Description:
------------
Using variable variables ($$MyVar) in classes, through functions that is, doesn't allow $this to be used.

I tried with $this (notice the $) too, no difference.
A workaround is to check the object name, if it's "this" you could $this->$Mem instead.

Reproduce code:
---------------
<?php
class Foo {
    public $MyVal = "Test";

    public Bar($Obj, $Mem) {
        return ${$Obj}->$Mem;
    }
}

$TheObject = new Foo();
$Objname = "this";
$Memname = "MyVal";
echo $TheObject->Bar($Objname, $Memname);
?>

Expected result:
----------------
I expect it to output "Test"

Actual result:
--------------
Notice: Undefined variable: this in (filepath) on line 6
Notice: Trying to get property of non-object in (filepath) on line 6