When to use a variable variable in PHP?

Question

I\'ve been developing in PHP for a while now, and I still have not had a task where I\'ve had to use variable variables. Can anyone give me examples where using them is a go

Answer 1

I've found a quite good one..

$php = "templates/php/default.php";
$html = "templates/html/default.php";
$css = "templates/css/default.php";
$js = "templates/js/default.php";

now i asked the user to say which file he wants php or/and html..

$userarray = array("php", "css");
foreach($userarray as $file){
    var_dump($$file);
}

output:

templates/php/default.php
templates/css/default.php

I've crossed myself with this when trying to scope static variables self::$file; like this then I remembered I could use variable variables self::$$file; which will be interpreted as self::$php;