Question

我正在尝试拨打struct我使用的协议扩展方法制作的public struct AdjacentDifferenceArrayGenerator<T: Strideable where T.Stride == T>: GeneratorType { private var array: [T] public init<U: SequenceType where U.Generator.Element == T>(source: U) { self.array = source.adjacentDifference() } public mutating func next() -> [T]? { guard !array.isEmpty else { return nil } defer { self.array = self.array.adjacentDifference() } return self.array } } public extension SequenceType where Generator.Element: Strideable { public func adjacentDifference() -> [Self.Generator.Element.Stride] { var result: [Self.Generator.Element.Stride] = [] var generator = AdjacentDifferenceGenerator(generator: self.generate()) while let difference = generator.next() { result.append(difference) } return result } } public extension SequenceType where Generator.Element: Strideable, Generator.Element.Stride: Strideable, Generator.Element.Stride.Stride == Generator.Element.Stride { public func pyramidOfAdjacentDifferences() -> [[Self.Generator.Element.Stride]] { var result: [[Self.Generator.Element.Stride]] = [] var array = self.adjacentDifference() while !array.isEmpty { result.append(array) array = array.adjacentDifference() } //var generator = AdjacentDifferenceArrayGenerator(source: self) //while let differences = generator.next() { //result.append(differences) //} return result }：

AdjacentDifferenceArrayGenerator

在替代算法之后，在末尾附近评论的四行尝试使用与第一个扩展中的方法相同的算法。当我取消注释第一行时，游标等待“{{1}}”并说：“无法为类型'AdjacentDifferenceArrayGenerator＆lt; _＆gt;'调用初始化程序带有'（source：Self）'类型的参数列表“尽管它在代码中没有大写，但最后一个”Self“在错误消息中大写。在类型和初始化程序参数之间添加显式模板括号没有帮助。有什么想法吗？

Answer 1

我通过取消第一次迭代来解决这个问题：

public extension SequenceType where Generator.Element: Strideable, Generator.Element.Stride: Strideable, Generator.Element.Stride.Stride == Generator.Element.Stride {
    public func pyramidOfAdjacentDifferences() -> [[Self.Generator.Element.Stride]] {
        var result = [self.adjacentDifference()]
        if result.first!.isEmpty {
            return []
        }

        var generator = AdjacentDifferenceArrayGenerator(source: result.first!)
        while let differences = generator.next() {
            result.append(differences)
        }
        return result
    }
}

我必须测试第一次迭代结果是否合法，因为将其从循环中取出意味着我丢失了自动检查。我不知道是否使用“self”是问题，或者是使用通用序列而不是确定数组是问题所在。这里还需要帮助....

无法从Swift中的协议扩展调用通用初始化程序

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