13-May-2013 02:47, Walter Bright пишет:
On 5/12/2013 1:48 PM, Dmitry Olshansky wrote:
13-May-2013 00:28, Walter Bright пишет:
On 5/12/2013 6:01 AM, Andrei Alexandrescu wrote:
Bartosz, Walter and I reached a similar design a few years ago. We
just thought
it complicates things too much for what it does.
I've been working in the background on a scheme that can infer
uniqueness. The beauty of it is it will not require visible language
changes - it's just that things that didn't compile before now will.
Good things these are, but that adds up to what a programmer should
know or we
are stuck trying out combinations that might work until we hit it.
I think programmers will find it to be intuitive, not magical.
By the end of day we need guarantees not intuition which is the problem.
Compare the statement in the would be standard of D:
"If the compiler can prove that the expression is unique it's implicitly
convertible to shared/immutable/const."
vs
"The following rules define what kinds of if the expression is unique.
[...] Unique expression is convertible to shared/immutable/const."
The keyword "the compiler can prove" - it doesn't state anything
reliable. In the long run I'd prefer the second and exact formal rules
and if they are too hard to explain we'd better not do it at all.
--
Dmitry Olshansky
