try_swift_report.swift

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

import Foundation

class Thunder { }
class Fire { }

//genericなprotocol
protocol Pokemon {
    typealias PokemonType //swift2.2ではassociatedTypeって書くんだっけ
    func attack(move:PokemonType) //move=わざ
}

struct Pikachu: Pokemon {
    typealias PokemonType = Thunder
    func attack(move: Thunder) { print("サンダー") }
}

class Raichu: Pokemon {
    typealias PokemonType = Thunder
    func attack(move: Thunder) { print("サンダー") }
}

class Charmander: Pokemon {
    func attack(move: Fire) { print("ファイア") }
}

////////

//雷攻撃
let thunderAttack = Thunder()
//火攻撃
let fireAttack = Fire()

//==こういうのを書きたい(雷属性のポケモン配列に雷攻撃させたい)===
//let pikachu = Pikachu()
//let raichu = Raichu()
//// let pikachu:Pokemon = Pikachu() //これはNG
////ポケモンならなんでも入れられる型のobjが定義できない
//
////genericなprotocol型の配列
//let electricPokemons:[Pokemon] = [pikachu, raichu] //これもNG
//for pokemon in electricPokemons {
//    pokemon.attack(thunderAttack)
//}

//////////

//こう書ける
class AnyPokemon <PokemonType>: Pokemon {
    private let _attack: ((PokemonType) -> Void)
    
    required init<U:Pokemon where U.PokemonType == PokemonType>(_ pokemon: U) {
        _attack = pokemon.attack
    }
    
    func attack(type:PokemonType) {
        return _attack(type)
    }
}

let pikachu = AnyPokemon(Pikachu())
let raichu = AnyPokemon(Raichu())

let electricPokemons:[AnyPokemon<Thunder>] = [pikachu, raichu]
for pokemon in electricPokemons {
    pokemon.attack(thunderAttack)
}