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Using mem_fun_ref with boost :: shared_ptr

Following the advice on this page , I'm trying to get a shared_ptr to call IUnknown :: Release () instead of deleting:

IDirectDrawSurface* dds;
... //Allocate dds
return shared_ptr<IDirectDrawSurface>(dds, mem_fun_ref(&IUnknown::Release));

error C2784: 'std :: const_mem_fun1_ref_t <_Result, _Ty, _Arg> std :: mem_fun_ref (_Result (__thiscall _Ty :: *) (_ Arg) const)': Failed to deduce template argument for '_Result (__thiscall _Ty ) (_ Arg) const 'from' ULONG (__cdecl IUnknown :: *) (void) '

error C2784: 'std :: const_mem_fun_ref_t <_Result, _Ty> std :: mem_fun_ref (_Result (__thiscall _Ty :: *) (void) const)': failed to deduce template argument for '_Result (__thiscall _Ty :: *) (void ) const 'from' ULONG (__cdecl IUnknown :: *) (void) '

error C2784: 'std :: mem_fun1_ref_t <_Result, _Ty, _Arg> std :: mem_fun_ref (_Result (__thiscall _Ty :: *) (_ Arg))': failed to deduce template argument for '_Result (__thiscall _Ty :: *) (_ Arg) 'from' ULONG (__cdecl IUnknown :: *) (void) '

error C2784: 'std :: mem_fun_ref_t <_Result, _Ty> std :: mem_fun_ref (_Result (__thiscall _Ty :: *) (void))': failed to deduce template argument for '_Result (__thiscall _Ty :: *) (void) 'from' ULONG (__cdecl IUnknown :: *) (void) '

error C2661: 'boost :: shared_ptr :: shared_ptr': no ​​overloaded function takes 2 arguments

I have no idea what to do about it. My limited knowledge of templates / functors made me try

typedef ULONG (IUnknown::*releaseSignature)(void);
shared_ptr<IDirectDrawSurface>(dds, mem_fun_ref(static_cast<releaseSignature>(&IUnknown::Release)));

But to no avail. Any ideas?

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3 answers


Isn't the calling convention specifier the problem? Will it be okay?



void iUnk_delete(IUnknown* u) {
  u->Release();
}


return shared_ptr<IDirectDrawSurface>(dds, iUnk_delete);
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std::mem_fun_ref

does not support conversion stdcall

as well std::mem_fun

, which you can use for pointers.

You can use instead boost::mem_fn

. You must define BOOST_MEM_FN_ENABLE_STDCALL

to work with COM methods.



shared_ptr<IDirectDrawSurface>( dds, boost::mem_fn(&IUnknown::Release) );

And since your object has an internal reference count, you can use instead boost::intrusive_ptr

.

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I know it might not be what you are after, but just include ATLBase.h and then use the CComPtr template.

Then you just use

 CComPtr< IDirect3DSurface9 > surf;
 pDevice->GetBackBuffer( 0, 0, D3DBACKBUFFER_TYPE_MONO, &surf );

Then you can copy it to another CComPtr and handle all AddRefs and Releases for you. A very useful template class.

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