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Date: Wed, 22 Oct 2008 12:21:24 +0300
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Subject: Re: [PHP-DEV] Destructor Order
From: sv_forums@fmethod.com ("Stan Vassilev | FM")

>> On Wed, Oct 22, 2008 at 5:03 AM, Ryan Panning <rpanning@gmail.com> wrote:
>>> I've been wondering, is such a thing even possible? Is there a good way 
>>> to
>>> implement an object destruct order? Here are my thoughts:
>>>
>>> In the class definition, specify what "level" of destruction the objects
>>> should be on. How, I have no idea, I haven't thought of a good syntax. 
>>> It
>>> should be an integer for what level though.
>>>
>>> Then when the script ends, the engine starts with the highest most level 
>>> of
>>> destruction. It continues down until everything has been destructed. 
>>> With
>>> the last most level being objects with unspecified levels.
>>>
>>> Note: Each level can have more than one class.
>>>
>>> Example destruction order:
>>> 3 = database records (ActiveRecord or such)
>>> 2 = database connection object
>>> 1 = framework objects
>>> 0 = objects with unspecified level
>>


Hi,

This would likely (and possibly rightfully) be frowned upon, but according 
to the current codebase, if the destructor creates a new reference outside 
to the destroyed object while it runs, the object won't be garbage collected 
(a safe call is used that checks for any remaining references after the 
destructor is called).

This allows you to implement destruction priorities yourself easily by using 
a central "DestructManager":

function __destruct()
{
    global $destructManager;

    $this->addObject($this, $priority);
}

function __real_destruct()
{
    ....
}

Those will be collected in the destruction manager and when at shutdown, on 
the manager's own destructor you just need to sort the collection by 
priority and call the "real" destructor.

Now, this will work fine, but has this downside that all objects will be 
held in the memory until script shutdown, so it's naturally not good for 
long running processes.

Regards,
Stan Vassilev