Am 15.03.2015 um 08:44 schrieb Walter Bright:
On 3/14/2015 10:23 PM, deadalnix wrote:
On Sunday, 15 March 2015 at 05:08:54 UTC, Walter Bright wrote:
On 3/14/2015 8:50 PM, deadalnix wrote:
Const is the inconvenience of immutability without its benefit. That
would be a
poor default, IMO.
It's utility is in self-documenting encapsulation.
It also turns out that it offers optimization possibilities for ARC
systems.
You'll have to explain yourself, as there is nothing obvious here.
I see how immutable can be leveraged to optimize, but I don't think
const offers
the same capabilities.
"const ref" can tell the optimizer that that path for a ref counted
object cannot alter its ref count.
My proposal would be to make "scope" (with strong recursive guarantees)
the default instead to achieve that goal. That would give the compiler a
lot of optimization potential (much more than just for RC), and would at
the same time most probably be a lot less limiting. It would also be a
nice documentation trait to see where references are stored for later
use. And it could even be used to implement checked safety for calling
C/C++ functions with GC references.
I agree with Dicebot that any such change should ideally be done as a
single big step for all attributes at once. However, instead of a major
version bump, we could have a normal deprecation path à la "opt-in only"
-> "opt-in + opt-out" -> "opt-out only" -> remove old defaults.
