Codeigniter：语言文件中的变量/配置项

我有一个语言文件，其中包含一长串用于我的视图文件的字符串。 我的问题是如何将变量或配置项传递到语言文件？

<?php $lang['error_activation_key_expired'] = 'The activation key you have attempted using has expired. Please request a new Activation Key <a href="'.$this->config->item('base_url').'member/request_activation" title="Request a New Activation Key">here</a>.';

我可以满足于

<?php $lang['error_activation_key_expired'] = 'The activation key you have attempted using has expired. Please request a new Activation Key <a href="'.$base_url.'member/request_activation" title="Request a New Activation Key">here</a>.';

并以某种方式将 base_url 传递给它。我只是不知道怎么办。

Thanks!

在CI论坛上，恩洛乔夫 http://codeigniter.com/forums/viewthread/145634/#745143建议更好的解决方案。
它可以切换变量顺序。

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class MY_Language extends CI_Language
{

    function MY_Language()
    {
        parent::CI_Language();
    }

    /**
     * Fetch a single line of text from the language array. Takes variable number
     * of arguments and supports wildcards in the form of '%1', '%2', etc.
     * Overloaded function.
     *
     * @access public
     * @return mixed false if not found or the language string
     */
    public function line()
    {
        //get the arguments passed to the function
        $args = func_get_args();

        //count the number of arguments
        $c = count($args);

        //if one or more arguments, perform the necessary processing
        if ($c)
        {
            //first argument should be the actual language line key
            //so remove it from the array (pop from front)
            $line = array_shift($args);

            //check to make sure the key is valid and load the line
            $line = ($line == '' OR ! isset($this->language[$line])) ? FALSE : $this->language[$line];

            //if the line exists and more function arguments remain
            //perform wildcard replacements
            if ($line && $args)
            {
                $i = 1;
                foreach ($args as $arg)
                {
                    $line = preg_replace('/\%'.$i.'/', $arg, $line);
                    $i++;
                }
            }
        }
        else
        {
            //if no arguments given, no language line available
            $line = false;
        }

        return $line;
    }


}

?> 

使用案例~

//in english
$lang['some_key'] = 'Some string with %1 %2.';

//in another language
$lang['some_key'] = 'Some string %2 with %1.';

//the actual usage
echo $this->lang->line('some_key','first','second');