0002-dependency-injection-using-property-wrappers-002.swift

class TaxesCalculator {
    func applyTaxes(to subtotal: Double) -> Double {
        // Some weird taxes logic 😨
        subtotal * 1.21
    }
}

class ProductsCalculator {
    private let taxesCalculator = TaxesCalculator()

    // ...

    func calculateTotal() -> Double {
        let subtotal = products.map({ $0.price }).reduce(0, +)
        return taxesCalculator.applyTaxes(to: subtotal)
    }
}