Idea #1 on integrating RC with GC

[Manu]

On 6 February 2014 09:16, Adam D. Ruppe <destructionator at gmail.com> wrote:

> On Wednesday, 5 February 2014 at 22:32:52 UTC, Andrei Alexandrescu wrote:
>
>> On the face of it it seems odd that reference counted chunks of typed
>> memory are deemed useless
>>
>
> I don't think anybody has actually said that. They have their places, it
> is just useless to talk about throwing them in everywhere.
>
>  I should also add that imparting useful semantics to scope is much more
>> difficult than it might seem.
>>
>
> I'm not so sure about that*, but the fact is scope would be enormously
> useful if it was implemented.
>
> * Let's say it meant "assigning to any higher scope is prohibited". That
> should be trivially easy to check and ensures that variable itself doesn't
> escape. The tricky part would be preventing:
>
> int[] global;
> void foo(scope int[] a) {
>    int[] b = a;
>    global = b;
> }
>
>
> And that's easy to fix too: make ALL variables scope, unless specifically
> marked otherwise at the type declaration site (or if they are value types
> OR references to immutable data, which are very similar to value types in
> use).
>

Surely a simpler solution is to mark b scope too? Does that break-down at
some point?

The type declaration can be marked as a reference encapsulation and those
> are allowed to be passed up (if the type otherwise allows; e.g. postblit is
> not disabled).
>
> That would break a fair chunk of existing code**, but it'd make memory
> management explicit, correct, and user extensible.
>
> ** I think moving to not null by default at the same time would be good,
> just rip off teh whole band aid.
>
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