Entry

How does PHP handle arrays of objects?

Jul 8th, 1999 09:57
Eric van der Vlist, Nathan Wallace,

<?
class top {  

    var $top_id;

    function top($id) {
      $this->top_id = $id;
    }

    function test() {
      $this->top_id -= 12;
      return $this->top_id;
    }
}

// You can create the array of objects
$foo   = array();
$foo[] = new top(12);
$foo[] = new top(23);

// But this wouldn't work as expected.
// echo $foo[1]->top_id;

// Neither would this
// echo $foo[0]->test();

// so will this

$tmp = $foo[0];
echo $tmp->test()."\n";

// But keep in mind that a copy has been created and assigned to $tmp.
//
// In this example, the copy has been updated by the test method, 
// not the orginal object ($foo[0]) as can be checked by repeteting 
// the sequence :

$tmp = $foo[0];
echo $tmp->test()."\n";

// If you want to update the original object, you need to reassign it :

$foo[0] = $tmp;

// which may be time and memory consuming for big and complex objects.

// Another solution is to use the ability of PHP to pass arguments
// to function by reference :

function test_top(&$obj){
	return ($obj->test());
}

echo test_top(&$foo[0])."\n";
echo test_top(&$foo[0])."\n";
echo test_top(&$foo[0])."\n";

// is not very OO but will do the trick.

?>

PHP objects are best dealt with using a "Keep It Simple" philosophy...