Next: mpg-ref-unknown_predicate_handler, Previous: mpg-ref-univ, Up: mpg-bpr [Contents][Index]
unknown/2
developmentunknown(-OldAction, +NewAction)
Unifies OldAction with the current action on unknown procedures,
i.e. the current value of the unknown
Prolog flag, sets the
current action to NewAction, and prints a message about the
change.
one of [error,fail,trace,warning]
one of [error,fail,trace,warning]
, must be nonvar
This is merely a front-end to the unknown
Prolog flag, which see.
Note that:
| ?- unknown(Action, Action).
just returns Action without changing it.
Procedures that are known to be dynamic just fail when there are no clauses for them.
instantiation_error
type_error
domain_error
Invalid NewAction.
Undefined Predicates, ref-ere, ref-lps-flg.