[swift-evolution] [Proposal] Adjusting `inout` Declarations for Type Decoration

Allen Ding allen at snappymob.com
Fri Jan 29 18:14:22 CST 2016

1. Is there some data or real world story to support (1)? I've never had
the same expectations even when first encountering Swift and definitely
less so after reading the documentation, because the concept and syntax for
inout and & is not really profound. And even if I did *pointers!*, I would
figure things out rather quickly because nothing else would work.

(2. I don't have experience with Rust, so there would need to be some
details on why being more Rust like is a good thing :)

On Sat, Jan 30, 2016 at 7:50 AM, Erica Sadun via swift-evolution <
swift-evolution at swift.org> wrote:

> The great advantages are:
> 1. It removes a potentially confusing overlap with C-style expectations.
> People see & and think "POINTERS!", which is not how things work in Swift
> with copy-back.
> (2. It eventually frees up &, so we can have more Rust)
> -- E
> On Jan 29, 2016, at 4:42 PM, Charles Kissinger <crk at akkyra.com> wrote:
> Sorry, I wasn’t clear at all there. I was thinking of the most common case
> where there is either only one parameter or the inout parameter is the
> first one. Then there will typically be no argument label involved at the
> call site. In that case ‘inout’ will be the first word inside the parens at
> the call site (assuming it replaces ‘&’). If it also is kept in its current
> position in function declarations, it will be in that same leading position
> in declarations and (I’m assuming) people will have an easy time
> remembering where to put it.
> When there is a label involved, it is a different story. I was implicitly,
> and probably wrongly, assuming that would be a much less common case in
> practice. A poorly worded, and probably poorly reasoned, argument on my
> part, though I still don’t see any great advantage to replacing ‘&'.
> —CK
> On Jan 29, 2016, at 2:13 PM, Erica Sadun <erica at ericasadun.com> wrote:
> On Jan 29, 2016, at 3:04 PM, Charles Kissinger <crk at akkyra.com> wrote:
> The related idea of replacing ‘&’ with ‘inout’ at the call site seems
> completely contradictory to this proposal. Developers would then have to
> remember that the ‘inout’ goes before the argument at the call site but
> after it in the function definition. That seems like a constant source of
> mis-typings and something that would be viewed as an inconsistency in the
> language. Or do people want to put it after the argument name at the call
> site too? It seems a little like change just for the sake of change, IMO.
> If you have a function
> f(x: Int) {}
> you call it with f(8), and potentially f(x: 8). Even when labeled, the 8
> value is to the right of the colon.
> Now consider
> f(x: inout Int) {}
> you call it with f(&y) or f(inout y), and with a label, you'd call it f(x:
> &y) or f(x: inout y).
> It seems  consistent to me.
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