T[new]

[Stewart Gordon]

Walter Bright wrote:
<snip>
> Under the hood, a T[new] will be a single pointer to a library defined 
> type. This library defined type will likely contain three properties:
> 
>     size_t length;
>     T* ptr;
>     size_t capacity;
> 
> The usual array operations will work on T[new] as well as T[].
<snip>

Would new T[10] allocate this structure and the array data on a single 
GC block, or on two separate blocks?  And when the array is reallocated, 
will the structure move with it?

I suppose it depends on whether you want T[new] to be
(a) something whereby all references persist as the array is reallocated 
(b) merely a reference to an allocated array as opposed to an array slice

If (a), this is currently achievable with a T[]*.

If (b), what might work well is a structure like

     size_t length;
     size_t capacity;
     T[capacity] data;

meaning still only one allocation and only one level of indirection when 
one is used.  And the T[new] variable itself would simply hold &data[0].

Moreover, would whatever happens solve such const/invariant holes as bug 
2093?

Stewart.