Can't get why php unable to parse this code

[hongkildong]

class QuestionTagTable extends Doctrine_Table
{
    public function getRelatedTags(array $tags, $limit = sfConfig::get('app_tags_on_sidebar'))
    {
   
    }
}

PHP reports Parse error: syntax error, unexpected '(', expecting ')' on line 

public function getRelatedTags(array $tags, $limit = sfConfig::get('app_tags_on_sidebar'))

[Barand]

Check out default arguments in the manual

 

 

The default value must be a constant expression, not (for example) a variable, a class member or a function call.

 

http://www.php.net/manual/en/functions.arguments.php#functions.arguments.default