Low-Lock Singletons In D

[bearophile]

Max Samukha:

> The question is what should be the result of:
>
> Nullable(int*)?
> Nullable!(Nullable!T)?
>
> Forbidden (like in C#)? Aliased to the source type? A distinct 
> type?

In D Nullable!(int*) needs to be a different type, because the 
interface is different between a pointer and a Nullable.

But often you want to use something like Nullable(int*, null) or 
Nullable(int*, cast(int*)null) instead.

In the second case maybe it can be collapsed into a single 
Nullable, but such behavior needs to be documented.

Bye,
bearophile