Hi Hans,
thanks for the promt response! The code I used was from the datastore-manual page 23. When adding the id slot name I run into the following problem: I use cl-prevalence for serialization. When restoring id-objects I do this without-auto-id, so the objects are created having the id slot unbound and assigned later on. This leads to duplicate entries in the class-index and thus inconsitency. I was not sure what happens if there are multiple objects having a unique-index slot set to Nil.
Instead of optionaly binding the id parameter in the constructor I now use an initform that at least binds the auto-id or Nil. Is this a good idea?:
Best regards Klaus
(defvar *id-counter* 0) (defvar *auto-id* T)
(defmacro without-auto-id (&body body) `(let ((*auto-id* Nil)) ,@body))
(defun next-id () (when *auto-id* (incf *id-counter*)))
(defclass id-object () ((id :reader get-id :initform (next-id) :index-type unique-index :index-initargs (:test #'eql) :index-values find-all-id-objects :index-reader find-object-with-id)) (:metaclass indexed-class) (:class-indices (classes :index-type class-index :index-initargs (:index-superclasses t) :slots (id) :index-reader find-all-id-objects-with-class)))
Am Donnerstag, 21. Februar 2008 07:26:02 schrieb Hans Hübner:
Hi Klaus,
the class-index needs to know a slot that it uses for indexing the objects. This slot is the unique ID that the index works on. It must be added to your base class, but as you can see in the corrected example below, that should not be much of a problem.
Note that the :INDICES option in an INDEXED-CLASS either accepts a predefined index or initargs to create a fresh index. It is confusing to mix both initargs and the :INDEX option (which specifies the preexisting index *CLASS-INDEX* to be used). I added code to detect this case. More error checking would certainly be helpful, so please report problems when you encounter them and I'll try to make the code generate better diagnostics.
Please let us know if you have further questions.
Hans