Chess::Piece::King - an object representation of a king in a game of chess

Chess documentation Contained in the Chess distribution.

Index

Code Index:

NAME

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Chess::Piece::King - an object representation of a king in a game of chess

SYNOPSIS

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    $king = Chess::Piece::King->new("e1", "white", "White King");
    $true = $king->can_reach("d1");
    $true = $king->can_reach("f1");
    $true = $king->can_reach("d2");
    $true = $king->can_reach("e2");
    $true = $king->can_reach("f2");
    $true = $king->can_reach("g1"); # O-O
    $king->set_moved(1);
    $false = $king->can_reach("g1");
    $false = $king->can_reach("d4");
    $king->set_captured(1); # dies with message
    $king->set_checkmated(1); # use this instead
    if ($king->checkmated()) {
	# game over...
    }

DESCRIPTION

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The Chess module provides a framework for writing chess programs with Perl. This class forms part of that framework, representing a bishop in a Chess::Game.

METHODS

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Construction

Constructs a new Chess::Piece::King. Requires two scalar parameters containing the initial square and color of the piece. Optionally takes a third parameter containing a description of the piece.

Class methods

There are no class methods for this class.

Object methods

Overrides base class version. Returns a list of squares that this pawn can reach from its current position. See "reachable_squares()" in Chess::Piece for more details on this method.

Takes no parameters. Returns true if the checkmated flag has been set for this king (as determined by "set_checkmated()".

Takes a single scalar parameter containing a boolean value. Sets the checkmated property of this king to that value.

DIAGNOSTICS

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The program contains a call to Chess::Piece::King::set_captured. This method has been overridden to croak, as the rules don't allow for capturing the king. See "set_checkmated()".

The program contains a reference to a Chess::Piece::King that was not obtained through "new()" or "clone()" in Chess::Piece. Ensure that the program obtains the reference correctly, and that it does not refer to an undefined value.

BUGS

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Please report any bugs to the author.

AUTHOR

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Brian Richardson <bjr@cpan.org>

COPYRIGHT

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Copyright (c) 2002, 2005 Brian Richardson. All rights reserved. This module is Free Software. It may be modified and redistributed under the same terms as Perl itself.

Chess documentation Contained in the Chess distribution. 
package Chess::Piece::King;

use Chess::Board;
use Chess::Piece;
use base 'Chess::Piece';
use Carp;
use strict;

sub captured {
    croak "King can't be captured";
}

sub set_captured {
    croak "King can't be captured";
}

sub reachable_squares {
    my ($self) = @_;
    my $csq = $self->get_current_square();
    my @squares = ( );
    my $sq1 = Chess::Board->square_left_of($csq);
    if (defined($sq1)) {
	push @squares, $sq1;
	my $sq2 = Chess::Board->square_up_from($sq1);
	push @squares, $sq2 if (defined($sq2));
	$sq2 = Chess::Board->square_down_from($sq1);
	push @squares, $sq2 if (defined($sq2));
    }
    $sq1 = Chess::Board->square_right_of($csq);
    if (defined($sq1)) {
	push @squares, $sq1;
	my $sq2 = Chess::Board->square_up_from($sq1);
	push @squares, $sq2 if (defined($sq2));
	$sq2 = Chess::Board->square_down_from($sq1);
	push @squares, $sq2 if (defined($sq2));
    }
    $sq1 = Chess::Board->square_up_from($csq);
    push @squares, $sq1 if (defined($sq1));
    $sq1 = Chess::Board->square_down_from($csq);
    push @squares, $sq1 if (defined($sq1));
    $sq1 = Chess::Board->add_horz_distance($csq, 2);
    push @squares, $sq1 if (defined($sq1) and !$self->moved());
    $sq1 = Chess::Board->add_horz_distance($csq, -2);
    push @squares, $sq1 if (defined($sq1) and !$self->moved());
    return @squares;
}

1;