TYPO3.Flow

Currently references to other objects must be stored in an array or as a single property:

class Invoice {

   /**
    * @var array
    */
   protected $invoiceDetails = array();

   /**
    * @var Customer
    */
   protected $customer;
}

But in many cases it makes sense to store objects in an SPLObjectStorage:

class Blog {

   /**
    * @var \SPLObjectStorage
    */
   protected $posts;
}

By using the SPLObjectStorage we can assure that no post can be added twice
to a blog.

The Persistence Manager should therefore support SPLObjectStorages