converting value objects to/from QVariant

refs #81

src/blackmisc/pqfrequency.h

@@ -29,6 +29,15 @@ namespace BlackMisc
              */
             CFrequency(double value, const CFrequencyUnit &unit) : CPhysicalQuantity(value, unit) {}
 
+            /*!
+             * \brief Virtual method to return QVariant, used with DBUS QVariant lists
+             * \return
+             */
+            virtual QVariant toQVariant() const
+            {
+                return QVariant::fromValue(*this);
+            }
+
             /*!
              * \brief Virtual destructor
              */