Warning: an "empty" object is NOT considered to be empty
<?php
$var = new stdClass(); // "empty" object
var_dump(empty($var)); // bool(false)
?>
I don't know if there is a standard way to test for "empty" objects, I personally use array casting:
<?php
$var = new stdClass(); // "empty" object
$var = (array) $var; // cast to empty array
var_dump(empty($var)); // bool(true)
?>