PHP special cases $this->

<?php

class A
{
    public function foo()
    {
        var_dump('FOO');
    }
}

class B
{
    public function foo()
    {
        var_dump('BAR');
    }
    public function destroyTheUniverse()
    {
        $that = null;
        $that =& $this;
        var_dump($that, $this);
        $a = new A();
        $that = $a;
        var_dump($that, $this);
        $this->foo();
        $that->foo();
    }
}

$b = new B();
$b->destroyTheUniverse();

/* Output:

object(B)#1 (0) {
}
object(B)#1 (0) {
}
object(A)#2 (0) {
}
object(A)#2 (0) {
}
string(3) "BAR"
string(3) "FOO"
*/