[pmwiki-users] Irreproducible behavior - maybe a bug

[Joachim Durchholz]

Patrick R. Michaud wrote:

> On Tue, May 10, 2005 at 11:07:55PM +0200, Joachim Durchholz wrote:
> 
>>I'm despairing over getting a markup to work. Depending on whether 
>>preg_replace was called before or not, Markup() will enter an endless 
>>recursion.
> 
> Doesn't seem like preg_replace (by itself) would be the problem --
> there are quite a few times that preg_replace is called before Markup()
> is called.

Well, it's within config.php, so very little has happened yet.

What bothers me most is that I get a value that when var_dump()ed 
displays as NULL, when (array)ed turns into an array(0, ''), and when 
iterated with foreach turns into array(0, 'mailform2'). Something got 
seriously unhinged within PHP itself.

> In your code...
> 
>>  $text = '';
>>  $size = '';
>>  $attrs = '';
>>  $field = 'To';
>>  $MailForm2[$field . 'Text']
>>    = '<input size="$size" value="$text"$attrs>';
>>  $replacement =
>>    preg_replace(
>>      array('/\\$text/', '/\\$size/', '/\\$attrs/'),
>>      array(htmlentities($MailForm2[$field . 'Text']), $size, $attrs),
>>      $html
>>    );
>>  Markup(
>>    "mailform2-$field",
>>    '>links',
>>    '/\\(:mailform2\\s' . $field . ':\\)/i',
>>    $replacement);
> 
> what is a typical value for $html?  

Ah, one thing that I overlooked.
I'll try again with a less "cobwebby" mind (I was ill yesterday). I'll 
investigate the issue below first though; if that doesn't help, I'll try 
to give a better variable dump.

>>On a tangent: if somebody knows a better way to first define a string as
>>  'bla $var blub'
>>and, later, have $var substituted in it, I'd be grateful. That 
>>preg_replace thing is rather unwieldy anyway. (I have considered eval(), 
>>but it seems to defeat the purpose of precompilation so I'm a bit 
>>cautious about it.)
> 
> Well, there's not a generic good way to do it, which is why I ended up
> creating FmtPageName to do this sort of thing.  But beyond that,
> it's better to use str_replace over preg_replace for straight
> string replacements.

Ah, right. I was looking for str_replace but didn't find it.

> I also wonder about the preg_replace you have above -- given
> 
>>  $MailForm2[$field . 'Text']
>>    = '<input size="$size" value="$text"$attrs>';
>>  $replacement =
>>    preg_replace(
>>      array('/\\$text/', '/\\$size/', '/\\$attrs/'),
>>      array(htmlentities($MailForm2[$field . 'Text']), $size, $attrs),
>>      $html
>>    );
> 
> since '$text' is being replaced by $MailForm2[$field . 'Text'], and
> that value itself contains the string '$text' in it, I wonder if there
> might be some bizarre loop or occurrence there as well.

That's definitely a bug in the code.
And it's entirely conceivable that such a "loopy" replacements throws 
preg_replace() off its track far enough that PHP gets into trouble.

I'll investigate further in that area.

Regards,
Jo