Function: REPLACE-SLOT-INDEX

Source

(defun replace-slot-index (rucksack class slot index-spec unique-p)
  ;; We have an index but need a different one now.  This requires
  ;; some care because we need to re-index all objects from the old
  ;; index.
  (let ((current-index (rucksack-slot-index rucksack class slot))
        (new-index (rucksack-add-slot-index rucksack class slot
                                            index-spec
                                            unique-p
                                            :errorp nil)))
    ;; Re-index all objects for the new index.
    ;; DO: This re-indexing can cause an error (e.g. if the old
    ;; index has non-unique keys, the new index has unique keys
    ;; and some keys occur more than once).  We need to handle
    ;; that error here and offer some decent restarts (e.g.
    ;; remove the index entirely, or go back to the old index).
    (map-index current-index
               (lambda (slot-value object)
                 (index-insert new-index slot-value object)))
    ;; We don't need to remove the old index explicitly, because
    ;; RUCKSACK-ADD-SLOT-INDEX already did that for us.
    ))