220 34965 <7f22751b-91d1-4de4-81d2-421046ceb963@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Mingxin Wang Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Idea about "std::pmr::memory_resource" Date: Mon, 16 Oct 2017 08:11:02 -0700 (PDT) Lines: 601 Approved: news@gmane.org Message-ID: <7f22751b-91d1-4de4-81d2-421046ceb963@isocpp.org> References: <0a8293b4-3246-47a5-9881-bc1ca4b91772@isocpp.org> <07ddb1f6-d3af-43df-bf96-8975c1ab4313@isocpp.org> <2e191a96-1952-479b-b78b-22e31f8e03de@isocpp.org> <0e37b5ae-64f6-4a8a-86bd-f44b119ed40a@isocpp.org> <15f8c5ba-3a6a-4441-9620-92e157c66094@isocpp.org> <26fe4cb4-98ca-41cc-ac96-5c51851799d1@isocpp.org> <784ffce8-ace7-449d-a13d-a99d7336117a@isocpp.org> <6d0ad98b-87d5-43dd-ac54-2b7d3e03e31b@isocpp.org> <4af80cf7-244c-4137-9133-1a36a209e4ca@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_17683_777117230.1508166662511" X-Trace: blaine.gmane.org 1508166681 5687 195.159.176.226 (16 Oct 2017 15:11:21 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 16 Oct 2017 15:11:21 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDNMBNHJWIGBBB4YSPHQKGQE225HMOI@isocpp.org Mon Oct 16 17:11:16 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f72.google.com ([209.85.213.72]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e472j-0007gA-0p for gclcip-std-proposals@m.gmane.org; Mon, 16 Oct 2017 17:11:01 +0200 Original-Received: by mail-vk0-f72.google.com with SMTP id q80sf6134767vka.21 for ; Mon, 16 Oct 2017 08:11:08 -0700 (PDT) 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 :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=T4aeQqGNCwqBVHFLVmib2zJDeF4u/yydph3R9T2O90Q=; b=w1dstU1uRxKCHpBjtO+fequad7JZTTRVq56dAQoWhTzqNwvce/irneLrFl27OXmv+W fu2APH/byLcbZyj7krvWJ+wQ7YqKQvZRp6ZeloTv73tUNEzshU5DSYpkf/o6U36Eo2kq YKeH2saDwrxBANuAG1q+XMIht81X3Z62ZgnBt6ORFxpfrP5TiI/hhy/egzPhsK5oQsPp RzEEn7V6rnFhzJBX1uVB3Q1omBgVkXYWXbbutX2i0G92u2HwdgHVCEzyTkcm5q2j/MZu PHITJDzUSaAj9BmvAT/Mf0kwFk65jK9sI++LYm8vAIO3bIF6Qn8FAcPO0FALjUlqI1rG ESqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; 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:list-subscribe:list-unsubscribe; bh=T4aeQqGNCwqBVHFLVmib2zJDeF4u/yydph3R9T2O90Q=; b=YwXMTY0z/eCzC+LOl7h/ATSio8NoXUvVwKKqvysMRQIZJLany6QVfZaviulp/IJzg+ ML1FjKI3L+Uvchv8LO18Niw6aUgLAyHmRAFoDka/9Gtqtlwi2o//M0VFhhuHMaabDwVo uHX9PyCUnN02wChI/hgrM61844vG1WGU37nUReYHk+nCtKEoUpjXqcaOH7lKK1rIiweu aByY8cKJ6yLTB0eZcDnSW0EXulA2z0BY3P47/DP3ASsJrUmLOFMdGhi88/RjGJxbD/EX Q/wdLkz9sfuDciKds4LEE5p8GgSZaBm6ox6ruBoI6DvWsBWS+u7Z9b+lE0wX9uafs3xy yqCg== X-Gm-Message-State: AMCzsaXjbkW1vkkD4TJygLCeBpM3nzXhw5dUNw5Q2qQ3cdBJgsyHJKXg bCA/MgwTYYDWsktz+ELQiIV8FA== X-Google-Smtp-Source: AOwi7QDc/bUIX9glZuMZpWy5IebQvEVIxRcXh4RD2L2YUJ/20iSLFkuAHInbirHmrkWyy3vZZkME8w== X-Received: by 10.176.1.227 with SMTP id 90mr5284379ual.87.1508166668180; Mon, 16 Oct 2017 08:11:08 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.31.21.72 with SMTP id 69ls3368836vkv.17.gmail; Mon, 16 Oct 2017 08:11:03 -0700 (PDT) X-Received: by 10.31.50.18 with SMTP id y18mr154190vky.6.1508166663198; Mon, 16 Oct 2017 08:11:03 -0700 (PDT) In-Reply-To: <4af80cf7-244c-4137-9133-1a36a209e4ca@isocpp.org> X-Original-Sender: wmx16835vv@163.