I love the idea of a leading and trailing backslash. It makes it much easier to read, and handles the "but what if I want to access a property of a KeyPath?" case really well.
For example, these two are clearly distinct: let x = \Person.mother.age\.valueType let y = \Person.mother.age.valueType\ I'm not sure why an 'age' object would have a 'valueType' property, but this variant makes it easy to handle. Even in cases where no disambiguation is required, having the trailing backslash makes it much easier to read as I'm scanning through code. -BJ >>> On Apr 5, 2017, at 9:13 PM, Xiaodi Wu via swift-evolution >>> <[email protected]> wrote: >>> >>> On Wed, Apr 5, 2017 at 9:21 PM, Ricardo Parada via swift-evolution >>> <[email protected]> wrote: >>> >>> On Apr 5, 2017, at 9:41 PM, Brent Royal-Gordon via swift-evolution >>> <[email protected]> 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) > > That's an interesting point. While `\` alone seems acceptable, I think it's > unfortunate that we'll have `(\...)` and `\(...)` both in the language. > Can we maybe consider instead: > > let firstFriendsNameKeyPath = \Person.friends[0].name\ > > It is also worth mentioning that, with the sigil, the `keyPath` label may not > be so necessary: > > print(luke[\.friends[0].name]) > // or, if the suggestion above is accepted > print(luke[\.friends[0].name\]) > > _______________________________________________ > swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution
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