public:
inline SignedId(int _id = 0) { id = _id; }
inline qint32 toInt() const { return id; }
+ inline bool isValid() const { return id > 0; }
inline bool operator==(const SignedId &other) const { return id == other.id; }
inline bool operator!=(const SignedId &other) const { return id != other.id; }