I'm trying to create an object for use for QML integration.

If I uncomment the marked code, I get compilation errors:
Qt Code: 
  1. // header
  2. #ifndef MY_QML_INTERFACE_H
  3. #define MY_QML_INTERFACE_H
  4.  
  5. #include <QObject>
  6. #include <QDateTime>
  7.  
  8. class MyQmlInterface : public QObject
  9. {
  10. 	Q_OBJECT
  11.  
  12. public:	
  13.  
  14. 	Q_PROPERTY(QString singleValue READ singleValue WRITE setSingleValue NOTIFY singleValueChanged);
  15.  
  16. 	const QString &singleValue() const;
  17. 	void setSingleValue(const QString &newSingleValue);
  18.  
  19. 	/* THIS CODE WON't COMPILE
  20. 	Q_INVOKABLE QDateTime getCurrentDateTime() const {
  21.          return QDateTime::currentDateTime();
  22. 		 */
  23.  
  24. signals:
  25. 	void singleValueChanged();
  26. private:
  27. 	QString mSingleValue;
  28. };
  29.  
  30. #endif
  31.  
  32. // Cpp
  33. #include "MyQmlInterface.h"
  34.  
  35. const QString &MyQmlInterface::singleValue() const 
  36. {
  37. 	return mSingleValue;
  38. }
  39.  
  40. void MyQmlInterface::setSingleValue(const QString &newSingleValue)
  41. {
  42. 	if (newSingleValue == mSingleValue)
  43. 		return;
  44. 	mSingleValue = newSingleValue;
  45. 	emit singleValueChanged();
  46. }
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Any idea why this doesn't work?