if案例的补充 [英] complementery of an if case

问题描述

你会怎么写这个：

if case .SomeEnum(3) = enumType where myInt == 3 {
   //I don't need this case
} else {
   //This is the case I need
}

我知道我可以使用后卫：

guard case .SomeEnum(3) = enumType where myInt == 3 else {
    //This is the case I need
}

但我不认为它是干净的，因为它实际上不是一个功能无法完成的情况。此外， guard 希望我从该函数返回。

but I don't think it is clean, since it is not really a case in which the function is not able to finish. Also, guard expects me to return from the function.

还有其他选择吗？

推荐答案

你不能否定一个模式（据我所知），你的第一个解决方案
使用 if / else 对我来说很好，代码的意图显然是
可见。

You cannot negate a pattern (as far as I know), and your first solution using if/else looks fine to me, the intention of the code is clearly visible.

一个switch语句可以替代：

A switch statement would be an alternative:

switch enumType {
case .SomeEnum(3) where myInt == 3:
    break  // I don't need this case
default:
    // This is the case I need
    // ...
}

关于你的评论

此外，警卫希望我从函数。

Also, guard expects me to return from the function.

并非完全正确。您应该离开当前范围。
所以这将编译并按预期工作：

that is not entirely true. You are expected to leave the current scope. So this would compile and work as expected:

repeat {
    guard case .SomeEnum(3) = enumType where myInt == 3 else {
        // This is the case I need
        // ...
        break
    }
} while false

但我不认为这是一个更好的解决方案。

but I would not consider that a better solution.

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