> Le 8 juin 2017 à 05:15, Susan Cheng via swift-evolution
> <[email protected]> a écrit :
>
> Just a thought
>
> if parentheses is important, why the tuples are not?
>
> var tuple1: (Int, Int) = (0, 0)
> var tuple2: ((((Int, Int)))) = (0, 0)
>
> type(of: tuple1) == type(of: tuple2) // true
>
> var void: ((((((())))))) = ()
>
> type(of: void) == type(of: Void()) // true
I think is is because Swift doesn't have tuples with a single value: those
parenthesis are just parenthesis around an expression:
let a = 1 + 2
let b = (1 + 2)
let c = (1 + 2) * 3
let d = ((1 + 2)) * 3
Many languages behave like that, Swift is no exception.
It also allows some fancy/legacy/foreign programming styles :-)
// C-style if
if (a && b) {
...
}
// "return function"
return(a && b)
Languages that have single-valued tuples need a special syntax so that they are
distinguished from parenthesised expressions. In Python, this is a trailing
comma:
1 # 1
(1) # 1
(1,) # (1,)
Swift currently disallows trailing commas inside parenthesis.
Gwendal
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