有关.NET中接口继承的一个问题 [英] A question about interface inheritance in .NET

问题描述

让我们在接口的IQueryable＆LT; T＆GT; 例如：

public interface IQueryable<T> : IQueryable, IEnumerable;

由于IQueryable的依次实现IEnumerable

Since IQueryable in turn implements IEnumerable:

public interface IQueryable : IEnumerable;

为什么在第一次申报，IQueryable的已经明确的实现IEnumerable呢？这是从类继承不同，你不必从一个祖父母？

why in the first declaration, IQueryable has to explicitly implement IEnumerable as well? This is different from class inheritance where you do not have to explicitly inherit from a "grandparent"?

推荐答案

这是不正确的。我怀疑你对这些类右击/在Visual Studio界面，点击转到定义，这是什么的元的告诉你。如果你想真正了解发生了什么，这里有一个例子：

This is not true. I suspect you are right-clicking on these classes/interfaces in Visual Studio and clicking on "Go to definition," and this is what the metadata is telling you. If you want to really understand what's happening, here's an example:

    public interface IAddTwo
    {
        int AddTwo(int x);
    }

    public interface IAddTwoOrThree : IAddTwo
    {
        int AddThree(int y);
    }

    public class AddTwoOrThree : IAddTwoOrThree
    {
        public int AddTwo(int q)
        {
            return q + 2;
        }

        public int AddThree(int z)
        {
            return z + 3;
        }
    }

需要注意的是最后一堂课只需要实现一个接口（但如果你离开了，你得到一个编译错误两种方法。

Note that the last class only has to implement one interface (but that you get a compiler error if you leave off either method.

创建如上一个类库，通过浏览到结果DLL添加引用（而不是通过向项目的引用），并查看元数据AddTwoOrThree。你会看到

Create the above as a class library, add a reference by BROWSING to the resulting DLL (not by adding a reference to the project), and view the metadata for AddTwoOrThree. You will see

AddTwoOrThree : IAddTwoOrThree, IAddTwo

中提琴！这就是为什么你看到你所看到的MSDN上的东西。他们展示了元数据，而不是他们的codeRS写了code的方式。

Viola! This is why you see what you are seeing on MSDN. They show the metadata, not the way their coders wrote the code.

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