moodle/mod/quiz/accessrule/accessrulebase.php

109 lines
4.4 KiB
PHP

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Base class for rules that restrict the ability to attempt a quiz.
*
* @package mod
* @subpackage quiz
* @copyright 2011 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
defined('MOODLE_INTERNAL') || die();
/**
* A base class that defines the interface for the various quiz access rules.
* Most of the methods are defined in a slightly unnatural way because we either
* want to say that access is allowed, or explain the reason why it is block.
* Therefore instead of is_access_allowed(...) we have prevent_access(...) that
* return false if access is permitted, or a string explanation (which is treated
* as true) if access should be blocked. Slighly unnatural, but acutally the easist
* way to implement this.
*
* @copyright 2009 Tim Hunt
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class quiz_access_rule_base {
protected $_quiz;
protected $_quizobj;
protected $_timenow;
/**
* Create an instance of this rule for a particular quiz.
* @param object $quiz the quiz we will be controlling access to.
*/
public function __construct($quizobj, $timenow) {
$this->_quizobj = $quizobj;
$this->_quiz = $quizobj->get_quiz();
$this->_timenow = $timenow;
}
/**
* Whether or not a user should be allowed to start a new attempt at this quiz now.
* @param int $numattempts the number of previous attempts this user has made.
* @param object $lastattempt information about the user's last completed attempt.
* @return string false if access should be allowed, a message explaining the
* reason if access should be prevented.
*/
public function prevent_new_attempt($numprevattempts, $lastattempt) {
return false;
}
/**
* Whether or not a user should be allowed to start a new attempt at this quiz now.
* @return string false if access should be allowed, a message explaining the
* reason if access should be prevented.
*/
public function prevent_access() {
return false;
}
/**
* Information, such as might be shown on the quiz view page, relating to this restriction.
* There is no obligation to return anything. If it is not appropriate to tell students
* about this rule, then just return ''.
* @return mixed a message, or array of messages, explaining the restriction
* (may be '' if no message is appropriate).
*/
public function description() {
return '';
}
/**
* If this rule can determine that this user will never be allowed another attempt at
* this quiz, then return true. This is used so we can know whether to display a
* final grade on the view page. This will only be called if there is not a currently
* active attempt for this user.
* @param int $numattempts the number of previous attempts this user has made.
* @param object $lastattempt information about the user's last completed attempt.
* @return bool true if this rule means that this user will never be allowed another
* attempt at this quiz.
*/
public function is_finished($numprevattempts, $lastattempt) {
return false;
}
/**
* If, because of this rule, the user has to finish their attempt by a certain time,
* you should override this method to return the amount of time left in seconds.
* @param object $attempt the current attempt
* @param int $timenow the time now. We don't use $this->_timenow, so we can
* give the user a more accurate indication of how much time is left.
* @return mixed false if there is no deadline, of the time left in seconds if there is one.
*/
public function time_left($attempt, $timenow) {
return false;
}
}