9.2.1 الگو Decorator

package main

import "fmt"

// Component Interface
type Coffee interface {
    Cost() float64
    Description() string
}

// Concrete Component - Basic Coffee
type BasicCoffee struct{}

func (b *BasicCoffee) Cost() float64 {
    return 2.00
}

func (b *BasicCoffee) Description() string {
    return "Basic Coffee"
}

// Decorator Base
type CoffeeDecorator struct {
    coffee Coffee
}

func (c *CoffeeDecorator) Cost() float64 {
    return c.coffee.Cost()
}

func (c *CoffeeDecorator) Description() string {
    return c.coffee.Description()
}

// Concrete Decorator - Milk
type MilkDecorator struct {
    CoffeeDecorator
}

func NewMilkDecorator(coffee Coffee) *MilkDecorator {
    return &MilkDecorator{CoffeeDecorator{coffee: coffee}}
}

func (m *MilkDecorator) Cost() float64 {
    return m.coffee.Cost() + 0.50
}

func (m *MilkDecorator) Description() string {
    return m.coffee.Description() + ", Milk"
}

// Concrete Decorator - Sugar
type SugarDecorator struct {
    CoffeeDecorator
}

func NewSugarDecorator(coffee Coffee) *SugarDecorator {
    return &SugarDecorator{CoffeeDecorator{coffee: coffee}}
}

func (s *SugarDecorator) Cost() float64 {
    return s.coffee.Cost() + 0.25
}

func (s *SugarDecorator) Description() string {
    return s.coffee.Description() + ", Sugar"
}

// Concrete Decorator - Caramel Syrup
type CaramelDecorator struct {
    CoffeeDecorator
}

func NewCaramelDecorator(coffee Coffee) *CaramelDecorator {
    return &CaramelDecorator{CoffeeDecorator{coffee: coffee}}
}

func (c *CaramelDecorator) Cost() float64 {
    return c.coffee.Cost() + 1.00
}

func (c *CaramelDecorator) Description() string {
    return c.coffee.Description() + ", Caramel Syrup"
}

func main() {
    // Start with basic coffee
    coffee := &BasicCoffee{}
    fmt.Printf("%s: $%.2f\n", coffee.Description(), coffee.Cost())
    
    // Add milk
    coffeeWithMilk := NewMilkDecorator(coffee)
    fmt.Printf("%s: $%.2f\n", coffeeWithMilk.Description(), coffeeWithMilk.Cost())
    
    // Add sugar to coffee with milk
    coffeeWithMilkAndSugar := NewSugarDecorator(coffeeWithMilk)
    fmt.Printf("%s: $%.2f\n", coffeeWithMilkAndSugar.Description(), coffeeWithMilkAndSugar.Cost())
    
    // Add caramel to everything
    fancyCoffee := NewCaramelDecorator(coffeeWithMilkAndSugar)
    fmt.Printf("%s: $%.2f\n", fancyCoffee.Description(), fancyCoffee.Cost())
    
    // Let's create some different combinations
    fmt.Println("\nDifferent coffee orders:")
    
    // Just caramel coffee
    caramelCoffee := NewCaramelDecorator(&BasicCoffee{})
    fmt.Printf("%s: $%.2f\n", caramelCoffee.Description(), caramelCoffee.Cost())
    
    // Coffee with sugar only
    sweetCoffee := NewSugarDecorator(&BasicCoffee{})
    fmt.Printf("%s: $%.2f\n", sweetCoffee.Description(), sweetCoffee.Cost())
    
    // Premium coffee with everything
    premiumCoffee := NewCaramelDecorator(
        NewMilkDecorator(
            NewSugarDecorator(
                &BasicCoffee{},
            ),
        ),
    )
    fmt.Printf("%s: $%.2f\n", premiumCoffee.Description(), premiumCoffee.Cost())
}

▶ اجرای کد کپی ✖ بستن خروجی