private function check_controller_hash_tmp_file()
	{
	    if(is_writable(dirname($this->controllers_hash_file)))
	    {
	        App :: uses('File', 'Utility');
	        $file = new File($this->controllers_hash_file, true);
	        return $file->exists();
	    }
	    else
	    {
	        $this->Session->setFlash(sprintf(__d('acl', 'the %s directory is not writable'), dirname($this->controllers_hash_file)), 'Risto.flash_error', null, 'plugin_acl');
	        return false;
	    }
	}