reimplementing an interface in a derived class

[bauss]

On Friday, 4 January 2019 at 09:53:18 UTC, Alex wrote:
> I assume the move method of an Animal is not abstract, and 
> therefore I supposed, casting to this type explicitly should 
> restore this very non-abstract behavior. But this is not the 
> case.
> And the final/virtual thing above explains this to some extent, 
> too... I think...

A cast is only a way to tell the compiler the signature of a type.

In most cases it actually does nothing at runtime and is just a 
way to help the compiler.

Ex.
auto b = new B;
auto a = cast(A)b;

Will just tell the compiler that all usage of a will be 
restricted to the signature of A.
It doesn't tell the compiler that all usage of a should be the 
same as A.

At runtime it would actually just be:
auto b = new B;
auto a = b;