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event_retrieve(+EventHandle, -Goal, -Module)

Given the handle with which an event is associated, retrieve the event goal and module
An event handle
A free variable or goal to unify
A free variable or module name


The goal associated with an event handle, created using event_create/3, is retrieved using this predicate. It also returns the context module in which the event was created (and where the goal should be called).

Like event creation, retrieval of the goal produces a copy of the goal. As a result, if the goal contains variables, they lose their identity and are replaced with fresh ones.

If the event was disabled, the goal 'true' is retrieved instead of the original goal.

Modes and Determinism


(4) instantiation fault
EventHandle is un-instantiated
(5) type error
EventHandle is not a handle


    ?- event_create(writeln('Hello world!'), [], Event),
    	event_retrieve(Event, EventGoal, Module).

    Event = $&(event,"371bqn")
    EventGoal = writeln('Hello world!')
    Module = eclipse
    Yes (0.00s cpu)

See Also

event_create / 3, event / 1, event_after / 2, event_after / 3, event_after_every / 2, set_event_handler / 2, current_after_events / 1, cancel_after_event / 2, is_event / 1, event_disable / 1, event_enable / 1