Question

I was wondering if there was a way to cast a interface property in a derived class, for example:

public interface IImageGenerator
{
    object FinalImage { get; set; }
}

public MyClass : IImageGenerator
{
    public Image FinalImage{ get;set; }  // Its cast as Image instead of Object
}

If things are setup in the interface as objects I have to do FinalImage as Image all over the place and was wondering if there was a way to not do that. The only other thing I can think is to create a property in the derived class that returns the interface property as a Image representation e.g.

public Image MyCastProperty
{
    get {return FinalImage as Image;}
}

Answer 1

You can do this:

public interface IImageGenerator
{
    object FinalImage { get; set; }
}

public MyClass : IImageGenerator
{
    public Image FinalImage{get;set;}

    object IImageGenerator.FinalImage
    {
        get { return FinalImage; }
        set
        {
            if (!(value is Image))
            {
                throw new ArgumentException("Must be an image");
            }
            FinalImage = (Image) value;
        }
    }
}

Alternative – and preferably – make the interface generic:

public interface IImageGenerator<T>
{
    T FinalImage { get; set; }
}

Do you really need IImageGenerator to have a setter in the property though? That doesn’t sound like something I’d expect for a generator.