[swift-evolution] [Proposal Idea] dot shorthand for instance members

[Dennis Lysenko]

+1. One important consideration, however, and I would love to see some
input from Chris Lattner or someone else who works on LLVM, is how much it
would complicate the grammar of the language when all possible cases are
considered.

On Fri, Dec 18, 2015, 8:05 AM Matthew Johnson via swift-evolution <
swift-evolution at swift.org> wrote:

>
> On Dec 18, 2015, at 6:52 AM, Al Skipp <al_skipp at fastmail.fm> wrote:
>
> On 18 Dec 2015, at 03:27, Matthew Johnson via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> Swift currently offers dot shorthand for static members of type Self in
> type contexts expecting a value of the type in question.  This is most
> commonly used with enum cases.
>
> Swift does not currently offer shorthand for instance members.
> Introducing a shorthand for instance members would improve clarity and
> readability of code in common cases:
>
> anArray.map{$0.anInstanceMethod()}
>
> becomes:
>
> anArray.map(.anInstanceMethod())
>
> This shorthand would work in typing contexts expecting a single argument
> function.  It would allow abbreviated access to any visible instance
> property getter or instance method on the type of the argument.  Of course
> the return type would need to match the return type expected by the context
> or a type mismatch compiler error would occur.
>
> The readability advantage is arguably small but it does exist.  The
> feature also aligns very well with an existing language feature.
>
> I think it’s an interesting idea and am wondering whether others feel like
> it is something worth pursuing or not.
>
> Matthew
>
>
> I’d be interested to hear peoples thoughts regarding this proposal. I’m
> personally in favour, but perhaps there are potential issues with the
> suggestion?
>
> It’s only a small visual change, but I think it is a syntactic
> improvement. Let’s pretend for a moment that the current syntax was:
> *anArray.map(.anInstanceMethod())*
>
> I’m not sure many people would argue for it to be changed to:
> *anArray.map { $0.anInstanceMethod() }*
>
>
> Thanks Al.  I should have also pointed out that the syntactic advantage is
> a bit greater in other contexts where the braces would not replace
> parentheses:
>
> struct S {
>   var predicate: String -> Bool
> }
>
> var s = S()
> s.predicate = { $0.hasPrefix(“abc”) }
>
> vs
> s.predicate = .hasPrefix(“abc”)
>
> It’s not a super important change, but maybe a low-hanging fruit item that
> can improve clarity and readability.
>
> Matthew
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