Null references redux

[Nick Sabalausky]

"Jeremie Pelletier" <jeremiep at gmail.com> wrote in message 
news:h9mmre$1i8j$1 at digitalmars.com...
> Ary Borenszweig wrote:
>>
>> Object is not-nullable, Object? (or whatever syntax you like) is 
>> nullable. So that line is a compile-time error: you can't cast a null to 
>> an Object (because Object *can't* be null).
>>
>
> union A {
> Object foo;
> Object? bar;
> }
>
> Give me a type system, and I will find backdoors :)
>

Unions are nothing more than an alternate syntax for a reinterpret cast. And 
it's an arguably worse syntax because unlike casts, uses of it are 
indistinguishable from normal safe code, there's nothing to grep for. As 
such, unions should never be considered any more safe than cast(x)y. The 
following is just as dangerous as your example above and doesn't even touch 
the issue of nullability/non-nulability:

union A {
int foo;
float bar;
}