**Implement a custom event-driven system in CodeIgniter using hooks and libraries** In this lab topic, we will explore how to implement a custom event-driven system in CodeIgniter using hooks and libraries. This will enable you to create a robust and scalable application architecture, allowing for seamless communication between different components. **What are Hooks in CodeIgniter?** Hooks are a way to extend the core functionality of CodeIgniter by allowing developers to add their own functionality into the application. Hooks are essentially callbacks that are executed at specific points during the execution of the application. They provide a flexible way to integrate third-party libraries or custom code into the application. **What are Libraries in CodeIgniter?** Libraries are reusable components that provide a specific functionality to the application. They can be used to improve performance, flexibility, and maintainability. In this lab topic, we will focus on creating custom libraries to handle events. **Step 1: Create a Custom Library** To implement a custom event-driven system, we first need to create a custom library. Create a new directory in your project with the name `events`. Inside this directory, create a new file called `Event.php`. This file will serve as the entry point for our event library. ```php // events/Event.php defined('BASEPATH') OR die(); class Event { public static function on($event, $arguments = array()) { // Code to be executed when the event is triggered } } ``` **Step 2: Define Events** Events are specific triggers that are used to execute the code in our library. In our example, we will create two events: `on_load` and `on_save`. We define these events using the `Event::$events` array. ```php // events/Event.php (continued) public static function on_load() { // Code to be executed when the application is loaded } public static function on_save() { // Code to be executed when data is saved } ``` **Step 3: Register the Events** To make the events accessible to other parts of the application, we need to register them using the `Event::$register` method. ```php // events/Event.php (continued) Event::$register = array( 'on_load' => 'Event::on_load', 'on_save' => 'Event::on_save' ); ``` **Step 4: Trigger the Events** To trigger an event, we use the `Event::trigger()` method. For example, we can trigger the `on_load` event when a controller action is loaded. ```php // controllers/Controller.php class Controller extends CI_Controller { public function index() { // Trigger the on_load event Event::trigger('on_load'); } } ``` **Step 5: Handle Events in another Part of the Application** To handle events in another part of the application, we create a custom library that listens for events. Create a new directory `events_handlers` and inside it, create a new file called `EventsHandler.php`. ```php // events_handlers/EventsHandler.php defined('BASEPATH') OR die(); class EventsHandler { public static function handle($event, $arguments = array()) { // Code to be executed when the event is triggered } } ``` **Step 6: Register the Events Handler** We need to register the Events Handler library to listen for events. ```php // events_handlers/EventsHandler.php (continued) Event::$handlers = array( 'on_load' => 'EventsHandler::handle', 'on_save' => 'EventsHandler::handle' ); ``` **Conclusion:** In this lab topic, we implemented a custom event-driven system in CodeIgniter using hooks and libraries. We created a custom library and registered events, then triggered these events to execute custom code. We also created a customized listener that handles these events. **Practical Takeaways:** * Use hooks to extend the core functionality of CodeIgniter. * Create custom libraries to encapsulate reusable functionality. * Define and register events in your custom library. * Trigger events to execute custom code. * Create custom handlers to listen for events and execute custom code. **Further Reading:** For more information on hooks, events, and libraries in CodeIgniter, please refer to the official CodeIgniter documentation [here](https://codeigniter.com/user_guide/general/hooks.html). **Poll:** Was this lab topic helpful in understanding how to implement a custom event-driven system in CodeIgniter using hooks and libraries? Please leave a comment with your feedback, or ask for help if you have any questions.