覆盖接口的返回类型

Question

here's hoping this can be done!

I have an base interface

interface IEntity
{
    IConfiguration Configuration {get; set;}
}

And an abstract class

abstract class Entity
{
    abstract IConfiguration Configuration {get; set;}
}

Now I'll introduce a "Client" that inherits from "Entity"

interface Client : Entity
{

}

Clients have a child class of "Configuration"

interface IClientConfiguration : IConfiguration
{

}

So lastly, I'd like my Client class to look like this

class Client : IClient
{
    public IClientConfiguration Configuration {get; set;}
}

The problem is, C# is complaining that I'm not returning an IConfiguration for class Client. I can override this by declaring new public IClientConfiguration... but before I go that route, I'd like to know if there is a better way to structure this and maintain best practices.

Thanks for any help! --Michael

Answer 1

You could use explicit interface implementation in your Client class:

class Client : IClient
{
    public IClientConfiguration Configuration { get; set; }

    // Explicit implementation
    IConfiguration IEntity.Configuration 
    { 
        get { return this.Configuration; }
        set { /* what to do here? */ }
    }
}

This is common practice when implementing IEnumerable<T> since that interface extend IEnumerable . Both of these interfaces declare a method called GetEnumerator but with different return types ( IEnumerator<T> vs IEnumerator ).

However, I think you've made a design error somewhere. The configuration property is get/set. That gives the impression that your Client class must be able to accept a configuration of any kind. At the same time it seems as if your Client class only work with IClientConfiguration values. Confusing.

Answer 2

I think you may have missed adding "IEntity" interface to your "Entity" class.

abstract class Entity : IEntity
{
    abstract IConfiguration Configuration {get; set;}
}