Notepad:PHP Test

<?php

/**
* Event Bus Challenge
* 
* FIRST: COPY/PASTE ALL THIS CODE IN THE TEXTFIELD BELOW AND EDIT IT THERE
* 
* 1. The goal is to build a very simple PubSub/event class in PHP. 
*    We will create an EventEmitter object and then we'll subscribe to events and trigger them. 
*    Subscribing to an event simply adds a callback to be run when the event is triggered. 
*    Triggering an event (emit) should run all the attached callbacks.
* 2. Don't overthink it. The solution should only take a few minutes and a few lines of code. 
*    Build only what you need to get the desired ouput.
* 
* Constraints:
* 1. Although we only use error/success events, please build the class to handle arbitrary events.
* 2. Events data will always be an associative array.
* 3. A callback should always be safe to call.
*/

class EventEmitter {

   var $current_callback;
   
   public function __construct() {
       // no special needs I can see
       $this->current_callback = array();
   }

   public function emit($description , $data) {
       // emit an message using previsouly subscribed function
       // loop through all the previous functions.
       if (!empty($this->current_callback[$description])) {
           foreach ($this->current_callback[$description] as $current) {
               call_user_func($current, $data);
           }
       }
   }

   public function subscribe($description, $callback_func_name) {
       // callback function specified. 
       // add to arrat
       if (empty($this->current_callback[$description])) {
           $this->current_callback[$description] = array();
       }
       $this->current_callback[$description][] = $callback_func_name;
   }

}

$emitter = new EventEmitter;

$error_callback = function($data) {
   echo "Error 1. {$data["message"]} \n";
};

$error_callback2 = function($data) {
   echo "Error 2. {$data["message"]} \n";
};

$success_callback = function($data) {
   echo "SUCCESS! {$data["message"]} \n";
};

$emitter->emit("error", ["message" => "Error one."]);

$emitter->subscribe("error", $error_callback);
$emitter->emit("error", ["message" => "Second error."]);

$emitter->subscribe("error", $error_callback2);
$emitter->emit("error", ["message" => "Yet another error."]);

$emitter->subscribe("success", $success_callback);
$emitter->emit("success", ["message" => "Great success!."]);

// Expected output:

// Error 1. Second error.
// Error 1. Yet another error.
// Error 2. Yet another error.
// SUCCESS! Great success!