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Date: Sun, 12 Aug 2007 15:58:04 -0400
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Subject: Re: [PHP-DEV] Pre-Destructor magic function?
From: info@adaniels.nl (Arnold Daniels)

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Hi Richard,

class A {
  public $bs = array();
  function addB() {
     $this->bs[] = new B($this);
  }
}

class B {
  public $parent;
  function __construct($parent) {
     $this->parent = $parent;
  }
}

function doSomething() {
  $a = new A();
  $a->addB();
  $a->addB();
}

See the problem? The object $a isn't available from global space, but 
because of the circular reference, A and all its Bs won't be picked up 
by the garbage collector. Have this 22 000 times and you run out of memory.

Best regards,
Arnold



Richard Lynch wrote:
> On Fri, August 10, 2007 6:01 pm, Nathanael D. Noblet wrote:
>
> I'm not a PHP OOP expert, so this could be 100% wrong, but...
>
>   
>> $obj = new A(); in a loop the object's never released from memory
>> because of the internal references it holds. __destruct is not called
>> until the end of script execution etc. Now normally in a web request
>>     
>
> If __destruct isn't being called until the end of the script, then PHP
> thinks you still have some way of accessing that object, and it can't
> free it.
>
>   
>> situation this isn't a big deal. However I'm using it in a batch and
>> loop over 22 000 records. Since re-assigning the single object I use
>> isn't freeing any memory it consumes quite a bit.
>>     
>
> Perhaps set some things to NULL or unset them explicitly to convince
> PHP that you are done with them.
>
>   
>> I have gotten around
>> it by creating a special function in the object to manually release
>> the
>> recursive references.
>>     
>
> Well, there you go.
>
> Release the references so PHP knows you are done with them.
>
>   
>> However it would be nice if there were some sort
>> of 'magic' function that could be called on an object so that it knows
>> it is being deleted, sort of like a __preDestruct or something like
>> that... Is that a bad idea? Or I guess better able to handle recursive
>> references in objects would be the other way to solve it I guess.
>>     
>
> __destruct is called right before PHP destroys the object.
>
> There really isn't any event of any significance for a __perDesctruct...
>
> Either you're done with it, or you're not...
>
>   

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