On 2009-10-13 18:26:04 -0400, Bartosz Milewski
<bartosz-nos...@relisoft.com> said:
I didn't so much "decline to contribute" as hit a wall. I'm a bit of a
perfectionist and it's hard for me to subscribe to the "good enough"
philosophy (as long as it's better that C++, it's fine for D). My
impression is that, as the release of D2 and the publication of
Andrei's book are nearing, this attitude is gaining ground. I try to
fight this attitude but it's an uphill battle. Or, as Andrei puts it, I
start whining and give up ;-).
I don't like that attitude either. I'd rather remove completely an
unfinished feature than leave it there half-done. If the main feature
of D2 is a new concurrency model, then leaving things in the state they
are now isn't going to impress much.
The semantics of "shared." I can live with postponing the
implementation of the race-free type system, but not with the compiler
inserting barriers around all shared reads and writes, even inside
synchronized sections.
I hadn't thought about that, but it's somewhat ridiculous. On my part
I'm more preoccupied by the absence of lent semantics as it goes much
deeper than concurrency: you need it to implement proper invariant
constructors and unique references.
The C++-derived template metaprogramming mess. Especially when C++0x
provides better support for variadic templates than D (see my upcoming
blog). I fought successfully for non-functional approach to string
mixins. The same is needed for more general templates. In my opinion,
there should not be any part of the language that is understandable
only by seasoned library writers.
I'm quite eager to read about that.
The "better than Java" aspect of D ignores the latest development in
Java. In particular the work on non-null pointers and the use of
annotations for type-system extensions. Annotations are being added to
D as we speak because it finally became obvious that no amount of
cleverness can make object properties work without additional syntax.
So the patching begins, without a clear vision of the role of
annotation in future D.
I'm not even sure what convinced Walter to put annotations in and what
they're supposed to be capable of. I hope it's not just a new way to
create keywords without them really being keywords.
As far as my thread work went, I had an almost working implementation
of spawn, except for a nasty compiler bug which resisted all efforts to
reduce it to a simple test case. Threads also required some clever work
with templates (testing arguments to "spawn" for sharing violations). I
implemented typelist.d in Phobos to make it easier, and learned how
inflexible D templates were. At least they are better than C++, or are
they?
I'm not that satisfied with D templates either. You can use them in
mixins to achieve pretty amazing things, but I've been hindered by the
visibility rules with non-mixin templates and how templates with alias
arguments are difficult to instantiate in certain contexts.
If it were me in charge of the D2 project, given the approaching
deadline, I'd scrap the new concurrency model completely (including
immutable, unless we are given a way to write safe constructor for it)
and focus on everything else. In my view, that's better than leave it
in the state it is now. (Note that I'm speaking of the model at the
compiler level, creating new library code is a perfectly fine idea.)
--
Michel Fortin
michel.for...@michelf.com
http://michelf.com/
