D Language 2.0

[Andrei Alexandrescu]

Craig Black wrote:
> Leandro Lucarella Wrote:
> 
>> Andrei Alexandrescu, el 19 de enero a las 23:17 me escribiste:
>>> bearophile wrote:
>>>> Andrei Alexandrescu:
>>>>> I'd love -nogc. Then we can think of designing parts of Phobos
>>>>> to work under that regime.
>>>> But you must do this with lot of care: programmers coming from C++ will
>>>> be tempted to write code that uses those GC-free parts of Phobos a lot,
>>>> the end result will be a lot of D code in the wild that's like C++ or
>>>> worse. So when you want to use one of those modules or libraries, you
>>>> may need to dance their no-GC dance. This can invalidate the good idea
>>>> of designing a GC-based language.
>>>>
>>>> A better strategy is first of all to improve a lot the D GC, if
>>>> necessary to introduce in the language other details to help the design
>>>> of a more efficient GC (like giving ways to tell apart pinned objects
>>> >from normal ones, make the unpinned ones the default ones, and modify
>>>> the type system so mixing pinned-memory and unpinned-memory pointers is
>>>> generally safe, etc). Only when further improvements to the GC become
>>>> too much hard, you can start to write no-GC parts of Phobos, few years
>>> >from now.
>>>> I have seen many cases where Java code run with HotSpot is faster than
>>>> very similar D1 code compiled with LDC. Avoiding the GC is a easy
>>>> shortcut, but I think it's not a good long-term strategy for D.
>>>>
>>>> Bye,
>>>> bearophile
>>> Walter and I talked for hours about a no-gc model for D, and the
>>> conclusion was that with only a little compiler support, things can
>>> be arranged such that swapping different object.d implementations,
>>> the entire D allocation model can be swapped between traditional GC
>>> and reference counting.
>> Again? RC is *not* -nogc, is -anothergc. And reference counting won't do
>> the trick unless you add a backing GC to free cycles. What I mean about
>> -nogc is *no* GC, is "please, mr compiler, give me an error when a GC
>> facility is used".
> 
> Yeah, this is what I thought -nogc meant as well.  Not that I don't think that reference counting wouldn't be useful, but reference counting has its own problems.  I would be interested in a -refcounting option or something like that though.  It would be useful to compare the performance of the two systems.
> 
> -Craig

The actual option used would be one that selects which object.d should 
be used (even -I works). Comparing and contrasting would be a matter of 
compiling with different flags.

I'm glad this is being discussed. I'd forgotten many details of how I 
was thinking of doing this.


Andrei