Question

I just discovered, quite by accident, that this seems to work:

Public Interface Ix     ReadOnly Property TestProp() End Interface  Public Interface Iy     Property TestProp() End Interface  Public Sub TestSub     Dim x As Ix = Me.InstantiationNotImportant()     Dim y As Iy = CType(x, Iy) End Sub 

Maybe I’ve written a bit too much code today, but this doesn’t make sense to me. How is it possible that I can convert one interface to another one that is even slightly different?

Any thoughts?

EDIT: It appears that I was indeed just light-headed from too much coding. After a little sleep, the world makes sense again. 🙂

Answer 1

Like Garry said Instantiation is important because if I do this:

public interface IX { } public interface IY { } public class Test : IX { } 

The following won’t work.

IX xvar = new Test(); IY yvar = xvar as IY; \\Returns null.  IY yvar = (IY)xvar; \\Throws cast exception. 

it runs but yvar will be null because the cast is not possible, but if you declare test like this:

public class Test : IX,IY { } 

It will now work, as Test uses both interfaces and casting from the object in xvar to Y is valid.