private static function _updatePackage($packageName)
	{
		self::_init();
		self::_dispatch('update');
		if (is_null($packageName))
		{
			$package = array();
		}
		elseif (is_string($packageName))
		{
			$package = array($packageName);
		}
		else
		{
			$package = $packageName;
		}
		$installer = self::_getInstaller();
		$installer
			->setUpdate(true)
			->setUpdateWhitelist($package);
		return $installer->run();
	}