Design pattern學習 – 4 (Simple Factory簡單工廠模式)

定義一個簡單工廠，傳入不同的參數取得不同的類別物件。

Simple Factory其實違反了SOLID中的open/close principle，因為每次想要擴充可產生的object種類，都要ㄧ再修改Simple Factory中負責產生object的switch case。

	// Product and Concrete Product
	protocol Adventurer {
	func getType() -> String
	}

	class Archer: Adventurer {
	func getType() -> String {
	print("I'm an archer")
	return String(describing: Archer.self)
	}
	}

	class Warrior: Adventurer {
	func getType() -> String {
	print("I'm a warrior")
	return String(describing: Warrior.self)
	}
	}

	// Simple Factory
	class TrainingCamp {
	static func trainAdventurer(type: String) -> Adventurer? {
	switch type {
	case "archer":
	return Archer()
	case "warrior":
	return Warrior()
	default:
	return nil
	}
	}
	}

	let archer = TrainingCamp.trainAdventurer(type: "archer")
	let warrior = TrainingCamp.trainAdventurer(type: "warrior")

	assert(archer is Archer, "Didn't get the archer object!!")
	assert(warrior is Warrior, "Didn't get the warrior object!!")

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