public function insert($name, $filter, $default = null, $unique = false, $required = array(), $internal = false)
    {
        //Create the state
        $state = new stdClass();
        $state->name     = $name;
        $state->filter   = $filter;
        $state->value    = null;
        $state->unique   = $unique;
        $state->required = $required;
        $state->default  = $default;
        $state->internal = $internal;
        $this->_data[$name] = $state;

        //Set the value to default
        if(isset($default)) {
            $this->offsetSet($name, $default);
        }

        return $this;
    }