On Tuesday, 22 March 2016 at 11:00:44 UTC, Jonathan M Davis wrote:
That's funny. I would have said that those were _advantages_
for D. D's constness can certainly be unwieldy (some sort of
equivalent to C++ mutable would be a very welcome addition if
we could pull it off), but whatever flaws D's const may have,
the transitivity is a huge plus overall IMHO, and I would have
said that the struct/class split was a huge win. It properly
segregates the inheritance stuff to reference types while not
forcing all user-defined types of any complexity to be
reference types.
So, while I'm quite sure that Rust has advantages over D, I
would not have listed those among them.
- Jonathan M Davis
Rust doesn't need D-style transitive const because it can be
replicated using variable bindings and ownership. When you create
an object and only assign it immutable binding for it it's
transitively immutable forever. Tail mutability can be achieved
by wrapping a field in std::Cell:
https://doc.rust-lang.org/std/cell/ . Imo much less invasive than
D's constness.
Rust doesn't have implementation inheritance yet, so no
class/struct split. We'll see how they deal with that, various
proposals are made.
