220 16984 <04b687bc-2cf5-402f-bb27-0365f77169b5@isocpp.org> article Path: news.gmane.org!not-for-mail From: inkwizytoryankes@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Token based access to private members in reflection Date: Fri, 13 Mar 2015 14:25:11 -0700 (PDT) Lines: 274 Approved: news@gmane.org Message-ID: <04b687bc-2cf5-402f-bb27-0365f77169b5@isocpp.org> References: <104b02bf-a3bc-495a-870e-9af9e1ec1fdf@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_837_985633932.1426281911699" X-Trace: ger.gmane.org 1426281915 17389 80.91.229.3 (13 Mar 2015 21:25:15 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 13 Mar 2015 21:25:15 +0000 (UTC) Cc: inkwizytoryankes@gmail.com To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDDLTAGNTIBBBOFLRWUAKGQEAH5M7IQ@isocpp.org Fri Mar 13 22:25:15 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qc0-f199.google.com ([209.85.216.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YWX50-00039G-6l for gclcip-std-proposals@m.gmane.org; Fri, 13 Mar 2015 22:25:14 +0100 Original-Received: by qcwr17 with SMTP id r17sf90823571qcw.0 for ; Fri, 13 Mar 2015 14:25:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:content-type:x-original-sender:reply-to:precedence :mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=mErgeXrUTn4kCwBzwr8nLYC1TITIdbbgbYNjBd6brlY=; b=PiF6igq8+1i9q2djL3EkkXLnJX0dqpiQSmSa1oGDCa4ceKZf/6mLN9ykgNLI+ABJ7U Vv4Z8eboIuZzJWOZuSiVRTwT60cFwR5bMXy7wBnMuPL9K/M+YflCFhBiCOi5l7t4C4Fe 7tjBeLH9JXLG71S0lpBV1Ovzuw4sFdSkyV3t0WrdDX7qf+dwyVMN8gALtzQAHoueUqA1 ecMCHO1+Di/usVBKybyb43N1wijPemGfrz8syoHF1sVrVzwU7oWuckWRktnbsopsX9Pj JBDh+OYcd0CG3oPi5zJOKD1+u/cR0rlIDP6HtxO0SxbLiUerQ35kCZ9lNqobRZdoKk+6 oJ+g== 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:cc:message-id:in-reply-to :references:subject:mime-version:content-type:x-original-sender :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=mErgeXrUTn4kCwBzwr8nLYC1TITIdbbgbYNjBd6brlY=; b=b+sh15e826puiGfmG+tw08bn9do/6ZYoSyPt8bJG64BCZk4RCbQHlyIhPtrgn1xoUN ewqQHCxaaMvO7+jxvA57O44dGNBSZjcalqpwIWsxB+K1WUrQJIbXeeoCDOUp7RU2Kb7H ZzWGIavGyUG7FJFb1o9pN2ghcUqw8gd3+YBYCnzmg/87V5Caiiyka2uidMEuiCsv0T2W 4BrnSSU4qKbKOz5DrKqwWWEJwrTIJGuJNuPuhR8yCmIm/TzL4N37FBNFg4zmG4xvYLU9 9Lqps5dxBetXomt+jzXWMj3OBdbze+ONKxPAxhWuDQv8/Fo+cGG6NQLz4M50af7v0zVR yyfQ== X-Gm-Message-State: ALoCoQlUaaZWI/htxIl1WDzSfNtxLZH0rR2x6Og9iq2MdqGYOBEnBhTivRchmhtgeDkIUEojZz6Q X-Received: by 10.52.166.77 with SMTP id ze13mr50392633vdb.9.1426281913076; Fri, 13 Mar 2015 14:25:13 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.84.198 with SMTP id l64ls1798946qgd.96.gmail; Fri, 13 Mar 2015 14:25:12 -0700 (PDT) X-Received: by 10.140.93.132 with SMTP id d4mr113378qge.9.1426281912335; Fri, 13 Mar 2015 14:25:12 -0700 (PDT) In-Reply-To: <104b02bf-a3bc-495a-870e-9af9e1ec1fdf@isocpp.org> X-Original-Sender: inkwizytoryankes@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:16984 Archived-At: ------=_Part_837_985633932.1426281911699 Content-Type: multipart/alternative; boundary="----=_Part_838_2008125813.1426281911699" ------=_Part_838_2008125813.1426281911699 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Do you know why people was against this approach? On Friday, March 13, 2015 at 12:22:15 AM UTC+1, Cleiton Santoia wrote: > > > > > In this document http://random.m-ou.se/reflectionfeedbackurbana.html = you=20 > will find : > > > Opt-in to unsafe reflection from the class under reflection: > SFFNASA543102 > > > > Em quinta-feira, 12 de mar=C3=A7o de 2015 19:46:29 UTC-3, inkwizyt...@gma= il.com=20 > escreveu: >> >> I have idea of system that could be used of handling private data in=20 >> reflection. >> >> First one, we add new template >> template >> class private_access_token >> { >> using type =3D /* undefined */; >> friend T; >> }; >> >> >> And we add to `class_member::pointer` (like from n4113) new default=20 >> parameter: >> template >> struct pointer >> { >> private: //this line depend if I'th member is private >> constexpr static SomeType T::* value =3D /* something */; >> friend T; >> }; >> >> template >> struct pointer::type > >> { >> public: //always public with token >> constexpr static SomeType T::* value =3D /* something */; >> friend T; >> }; >> >> >> >> >> Thanks to that, class implementation can have control over private acces= s=20 >> and allow sharing it to third party libraries without exposing private= =20 >> fields to the wild. >> Some class designer could even allow every one using it by exposing type= =20 >> form token: >> class A >> { >> int a; >> public: >> using PrivateToken =3D private_access_token::type; >> }; >> >> class B >> { >> int a; >> int b; >> public: >> std::string to_string() { return third_party_func< >> private_access_token::type>(this); } >> }; >> >> >> >> Do you think that could be good solution for that? >> >> >> --=20 ---=20 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 e= mail 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-proposa= ls/. ------=_Part_838_2008125813.1426281911699 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Do you know why people was against this approach?