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:34965 Archived-At: ------=_Part_17683_777117230.1508166662511 Content-Type: multipart/alternative; boundary="----=_Part_17684_234504532.1508166662513" ------=_Part_17684_234504532.1508166662513 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Monday, October 16, 2017 at 8:26:57 PM UTC+8, Aleksey Loginov wrote: > > =D0=BF=D0=BE=D0=BD=D0=B5=D0=B4=D0=B5=D0=BB=D1=8C=D0=BD=D0=B8=D0=BA, 16 = =D0=BE=D0=BA=D1=82=D1=8F=D0=B1=D1=80=D1=8F 2017 =D0=B3., 15:08:45 UTC+3 =D0= =BF=D0=BE=D0=BB=D1=8C=D0=B7=D0=BE=D0=B2=D0=B0=D1=82=D0=B5=D0=BB=D1=8C Mingx= in Wang=20 > =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB: >> >> On Monday, October 16, 2017 at 6:55:41 PM UTC+8, Aleksey Loginov wrote: >>> >>> Let's look at a more applied example: >>> >>> template=20 >>> struct static_resource : memory_resource { aligned_storage_t=20 >>> m_data; }; >>> >>> template >>> struct my_any; >>> >>> >>> my_any x1; >>> my_any> x2; >>> >>> x1 =3D 1; >>> x2 =3D x1; >>> >>> assert(x2 =3D=3D 1); >>> >>> >>> How can you do this without RTTI? >>> >> >> And I don't think `x2` should be copy-assignable from `x1`, if >> >> - `static_resource<32>` is not copy-constructible from=20 >> `default_memory_resource`, or >> - the two memory resources could not be reflexive (being reflexive=20 >> means, you could allocate some memory from one, and deallocate the me= mory=20 >> from another). >> >> >> > So x1 =3D 1 is valid, but x2 =3D x1 is not valid? Why? > x2 doesn't deallocates from default_memory_resource. It work only with=20 > static_resource. > =20 I am sorry, `x2 =3D x1` *should* be a valid expression. I misjudged the cod= e=20 and thought it were an assignment between memory resources. The class template `my_any` may declare any `my_any` types as friend have= =20 overloads of `operator=3D` for them: template friend class my_any; template my_any& operator=3D(const my_any<_MR>&); template my_any& operator=3D(my_any<_MR>&&); In order to prove that the class template `my_any` is implementable, I have= =20 roughly implemented one that supports various of constructors, `operator=3D= `,=20 `type()` and `get()`. You may use `type()` and `get()` to implement=20 those non-member function templates like `any_cast`. struct manager_t { public: template constexpr explicit manager_t(std::in_place_type_t) : type(typeid(T)), do_copy(do_copy_impl), do_move(do_move_impl), do_destroy(do_destroy_impl), size(sizeof(T)) {} constexpr explicit manager_t(std::nullptr_t) : type(typeid(void)), do_copy(do_copy_null), do_move(do_move_null), do_destroy(do_destroy_null), size(0) {} constexpr bool soo_activated() const { return size <=3D sizeof(void*); } template void copy(void** from, void** to, MR& mr) const { if (soo_activated()) { do_copy(from, to); } else { *to =3D mr.allocate(size, ALIGNMENT); do_copy(*from, *to); } } void* get(void** data) const { return soo_activated() ? data : *data; } template void move(void** from, void** to, MR& mr) const { if (soo_activated()) { do_move(from, to); } else { *to =3D mr.allocate(size, ALIGNMENT); do_move(*from, *to); } } template void destroy(void** data, MR& mr) const { if (soo_activated()) { do_destroy(data); } else { do_destroy(*data); mr.deallocate(*data, size, ALIGNMENT); } } const std::type_info& type; static inline constexpr std::size_t ALIGNMENT =3D alignof(std::max_align_= t); private: void(*do_copy)(void*, void*); void(*do_move)(void*, void*); void(*do_destroy)(void*); std::size_t size; template static inline void do_copy_impl(void* from, void* to) { new (reinterpret_cast(to)) T(*reinterpret_cast(from)); } template static inline void do_move_impl(void* from, void* to) { new (reinterpret_cast(to))=20 T(std::move(*reinterpret_cast(from))); } template static inline void do_destroy_impl(void* data) { reinterpret_cast(data)->~T(); } static inline void do_copy_null(void*, void*) {} static inline void do_move_null(void*, void*) {} static inline void do_destroy_null(void*) {} }; template inline constexpr manager_t MANAGER{std::in_place_type}; inline constexpr manager_t NULL_MANAGER{nullptr}; template struct memory_resource_user { MR mr_; }; template class my_any; template struct is_my_any : std::false_type {}; template struct is_my_any> : std::true_type {}; template inline constexpr bool is_my_any_v =3D is_my_any::value; template class my_any : public memory_resource_user { template friend class my_any; public: template my_any(T&& data) requires !is_my_any_v> { init(std::in_place_type>, std::forward(data)); } template explicit my_any(std::in_place_type_t, Args&&... args) { init(std::in_place_type, std::forward(args)...); } template explicit my_any(std::in_place_type_t, std::initializer_list il,=20 Args&&... args) { init(std::in_place_type, il, std::forward(args)...); } constexpr my_any() noexcept { init(); } my_any(const my_any& rhs) { copy_init(rhs); } my_any(my_any&& rhs) noexcept { move_init(rhs); } template my_any(const my_any<_MR>& rhs) { copy_init(rhs); } template my_any(my_any<_MR>&& rhs) noexcept { move_init(rhs); } ~my_any() { deinit(); } template my_any& operator=3D(T&& data) requires !is_my_any_v> { deinit(); init(std::in_place_type>, std::forward(data)); return *this; } template my_any& operator=3D(const my_any<_MR>& rhs) { deinit(); copy_init(rhs); return *this; } template my_any& operator=3D(my_any<_MR>&& rhs) { deinit(); move_init(rhs); return *this; } void* get() const noexcept { return manager_->get(&data_); } bool has_value() const noexcept { return manager_ !=3D &NULL_MANAGER; } const std::type_info& type() const noexcept { return manager_->type; } private: void init() { manager_ =3D &NULL_MANAGER; } template void init(std::in_place_type_t, Args&&... args) requires=20 (MANAGER.soo_activated()) { manager_ =3D &MANAGER; new (reinterpret_cast(&data_)) T(std::forward(args)...); } template void init(std::in_place_type_t, Args&&... args) requires=20 (!MANAGER.soo_activated()) { manager_ =3D &MANAGER; data_ =3D this->mr_.allocate(sizeof(T), manager_t::ALIGNMENT); new (reinterpret_cast(data_)) T(std::forward(args)...); } template void copy_init(const my_any<_MR>& rhs) { manager_ =3D rhs.manager_; manager_->copy(&rhs.data_, &data_, this->mr_); } template void move_init(my_any<_MR>& rhs) { manager_ =3D rhs.manager_; manager_->move(&rhs.data_, &data_, this->mr_); } void deinit() { manager_->destroy(&data_, this->mr_); } const manager_t* manager_; mutable void* data_; }; Mingxin Wang --=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/7f22751b-91d1-4de4-81d2-421046ceb963%40isocpp.or= g. ------=_Part_17684_234504532.1508166662513 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Monday, October 16, 2017 at 8:26:57 PM UTC+8, Aleksey L= oginov wrote:
= =D0=BF=D0=BE=D0=BD=D0=B5=D0=B4=D0=B5=D0=BB=D1=8C=D0=BD=D0=B8=D0=BA, 16 =D0= =BE=D0=BA=D1=82=D1=8F=D0=B1=D1=80=D1=8F 2017 =D0=B3., 15:08:45 UTC+3 =D0=BF= =D0=BE=D0=BB=D1=8C=D0=B7=D0=BE=D0=B2=D0=B0=D1=82=D0=B5=D0=BB=D1=8C Mingxin = Wang =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB:
On Monday, October 16, 2017 at 6:55:41 PM UTC= +8, Aleksey Loginov wrote:
Let's look at a more applied example:

