Is there any way to make a default constructor of a struct container allocate/initialize an internal pointer?

I need this in a container with RC behaviour similar to

struct Container
{
    this()    // this is currently forbidden:
    {
        _rcStore = emplace(cast(RCStore*)malloc(RCStore.size), null, 0);
    }

private:
    static struct RCStore
    {
        T* store;
        size_t refCount;
    }
    RCStore* _rcStore;
}

If I can't modify default construction in containers such as `Container` it is gonna behave in the same confusing way as empty AA's do for (novel) D developers. Namely that the assignment of uninitialized AA's has copy semantics and non-empty AA's have reference semantics.

I believe Andralex has spoken about this being a problem that should be fixed if possible.

On 9/21/16 8:49 AM, Nordlöw wrote:
> Is there any way to make a default constructor of a struct container
> allocate/initialize an internal pointer?
>
> I need this in a container with RC behaviour similar to
>
> struct Container
> {
>     this()    // this is currently forbidden:
>     {
>         _rcStore = emplace(cast(RCStore*)malloc(RCStore.size), null, 0);
>     }
>
> private:
>     static struct RCStore
>     {
>         T* store;
>         size_t refCount;
>     }
>     RCStore* _rcStore;
> }
>
> If I can't modify default construction in containers such as `Container`
> it is gonna behave in the same confusing way as empty AA's do for
> (novel) D developers. Namely that the assignment of uninitialized AA's
> has copy semantics and non-empty AA's have reference semantics.
>
> I believe Andralex has spoken about this being a problem that should be
> fixed if possible.

Sadly, not currently. I realize this makes certain designs more difficult. -- Andrei