Pingpp\PingppObject::__set PHP Метод

    public function __set($k, $v)
    {
        if ($v === "") {
            throw new InvalidArgumentException('You cannot set \'' . $k . '\'to an empty string. ' . 'We interpret empty strings as NULL in requests. ' . 'You may set obj->' . $k . ' = NULL to delete the property');
        }
        if (self::$nestedUpdatableAttributes->includes($k) && isset($this->{$k}) && is_array($v)) {
            $this->{$k}->replaceWith($v);
        } else {
            // TODO: may want to clear from $_transientValues.  (Won't be user-visible.)
            $this->_values[$k] = $v;
        }
        if (!self::$permanentAttributes->includes($k)) {
            $this->_unsavedValues->add($k);
        }
    }