What are the advantages of explicit interface implementation in C#?

Question

C# supports built-in mechanism for differentiating methods that have the same names. Here is a simple example below shows how it works:

interface IVehicle{
    //identify vehicle by model, make, year
    void IdentifySelf();    
}

interface IRobot{
    //identify robot by name
    void IdentifySelf();
}

class TransformingRobot : IRobot, IVehicle{ 
    void IRobot.IdentifySelf(){
        Console.WriteLine("Robot");
    }

    void IVehicle.IdentifySelf(){
       Console.WriteLine("Vehicle");
    }
}

What are the use cases or benefits of this distinction? Do I really need to differentiate abstract methods in implementing classes?

Answer 1

In your case, there's no real benefit, in fact having two methods like that is just confusing to the user. However, they are key when you have:

interface IVehicle
{
    CarDetails IdentifySelf();    
}

interface IRobot
{
    string IdentifySelf();
}

Now we have two methods of the same name, but different return types. So they cannot be overloaded (return types are ignored for overloading), but they can be explicitly referenced:

class TransformingRobot : IRobot, IVehicle
{
    string IRobot.IdentifySelf()
    {
        return "Robot";
    }

    CarDetails IVehicle.IdentifySelf()
    {
        return new CarDetails("Vehicle");
    }
}