> Date: Fri, 31 Mar 2017 04:33:43 -0700
> From: Brent Royal-Gordon <[email protected]>
> To: Haravikk <[email protected]>
> Cc: Haravikk via swift-evolution <[email protected]>
> Subject: Re: [swift-evolution] Smart KeyPaths
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset="utf-8"
>
>> On Mar 31, 2017, at 3:07 AM, Haravikk via swift-evolution
>> <[email protected]> wrote:
>>
>> Is it actually in-use or just reserved? Not sure I've ever needed it in the
>> debugger.
>
> Pop into the REPL for a minute:
>
> $ swift
> Welcome to Apple Swift version 3.1 (swiftlang-802.0.41 clang-802.0.36).
> Type :help for assistance.
> 1> "hello"
> $R0: String = "hello"
> 2> $R0
> $R1: String = "hello"
>
> You may not have ever noticed it was there, but it was.
>
>> What about @? It has a certain appropriateness in how it reads for a path
>> like: @Person.friend.lastName
>
> We're already using @ for attributes; I don't think we want to overload its
> meaning.
>
>> Another alternative might be something like an unnamed compiler directive,
>> for example: #(Person.friend.lastName)
>> If you consider the statement to mean "expand this".
>
> The unnamed compiler directive seems like *really* valuable real estate,
> arguably much more so than unresolved-member-on-KeyPath-type is. I think it'd
> be foolish to assign it to anything before we have a macro system designed.
I agree that #() is too valuable to burn at this point.
So… Crazy Thought: Is KeyPath enough of a term-of-art beyond ObjC that we want
to carry it’s semantics directly into Swift even when it conflicts with
established ObjC inter-op? In other words, if we didn’t already know ObjC &
KVO/KVC, does “KeyPath” mean what we mean by it in Swift?
If the issue is the conflict with the current semantics of #keyPath(), what
about something like:
```
let fooProp: Property<Foo, String> = #property(bar.bast)
```
And in the inferred/ambiguous case:
```
let fooProp = #property(bar.bast, of: Foo)
```
It perhaps moves too far from the KeyPath nomenclature, but it reads rather
nicely (IMHO).
—Karim
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