c:\@Work\Perl>perl -wMstrict -le
"sub qre (&;*) {
   my $re = shift->();
   return eval 'qr/$re/xms' . (@_ ? shift : '') or die $@;
   }
 ;;
 my $regex = qre{ join '|', qw/foo bar/ }i;
 print $regex;
"
(?msix:foo|bar)