Şöyle de bir config.php var:

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.1.6 or newer
 *
 * @package        CodeIgniter
 * @author        ExpressionEngine Dev Team
 * @copyright    Copyright (c) 2008 - 2011, EllisLab, Inc.
 * @license        http://codeigniter.com/user_guide/license.html
 * @link        http://codeigniter.com
 * @since        Version 1.0
 * @filesource
 */

// ------------------------------------------------------------------------

/**
 * CodeIgniter Config Class
 *
 * This class contains functions that enable config files to be managed
 *
 * @package        CodeIgniter
 * @subpackage    Libraries
 * @category    Libraries
 * @author        ExpressionEngine Dev Team
 * @link        http://codeigniter.com/user_guide/libraries/config.html
 */
class CI_Config {

    /**
     * List of all loaded config values
     *
     * @var array
     */
    var $config = array();
    /**
     * List of all loaded config files
     *
     * @var array
     */
    var $is_loaded = array();
    /**
     * List of paths to search when trying to load a config file
     *
     * @var array
     */
    var $_config_paths = array(APPPATH);

    /**
     * Constructor
     *
     * Sets the $config data from the primary config.php file as a class variable
     *
     * @access   public
     * @param   string    the config file name
     * @param   boolean  if configuration values should be loaded into their own section
     * @param   boolean  true if errors should just return false, false if an error message should be displayed
     * @return  boolean  if the file was successfully loaded or not
     */
    function __construct()
    {
        $this->config =& get_config();
        log_message('debug', "Config Class Initialized");

        // Set the base_url automatically if none was provided
        if ($this->config['base_url'] == '')
        {
            if (isset($_SERVER['HTTP_HOST']))
            {
                $base_url = isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) !== 'off' ? 'https' : 'http';
                $base_url .= '://'. $_SERVER['HTTP_HOST'];
                $base_url .= str_replace(basename($_SERVER['SCRIPT_NAME']), '', $_SERVER['SCRIPT_NAME']);
            }

            else
            {
                $base_url = 'http://localhost/';
            }

            $this->set_item('base_url', $base_url);
        }
    }

    // --------------------------------------------------------------------

    /**
     * Load Config File
     *
     * @access    public
     * @param    string    the config file name
     * @param   boolean  if configuration values should be loaded into their own section
     * @param   boolean  true if errors should just return false, false if an error message should be displayed
     * @return    boolean    if the file was loaded correctly
     */
    function load($file = '', $use_sections = FALSE, $fail_gracefully = FALSE)
    {
        $file = ($file == '') ? 'config' : str_replace('.php', '', $file);
        $found = FALSE;
        $loaded = FALSE;

        $check_locations = defined('ENVIRONMENT')
            ? array(ENVIRONMENT.'/'.$file, $file)
            : array($file);

        foreach ($this->_config_paths as $path)
        {
            foreach ($check_locations as $location)
            {
                $file_path = $path.'config/'.$location.'.php';

                if (in_array($file_path, $this->is_loaded, TRUE))
                {
                    $loaded = TRUE;
                    continue 2;
                }

                if (file_exists($file_path))
                {
                    $found = TRUE;
                    break;
                }
            }

            if ($found === FALSE)
            {
                continue;
            }

            include($file_path);

            if ( ! isset($config) OR ! is_array($config))
            {
                if ($fail_gracefully === TRUE)
                {
                    return FALSE;
                }
                show_error('Your '.$file_path.' file does not appear to contain a valid configuration array.');
            }

            if ($use_sections === TRUE)
            {
                if (isset($this->config[$file]))
                {
                    $this->config[$file] = array_merge($this->config[$file], $config);
                }
                else
                {
                    $this->config[$file] = $config;
                }
            }
            else
            {
                $this->config = array_merge($this->config, $config);
            }

            $this->is_loaded[] = $file_path;
            unset($config);

