+void *
+var_attach_aux (struct variable *v,
+ void *aux, void (*aux_dtor) (struct variable *))
+{
+ assert (v->aux == NULL);
+ assert (aux != NULL);
+ v->aux = aux;
+ v->aux_dtor = aux_dtor;
+ return aux;
+}
+
+void *
+var_detach_aux (struct variable *v)
+{
+ void *aux = v->aux;
+ assert (aux != NULL);
+ v->aux = NULL;
+ return aux;
+}
+
+void
+var_clear_aux (struct variable *v)
+{
+ assert (v != NULL);
+ if (v->aux != NULL)
+ {
+ if (v->aux_dtor != NULL)
+ v->aux_dtor (v);
+ v->aux = NULL;
+ }
+}
+
+void
+var_dtor_free (struct variable *v)
+{
+ free (v->aux);
+}
+