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# event_enable(+EventHandle)

Enable the given event

EventHandle
  An event handle

## Description

The given event is (re-)enabled. Since events are enabled by default, this only makes sense if the event had been previously disabled.

A disabled events behaves as if its handler was the goal 'true':

- Retrieving the goal using event_retrieve/3 returns 'true'
- When the event is raised (e.g. posted via event/1), nothing happens
- If the event gets disabled after it was raised, but before its handler execution has started, handler execution will be suppressed.

Note that disabling and enabling events are nonlogical operations which are not undone on backtracking.

### Modes and Determinism

- event_enable(+) is det

### Exceptions

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

## Examples

        ?- event_create(writeln(hello), [], E),
           event_disable(E), writeln(disabled),
           event(E),	% does nothing
           event_enable(E), writeln(enabled),
           event(E).
        disabled
        enabled
        hello

## See Also

event_create / 3, event / 1, event_disable / 1, event_retrieve / 3