220 25053 <741522c6-22f7-441d-81ab-e1ca44e085dc@isocpp.org> article Path: news.gmane.org!not-for-mail From: Cleiton Santoia Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: "Components" template with implicitly defined partial specializations for all classes Date: Tue, 8 Mar 2016 08:31:07 -0800 (PST) Lines: 153 Approved: news@gmane.org Message-ID: <741522c6-22f7-441d-81ab-e1ca44e085dc@isocpp.org> References: <56D9E17F.2070202@wanadoo.fr> <2b0bcca0-0939-49f7-939b-4d688f8dfe34@isocpp.org> <324dbff9-84da-46f2-b2f3-3d9fe0cc2082@isocpp.org> <56DA88DF.90000@wanadoo.fr> <7e46c46d-2e18-4cec-92c1-4f4d7fbc786b@isocpp.org> <39bbeb02-62b8-497b-8d65-5780a6baca97@isocpp.org> <05ac78e7-3d30-4a99-ad0f-a3d29497e2ff@isocpp.org> <2c7cb187-ad83-4ceb-af8b-1e61d4fb4d0d@isocpp.org> <56DD28C8.7020708@wanadoo.fr> <840b1f9a-be05-4454-b20d-99e2ccb3c1f1@isocpp.org> <390f2de7-6ab3-47cc-b76c-a7454dec5fc5@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; 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Tue, 08 Mar 2016 08:31:08 -0800 (PST) X-Received: by 10.50.25.167 with SMTP id d7mr221841igg.7.1457454668106; Tue, 08 Mar 2016 08:31:08 -0800 (PST) In-Reply-To: <390f2de7-6ab3-47cc-b76c-a7454dec5fc5@isocpp.org> X-Original-Sender: cleitonsantoia@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: Original-Sender: std-proposals@isocpp.org List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:25053 Archived-At: ------=_Part_180_1155276388.1457454667175 Content-Type: multipart/alternative; boundary="----=_Part_181_1148837050.1457454667175" ------=_Part_181_1148837050.1457454667175 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable > > In the example you gave for a generic =3D=3D operator, the equals_helper= =20 > template function could be wrapped in a helper class. A class with=20 > non-public data components could friend the helper class if the generic= =20 > operator was correct for it. In a sense, the default constructors,=20 > destructor and assignment operator are all reinventions of the "foreach= =20 > component reflection" wheel. We can continue the multiple reinventions f= or=20 > the comparison operators (also a violation of strictest respect for acces= s=20 > control). Or (assuming that friending a helper class works in general)= =20 > classes with non-public data components can acknowledge library default= =20 > functions and operators with a single simple friend declaration. Lobbyis= ts=20 > for companies wanting to sell library include file upgrades will wine and= =20 > dine the Committee in support of this. > My intent is to make a two cents contribution and show how terse and easy= =20 can be (reflection + folding) to solve the problem of the subject of this= =20 topic, also give a alternative solution than you thought, without need for= =20 mapping classes nor "Component/Class/Fields" structures. I=C2=B4m not tryin= g to=20 provide the whole solution for default comparison nor solve all issues in L= awrence=20 Crowl =E2=80=9CComparison is not simple, but it can be simpler"=20 but if you wish, you can sh= ow=20 us your idea then we can comment on it. =20 > Since you mention an is_base predicate, I assume that means you have some= =20 > sort of member pointer to a base class, but I see no explicit discussion = of=20 > that.=20 > Sorry, I did not get this, why you need a member pointer to a base class ?= =20 struct X{ }; struct Y : X { X* base; }; you mean this ??? --=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. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/741522c6-22f7-441d-81ab-e1ca44e085dc%40isocpp.or= g. ------=_Part_181_1148837050.1457454667175 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
In the e= xample you gave for a generic =3D=3D operator, the equals_helper template f= unction could be wrapped in a helper class. A class with non-public data co= mponents could friend the helper class if the generic operator was correct = for it.=C2=A0 In a sense, the default constructors, destructor and assignme= nt operator are all reinventions of the "foreach component reflection&= quot; wheel.=C2=A0 We can continue the multiple reinventions for the compar= ison operators (also a violation of strictest respect for access control).= =C2=A0 Or (assuming that friending a helper class works in general) classes= with non-public data components can acknowledge library default functions = and operators with a single simple friend declaration.=C2=A0 Lobbyists for = companies wanting to sell library include file upgrades will wine and dine = the Committee in support of this.

My intent is to make a two cents contribution and show how terse and eas= y can be (reflection + folding) to solve the problem of the subject of this= topic, also give a alternative solution than you thought, without need for= mapping classes nor "Component/Class/Fields" structures. I=C2=B4= m not trying to provide the whole solution for default comparison nor solve= all issues in La= wrence Crowl =E2=80=9CComparison is not simple, but it can be simpler"= =C2=A0but if you wish, you can show us your idea then we can comment on= it.

=C2=A0
Since you mention an is_base predicate, I= assume that means you have some sort of member pointer to a base class, bu= t I see no explicit discussion of that.
<= br>
Sorry, I did not get this, why you need a member pointer to a= base class ?=C2=A0

str= uct X{
};

struct Y : X {
=C2=A0 =C2=A0X*= base;
};
<= br>
you mean this ???

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