hwnn_1_6.swift

struct AnimalReport {
    var animal: Animal?
    func describe() {
        guard let animal = animal else { return }
        print("Animal is called \(animal.name) and is \(animal.age) years old")
    }
}

struct AnimalSelection {
    let animals: [Animal]
    var animalReport: AnimalReport
    mutating func selectAnimal(_ animal: Animal) {
        animalReport.animal = animal
        animalReport.describe()
    }
}

let animals: [Animal] = [
    Dog(name: "Doggy", age: 5),
    Horse(name: "Horsy", age: 7)
]

let b = AnimalReport()
var a = AnimalSelection(animals: animals, animalReport: b)

// Runtime
a.selectAnimal(animals[0])