Structural Patterns

Overview

Structural patterns define how classes and objects are composed to form larger structures while keeping systems flexible.

Common Structural Patterns

• Adapter
• Facade
• Decorator
• Proxy
• Composite

flowchart LR
    A[Client] --> B[Facade]
    B --> C[Subsystem A]
    B --> D[Subsystem B]

Practical Example - Facade

public class CheckoutFacade
{
    public void CompleteOrder(Order order)
    {
        inventory.Reserve(order.Items);
        payment.Capture(order.Payment);
        shipping.Schedule(order.Address);
    }
}

Facade reduces integration complexity for callers.

Production Guidance

• Use adapter for legacy and third-party API integration
• Use decorator for optional behavior such as caching or tracing
• Use facade to simplify complex workflows

Common Pitfalls

• Hiding critical errors behind oversimplified facades
• Creating deep decorator chains that are hard to trace
• Using proxy without explicit latency and retry strategy

Key Takeaways

• Structural patterns improve composability and maintainability.
• Facade and adapter are practical in integration-heavy systems.
• Clear boundaries and observability keep these patterns manageable.