template<= ;size_t Size>
struct static_resource : memory_resource { aligned_storage_t<Size>= m_data; };

template<typename MR>
struct=C2=A0my_any;


my_any<default_<= /span>memory_resource> x1;
my_any<static_resource<32>> x2;
=
x1 =3D 1;
x2 = =3D x1;

assert(x2 =3D=3D 1);


How can yo= u=C2=A0do this without RTTI?

An= d I don't think `x2` should be copy-assignable from `x1`, if
=
  • `static_resource<32>` is not copy-constructible from `default= _memory_resource`, or
  • the two memory resources could not be reflexi= ve (being reflexive means, you could allocate some memory from one, and dea= llocate the memory from another).


So x1 =3D 1 is valid, but x2 =3D x1 is not vali= d? Why?
x2 doesn't deallocates from default_memory_resource. = It work only with static_resource.
=C2=A0
I am sorry, `x2 =3D x1` should be a valid expression. I misjud= ged the code and thought it were an assignment between memory resources.

The class template `my_any` may declare any `my_any`= types as friend have overloads of `operator=3D` for them:

t= emplate <class _MR>
friend class m= y_any;

template <class _MR>
my_any= & operator=3D(const my_any<_MR>&);

template <class _MR>=
my_any& operator=3D(my_any<_MR&g= t;&&);

In order to prove that the= class template `my_any` is implementable, I have roughly implemented one t= hat supports various of constructors, `operator=3D`, `type()` and `get()`. = You may use `type()` and `get()` to implement those=C2=A0non-member functio= n templates like `any_cast`.

struct manager_t {
=C2=A0public:
=C2=A0 te= mplate <class T>
=C2=A0 constexpr = explicit manager_t(std::in_place_type_t<T>)
=C2=A0 =C2=A0 =C2=A0 : type(typeid(T)),
=C2=A0 =C2=A0 =C2=A0 =C2=A0 do_copy(do_copy_impl<T>),
=
=C2=A0 =C2=A0 =C2=A0 =C2=A0 do_move(do_move_i= mpl<T>),
=C2=A0 =C2=A0 =C2=A0 =C2= =A0 do_destroy(do_destroy_impl<T>),
=C2=A0 =C2=A0 =C2=A0 =C2=A0 size(sizeof(T)) {}

=C2=A0 constexpr explicit = manager_t(std::nullptr_t)
=C2=A0 =C2=A0 = =C2=A0 : type(typeid(void)),
=C2=A0 =C2= =A0 =C2=A0 =C2=A0 do_copy(do_copy_null),
=C2=A0 =C2=A0 =C2=A0 =C2=A0 do_move(do_move_null),
=C2=A0 =C2=A0 =C2=A0 =C2=A0 do_destroy(do_destroy_null),
<= div class=3D"subprettyprint">=C2=A0 =C2=A0 =C2=A0 =C2=A0 size(0) {}

=C2=A0 = constexpr bool soo_activated() const {
= =C2=A0 =C2=A0 return size <=3D sizeof(void*);
=C2=A0 }

=C2=A0 template <class MR>
=C2=A0 void copy(void** from, void** to, MR& mr) const {
=C2=A0 =C2=A0 if (soo_activated()) {
=C2=A0 =C2=A0 =C2=A0 do_copy(from, to);
=C2=A0 =C2=A0 } else {
=C2=A0 =C2=A0 =C2=A0 *to =3D mr.allocate(size, ALIGNMENT);
=C2=A0 =C2=A0 =C2=A0 do_copy(*from, *to);<= /div>
=C2=A0 =C2=A0 }
=C2=A0 }

=C2=A0 void* get(void** data) const {
=C2=A0 =C2=A0 return soo_activated() ? data : *data;
=C2=A0 }

