But as you can have anonymous hashes and arrays, you can have anonymous subroutines!

Let's add another island inhabitant: Ginger. But rather than define her greeting behavior as a named subroutine, create an anonymous subroutine:

my $ginger = sub {
  my $person = shift;
  print "Ginger: (in a sultry voice) Well hello, $person!\n";
};
$ginger->("Skipper");

An anonymous subroutine looks like:

sub { ... body of subroutine ... }

The value in $ginger is a coderef, just as if you had defined the following block as a subroutine and then taken a reference to it. When you reach the last statement, you see:

Ginger: (in a sultry voice) Well hello, Skipper!

Although you kept the value in a scalar variable, you could have put that sub { ... } construct directly into the initialization of the greetings hash:

my %greets = (

  "Skipper" => sub {
    my $person = shift;
    print "Skipper: Hey there, $person!\n";
  },

  "Gilligan" => sub {
    my $person = shift;
    if ($person eq "Skipper") {
      print "Gilligan: Sir, yes, sir, $person!\n";
    } else {
      print "Gilligan: Hi, $person!\n";
    }
  },

  "Professor" => sub {
    my $person = shift;
    print "Professor: By my calculations, you must be $person!\n";
  },

  "Ginger" => sub {
    my $person = shift;
    print "Ginger: (in a sultry voice) Well hello, $person!\n";
  },

);

my @room; # initially empty
for my $person (qw(Gilligan Skipper Professor Ginger)) {
  print "\n";
  print "$person walks into the room.\n";
  for my $room_person (@room) {
    $greets{$person}->($room_person); # speaks
    $greets{$room_person}->($person); # gets reply
  }
  push @room, $person; # come in, get comfy
}

Notice how much it simplifies the code. The subroutine definitions are right within the only data structure that references them directly. The result is straightforward:

Gilligan walks into the room.

Skipper walks into the room.
Skipper: Hey there, Gilligan!
Gilligan: Sir, yes, sir, Skipper!

Professor walks into the room.
Professor: By my calculations, you must be Gilligan!
Gilligan: Hi, Professor!
Professor: By my calculations, you must be Skipper!
Skipper: Hey there, Professor!

Ginger walks into the room.
Ginger: (in a sultry voice) Well hello, Gilligan!
Gilligan: Hi, Ginger!
Ginger: (in a sultry voice) Well hello, Skipper!
Skipper: Hey there, Ginger!
Ginger: (in a sultry voice) Well hello, Professor!
Professor: By my calculations, you must be Ginger!