swift - 符合 Swift 3.1 中的 Strideable 协议(protocol)

Question

我正在经历转换为 Swift 3.1 的绝对喜悦我遇到了 Strideable 协议(protocol)的问题。以下代码无法编译；唯一的错误消息是类型“Segment”不符合 Strideable 协议(protocol)(也不符合 _Strideable)。四处搜索，我发现了一堆关于关联类型和嵌套类型的东西，但没有什么特别的。

struct segment: Equatable, Comparable, Hashable, Strideable {
var segTurn: Int
var segSegment: Int
typealias Stride = Int

init() {
    segTurn = 0
    segSegment = 12
}

init(segment: Int, turn: Int) {
    segTurn = turn
    segSegment = segment
}

var hashValue: Int {
    get {
        return "\(self.segTurn),\(self.segSegment)".hashValue
    }
}

var description: String {
    if segTurn == 0 && segSegment == 12 {
        return "Start of Combat Segment 12"
    }
    return "Turn: \(self.segTurn) Segment: \(self.segSegment)"
}

static func successor() -> segment {
    return self + 1
}

static func advanced(by n: Int) -> segment {
    return self + n
}

static func distance(to other: segment) -> Int {
    return other - self
}

static postfix func ++(theSeg:inout segment) -> segment {
    theSeg = theSeg + 1
    return theSeg
}

static func +(lhs:segment, rhs:Int) -> segment {
    var intSeg = lhs.segSegment + rhs
    var intTurn = lhs.segTurn
    while intSeg > 12 {
        intTurn += 1
        intSeg = intSeg - 12
    }
    while intSeg < 1 {
        intTurn -= 1
        intSeg = intSeg + 12
    }

    return segment(segment: intSeg, turn: intTurn)
}

static func -(lhs:segment, rhs:Int) -> segment {
    var intSeg = lhs.segSegment - rhs
    var intTurn = lhs.segTurn
    while intSeg > 12 {
        intTurn += 1
        intSeg = intSeg - 12
    }
    while intSeg < 1 {
        intTurn -= 1
        intSeg = intSeg + 12
    }

    return segment(segment: intSeg, turn: intTurn)
}

static func ==(lhs:segment, rhs:segment) -> Bool {
    let areEqual = lhs.segTurn == rhs.segTurn &&
        lhs.segSegment == rhs.segSegment

    return areEqual
}

static func <(lhs:segment, rhs:segment) -> Bool {
    var isLessThan = false
    if lhs.segTurn < rhs.segTurn {
        isLessThan = true
    } else if lhs.segTurn == rhs.segTurn && lhs.segSegment < rhs.segSegment {
        isLessThan = true
    }
    return isLessThan

}

Answer 1

以下是您需要修改以使其工作的内容:

1. 从 Segment 中的所有函数中删除静态关键字。 (将它们保留为实例方法)
   
2. 将所有运算符函数移到段结构定义之外。

然后您的代码将如下所示，并且在 Swift 3.1 中编译时不会出现错误/警告:

struct Segment: Equatable, Comparable, Hashable, Strideable {
    var segTurn: Int
    var segSegment: Int
    typealias Stride = Int

    init() {
        segTurn = 0
        segSegment = 12
    }

    init(segment: Int, turn: Int) {
        segTurn = turn
        segSegment = segment
    }

    var hashValue: Int {
        get {
            return "\(self.segTurn),\(self.segSegment)".hashValue
        }
    }

    var description: String {
        if segTurn == 0 && segSegment == 12 {
            return "Start of Combat Segment 12"
        }
        return "Turn: \(self.segTurn) Segment: \(self.segSegment)"
    }

    func successor() -> Segment {
        return self + 1
    }

    func advanced(by n: Int) -> Segment {
        return self + n
    }

    func distance(to other: Segment) -> Int {
        return other - self
    }
}

postfix func ++(theSeg:inout Segment) -> Segment {
    theSeg = theSeg + 1
    return theSeg
}

func +(lhs:Segment, rhs:Int) -> Segment {
    var intSeg = lhs.segSegment + rhs
    var intTurn = lhs.segTurn
    while intSeg > 12 {
        intTurn += 1
        intSeg = intSeg - 12
    }
    while intSeg < 1 {
        intTurn -= 1
        intSeg = intSeg + 12
    }

    return Segment(segment: intSeg, turn: intTurn)
}

func -(lhs:Segment, rhs:Int) -> Segment {
    var intSeg = lhs.segSegment - rhs
    var intTurn = lhs.segTurn
    while intSeg > 12 {
        intTurn += 1
        intSeg = intSeg - 12
    }
    while intSeg < 1 {
        intTurn -= 1
        intSeg = intSeg + 12
    }

    return Segment(segment: intSeg, turn: intTurn)
}

func ==(lhs:Segment, rhs:Segment) -> Bool {
    let areEqual = lhs.segTurn == rhs.segTurn &&
        lhs.segSegment == rhs.segSegment

    return areEqual
}

func <(lhs:Segment, rhs:Segment) -> Bool {
    var isLessThan = false
    if lhs.segTurn < rhs.segTurn {
        isLessThan = true
    } else if lhs.segTurn == rhs.segTurn && lhs.segSegment < rhs.segSegment {
        isLessThan = true
    }
    return isLessThan
}