Include once ob_get_contents undefined variables

Question

In my admin.php I set my $controller and it works great as a dynamic CMS, the problem I have is the files that I am using as templates don't recognize $controller in them.

Admin.php

include_once("configuration.php");
require("cms.php");
$controller = new CMS();
...
$controller->template("body");

Cms.php

Class CMS{
   /*New template function*/
   function template($file){
      if( isset($file) && file_exists($file.".php") ){
         include_once($file.".php");
      }else{
         echo "";
      }
    }

  /*Old template function*/
  function template($file){
     if(isset($file) && file_exists($file.".php")){
        ob_start();
        include($file.".php");
        $template = ob_get_contents();
        return $template;
       } else {
         echo "";
       }
   }

}

Any template page

var_dump($controller);

Which echos Notice: Undefined variable: controller in

It'll be easier if I can get $controller to be accessible without having to call it every time. Am I missing something here why is the $controller undefined on any template page?

UPDATE

What seemed to work for me is by adding the var again like so

Class CMS{
   /*New template function*/
   function template($file){
      if( isset($file) && file_exists($file.".php") ){
         $controller = $this;
         include_once($file.".php");
      }else{
         echo "";
      }
    }
}

is that acceptable?