'value'=>function($data,$row){
   $id =Yii::app()->user->getId();
   if ($data->id) ==Yii::app()->user->getId())
   return CHtml::link(substr($data->comments, 0, 70)."...",
           Yii::app()-createUrl("controller/comments", array("id"=>$data->message_id)),
           array("controller/ajaxRead", "id"=>$data->id),array("class"=>"ajaxRead"));
   else...blah

substr($data->comments, 0, 70)

Yii::app()-createUrl("controller/comments", array("id"=>$data->message_id))

array("controller/ajaxRead", "id"=>$data->id),array("class"=>"ajaxRead"));