public function flag($reason = null)
    {
        $this->props['isValid'] = false;
        $this->classAdd($this->props['attribsContainer'], 'has-error');
        if ($this->attribs['type'] == 'file' && isset($this->form->currentValues[ $this->attribs['name'] ])) {
            $fileInfo = $this->form->currentValues[ $this->attribs['name'] ];
            \unlink($fileInfo['tmp_name']);
            unset($this->form->currentValues[ $this->attribs['name'] ]);
        }
        if (!\is_null($reason)) {
            $this->props['invalidReason'] = $reason;
        }
        return;
    }