Pepsi Challenge - Memoization

<?php
# flickr.php
  public function photos() {
    return ($this->_photos) ?
      $this->_photos :
      $this->_photos = $this->flickr()->
        groups_pools_getPhotos('1362691@N20', NULL, NULL, NULL, $this->num(), 1);
  }


# flickr.rb
  def photos
    @photos ||= flickr.groups_pools_getPhotos('1362691@N20', NULL, NULL, NULL, num, 1)
  end