Abstract classes are exported for developers that want to extend them, they are not useful to casual users. Layouts get a LogEvent passed down from an Appender, and format them for output. How this formatting works exactly varies widely. For example for file or console output the log event is usually formatted into a single character line.
Layouts are instantiated with <LayoutSubclass>$new(). For a description of
the arguments to this function please refer to the Fields section.
format_event(event)format a LogEvent
Other Layouts: LayoutDbi,
LayoutFormat, LayoutGlue,
LayoutJson