42     void setCallback(ChangeNotifyCallback callback) {

    42     void setCallback(ChangeNotifyCallback callback) {

    43         m_callback = callback;

    43         m_callback = callback;

    44     }

    44     }

    45 protected:

    45 protected:

    46     void notify (double oldVal, double newVal) {

    46     void notify (double oldVal, double newVal) {

    48             m_callback (oldVal, newVal);

    48             m_callback (oldVal, newVal);

    49         }

    49         }

    50     }

    50     }

    51 private:

    51 private:

    52     ChangeNotifyCallback m_callback;

    52     ChangeNotifyCallback m_callback;