If it does, write it, and return true. If not, add it to the references array. Depending on whether or not the spl_object_hash function can be used ( available (PHP >= 5.2), and can only be used on an object) things are handled a bit differently: - if possible, objects are hashed and the hash is used as a key to the references array. So the array has the structure hash => reference - if not, the object is pushed to the references array, and array_search is used. So the array has the structure reference => object. maxing out the number of stored references improves performance(tested with an array of 9000 identical objects). This may be because isset's performance is linked to the size of the array. weird... note on using $references[$count] = &$obj; rather than $references[] = &$obj; the first one is right, the second is not, as with the second one we could end up with the following: some object hash => 0, 0 => array. (it should be 1 => array)

This also means that 2 completely separate instances of a class but with the same values will be written fully twice if we can't use the hash system