Question

I have this class:

class ResultSet 
    implements ArrayAccess, Countable, Iterator {
     /// Rest of implementation ...
}

I’m running into a problem using usort() and passing my object as the first parameter. usort() expects an array instead of an object, but given my implementation of the ArrayAccess interface I don’t know what else it could be needing.

The exact error returned by php is:
Warning: usort() expects parameter 1 to be array, object given.

Answer 1

How would usort know how you’ve implemented ArrayAccess? There is no defined place where the values are kept — that flexibility is the whole point of the interface.

If you are storing the elements in an array that is a private member of the object, you could proxy the usort operation. For example:

public function usort($callback) {
    usort($this->container, $callback);
}