Countable

25 Jan 2011 in PHP

Though not strictly part of the Iterator design pattern (and definitely distinct from the Iterator interface of the SPL Library), implementing the Countable interface is complementary functionality.

Partial Listing: /fw/foundation/IWIterator.php

abstract class IWIterator implements Iterator, Countable
{
    protected $array;

    // only method required for the Countable interface
    function count()
    {
        return count($this->array);
    }
    ...
}

Now I can use the count() function on both a PHP array and an IWArray instance. For the example below, I could write count($php_array) and count($iw_array) and both will work as expected.

Pseudo Listing: /adhoc/countable.php

// Retrieve data in the form of an array
$select = new ORMSelect('category');
$categories = ORMFactory::instanceArray('category');  // returns an IWArray object

// The count() function works on the collection
$num_categories = count($categories);