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Date: Wed, 06 Jun 2007 00:20:47 +0200
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To: Antony Dovgal <antony@zend.com>
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Subject: Re: [PHP-DEV] Recursive classes ... possible bug?
From: mark@cyanox.nl ("mark@cyanox.nl")

Antony Dovgal wrote:
> On 06.06.2007 01:10, mark@cyanox.nl wrote:
>> <?php
>> class class1{
>>   public $c2;
>>   function __construct($c2){
>>     $this->c2 = $c2;
>>   }
>> }
>>
>> class class2{
>>   public $c1;
>>   function setC1($c1){
>>     $this->c1 = $c1;
>>   }
>>   function test(){
>>     echo $this == $this->c1->c2?'equals':'not equals'; // Somehow 
>> this if statement triggers the error.
>>   }
>> }
>>
>>
>> $tt = new class2();
>> $t = new class1($tt);
>> $tt->setC1($t);
>> var_dump($t);
>> $tt->test();
>> ?>
>>
>> I get the error:
>>
>> Fatal error: Nesting level too deep - recursive dependency? in 
>> /home/cyanox/DEV/test_object_recursion.php on line 15
>
> $t->$tt->$t->$tt->$t->$tt->$t->$tt->$t->$tt->$t and so on.
> So you get endless recursion when comparing the objects.
>
>> Although it is obvious that there is a recursion I think this simple 
>> example should work without error.
>
> Sure, if you have any proposals/ideas - feel free to share them.
>
Actually theoretically it should not give an error. I just stumbled upon 
this odd behavior when doing something very odd which would not work 
anyway so I can't really think of a situation where the correct behavior 
would be needed. Anyway the following also gives the error.

<?php
class class1{
  public $c2;
  function __construct($c2){
    $this->c2 = $c2;
  }
}

class class2{
  public $c1;
  function test(){
    $this == $this->c1; // no error.
    $this == $this; // errors.
  }
}


$tt = new class2();
$t = new class1($tt);
$tt->c1 = $t;
$tt == $t; // no error.
//$t == $t; // errors.
//$tt == $tt; // errors.
$tt->test(); // errors.
?>