Undefined variable in __construct()... but I did define it

Question

I've written the following piece of code:

Class stackOverflowExample {

    private $hash;
    private $cookie_file;

    public function __construct(){

        @session_start();

        if(isset($_SESSION['gc_hash'])){
                $this->$hash = $_SESSION['gc_hash'];
        }else{
                $this->$hash = md5(time());
                $_SESSION['gc_hash'] = $this->$hash;
        }

        $this->$cookie_file = "./cookies/{$this->$hash}.txt";

    }

}

But I'm getting this error

Notice: Undefined variable: hash in /var/www/gausie/gc/GeoCaching.Class.php on line 21

Fatal error: Cannot access empty property in /var/www/gausie/gc/GeoCaching.Class.php on line 21

In the original code, line 21 refers to $this->$hash = $_SESSION['gc_hash'];.

I can't see why this is happening, although I'm new to OO PHP. Any ideas?

RiaD · Accepted Answer · 2013-03-04 21:02:48Z

10

just replace $this->$hash by $this->hash

$this->$hash means variable with name equals to variable $hash value

edited Mar 4, 2013 at 21:02

answered Jan 10, 2012 at 14:56

RiaD

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3 Comments

WWW Over a year ago

RiaD's point being that you only require the $ before the this and nowhere else when using PHP's object notation.

bardiir Over a year ago

Correct :) - $this->$hash would reference a variable named like the content of $hash that is placed inside the class. So for it to work you would need to declare $hash = 'hash'; once done that it would work like that too, but that's not really the correct way of doing it. See the answer for how to do that :)

Gausie Over a year ago

Ah. I feel silly. Upvotes. EDIT: I realise this isn't Reddit.

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