On Monday, 16 November 2015 at 09:42:43 UTC, Ola Fosheim Grøstad
wrote:
On Monday, 16 November 2015 at 09:04:33 UTC, Joseph Cassman
wrote:
[...]
The D designers might want to look at Pony lang's capability
system, which has been proven sound. It has 6 different
aliasing capabilites that regulates among other things
transition from mutable to immutable.
D is a little bit better of (if it does not allow casting away
const) than C++, because in C++ const is essentially "shared
const", whereas in D in is "local const with potential
aliasing". AFAIK the D sementics is that no other thread can
hold a mutable reference to something you have as const. But it
is still a relatively weak guarantee. In C you have
"restricted" for notifying the compiler that the resource is
aliasing free within the context.
You described immutable, not const. If one thread has a const
reference, it's entirely possible another thread has a mutable
reference.
Atila
