built-in predicate

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. When the predicate is called with the first argument unbound, both types of events are defined. The object Monitor must define the event handler methods required by the Event argument.

Modes and number of proofs

define_events(@term, @term, @term, @term, +object_identifier) - one

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:

type_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 "debugger" as a monitor for member/2 messages
% sent to the "list" object:
| ?- define_events(_, list, member(_, _), _ , debugger).

See also

abolish_events/5, current_event/5, before/3, after/3