unownedFunc.swift

//: Playground - noun: a place where people can play

import UIKit

func unownedFunc<T : AnyObject>(target: T, method: (T) -> () -> ()) -> () -> () {
    return { [unowned target] in return method(target)() }
}
func unownedFunc<T : AnyObject, R>(target: T, method: (T) -> () -> R) -> () -> R {
    return { [unowned target] in return method(target)() }
}
func unownedFunc<T : AnyObject, A>(target: T, method: (T) -> (A) -> ()) -> (A) -> () {
    return { [unowned target] a in return method(target)(a) }
}
func unownedFunc<T : AnyObject, R, A>(target: T, method: (T) -> (A) -> R) -> (A) -> R {
    return { [unowned target] a in return method(target)(a) }
}
func unownedFunc<T : AnyObject, A, B>(target: T, method: (T) -> (A, B) -> ()) -> (A, B) -> () {
    return { [unowned target] a, b in return method(target)(a, b) }
}
func unownedFunc<T : AnyObject, R, A, B>(target: T, method: (T) -> (A, B) -> R) -> (A, B) -> R {
    return { [unowned target] a, b in return method(target)(a, b) }
}
func unownedFunc<T : AnyObject, A, B, C>(target: T, method: (T) -> (A, B, C) -> ()) -> (A, B, C) -> () {
    return { [unowned target] a, b, c in return method(target)(a, b, c) }
}
func unownedFunc<T : AnyObject, R, A, B, C>(target: T, method: (T) -> (A, B, C) -> R) -> (A, B, C) -> R {
    return { [unowned target] a, b, c in return method(target)(a, b, c) }
}
func unownedFunc<T : AnyObject, A, B, C, D>(target: T, method: (T) -> (A, B, C, D) -> ()) -> (A, B, C, D) -> () {
    return { [unowned target] a, b, c, d in return method(target)(a, b, c, d) }
}
func unownedFunc<T : AnyObject, R, A, B, C, D>(target: T, method: (T) -> (A, B, C, D) -> R) -> (A, B, C, D) -> R {
    return { [unowned target] a, b, c, d in return method(target)(a, b, c, d) }
}
func unownedFunc<T : AnyObject, A, B, C, D, E>(target: T, method: (T) -> (A, B, C, D, E) -> ()) -> (A, B, C, D, E) -> () {
    return { [unowned target] a, b, c, d, e in return method(target)(a, b, c, d, e) }
}
func unownedFunc<T : AnyObject, R, A, B, C, D, E>(target: T, method: (T) -> (A, B, C, D, E) -> R) -> (A, B, C, D, E) -> R {
    return { [unowned target] a, b, c, d, e in return method(target)(a, b, c, d, e) }
}

class Greeter {
    func greet(person: String) -> String {
        return "Hello, \(person)!"
    }
}


let greeter = Greeter()
let people = ["Rhys", "Tom"]

// `greeter` is not retained
print(people.map(unownedFunc(greeter, method: Greeter.greet)))

// Output:
// ["Hello, Rhys!", "Hello, Tom!"]