public function setContent($content)
    {
        if (!is_null($content) && !is_string($content) && !is_callable(array($content, '__toString')))
        {
            throw new UnexpectedValueException(
                'The view content must be a string or object implementing __toString(), "'.gettype($content).'" given.'
            );
        }

        $this->_content = $content;
        return $this;
    }