pass-by-ref semantics for structs (was Deque impl.)

[David Nadlinger]

On Thursday, 31 January 2013 at 19:55:01 UTC, Robert burner 
Schadek wrote:
> Just use a payload struct and check whether that is null before 
> every operation.

The following problem is inherent to this approach:

---
struct Array(T) {
   static struct Payload {
     T* data;
     size_t length;
   }
   Payload* p;
   // ...
}

void fill(T)(Array!T a) {
   a.length = 3;
   a[0] = 1;
   a[1] = 2;
   a[2] = 3;
}

void client() {
   Array!int a;
   fill(a);
   // Oops, a is still empty (with null payload).
}
---

Such containers are "almost, but not quite" reference types; 
reason enough to @disable this() in order to improve the user 
experience, in my opinion.

David