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使用std::bind和__stdcall函数

c++c++11stdcallstdbind
4
如何在目前的实现中使用std :: bind（而不是boost :: bind）处理__stdcall函数，或者这是否可能？当我尝试编译以下示例时：
std::function<LRESULT __stdcall(int, WPARAM, LPARAM)> func;
func = std::bind(&EventListener::myhook, this, std::placeholders::_1, 
                 std::placeholders::_2, std::placeholders::_3);

或者使用声明函数的方式：

std::function<LRESULT(int, WPARAM, LPARAM> func;

给我产生了奇怪的构建输出（如下所示）。有一种非常恶劣的方法可以使其编译:
decltype(std::bind(&EventListener::myhook, nullptr, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3))* HookCallbackPointer;
    HookCallbackPointer proc;

proc = reinterpret_cast<HookCallbackPointer>
    (&std::bind(&EventListener::myhook, this,
                std::placeholders::_1,
                std::placeholders::_2,
                std::placeholders::_3));

但是它不允许我像这样调用函数 (*proc)(0,0,0);，这很遗憾。所有这些情况都是因为该函数 - myhook - 声明为 __stdcall。当然我可以编写一个肮脏的汇编hack，在函数末尾推送4个dword，这将“使”它成为__stdcall，但我对此并不确定，而且这种方法更加不可取。

