opensourcepos/app/Config/Events.php

<?php

namespace Config;

use CodeIgniter\Events\Events;
use CodeIgniter\Exceptions\FrameworkException;
use Exception;
use Dotenv\Dotenv;

/*
 * --------------------------------------------------------------------
 * Application Events
 * --------------------------------------------------------------------
 * Events allow you to tap into the execution of the program without
 * modifying or extending core files. This file provides a central
 * location to define your events, though they can always be added
 * at run-time, also, if needed.
 *
 * You create code that can execute by subscribing to events with
 * the 'on()' method. This accepts any form of callable, including
 * Closures, that will be executed when the event is triggered.
 *
 * Example:
 *      Events::on('create', [$myInstance, 'myMethod']);
 */

Events::on('pre_system', function ()
{
	if (ENVIRONMENT !== 'testing')
	{
		if (ini_get('zlib.output_compression'))
		{
			throw FrameworkException::forEnabledZlibOutputCompression();
		}

		while (ob_get_level() > 0)
		{
			ob_end_flush();
		}

		ob_start(static function ($buffer) { return $buffer; });

		try
		{
			$config_path = APPPATH . 'config/config.php';
			$dotenv = new Dotenv($config_path);
			$dotenv->overload();
		}
		catch (Exception $e)
		{
			// continue, .env file not present
		}
	}

	/*
	 * --------------------------------------------------------------------
	 * Debug Toolbar Listeners.
	 * --------------------------------------------------------------------
	 * If you delete, they will no longer be collected.
	 */
	if (CI_DEBUG && !is_cli())
	{
		Events::on('DBQuery', 'CodeIgniter\Debug\Toolbar\Collectors\Database::collect');
		Services::toolbar()->respond();
	}
});

Events::on('post_controller_constructor', ['Load_config', 'load_config']);	//TODO: This fails. Load_config not found

Events::on('post_controller', ['Db_log', 'db_log_queries']);

Events::on('pre_controller', ['Method', 'validate_method']);