NAME

Games::Goban - Board for playing go, renju, othello, etc.

SYNOPSIS

use Games::Goban;
my $board = new Games::Goban ( 
              size => 19,
              game => "go",
              white => "Seigen, Go",
              black => "Minoru, Kitani",
              referee => \&Games::Goban::Rules::Go,
);

$board->move("pd"); $board->move("dd");
print $board->as_sgf;

DESCRIPTION

This is a generic module for handling goban-based board games. Theoretically, it can be used to handle many of the other games which can use Smart Game Format (SGF) but I want to keep it reasonably restricted in order to keep it simple.

METHODS

new(%options);

Creates and initializes a new goban. The options and their legal values (* marks defaults):

size       9, 11, 13, 15, 17, *19 
game       *go, othello, renju, gomoku
white      Any text, default: "Miss White"
black      Any text, default: "Mr Black"
referee    Any subroutine, default: sub {1} # (All moves are valid) 

The referee subroutine takes a board object and a piece object, and determines whether or not the move is legal. It also reports if the game is won.

move

$ok = $board->move($position)

Takes a move, creates a Games::Goban::Piece object, and attempts to place it on the board, subject to the constraints of the referee. If this is not successful, it returns 0 and sets $@ to be an error message explaining why the move could not be made. If successful, updates the board, updates the move number and the turn, and returns true.

get

$move = $board->get($position)

Gets the Games::Goban::Piece object at the given location, if there is one. Locations are specified as per SGF - a 19x19 board starts from aa in the top left corner, with tt in the bottom right. i does not exist.

size

$size = $board->size

Returns the size of the goban.

as_sgf

$sgf = $board->as_sgf;

Returns a representation of the board as an SGF (Smart Game Format) file.

as_text

print $board->as_text(coords => 1)

Returns a printable text picture of the board, similar to that printed by gnugo. Black pieces are represented by X, white pieces by O, and the latest move is bracketed. hoshi points are in their normal position for Go, and printed as an +. Coordinates are not printed by default, but can be enabled as suggested in the synopsis.

register

my $key = $board->register(\&callback);

Register a calllback to be called after every move is made. This is useful for analysis programs which wish to maintain statistics on the board state. The key returned from this can be fed to...

notes

$board->notes($key)->{score} += 5;

notes returns a hash reference which can be used by a callback to store local state about the board.

hash

$hash = $board->hash

Provides a unique hash of the board position. If the phrase "positional superko" means anything to you, you want to use this method. If not, move along, nothing to see here.

Games::Goban::Piece methods

Here are the methods which can be called on a Games::Goban::Piece object, representing a piece on the board.

color

Returns "b" for a black piece and "w" for a white. colour is also provided for Anglophones.

notes

Similar to the notes method on the board class, this provides a private area for callbacks to scribble on.

position

Returns the position of this piece, as a two-character string. Incidentally, try to avoid taking references to Piece objects, since this stops them being destroyed in a timely fashion. Use a position and get if you can get away with it, or take a weak reference if you're worried about the piece going away or being replaced by another one in that position.

move

Returns the move number on which this piece was played.

board

Returns the board object whence this piece came.

SEE ALSO

Smart Game Format: http://www.red-bean.com/sgf/

Games::Go::SGF

The US Go Association: http://www.usgo.org/

AUTHOR

Simon Cozens, simon@cpan.org