O= n Friday, March 13, 2015 at 12:22:15 AM UTC+1, Cleiton Santoia wrote:




Opt-= in to unsafe reflection from the class under reflection:

<= thead><= th style=3D"text-align:center;font-weight:bold;border:1px solid rgb(211,211= ,211);padding:4pt;background:rgb(238,238,238)" align=3D"left">N
SF= FASA
543102



Em quinta-feira, 12 de mar=C3=A7o de 2015 19:46:29 UTC= -3, inkwizyt...@gmail.com escreveu:
I have idea of system that could be used of handli= ng private data in reflection.

First one, we add new template
template<<= span style=3D"color:#008">typename T>
class priva= te_access_token
{
    using type =3D /* undefi= ned */;=
    friend T;
};


And we add to `class_memb= er::pointer` (like from n4113) new default parameter:
template<typename T, size_t I, token =3D void>
struct pointer
{=
private: <= span style=3D"color:#800">//this line depend if I'th member is private
    constexpr static SomeType T::* value =3D /* something */;
    f= riend T= ;
};=

template<typename T, size_t I>
struct pointer<T, I, typename private_access_token<= /span><T>::type= >{
= public:= //alwa= ys public with token
    constexpr = static = SomeType T::* = value =3D /* something */;
    friend T;
};




Thanks to that, class implementation can have = control over private access and allow sharing it to third party libraries w= ithout exposing private fields to the wild.
Some class designer could ev= en allow every one using it by exposing type form token:
class A
{
    int a;
public:
    us= ing Pri= vateToken =3D private_access_token<A>::type;
};

class B
<= span style=3D"color:#660">{
  &nb= sp; int= a;
=     int b;
public:
    std::string to_string() { return third_party_func<private_access_token<B>::type>(this<= span style=3D"color:#660">); }
};



Do you think that could be good solution for that?

--

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To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
To post to this group, send email to std-proposals@isocpp.org.
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