The POD for Encode::Encoding offers this snippet as an example of creating a custom encoding:

package Encode::ROT13;
  use strict;
  use base qw(Encode::Encoding);

  __PACKAGE__->Define('rot13');

  sub encode($$;$){
      my ($obj, $str, $chk) = @_;
      $str =~ tr/A-Za-z/N-ZA-Mn-za-m/;
      $_[1] = '' if $chk; # this is what in-place edit means
      return $str;
  }

  # Jr pna or ynml yvxr guvf;
  *decode = \&encode;

  1;
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Encode provides the following explanation for defining encodings:

To define a new encoding, use:

    use Encode qw(define_encoding);
    define_encoding($object, CANONICAL_NAME [, alias...]);
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CANONICAL_NAME will be associated with $object. The object should provide the interface described in Encode::Encoding. If more than two arguments are provided, additional arguments are considered aliases for $object.

See Encode::Encoding for details.

I seem to be failing to connect the dots. How would one instantiate $object, which in the case of the example code above, I think, should be an instance of the Encode::Rot13 class? What needs to happen before I can "binmode $fh, ':rot13';"?