Internal Modifier on an Interface's Property

Question

I have the following interface:

public interface IAgable {
    int Age { get; internal set; }
}

I want the Age property, to be read-only for external assemblies that reference this interface, but also I want the Age property to be set on the interface's same assembly, hence the internal modifier.

This, however, seems to throw a compilation error, as accessibility modifiers may not be used on accessors in an interface.

I want the property to be called from an interface, and I want to be able to set it at an internal level. At the same time, if referenced from an outside project, I want it to be readonly.

Is this possible?

Answer 1

Have an internal interface that provides both a get and a set, and a public interface that provides only a get. Have the public interface extend the internal interface:

public interface IAgable
{
    int Age { get; }
}

internal interface IAgableInternal : IAgable
{
    int Age { set; }
}