gistfile1.php

<?php
class ServiceManager extends ZendServiceManager
{

    public function getSubClasses($class, $directOnly = true)
    {
        $class .= '\\';
        $length = strlen($class);
        $filtered = array();
        $cNames = $this->getCanonicalNames();
        array_walk($cNames, function ($value, $key) use (&$filtered, $class, $directOnly, $length)
        {
            if (substr($key, 0, $length) != $class) {
                return;
            }

            $strrpos = strrpos($key, '\\');
            if (!$directOnly || !$strrpos  || $strrpos <= $length-1) {
                $filtered[$key] = $value;
            }
        });

        return $filtered;
    }
}