[swift-evolution] [Review #2] SE-0161: Smart KeyPaths: Better Key-Value Coding for Swift

Ricardo Parada rparada at mac.com
Wed Apr 5 21:21:47 CDT 2017

> On Apr 5, 2017, at 9:41 PM, Brent Royal-Gordon via swift-evolution <swift-evolution at swift.org> wrote:
> It's worth noting that, if you write `\Person.name.valueType`, this syntax is ambiguous—it could mean "make a key path for the `valueType` property on `name` property of `Person`", or it could mean "make a key path for the `name` property of `Person`, then access the key path's `valueType` property". We can solve this by always interpreting it as the former and requiring parentheses for the latter—that is, `(\Person.name).valueType`—but I thought it was worth calling out explicitly.

Good point. 

 I'm thinking about the hypothetical code examples from previous emails:

   let isPuppyQualifier = \Pet.type == .dog && \Pet.age < 12
   let familyQualifier = (\Family.pets).contains(where: isPuppyQualifier)
   let familiesWithPuppies = Family.fetch(editingContext, familyQualifier)

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