Question

我无法映射这些类：

的订单
托盘
箱

它们形成了一种组合关系，详见this wikipedia article。

班级订单的实例有几个托盘对象，其中包含多个 Box 对象。

这就是我现在所拥有的：

class Order
{
    public Order(){}
    private List<Pallet> _pallets = new List<Pallet>;
    public Pallet Add_pallet()
    {
        Pallet new_pallet = new Pallet(this);
        this._pallets.Add(new_pallet);
        return new_pallet;
    }
    //...other properties and methods...
}

class Pallet
{
    private Order _parent_order;
    private List<Box> _boxes = new List<Box>;
    public Pallet(Order parent_order)
    {
        _parent_order = parent_order;
    }
    public Box Add_Box()
    {
        Box new_box = new Box(this);
        this._boxes.Add(new_box);
        return new_box;
    }
    //...other properties and methods...
}

class Box
{
    private Pallet _parent_pallet;
    public Box(Pallet parent_pallet){}
    //...other properties and methods...
}

所有框必须属于托盘，所有托盘必须属于订单。
如何正确实现这一点以避免这种情况：

static class Program
{
    static void Main()
    {
        Order myOrder = new Order();
        Pallet myPallet = new Pallet(myOrder);
        //Now I have a Pallet that belongs to an Order,
        //but the Order object is not aware of it
    }
}

我应该使用嵌套类还是有些更有用的东西？

Answer 1

我会这样做：

public class Order
{
    private List<Pallet> _pallets = new List<Pallet>;
    internal void Add_pallet(Pallet pallet)
    {
        if (!this._pallets.Contains(pallet))
            this._pallets.Add(pallet);
    }
    //...other properties and methods...
}

public class Pallet
{
    private Order _parent_order;
    private List<Box> _boxes = new List<Box>;
    public Pallet(Order parent_order)
    {
        if (parent_order = null)
            throw ArgumentNilException("parent_order must not be null");
        _parent_order = parent_order;
        _parent_order.Add_pallet(this);
    }
    //...other properties and methods...
}

ASO。

对象组合的实现模式

1 个答案: