如何在元组上定义后缀运算符？

Question

我有以下代码：

postfix operator ^^^
public postfix func ^^^(lhs: Int) -> Int {
    return 0
}

public postfix func ^^^<T>(lhs: (T, T)) -> [T] {
    return [lhs.0, lhs.1]
}

func go() {
    1^^^ // this works
    (0, 0)^^^ // error: Unary operator '^^^' cannot be applied to an operand of type '(Int, Int)'
}

为此我得到了错误，Unary operator '^^^' cannot be applied to an operand of type '(Int, Int)'。有什么解决办法吗？

Answer 1

这是一个已知错误，比较 Swift 论坛中的 Prefix and postfix operators not working for tuple types 和 SR-294 Strange errors for unary prefix operator with tuple arg.

已为 Swift 5 修复，以下在 Xcode 10.2 beta 4 中编译和运行：

postfix operator ^^^

public postfix func ^^^<T>(lhs: (T, T)) -> [T] {
    return [lhs.0, lhs.1]
}

let x = (0, 0)^^^
print(x) // [0, 0]

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