Pattern for Exposing Interface Property as Interface

Question

In the code below I'd like to expose property Bristles of Hedgehog as an IBristles in the IHedgehog interface, because a) that way I can just expose the getter and b) in external assemblies I don't have to reference all the assemblies that Bristles uses for more complicated methods like FindBristleDNA. This is what intuitively seems the right way to do it:

// straightforward interface for simple properties of Bristles -- 
// more complicated methods not exposed
public interface IBristles   {
    int Quantity{ get;  }
}
public class Bristles : IBristles {        

    public int Quantity{ get; set; }
    public MyObscureAssembly.ComplicatedObject FindBristleDNA(){ ... }
}

// simple interface for Hedgehog, which in turn exposes IBristles
public interface  IHedgehog {
    bool IsSquashed { get; }
    IBristles Bristles { get; }
}
// Here, Hedgehog does not properly implement IHedgehog, even though
// Bristles implement IBristles. Will not compile.
public class Hedgehog : IHedgehog {
    public bool IsSquashed { get; set; }
    public Bristles Bristles { get; set; }
}

My choices are either to expose Bristles directly on the IHedgehog interface (which I don't want to do), or to create another property with a different name (which I don't really want to do either, I'd like IHedgehog to have the property Bristles, in the same way the IBristles has the property IsSquashed.)

public interface  IHedgehog {
    bool IsSquashed { get; }
    IBristles ReadOnlyBristles { get; }
}
public class Bar : IBar    {
    public bool IsSquashed { get; set; }
    public Bristles Bristles { get; set; }
    public IBristles ReadOnlyBristles { get { return this.Bristles; }
}

which seems rather inelegant.

Of course, when dealing with an actual Hedgehog object we need the getter and setter fully functional, and the returned object to be a proper Bristles object. But, the IHedgehog just needs to return IBristles from the Bristles getter.

Is there a better/commonly used pattern?

Answer 1

Use explicit interface implementation:

public class Hedgehog : IHedgehog 
{
    public bool IsSquashed { get; set; }

    // your public property
    public Bristles Bristles { get; set; }

    // implements the interface
    IBristles IHedgehog.Bristles { get { return Bristles; } }
}

Answer 2

public class Hedgehog : IHedgehog 
{
    private Bristles _bristles;

    public bool IsSquashed { get; set; }

    public IBristles Bristles 
    { 
       get {return _bristles;}
       set {_bristles = value;}
    }
}

Should I think. To implement IHedgehog you need a getter that returns IBristles, not Bristles