/**
* Allows caller to have the mail subject dynamically set to contain the
* entry counts per-priority level.
*
* Sets the text for use in the subject, with entry counts per-priority
* level appended to the end. Since a Zend_Mail subject can only be set
* once, this method cannot be used if the Zend_Mail object already has a
* subject set.
*
* @param string $subject Subject prepend text.
* @throws \Zend\Log\Exception\RuntimeException
* @return \Zend\Log\Writer\Mail
*/
public function setSubjectPrependText($subject)
{
if ($this->_mail->getSubject()) {
throw new Log\Exception\RuntimeException('subject already set on mail; ' . 'cannot set subject prepend text');
}
$this->_subjectPrependText = (string) $subject;
return $this;
}