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erase(+DBRef)

Succeeds if the database reference DBRef designates a term recorded in the record 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 record 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 an erased term can still be retrieved via the database reference, but it can no longer be found by lookup under the recording-key.

Modes and Determinism

Fail Conditions

Fails if DBRef refers to an already erased record

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 = $&(dbref,"370h9z")
   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, is_handle / 1, recorda / 3, recordz / 3, recorded / 3, referenced_record / 2