具有静态常量的字符串类型vs struct的枚举 [英] enum of string type vs struct with static constant

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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