D array expansion and non-deterministic re-allocation
Andrei Alexandrescu
SeeWebsiteForEmail at erdani.org
Tue Nov 17 18:47:44 PST 2009
Bartosz Milewski wrote:
> Walter Bright Wrote:
>
>> BCS wrote:
>>> would you agree that it is not something the programer can predict in
>>> advance?
>> He can, but it is not reasonable to expect him to. But it's still
>> deterministic.
>
> I've been following this discussion about determinism and I think it addresses the problem from the wrong point of view, that of a specific implementation.
>
> My concern is the semantics of the language. As it is defined right now, a conforming implementation is free to use a quantum random number generator to decide whether to re-allocate or not. Is it likely? I don't think so; but the non-determinism is part of the semantics of D arrays.
It would not be difficult to specify in the language definition (and
TDPL) that behavior is deterministic for a given platform. I think this
has some impact on the freedom of the memory allocator, but probably not
major.
Andrei
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