enum.php

<?php

/**
 * Example enum usage.
 *
 * PHP8.1 will introduce the enum keyword, it will negate the need for the of
 * validation code we often see below as enum will "make invalid states
 * unrepresentable"
 *
 * @see https://wiki.php.net/rfc/enumerations
 */

// Old code < PHP8.1
$isValidStatus = function ($status) {
    $allowed = ['draft', 'published', 'archived'];

    if (in_array($status, $allowed)) {
        return true;
    }

    return false;
};

var_dump($isValidStatus('deleted'));

// New code => PHP8.1
enum Status {
    case draft;
    case published;
    case archived;
}

function setStatus(Status $status)
{
    return $status->name;
}

var_dump(setStatus(Status::draft));