Object Oriented Design for a Chess game [closed]

Solution 1:

I actually just wrote a full C# implementation of a chess board, pieces, rules, etc. Here's roughly how I modeled it (actual implementation removed since I don't want to take all the fun out of your coding):

public enum PieceType {
    None, Pawn, Knight, Bishop, Rook, Queen, King
}

public enum PieceColor {
    White, Black
}

public struct Piece {
    public PieceType Type { get; set; }
    public PieceColor Color { get; set; }
}

public struct Square {
    public int X { get; set; }
    public int Y { get; set; }

    public static implicit operator Square(string str) {
        // Parses strings like "a1" so you can write "a1" in code instead
        // of new Square(0, 0)
    }
}

public class Board {
    private Piece[,] board;

    public Piece this[Square square] { get; set; }

    public Board Clone() { ... }
}

public class Move {
    public Square From { get; }
    public Square To { get; }
    public Piece PieceMoved { get; }
    public Piece PieceCaptured { get; }
    public PieceType Promotion { get; }
    public string AlgebraicNotation { get; }
}

public class Game {
    public Board Board { get; }
    public IList<Move> Movelist { get; }
    public PieceType Turn { get; set; }
    public Square? DoublePawnPush { get; set; } // Used for tracking valid en passant captures
    public int Halfmoves { get; set; }

    public bool CanWhiteCastleA { get; set; }
    public bool CanWhiteCastleH { get; set; }
    public bool CanBlackCastleA { get; set; }
    public bool CanBlackCastleH { get; set; }
}

public interface IGameRules {
    // ....
}

The basic idea is that Game/Board/etc simply store the state of the game. You can manipulate them to e.g. set up a position, if that's what you want. I have a class that implements my IGameRules interface that is responsible for:

• Determining what moves are valid, including castling and en passant.
• Determining if a specific move is valid.
• Determining when players are in check/checkmate/stalemate.
• Executing moves.

Separating the rules from the game/board classes also means you can implement variants relatively easily. All methods of the rules interface take a Game object which they can inspect to determine which moves are valid.

Note that I do not store player information on Game. I have a separate class Table that is responsible for storing game metadata such as who was playing, when the game took place, etc.

EDIT: Note that the purpose of this answer isn't really to give you template code you can fill out -- my code actually has a bit more information stored on each item, more methods, etc. The purpose is to guide you towards the goal you're trying to achieve.

Solution 2:

Here is my idea, for a fairly basic chess game :

class GameBoard {
 IPiece config[8][8];  

 init {
  createAndPlacePieces("Black");
  createAndPlacePieces("White");
  setTurn("Black");

 }

 createAndPlacePieces(color) {
   //generate pieces using a factory method
   //for e.g. config[1][0] = PieceFactory("Pawn",color);
 }

 setTurn(color) {
   turn = color;
 }

 move(fromPt,toPt) {
  if(getPcAt(fromPt).color == turn) {
    toPtHasOppositeColorPiece = getPcAt(toPt) != null && getPcAt(toPt).color != turn;
    possiblePath = getPcAt(fromPt).generatePossiblePath(fromPt,toPt,toPtHasOppositeColorPiece);
   if(possiblePath != NULL) {
      traversePath();
      changeTurn();
   }
  }
 } 

}

Interface IPiece {
  function generatePossiblePath(fromPt,toPt,toPtHasEnemy);
}

class PawnPiece implements IPiece{
  function generatePossiblePath(fromPt,toPt,toPtHasEnemy) {
    return an array of points if such a path is possible
    else return null;
  }
}

class ElephantPiece implements IPiece {....}