pop-event

The Pop\Event sub-component is part of the core popphp/popphp component. It serves as the event manager and listener of the event-driven portion of an application written with Pop.

Installation

Install it directly into your project:

composer require popphp/popphp

Or, include it in your composer.json file:

{
    "require": {
        "popphp/popphp": "3.0.*",
    }
}

Basic Use

The event manager provides a way to hook specific event listeners and functionality into certain points in an application’s life cycle. You can create an event manager object and attach, detach or trigger event listeners. You can pass callable strings or already instantiated instances of objects, although the latter could be potentially less efficient.

$events = new Pop\Event\Manager();

$events->on('foo', 'MyApp\Event->bootstrap');
$events->on('bar', 'MyApp\Event::log');

$events->trigger('foo');

The valid callable strings for events are as follows:

  1. ‘SomeClass’
  2. ‘SomeClass->foo’
  3. ‘SomeClass::bar’

With events, you can also inject parameters into them as they are called, so that they may have access to any required elements or values of your application. For example, perhaps you need the events to have access to configuration values from your main application object:

$events->trigger('foo', ['application' => $application]);

In the above example, any event listeners triggered by foo will get the application object injected into them so that the event called can utilize that object and retrieve configuration values from it.

To detach an event listener, you call the off method:

$events->off('foo', 'MyApp\Event->bootstrap');

Event Priority

Event listeners attached to the same event handler can be assigned a priority value to determine the order in which they fire. The higher the priority value, the earlier the event listener will fire.

$events->on('foo', 'MyApp\Event->bootstrap', 100);
$events->on('foo', 'MyApp\Event::log', 10);

In the example above, the bootstrap event listener has the higher priority, so therefore it will fire before the log event listener.