radical ideas about GC and ARC : need to be time driven?

[Xavier Bigand via Digitalmars-d]

Le 12/05/2014 06:26, Marco Leise a écrit :
> Am Mon, 12 May 2014 03:36:34 +1000
> schrieb Manu via Digitalmars-d <digitalmars-d at puremagic.com>:
>
>> On 12 May 2014 02:38, Marco Leise via Digitalmars-d
>> <digitalmars-d at puremagic.com> wrote:
>>> Am Sun, 11 May 2014 14:52:50 +1000
>>> schrieb Manu via Digitalmars-d <digitalmars-d at puremagic.com>:
>>>
>>>> On 11 May 2014 05:39, H. S. Teoh via Digitalmars-d
>>>> <digitalmars-d at puremagic.com> wrote:
>>>>> On Sat, May 10, 2014 at 09:16:54PM +0200, Xavier Bigand via Digitalmars-d wrote:
>>>>>>   - Same question if D migrate to ARC?
>>>>>
>>>>> I highly doubt D will migrate to ARC. ARC will probably become
>>>>> *possible*, but some language features fundamentally rely on the GC, and
>>>>> I can't see how that will ever be changed.
>>>>
>>>> Which ones are incompatible with ARC?
>>>
>>> Pass-by-value slices as 2 machine words
>>
>> 64bit pointers are only 40-48 bits, so there's 32bits waste for an
>> offset... and if the base pointer is 32byte aligned (all allocated
>> memory is aligned), then you can reclaim another 5 bits there... I
>> think saving an arg register would probably be worth a shift.
>> 32bit pointers... not so luck :/
>> video games consoles though have bugger all memory, so heaps of spare
>> bits in the pointers! :P
>
> And remember how people abused the high bit in 32-bit until
> kernels were modified to support the full address space and
> the Windows world got that LARGE_ADDRESS_AWARE flag to mark
> executables that do not gamble with the high bit.
>
> On the positive side the talk about Rust, in particular how
> reference counted pointers decay to borrowed pointers made me
> think the same could be done for our "scope" args. A reference
> counted slice with 3 machine words could decay to a 2 machine
> word "scoped" slice. Most of my code at least just works on the
> slices and doesn't keep a reference to them. A counter example
> is when you have something like an XML parser - a use case
> that D traditionally (see Tango) excelled in. The GC
> environment and slices make it possible to replace string
> copies with cheap slices into the original XML string.
>
I don't really understand why there is no parser with something like 
slices in a language without GC. It's not possible to put the array to a 
more globally place, then the parser API will use 2 indexes instead of 
the buffer as parameter?