before/3
Description
before(Object, Message, Sender)
User-defined method for handling before events. This method is
declared in the monitoring built-in protocol
as a public predicate and automatically called by the runtime for messages
sent using the (::)/2 control construct from within
objects compiled with the events flag set to allow.
Note that you can make this predicate scope protected or private by using,
respectively, protected or private implementation
of the monitoring protocol.
Modes and number of proofs
before(?object_identifier, ?callable, ?object_identifier) - zero_or_more
Errors
(none)
Examples
:- object(...,
implements(monitoring),
...).
% write a log message when a message is sent:
before(Object, Message, Sender) :-
writeq(Object), write('::'), writeq(Message),
write(' from '), writeq(Sender), nl.
See also