# to use attributes of this instances.
fun finalize do end
end
+
+# An object to be finalized only once
+#
+# This is an utility sub-class to `Finalizable` which ensures that `finalized_once`
+# is called only once per instance. User classes implementing `FinalizableOnce`
+# shoud specialize `finalize_once` and _not_ `finalize`. When manipulating the user
+# class, only `finalize` should be called as it protects `finalize_once`.
+class FinalizableOnce
+ super Finalizable
+
+ # Has `self` been finalized? (either by the GC or an explicit call to `finalize`)
+ var finalized = false
+
+ redef fun finalize
+ do
+ if finalized then return
+
+ finalize_once
+ finalized = true
+ end
+
+ # Real finalization method of `FinalizableOnce`, will be called only once
+ #
+ # See: `Finalizable::finalize` for restrictions on finalizer methods.
+ protected fun finalize_once do end
+end