[swift-evolution] Require parameter names for ENUM Associated Types?

[Adrian Zubarev]

I already said it, I don’t want to wrap my types into optionals when there is no need for that.

Plus what’s the need of default values in associated enum cases anyways? Just assume for a second that we could overload enum cases:

enum MyEnum {
   case a(Int)
   case a(Int, b: Int = 42)
}

let myEnumValue = MyEnum.a(0) // What will this produce? Or should we write `MyEnum.a(0, b:)` which is ugly from my point of view
However I see where this might work, but again, what’s the use case here?

enum MyEnum {
   case a(Int)
   case a(Int = 42, b: Int)
}

let a1 = MyEnum.a(0)
let a2 = MyEnum.a(b: 0)  


-- 
Adrian Zubarev
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Am 29. November 2016 um 17:19:16, Tony Allevato (allevato at google.com) schrieb:

I suppose I'm not seeing why it's important to exclude the associated values from pattern matching. What do you gain except saving a few characters? What you're suggesting doesn't strike me as a significant improvement over this:

```
case javascript(String, scope: Document?)
...

switch self {
  case .javascript(_, scope: .none): return 0x0D
  case . return 0x0F   // or case .javascript(_, scope: .some), if you want to be explicit about the distinction between the two cases
}
```


On Tue, Nov 29, 2016 at 8:12 AM Adrian Zubarev <adrian.zubarev at devandartist.com> wrote:
As I said before, the associated values can be excluded for pattern matching. I believe this way you can check against the enum case without producing any copy of the associated types right?!

var _kind: Byte {
          
    switch self {
              
    …
    case .javaScript:       return 0x0D
    case .scopedJavaScript: return 0x0F
    …
    }
}
Assume we could overload the values by including additional labels to the enum case.

case javaScript(String)
case javaScript(String, scope: Document) // or more swifty `javascript(String, withScope: Document)`
Now I could check the case like this to solve the ambiguity.

switch self {
              
…
case .javaScript:               return 0x0D
case .javaScript(_:withScope:): return 0x0F
…
}
Plus I don’t want to wrap values in optionals when there is no need for that.



-- 
Adrian Zubarev
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Am 29. November 2016 um 17:03:12, Tony Allevato (allevato at google.com) schrieb:

Why not:

```
case javascript(String, scope: Document?)
```

Your desired scenario looks like it's conceptually expressing that Document is optional, so why not use the type to codify that?

On Tue, Nov 29, 2016 at 7:59 AM Adrian Zubarev via swift-evolution <swift-evolution at swift.org> wrote:
Hmm, I feel like default values wouldn’t work with overloaded enum cases.

In my own project I have something like this:

case javaScript(String)
case scopedJavaScript(String, scope: Document)

// But I'd like it to be:
case javaScript(String)
case javaScript(String, scope: Document)


-- 
Adrian Zubarev
Sent with Airmail

Am 29. November 2016 um 16:55:52, Charles Srstka (cocoadev at charlessoft.com) schrieb:

On Nov 29, 2016, at 9:52 AM, Adrian Zubarev via swift-evolution <swift-evolution at swift.org> wrote:

I just showed a direction of what could be possible. 

Personally I think it would be enough if we had this:

enum MyEnum {
        
    case a
    case b(Int)
    case b(Int, string: String)
}     
Where .b can be overloaded by it’s associated types.

Or default values:

enum MyEnum {
case a
case b(Int, string: String = “SomeDefault”)
}

Charles

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