Package::setIndex

protected function setIndex($index)
{
	if (!is_string($index))
		throw new ArgumentNullException("packageIndex");
	if (!preg_match("/^pIndex([0-9]+)$/", $index))
		throw new ArgumentException("Index must be a string like '^pIndex([0-9]+)$'", "packageIndex");

	$this->index = $index;
}