Nsryjdtyk

I'm trying to write a method for a selection class that I've written that scans though the selection list for the first item that can be cast to a given datatype and returns it (or null if there is none). Unfortunately, my compiler is complaining:

error: undefined reference to `GraphNode* Selection::getFirstItem<GraphNode*>()'

The editor is providing some hints:

warning: instantiation of function 'Selection::getFirstItem<GraphNode *>' required here, but no definition is available

forward declaration of template entity is here

add an explicit instantiation declaration to suppress this warning if 'Selection::getFirstItem<GraphNode *>' is explicitly instantiated in another translation unit

Here is the relevant part of my selection class:

//Selection.h

class Selection : public QObject

{

    QList<QObject*> _items;

public:



    template <class T> T getLastItem();

}



//Selection.cpp

template <class T> T Selection::getLastItem()

{

    for (QObject* obj: _items)

    {

        T val = qobject_cast<T>(obj);

        if (val)

            return val;

    }

    return nullptr;

}

And this is the line where the error occurs:

GraphNode* top = _curScene->selection().getLastItem<GraphNode*>();

Is there a way to write this so that the compiler is able to find the implementation of my getLastItem() method?