Template methods with function pointers

[canderse]

I am beginning to use templates alot (in visual studio 2008) but I
writing this simple template
that has a method which takes a function pointer as an argument and i
cant figure out why the will not compile

LONG __cdecl FilterListProc(LPVOID Item1,LPVOID Item2,LPVOID pParam =
NULL);

template<class TItemList,class TItemData>
class CFiltredListImpl
{
private:
class vaiables anf methods
...
public:
BOOL Filter(LONG (__cdecl *FilterProc)(LPVOID,LPVOID,LPVOID),LPVOID
lpPram = NULL)
{
return TRUE;
};

};

idearly it would like the function to look like this

LONG __cdecl FilterListProc(LPVOID Item1,LPVOID Item2,LPVOID pParam =
NULL);

template<class TItemList,class TItemData>
class CFiltredListImpl
{
private:
class vaiables anf methods
...
public:
BOOL Filter(LONG (__cdecl *FilterProc)(LPVOID,LPVOID,LPVOID) =
FilterListProc ,LPVOID lpPram = NULL)
{
return TRUE;
};

};

or even better it would be better if I could write it like this

template<TItemData>
LONG __cdecl FilterListProc(TItemData & Item1,TItemData & Item2,LPVOID
pParam = NULL);

template<class TItemList,class TItemData>
class CFiltredListImpl
{
private:
class vaiables anf methods
...
public:
BOOL Filter(LONG (__cdecl *FilterProc)(TItemData &,TItemData,LPVOID)
= FilterListProc ,LPVOID lpPram = NULL)
{
return TRUE;
};

};


My first question is why will the first version compile and my second
is the other two implementation feasible

Your help would be apreciated

Thanks Christian Arild Stær Andersen

 

[canderse]

I did get it to compile with this

template<TItemData>
LONG __cdecl FilterListProc(TItemData & Item1,TItemData & Item2,LPVOID
pParam = NULL);

template<class TItemList,class TItemData>
class CFiltredListImpl
{
private:
class vaiables anf methods
...
public:
BOOL Filter(LONG (__cdecl *FilterProc)(TItemData &,TItemData
& ,LPVOID),LPVOID lpPram = NULL)
{
return TRUE;
};

};

 

[dascandy]

I did get it to compile with this

template<TItemData>
LONG __cdecl FilterListProc(TItemData & Item1,TItemData & Item2,LPVOID
pParam = NULL);

template<class TItemList,class TItemData>
class CFiltredListImpl
{
        private:
        class vaiables anf methods
        ...
        public:
        BOOL Filter(LONG (__cdecl *FilterProc)(TItemData &,TItemData
& ,LPVOID),LPVOID lpPram = NULL)
        {
                return TRUE;
        };

};

The second misses an ampersand in front of the function name, I'm not
sure if that's all.

The third misses both the ampersand and the template instantiation
parameters, which means that you can't pass the plain template - you
have to pass it as an instantiated function:

BOOL Filter(LONG (__cdecl *FilterProc)(TItemData &,TItemData
& ,LPVOID) = &FilterListProc<TItemData>,LPVOID lpPram = NULL)

which should work.

Good luck.