PHP: get namespace from file

/*
 * Is there a better way of determining a file's namespace than stripping it out using file functions?  Reflection doesn't seem to help.
 * --Anatai
 */


/* file.php */
<?php

namespace foo;

// rest of file here

?>


/* index.php */
<?php

$h = fopen('file.php', 'r') or die('wtf');
$n = '';

while (!feof($h) && !$n)
{
    $l = fgets($h);
    if (stripos($l, 'namespace') !== false) $n = preg_replace('/namespace\ +(\w+);/i', '$1', $l);
}

fclose($h);
print $n ? trim($n) : 'Nothing found';

?>