防止调用基类实现的接口方法派生类C＃ [英] Prevent calling base class implemented interface method in the derived class C#

问题描述

是否有可能实现在一个基类的接口，并允许调用/覆盖在第一个派生类级别实现的方法，但会阻止任何进一步的派生类调用它？

Is it possible to implement an interface in a base class and allow calling/overriding the implemented method in the first derived class level but prevent calling it from any further derived classes?

    public interface IInterfaceSample
    {
        bool Test();
    }

    public class Base: IInterfaceSample
    {
        public virtual bool Test()
        {
             return True;
        }
    }

    public class Sub1: Base
    {
        //I need to be able to override the Test method here
        public override bool Test()
        {
             return True;
        }
    }

    //Under a separate project:
    public class Sub2: Sub1
    {
       //I need to prevent overriding the interface implementation in this class
    }

现在我需要的是这样的：

Now what i need is this:

    var b = new Base();
    b.Test();//This should work

    var s1 = new Sub1();
    s1.Test();//I need this to work too

    var s2 = new Sub2();
    s2.Test();//I need to prevent doing this

到目前为止，从研究，我想这也许是不可能的，因为接口必须是公开的，否则有使用它们没有真正的价值。

So far from research i think this might not be possible because interfaces has to be public, otherwise there is no real value of using them.

在我的情况，我需要一流的分公司2有访问在Sub1的，但属性只这一点，并在该类以及专门的接口实现方法的方法没有访问。

In my case, i need class Sub2 to have access to the properties in Sub1 but only that and no access to the methods on that class and specially the interface implementation methods.

只有这样，我能做到这一点是在所有未使用的接口，像这样做：

The only way i was able to do this was to not use the interfaces at all and do it like this:

    public class Base
    {
        internal virtual bool Test()
        {
             return True;
        }
    }

    public class Sub1: Base
    {
        //I am able to override the Test method here
        internal override bool Test()
        {
             return True;
        }
    }

    //Under a separate project:
    public class Sub2: Sub1
    {
       //Nothing to override here which is what i need
    }

    var b = new Base();
    b.Test();//This works

    var s1 = new Sub1();
    s1.Test();//This works too

    var s2 = new Sub2();
    s2.Test();//This is prevented

不过，我想我如果这，仍然可以用接口来实现，任何的帮助深表感谢。

However i am wondering if this is still available to achieve with interfaces, any help is much appreciated.

推荐答案

没有，这是不可能的 - 这将打破整点多态性。特别是，假设你没有使用 VAR ，但明确使用的类型：

No, this isn't possible - it would break the whole point of polymorphism. In particular, imagine you didn't use var, but used the types explicitly:

Sub1 s2 = new Sub2();
s2.Test();

这有编译：

• 第一行有编译，因为分公司2 源自 Sub1的。


• 第二行有编译，因为你想要 s1.Test（）编译，在编译时类型的 S1 是 Sub1的以及

• The first line has to compile because Sub2 is derived from Sub1.
• The second line has to compile because you wanted s1.Test() to compile, where the compile-time type of s1 is Sub1 as well.

作为经验法则，如果你有两个类X和Y，并且只的部分的X上的公共行动是有效的Y，则Y不应该从十派生你应该能够处理任何例如派生类中，如果是基类（它实现所有接口）的一个实例。

As a rule of thumb, if you have two classes X and Y, and only some of the public operations on X are valid for Y, then Y shouldn't derive from X. You should be able to treat any instance of a derived class as if it's an instance of the base class (and all interfaces it implements).

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