Swift设计模式之装饰模式

转自

• Swift设计模式

原文

• Design-Patterns-In-Swift

// 装饰模式
// 百度百科：在不必改变原类文件和使用继承的情况下，动态地扩展一个对象的功能。它是通过创建一个包装对象，也就是装饰来包裹真实的对象
// 设计模式分类：结构型模式

/** * 咖啡接口 */
protocol Coffee {
    /** 价格 - returns: 价格 */
    func getCost() -> Double
    /** 原料 - returns: 原料 */
    func getIngredients() -> String
}

/// 简单咖啡实现
class SimpleCoffee: Coffee {
    func getCost() -> Double {
        return 1.0
    }

    func getIngredients() -> String {
        return "Coffee"
    }
}

/// 咖啡装饰接口
class CoffeeDecorator: Coffee {
    private let decoratedCoffee: Coffee
    private let ingredientSeparator: String = ","

    required init(decoratedCoffee: Coffee) {
        self.decoratedCoffee = decoratedCoffee
    }

    func getCost() -> Double {
        return decoratedCoffee.getCost()
    }

    func getIngredients() -> String {
        return decoratedCoffee.getIngredients()
    }
}

/// 牛奶装饰实现
class Milk: CoffeeDecorator {
    required init(decoratedCoffee: Coffee) {
        super.init(decoratedCoffee: decoratedCoffee)
    }

    override func getCost() -> Double {
        return super.getCost() + 0.5
    }

    override func getIngredients() -> String {
        return super.getIngredients() + ingredientSeparator + "Milk"
    }
}

/// whip装饰实现
class WhipCoffee: CoffeeDecorator {
    required init(decoratedCoffee: Coffee) {
        super.init(decoratedCoffee: decoratedCoffee)
    }

    override func getCost() -> Double {
        return super.getCost() + 0.7
    }

    override func getIngredients() -> String {
        return super.getIngredients() + ingredientSeparator + "Whip"
    }
}

var someCoffee: Coffee = SimpleCoffee() // 简单咖啡
print("Cost : (someCoffee.getCost()); Ingredients: (someCoffee.getIngredients())")

var milkCoffee = Milk(decoratedCoffee: someCoffee) // 装饰了牛奶的咖啡
print("Cost : (milkCoffee.getCost()); Ingredients: (milkCoffee.getIngredients())")

var whipCoffee = WhipCoffee(decoratedCoffee: milkCoffee) // 装饰了whip和牛奶的咖啡
print("Cost : (whipCoffee.getCost()); Ingredients: (whipCoffee.getIngredients())")