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
