php - How can I redirect inside helper class -

in magento, have helper class data

class my_advert_helper_data extends mage_core_helper_abstract { 

where

i have function such

    public function callvalid($arrerror){ ..... 

and in function trying redirect user login...

$this->_redirect($strreturnpath); 

the seturl not redirecting. how can redirect?.. $strreturnpath getting */ path. need go homepage receiving error below

fatal error: call undefined method my_advert_helper_data::_redirect() in  

you can set redirects within helper class following

 mage::app()->getresponse()->setredirect($strreturnpath); 

that should trick.