Is the other-kind-of-null really necessary in Nullable and Variant?

[Idan Arye]

On Monday, 29 April 2013 at 15:39:47 UTC, Simen Kjaeraas wrote:
> On 2013-04-29, 17:34, Idan Arye wrote:
>
>> On Monday, 29 April 2013 at 12:23:04 UTC, deadalnix wrote:
>>> On Sunday, 28 April 2013 at 16:33:19 UTC, Idan Arye wrote:
>>>> When you use `std.typecons.Nullable` with a type that 
>>>> already accept `null` values, you get two types of nulls - 
>>>> the `Nullable`'s null state the the regular type's `null`:
>>>>
>>>>   Nullable!string a;
>>>>   writeln(a.isNull()); //prints "true"
>>>>   a = null;
>>>>   writeln(a.isNull()); //prints "false"
>>>>   a.nullify();
>>>>   writeln(a.isNull()); //prints "true"
>>>>
>>>
>>> All types should be non nullable. Problem solved.
>>
>> *All* types? Even object references and pointers?
>
> That would be nice, yes.

And what would they be initialized to? When you write:
     Object obj;
what will `obj` refer to?

Also, what about the C&C++ interface? Without null values, how 
can you use an extern function that accepts or returns pointers?