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

In rswipl: Embed 'SWI'-'Prolog'

class recogniser {#class-recogniser}

Class recogniser is an almost empty super-class. It's main purpose is to serve as a type-check for it's sub-classes.

A recogniser is an object that maps a user event onto an action. The events origins from the window on which it occurred and is dispatched by the dispatching behaviour defined by device ->event.

A recogniser may be attached to a graphical object using graphical ->recogniser' or it may be used from a redefinedgraphical ->event` method. Multiple recognisers may be combined to a single entity using class handler_group.

@see graphical->event @see class event @see topic Handling Events @see object->recogniser @see class interceptor @see object<-all_recognisers @see object->prepend_recogniser

Instance variables {#class-recogniser-instvars}

• recogniser<->active: bool Recognisers can be made inactive using ->active: @off. The method ->event fails for inactive recognisers.

Send methods {#class-recogniser-send}

• recogniser->event: event Process an event. The method defined at the level of class recogniser itself simply fails.

• recogniser->initialise Create a recogniser object. Initialises ->active to @on. Creating instances of this class is no common use.

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