A method for extending CodeIgniter to have pre and post filters simliar to RoR and Cake. The actual method call is left in for reference. This is and addition to the file ./system/core/CodeIgniter.php

pre-and-post-filters.php

<?php //this is a snippet from ./system/core/CodeIgniter.php

/*
 * ------------------------------------------------------
 *  Is there a pre-filter on the requested method?
 * ------------------------------------------------------
 */
   if (isset($CI->pre_filter) && is_array($CI->pre_filter))
	{
		foreach ($CI->pre_filter as $pre_filter_action => $filtered_action)
		{
			if (is_string($filtered_action) && $method == $filtered_action)
			{
				//call pre-filter
				call_user_func_array(array(&$CI,$pre_filter_action),array_slice($URI->rsegments, 2));
			}
			else if (is_array($filtered_action) && in_array($method,$filtered_action))
			{
				//call pre-filter
				call_user_func_array(array(&$CI,$pre_filter_action),array_slice($URI->rsegments, 2));
			}
		}
	}

/*
 * ------------------------------------------------------
 *  Call the requested method
 * ------------------------------------------------------
 */
	//LEAVE THE STANDARD CI METHOD CALL IN HERE
/*
 * ------------------------------------------------------
 *  Is there a post-filter on the requested method?
 * ------------------------------------------------------
 */
 	if (isset($CI->post_filter) && is_array($CI->post_filter))
	{
		foreach ($CI->post_filter as $post_filter_action => $filtered_action)
		{
			if (is_string($filtered_action) && $method == $filtered_action)
			{
				//call post-filter
				call_user_func_array(array(&$CI,$post_filter_action),array_slice($URI->rsegments, 2));
			}
			else if (is_array($filtered_action) && in_array($method,$filtered_action))
			{
				//call post-filter
				call_user_func_array(array(&$CI,$post_filter_action),array_slice($URI->rsegments, 2));
			}
		}
	}