https://github.com/brick/event

An event dispatching library for PHP
https://github.com/brick/event

event-dispatcher events php

Last synced: about 1 year ago
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An event dispatching library for PHP

• Host: GitHub
• URL: https://github.com/brick/event
• Owner: brick
• License: mit
• Created: 2014-09-04T09:59:23.000Z (almost 12 years ago)
• Default Branch: master
• Last Pushed: 2024-05-02T23:16:53.000Z (about 2 years ago)
• Last Synced: 2024-09-21T09:52:46.494Z (almost 2 years ago)
• Topics: event-dispatcher, events, php
• Language: PHP
• Homepage:
• Size: 37.1 KB
• Stars: 22
• Watchers: 5
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
Brick\Event

===========



A simple event dispatching mechanism.

[![Build Status](https://github.com/brick/event/workflows/CI/badge.svg)](https://github.com/brick/event/actions)

[![Coverage Status](https://coveralls.io/repos/github/brick/event/badge.svg?branch=master)](https://coveralls.io/github/brick/event?branch=master)

[![Latest Stable Version](https://poser.pugx.org/brick/event/v/stable)](https://packagist.org/packages/brick/event)

[![License](https://img.shields.io/badge/license-MIT-blue.svg)](http://opensource.org/licenses/MIT)

Introduction

------------

This library helps to write extensible software by plugging in external listeners to events dispatched by an application.

Installation

------------

This library is installable via [Composer](https://getcomposer.org/):

```bash

composer require brick/event

```

Requirements

------------

This library requires PHP 7.1 or later.

Overview

--------

This package provides the `EventDispatcher`.

The dispatcher dispatches *events*: an event is a unique `string` along with optional parameters.

The events are intercepted by *listeners*: any `callable` can be an event listener.

### Basic usage

Let's instantiate a dispatcher:

    use Brick\Event\EventDispatcher;

    

    $dispatcher = new EventDispatcher();

And add a few listeners:

    $dispatcher->addListener('startup', function() {

        echo 'Caught startup event';

    });

    

    $dispatcher->addListener('shutdown', function() {

        echo 'Caught shutdown event';

    });

Now, let's dispatch some events:

    $dispatcher->dispatch('startup'); // will display "Caught startup event"

    $dispatcher->dispatch('shutdown'); // will display "Caught shutdown event"

Any additional parameters you pass to `dispatch()` are forwarded to the listeners:

    $dispatcher->addListener('test', function($a, $b) {

        echo "Caught $a and $b";

    });

    $dispatcher->dispatch('test', 'Hello', 'World'); // will display "Caught Hello and World"

### Setting priorities

By default, the listeners are called in the order they have been registered. It is possible to bypass this

natural order by passing a priority to `addListener()`:

    $dispatcher->addListener('startup', function() { ... }, 10);

The default priority is `0`. The listeners with the highest priority will be called first in the chain.

Two listeners with the same priority will be called in the order they have been registered.

### Stopping event propagation

Any listener can decide that the event should not be propagated to further listeners in the chain, by returning `false`:

    $dispatcher->addListener('startup', function() {

        // ...

        return false;

    });

The dispatcher will then break the chain and no further listeners will be called for this event.