=C2=A0 template <class MR><= /div>
=C2=A0 void move(void** from, void** to,= MR& mr) const {
=C2=A0 =C2=A0 if (s= oo_activated()) {
=C2=A0 =C2=A0 =C2=A0 d= o_move(from, to);
=C2=A0 =C2=A0 } else {=
=C2=A0 =C2=A0 =C2=A0 *to =3D mr.allocat= e(size, ALIGNMENT);
=C2=A0 =C2=A0 =C2=A0= do_move(*from, *to);
=C2=A0 =C2=A0 }
=C2=A0 }

=C2=A0 template <class MR><= /div>
=C2=A0 void destroy(void** data, MR&= mr) const {
=C2=A0 =C2=A0 if (soo_activ= ated()) {
=C2=A0 =C2=A0 =C2=A0 do_destro= y(data);
=C2=A0 =C2=A0 } else {
=C2=A0 =C2=A0 =C2=A0 do_destroy(*data);
=C2=A0 =C2=A0 =C2=A0 mr.deallocate(*data, size, = ALIGNMENT);
=C2=A0 =C2=A0 }
=C2=A0 }

=C2=A0 const std::type_info& type;

=C2= =A0 static inline constexpr std::size_t ALIGNMENT =3D alignof(std::max_alig= n_t);

=C2=A0private:
=C2=A0 void(*do_cop= y)(void*, void*);
=C2=A0 void(*do_move)(= void*, void*);
=C2=A0 void(*do_destroy)(= void*);
=C2=A0 std::size_t size;

=C2=A0 = template <class T>
=C2=A0 static i= nline void do_copy_impl(void* from, void* to) {
=C2=A0 =C2=A0 new (reinterpret_cast<T*>(to)) T(*reinterpret_c= ast<const T*>(from));
=C2=A0 }

=C2= =A0 template <class T>
=C2=A0 stat= ic inline void do_move_impl(void* from, void* to) {
=C2=A0 =C2=A0 new (reinterpret_cast<T*>(to)) T(std::move(= *reinterpret_cast<T*>(from)));
=C2= =A0 }

=C2=A0 template <class T>
= =C2=A0 static inline void do_destroy_impl(void* data) {
=C2=A0 =C2=A0 reinterpret_cast<T*>(data)->~T();
=C2=A0 }

=C2=A0 static inline void do_copy= _null(void*, void*) {}
=C2=A0 static inl= ine void do_move_null(void*, void*) {}
= =C2=A0 static inline void do_destroy_null(void*) {}
};

template <class T>
= inline constexpr manager_t MANAGER{std::in_place_type<T>};

inline con= stexpr manager_t NULL_MANAGER{nullptr};
=
template <class MR>
struct memory_resource_user {
=C2=A0 MR mr_;
};
<= div class=3D"subprettyprint">
templa= te <class MR>
class my_any;
<= div class=3D"subprettyprint">
templa= te <class T>
struct is_my_any : st= d::false_type {};

template <class MR>
struct is_my_any<my_any<MR>> : std::true_type {};

templat= e <class T>
inline constexpr bool = is_my_any_v =3D is_my_any<T>::value;

template <class MR>
<= div class=3D"subprettyprint">class my_any : public memory_resource_user<= MR> {
=C2=A0 template <class>
=C2=A0 friend class my_any;

=C2=A0public:=
=C2=A0 template <class T>
=C2=A0 my_any(T&& data) requires !is_my= _any_v<std::decay_t<T>>
=C2= =A0 =C2=A0 =C2=A0 { init(std::in_place_type<std::decay_t<T>>, s= td::forward<T>(data)); }

=C2=A0 template <class T, class... Args&g= t;
=C2=A0 explicit my_any(std::in_place_= type_t<T>, Args&&... args)
=C2=A0 =C2=A0 =C2=A0 { init(std::in_place_type<T>, std::forward<A= rgs>(args)...); }

=C2=A0 template<class T, class U, class... Args>=
=C2=A0 explicit my_any(std::in_place_ty= pe_t<T>, std::initializer_list<U> il, Args&&... args)
=C2=A0 =C2=A0 =C2=A0 { init(std::in_place= _type<T>, il, std::forward<Args>(args)...); }

