OlegPy

class Session
{
    public BaseHandler $Interface;
    public function __construct()
    {
        $config = 'BaseHandler';

        if ($config == 'BaseHandler') {
            $this->$Interface = new BaseHandler();
            $Session->$Interface->push('test1', true);
        }
        
        echo 'Session...';
    }
}
$Session = new Session();
if($Session->$Interface) {
    $Session->$Interface->push('test2', true);
}