$bot->$method(\&GetInput, \&ShowOutput);
 # In your main program, you have to define sub GetInput{...}, 
 # and  sub ShowOutput{...}

 # Alternatively, use anonymous subs :
 $bot->$method(sub{print $_[0]; return scalar <>},
               sub{print $_[0] . "\n"});   

##</code><code>##

sub method{
  my ($self, $getInput,$SendOutput) = @_;
 
  my $input = $getInput->("Optional PROMPT parameter, if any\n");
  #.. Do something with $input, and generate $output
  $SendOutput->($output);

}