$this and php

Little mistake on naming variable make me confuse for almost an hour.

$this

yes, $this is built-in variable that often use in OOP. By using $this, we refer to self referencing variable.

More in php.net manual

<?php
class A
{
function
foo()
{
if (isset(
$this)) {
echo
'$this is defined (';
echo
get_class($this);
echo
")\n";
} else {
echo
"\$this is not defined.\n";
}
}
}

class B
{
function
bar()
{
A::foo();
}
}

$a = new A();
$a->foo();
A::foo();
$b = new B();
$b->bar();
B::bar();
?>