<?php
class dummy
{
    private $container;
    function __get($var)
    {
        if (isset($this->container[$var])) return $this->container[$var];
        return false;
    }
    function __set($var, $value)
    {
        $this->container[$var]=$value;
    }
}
$a=new dummy;
$a->vars='directly';
echo $a->vars;//direcly
//----------------------------------------
//failed
$a->a['failed']='failed';
echo $a->a['failed'];//return null

//----------------------------------------
//Works!
$a->witharray=array();
$a->witharray['test']='hello';
echo $a->witharray['test'];//hello
?>