDT) X-Received: by 10.157.35.104 with SMTP id k37mr89639otd.14.1494401158752; Wed, 10 May 2017 00:25:58 -0700 (PDT) In-Reply-To: <31ce0dab-a80e-4356-a63c-a51ffb56b168@isocpp.org> X-Original-Sender: jakob.riedle@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:32379 Archived-At: ------=_Part_4694_615182131.1494401157979 Content-Type: multipart/alternative; boundary="----=_Part_4695_1471380589.1494401157980" ------=_Part_4695_1471380589.1494401157980 Content-Type: text/plain; charset="UTF-8" > > I was thinking about the same issue before posting this solution, because > the "interfaces" seems to have violated the "single responsibility > principle". Thus, the conversion is only allowed when the concrete > implementations are passed "by value" (as a copy), whose ownership/lifetime > shall be managed within the "interface" system. > Thank you! Oh, that is so true, I didn't realize that before! So what be basically want is this? std::function f1 = /**/; std::function f2(); const volatile std::function f3 = /**/; Callable c1 = f1; // This copies f. Internally, an std::unique_ptr as handle is needed. Callable& c2 = f1; // This references f. internally, the abstract class generatedfor Callable needs a '&' handle. Callable&& c3 = f2(); // Internally uses '&&' as handle. const volatile Callable& c4 = f3; //Internally 'const &' as handle. // and so on... At least now, Dynamic Concepts need to be a language feature, since the reference/const/volatile specification needs to be internalized into the implicit abstract class generation. Cheers, Jakob @Minxing Wang: Could you please not cite whole posts in your answers, this elongates the thread immensely :) -- 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. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/5f24e72e-6f21-4b99-84d7-053c940e66a1%40isocpp.org. ------=_Part_4695_1471380589.1494401157980 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
= I was thinking about the same issue before po= sting this solution, because the "interfaces" seems to have viola= ted the "single responsibility principle". Thus, the conversion i= s only allowed when the concrete implementations are passed "by value&= quot; (as a copy), whose ownership/lifetime shall be managed within the &qu= ot;interface" system.
<= font face=3D"georgia, serif">Thank you!

<= div>Oh, that is so true, I didn't realize that before!

So what be basically want is this?
std::function= <void()> f1 =3D /**/;
std::function<void(= )> f2();
const volatile std::function<void()> f3 =3D /**/;

Callable<void()> c1 =3D f1; // This= copies f. Internally, an std::unique_ptr as handle is needed.
Callable<void()>& c2 =3D f1; /= / This references f. internally, the abstract class generatedfor Callable n= eeds a '&' handle.
Callable<void= ()>&& c3 = =3D f2(); // Internally uses '&= ;&' as handle.
const volatile= Callable<void()>& c4 =3D f3; //Internally 'const &' as handle.
// and so on...

At least now, Dynamic Concepts need to be a la= nguage feature, since the reference/const/volatile specification needs to b= e internalized into the implicit abstract class generation.
=C2= =A0
Cheers,
Jakob

@Minxing Wan= g: Could you please not cite whole posts in your answers, this elongates th= e thread immensely :)

--
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