Chess::Piece::Knight - an object representing a knight in a game of chess

Chess documentation Contained in the Chess distribution.

Index

Code Index:

NAME

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Chess::Piece::Knight - an object representing a knight in a game of chess

SYNOPSIS

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    $knight = Chess::Piece::Knight->new("g1", "white", 
                                        "White King's knight");
    $true = $knight->can_reach("f3");
    $true = $knight->can_reach("e2");
    $false = $knight->can_reach("g3");

DESCRIPTION

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

METHODS

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Construction

new()

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

    $knight = Chess::Piece::Knight->new("g1", "white");
    $knight = Chess::Piece::Knight->new("g8", "black", 
                                        "Black King's knight");

Class methods

There are no class methods for this class.

Object methods

reachable_squares()

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.

DIAGNOSTICS

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This subclass of Chess::Piece does not generate any warning messages by itself. Please see DIAGNOSTICS in Chess::Piece or DIAGNOSTICS in Chess::Board for possible error messages your program may produce.

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::Knight;

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

sub new {
    my ($caller, $sq, $color, $desc) = @_;
    my $class = ref($caller) || $caller;
    my $self = $caller->SUPER::new($sq, $color, $desc);
    return bless $self, $class;
}

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

1;