I pretty much made this PR to start a discussion.

In this PR:

• Indexed listeners.
• Listeners cannot be added twice. #7 is related.
• Performance of removeListener is significantly improved with a lot of listeners O(N) to Olog(N).

Bug in this PR:

• With once a duplicate listener can be added. (This is fixable).

Do you think this is a common use case and are you willing to support it? If so, we might want to make a different trait, so you can choose whatever case suits your project best.

hi guys,

i have a problem about events in foreach loop... I have this:

$template_events = [
'core_event_head_append'=>'template_event_head_append',
'core_event_after_header'=>'template_event_after_header',
'core_event_before_header'=>'template_event_before_header',
'core_event_after_slider'=>'template_event_after_slider',
'core_event_after_chat'=>'template_event_after_chat',
'core_event_before_left_menu'=>'template_event_before_left_menu',
'core_event_after_left_menu'=>'template_event_after_left_menu',
'core_event_before_right_menu'=>'template_event_before_right_menu',
'core_event_after_right_menu'=>'template_event_after_right_menu',
'core_event_after_news'=>'template_event_after_news',
'core_event_after_comments'=>'template_event_after_comments',
'core_event_before_footer'=>'template_event_before_footer',
'core_event_after_footer'=>'template_event_after_footer',
'core_event_inside_multipurpose_menu'=>'template_event_inside_multipurpose_menu',
'core_event_before_dropbox'=>'template_event_before_dropbox',
'core_event_before_files'=>'template_event_before_files',
'core_event_before_upload_videos'=>'template_event_before_upload_videos',
'core_event_after_contact_description'=>'template_event_after_contact_description',
'core_event_inside_custom_menu'=>'template_event_inside_custom_menu',
'core_event_inside_custom_w_menu'=>'template_event_inside_custom_w_menu',
'core_event_inside_head_ready_front'=>'template_event_inside_head_ready_front',
//admin events
'core_admin_event_ext_pages'=>'template_admin_event_ext_pages',
'core_admin_event_custom_pages_ext'=>'template_admin_event_custom_pages_ext',
'core_admin_event_after_home'=>'template_admin_event_after_home',
'core_admin_event_before_home'=>'template_admin_event_before_home',
'core_admin_event_inside_script_tag'=>'template_admin_event_inside_script_tag',
'core_admin_event_after_jquery'=>'template_admin_event_after_jquery',
'core_admin_event_head_append'=>'template_admin_event_head_append',
];

and try to loop thru all with this:

foreach($template_events as $core_event => $template_event) {
	$dispatcher->on("$core_event", function($data) {
		
	  global $event_dispatcher, $template_event;
	  var_dump($template_event);
	  if(isset($event_dispatcher["$template_event"]))  {
		$event_dispatcher["$template_event"] .= $data;
	  } else {
		$event_dispatcher["$template_event"] = $data;  
	  }
	}); 

}

but i can't... $template_event is not recognizable by on event... it return last value of array..

How to do it properly ?

Event Forwarding

This PR would permit forwarding emitted events between a parent and its children without the need of registering listeners, to the parent, and re-emitting it to the child's listeners. Simply, by passing an object implementing EventEmitterInterface to EventEmitter::forward. Moreover when EventEmitter::emit is called, it will iterate over the children's array and call their emit method with identical arguments.

I ran into a problem where I had to remove a listener for event A in a listener for event B, but in some cases the listener for A was registered with once. Because one-time listeners are wrapped in closures they are not being matched by removeListener.

There are probably myriad ways to solve this, in this PR I tried to minimise changes to on and emit, as well as preserve the current invocation order of the listeners.

What do you think?

I have a use case where i need static calls to the event emitter.

This PR provides a trait which provides all the EventEmitter methods statically.

The solution uses __callStatic to forward calls to an instance of EventEmitter. This prevents any code duplication, since the StaticEventEmitterTrait does not need to be changed when EventEmitter is changed. There is a performance hit, but it's not that bad.

