Design pattern – Observer pattern

哪種Design pattern(Creational/Structural/Behavioural):

Behavioural pattern

目的:

處理一對多的物件關係


	class Subject {
	var list: [Adventurer] = []
	func add(adventurer: Adventurer) {
	list.append(adventurer)
	}
	func remove(adventurer: Adventurer) {
	if let index = list.firstIndex(where: { $0 == adventurer}) {
	list.remove(at: index)
	}
	}
	func sendQuestions(question: String) {}
	}

	class Association: Subject {
	override func sendQuestions(question: String) {
	print("send questions")
	list.forEach { $0.getQuestions(question: question) }
	}
	}

	class Adventurer: Hashable {
	var id: String
	var name: String
	init(id: String, name: String) {
	self.id = id
	self.name = name
	}

	func hash(into hasher: inout Hasher) {
	hasher.combine(id)
	hasher.combine(name)
	}

	static func == (lhs: Adventurer, rhs: Adventurer) -> Bool {
	return lhs.id == rhs.id
	}

	func getQuestions(question: String) {}
	}

	class Bard: Adventurer {
	override func getQuestions(question: String) {
	print("Bard get question")
	}
	}

	class Gunman: Adventurer {
	override func getQuestions(question: String) {
	print("Gunman get question")
	}
	}

	class Lancer: Adventurer {
	override func getQuestions(question: String) {
	print("Lancer get question")
	}
	}


	let lancer = Lancer(id: UUID().uuidString, name: "lancer")
	let bard = Bard(id: UUID().uuidString, name: "bard")
	let gunman = Gunman(id: UUID().uuidString, name: "gunman")
	let association = Association()
	association.add(adventurer: lancer)
	association.add(adventurer: bard)
	association.add(adventurer: gunman)
	association.sendQuestions(question: "ChatGPT can substitute the work of people 😀")

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