[swift-evolution] [Review] SE-0107: UnsafeRawPointer API "initialize(from:forwardToCount:)"

[Xiaodi Wu]

I'm not sure about that. "Initialize backward from x, count y" is
unambiguous as to how initialization starts and iterates (the first
argument), and it is clear that `count` is an end condition dissociated
from anything to do with how initialization starts and iterates.

By contrast, "Initialize from x, backward from y" associates the direction
of movement with y instead of x. Thus, y becomes the start condition (the
end condition being implicitly "to zero"), thus raising the question of
what position x is in relative to the count y.
On Tue, Jul 5, 2016 at 11:10 Andrew Trick <atrick at apple.com> wrote:

>
> On Jul 5, 2016, at 11:05 AM, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:
>
> I don't mind `initialize(from:forwardToCount:)`, but I do have trouble
> with Brent's suggestion of `initialize(from:backwardFromCount:)`. It adds
> ambiguity as to whether the pointer in the first argument points to the 0th
> element or the (count - 1)th element from which initializing is proceeding
> backward, a problem that does not exist with the currently proposed version
> `initializeBackward(from:count:)`. I don't find the symmetry wins
> compelling enough to overcome that additional ambiguity.
>
>
> That’s a good point, but I think both forms are equally ambiguous.
>
> -Andy
>
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