[PHP] Re: Qt like Signals and Slots (Idea + Implementation)

[Robert Paul]

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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