Class event-tree defines the inheritance hierarchy of event-types. Each node of this tree represents a specific event. The event-tree must be capable to do one operation very quick: telling from to event-type names whether the one is below the other in the tree. For this purpose the event-tree contains a has-table to find a node from an event-type.
Do not use this class directly. It's definition is subject to change. Notably multiple inheritance is studied as a possible extension.
This class has one global predefined object associated to it: @event_tree. This object can be used to examine the inheritance hierarchy of events.
See also event->is_a,
class event_node
and the Events demo program.
<-ids
into event_node
objects.