How to use a variable in: $this->index(); ?

[eluser]chefnelone[/eluser]
Hello.

I'm running this line in a controller:

$this->index(); //it works fine

But I need to use it in this way:

$page = 'index';
$this->$page();// didn't work

or

$page = 'index()';
$this->$page; // didn't work


How can I do this?