PEARのHTML_QuickForm　QuickForm.phpのコードなのだが、エラーを吐く
この中の$thisってどういうこと?

function accept(&$renderer)
{
$renderer->startForm($this);
foreach (array_keys($this->_elements) as $key) {
$element =& $this->_elements[$key];
$elementName = $element->getName();
$required = ($this->isElementRequired($elementName) && !$element->isFrozen());
$error = $this->getElementError($elementName);
$element->accept($renderer, $required, $error);
}
$renderer->finishForm($this);
} // end func accept