signal/slots in template classes

[killkolor]

hi!

i have a couple of template classes and let them inherit from QObject to use the signal/slot observer pattern. at compile-time though i get a whole lot of linker errors. is it possible to use qt's signal/slot mechanism in template classes? if not, are there alternatives?
i'll give some samples out of my code and one of the linker errors to make things a bit clearer:

template <class T>
class ColladaReference :
	public QObject
{
	Q_OBJECT
public:
	ColladaReference(){};
	ColladaReference(T *ref){reference = ref;}
	~ColladaReference(){};
 
	void deleteReference();
 
private:
	T *reference;
};
==========
template <class T>
class ColladaRepresentation :
	public QObject
{
	Q_OBJECT
public:
	ColladaRepresentation(){representation = NULL;}  // constructor
	ColladaRepresentation(T *rep){representation = rep;}  // constructor with collada ptr
 
	void setRepresentation(T *rep){representation = rep;}
public slots:
	void deleteRepresentation();
signals:
	void representationDeleted(){};
private:
	T * representation;
};
====================
typedef ColladaRepresentation<domGeometry> GeometryRepresentation;
typedef ColladaReference<domInstance_geometry> GeometryReference;
====================
GeometryReference *geometryReference = new GeometryReference(instanceGeometry);
GeometryRepresentation *geometryRepresentation = new GeometryRepresentation(geometryNode[k]);
connect(geometryRepresentation, SIGNAL(representationDeleted()), 								geometryReference, SLOT(deleteReference()));
=================

template <class T>
class ColladaReference :
	public QObject
{
	Q_OBJECT
public:
	ColladaReference(){};
	ColladaReference(T *ref){reference = ref;}
	~ColladaReference(){};

	void deleteReference();

private:
	T *reference;
};
==========
template <class T>
class ColladaRepresentation :
	public QObject
{
	Q_OBJECT
public:
	ColladaRepresentation(){representation = NULL;}  // constructor
	ColladaRepresentation(T *rep){representation = rep;}  // constructor with collada ptr

	void setRepresentation(T *rep){representation = rep;}
public slots:
	void deleteRepresentation();
signals:
	void representationDeleted(){};
private:
	T * representation;
};
====================
typedef ColladaRepresentation<domGeometry> GeometryRepresentation;
typedef ColladaReference<domInstance_geometry> GeometryReference;
====================
GeometryReference *geometryReference = new GeometryReference(instanceGeometry);
GeometryRepresentation *geometryRepresentation = new GeometryRepresentation(geometryNode[k]);
connect(geometryRepresentation, SIGNAL(representationDeleted()), 								geometryReference, SLOT(deleteReference()));
=================

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Error 3 error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __thiscall ColladaReference<class domInstance_geometry>::metaObject(void)const " (?metaObject@?$ColladaReference@VdomInstance_geome try@@@@UBEPBUQMetaObject@@XZ) colladaLoader.obj

[e8johan]

Have you had a look at this article? http://doc.trolltech.com/qq/qq15-academic.html

[Brandybuck]

No, it's not generally possible to use signal/slots in template classes. That's because MOC/UI are pre-processors but the actual classes don't get generated until compile time. This is the one disadvantage of signal/slots I've run across.