src/swipl-devel/packages/xpce/man/refmanual/md/event_tree.md

In rswipl: Embed 'SWI'-'Prolog'

class event_tree {#class-event_tree}

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.

@see event->is_a @see class event @see class event_node @see object->recogniser

Instance variables {#class-event_tree-instvars}

• event_tree-table: hash_table Hash_table object mapping event<-ids into event_node objects.

Send methods {#class-event_tree-send}

• event_tree->root: event_node @see !already_has_root

rswipl documentation built on June 16, 2026, 5:07 p.m.