Filtering array of functions Swift

Question

When I filter an Array of Functions to exclude a specific function from the array, the filtered array contains no elements. Any idea of why this is happening?

var array: [()->()] = []

array.append(function1)
array.append(function2)

let function: ()
function = function1()
var filteredArray: [()->()] = []
filteredArray = array.filter { $0() != function }

print(filteredArray.count) // 0

Answer 1

Non-Nominal Types cannot be filtered. This is because they are not equatable:

ie Here are some Non-Nominal Types

• Any
• Tuples - soon to be equatable
• Void aka () aka Empty Tuple
• Functions aka () -> ()

What you could do is create a struct like so:

struct Method: Hashable, Equatable {
    var name: String
    var method: () -> () // or whatever type you want
    init(_ n: String,_ m: @escaping () -> ()) {
        name = n
        method = m
    }

    // Equatable
    static func == (lhs: Method, rhs: Method) -> Bool {
        return lhs.name == rhs.name
    }

    // Hashable
    func hash(into hasher: inout Hasher) {
        hasher.combine(name)
    }
}

So that the name is what checks if methods are equal. But so much for structs .

If you wanted, you could make a similar class instead to keep track of the reference.

---

Example code:

func function1() {print("foo")}
func function2() {print("bar")}

var array: [Method] = []

array.append(Method("One", function1))
array.append(Method("Two", function2))

let function: Method
function = Method("One", function1)
var filteredArray: [Method] = []
filteredArray = array.filter { $0 != function}

print(filteredArray.count) // 1

filteredArray.first?.method() // prints "bar"