使用扩展类的静态属性扩展泛型接口[duplicate](Extending a generic interface with a static property of the extended class [duplicate])

 
 
 这个问题在这里已有答案： 
 
 
 
  
 为什么C＃不允许静态方法实现接口？ 24个答案 
 
 
 
 
 我有一个通用的接口，我希望有一个self类型的属性 
 
public interface IFoo<TBar> : where TBar : ISomething 
    {
        TBar Prop1 { get; set; }
        IFoo<TBar> Unset { get; }
    }
 
 这是好的，直到我继承这个并创建一个（非泛型）类： 
 
public class FooDesired : IFoo<Bar>
    {
        public Bar Prop1 { get; set; }
        public static Foo Unset { get { return new Foo(); } }
    }

public class FooReality : IFoo<Bar>
    {
        public Bar Prop1 { get; set; }
        public static IFoo<Bar> Unset { get { return new Foo(); } }
        public IFoo<Bar> IFoo<Bar>.Unset { get { return new Foo(); } }
    }
 
 我目前的实现有两个问题： 
 
 1.此实现不实际允许Unset为静态。 我已经通过显式接口实现来解决这个问题，但我总是对“欺骗”系统持谨慎态度。 
 
 2.如果我调用Foo.Unset我总是要把它强制转换回Foo（除非我设置了一个隐式运算符，但这只是隐藏问题而不是解决它）。 
 
 编辑真实问题：如何在一组类中强制存在静态属性？ 
 
 **编辑：**对于那些热衷于用例的人，让我们假设所有动物物种一旦完全成熟就会在其体内有一定数量的骨骼。 因此，我希望Animal在Cat，Dog和Human上强制执行静态NumBones属性。 这不包括原始类'类型的静态属性，但注释与答案有良好的链接。 

 
 
This question already has an answer here:
 
 
 
  
 Why Doesn't C# Allow Static Methods to Implement an Interface?  26 answers  
 
 
 
 
I have a generic interface which I would like to have a property of type self i.e. 
 
public interface IFoo<TBar> : where TBar : ISomething 
    {
        TBar Prop1 { get; set; }
        IFoo<TBar> Unset { get; }
    }
 
This is fine until I inherit this and create a (non-generic) class:
 
public class FooDesired : IFoo<Bar>
    {
        public Bar Prop1 { get; set; }
        public static Foo Unset { get { return new Foo(); } }
    }

public class FooReality : IFoo<Bar>
    {
        public Bar Prop1 { get; set; }
        public static IFoo<Bar> Unset { get { return new Foo(); } }
        public IFoo<Bar> IFoo<Bar>.Unset { get { return new Foo(); } }
    }
 
I have two issues with the current implementation of this:
 
1. This implementation does not actual allow Unset to be static. I've worked my way around that with Explicit Interface Implementation but I'm always wary of "tricking" the system.
 
2. If I call Foo.Unset I always have to cast it back to Foo (unless I setup an implicit operator but that's just hiding the issue rather than solving it).
 
Edited Real Question: How can I enforce the existence of a static property in a set of classes?
 
**Edit: ** For those who are keen for a use case, let's assume all Animal species have a set number of bones in their bodies once fully mature. Therefore I would like Animal to enforce a static NumBones property on Cat, Dog and Human. This doesn't cover the static property being of the original class' type but the comments have good links to answers to that.

原文：https://stackoverflow.com/questions/36691294