package Observable;
use strict;

sub new {
  my $class = shift;
  my $self = {};
  $self->{observers} = [];
  $self->{num_observers} = 0;
  bless $self, $class;
}
sub addObserver {
  my $self = shift;
  my $o = shift;
  if ($self->{num_observers} < 500) {
    $self->{observers}->[$self->{num_observers}] = $o;
    $self->{num_observers}++;
  }
}
sub notifyObservers() {
  my $self = shift;
  my $i;
  for ($i=0; $i<$self->{num_observers}; $i++) {
    $self->{observers}->[$i]->update($self);
  }
}
1;