> On Apr 7, 2017, at 12:27 AM, Rick Mann <rm...@latencyzero.com> wrote:
>> On Apr 6, 2017, at 20:37 , John McCall <rjmcc...@apple.com> wrote:
>>
>>> On Apr 6, 2017, at 9:28 PM, Rick Mann via swift-evolution
>>> <swift-evolution@swift.org> wrote:
>>> I tend to dislike the backslash as well, but can't suggest a good
>>> alternative.
>>>
>>> Does any of this allow for operations within the key path? e.g.
>>> Department.employees.@sum.salary?
>>
>> You can express things like this in the feature as proposed using subscripts:
>>
>> extension Collection {
>> subscript<T: Integer>(summing path: KeyPath<Element, T>) -> T {
>> var sum: T = 0
>> for let elt in self {
>> sum += elt[keyPath: path]
>> }
>> return sum
>> }
>> }
>
> I'm just remembering how AppKit/Cocoa lets you do things like this in a very
> expressive way. Your proposal seems a bit cumbersome. Maybe when we have
> custom annotations, they can be extended to use within key paths.
I'm not seriously endorsing this exact spelling. It would be much better to be
able to write something like:
\Department.employees.sum(of: \.salary)
However, since "sum" would presumably be a method on Collection, I think this
would have to be a future extension to the proposal, and the overall thing
might have to be a function rather than a key path because it would no longer
have identity.
Also, I do feel obliged to note that AppKit/Cocoa's "very expressive" way of
doing this is a small number of hard-coded operators, whereas even the
kindof-unfortunate subscript trick would be arbitrarily extensible.
John.
>
> Thanks.
>
>>
>> ...
>>
>> \Department.employees[summing: \.salary]
>>
>> That's not actually a good name for the subscript, but maybe there's one out
>> there.
>>
>> John.
>>
>>>
>>> Also, in this example:
>>>
>>> let firstFriendsNameKeyPath = \Person.friends[0].name
>>> let firstFriend = luke[keyPath: firstFriendsNameKeyPath] // "Han Solo"
>>>
>>> Can't we do without the keyPath: argument name? The compiler knows it's a
>>> keypath, it would be nicer to write
>>>
>>> let firstFriend = luke[firstFriendsNameKeyPath] // "Han Solo"
>>>
>>>> On Apr 5, 2017, at 16:56 , Douglas Gregor via swift-evolution
>>>> <swift-evolution@swift.org> wrote:
>>>>
>>>> Hello Swift community,
>>>>
>>>> The second review of SE-0161 "Smart KeyPaths: Better Key-Value Coding for
>>>> Swift" begins now and runs through April 9, 2017. The revised proposal is
>>>> available here:
>>>>
>>>> https://github.com/apple/swift-evolution/blob/master/proposals/0161-key-paths.md
>>>> The core team’s feedback from the first review of this proposal can be
>>>> viewed at:
>>>>
>>>> https://lists.swift.org/pipermail/swift-evolution-announce/2017-April/000342.html
>>>> Reviews are an important part of the Swift evolution process. All reviews
>>>> should be sent to the swift-evolution mailing list at
>>>>
>>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>>> or, if you would like to keep your feedback private, directly to the
>>>> review manager. When replying, please try to keep the proposal link at the
>>>> top of the message:
>>>>
>>>> Proposal link:
>>>>
>>>> https://github.com/apple/swift-evolution/blob/master/proposals/0161-key-paths.md
>>>> Reply text
>>>> Other replies
>>>> What goes into a review?
>>>>
>>>> The goal of the review process is to improve the proposal under review
>>>> through constructive criticism and, eventually, determine the direction of
>>>> Swift. When writing your review, here are some questions you might want to
>>>> answer in your review:
>>>>
>>>> • What is your evaluation of the proposal?
>>>> • Is the problem being addressed significant enough to warrant a change
>>>> to Swift?
>>>> • Does this proposal fit well with the feel and direction of Swift?
>>>> • If you have used other languages or libraries with a similar feature,
>>>> how do you feel that this proposal compares to those?
>>>> • How much effort did you put into your review? A glance, a quick
>>>> reading, or an in-depth study?
>>>> More information about the Swift evolution process is available at
>>>>
>>>> https://github.com/apple/swift-evolution/blob/master/process.md
>>>> Thank you,
>>>>
>>>> -Doug
>>>>
>>>> Review Manager
>>>>
>>>> _______________________________________________
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>>>
>>>
>>> --
>>> Rick Mann
>>> rm...@latencyzero.com
>>>
>>>
>>> _______________________________________________
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>>> swift-evolution@swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>
>
> --
> Rick Mann
> rm...@latencyzero.com
>
>
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