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Date: Sat, 28 Feb 2004 00:33:18 +0200
To: Adam Maccabee Trachtenberg <adam@trachtenberg.com>,
 internals@lists.php.net
In-Reply-To: <Pine.LNX.4.58.0402271259500.9539@miranda.org>
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Subject: Re: [PHP-DEV] SimpleXML & Casting to String
From: andi@zend.com (Andi Gutmans)
References: <Pine.LNX.4.58.0402271259500.9539@miranda.org>

Basically SimpleXML should know if the property is being fetched for read 
or not (type is passed such as BP_VAR_R or BP_VAR_W). If the case is 
BP_VAR_R (read access) then SimpleXML should return the value and not an 
object.
There might be some places in the engine which aren't covered but it's best 
for the SimpleXML authors to check this out first because in general it 
should work.

At 13:37 27/02/2004 -0500, Adam Maccabee Trachtenberg wrote:
>I know we discussed this already, but after seeing a couple of bug
>reports about SimpleXML, I'm worried our decision only makes sense to
>us and not to regular users. :)
>
>Specifically, since elements and attibutes look like strings, people
>expect them to act like strings. But since they're not objects instead
>of strings, they're completely buffled as how to handle them.
>
>Here are two examples that have come through the bug report system in
>the last day:
>
>$sxe = simplexml_load_string('<root a="123" />');
>if ($sxe['a'] == '123') {
>   // do something
>}
>
>And:
>
>$xml = simplexml_load_string(/* some valid XML string that I'm not
>                                 going to cut and paste here */);
>foreach($xml->user as $user){
>   if (utf8_decode($user->login) == $login &&
>       utf8_decode($user->password) == $password) {
>       // valid users
>   }
>}
>
>Both seem like they should work, but neither do.
>
>In the first example, we're comparing an object with a string. Even
>though $sxe['a']->__toString() == 'a', the comparison fails. (Well, you
>can't actually do that, but you know what I mean.)
>
>In the second example, utf8_decode() expects a string and not an
>object and we again we don't autoconvert.
>
>The problems can be solved by explicitly casting the object to a
>string, but since you rarely need to cast elsewhere in PHP, I don't
>think anyone thinks of it as a necessary step.
>
>Originally, I proposed that PHP autoconvert an object to a string
>whenever the object has a __toString() and it's necessary to treat the
>variable as a string. In the first example, since we're comparing an
>object to a string, we would cast down the object to enable the
>comparison. This would work just like 1 == '1'. In the second case,
>since the function expects a string, we'd also do the cast.
>
>However, Andi (and others) raised some valid issues about edge cases
>and other potential engine problems.
>
>Is there anything we can do to help out people so that SimpleXML works
>as they expect, but doesn't have the potential to unleash hell on PHP
>and the bug system?
>
>Maybe it makes sense to have SimpleXML leaf nodes return as strings
>instead of SimpleXML objects? Or does this merely substitute one set
>of problems for another? (E.g. this breaks iteratation, what happens
>when there's multiple leaves, etc.)
>
>I don't know what the right answer is, but I feel that the current
>solution isn't perfect. It may end up to be the best possible method,
>but I'm not yet convinced it is.
>
>-adam
>
>--
>adam@trachtenberg.com
>author of o'reilly's php cookbook
>avoid the holiday rush, buy your copy today!
>
>--
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