Iterating over a member array with IteratorAggregate

Question

I have a class and I want to be able to iterate over a certain array member. I did a quick search and found IteratorAggregate:

class foo implements IteratorAggregate
{
    protected $_array = array('foo'=>'bar', 'baz'=>'quux');

    public function getIterator()
    {
        return new ArrayIterator($this->_array);
    }
}

which works great, but doesn't that create a new ArrayIterator instance every time foreach is used on it?

So I thought I should store the iterator instance in a member:

    protected $_iterator;

    public function getIterator()
    {
        if (!$this->_iterator instanceof ArrayIterator) {
            $this->_iterator = new ArrayIterator($this->_array);
        }
        return $this->_iterator;
    }

The problem is that the iterator uses a copy of $this->_array during the first call of getIterator(), so changes to the member aren't reflected on subsequent foreach constructs.

I was thinking I should subclass ArrayIterator, add a setArray($array) method and call it before returning it in getIterator(), but I don't know the member name of the array it uses internally and whether or not it's overwriteable by a subclass.

The question is: is this a premature and/or unnecessary optimization? If no, what's the best way to achieve this?

OIS · Accepted Answer · 2008-12-01 17:02:22Z

4

You second code will fail on multiple loops of the object where you start a new loop before another is finished.

Didnt really look like an optimization worth spending time on either.

answered Dec 1, 2008 at 17:02

OIS

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1 Comment

monzee Over a year ago

I see, I haven't considered that possibility.

troelskn · Accepted Answer · 2008-12-01 17:13:31Z

4

but doesn't that create a new ArrayIterator instance every time foreach is used on it?

yes, and?

answered Dec 1, 2008 at 17:13

troelskn

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