将枚举大小写检查写入不符合Equatable一致性的Bool变量

问题描述

我有一个带有与此相关的值的枚举:

I have an Enum with associated values like this one:

enum SomeState {
    case loggedOut(redirectAfterLogin: Module? = nil)
    case loggedIn
}

现在，在某些情况下，我想精确比较两个状态(例如都已注销，并且重定向目标是否相等)，有时我只想知道它们是否都已注销.我的问题涉及第二种情况:我想检查状态是否已注销并将其写入变量，但是显然我不能实现 Equatable 来解决这个问题忽略参数的一般情况.

Now in some cases I want to compare two states exactly (like are both logged out and also is the redirect target equal) and sometimes I just want to know if they are both logged out. My question regards the second case: I want to check if the state is logged out and write that to a variable, but obviously I can't implement Equatable to just account for the general case ignoring the parameters.

一种实现此目的的方法是在Enum本身上实现计算属性 isLoggedOut ，但是由于这只是一个示例，而我的实际代码要大得多，因此对于我.

One way of achieving this would be to implement a computed property isLoggedOut on the Enum itself, but since this here is just an example and my actual code is much larger, this is not an option for me.

第二种方式(我当前使用的方式)是:

A second way (the one I currently use) is this:

func whatever() {
    if case .loggedOut = self.state {
        self.isLoggedOut = true
    } else {
        self.isLoggedOut = false
    }
}

这行得通，但我宁愿这样写:

This works, but I would rather write something like this:

func whatever() {
    self.isLoggedOut = (case .loggedOut = self.state)
}

我是否遗漏了一些东西，还是真的不可能直接将 if -子句的大小写比较写到变量(或类似的单行解决方案)上?

Am I missing something or is it really not possible to write the case comparison of the if-clause to a variable directly (or some similar one-line-solution)?

推荐答案

您只需要将任何内容更改为计算属性而不是函数，将分配修改为 isLoggedOut 成为 return 语句，您就拥有了 isLoggedOut 属性.

You simply need to change whatever to be a computed property rather than a function, modify the assignments to isLoggedOut to be return statements and you've got your isLoggedOut property.

var isLoggedOut: Bool {
    if case .loggedOut = self.state {
        return true
    } else {
        return false
    }
}

简化的示例代码，其中包含 state 属性的类型也定义了 isLoggedOut 属性:

Simplified example code where the type holding the state property defines the isLoggedOut property as well:

enum SomeState {
    case loggedOut
    case loggedIn
}

struct User {
    var state: SomeState

    var isLoggedOut: Bool {
        if case .loggedOut = self.state {
            return true
        } else {
            return false
        }
    }
}

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