Non-null objects, the Null Object pattern, and T.init

[Timon Gehr]

On 01/19/2014 01:03 PM, Michel Fortin wrote:
> Actually, 'A?' would implicitly convert to 'A' where the compiler can
> prove control flow prevents its value from being null.

I think the type should be upgraded. i.e.:

> So you can
> dereference it in a branch that checked for null:
>
>      class A { int i; void foo(); }
>      void bar(A a); // non-nullable parameter
>
>      void test(A? a, A? a2)
>      {
>          a.i++; // error, 'a' might be null
>          a.foo(); // error, 'a' might be null
>          bar(a); // error, 'a' might be null
>
>          if (a)
>          {
                static assert(is(typeof(a)==A));
>              a.i++; // valid [...]
>              a.foo(); // valid [...]
>              bar(a); // valid [...]
>          }
>      }