/ 
Games-Backgammon-0.02
River stage zero No dependents
/ Games::Backgammon

NAME

Games::Backgammon - Perl extension for modelling backgammon games

SYNOPSIS

use Games::Backgammon;

my $game = Games::Backgammon->new(
  position => {
    whitepoints => {3 => 1, 4 => 1, 5 => 3, 6 => 3}, # ideal 40 pip position
    blackpoints => {4 => 3, 5 => 5, 6 => 7},         # ideal 79 pip position
    atroll      => 'black',
  }
);

print "Checkers off from white", $game->whitepoints('off');

## Not implemented yet

$game->manual_roll('6-5');
print "Now you can do these moves: ", join " ", $game->movelist;

$game->move('6-off 5-off');

print join "\n", 
  "Now black has a pip count of " . $game->blackpips,
  "With " . $game->blackpoints('off') . " checkers off the game";

DESCRIPTION

This module helps modelling backgammon games. It is not basically intented to play backgammon for itself. I just wrote it to analyze (long) racings in a convenient way.

FUNCTIONS

my $game = Games::Backgammon->new(position => \%pos)

This creates a new backgammon game. At the moment, it's necessary to define the starting position. The reason is that I just have not yet programmed how to do the beginning roll.

Please look to the documentation of set_position for the definition of the position hash.

$game->set_position(%pos)

Resets the backgammon game to a specific position. You can specify the position of the checkers and who is at the roll. (Of course, in future versions, I'll also add the doubling cube to the position, and the possibility of doubling before a rol).

Thus the position hash has the following outlook:

position => {
   whitepoints => {$point1 => $nr_of_white_checkers_on_point1,
                   $point2 => $nr_of_white_checkers_on_point2,
                   ...
                   'bar'   => $nr_of_white_checkers_on_the_bar},

   blackpoints => {$point1 => $nr_of_black_checkers_on_point1,
                   $point2 => $nr_of_black_checkers_on_point2,
                   ...
                   'bar'   => $nr_of_black_checkers_on_the_bar},
   
   atroll      => 'white'     # or 'black'
}

With the whitepoints and <blackpoints> arguments, you can define where the checkers of each side are. The point numbers are always regarded from the player's view. So point x for white is point (25-x) for black. Please take care that black's and white's checkers are not at the same point (what would result in an error). It's also forbidden that both players have a closed board and both players have checkers on the bar. Specifying more than 15 checkers for a side is allowed, but it gives a warning.

Please also look also to the following example:

 GNU Backgammon  Position ID: sOfgEwDg8+AIBg
 +13-14-15-16-17-18------19-20-21-22-23-24-+     O: gnubg
 | X        X  O    |   | O  O  X          |     0 Points
 | X           O    |   | O  O  X          |     
 | X           O    |   | O                |     
 |                  |   | O                |     
 |                  |   |                  |    
v|                  |BAR|                  |     (Doppler: 1)
 | O                |   | X                |    
 | O           X    |   | X                |     
 | O           X    |   | X                |     
 | O           X    |   | X                |     At Roll
 | O     O     X    |   | X                |     0 Points
 +12-11-10--9--8--7-------6--5--4--3--2--1-+     X: janek
Pip counts: O 138, X 159

This interesting position can be defined with (O is white, X is black)

position => {
    whitepoints => {5 => 2, 6 => 4,  8 => 3, 13 => 5, 15 => 1},
    blackpoints => {6 => 5, 8 => 4, 13 => 3, 16 => 1, 21 => 2},
    atroll      => 'black'
}

The number of checkers at the bar is defined with 'bar' = $nr_of_checkers_at_bar>, while the number of checkers off the game is defined with 'off' = $nr_of_checkers_off>.

The default for the points 1 .. 24 and the bar is 0, while the default for the checkers off the game is max(0,15 - sum(all over points).

The atroll parameter has to be either 'white' or 'black' (whether upper/lower case is unimportant) [the default is 'black'].

This method is unfortunately not explicitly tested (only via the initialization with new).

my %point = $game->whitepoints; my $off = $game->whitepoints('off');

This method returns either the hash with all white points (including the checkers off the game, if there are someones) or the number of checkers at a specific point. The hash is returned when there is no argument specified, while the number of checkers is returned if the point is passed as argument. Note that points without a checker are not represented in the hash.

For further details, please read the documentation of set_position.

my %point = $game->blackpoints; my $off = $game->blackpoints('off');

Similar to whitepoints.

my $atroll = $game->atroll;

Returns the player who is at roll

EXPORT

None by default.

BUGS

Please inform me about every one you can find.

TODO

A lot. I'm working currently on it.

Please feel free to suggest me anything you'll need. (I will do it on the top of my priority list).

SEE ALSO

Have also a look to the great open source project gnubg of Gary Wong.

AUTHOR

Janek Schleicher, <bigj@kamelfreund.de>

COPYRIGHT AND LICENSE

Copyright 2003 by Janek Schleicher

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.