package IO::Handle;

sub is_chomped { tie *{ $_[0] }, 'Perl6::FH', @_ }
sub is_not_chomped { untie *{ $_[0] } }


package Perl6::FH;

use Tie::Handle;


sub TIEHANDLE {
  my ($class, $real, $sep) = @_;

  ### updated (@_ == 3) -> (@_ > 2)
  return bless [ undef, 1, @_ > 2 ? $sep : () ], "${class}::ARGV"
    if $real == \*ARGV;

  defined fileno($real) or die "$real has no file descriptor!";
  open my($fh), "<&" . fileno($real) or die "can't dup to $real: $!";

  ### updated (@_ == 3) -> (@_ > 2)
  bless [ $fh, @_ == 3 ? $sep : () ], $class;
}


sub READLINE {
  my $self = shift;
  my $fh = $self->[0];
  return if eof $fh;

  local $/ = $self->[1] if @$self == 2;
  my @lines = map { chomp; $_ } wantarray ? <$fh> : scalar <$fh>;
  return wantarray ? @lines : $lines[0];
}


DESTROY { }


AUTOLOAD {
  my $self = shift;
  my $fh = $self->[0];
  (my $meth = $AUTOLOAD) =~ s/.*::/Tie::StdHandle::/;
  $fh->$meth(@_);
}


package Perl6::FH::ARGV;

@ISA = qw( Perl6::FH );


sub READLINE {
  my $self = shift;
  my $fh = $self->[0];

  if (not defined $fh or eof $fh) {
    $self->[1] = 0, push @ARGV, "-" if $self->[1] and not @ARGV;
    $self->[1] = 1, undef($self->[0]), return unless @ARGV;

    my $file = shift @ARGV;
    open $fh, $file or die "Can't open $file: $!";
    $self->[0] = $fh;
  }

  local $/ = $self->[1] if @$self == 3;
  my @lines = map { chomp; $_ } wantarray ? <$fh> : scalar <$fh>;
  return wantarray ? @lines : $lines[0];
}


1;

##</code><code>##

use Perl6::FH;

is_chomped STDIN;
while (<STDIN>) {
  # $_ has already been chomp()ed
  # with whatever $/ is right now
}

##</code><code>##

is_chomped STDIN "";      # paragraph mode
is_chomped STDIN "%%\n";  # fortune mode

##</code><code>##

is_not_chomped STDIN;

##</code><code>##

is_chomped ARGV;

while (<>) {
  # $_ is chomped
}