I did some performance testing (https://gist.github.com/ihabunek/8803125). And for 100 listeners, and 100k events, the results are:

Dynamic adding: 0
Dynamic emitting: 4.2352
--
Static adding: 0.001
Static emitting: 4.3292

Also, the performance hit can be mitigated by using:

MyEmitter::emitter()->on(...);

instead of the shorter version which invokes __callStatic:

MyEmitter::on(...);

Hello,

there was a naming conflict in class EventEmitter, listeners was a function and an array, which resulted in the function returning "[" instead of an empty array when no listeners for an event are found.

EventEmitter2 is an implementation of Node's EventEmitter that adds support for namespaced events. It would be handy on PHP as well, and would enable us to make PHP Hook.io implementation together with dnode-php

Node.js EventEmitter has, in addition to on, also an once method.

This method registers a callback, but removes it the first time it has fired. It is quite useful in some situations. See for example the difference between:

https://github.com/bergie/noflo/blob/master/lib/Port.coffee#L35 https://github.com/bergie/phpflo/blob/master/src/PhpFlo/Port.php#L51

Hi guys, i have this:

$event_dispatcher[] = "" //globalize
$dispatcher->on('core_event_after_right_menu', function($data) {
  global $event_dispatcher;
  $event_dispatcher['template_event_after_right_menu'] .= $data;
});

On PHP 7.4 not have any problems, but in 8.1 i get this: PHP Warning: in file C:/xampp2/htdocs/includes/events.php on line 47: Undefined array key "template_event_after_right_menu"

Can you give me a advice how to solve this problem gently ?

PS: The code works, but i get the warning...

https://github.com/igorw/evenement/blob/e5c7014414b4295aae60afa81317015be39e0016/src/Evenement/EventEmitterTrait.php#L51

there logical error

public function off($event, callable $listener = null)
    {
        if ($listener === null) {
            return $this->removeListener($event, $listener);
        }
        return $this->removeAllListeners($event);
}

must be

public function off($event, callable $listener = null)
    {
        if ($listener !== null) {
            return $this->removeListener($event, $listener);
        }
        return $this->removeAllListeners($event);
}

Trying to figure out why PHP doesn't free up memory for evenement @ https://gist.github.com/attozk/e77987fd01488db836b6

I have let the script run for a long time and it still doesn't free up memory. In other cases I have ran out of memory.

Added power support for the travis.yml file with ppc64le. This is part of the Ubuntu distribution for ppc64le. This helps us simplify testing later when distributions are re-building and re-releasing.

Do you plan to make this package compatible with PSR?

https://www.php-fig.org/psr/psr-14 https://github.com/php-fig/event-dispatcher https://github.com/php-fig/event-dispatcher-util

macOS High Sierra 10.13.4 PHP 7.0.31 (cli) (built: Jul 19 2018 23:41:03) ( NTS )

Running this code:

$emitter  = new Evenement\EventEmitter();

$emitter->on('A', function() use (&$emitter) {
  print("Original A call\n");

  $emitter
    ->on('A', function() {
      print("Nested A call\n");
    })
    ->once('A', function() {
      print("Nested A ONCE call\n");
    });
});

$emitter->emit('A');

Produces the following output:

Original A call
Nested A ONCE call

But I think the expected result should be:

Original A call

Something like https://api.jquery.com/event.namespace/ For excample, we want to listen on statusChanged event buy only for value idle. We can code like that:

Listeners:

$this->once("statusChanged.idle", function() {
    echo "The status is changed to idle.\n";
});
$this->on("statusChanged", function() {
   echo "The status is changed.\n";
});

the emitter

$this->emit("statusChange.idle");
$this->emit("statusChange.idle");

Result:

The status is changed to idle
The status is changed.
The status is changed.

instead of

$this->on("statusChanged", function($status) {
   echo "The status is changed.\n";
});
$onceListener = function($status) use (&$onceListener ) {
   if ($status == "idle") {
        echo "The status is changed to idle.\n";
        $this->removeListener("statusChanged", $onceListener);
    }
};
$this->on("statusChanged", $onceListener );
$this->emit("statusChange", ['idle']);

The main advantage that we can easily use it with once.