title: How can I separate the callback logic in the one single file using codeigniter?
body: <p>I use the config.php to store all the form_validation rules...But I would like to store the callback function in one single file too, how can I do so? Any ideas? Thank you....</p>
  
  <p>Now my file is something like this:</p>
  
  <p>User_controller 
  under user controller have many customized callback_valid , but I ready move all the rules in the config.php. I would like to put the _valid callback to one class. Thank you . </p>