public function createObject($name, $identifier, $data = null)
    {
        if (!isset($this->blueprints[$name])) {
            $this->blueprints[$name] = new FixtureBlueprint($name);
        }
        $blueprint = $this->blueprints[$name];
        $obj = $blueprint->createObject($identifier, $data, $this->fixtures);
        $class = $blueprint->getClass();

        if (!isset($this->fixtures[$class])) {
            $this->fixtures[$class] = array();
        }
        $this->fixtures[$class][$identifier] = $obj->ID;

        return $obj;
    }