如何在同一个文件中加载类和PHPMailer

I would like to create Trigger which send emails I tried to to add :

use PHPMailer\PHPMailer\PHPMailer;

use PHPMailer\PHPMailer\Exception;

require 'autoload.php';


spl_autoload_register(function ($class_name) {

    $file_name = $class_name . '.php';

    if( file_exists( $file_name ) ) {

        require $file_name;

    }
});

.......

new TriggerDocs();


class TriggerDocs{

$mail = new PHPMailer(true); // not working

}

Fatal error: Class 'PHPMailer' not found in path/Trigger.php

use doesn't include anything. It just imports the specified namespace (or class) to the current scope .