Directory.php

<?php
class ZendDbSchema_Tool_Project_Context_Migration_Directory
    extends Zend_Tool_Project_Context_Filesystem_Directory
{
    protected $_filesystemName = 'migrations';

    protected $_version;

    public function getName()
    {
        return 'MigrationsDirectory';
    }

    public function init()
    {
        $this->_version = $this->_resource->getAttribute('version');
        parent::init();
        return $this;
    }

    public function getPersistentAttributes()
    {
        return array(
            'version' => $this->getVersion()
        );
    }

    public function setVersion($version)
    {
        $this->_version = $version;
        return $this;
    }

    public function getVersion()
    {
        return $this->_version;
    }
}