fields builder

include/sp/default/DefaultPacket.h

@@ -13,4 +13,10 @@ using PacketMessage = Message<
 	option::Handler<PacketHandler>								// add dispatch() operation
 	>;
 
+#define DeclarePacket(packetName) class packetName##Packet : public sp::MessageBase<sp::PacketMessage,\
+	sp::option::StaticNumIdImpl<packetName>,		\
+							sp::option::DispatchImpl<packetName##Packet>,	\
+							sp::option::FieldsImpl<packetName##Fields>		\
+							> {}
+
 }  // namespace sp