将泛型应用于变量和函数-Swift [英] Applying Generics to Variables and Functions - Swift

问题描述

我试图快速使用泛型，以便在Vector3D类中初始化变量.但是，在将协议"Number"分配给我的变量(使其变为Double或Float)后，出现以下错误:

I'm trying to use generics in swift in order to initialise variables within my Vector3D class. However, upon assigning the protocol 'Number' to my variable (to make it either a Double or Float) I get the following error:

协议"Number"只能用作通用约束，因为它 有自我或相关类型要求

Protocol 'Number' can only be used as a generic constraint because it has Self or associated type requirements

public protocol Number {
    func +(l: Self, r: Self) -> Self
}    
extension Double : Number {}
extension Float  : Number {}


class Vector3D: NSObject {

    var xCord: Number
    var yCord: Number
    var zCord: Number


    func Vector3D(x: [Number], y: [Number], z: [Number]) {
        self.xCord = x
        self.yCord = y
        self.zCord = z
    }
}

那么，我的问题是，如何将泛型应用于swift和函数中的变量?

My questions is then, how do you apply generics to variables in swift and in functions?

推荐答案

您无法在Swift中将泛型添加到变量中，如已显示

You can't add generics to variables in Swift as already shown in this answer, but you can add generics to a function like that:

func swapTwoValues<T>(inout a:T, inout b:T){
  let temporaryA = a
  a = b
  b = temporaryA
}

查看Apple文档.

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