- array_map: documentation ( source)
- implode: documentation ( source)
<?php
$e1 = new stdClass();
$e2 = new stdClass();
$e1->test = 'hola';
$e2->test = 'caracola';
$a = array($e1, $e2);
$b = array_map(function($e) { return $e->test; }, $a);
echo implode(', ', $a) . '<br/>';
echo implode(', ', $b) . '<br/>';
?>