If a child class has a __construct() function, it won't make
use of its parent's __get() function (and presumably other
overload functions too). Workaround: add a __get() to the child class and call parent::__get($property).

test code:

<?php
class a { function __get() { return 'a::_get'; } }
class b extends a { }
class c extends a { function __construct() { } }
class d extends a { function __construct() { } function __get($p) { return parent::__get($p); } }
$a = new a;
print "a->foo = {$a->foo}\n";
$b = new b;
print "b->foo = {$b->foo}\n";
$c = new c;
print "c->foo = {$c->foo}\n";
$d = new d;
print "d->foo = {$d->foo}\n";
?>

output:

PHP Notice:  Undefined property:  foo in /full/path/overload.php on line 11
overload.php(11) : Notice - Undefined property:  foo
a->foo = a::_get
b->foo = a::_get

Notice: Undefined property:  foo in /full/path/overload.php on line 11
c->foo =
d->foo = a::_get