oliverdavies.uk/modules/opd_podcast/src/Guests.php

<?php

declare(strict_types=1);

namespace Drupal\opd_podcast;

/**
 * @implements \IteratorAggregate<Guest>
 */
final class Guests implements \Countable, \IteratorAggregate, \Stringable {

 /**
  * @param Guest[] $guests
  */
  private function __construct(private array $guests) {
  }

  public function count(): int {
    return count($this->guests);
  }

  public function getIterator(): \Traversable {
    return new \ArrayIterator($this->guests);
  }

  public function __toString(): string {
    // TODO: allow for more than two guests.
    if ($this->count() === 2) {
      assert($this->get(0) instanceof Guest);

      return sprintf('%s %s %s', $this->get(0)->getName(), t('and'), $this->get(1)->getName());
    }

    return strval($this->get(0)->getName());
  }

  /**
   * @param Guest[] $guests
   */
  public static function new(array $guests): self {
    return new self($guests);
  }

  private function get(int $offset): ?Guest {
    return $this->guests[$offset];
  }

}