Next: mpg-ref-integer, Previous: mpg-ref-initialization, Up: mpg-bpr [Contents][Index]
instance/2
instance(+Ref, -Term)
Unifies Term with the most general instance of the dynamic clause or recorded term indicated by the database reference Ref.
db_reference, must be nonvar
term
Ref must be instantiated to a database
reference to an existing clause or recorded term. instance/2
is
not sensitive to the source module and can be used to access any
clause, regardless of its module.
instantiation_error
if Ref is not instantiated
type_error
if Ref is not a syntactically valid database reference
existence_error
if Ref is a syntactically valid database reference but does not refer to an existing clause or recorded term.
| ?- assert(foo:bar,R). R = '$ref'(771292,1) | ?- instance('$ref'(771292,1),T). T = (bar:-true) | ?- clause(H,B,'$ref'(771292,1)). no | ?- clause(foo:H,B,'$ref'(771292,1)). H = bar, B = true