220 24925 <3c8bb230-c83b-4c18-95b6-1cc32caae76d@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: Fri, 4 Mar 2016 10:02:43 -0800 (PST) Lines: 117 Approved: news@gmane.org Message-ID: <3c8bb230-c83b-4c18-95b6-1cc32caae76d@isocpp.org> References: <92a6bfcf-0100-40b2-8946-a9c634783ec9@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1177_328122249.1457114563966" X-Trace: ger.gmane.org 1457114575 17634 80.91.229.3 (4 Mar 2016 18:02:55 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 4 Mar 2016 18:02:55 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCBMVWMTUUNBBRU3463AKGQEKF6PBRY@isocpp.org Fri Mar 04 19:02:50 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pa0-f72.google.com ([209.85.220.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1abu3s-0006Rd-B1 for gclcip-std-proposals@m.gmane.org; Fri, 04 Mar 2016 19:02:48 +0100 Original-Received: by mail-pa0-f72.google.com with SMTP id fl4sf73904553pad.2 for ; Fri, 04 Mar 2016 10:02:48 -0800 (PST) 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:sender :list-subscribe:list-unsubscribe; bh=ssxicBYeCcsOrbooHDmwl17NtxDx4b8GYCCZiqq45Cc=; b=LM8/fkxrKnGufrPadRQkmAdCvLHqmkm9r2SVaUXK+8LzbxOtchWjaIsFeUhdHsgRcw nqjaChI/SMe0FCe3gefhmBbLSUCN9ntcqPFL2Zv88gQRr//HC/PNgOp0okXoNz6aseMQ HjV7du9YcypYNfzGwuKPPoV9JlmcecmruK+reoSd3lR6QTzoVBsHyROJXPBikz9WVk7e UoC+I0AXCsTkCkMqRNgYJIrNKWxWfCFPQwCS2xfPzziEDaX4bA6Y1//vGK2KGOo4dP/R EX7red6SEfTy4fL+wQpFYOt3TjfL96YWg92O03kEemU4Lqp3e7MBE6D/te/aY68txKau Cz8Q== 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 :x-spam-checked-in-group:list-post:list-help:list-archive:sender :list-subscribe:list-unsubscribe; bh=ssxicBYeCcsOrbooHDmwl17NtxDx4b8GYCCZiqq45Cc=; b=KVOqqt+xRAYFqakfWC+7MWGmOQcJxC9cPXaC1vux9UvoeZF/79QZzGNX5/Cx08b6HT iH+6dxaGh9aGTZMNHmwTWWCbsp1iVGCpmywhgRDYAP+Mqt9biLaz74/DOhtOULXy/pu0 tJTnPb40hHrdu/KpZHBbttyk7ykl9XYpAqlH1WfDd26LCVsAni9SQlYsb1PdXZUYVrEx SC+ItO/cdYpxvd8TYgLVjG8IRdX9Myo1h8qk9J/uQk7tswqG9hBePUPxjFNL/UIplF3z tBW5/LUi5iJ18u+4a0O6P0ymZpwryxTHe6VOTC5dlkfYxCK2M5GrzRTzPj3nWVV9fupE rNxA== 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:x-spam-checked-in-group:list-post:list-help :list-archive:sender:list-subscribe:list-unsubscribe; bh=ssxicBYeCcsOrbooHDmwl17NtxDx4b8GYCCZiqq45Cc=; b=WewchGh4nfZ9kvc864Og++kkxedH7y3Wm7lB3KiuZhu4yPTOEEkfaijFr9Yx5vRFIm QLEBsUlfBSruE+t9rnK4Us3OaESG+P6cPhOKQXeZgk1jzlK+ls4z8nyGfIKgSorqrfOi IoZi1txqCTDECtw/bICh5orKFPxM0AqROxDPm9JBp8fxrcZUPgJssbnPwjbH9PCcoGZV Qfuktq2deO7yTpE9aBZcwqXoei80lj5Q1j7NZAvjEiJ5mcBp5NzBym74PAHpef2mBSGX s1WmXbmR0bVdHed9M4AjYlP+udL3fYZWcglRECIC6eyyePfa6Dg0BJN3c+McAciZgDAB Vn7Q== X-Gm-Message-State: AD7BkJKRUHRsNs17Xaezs2Zcho+TFQpAJq12L82lykRt4W4MrwSZpHYCLj92/k+/fjd0ZA== X-Received: by 10.66.171.167 with SMTP id av7mr6597589pac.17.1457114567215; Fri, 04 Mar 2016 10:02:47 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.67.69 with SMTP id l5ls367100igt.30.canary; Fri, 04 Mar 2016 10:02:45 -0800 (PST) X-Received: by 10.50.43.234 with SMTP id z10mr9782igl.4.1457114565912; Fri, 04 Mar 2016 10:02:45 -0800 (PST) In-Reply-To: <92a6bfcf-0100-40b2-8946-a9c634783ec9@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:24925 Archived-At: ------=_Part_1177_328122249.1457114563966 Content-Type: multipart/alternative; boundary="----=_Part_1178_1609385642.1457114563967" ------=_Part_1178_1609385642.1457114563967 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Reflection ? p0255r0=20 X...> solves your case.... Em sexta-feira, 4 de mar=C3=A7o de 2016 02:01:15 UTC-3, Walt Karas escreveu= : > > Another possible approach generic mapping of operations to components=20 > would be to accept the idiom ++C , C a class name, as a template=20 > parameter. The compiler would implicitly expand ++C to multiple=20 > parameters, namely C itself, followed by a pair of parameters for each=20 > component of C. Each pair would consist of the type T of the component,= =20 > followed by the member pointer of type T C::* to the component. (The=20 > reason for using ++ is to suggest iteration of over the components.) For= =20 > example, for this class: > > struct A { int i, j; double x; }; > > the template instantiation: > > X<++A> > > would be equivalent to: > > X > > This hopefully would allow variadic templates to create reasonable defaul= t=20 > comparison, input and display, persistence, endiance swap, hashing, etc.= =20 > operations for many classes. A difficult issue would be wether the conte= xt=20 > where X<++A> is instantiated would be required to have access to all the= =20 > implicitly reverenced component types and components themselves. > > Perhaps the compiler could also except the idiomatic template parameter= =20 > --C, which would lay out the components in reverse order (of destruction)= =20 > rather than forward order (of construction). > --=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/3c8bb230-c83b-4c18-95b6-1cc32caae76d%40isocpp.or= g. ------=_Part_1178_1609385642.1457114563967 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

