DIProductExample

DIProductExample.swift

typealias Price = Double
struct Product {
    let name: String
    let price: Price
}

struct Coupon {
    let code: String
    let percentage: Double
}

struct Cart {
    var products: [Product] = [] {
        didSet {
             totalPrice = products.map{$0.price}.reduce(0.0){ $0 + $1 }
        }
    }
    private(set) var totalPrice: Price = 0.0

    mutating func apply(_ coupon: Coupon) {
        totalPrice -= totalPrice * (coupon.percentage / 100)
    }
    mutating func add(_ product: Product) {
        products.append(product)
    }
}