On 2009-10-12 11:45:55 -0400, Andrei Alexandrescu
<seewebsiteforem...@erdani.org> said:
Occasionally people here ask for ways in which they can help D. One
thing that would be extremely helpful at this point would be to help
defining and implementing D's new concurrency API. Unfortunately,
Bartosz has declined to contribute. That leaves Walter, Sean, Don, and
participants to this group to do it.
So Bartosz quit? Not that much surprising given the all too many
missing building blocks.
I recently realized that you can easily implement unique in a library.
It can work pretty much the same as auto_ptr in C++. But to guaranty
uniqueness you need either to rely on convention (as in C++), or add
support for lent to the compiler.
I know we discussed at length how lent could be implemented, we called
it 'scope' and 'escape analysis' at the time and the conclusion you
(and Walter I guess) came with was that it was too much for D2.
Well, without lent (and thus without unique), safe message passing
systems across threads will be limited to immutable data, or copied
data, which not at all useful in many situations.
Now if you want a good concurrency API relying on convention, then
that's great: there are plenty of examples to follow out there. But if
you want it to be both safe (enforced) and useful at the same time,
that's a mission impossible with the current set of tools available
from the compiler.
That's why I'm not surprised Bartosz declined to implement it.
(And sorry if I sound pessimistic.)
--
Michel Fortin
michel.for...@michelf.com
http://michelf.com/
