\returns key of the packet
\throws PacketTypeNotRegistered if the packet type is not found in the registry.
*/
- static typename Tag::key_t key(Packet packet);
+ static typename Tag::key_t key(Packet const & packet);
/** \brief Find key of a packet
href="http://www.boost.org/libs/optional/doc/optional.html">boost::optional</a> or
an unbound optional, if the key is not found.
*/
- static typename boost::optional<typename Tag::key_t> key(Packet packet, NoThrow_t);
+ static typename boost::optional<typename Tag::key_t> key(Packet const & packet, NoThrow_t);
/** \brief Lookup a packet by it's key