Log::message is a generic message storage mechanism. it allows you to store messages on a stack -- either shared or private -- and assign meta-data to it. some meta-data will automatically be added for you, like a timestamp and a stack trace, but some can be filled in by the user, like a tag by which to identify it or group it, and a level at which to handle the message (for example, log it, or die with it)

log::message also provides a powerful way of searching through items by regexes on messages, tags and level.