D Language 2.0

[Craig Black]

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