Array의 원소들을 개별 변수로 분해하는 함수.

destruct.swift

enum DesctructError: ErrorProtocol {
    case outOfIndex(String)
}

func desctruct<A> (array: [A]) throws -> (A, A) {
    guard array.count > 1 else {
        throw DesctructError.outOfIndex("the array doesn't have enough elements.")
    }
    return (array[0], array[1])
}

func desctruct<A> (array: [A]) throws -> (A, A, A) {
    guard array.count > 2 else {
        throw DesctructError.outOfIndex("the array doesn't have enough elements.")
    }
    return (array[0], array[1], array[2])
}

func desctruct<A> (array: [A]) throws -> (A, A, A, A) {
    guard array.count > 2 else {
        throw DesctructError.outOfIndex("the array doesn't have enough elements.")
    }
    return (array[0], array[1], array[2], array[3])
}


let str = "1 2 3 4"
let (x, y, z) = try! desctruct(array:str.characters.split(separator:" ").map{ Int(String($0))! })
print(x, y, z)