Examples
Examples -- Examples for the usage of Event_Dispatcher
Examples usage of Event_Dispatcher
The following examples show you how to use Event_Dispatcher to
create more flexible applications.
Example 42-1. Basic example
<?php
require_once 'Event/Dispatcher.php';
/**
* Dummy class that simulated authentication
*/
class Auth
{
var $_dispatcher = null;
var $_user;
function Auth(&$dispatcher)
{
$this->_dispatcher = &$dispatcher;
}
function login($username, $password)
{
// Your code that authenticates goes here
// ....
// imagine $this->_user contains a User object
$this->_dispatcher->post($this->_user, 'onLogin');
}
}
function logAuth(&$notification)
{
$user = &$notification->getNotificationObject();
$username = $user->getUsername();
// write logfile
error_log("$username logged in.", 3, '/tmp/auth.log');
}
$dispatcher = &Event_Dispatcher::getInstance();
// catch all onLogin events to write a logfile
$dispatcher->addObserver('logAuth', 'onLogin');
$auth = &new Auth($dispatcher);
// simulate login
$auth->login($_GET['user'], $_GET['pass']);
?>
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In this example, Event_Dispatcher is used to
allow observers to hook into the authentication process. Whenever a
user authenticates, a notification onLogin is
sent.
This can be used to write logfiles or block the application for
other users.
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Example 42-2. Cancelling notifications
<?php
require_once 'Event/Dispatcher.php';
/**
* Dummy class that simulated authentication
*/
class Auth
{
var $_dispatcher = null;
var $_user;
function Auth(&$dispatcher)
{
$this->_dispatcher = &$dispatcher;
}
function login($username, $password)
{
// Your code that authenticates goes here
// ....
// imagine $this->_user contains a User object
$notification = $this->_dispatcher->post($this->_user, 'onLogin');
if ($notification->isNotificationCancelled()) {
echo "You are not allowed to login";
$this->_user->logout();
}
}
}
function logAuth(&$notification)
{
$user = &$notification->getNotificationObject();
$username = $user->getUsername();
// If a special user authenticated, cancel
// the notification
if ($username === 'foo') {
$notification->cancelNotification();
} else {
// write logfile
error_log("$username logged in.", 3, '/tmp/auth.log');
}
}
$dispatcher = &Event_Dispatcher::getInstance();
// catch all onLogin events to write a logfile
$dispatcher->addObserver('logAuth', 'onLogin');
$auth = &new Auth($dispatcher);
// simulate login
$auth->login($_GET['user'], $_GET['pass']);
?>
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In this case, the cancelNotification() method is
used to cancel the notification if a certain user tries to
authenticate.
The login method has been changed as well to check whether the notification
has been cancelled and to take the necessary steps.
This allows you to add some flexible rules to your authentication system.
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