模板函数，用于在模板化对象上执行成员回调，而无需提供其实例

一些上下文...

• 我有一张包含对象向量作为值的地图。
• 每个向量都包含专用类型的对象。
• 映射的键是表示每种类型的枚举的值，EnumObjType
• 我收到包含EnumObjType和ObjID的事件。

我正在尝试构建一个模板函数来处理任何类型的对象，我面临的挑战是这些对象 ID 是使用专用类的方法访问的。为了解决这个问题，我正在尝试向我的模板函数添加一个参数，该参数将是调用以获取SpecializedObj的 ID 的函数。

模板函数调用如下所示：

bool processEvent<SpecializedObj>(iEvent, iObjMap, &SpecializedObj::getSpecializedId);

定义 ：

template<typename ObjType>
bool processEvent(MyEvent* iEvent,  ObjMap* iObjMap, std::function<unsigned int(void)> iObjIdCall)
{
// Reach the corresponding ObjType vector
ObjMap::iterator it =  iObjMap->find(iEvent->getObjType());
std::vector<BaseObject*> wObjVector = it->second;
// Iterate over the vector's range  
for(BaseObject* wBaseObjPtr : wObjVector)
{
// Cast into SpecializedObj
ObjType* wSpecializedObjPtr = dynamic_cast<ObjType*>(wBaseObjPtr);
// Test dynamic_cast result
if(!wSpecializedObjPtr) {return false;}
std::function<unsigned int(void)> callback = std::bind(iObjIdCall,*wSpecializedObjPtr);
// Check if the SpecializedObjPtr's ID matches the event's DeviceId
if(callback() != iEvent->getDeviceId()) {return false;}
// work on SpecializedObj
// ...
return true
}

在我眼中相当神秘的错误之下：

11>C:Program Files (x86)Microsoft Visual Studio 11.0VCincludefunctional(514) : error C2664: 'std::_Func_class<_Ret>::_Set' : cannot convert parameter 1 from '_Myimpl *' to 'std::_Func_base<_Rx> *'
11>        with
11>        [
11>            _Ret=const unsigned int
11>        ]
11>        and
11>        [
11>            _Rx=const unsigned int
11>        ]
11>        Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
11>        C:Program Files (x86)Microsoft Visual Studio 11.0VCincludefunctional(514) : see reference to function template instantiation 'void std::_Func_class<_Ret>::_Do_alloc<_Myimpl,_Fret(__thiscall SpecializedObj::* const &)(void) const,_Alloc>(_Fty,_Alloc)' being compiled
11>        with
11>        [
11>            _Ret=const unsigned int,
11>            _Fret=const unsigned int,
11>            _Alloc=std::allocator<std::_Func_class<const unsigned int>>,
11>            _Fty=const unsigned int (__thiscall SpecializedObj::* const &)(void) const
11>        ]
11>        C:Program Files (x86)Microsoft Visual Studio 11.0VCincludefunctional(514) : see reference to function template instantiation 'void std::_Func_class<_Ret>::_Do_alloc<_Myimpl,_Fret(__thiscall SpecializedObj::* const &)(void) const,_Alloc>(_Fty,_Alloc)' being compiled
11>        with
11>        [
11>            _Ret=const unsigned int,
11>            _Fret=const unsigned int,
11>            _Alloc=std::allocator<std::_Func_class<const unsigned int>>,
11>            _Fty=const unsigned int (__thiscall SpecializedObj::* const &)(void) const
11>        ]
11>        C:Program Files (x86)Microsoft Visual Studio 11.0VCincludefunctional(514) : see reference to function template instantiation 'void std::_Func_class<_Ret>::_Reset_alloc<_Fret,SpecializedObj,std::allocator<_Ty>>(_Fret (__thiscall SpecializedObj::* const )(void) const,_Alloc)' being compiled
11>        with
11>        [
11>            _Ret=const unsigned int,
11>            _Fret=const unsigned int,
11>            _Ty=std::_Func_class<const unsigned int>,
11>            _Alloc=std::allocator<std::_Func_class<const unsigned int>>
11>        ]
11>        C:Program Files (x86)Microsoft Visual Studio 11.0VCincludefunctional(514) : see reference to function template instantiation 'void std::_Func_class<_Ret>::_Reset_alloc<_Fret,SpecializedObj,std::allocator<_Ty>>(_Fret (__thiscall SpecializedObj::* const )(void) const,_Alloc)' being compiled
11>        with
11>        [
11>            _Ret=const unsigned int,
11>            _Fret=const unsigned int,
11>            _Ty=std::_Func_class<const unsigned int>,
11>            _Alloc=std::allocator<std::_Func_class<const unsigned int>>
11>        ]
11>        C:Program Files (x86)Microsoft Visual Studio 11.0VCincludefunctional(675) : see reference to function template instantiation 'void std::_Func_class<_Ret>::_Reset<const unsigned int,SpecializedObj>(_Fret (__thiscall SpecializedObj::* const )(void) const)' being compiled
11>        with
11>        [
11>            _Ret=const unsigned int,
11>            _Fret=const unsigned int
11>        ]
11>        C:Program Files (x86)Microsoft Visual Studio 11.0VCincludefunctional(675) : see reference to function template instantiation 'void std::_Func_class<_Ret>::_Reset<const unsigned int,SpecializedObj>(_Fret (__thiscall SpecializedObj::* const )(void) const)' being compiled
11>        with
11>        [
11>            _Ret=const unsigned int,
11>            _Fret=const unsigned int
11>        ]
11>        C:MyProjectObjUpdater.cpp(29) : see reference to function template instantiation 'std::function<_Fty>::function<const unsigned int(__thiscall SpecializedObj::* )(void) const>(_Fx &&)' being compiled
11>        with
11>        [
11>            _Fty=const unsigned int (void),
11>            _Fx=const unsigned int (__thiscall SpecializedObj::* )(void) const
11>        ]
11>        C:MyProjectObjUpdater.cpp(29) : see reference to function template instantiation 'std::function<_Fty>::function<const unsigned int(__thiscall SpecializedObj::* )(void) const>(_Fx &&)' being compiled
11>        with
11>        [
11>            _Fty=const unsigned int (void),
11>            _Fx=const unsigned int (__thiscall SpecializedObj::* )(void) const
11>        ]

当我以前使用回调时，我总是知道它将与哪个对象实例相关联，所以我会将其作为函数参数传递给std::bind(&Foo::func, fooObj)但它似乎在这里不适合我。

编辑： 我正在使用 Visual Studio 2012 v110 工具集