1>D:\bin\Visual Studio\VC\include\xrefwrap(431): error C2440: 'return' : cannot convert from 'std::_Do_call_ret<_Forced,_Ret,_Funx,_Btuple,_Ftuple>::type' to 'LRESULT'
1>          with
1>          [
1>              _Forced=false,
1>              _Ret=void,
1>              _Funx=__w64 long (__stdcall EventListener::* )(int,WPARAM,LPARAM),
1>              _Btuple=std::tuple<EventListener *,std::_Ph<1>,std::_Ph<2>,std::_Ph<3>>,
1>              _Ftuple=std::tuple<int &,WPARAM &,LPARAM &,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>
1>          ]
1>          Expressions of type void cannot be converted to other types
1>          D:\bin\Visual Studio\VC\include\functional(239) : see reference to function template instantiation '_Ret std::_Callable_obj<_Ty>::_ApplyX<_Rx,int,__w64 unsigned int,__w64 long>(_V0_t &&,_V1_t &&,_V2_t &&)' being compiled
1>          with
1>          [
1>              _Ret=LRESULT,
1>              _Ty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>,
1>              _Rx=LRESULT,
1>              _V0_t=int,
1>              _V1_t=WPARAM,
1>              _V2_t=LPARAM
1>          ]
1>          D:\bin\Visual Studio\VC\include\functional(239) : see reference to function template instantiation '_Ret std::_Callable_obj<_Ty>::_ApplyX<_Rx,int,__w64 unsigned int,__w64 long>(_V0_t &&,_V1_t &&,_V2_t &&)' being compiled
1>          with
1>          [
1>              _Ret=LRESULT,
1>              _Ty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>,
1>              _Rx=LRESULT,
1>              _V0_t=int,
1>              _V1_t=WPARAM,
1>              _V2_t=LPARAM
1>          ]
1>          D:\bin\Visual Studio\VC\include\functional(239) : while compiling class template member function 'LRESULT std::_Func_impl<_Callable,_Alloc,_Rx,_V0_t,_V1_t,_V2_t>::_Do_call(_V0_t &&,_V1_t &&,_V2_t &&)'
1>          with
1>          [
1>              _Callable=_MyWrapper,
1>              _Alloc=std::allocator<std::_Func_class<LRESULT,int,WPARAM,LPARAM>>,
1>              _Rx=LRESULT,
1>              _V0_t=int,
1>              _V1_t=WPARAM,
1>              _V2_t=LPARAM
1>          ]
1>          D:\bin\Visual Studio\VC\include\functional(516) : see reference to class template instantiation 'std::_Func_impl<_Callable,_Alloc,_Rx,_V0_t,_V1_t,_V2_t>' being compiled
1>          with
1>          [
1>              _Callable=_MyWrapper,
1>              _Alloc=std::allocator<std::_Func_class<LRESULT,int,WPARAM,LPARAM>>,
1>              _Rx=LRESULT,
1>              _V0_t=int,
1>              _V1_t=WPARAM,
1>              _V2_t=LPARAM
1>          ]
1>          D:\bin\Visual Studio\VC\include\functional(516) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t,_V1_t,_V2_t>::_Do_alloc<_Myimpl,_Ty,_Alloc>(_Fty &&,_Alloc)' being compiled
1>          with
1>          [
1>              _Ret=LRESULT,
1>              _V0_t=int,
1>              _V1_t=WPARAM,
1>              _V2_t=LPARAM,
1>              _Ty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>,
1>              _Alloc=std::allocator<std::_Func_class<LRESULT,int,WPARAM,LPARAM>>,
1>              _Fty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>
1>          ]
1>          D:\bin\Visual Studio\VC\include\functional(516) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t,_V1_t,_V2_t>::_Do_alloc<_Myimpl,_Ty,_Alloc>(_Fty &&,_Alloc)' being compiled
1>          with
1>          [
1>              _Ret=LRESULT,
1>              _V0_t=int,
1>              _V1_t=WPARAM,
1>              _V2_t=LPARAM,
1>              _Ty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>,
1>              _Alloc=std::allocator<std::_Func_class<LRESULT,int,WPARAM,LPARAM>>,
1>              _Fty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>
1>          ]
1>          D:\bin\Visual Studio\VC\include\functional(516) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t,_V1_t,_V2_t>::_Reset_alloc<_Ty,std::allocator<std::_Func_class<_Ret,_V0_t,_V1_t,_V2_t>>>(_Fty &&,_Alloc)' being compiled
1>          with
1>          [
1>              _Ret=LRESULT,
1>              _V0_t=int,
1>              _V1_t=WPARAM,
1>              _V2_t=LPARAM,
1>              _Ty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>,
1>              _Fty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>,
1>              _Alloc=std::allocator<std::_Func_class<LRESULT,int,WPARAM,LPARAM>>
1>          ]
1>          D:\bin\Visual Studio\VC\include\functional(516) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t,_V1_t,_V2_t>::_Reset_alloc<_Ty,std::allocator<std::_Func_class<_Ret,_V0_t,_V1_t,_V2_t>>>(_Fty &&,_Alloc)' being compiled
1>          with
1>          [
1>              _Ret=LRESULT,
1>              _V0_t=int,
1>              _V1_t=WPARAM,
1>              _V2_t=LPARAM,
1>              _Ty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>,
1>              _Fty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>,
1>              _Alloc=std::allocator<std::_Func_class<LRESULT,int,WPARAM,LPARAM>>
1>          ]
1>          D:\bin\Visual Studio\VC\include\functional(692) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t,_V1_t,_V2_t>::_Reset<_Ty>(_Fty &&)' being compiled
1>          with
1>          [
1>              _Ret=LRESULT,
1>              _V0_t=int,
1>              _V1_t=WPARAM,
1>              _V2_t=LPARAM,
1>              _Ty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>,
1>              _Fty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>
1>          ]
1>          D:\bin\Visual Studio\VC\include\functional(692) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t,_V1_t,_V2_t>::_Reset<_Ty>(_Fty &&)' being compiled
1>          with
1>          [
1>              _Ret=LRESULT,
1>              _V0_t=int,
1>              _V1_t=WPARAM,
1>              _V2_t=LPARAM,
1>              _Ty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>,
1>              _Fty=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>
1>          ]
1>          main.cpp(27) : see reference to function template instantiation 'std::function<_Fty> &std::function<_Fty>::operator =<std::_Bind<_Forced,_Ret,_Fun,_V0_t,_V1_t,_V2_t,_V3_t,_V4_t,_V5_t,<unnamed-symbol>>>(_Fx &&)' being compiled
1>          with
1>          [
1>              _Fty=LRESULT (int,WPARAM,LPARAM),
1>              _Forced=false,
1>              _Ret=void,
1>              _Fun=LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),
1>              _V0_t=EventListener *const ,
1>              _V1_t=std::_Ph<1> &,
1>              _V2_t=std::_Ph<2> &,
1>              _V3_t=std::_Ph<3> &,
1>              _V4_t=std::_Nil,
1>              _V5_t=std::_Nil,
1>              <unnamed-symbol>=std::_Nil,
1>              _Fx=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>
1>          ]
1>          main.cpp(27) : see reference to function template instantiation 'std::function<_Fty> &std::function<_Fty>::operator =<std::_Bind<_Forced,_Ret,_Fun,_V0_t,_V1_t,_V2_t,_V3_t,_V4_t,_V5_t,<unnamed-symbol>>>(_Fx &&)' being compiled
1>          with
1>          [
1>              _Fty=LRESULT (int,WPARAM,LPARAM),
1>              _Forced=false,
1>              _Ret=void,
1>              _Fun=LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),
1>              _V0_t=EventListener *const ,
1>              _V1_t=std::_Ph<1> &,
1>              _V2_t=std::_Ph<2> &,
1>              _V3_t=std::_Ph<3> &,
1>              _V4_t=std::_Nil,
1>              _V5_t=std::_Nil,
1>              <unnamed-symbol>=std::_Nil,
1>              _Fx=std::_Bind<false,void,LRESULT (__stdcall EventListener::* )(int,WPARAM,LPARAM),EventListener *const ,std::_Ph<1> &,std::_Ph<2> &,std::_Ph<3> &,std::_Nil,std::_Nil,std::_Nil>
1>          ]
2
你假设 std::bind 的结果是 std::function<LRESULT __stdcall(int, WPARAM, LPARAM)>。但编译器似乎并不认同。标准规定该类型未指定，那么你怎么知道它会是什么呢？ - Bo Persson
2
延伸Bo所说的，虽然最终调用的函数是__stdcall，但绑定的对象的operator()不一定需要是__stdcall。我不太清楚这在std::bind中是如何处理的，但我不会期望绑定的对象是__stdcall（即operator()的调用约定与内部执行的调用不一定匹配）。 - David Rodríguez - dribeas
1个回答
3

在当前的VS 2012版本中，这是不可能的，也不适用于解决此问题。该想法是绑定成员函数并将其用作钩子过程。正如David Rodriguez和R. Martinho Fernandes（在聊天室 - lounge-C ++中提到）所说，这是不可能的，因为std :: bind会产生对象而不是函数，因此其结果无法作为参数传递给SetWindowsHookEx。

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