Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:43862
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: error (pb1.pair.com: domain smashlabs.com from 67.15.58.61 cause and error)
Received-SPF: none (no valid SPF record)
Message-ID: <4A01A9C3.5010108@smashlabs.com>
Date: Wed, 06 May 2009 10:16:19 -0500
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.9) Gecko/20061207 Thunderbird/1.5.0.9 Mnenhy/0.7.4.666
MIME-Version: 1.0
To: internals <internals@lists.php.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: RecursiveFilterItrator possible issues with inheritance
From: ralph@smashlabs.com (Ralph Schindler)

Hi all,

I'd like to confirm something as a bug and/or design issue.

Currently, its difficult to extend RecursiveFilterIterator() with 
additional __construct() arguments (for configuring its behavior).  The 
reason its difficult is b/c when getChildren() is called, a new instance 
of the RFI is created (only way you'd know this is if you look into the 
source of RFI).

Ideally, this code would work:


$rArray = array('a' => array('ab', 'ac', 'ad' => array('ada', 'adc')), 
'b' => array('bb', 'bc'));

$ri = new RecursiveArrayIterator($rArray);
$filter = new MyRFI($ri, 'argument');
$iterator = new RecursiveIteratorIterator($filter);

foreach ($iterator as $key => $item) {
     echo $key . ' - ' . $item . PHP_EOL;
}

class MyRFI extends RecursiveFilterIterator
{
     protected $_otherArg = null;

     public function __construct($iterator, $otherArg = null)
     {
         $r = new ReflectionClass($this);
         $this->_otherArg = $otherArg;
         parent::__construct($iterator);
     }

     public function accept()
     {
         echo ($this->_otherArg) ? 'Arg Present' : 'Arg NOT Present';
         echo PHP_EOL;
         return true;
     }


The current output would be:


~/tmp/test-rii-filter$ php test-rii-problem.php
Arg Present
Arg NOT Present
0 - ab
Arg NOT Present
1 - ac
Arg NOT Present
Arg NOT Present
0 - ada
Arg NOT Present
1 - adc
Arg Present
Arg NOT Present
0 - bb
Arg NOT Present
1 - bc


The ideal output would be:

Arg Present
Arg Present
0 - ab
Arg Present
1 - ac
Arg Present
Arg Present
0 - ada
Arg Present
1 - adc
Arg Present
Arg Present
0 - bb
Arg Present
1 - bc




The only proposed change I could would be to make the getChildren() 
inside of RecursiveFilterIterator use clone & add a method called 
setIterator() instead of Reflection::newInstance($iterator)

Is this possible? Or is extending and overriding getChildren() the best 
strategy here?

Reason I post is b/c it seems like using clone/setIterator() would 
facilitate better inheritance / better polymorphism.  And since the 
implementation is in the extension, the typical developer would 
generally not understand how getChildren() really works under the hood.

Thanks,
Ralph