Regexp code feature

What's the minimum version of Perl needed to reliably exploit the (?{  
code }) feature in regexps?

I'm working on a module that I call Net::IP::Match::Regexp which builds  
and runs regexps that contain simple code blocks.  It works great under  
5.8.1 on my Mac, but I haven't tested older Perl versions yet.

My code turns these IP ranges (randomly generated)
  109.27.190.54/28    => 1
  109.61.26.198/24    => 2
  180.203.154.195/28  => 3
  5.98.198.68/19      => 4
  68.238.145.35/29    => 5

into regexps look like this:

my $re =  
"^(?:0(?:000010101100010110(?{'2'})|1(?:000100111011101001000100100(? 
{'3'})|10110100(?:011011101111100011(?{'5'})|11110100011010(? 
{'4'}))))|1011010011001011100110101100(?{'1'}))";


It's used in this context, pulling the code values out via $^R:

sub match_ip
{
   my ($ip,$re) = @_;

   local $^R;
   use re 'eval';
   unpack("B32", pack("C4", split(/\./, $ip))) =~ /$re/;
   return $^R;
}

Thanks much,
Chris
--
Chris Dolan, Software Developer, Clotho Advanced Media Inc.
608-294-7900, fax 294-7025, 1435 E Main St, Madison WI 53703

Clotho Advanced Media, Inc. - Creators of MediaLandscape Software  
(http://www.media-landscape.com/) and partners in the revolutionary  
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