Class::EHierarchy is intended for use as a base class for custom objects. The objects need one or more of the following features: orderly bottom-up destruction of objects, opaque objects, class-based access restrictions for properties and methods, primitive strict property type awareness, and alias-based object retrieval.
tcpdump prints a description of the contents of packets on a network interface which match a given boolean expression. It can also be run with the -w flag, which causes it to save the packet data to a file for later analysis, and/or with the -r flag, which causes it to read from a saved packet file rather than to read packets from a network interface. In all cases, only packets which match the expression will be processed by tcpdump. tcpdump logs more than just TCP, IP, or ethernet packets, but has a whole suite of decoders, including ones for USB.