Deque impl.

[Andrei Alexandrescu]

On 1/31/13 3:46 AM, monarch_dodra wrote:
> Quite frankly, I'm bringing more and more into question the fact that
> everything in phobos are structs, especially considering the "no default
> constructor" problem.
>
> The containers in std.container pretty much emulate final classes via
> pointers to payloads anyways. Not doing it via classes only brings
> problems.
>
> And even if you succeed in coding the damn thing correctly (Objects like
> DList had so many bugs I consider it virtually unusable). The end result
> is subtle user bugs when passing containers, if they have not been
> initialized yet. It creates an ambiguity in behavior if or if not the
> container is initialized (modification to the container inside the
> function may or may not modify the outside container).
>
> The only argument I see in favor of structs, is the possibility of
> having a deterministic memory model (std.container.Array). I don't think
> D's *generic* containers should do that though, IMO. It also brings lots
> of problems, just for a specific use case.
>
> Long story short, I'd say that unless you have a damn good reason to
> stay with structs, use classes. It has easier user semantics and much
> less room for implementation bugs.

We should use structs.

Many people who need containers have efficiency as a primary concern. It 
makes sense for the standard library to make containers as good as 
possible.

The intended semantics of containers in stdlib is reference counted with 
reference semantics. Yes, there are disadvantages for that. After much 
deliberation it seemed to me this is the best approach to containers in 
a language that cares for efficiency.

Reference counting and adding allocators later rule out final classes.


Andrei