c++ - 将 mem_fun_ref 与 boost::shared_ptr 一起使用

Question

遵循 this page 的建议，我试图让 shared_ptr 调用 IUnknown::Release()而不是删除:

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)' : could not 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)' : could not 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))' : could not 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))' : could not 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

我不知道该怎么做。我有限的模板/仿函数知识促使我尝试

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

但是没有用。有什么想法吗？

Answer 1

std::mem_fun_ref 不支持 stdcall 调用转换以及可用于指针的 std::mem_fun。

您可以改用 boost::mem_fn。你should define BOOST_MEM_FN_ENABLE_STDCALL 使用 COM 方法。

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

并且由于您的对象具有内部引用计数，您可以考虑使用 boost::intrusive_ptr相反。