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[80.12.242.126]) by mx.google.com with ESMTPS id bk7si49051512wjb.34.2015.12.28.16.48.56 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 28 Dec 2015 16:48:56 -0800 (PST) Received-SPF: neutral (google.com: 80.12.242.126 is neither permitted nor denied by best guess record for domain of vicente.botet@wanadoo.fr) client-ip=80.12.242.126; Original-Received: from new-host.home ([2.11.57.184]) by mwinf5d07 with ME id zCov1r00H3yV0bE03Cov6p; Tue, 29 Dec 2015 01:48:56 +0100 X-ME-Helo: new-host.home X-ME-Auth: dmljZW50ZS5ib3RldEB3YW5hZG9vLmZy X-ME-Date: Tue, 29 Dec 2015 01:48:56 +0100 X-ME-IP: 2.11.57.184 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 In-Reply-To: <56770133.7070701@wanadoo.fr> X-Original-Sender: vicente.botet@wanadoo.fr X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 80.12.242.126 is neither permitted nor denied by best guess record for domain of vicente.botet@wanadoo.fr) smtp.mailfrom=vicente.botet@wanadoo.fr 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: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:23243 Archived-At: This is a multi-part message in MIME format. --------------070409020409080900010803 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Adding std-proposals Vicente Le 20/12/2015 20:27, Vicente J. Botet Escriba a =C3=A9crit : > Hi, > > Based on the reflection traitsfrom n4428I would like to have the=20 > following tuple like traits specializations for a POD struct C. > > template <> > struct tuple_size :=20 > size_t_constant::class_members::size> {}; > > template > struct tuple_element :=20 > id().*declval::base_members= ::get::pointer>())>=20 > {}; > > template > requires N < std::class_traits::class_members::size > constexpr tuple_element_t& get(C & that) noexcept > { > std::class_traits::base_members::get::pointer pm; > return that.*pm; > } > > template > requires N < std::class_traits::class_members::size > constexpr const tuple_element_t& get(const C & that) noexcept > { > std::class_traits::base_members::get::pointer pm; > return that.*pm; > } > > template > requires N < std::class_traits::class_members::size > constexpr tuple_element_t&& get(C && that) noexcept > { > std::class_traits::base_members::get::pointer pm; > return std::forward&&>(that.*pm); > } > > /// the same for get with a type > > However, I would like to do it for some more classes C1, C2, ... > > I have added a trait tuple_like that states if I want the generation > > template > struct tuple_like: false_type {}; > > but I don't see how to make the specialization conditional to this=20 > traits without adding an Enabler parameter > > template > struct tuple_size; > template > struct tuple_element; > > Is there a way without changing the std::tuple_size and=20 > std::tuple_element template parameters? > What would be the the correct way to do that? > > Vicente=20 --=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 https://groups.google.com/a/isocpp.org/group/std-propos= als/. --------------070409020409080900010803 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Adding std-proposals
Vicente

Le 20/12/2015 20:27, Vicente J. Botet Escriba a =C3=A9crit=C2=A0:
Hi,

Based on the reflection traits from n4428 I would like to have the following <= font size=3D"+1">tuple like traits specializations for a POD struct C.

template <>
struct tuple_size<C> : size_t_constant<std::class_traits<C>::class_members::size> {};

template <size_t N>
struct tuple_element<N, C> : id<decltype(std::declval<C>().*declval<std= ::class_traits<C>::base_members::get<N>::pointer>())> {};

template <size_t N>
requires N < std::class_t= raits<C>::class_members::size
=C2=A0constexpr tuple_element_t<N,C>& get(C & that) noexcept
{
=C2=A0=C2=A0=C2=A0 std::class_traits<C>::base_member= s::get<N>::pointer pm; =C2=A0
=C2=A0=C2=A0=C2=A0 return that= .*pm;
}

template <size_t N>
requires N < = std::class_traits<C>::class= _members::size
constexpr const tuple_element_t<N,C>& get(const C & that) noexcept
{
=C2=A0=C2=A0=C2=A0 std::class_traits&= lt;C>::base_me= mbers::get<N>::pointer pm; =C2=A0
=C2=A0=C2=A0=C2=A0 return = that.*pm;
}

template <size_t N>
requires N < std::class_t= raits<C>::class_members::size
constexpr tuple_element_t<N,C>&& get(C && that) noexcept
{
=C2=A0=C2=A0=C2=A0 std::class_traits<C>::base_member= s::get<N>::pointer pm; =C2=A0
=C2=A0=C2=A0=C2=A0 return std:= :forward<tuple_element_t&= lt;N,C>&&>(that.*pm);
}

/// the same for get with a type

However, I would like to do it for some more classes C1, C2, ...

I have added a trait tuple_like that states if I want the generation

template <class T>
struct tuple_like: false_type {};

but I don't see how to make the specialization conditional to this traits without adding an Enabler parameter

=C2=A0=C2=A0=C2=A0 temp= late <class T, class Enabler=3Dvoid>
=C2=A0= =C2=A0=C2=A0 struct tuple_size;
=C2=A0=C2=A0=C2=A0 template <= ;size_t N, class T, class Enabler=3Dvo= id>
=C2=A0=C2=A0=C2=A0 struct tuple_element;

Is there a way without changing the std::tuple_size and std::tuple_element template parameters?
What would be the the correct way to do that?<= /c>
Vicente

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