public function copyFromBase($instancename, $filename)
{
assert('is_string($instancename)');
assert('is_string($filename)');
assert('$this->filename !== NULL');
// check if we already have loaded the given config - return the existing instance if we have
if (array_key_exists($instancename, self::$instance)) {
return self::$instance[$instancename];
}
$dir = dirname($this->filename);
self::$instance[$instancename] = self::loadFromFile($dir . '/' . $filename, true);
return self::$instance[$instancename];
}