Posted by Robert Paul on 09/17/05 05:55

For anyone unfamillair with Signals and Slots, have a read:
http://doc.trolltech.com/3.3/signalsandslots.html

It certainly cleared things up for me a bit.

I'll comment in a bit, when they're formulated a bit more clearly...

--Rob

Konrad Kleine wrote:
> Qt like Signals and Slots (Idea + Implementation)
>
> Hey,
>
> I am a big fan of Qt from Trolltech.com and I especially like the signals and slot mechanism. I have implemented a small example in php here.
> It is really not thought of to be production ready, but think about it a little while ;)
>
> You can emit any signal you want with this example unlike to Qt, where
> you have to declarate it in your class.
>
>
> What is done here?
>
> - There is a base class called "PBase".
> - The class "A", "B" and "C" extend the base class "PBase".
> - We create objects of all three classes.
> - Then we connect a signal sent from the A-object to a slot function in the B- and to a completely other slot function in the C-object.
> - When calling the method in the A-object that emits this special signals, the slot function of the B- and C-object are automatically called in arbitary order.
>
>
> What needs to be done?
>
> - You must have the ability to disconnect an object from a signal
> - The way the connections are saved is bad (I think). It should be sufficient to store one reference per object.
>
> Where is the code? Well, here:
>
> <?php
>
> function connect ( $sender_obj, $signal_string, $reciever_obj, $slot_string )
> {
> $sender_obj->connect( $sender_obj, $signal_string, $reciever_obj, $slot_string );
> }
>
> abstract class BaseClass
> {
> private $connection_array;
>
> public function __construct()
> {
> $this->connection_array = array();
> }
>
> public function connect( $sender_obj, $signal_string, $reciever_obj, $slot_string )
> {
> $tmp = array();
>
> $tmp['sender'] = $sender_obj;
> $tmp['signal'] = $signal_string;
> $tmp['reciever']= $reciever_obj;
> $tmp['slot'] = $slot_string;
>
> array_push( $this->connection_array, $tmp );
> }
>
> protected function do_emit_signal()
> {
> $param_count = func_num_args();
> $param_array = func_get_args();
>
> if ( $param_count < 1 )
> {
> trigger_error("the signals name is missing", E_USER_NOTICE);
> }
>
> $param_array = array_slice($param_array, 1, $param_count-1, true);
>
> //$sender_name_string = get_class(); // the name of the class that has connected
> $signal_name_string = func_get_arg(0);
>
> foreach ( $this->connection_array as $key => $con )
> {
> // make sure, we truely talk about the same object (@see === operator)
> if ( $con['sender'] === $this && $con['signal'] == $signal_name_string )
> {
> call_user_func_array(
> array(
> $con['reciever'],
> $con['slot']
> ),
> $param_array
> );
> }
> }
> }
> }
>
> class A extends BaseClass
> {
> public function __construct()
> {
> parent::__construct();
> }
>
> public function do_something()
> {
> // do something here...
> // and then you might want to emit a signal
> $this->do_emit_signal("clicked", "it's me from A");
> }
> }
>
> class B extends BaseClass
> {
> public function __construct()
> {
> parent::__construct();
> }
> public function slot_handle_clicked( $string )
> {
> echo "Hey, I am B and I just caught this value from a signal: <b>" . $string . "</b><br />";
> }
> }
>
> class C extends BaseClass
> {
> public function __construct()
> {
> parent::__construct();
> }
> public function catch_my_signal( $string )
> {
> echo "Hey, I am C and I just caught this value from a signal: <b>" . $string . "</b><br />";
> }
> }
>
>
> $obj_a = new A();
> $obj_b = new B();
> $obj_c = new C();
>
> connect( $obj_a, "clicked", $obj_b, "slot_handle_clicked" );
> connect( $obj_a, "clicked", $obj_c, "catch_my_signal" );
>
> $obj_a->do_something();
> ?>
>
>
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