Custom loader library for CodeIgniter to autoload database groups other than $default_group

MY_Loader.php

<?php
class MY_Loader extends CI_Loader {

	public function database($params = '', $return = FALSE, $active_record = NULL)
	{
		parent::database($params, $return, $active_record);

		if ( ! defined('ENVIRONMENT') OR ! file_exists($file_path = APPPATH.'config/'.ENVIRONMENT.'/database.php'))
		{
			if ( ! file_exists($file_path = APPPATH.'config/database.php'))
			{
				show_error('The configuration file database.php does not exist.');
			}
		}

		include($file_path);

		if ( ! isset($db) OR count($db) == 0) return;

		$CI =& get_instance();

		foreach($db as $group_name => $group)
		{
			if($group_name == $active_group) continue;

			$property = 'db_'.$group_name;
			if(property_exists($CI, $property)) continue;

			$CI->$property = &parent::database($group_name);
		}
	}

}