Sorting vector of QPointers

Question

I have:

std::vector< QPointer<ToDoItem> > items;

and the call to sort:

std::sort(items.begin(), items.end(), custComparFunction)

I am using the custom sorting function:

bool ToDoList::custComparFunc(QPointer<ToDoItem> i1, QPointer<ToDoItem> i2){
    if (i1.data()->getSecsTillDeadline() == i2.data()->getSecsTillDeadline()){
        return i1.data()->getMainText() < i2.data()->getMainText();
    }
    return i1.data()->getSecsTillDeadline() < i2.data()->getSecsTillDeadline();
}

I am trying to sort a vector of QPointers based on the value returned by 'getSecsTillDeadline()' function

but I am getting the error 'must use '.*' or '->*' to call pointer to member function'.

where am I going wrong? the error is in a file predefined_ops.h so I would imagine that there is something in my own code I can change to make this work

the full error is:

C:\Qt\Tools\mingw492_32\i686-w64-mingw32\include\c++\bits\predefined_ops.h:121: error: must use '.*' or '->*' to call pointer-to-member function in '((__gnu_cxx::__ops::_Iter_comp_iter<bool (ToDoList::*)(QPointer<ToDoItem>, QPointer<ToDoItem>)>*)this)->__gnu_cxx::__ops::_Iter_comp_iter<bool (ToDoList::*)(QPointer<ToDoItem>, QPointer<ToDoItem>)>::_M_comp (...)', e.g. '(... ->* ((__gnu_cxx::__ops::_Iter_comp_iter<bool (ToDoList::*)(QPointer<ToDoItem>, QPointer<ToDoItem>)>*)this)->__gnu_cxx::__ops::_Iter_comp_iter<bool (ToDoList::*)(QPointer<ToDoItem>, QPointer<ToDoItem>)>::_M_comp) (...)'
     { return bool(_M_comp(*__it1, *__it2)); }
                                          ^

Answer 1

It seems form the error message that custComparFunction is a non-static member function in the ToDoItem class. You can't use non-static member functions like "normal" non-member function pointers.

The simplest solution is to make the function a static member function.