[swift-evolution] ternary operator ?: suggestion
David Waite
david at alkaline-solutions.com
Wed Dec 23 01:22:07 CST 2015
In the case where your input is hashable, you could just do:
let i = [.Red:0xff0000, .Green:0x00ff00, .Blue:0x0000ff][color]
this would mean that color must be a Color and not an Optional<Color> (because of swift 2.x limitations)
-DW
> On Dec 22, 2015, at 8:04 AM, Félix Cloutier via swift-evolution <swift-evolution at swift.org> wrote:
>
> I like the gist of it too, though you seem to introduce both a new keyword and a new syntax. (To be clear, I like the syntax but I'm ambivalent towards reusing switch instead of which.)
>
> My minor suggestions would to avoid braces for things that aren't scopes; that either the comma or the the question mark is redundant in their current position (you need a start delimiter or an end delimiter but you don't need both); and that it needs a way to handle a default case if enumeration isn't exhaustive (I'd do that by returning an optional).
>
>> let i = which color (.Red: 0xff0000, .Green: 0x00ff00, .Blue: 0x0000ff) ?? 0x000000
>
>
> Thinking out loud, once you remove the question marks it really looks like a dictionary literal, so maybe it could even use square brackets to close the gap.
>
>> let i = which color [.Red: 0xff0000, .Green: 0x00ff00, .Blue: 0x0000ff] ?? 0x000000
>
>
> I thought about subscripting a dictionary literal in place:
>
>> [Color.Red: 0xff0000, ...][color] ?? 0x000000
>
>
> but that won't support elaborate pattern matching, and I think that this is a deal breaker for the functional folks.
>
> Félix
>
>> Le 22 déc. 2015 à 09:31:32, Charles Constant <charles at charlesism.com> a écrit :
>>
>> Just goofing on this a little. What if we called it a "which" statement, instead of a "switch" statement? It's a bit cutesy, but not too verbose, and it makes sense if you read it aloud.
>>
>> let i = which color {
>> ? .Red: 0xFF0000,
>> ? .Green: 0x00FF00,
>> ? .Blue: 0x00000FF
>> }
>>
>> let i = which boo {
>> ? true: 1,
>> ? false: 0,
>> ? nil: -1
>> }
>>
>
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