Item::getAccessControllerDefault

static function getAccessControllerDefault()
{
	// prefer to use default access controller
	$cache =& static::getCache();

	if(
		!isset($cache['INSTANCES'])
		|| !is_array($cache['INSTANCES'])
	)
	{
		$cache['INSTANCES'] = array();
	}

	if(!isset($cache['INSTANCES']['AC']))
	{
		$ac = static::getAccessControllerClass();
		/** @var ItemAccess $ac */
		$ac = new $ac();
		$ac->setImmutable(); // once and for all lock this instance in the "immutable" state
		$cache['INSTANCES']['AC'] = $ac;
	}

	return $cache['INSTANCES']['AC'];
}