构造中对象集的变量在析构函数中超出了作用域

因此，我开始为一个用于学习目的的微框架编写引导脚本（同时学习更多关于编程、php和oop的知识），我遇到了这种奇怪的意外行为。

启动config（）类新对象的变量$config在公共的Bootstrap的__construct中被调用，然后在也是公共的Bootstrap的__destruct中使用。$config的变量本身是公共的，并且在__construct之前声明，如下所示。

现在，奇怪的是，我在__destruct中使用$config时收到了一个通知和致命错误，它说变量不存在，而致命错误是在非对象上调用成员函数（因为$config不存在）

这是剧本，希望有人能指出为什么会发生这种奇怪的行为，我可能错过了什么，这种行为是有道理的，但好吧，我错过了，然后请指出。

<?php
basename($_SERVER["PHP_SELF"]) == "bootstrap.php" ? die("No direct script access allowed") : '';
class Bootstrap
{
		public $config;
		protected $start_route;
		public function __construct()
		{
			$this->settings();
			$config = new Config();
			$this->database();
			$this->routing();
			$start_route = new Route($config);
			$start_route->initiate();
		}
		public function run()
		{
			$db_info = new DatabaseInfo();
			$database = new Database([
				'database_type'    => $db_info->get_db('dbdriver'),
				'database_name'    => $db_info->get_db('database'),
				'server'           => $db_info->get_db('hostname'),
				'username'         => $db_info->get_db('username'),
				'password'         => $db_info->get_db('password'),
				'charset'          => $db_info->get_db('dbcharset'),
				'port'             => $db_info->get_db('port'),
				'prefix'           => $db_info->get_db('dbprefix'),
 
				// driver_option for connection, read more from
				// http://www.php.net/manual/en/pdo.setattribute.php
				'option'           => [
					PDO::ATTR_CASE => PDO::CASE_NATURAL
				]
			]);
			/*
			 *
			 * Read is much faster than Write,
			 * while INSERT will increase load time by ~40ms per each query,
			 * COUNT will only increase by ~2ms
			 *
			 */
			$count = $database->count('site_log', [
				'log_type' => 1
			]);
/*
			$database->insert('site_log', [
				'remote_addr' => '127.0.0.1',
				'request_uri' => '/',
				'log_type'    => 1,
				'message'     => 'Test Query'
			]);
*/
			echo 'The are ' . $count . ' rows in log with severity level of 1!<br />';
		}
		// Since it's being called from __constrcut, it will run before run()
		private function settings()
		{
			require BOOTPATH.'core''config'.CLASSFIX.EXT;
		}
		// Since it's being called from __constrcut, it will run before run()
		private function database()
		{
			require BOOTPATH.'core''database'.CLASSFIX.EXT;
			return;
		}
		// Since it's being called from __constrcut, it will run before run()
		private function routing()
		{
			require BOOTPATH.'core''router'.CLASSFIX.EXT;
			return;
		}
		// Since it's being outputed within __destrcut, it will run after run() and basically last
		public function __destruct()
		{
			$script_end = (float) array_sum( explode( ' ',microtime() ) );
			echo 'Welcome to ' . $config->get_conf('site_name') . '<br />';
			echo 'Processing time: '. sprintf( '%.4f', ( $script_end - APP_START ) ).' seconds';
		}
}