>    var $vars = {'a'=>'aa', 'b'=>'bb'};

Heh? What does this do and where did you find this snippet?

It should be like this:

var $vars = array{'a'=>'aa', 'b'=>'bb'};

That is incorrect too, where are you seeing this?

OK, now the syntax is correct. This is only example from my code I wrote to demonstrate the confusing with empty()

class A {
   var $vars = array('a'=>'aa', 'b'=>'bb');

function __get ($name) {
    return $this->vars[$name];
}
}
$x = new A();

if (empty($x->a))
    echo "this is empty<br>";
else
    echo "this in not empty<br>";

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.

The __isset() overloading method is called, not __get()

For me it looks like __get() is called. In my experience the only place where this is not working is empty().

class A {
   var $vars = array('a'=>'aa', 'b'=>'bb');

function __get ($name) {
    return $this->vars[$name];
}
}
$x = new A();

if (empty($x->a))
    echo "this is empty<br>";
else
    echo "this in not empty<br>";
echo "x->a::$x->a<br>";

Result is 
this is empty  // This is wrong
x->a::aa   // This is correct

 __isset() is triggered by calling isset() or empty()  on inaccessible members. 

http://no.php.net/manual/en/language.oop5.overloading.php#language.oop5.overloading.members

And soon this will be on the isset(), empty() and unset() pages: http://news.php.net/php.doc.cvs/4114