また、これらの2行:
$subForm = $this->{$spec}
$subForm = $spec;
public function prepareSubForm($spec)
{
if (is_string($spec)) {
$subForm = $this->{$spec};
} elseif ($spec instanceof Zend_Form_SubForm) {
$subForm = $spec;
} else {
throw new Exception('Invalid argument passed to ' .
__FUNCTION__ . '()');
}
$this->setSubFormDecorators($subForm)
->addSubmitButton($subForm)
->addSubFormActions($subForm);
return $subForm;
}