Getting most derived type of object that implements interface

[Steven Schveighoffer via Digitalmars-d-learn]

On 7/25/16 5:54 AM, Kagamin wrote:
> Cast it to Object:
>     FooInterface a = new BarImplementsInterface();
>     FooBaseClass b = new BarDerivedClass();
>     Object o = cast(Object)a;
>     writefln("a class: %s", a.classinfo.name);
>     writefln("b class: %s", b.classinfo.name);
>     writefln("o class: %s", o.classinfo.name);

Yes, for the unrelated reason that COM objects may not be D objects, 
interfaces that can only possibly be D Objects don't implicitly cast to 
Object.

-Steve