Can you give an example of using the structural pattern in software system design?

Structural design patterns help organize relationships between classes and objects to simplify the system structure.

Example: the "Decorator" pattern.

It allows dynamically adding new responsibilities to objects by wrapping them in other decorator objects without changing the original class.

Example in Java:

// Component interface
interface Coffee {
    double cost();
    String ingredients();
}

// Concrete component
class SimpleCoffee implements Coffee {
    public double cost() { return 1.0; }
    public String ingredients() { return "Coffee"; }
}

// Decorator
class MilkDecorator implements Coffee {
    private Coffee coffee;
    public MilkDecorator(Coffee coffee) { this.coffee = coffee; }
    public double cost() { return coffee.cost() + 0.5; }
    public String ingredients() { return coffee.ingredients() + ", Milk"; }
}

// Usage
Coffee coffee = new MilkDecorator(new SimpleCoffee());
System.out.println(coffee.cost()); // 1.5
System.out.println(coffee.ingredients()); // Coffee, Milk

This approach allows flexible extension of functionality without modifying existing code.