unwrap.swift

// I find no better version than manually writing unwrap 1...n

func unwrap <T> (first: T?, closure: (T)->()) -> () {
    if let p1 = first {
        closure(p1)
    }
}

func unwrap <T1, T2> (first: T1?, second: T2?, closure: (T1, T2)->()) -> () {
    var unwrappedFirst: T1, unwrappedSecond: T2
    if let x = first  { unwrappedFirst  = x } else { return }
    if let x = second { unwrappedSecond = x } else { return }
    closure(unwrappedFirst, unwrappedSecond)
}

func unwrap <T1, T2, T3> (first: T1?, second: T2?, third: T3?, closure: (T1, T2, T3)->()) -> () {
    var unwrappedFirst: T1, unwrappedSecond: T2, unwrappedThird: T3
    if let x = first  { unwrappedFirst  = x } else { return }
    if let x = second { unwrappedSecond = x } else { return }
    if let x = third  { unwrappedThird  = x } else { return }
    closure(unwrappedFirst, unwrappedSecond, unwrappedThird)
}

func unwrap <T1, T2, T3, T4> (first: T1?, second: T2?, third: T3?, fourth: T4?, closure: (T1, T2, T3, T4)->()) -> () {
    var unwrappedFirst: T1, unwrappedSecond: T2, unwrappedThird: T3, unwrappedFourth: T4
    if let x = first  { unwrappedFirst  = x } else { return }
    if let x = second { unwrappedSecond = x } else { return }
    if let x = third  { unwrappedThird  = x } else { return }
    if let x = fourth { unwrappedFourth = x } else { return }
    closure(unwrappedFirst, unwrappedSecond, unwrappedThird, unwrappedFourth)
}


class A {}
class B {}
class C {}

var a: A? = A()
var b: B? = B()
var c: C? = C()

unwrap(a, b, c) {
    a, b, c in
    let x = (a, b, c)
}