限制通用子类方法可以在C#中接受的类型 [英] Restrict types a generic subclass method can accept in c#

问题描述

如果标题不明确或重复，我深表歉意.今天，我花了大量的时间在泛型上阅读并寻找类似的情况，但无济于事.

I apologise if the title is ambiguous or if this is a duplicate. I've spent today reading a ton on generics and looking for a similar situation to no avail.

我正在编写一个小游戏引擎.这方面的一个方面是单位"携带资源的能力.有些单位可以携带任何资源，有些单位只能携带某些专门资源.为此，我具有以下结构:

I'm writing a little game engine. One aspect of this is the ability for a 'unit' to carry resources. Some units can carry any resource, some are restricted to carrying certain specialised resources. To this end I have the following structure:

Resource基类:

public abstract class Resource
{
    private int _count;

    public int Count
    {
        get { return _count; }
        set { _count = value; }
    }

    public Resource(int resourceCount)
    {
        _count = resourceCount;
    }
}

然后是Resource专业化Wood:

public class Wood : Resource
{
    public Wood(int resourceCount) : base(resourceCount)
    {
    }
}

然后我有了通用的ResourceStore:

public class ResourceStore<T> : IResourceStore where T : Resource
{
    private List<Resource> _store;

    public IEnumerable<Resource> Store { get { return _store; } } 

    public void AddResource(Resource resource)
    {
        _store = new List<Resource>();
        _store.Add(resource);
    }
}

，最后是专门的商店WoodStore，其中AddResource方法应只接受Wood:

and finally a specialised store WoodStore where the AddResource method should only accept Wood:

public class WoodStore : ResourceStore<Wood>
{

}

为了完整起见，接口IResourceStore由可以充当资源存储库的任何东西实现:

For completeness the interface IResourceStore which is implemented by anything that can act as a Resource Store:

public interface IResourceStore
{
    void AddResource(Resource resource);
}

如果我运行一个小的控制台应用程序并执行以下操作，则在尝试将Wheat添加到WoodStore时会出现错误.但事实并非如此，实际上输出显示WoodStore现在包含木材和小麦.这是控制台应用程序:

If I run a little console application and do the following I would have expected an error when trying to add Wheat to a WoodStore. But it doesn't and in fact the output shows that the WoodStore now contains Wood and Wheat. This is the console app:

class Program
{
    static void Main(string[] args)
    {
        WoodStore store = new WoodStore();
        store.AddResource(new Wood(10));
        store.AddResource(new Wheat(5));

        foreach (Resource resource in store.Store)
        {
            Console.WriteLine("{0} {1}", resource.GetType(), resource.Count);
        }

        Console.ReadLine();
    }
}

最后，这里是Wheat，只是为了完整性，尽管没有什么特别之处:

Finally here is Wheat just for completeness although there is nothing special about it:

public class Wheat : Resource
{
    public Wheat(int resourceCount) : base(resourceCount)
    {
    }
}

我显然在这棵树上叫错了树，希望对我如何限制WoodStore只接受Wood提供任何帮助.最终，会有很多不同的商店受到一定的限制，我正在寻找一种通用的处理方法.

I'm obviously barking up the wrong tree on this one, and would appreciate any help as to how I would go about restricting WoodStore to only accept Wood. Ultimately there will be a lot of different stores that would have certain restrictions and I'm looking for a way to handle this generically.

非常感谢.

推荐答案

您的接口需要通用，您需要在后备存储中使用T，而且AddResource中的new List也不是您想要的我敢打赌:

Your interface needs to be generic and you need to use T in the backing store, also the new List in AddResource is not what you want I bet:

public interface IResourceStore<T> where T : Resource
{
    void AddResource(T resource);
}

public class ResourceStore<T> : IResourceStore<T> where T : Resource
{
    private List<T> _store = new List<T>();

    public IEnumerable<T> Store { get { return _store; } } 

    public void AddResource(T resource)
    {
        //_store = new List<T>(); //Do you really want to create a new list every time you call AddResource?
        _store.Add(resource);
    }
}

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