On Monday, 29 December 2014 at 20:42:37 UTC, Dicebot wrote:
On Monday, 29 December 2014 at 20:20:45 UTC, Steven
Schveighoffer wrote:
But this precludes doing anything with a mutable t inside foo,
since inout means "const within the function".
Hm, yes, this is indeed quite the problem. I have totally
forgot that compiler has no means of figuring out which
invocation of inout is currently used.
But something very similar feels necessary to me. There is
constness, lifetime, purity - inventing new dedicated keyword
for each case does not feel like scaling approach. Especially
when existing one is named so generic.
I've been pondering this for a while, maybe someone with a better
theoretical foundation has an answer...
These concepts you mention (I'd add "type erasure", because
that's what `inout` is currently about) are inter-connected and
have some overlap with each other. But at the same time, they are
still separate concepts.
Do you think they are just aspects of one all-encompassing Grand
Unified Concept? Because if they turn out to be fundamentally
separate, they are better treated as such, instead of mixing them
up. Dedicated keywords may be the way to go if this is the case.
(From what I've seen so far, I think they are indeed separate,
but who knows?)
In general, I get the impression from both DIP25 and DIP69 that
both are motivated by minimizing the change to the existing
language, instead of looking for the most powerful solution (that
may have other use-cases besides the ones under consideration).
I.e., instead of asking which concepts are behind the problem in
question, how these concepts could be expressed in an ideal
world, and then making compromises to fit them into D, it seems
like we're starting with some premises (as few changes as
possible, no type modifiers), and then look for a solution that
needs to sacrifice the smallest number of use cases to stay
within the constraints. This is particularly bad if our premises
are going against the nature of the problem we want to solve,
because then we are guaranteed to get a bad solution.
