Logtalk reference manual
Built-in predicate: define_events/5
Contents > Reference Manual > Built-in Predicates > define_events/5

## define_events/5

#### Description

    define_events(Event, Object, Message, Sender, Monitor)

Defines a new set of events. The two types of events are represented by the atoms `before` and `after` The object `Monitor` must define the event handler methods required by the `Event` argument.

#### Template and modes

    define_events(@event, @object_identifier, @callable, @object_identifier, +object_identifier)

#### Errors

Event is neither a variable nor a valid event identifier:
  `type_error(event, Event)`
Object is neither a variable nor a valid object identifier:
  `type_error(object_identifier, Object)`
Message is neither a variable nor a callable term:
  `type_error(callable, Message)`
Sender is neither a variable nor a valid object identifier:
  `type_error(object_identifier, Sender)`
Monitor is a variable:
  `instantiation_error`
Monitor is neither a variable nor a valid object identifier:
  `existence_error(object_identifier, Monitor)`
Monitor does not define the required `before/3` method:
  `existence_error(procedure, before/3)`
Monitor does not define the required `after/3` method:
  `existence_error(procedure, after/3)`

#### Examples

    | ?- define_events(_, list, member(_, _), _ , debugger).