test.php

<?php

class Foo
{
  public function myMethod()
  {
    $myData = [];
    
    // MyData is filled with approximately 50-500 elements, but with a lot of attributes inside each element.
    // BUT one of the property inside each element is an iterator. Therefore each element looks a bit like this:
    
    /**
     * $myData[] = [
     *  'property1' => 'value1',
     *  // ...,
     *  'property200' => new ArrayIterator()
     * ];
     */
    
    $this->another($myData);
  }
  
  public function another(array $myData)
  {
    // $myData is always iterated and accessed, but never modified. But what happen when the property with the
    // iterator is accessed and itself iterated? Does it trigger a copy of the array?
  }
}