PHP 5 OOP Destructors (yuck)

[garrettroyce]

This code:

<?php
abstract class a {
    public function __construct () {
        echo 'constructing ', __CLASS__, '<br/>';
    }
    public function __destruct() {
        echo 'destructing ', __CLASS__, '<br/>';
    }
}
class b extends a {
    public function __construct() {
        echo 'constructing ', __CLASS__, '<br/>';
        parent::__construct();
    }
    public function __destruct() {
        echo 'destructing ', __CLASS__, '<br/>';
        parent::__destruct();
    }
}
class d {
    public function __construct() {
        echo 'constructing ', __CLASS__, '<br/>';
        $this->b = new b();
    }
    public function __destruct() {
        echo 'destructing ', __CLASS__, '<br/>';
        $this->b->__destruct();
        unset($this->b);
    }
    public $b;
}

new d();
?>

Produces this output:

constructing d
constructing b
constructing a
destructing d
destructing b
destructing a
destructing b
destructing a

The problem being the two last lines of output. The problem is related to d::b. Removing d::b causes everything to destruct correctly, but also completely ruins the functionality of what I'm trying to do :P

It won't hurt my program to have b and a destruct twice, as long as they destruct after d, but I'd like to know why, if possible
Edit:
And for your time, 332 credits to whomever solves it (and some rep)

[xav0989]

when you call the __destruct function, you simply execute the code inside, but you are not actually removing the class. However, when you do the unset, the __destruct code is executed automagically, so no need to be called before, then the object is removed from the memory.

So if not in a context where the object is unloaded, the __destruct function is just a normal function, just a any other function. Remove the

$this->b->__destruct(); 

part, and everything goes on fine.

[garrettroyce]

Nicely done

I was just checking your knowledge, I really didn't spend an hour trying to figure that out ;)

[xav0989]

Anyways, it's always a pleasure to share knowledge, and thanks for the credits

[garrettroyce]

Anyways, it's always a pleasure to share knowledge, and thanks for the credits

Money well spent :P

I think my problem was I spent too much time reading user comments in the PHP documentation. Half of them are wrong so it makes it pretty hard to figure out what's going on.

[xav0989]

I usually don't read it. If I have a question that the doc can't answer I:
* Search google for tutorials, examples or docs
* Search for projects that implement what I am trying to do and inspire myself
* Ask for advice on the forums.

[garrettroyce]

Yeah, I tried to find a good PHP5 OOP tutorial, but I couldn't find anything really worthwhile. It seems like PHP OOP is taking a while for a lot of people to warm up to. I know that there's plenty of really sharp programmers here, so I figured I'd go straight to the experts

[xav0989]

I've always been a fan of OOP, as it permits you to group similar functions under a common context.