c# - 私有(private)成员访问的设计模式？

Question

让我们使用这个简单的例子:

Connect4Board.cs:

public class Connect4Board
{
    private Box[,] _boxes = new Box[7, 6];

    public void DropPieceAt(int column, bool redPiece)
    {
        //Safe modifications to box colors.
    }        

    public Box GetBoxAt(int x, int y)
    {
        return _boxes[x, y];
    }
}

Box.cs :

public class Box
{
    public bool IsRed { get; private set; }
    public bool IsEmpty { get; private set; }
}

我希望 GetBoxAt() 返回一个具有只读属性的框。但是，我希望我的 Connect4Board 能够更改框的颜色。

假设我根本不想使用 internal 修饰符。

我的解决方案(非常难看):

public class Connect4Board
{
    private Box.MutableBox[,] _mutableBoxes = new Box.MutableBox[7, 6];

    public Connect4Board()
    {
        for (int y = 0; y < 6; y++)
        {
            for (int x = 0; x < 7; x++)
            {
                _mutableBoxes[x, y] = new Box.MutableBox();
            }
        }
    }

    public void DropPieceAt(int column, bool isRed)
    {
        //Safe modifications to box colors.
    }        

    public Box GetBoxAt(int x, int y)
    {
        return _mutableBoxes[x, y].Box;
    }
}

public class Box
{
    public bool IsRed { get; private set; }
    public bool IsEmpty { get; private set; }

    private Box()
    {
    }

    public class MutableBox
    {
        public Box Box { get; private set; }

        public MutableBox()
        {
            Box = new Box();
        }

        public void MakeRed() { //I can modify Box here }

        public void MakeYellow() { //I can modify Box here }

        public void MakeEmpty() { //I can modify Box here }
    }
}

有没有什么好的设计模式可以让它更优雅？

Answer 1

您可以使用多种策略。

针对接口(interface)进行编程通常很有用。下面的 IBox 界面不允许人们编辑框(不将其转换为 Box)，但仍然让您的代码保持简单。

public class Connect4Board
{
    private Box[,] _boxes = new Box[7, 6];

    public void DropPieceAt(int column, bool redPiece)
    {
        //Safe modifications to box colors.
    }        

    public IBox GetBoxAt(int x, int y)
    {
        return _boxes[x, y];
    }
}

public interface IBox
{
    bool IsRed { get; }
    bool IsEmpty { get; }
}

public class Box : IBox
{
    public bool IsRed { get; set; }
    public bool IsEmpty { get; set; }
}

另一种方法是使盒子始终不可变(如字符串)，而不是修改盒子的状态，您只需修改数组中哪个盒子位于哪个位置:

public class Connect4Board
{
    private Box[,] _boxes = new Box[7, 6];

    public Connect4Board()
    {
        for(int i = 0; i<7; i++)
        {
            for(int j = 0; j<6; j++)
            {
                // Notice how you're not changing a color, but assigning the location
                _boxes[i,j] = Box.Empty;
            }
        }
    }

    public void DropPieceAt(int column, bool redPiece)
    {
        // Modifications to the top empty location in the given column.
    }        

    public Box GetBoxAt(int x, int y)
    {
        return _boxes[x, y];
    }
}

public class Box
{
    public bool IsRed { get; private set; }
    public bool IsBlack { get; private set; }
    public bool IsEmpty { get; private set; }

    private Box() {}

    public static readonly Box Red = new Box{IsRed = true};
    public static readonly Box Black = new Box{IsBlack = true};
    public static readonly Box Empty = new Box{IsEmpty = true};
}