in reply to capturing matching parenthesis

There's also Regexp::Common::balanced. For example: 
use Regexp::Common qw(balanced);
if ($foo =~ / ( $RE{balanced} ) /x) { 
  print "grabbed $1";
}

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If you look at the documentation, you'll see that it can actually be used very flexibly -- it can handle proper nesting of mixed brackets (e.g. () and {}.

Oh, and beware the lowercase 'b' -- took me a few confused tries to install it from CPAN till I noticed that caveat ;)

--Stevie-O 
$"=$,,$_=q>|\p4<6 8p<M/_|<('=>
.q>.<4-KI<l|2$<6%s!<qn#F<>;$,
.=pack'N*',"@{[unpack'C*',$_]
}"for split/</;$_=$,,y[A-Z a-z]
         {}cd;print lc

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In Section Seekers of Perl Wisdom