Well, it turns out, I was testing it on already established values. The first
of the following two examples works but the second does not.
switch (true, y: false) {
case (true, y: false): print("tf")
default: print("nope")
}
let testTuple2 = (true, false)
switch testTuple2 {
// error: tuple pattern element label 'y' must be '_'
case (true, y: false): print("tf")
default: print("nope")
}
I think this gets a 95% Emily Litella
(https://en.wikipedia.org/wiki/Emily_Litella
<https://en.wikipedia.org/wiki/Emily_Litella>). "Nevermind."
And thanks, Tony,
-- E
> On Jan 1, 2017, at 8:49 PM, Tony Allevato <[email protected]> wrote:
>
> The "after" example you posted seems to work already in Swift today. Is there
> something I'm missing?
>
>
> On Sun, Jan 1, 2017 at 7:35 PM David Sweeris via swift-evolution
> <[email protected] <mailto:[email protected]>> wrote:
>
>
> Sent from my iPhone
>
> On Jan 1, 2017, at 19:25, Erica Sadun via swift-evolution
> <[email protected] <mailto:[email protected]>> wrote:
>
>> Was helping a friend with some code and got inspired. I decided to throw
>> this on list to see if there's any traction.
>>
>> Idea: Introduce optional argument labels to tuples in switch statements
>>
>> Motivation: Cases can be less readable when pattern matching tuples.
>> Semantically sugared, optional argument labels could increase readability
>> for complex `switch` statements by incorporating roles into cases.
>>
>> Here's an example before:
>>
>> fileprivate func chargeState(for battery: BatteryService)
>> -> ChargeState
>> {
>> switch (battery.state, battery.isCalculating) {
>> case (.isACPowered, true):
>> return .calculating(isDischarging: false)
>> case (.isACPowered, _) where battery.isCharging:
>> return .charging
>> case (.isACPowered, _):
>> return .acPower
>> case (_, true):
>> return .calculating(isDischarging: true)
>> default:
>> return .batteryPower
>> }
>> }
>>
>> and after:
>>
>> fileprivate func chargeState(for battery: BatteryService)
>> -> ChargeState
>> {
>> switch (battery.state, calculating: battery.isCalculating) {
>> case (.isACPowered, calculating: true):
>> return .calculating(isDischarging: false)
>> case (.isACPowered, _) where battery.isCharging:
>> return .charging
>> case (.isACPowered, _):
>> return .acPower
>> case (_, calculating: true):
>> return .calculating(isDischarging: true)
>> default:
>> return .batteryPower
>> }
>> }
>>
>> It's a pretty minor change, and I could see it being added to allow case
>> statements to be more readable with a minimal change to the compiler. I also
>> have a back-burnered proposal I intend to introduce in Phase 2 that would
>> introduce Boolean raw value enumerations for flags.
>>
>> Thoughts?
>
> I can't think of a reason not to do that... +1
>
> - Dave Sweeris
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