=C2=A0 constexp= r my_any() noexcept { init(); }

=C2=A0 my_any(const my_any& rhs) { copy= _init(rhs); }
=C2=A0 my_any(my_any&&= amp; rhs) noexcept { move_init(rhs); }
<= br>
=C2=A0 template <class _MR>
=C2=A0 my_any(const my_any<_MR>&= rhs) { copy_init(rhs); }

=C2=A0 template <class _MR>
=C2=A0 my_any(my_any<_MR>&& rhs) noexcept= { move_init(rhs); }

=C2=A0 ~my_any() { deinit(); }

=C2=A0 template <cla= ss T>
=C2=A0 my_any& operator=3D(= T&& data) requires !is_my_any_v<std::decay_t<T>> {
=C2=A0 =C2=A0 deinit();
=C2=A0 =C2=A0 init(std::in_place_type<std::decay_t<T&g= t;>, std::forward<T>(data));
= =C2=A0 =C2=A0 return *this;
=C2=A0 }

=C2= =A0 template <class _MR>
=C2=A0 my= _any& operator=3D(const my_any<_MR>& rhs) {
=C2=A0 =C2=A0 deinit();
=C2=A0 =C2=A0 copy_init(rhs);
=C2=A0= =C2=A0 return *this;
=C2=A0 }

=C2=A0 te= mplate <class _MR>
=C2=A0 my_any&a= mp; operator=3D(my_any<_MR>&& rhs) {
=C2=A0 =C2=A0 deinit();
=C2= =A0 =C2=A0 move_init(rhs);
=C2=A0 =C2=A0= return *this;
=C2=A0 }

=C2=A0 void* ge= t() const noexcept {
=C2=A0 =C2=A0 retur= n manager_->get(&data_);
=C2=A0 }=

=C2=A0 bool has_value() const noexcept {
=C2=A0 =C2=A0 return manager_ !=3D &NULL_MANAGER;
=C2=A0 }

=C2=A0 const std::type_info& type() const noex= cept {
=C2=A0 =C2=A0 return manager_->= ;type;
=C2=A0 }

=C2=A0private:
=C2=A0 void init() { manager_ =3D &NULL_MANAG= ER; }

=C2=A0 template <class T, class... Args>
=C2=A0 void init(std::in_place_type_t<T>, Args&&= .... args) requires (MANAGER<T>.soo_activated()) {
=C2=A0 =C2=A0 manager_ =3D &MANAGER<T>;
=C2=A0 =C2=A0 new (reinterpret_cast<T*>(&am= p;data_)) T(std::forward<Args>(args)...);
=C2=A0 }

=C2=A0 template <class T, class... Args>
=C2=A0 void init(std::in_place_type_t<T>, Arg= s&&... args) requires (!MANAGER<T>.soo_activated()) {
=C2=A0 =C2=A0 manager_ =3D &MANAGER<T>= ;;
=C2=A0 =C2=A0 data_ =3D this->mr_.= allocate(sizeof(T), manager_t::ALIGNMENT);
=C2=A0 =C2=A0 new (reinterpret_cast<T*>(data_)) T(std::forward<= Args>(args)...);
=C2=A0 }

=C2=A0 temp= late <class _MR>
=C2=A0 void copy_= init(const my_any<_MR>& rhs) {
=C2=A0 =C2=A0 manager_ =3D rhs.manager_;
=C2=A0 =C2=A0 manager_->copy(&rhs.data_, &data_, this->mr_)= ;
=C2=A0 }

=C2=A0 template <class _MR= >
=C2=A0 void move_init(my_any<_MR= >& rhs) {
=C2=A0 =C2=A0 manager_ = =3D rhs.manager_;
=C2=A0 =C2=A0 manager_= ->move(&rhs.data_, &data_, this->mr_);
=C2=A0 }

=C2=A0 void deinit() {
=C2=A0 =C2=A0 manager_->destroy(&data_, this->mr_);
=C2=A0 }

=
=C2=A0 const manager_t* manager_;
=
=C2=A0 mutable void* data_;
};

Mingxin Wang

--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
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.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/7f22751b-91d1-4de4-81d2-421046ceb963= %40isocpp.org.
------=_Part_17684_234504532.1508166662513-- ------=_Part_17683_777117230.1508166662511-- .