Subclassing external modules that are not designed for doing so is not a good idea. You could unintentionally give to some of your methods names already used on the base class (now, or in a future release) and break it.

Delegation is a better approach. You can use AUTOLOAD to proxy all the methods unknown to your class to the slave object.

package My::Expect;

use Expect;

sub new {
  my $class = shift;
  my $expect = Expect->new(@_);
  bless { expect => $expect }, $class;
}

sub login { ... }
sub enable { ... }
sub cmd { ... }

sub AUTOLOAD {
    my $method_name = $AUTOLOAD;
    $method_name =~ s/.*:://;

    my $sub = sub { shift->{expect}->$method_name(@_) }
    {
        no strict 'refs';
        *$method_name = $sub;
    }
    goto &$sub;
}
[download]