# initialize variables

# Loop
  # Display menu and choose item
  # Process menu item:
    # a: add son/father pair
    # d: delete son/father pair
    # e: exit
    # g: get a father
    # o: output hash neatly
    # r: replace a father
    # x: get a grandfather

##</code><code>##

initialize_variables();

my $is_time_to_exit = 0;
while (! $is_time_to_exit) {

  my $choice = choose_menu_item();

  if ($choice eq 'a')    { add_son_father_pair(); }
  elsif ($choice eq 'd') { delete_son_father_pair(); } 
  elsif ($choice eq 'e') { $is_time_to_exit = 1; }
  elsif ($choice eq 'g') { get_a_father(); }
  elsif ($choice eq 'o') { output_hash_neatly(); }
  elsif ($choice eq 'r') { replace_a_father(); }
  elsif ($choice eq 'x') { get_a_grandfather(); }
  else {
   print "Invalid choice, TRY AGAIN!\n";
  }
}
print "Come back again -- goodbye!";

##</code><code>##

sub add_son_father_pair {
  print "Enter a male name: ";
  chomp (my $name1 = lc <STDIN>);

  if (exists $son_father{$name1}) {
     print "Duplicate name -- try again!\n";
     return;
  }

  print "Add a father: ";
  chomp (my $add_dad = lc <STDIN>);
  $son_father{$name1} = $add_dad; 
}

##</code><code>##

# Nothing special about these:
sub add_son_father_pair { die "NYI" }
sub delete_son_father_pair { die "NYI" }
sub get_a_father { die "NYI" }
sub output_hash_neatly { die "NYI" }
sub replace_a_father { die "NYI" }
sub get_a_grandfather { die "NYI" }

# I wanted a bit more detail about this one, though.
sub add_daily_task { die "NYI";
   my ($task_name, $day_of_week, $task) = @_;
   # Dies on error, otherwise returns $time_of_day the task is scheduled for
}

##</code><code>##

$ grep NYI my_perl_script.pl
sub add_son_father_pair { die "NYI" }
sub delete_son_father_pair { die "NYI" }
sub get_a_father { die "NYI" }
sub output_hash_neatly { die "NYI" }
sub replace_a_father { die "NYI" }
sub get_a_grandfather { die "NYI" }
sub add_daily_task { die "NYI";

##</code><code>##

sub add_son_father_pair {
  my $name1 = ask_question("Enter a male name: ");
  if (exists $son_father{$name1}) {
     print "Duplicate name -- try again!\n";
     return;
  }

  my $add_dad = ask_question("Add a father: ");
  $son_father{$name1} = $add_dad;
}

sub ask_question {
   my $question = shift;
   print $question;
   chomp(my $answer = lc <STDIN>);
   return $answer;
}

##</code><code>##

  my $name1 = lc ask_question("Enter a male name: ");

##</code><code>##

sub ask_question {
   my $question = shift;
   print $question;
   chomp(my $answer = lc <STDIN>);
   return $answer;
}

sub ask_for_name {
   my $question = shift;
   return lc ask_question($question);
}

##</code><code>##

sub add_son_father_pair {
  # show the "before" data
  print "add_son_father_pair before\n";
  output_hash_neatly();

  my $name1 = ask_question("Enter a male name: ");
  if (exists $son_father{$name1}) {
     print "Duplicate name -- try again!\n";
     return;
  }

  my $add_dad = ask_question("Add a father: ");
  $son_father{$name1} = $add_dad;

  # Did we do it right?
  print "add_son_father_pair after:\n";
  output_hash_neatly();
}

##</code><code>##

 
$ perl my_perl_script.pl
Undefined subroutine &main::choose_menu_item called at my_perl_script.pl line 7.

##</code><code>##

$ grep TODO my_perl_script.pl
# TODO pull these next few lines into a frobnicate() subroutine
# TODO Can solve world hunger .. but this line is too short to contain the solution
# TODO Try to remember the solution to above TODO!