/** Set a language filter for literals.
*
* For example setting setLangFilter('en') will ignore all
* non-english literals.
* Set to null to disable language filtering of literals.
* By default there is no language filter for literals.
*
* @param string $lang The language to accept (for example 'en')
*/
public static function setLangFilter($lang)
{
if (!is_string($lang) and $lang != null) {
throw new InvalidArgumentException("\$lang should be a string or null");
}
self::$_langFilter = $lang;
}
