&__get() issues, again. Major frustration is afoot

Question

Alrighty, I'm getting quite frustrated, namely because I thought I had this issue solved, or had accomplished this successfully before.

Quick preliminary:

• PHP 5.3.6.
• Error reporting cranked to 11. (-1 actually; future safe, all errors/notices)

I have a class, it aggregates request parameters. For giggles here is a stripped down version:

class My_Request{
    private $_data = array();
    public function __construct(Array $params, Array $session){
        $this->_data['params']  = $params;
        $this->_data['session'] = $session;
    }
    public function &__get($key){
        // arrg!
    }
}

Anyways, the reason for arrg! is, no matter what I try, I always get an error whenever the $key doesn't exist. I've tried:

// doesn't work
$null = null;
if(isset($this->_data[$key])){ return $this->_data[$key]; }
return $null;

// doesn't work
return $this->_data[$key];

I've been told ternary operators cannot result in a reference, ergo, that of course doesn't work, but we know that from the if condition attempt anyways. What happens, for example:

// params will have foo => bar, and session hello => world
$myRequest = new My_Request(array('foo' => 'bar'), array('hello' => 'world'));

// throws an error - Undefined index: baz
echo $myRequest->params['baz'];

I'm losing my mind here; perhaps I hallucinated a scenario where I achieved this. Is it not possible to (without throwing a notice) successfully do this?

---

Clarification: Things I've tried

The aforementioned:

// no check, no anything, just try returning : fails
public function &__get($key){
    return $this->_data[$key];
}

// null variable to pass back by reference : fails
public function &__get($key){
    $null = null;
    if(isset($this->_data[$key])){
        return $this->_data[$key];
    }
    return $null;
}

Other attempts:

// can't work - can't return null by reference nor via ternary : fails
public function &__get($key){
    return isset($this->_data[$key])
        ? $this->_data[$key]
        : null;
}

Answer 1

 echo $myRequest->params['baz'];

The isset check in your __get function will look up "params" from $this->_data and return the array. The notice you get is from outside the class and about a key "baz" in the returned array - which in your example was never actually defined.