Originally I came up with the same basic solution as Joost thinking that the forward references would be a problem, however I still thought it would be nice to have direct access to the objects without an intervening global hash. So I came up the following madness that creates a new singleton class for each room on the fly in the same manner as Re: Creating packages on the fly (and thus comes with all the same caveats). The advantage of using a singleton class is that the problem with the forward references goes away, you just call the constructor whenever you need to and you will either get a new object or get the same one if the constructor had already been called. Obviously creating individual classes for the rooms might not be considered the best design choice by OO purists but that is necessary here for the singleton thing to work. 

use strict;
use warnings;
 
my $world = World->new();
my $current = $world->start();
print $current->describe_room();
 
$current = $current->exit("north");
print $current->describe_room();
 
package World;
 
sub new
{
   my ($class) = @_;
 
   my $self = bless {}, $class;
 
 
   while(<main::DATA>)
   {
     chomp;
     my ($room_name,$start,$north,$south,$east,$west) = split /,/;
 
     my $room = $room_name->instance();
     $room->add_exit("north",$north->instance()) if $north;
     $room->add_exit("south",$south->instance()) if $south;
     $room->add_exit("east",$east->instance()) if $east;
     $room->add_exit("west",$west->instance()) if $west;
     $room->description($room_name);
     $self->start($room) if $start;
   }
 
   return $self;
}
 
 
sub start
{
    my ($self, $start ) = @_;
 
    if ( defined $start )
    {
       $self->{_start_room} = $start;
    }
 
    return $self->{_start_room};
}
 
package Room;
 
use base qw(Class::Singleton);
 
my @exits = qw(north south east west);
 
sub add_exit
{
   my ( $self,$direction, $room ) = @_;
 
   $self->{_exits}->{$direction} = $room;
}
 
sub exit
{
   my ($self, $direction ) = @_;
 
   return exists $self->{_exits}->{$direction} ?
                 $self->{_exits}->{$direction} : undef;
}
 
sub exits
{
   my ($self) = @_;
 
   return keys %{$self->{_exits}};
}
 
sub describe_room
{
    my ($self) = @_;
 
    my $description = "You are in the " . $self->description() ."\n";
    $description .= "There are exits:\n";
    foreach my $exit ( $self->exits() )
    {
      $description .= "To the $exit going to the "
                      . $self->exit($exit)->description() . "\n";
    }
 
    return $description;
}
 
sub description
{
   my ( $self, $description ) = @_;
 
   if (defined $description)
   {
      $self->{_description} = $description;
   }
   return $self->{_description};
}
 
sub DESTROY {}
 
package UNIVERSAL;
 
sub DESTROY {}
 
sub AUTOLOAD
{
   my ($class, @args) = @_;
 
   our $AUTOLOAD;
 
   (my $method = $AUTOLOAD) =~ s/.*:://;
 
 
 
   no strict 'refs';
 
   push @{"${class}::ISA"},'Room' ;
 
   $class->$method( @args);
}
 
package main;
 
__END__
Hall,1,Store,,,
Store,0,,Hall,Cupboard,Corridor
Cupboard,0,,,,Store
Corridor,0,,,Store,

[download]
Obviously that is the bare bones to demonstrate that the scheme works, and quite honestly I wouldn't recommend it to anyone of faint heart, but it's another way of doing it.

/J\

In reply to Re: Building a room system for an adventure game by gellyfish
in thread Building a room system for an adventure game by yoda54

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