I have an interface and two types that derive from it.
However, I cannot do the following:
B objectB = (B) objectA
Where B derives from Interface1 (I am making up the name of classes but the point still stands), and likewise for objectA (which is of type A). I get the following error message:
Cannot cast expression of type A to B.
Both types are deriving from the interface, what am I missing?
You need to cast as the interface.
interface IBase { }
class A : IBase { }
class B : IBase { }
With this, the only thing the two types have in common is the interface members. B might have items that A does not.
A a = new A();
B b = new B();
IBase aBase = a;
IBase bBase = b;
You can then call anything on the IBase Interface.
Imagine the following setup:
public interface Human
{
bool Male { get; }
}
public class Man : Human
{
public bool HasABeard { get { return true; } }
public bool IsMale { get { return true; } }
}
public class Woman : Human
{
public bool IsMale { get { return false; } }
public List<Pair<Shoe>> Shoes { get; set; }
}
What would you expect the compiler to produce from the following code? What will the output be?
Man a;
Woman b = new Woman();
a = (Man)b;
Console.WriteLine(a.HasABeard ? "Beard ON" : "Beard OFF");