具有静态常量的字符串类型vs struct的枚举

问题描述

似乎当需要使用（字符串类型的）枚举时，也可以使用带有静态字段的struct来实现。

It seems like when the need to use enum (of string type) arise, it can also be achieved using struct using static fields.

eg

enum Test: String {
  case TestCase1
  case TestCase2
  case TestCase3
}

或

struct Test {
  static let TestCase1 = "TestCase1"
  static let TestCase2 = "TestCase2"
  static let TestCase3 = "TestCase3"
}

何时使用枚举方法优于其他方法，反之亦然？

When is the enum approach preferred over the other, or vice versa?

推荐答案

它们都是完全可行的。

我以前认为枚举方法不太灵活，因为您必须明确询问$原始值，以便到达基础字符串，但我不再这么认为，因为有一些方法可以扩展诸如NSUserDefaults之类的类，以自动 提取原始值。

I used to argue that the enum approach was less flexible because you had to ask explicitly for the raw value in order to reach the underlying string, but I no longer think that, because there are ways to extend classes such as NSUserDefaults to pull out the raw value automatically.

所以我现在更多很有可能遵循以下明显的经验法则：如果这只是某些常量的美化命名空间，则具有静态成员的结构似乎最简单。枚举是用于 switch 的，即某种东西必须确切地存在于几种可能的状态中。

So now I'm more likely to follow this more obvious rule of thumb: if this is just a glorified namespace for some constants, a struct with static members seems simplest. An enum is for a switch, i.e. something that needs to exist in exactly one of several possible states.

但我什至不关注该规则始终如一，因为带有原始值的枚举具有结构所没有的优点。例如，如果您有一个带有原始值的枚举，则可以非常容易地从原始值获取对应的枚举大小写（通过调用 init（rawValue：）） 。使用结构并不容易。

But I don't even follow that rule consistently, because the enum with the raw value has advantages that the struct does not. For example, if you have an enum with a raw value, then you can get from the raw value to the corresponding enum case really easily (by calling init(rawValue:)). That's not so easy with a struct.

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