[swift-evolution] Replace named returns with `out` parameters?

[thislooksfun]

Accidentally sent this offlist (why no 'reply to' header?)

-thislooksfun (tlf)

> On Dec 28, 2016, at 9:52 AM, thislooksfun <thislooksfun at repbot.org> wrote:
> 
> This already basically exists in the form `inout`
> // Define the function
> func position(x: inout Int, y: inout Int) {
>     x = 0
>     y = 0
> }
> 
> // Create the variables you want to assign (they do have to be initialized beforehand)
> var x = 0, y = 0
> // And call it! Remember to prefix with & when using a primitive type (not 100% sure what kinds you don't need to specify that for, but the compiler will tell you).
> position(x: &x, y: &y)
> There is no way to define a variable from the value passed to an `inout` parameter (it does need to go 'in' as well, after all), but other than that it seems to be what you're asking for.
> 
> -thislooksfun (tlf)
> 
> 
>> On Dec 28, 2016, at 5:09 AM, Anton Zhilin via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 
>> Some people on the list wondered, why we have moved from tuples in function parameters, but multiple returns are still implemented using tuples? The following code still compiles:
>> 
>> func position() -> (x: Int, y: Int) {
>>     return (x: 0, y: 0)
>> }
>> 
>> let (y, x) = position()
>> (Maybe it’s a bad example, because naturally we’d use Point struct. Let’s pretend those two parameters don’t make sense as a struct.)
>> 
>> What I want to discuss is if we should introduce out parameters and make them the default for multiple returns for Swift 4. The syntax would look like:
>> 
>> func position(x: out Int, y: out Int) {
>>     x = 0
>>     y = 0
>> }
>> 
>> var y
>> position(x: let x, y: y)
>> out arguments can be any patterns allowed on the left side of assignment, including wildcard pattern and tuple destructuring pattern.
>> 
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>> swift-evolution at swift.org <mailto:swift-evolution at swift.org>
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> 

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