#!/usr/bin/perl
#
# tying knots: how to override a tied filehandle and still access its guts?
use IO::Handle;
use Data::Dumper;

package Hahandle;
use base qw(Tie::Handle);

sub TIEHANDLE {
  my ($class, $ll) = @_; # ll: the "lower level ref"
  return bless {
    _ll => $ll,
    _llwrite => $ll->can('syswrite')
  }, $class;
}

sub WRITE {
  my($self, $buf, $len, $offs) = @_;
  $buf =~ s/(\w+)/$1 $1/g; # quite dirty
  syswrite(STDOUT, $buf, length($buf), $offs);
}

sub llwrite {
  my $self = shift;
  $self->{_llwrite}($self->{_ll}, @_);
}

################

package main;

my $out = IO::Handle->new_from_fd(STDOUT, "w");
$out->write("(0) bong!\n");
my $wr = $out->can('syswrite');
tie(*$out, 'Hahandle', $out);
$out->write("(1) bong!\n");
&$wr($out, "(2) bong!\n");

##</code><code>##

(0) bong!
(1 1) bong bong!
(2 2) bong bong!