And how can this be?

Question

PHP

Hello!
once

<?php


namespace app\controllers;


use vendor\core\base\Controller;

class AppController extends Controller
{
    protected static $site = [];

    public function __construct($route)
    {
        parent::__construct($route);
        self::$site['generator'] = 'ВОЙНУШКА';
        self::$site['all_users'] = self::decline(self::pdo('select * from users')->rowCount(), [
            'воин',
            'воина',
            'воинов'
        ]);
        self::$site['page_generation'] = round(microtime(true) - $_SERVER['REQUEST_TIME_FLOAT'], 3) . ' сек, ';
        self::$site['server_time'] = date('H:i:s');
        self::$site['online'] = self::pdo('select * from users where online > ?', [
            time()
        ])->rowCount();
        self::$site['description'] = 'Военная экономическая стратегия';
        $site = self::$site;
        self::set(compact('site'));
    }
}

two

<?php


namespace vendor\core\base;


abstract class Controller extends Model
{
    public $route = [];
    public $vars = [];

    public function __construct($route)
    {
        $this->route = $route;
    }

    public function set($vars)
    {
        $this->vars = $vars;
    }
}

three

Well, how did we call the NON-STATIC set method using self (I just typed it by accident) and the data flew away normally?
Thank you.
ps it will start)))