In DBDO (my latest phpextension experiment), I wanted to be able to register callback handlers for debug logging, and it would have been nice to use an existing set of tools/API to deal with it. (in the end I copied code from the php-gtk extension)
Regards Alan
Al Baker wrote:
There's nothing stopping someone from writing their own classes for dispatching and handling events and implementing callbacks today...
Are you suggesting something built into PHP like the Java system event queue that people can define their own dispatchers and handlers for? The QT example below is similar, connecting signals to slots instead of dispatching events to listeners.
I guess it makes sense for long running scripts, like PHP-GTK. You probably also want all those events processed in order by the same system component (i.e. the system event queue). However, most web applications have only one "event stimulus" at a time, i.e. the request coming in from the web server. They are then processed and go away in a blink of an eye.
Hey, for PHP-GTK probably want to take it a step further and have some standard event classes (WindowEvent, FocusEvent, etc). Do these already exist? -- haven't looked at PHP-GTK in much detail.
Al
On Tue, 2004-08-31 at 07:53 +0200, BÃrd Farstad wrote:
On Tuesday 31 August 2004 05:46, Alan Knowles wrote:
I think this would be a good idÃa to get into PHP in some way, however I would recommend that the signal/slot technology used in QT should be considered. It's really simple and flexible to use.I've been looking at events in PHP, at present, in PEAR, there are lots of different methods to add callbacks, to packages, for various purposes. It seriously lacks cohesion, and would be nice to sort out at the language level.
Having seen C#, while not perfect, it is an interesting model. There's a very short note on C#, and an idea for a PHP syntax. http://www.akbkhome.com/wiki.php/DBDO/signals.html
It suggests:
class xxxx { // event registers a method, that hooks into the generic event handler. public event $onDebug = array();
function somemethod() {
// add a handler to an event.. // this is the natrual syntax for this, but does open the door to someone wiping the stack! $this->onDebug[] = array($this,'mycallback');
// initiate the signals. (function name matches the var!) $this->onDebug($x,$y); } // a handler.. function mycallback($x,$y) { echo "debug hander got $x , $y\n"; } }
Anyone care to comment on
a) the feasibility
b) the "should it be implemented" question.
c) the "any better ideas" question...
Here is an example of how this could be done in PHP (not the best example, but it should show how it works ):
class MessageHandler { public signal messageSent( $message );
private function checkQueue() { foreach ( $messageQueue as $messsage ) { // Send a signal for each message // So that the connected slots can handle it emit messageSent( $message ); } } }
class MyEmailMessageHandler { public slot sendEmail( $message ) { mail( $message ); } }
class MySMSMessageHandler { public slots sendSMS( $message ) { sendSMS( $message ); } }
When you instantiate your objects:
$messageHandler = new MessageHandler(); $emailHandler = new MyEmailHandler(); $smsHandler = new MySMSHandler();
// Connect is used to connect signals with slots. // A signal can be used by multiple slots and a slot // can have multiple signals connected to it. connect( $messageHandler, 'messageSent', $emailHandler, 'sendEmail' ); connect( $messageHandler, 'messageSent', $emailHandler, 'sendSMS' );
There is some documentation on how that system works here: http://doc.trolltech.com/3.3/signalsandslots.html
It's just an idÃa, but I think OO guys will like this.
--bÃrd
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