更简洁的方法来嵌套枚举以供Swift中的switch语句访问？ [英] More concise way to nest enums for access by switch statements in Swift?

问题描述

我有一个这样的嵌套枚举，用于描述基本的相对位置：

I have a nested enum like so, for describing basic relative positioning:

  enum Location {
    enum Top {
      case Left
      case Right
      case Center
    }
    enum Bottom {
      case Left
      case Right
      case Center
    }
    enum Left {
      case Top
      case Bottom
      case Center
    }
    enum Right {
      case Top
      case Bottom
      case Center
    }
    enum Center {
      case Center
    }
  }

如果我尝试使用它运行 switch 语句，则所有枚举都不会出现，如果我尝试列出它们，则会出现错误：

If I try to run a switch statement with it, none of the enums show up as possible cases, and if I try to list them I get an error:

func switchOverEnum(enumCase: Location) {
  switch enumCase {
  case .Top:
    print("hey this didn't cause an error whoops no it did")
  }
}

错误为： 在'Location'类型中找不到枚举'Top'。

现在有此问题的版本此处，并根据最有帮助的答案，应该这样完成：

Now there's a version of this question here, and according to the most helpful answer, it should be done like this:

   enum Location {
    enum TopLocations {
      case Left
      case Right
      case Center
    }
    enum BottomLocations {
      case Left
      case Right
      case Center
    }
    enum LeftLocations {
      case Top
      case Bottom
      case Center
    }
    enum RightLocations {
      case Top
      case Bottom
      case Center
    }
    enum CenterLocations {
      case Top
      case Bottom
      case Left
      case Right
      case Center
    }
    case Top(TopLocations)
    case Bottom(BottomLocations)
    case Left(LeftLocations)
    case Right(RightLocations)
    case Center(CenterLocations)
  }

虽然完全可以使用，但似乎有点笨拙，笨拙或不敏捷。这真的是最简洁的方法吗？

Which totally works, but seems a bit clunky, or inelegant, or un-Swift-like. Is this really the most concise way?

推荐答案

我认为用两个枚举和一个元组来更简洁地表达它。在操场上尝试：

I think this would be much more concisely expressed with two enums and a tuple. Try this in a playground:

enum HorizontalPosition {
    case Left
    case Right
    case Center
}

enum VerticalPosition {
    case Top
    case Bottom
    case Center
}

typealias Location = (horizontal: HorizontalPosition, vertical: VerticalPosition)

let aLocation = Location(horizontal: .Left, vertical: .Bottom)

switch aLocation {

case (.Left, .Bottom): print ("left bottom")
case (.Center, .Center): print ("center center")
default: print ("everything else")
}

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