[swift-evolution] Proposal: Tuple Convertible

[John McCall]

> On Dec 6, 2015, at 4:07 PM, Nikolai Vazquez via swift-evolution <swift-evolution at swift.org> wrote:
> I was thinking it could work for variables that are already tuples but then that goes against Swift's strict typing. So really it should only be for tuple literals.
> 

I think this is an interesting idea, but I believe it’s not actually expressible in the current generics system without hard-coding the protocol to just 2-tuples.

John.

> 
> On Sun, Dec 6, 2015, 7:01 PM Stephen Celis <stephen.celis at gmail.com <mailto:stephen.celis at gmail.com>> wrote:
> Do you mean a TupleLiteralConvertible? I’m also in favor of a ClosureLiteralConvertible (or FunctionLiteralConvertible).
> 
> Stephen
> 
> 
>> On Dec 6, 2015, at 6:40 PM, Nikolai Vazquez via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 
> 
>> When working with points, I’ll sometimes make a typealias to an integer tuple:
>> 
>> typealias Point = (x: Int, y: Int)
>> However, if I want to add extended functionality to my Point type, I would have to change it to a struct, removing the ability to create one on the fly with a tuple.
>> 
>> I’m proposing a TupleConvertible protocol that allows initialization from a tuple directly.
>> 
>> struct Point: TupleConvertible {
>> 
>>     var x, y: Int
>> 
>>     init(x: Int, y: Int) {
>>         self.x = x
>>         self.y = y
>>     }
>> 
>>     init(tuple: (x: Int, y: Int)) {
>>         self.init(x: tuple.x, y: tuple.y)
>>     }
>> 
>> }
>> This would make it very easy to create new Point instances.
>> 
>> let somePoint: Point = (50, 120)
>> let otherPoint = Point(x: 50, y: 120)
> 
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