typedef void transformation_change_callback_func (bool non_empty, void *aux);
-struct dataset * create_dataset (transformation_change_callback_func *, void *);
+struct dataset * create_dataset (void);
+
void destroy_dataset (struct dataset *);
void dataset_add_transform_change_callback (struct dataset *,
struct casereader *, struct dictionary *);
bool proc_set_active_file_data (struct dataset *, struct casereader *);
bool proc_has_active_file (const struct dataset *ds);
+struct casereader *proc_extract_active_file_data (struct dataset *);
void proc_discard_output (struct dataset *ds);