220 11106 <0e4e74ec-09f0-4102-b46b-589949a45519@isocpp.org> article Path: news.gmane.org!not-for-mail From: tomaszkam@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: N4015: A proposal to add a utility class to represent expected monad Date: Fri, 6 Jun 2014 02:43:59 -0700 (PDT) Lines: 87 Approved: news@gmane.org Message-ID: <0e4e74ec-09f0-4102-b46b-589949a45519@isocpp.org> References: <94ded66f-1c50-47b9-8a04-b83805443da9@isocpp.org> <5380804B.80607@wanadoo.fr> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_178_31535809.1402047839664" X-Trace: ger.gmane.org 1402048207 15287 80.91.229.3 (6 Jun 2014 09:50:07 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 6 Jun 2014 09:50:07 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDNPVXXG6IGBBYE2Y2OAKGQEMKYWRKQ@isocpp.org Fri Jun 06 11:50:00 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f200.google.com ([209.85.213.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Wsqgr-0002Fc-Sg for gclcip-std-proposals@m.gmane.org; Fri, 06 Jun 2014 11:44:02 +0200 Original-Received: by mail-ig0-f200.google.com with SMTP id l13sf1884746iga.11 for ; Fri, 06 Jun 2014 02:44:00 -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=KGBSJepcknEMLj2k6SdMfRjwwubO1aNnYzxXIxEr/uc=; b=Kl6Pq7tGtSA/p16F/UvRvT5pzfmpKsNGN6aQp5kJOGsfUBK3bPD4cA4eUcygyDyVDA GxYnmRrEgJfJVns4Rwbv/p3j8IedArNgFto9mqhOmbksu+5hUyQL5pSA8750dBSVlulQ o9+UOcIG9+h46w66HUdR28rde3mnPvZjC18Owqu+3Ac9+IZjbH56mpb0SeAeWe50Gvra XH0x34HezrWv/5cdiFKG7aui+mcDg0bKKEzapZjUTrbgYkEEUaJsWiIbX2lTb0Rpgn98 RncbTLvNYKweCIrtEwITprRFnZaXB12bU/qoJboXvFmOK+YeARPRNlkVr9vMFocrte/h o5fw== 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=KGBSJepcknEMLj2k6SdMfRjwwubO1aNnYzxXIxEr/uc=; b=f/9Ejrz+4NamyNBdk9huYggAQV1YJfDZXv70g39VTw/4tL/qdFSOqH4W/urI+qDG++ uECPVOirO/HsYP6ZEMijiWmPblJWj5OZerxccmlRr/NkYdp6opjxiDvcY6w1B1e2oFo6 FePEscntgr05ICNPjKMehkPcYg/yge6L7iCOgmYt3LCAEFY5Fu6dPHLHL9yjNQO7ase0 hQphCE4fBzohpXARDwo/wDTPHy3Ud+0u+sSOfapBCNoiEEaD9xLRA4HYGg7ZDhgBNm7x dXMilYDlSIjDuV63gOb9/YiE3Y3S868dS8P13d0lRtrZHKdNg5TgNXNrh7j3k+HAo5sF HSpw== X-Gm-Message-State: ALoCoQk7ZX2V41POjZvDKQyfOw5++GakbzvDlJ5Pw/+Fu+oLkYbri1fMOjDUuYViD6mr0GVuG6Bj X-Received: by 10.50.50.178 with SMTP id d18mr1881287igo.2.1402047840896; Fri, 06 Jun 2014 02:44:00 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.25.171 with SMTP id 40ls608776qgt.85.gmail; Fri, 06 Jun 2014 02:44:00 -0700 (PDT) X-Received: by 10.140.27.244 with SMTP id 107mr21237qgx.18.1402047840329; Fri, 06 Jun 2014 02:44:00 -0700 (PDT) In-Reply-To: <5380804B.80607@wanadoo.fr> 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:11106 Archived-At: ------=_Part_178_31535809.1402047839664 Content-Type: text/plain; charset=UTF-8 The original class was defined just as you propose. We moved to the current expected form to be able to write > > auto e = expected::make(1) // result is > expected > > Others have already do the same remark, and we would not have any problem > rolling back to the original design. We will need a different type > constructor expected_tc (a better name of course) > > auto e = expected_tc::make(1) // result is > expected With the original class defintion expected you can still achive very simliar inteface, by declaring: template expected make_expected(T); //This should use perfect forwarding and decay for argument, but it is cleaner that way Then you will be able to write: auto a = make_expected(1); // result is excepted auto b = make_expected(1);// result is expected -- --- 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_178_31535809.1402047839664 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
The original class was defined just as you propose. We mov= ed to the current expected<E,T> form to be able to write

auto e  =3D expected<error_condition>::make(1) // resul= t is expected<error_condition, int>

Others have already do the same remark, and we would not have any problem rolling back to the original design. We will need a different type constructor expected_tc (a better name of course)

auto e  =3D expected_tc<error_condition>::make(1) // re= sult is expected<error_condition, int
With the o= riginal class defintion expected<T,E> you can still achive very simli= ar inteface, by declaring:

template<typename E =3D exception_ptr,= T>
expected<T, E> make_expected(T); //This should use perfect = forwarding and decay for argument, but it is cleaner that way

Then y= ou will be able to write:
auto a =3D make_expected(1);     &nb= sp;                   // resul= t is excepted<int>
auto b =3D make_expected<error_condition>= (1);// result is expected<int, error_condition>

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