<?php 
/**
 * An observable base model.
 *
 * @author Chris Lewis <chris@silentcitizen.com> - 10/13/2006
 */
class AppModel extends Model {
	
	/* Array of observers wanting to be notified when the model is saved. */
	var $beforeSaveL = array();
	
	/**
	 * Override the beforeSave callback and notify our observers.
	 * Remember that if this method doesn't return true, the model will be
	 * tagged as invalid and fail to save.
	 */
	function beforeSave() {
		return $this->notifyObservers();
	}
	
	/**
	 * Dump the observsers (PHP 5).
	 */
	function __destruct() {
		unset($this->beforeSaveL);
	}
	
	/**
	 * Notify our observers.
	 */
	function notifyObservers() {
		$valid = true;
		foreach($this->beforeSaveL as $observer) {
			//Using a flag like this allows the observers to invalidate
			//the model, should they need to. The observers must implement
			//the modelSaving(&$model) method.
			$valid = $valid && $observer->modelSaving($this);
		}
		return $valid;
	}
	
	/**
	 * Register an observer to be notified during beforeSave().
	 * @param $observer The observer.
	 */
	function addObserver(&$observer) {
		array_push($this->beforeSaveL, $observer);
	}
	
}
?>