I think switch treats (x,y) as two variables instead of a tuple. So it
prohibits int_1_1 as it looks like one value only at the first glance.
Below two expressions will work.
case (int_1_1.0,int_1_1.1): // <<<<
case let foo where foo == int_1_1: // <<<<
That why you can use something like
case (_, 10)
Zhaoxin
On Tue, Jul 5, 2016 at 5:56 AM, Neil Faiman via swift-users <
swift-users@swift.org> wrote:
> (Resending — this didn’t get any responses when I sent it a month ago.)
>
> Swift 2.2 in Xcode 7.3.1.
>
> Apparently you cannot use a named tuple constant as an expression pattern
> in a case label.
>
> func test(x: Int, y: Int) -> Int {
> let int_1 = 1
> switch x {
> case 0:
> return 0
> case int_1:
> return 1
> default:
> break
> }
>
> let int_1_1: (Int, Int) = (1, 1)
> switch (x, y) {
> case (0, 0):
> return 0
> case int_1_1: // <<<<
> return 1
> default:
> return -1
> }
> }
>
> error: expression pattern of type '(Int, Int)' cannot match values of type
> '(Int, Int)'
> case int_1_1:
> ^~~~~~~
>
> The error message is particularly amusing.
>
> - Neil Faiman
> _______________________________________________
> swift-users mailing list
> swift-users@swift.org
> https://lists.swift.org/mailman/listinfo/swift-users
>
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