=C2=A0 =C2=A0Reflection ?=C2=A0p0255r0=

X<typedef<A>...> solves your case....
=




Em sexta-feira, 4 de mar=C3=A7o = de 2016 02:01:15 UTC-3, Walt Karas escreveu:
Another possible approach generic mapping o= f operations to components would be to accept the idiom ++C , C a class nam= e, as a template parameter.=C2=A0 The compiler would implicitly expand ++C = to multiple parameters, namely C itself, followed by a pair of parameters f= or each component of C.=C2=A0 Each pair would consist of=C2=A0 the type T o= f the component, followed by the member pointer of type T C::* to the compo= nent.=C2=A0 (The reason for using ++ is to suggest iteration of over the co= mponents.)=C2=A0 For example, for this class:

struct A { int i, j; d= ouble x; };

the template instantiation:

X<++A>

w= ould be equivalent to:

X<A, int, &C::i, int, &C::j, doubl= e, &C::x>

This hopefully would allow variadic templates to cr= eate reasonable default comparison, input and display, persistence, endianc= e swap, hashing, etc. operations for many classes.=C2=A0 A difficult issue = would be wether the context where X<++A> is instantiated would be req= uired to have access to all the implicitly reverenced component types and c= omponents themselves.

Perhaps the compiler could also except the idi= omatic template parameter --C, which would lay out the components in revers= e order (of destruction) rather than forward order (of construction).

--
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