使用mem_fun_ref和boost :: shared_ptr [英] Using mem_fun_ref with boost::shared_ptr

问题描述

按照此网页的建议，我想获得shared_ptr调用 IUnknown :: Release（），而不是删除：

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

错误C2784：'std :: const_mem_fun1_ref_t< _Result，_Ty，_Arg > std :: mem_fun_ref（ Result（ _thiscall _Ty :: *）（_Arg）const）'：无法推导出'em'结果的模板参数（ _thiscall _Ty :: * （ Arg）const'from'ULONG（ _cdecl IUnknown :: *）（void）'

错误C2784：'std :: const_mem_fun_ref_t& _Result，_Ty> std :: mem_fun_ref（结果（ _thiscall _Ty :: *）（void）const）'：无法推导出'em'结果的模板参数（ _thiscall _Ty： ：*）（void）const'from'ULONG（__cdecl IUnknown :: *）（void）'

错误C2784：'std :: mem_fun1_ref_t <_Result， _Arg> std :: mem_fun_ref（ result（ _thiscall _Ty :: *）（_Arg））'：无法推导出'em'结果的模板参数（ _thiscall _Ty :: * （ Arg）'from'ULONG（ _cdecl IUnknown :: *）（void）'

错误C2784：'std :: mem_fun_ref_t< _Result ，_Ty> std :: mem_fun_ref（ _thiscall _Ty :: *）（void））'：无法推导出'em'结果的模板参数（ _thiscall _Ty :: * ）void''''''''''''''''''''''''''''''''需要2个参数

我不知道该怎么做。我有限的模板/函子知识让我尝试

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

但没有效果。任何想法？

解决方案

调用约定规范不是一个问题吗？这是否可以？

  void iUnk_delete（IUnknown * u）{
 u-> 
} 
 
 
 return shared_ptr< IDirectDrawSurface>（dds，iUnk_delete）; 
  

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

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

I have no idea what to make of this. My limited template/functor knowledge led me to try

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

But to no avail. Any ideas?

解决方案

Isn't the calling convention specifier a problem? Would this be OK?

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


return shared_ptr<IDirectDrawSurface>(dds, iUnk_delete);

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