AnyPokemon

Pokemon.swift

protocol Pokemon {
    typealias PokemonType
    func attack(move: PokemonType)
}

class Pikachu: Pokemon {
    func attack(move: Int) {
        print("pika")
    }
}

class Hitokage: Pokemon {
    func attack(move: Double) {
        print("fire")
    }
}

class AnyPokemon<PokemonType>: Pokemon {
    let _attack: PokemonType -> Void
    required init<U: Pokemon where U.PokemonType == PokemonType>(_ pokemon: U) {
        _attack = pokemon.attack
    }
    func attack(move: PokemonType) {
        _attack(move)
    }
}

let pika = AnyPokemon(Pikachu())
let hito = AnyPokemon(Hitokage())
pika.attack(3)
hito.attack(3.0)