PATs-Dynamic-Dispatch-3.swift

protocol Animal {
    
    var name: String { get }
    func walk()
    
    associatedtype FoodType
    func eat(food: FoodType)
}

class Cow: Animal {

    let name: String
    
    init(withName name: String) {
        self.name = name
    }
    
    func walk() {
        print("\(name) is walking in the farm.")
    }
    
    // Cow should eat grass
    func eat(food: Grass) {
        print("\(name) eat \(food.foodName)")
    }
}

class Tiger: Animal {
    
    let name: String
    
    init(withName name: String) {
        self.name = name
    }
    
    func walk() {
        print("\(name) is walking in the jungle.")
    }
    
    // Tiger should eat meat
    func eat(food: Meat) {
        print("\(name) eat \(food.foodName)")
    }
}

// Food for cow
struct Grass {
    let foodName = "Grass"
}

// Food for tiger
struct Meat {
    let foodName = "Meat"
}

// Create concrete of Animal
let myTiger = Tiger(withName: "My Tiger")
let myCow = Cow(withName: "My Cow")
let animalArray: [Animal] = [myTiger, myCow] // error: Protocol 'Animal' can only be used as a generic constraint because it has Self or associated type requirements