namespace OVR {
  class DeviceBase;
  class DeviceHandle;
  class DeviceInfo;
  class DeviceManager;
  class HMDDevice;
  class HMDInfo;
  class Message;
  class MessageHandler;
  class SensorDevice;
  class SensorInfo;
  class SensorFusion;

  template<class T> class DeviceEnumerator;
  template<class T> class Ptr;
};