nested class inheritance

[Christophe Travert]

Andrei Alexandrescu , dans le message (digitalmars.D:172280), a écrit :
>> For Fruit.Seed it's Fruit, for AppleSeed it's Apple. This makes sense
>> because the Apple, which AppleSeed sees is the same object, which
>> Fruit.Seed sees as it's base type Fruit.
> 
> That would mean AppleSeed has two outer fields: a Fruit and an Apple.

Only one. Apple. And when AppleSeed.super seed this Apple, it sees a 
fruit.

AppleSeed a;
assert(is(typeof(a.outer) == Apple));
assert(is(typeof(a.super) == Seed));
assert(is(typeof(a.super.outer) == Fruit));
//but:
assert(a.outer is a.super.outer);

If you can't figure out how can a.outer and a.super.outer have two 
different types, but be the same, think about covariant return.