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erase(+DBRef)

Succeeds if the database reference DBRef designates a term recorded in the indexed database and this term is successfully erased.
+DBRef
A database reference.

Description

The database reference DBRef must refer to a term that has been recorded in the indexed database. Database references can be obtained from the predicates recorda/3, recordz/3 and recorded/3. If the referenced term has already been erased, erase/1 fails. Backtracking through calls of erase/1 does not undo an erasure. Note that database references are not integers.

Fail Conditions

Fails if DBRef refers to an already erased record.

Resatisfiable

No.

Exceptions

(4) instantiation fault
DBRef is not instantiated.
(5) type error
DBRef is not a database reference.

Examples

   Success:
   [eclipse]: recordz(whiskey, jameson, _),
   recordz(whiskey, glenfiddich, Ref),
   recordz(whiskey, dimple, _),
   erase(Ref).
   Ref = 98538
   yes.
   [eclipse]: recorded(whiskey, L, _).
   L = jameson     More? (;)
   L = dimple     More? (;)
   no (more) solution.
   Fail:
   [eclipse]: recorded(whiskey,_,R), !, erase(R), erase(R).
   no (more) solution.
   Error:
   erase(Var).                            (Error 4)
   erase(123).                            (Error 5)

See Also

erase_all / 1, recorda / 3, recordz / 3, recorded / 3, referenced_record / 2