bb_get/3 /MINERVA/Manual/Reference/Predicates/blackboard/bb

bb_get/3

gets the term which is stored with a certain key in a blackboard.

Blackboards are collections of (Key,Value) tuples. bb_get/3 allows to inspect the tuples of a blackboard.

If Key is a ground term hashing will be used to retrieve the associated Value entry. If there is a tuple (Key,Value) in the blackboard Value will be unified with Term. Otherwise the predicate fails.
If Key is not a ground term, by backtracking all tuples (K,V) of the blackboard will be retrieved and unified with the term (Key,Value).

Board                  blackboard
Key                    ground term
Term                   term

Assume there exists a blackboard 'blackboard' with elements (100, abc), (101, element101), (102, abc).

bb_get(blackboard,102, abc).	Succeeds.
bb_get(blackboard, 100, X).	Succeeds with substitution X <- abc
bb_get(blackboard, Key, abc).	Succeeds twice with substitution Key <- 100 Key <- 102
bb_get(blackboard, Key, Term).	Succeeds three times with substitution X <- abc X <- element101 X <- abc

This predicate is not part of the ISO-Prolog Standard.