What will you see as replacement syntax?
It would also be usefull to put a list of argument and define the default argument...

What about a 

'url' => array(

replacement => 
   '<a {href="{title_val%html_quote}"} {title="{title_val%html_quote}"}>{content}</a>',

validation_callback =>
   array('href'=>array('Validator','url')),
arguments=>
   array(
      'href'=>
      array(
        'default_val'=>'{content}',
        'validation'=>array('Validator','url'),
        'forced'=>true
      )
      'title',
      'default'=>'href'
    )
),


If you have a better Idea for declaration, i'm listening, because the current syntax is already quite complex. and my current idea for your suggestion make it even more complex.

But it must be done only one time :)

Oups, done an error on the replacement syntax:

here is the correction:

'replacement' => 
   '<a {href="{href_val%html_quote}"}
{title="{title_val%html_quote}"}>{content}</a>',

I would also like to show my utmost support for this feature.

It would be great if a "BBCODE_TYPE_MULTIARG" flag would allow multiple arguments without them needing to be predefined. The arguments could be passed to callback functions as an array similar to call_user_func_array().

I'm starting development of multi argument, but need testers. Already rewrited some part of code - test passed ok, but need real testing (better under high load), because i'm not very familiar with c =)

Due to this extension not seeing any activity since 2010, this issue will not be fixed. We are therefore closing this now.