Use simplepie with composer

I am using PHP 7.3.5 and Composer version 1.8.5 and would like to use "simplepie/simplepie": "^1.5" to get data from an rss feed.

When running the below script I get the error: Fatal error: Uncaught Error: Class 'SimplePie\SimplePie' not found

<?php
require 'vendor/autoload.php';

use SimplePie\SimplePie;

$url = 'https://www.reddit.com/r/worldnews/top.rss?t=day';

$feed = new SimplePie();
$feed->set_feed_url($url);
$feed->init();

How to correctly use simplepie with composer?

You can try:

use SimplePie;

This worked in one of my projects.

more complete example (with in composer.json : "simplepie/simplepie": "^1.5"):

use SimplePie;

class RssParser{
    public $url;
    private $feed;
    private $message; // personal class for holding error...

    function __construct($url){

        if (!empty($this->url)) {
            $this->feed = new SimplePie();
            $this->feed->set_feed_url($this->url);
            $this->feed->set_cache_duration(600);

            if ($this->feed->init() === false) {
                $this->message->error('rss-parser NO SimplePie init: ' . $this->feed->error());
            } else {
                $this->feed->handle_content_type();
            }
        } else {
            $this->message->error('rss-parser: no url');
        }
    }

    ...

I'm not a Composer/autoloading specialist, but since Simplepie uses its own autoloader, that may explain this writing.