在实现通用接口方法的方法中专门化类型

Question

I have a method in an interface that I want to specialize the types for in classes that implement that interface. Something like this:

public interface Iface
{
    Function<Some, Some> Updater<T>(Func<T, T> op) where T : Iface;
}

public class Test : Iface
{
    public Function<Some, Some> Updater<T>(Func<T, T> op) where T : Test
    {
        // Use op with parameters that are of type Test
        return null;
    }
}

This doesn't compile of course. I know I could put a type param on Iface and get it to compile, but that gets messy and so I'm wondering if there is some way to do it without that. Is there some way just from the declarations of the methods in the interface and class that can make it so I can have the subclass work with it's own type but declare it in the interface?

Answer 1

Sorry, but adding a type param to the Iface is the only way that I think that you can do this. Why do you think it is messy?

Here it is:

public interface Iface
{
    // TODO: Add non type specific methods here
}

public interface Iface<TIface> : Iface
    where TIface : Iface<TIface>
{
    // Type specific methods get defined here
    Function<Some, Some> Updater(Func<TIface, TIface> op);
}

public class Test : Iface<Test> // <- We're implementing the generic version of Iface<TIface> instead of Iface.  Note that Iface<TIface> extends Iface, so this class must implement that interface too.
{
    public Function<Some, Some> Updater(Func<Test, Test> op)
    {
        // Use op with parameters that are of type Test
        return null;
    }
}

It looks less messy to me.

Updated

I added a base Iface interface without the generics type parameter for the places where the type parameter is not needed.