            $loaded = TRUE;
            log_message('debug', 'Config file loaded: '.$file_path);
            break;
        }

        if ($loaded === FALSE)
        {
            if ($fail_gracefully === TRUE)
            {
                return FALSE;
            }
            show_error('The configuration file '.$file.'.php does not exist.');
        }

        return TRUE;
    }

    // --------------------------------------------------------------------

    /**
     * Fetch a config file item
     *
     *
     * @access    public
     * @param    string    the config item name
     * @param    string    the index name
     * @param    bool
     * @return    string
     */
    function item($item, $index = '')
    {
        if ($index == '')
        {
            if ( ! isset($this->config[$item]))
            {
                return FALSE;
            }

            $pref = $this->config[$item];
        }
        else
        {
            if ( ! isset($this->config[$index]))
            {
                return FALSE;
            }

            if ( ! isset($this->config[$index][$item]))
            {
                return FALSE;
            }

            $pref = $this->config[$index][$item];
        }

        return $pref;
    }

    // --------------------------------------------------------------------

    /**
     * Fetch a config file item - adds slash after item (if item is not empty)
     *
     * @access    public
     * @param    string    the config item name
     * @param    bool
     * @return    string
     */
    function slash_item($item)
    {
        if ( ! isset($this->config[$item]))
        {
            return FALSE;
        }
        if( trim($this->config[$item]) == '')
        {
            return '';
        }

        return rtrim($this->config[$item], '/').'/';
    }

    // --------------------------------------------------------------------

    /**
     * Site URL
     * Returns base_url . index_page [. uri_string]
     *
     * @access    public
     * @param    string    the URI string
     * @return    string
     */
    function site_url($uri = '')
    {
        if ($uri == '')
        {
            return $this->slash_item('base_url').$this->item('index_page');
        }

        if ($this->item('enable_query_strings') == FALSE)
        {
            $suffix = ($this->item('url_suffix') == FALSE) ? '' : $this->item('url_suffix');
            return $this->slash_item('base_url').$this->slash_item('index_page').$this->_uri_string($uri).$suffix;
        }
        else
        {
            return $this->slash_item('base_url').$this->item('index_page').'?'.$this->_uri_string($uri);
        }
    }

    // -------------------------------------------------------------

    /**
     * Base URL
     * Returns base_url [. uri_string]
     *
     * @access public
     * @param string $uri
     * @return string
     */
    function base_url($uri = '')
    {
        return $this->slash_item('base_url').ltrim($this->_uri_string($uri), '/');
    }

    // -------------------------------------------------------------

    /**
     * Build URI string for use in Config::site_url() and Config::base_url()
     *
     * @access protected
     * @param  $uri
     * @return string
     */
    protected function _uri_string($uri)
    {
        if ($this->item('enable_query_strings') == FALSE)
        {
            if (is_array($uri))
            {
                $uri = implode('/', $uri);
            }
            $uri = trim($uri, '/');
        }
        else
        {
            if (is_array($uri))
            {
                $i = 0;
                $str = '';
                foreach ($uri as $key => $val)
                {
                    $prefix = ($i == 0) ? '' : '&';
                    $str .= $prefix.$key.'='.$val;
                    $i++;
                }
                $uri = $str;
            }
        }
        return $uri;
    }

    // --------------------------------------------------------------------

    /**
     * System URL
     *
     * @access    public
     * @return    string
     */
    function system_url()
    {
        $x = explode("/", preg_replace("|/*(.+?)/*$|", "\\1", BASEPATH));
        return $this->slash_item('base_url').end($x).'/';
    }

    // --------------------------------------------------------------------

    /**
     * Set a config file item
     *
     * @access    public
     * @param    string    the config item key
     * @param    string    the config item value
     * @return    void
     */
    function set_item($item, $value)
    {
        $this->config[$item] = $value;
    }

    // --------------------------------------------------------------------

    /**
     * Assign to Config
     *
     * This function is called by the front controller (CodeIgniter.php)
     * after the Config class is instantiated.  It permits config items
     * to be assigned or overriden by variables contained in the index.php file
     *
     * @access    private
     * @param    array
     * @return    void
     */
    function _assign_to_config($items = array())
    {
        if (is_array($items))
        {
            foreach ($items as $key => $val)
            {
                $this->set_item($key, $val);
            }
        }
    }
}

// END CI_Config class

/* End of file Config.php */
/* Location: ./system/core/Config.php */