Tag: design-patterns

How to integrate legacy APIs, third-party libraries, and incompatible interfaces using object adapters, class adapters, and facade adapters in Java, TypeScript, and Python.

How to separate read and write models using Command Query Responsibility Segregation for optimized queries, event sourcing, and independent scaling of read and write paths.

How to structure code around business concepts using bounded contexts, aggregates, entities, value objects, and domain events to manage complexity in large applications.

How to use factory methods, abstract factories, and dependency injection containers to decouple object creation from usage and improve testability.

How to structure applications using ports and adapters to isolate business logic from frameworks, databases, and external services for testability and flexibility.

How to build event-driven, reactive systems using the observer pattern with pub/sub, event emitters, and reactive streams in JavaScript, Java, and Python.

How to guarantee exactly one instance of a class exists in an application using lazy initialization, thread-safe creation, and registry-based singletons.

How to encapsulate interchangeable algorithms and behaviors using the strategy pattern with dependency injection, function pointers, and lambda strategies in Java, TypeScript, and Python.

Create families of related objects without specifying concrete classes, enabling platform-specific implementations that share a common interface

Use the Adapter pattern to normalize responses from external REST APIs into a consistent internal model without leaking third-party formats into your domain

Add a local ambassador that handles retries, circuit breaking, and monitoring when calling remote services, keeping the client simple and the service logic pure

Separate an abstraction from its implementation so both can vary independently using the Bridge pattern for pluggable UI themes and rendering engines

Use the Builder pattern to construct complex configuration objects with optional parameters and sensible defaults without telescoping constructors

Pass requests along a chain of handlers where each handler decides whether to process the request or pass it to the next handler in the pipeline

Implement the Command pattern to encapsulate requests as objects, enabling undo/redo operations, request queuing, and operation logging

Use the Composite pattern to compose objects into tree structures, letting clients treat individual objects and compositions uniformly in UI component hierarchies

Use the Decorator pattern to compose cross-cutting concerns like logging, metrics, and retries into HTTP request pipelines without modifying core logic

Build a lightweight DI container that resolves class dependencies automatically, enabling testable, loosely-coupled applications without frameworks like Angular or InversifyJS

Use the Flyweight pattern to minimize memory usage by sharing as much data as possible between similar objects, essential for rendering large datasets

Build a language interpreter that evaluates expressions and rules by representing grammar as composable objects, useful for formulas, queries, and business rules

Provide a way to access elements of an aggregate object sequentially without exposing its underlying representation using the Iterator pattern

Reduce chaotic dependencies between UI components by introducing a mediator that centralizes communication, preventing explicit references between peers

Capture and externalize an object's internal state without violating encapsulation, enabling undo, serialization, and state rollback in applications

Apply the Model-View-Controller pattern to React and Vue applications to separate data, UI, and interaction logic for maintainable component architecture

Create new objects by copying existing ones, allowing pre-configured templates and avoiding subclass explosion when object creation is expensive

Implement a type-safe repository pattern in TypeScript that decouples data access logic from domain services using generics and interfaces

Apply the five SOLID principles to TypeScript code to improve maintainability, testability, and reduce coupling in object-oriented designs

Separate algorithms from the objects they operate on, allowing new operations to be added without modifying existing element classes

A user story template that connects user needs to implementation with clear acceptance criteria, definition of done, and INVEST principles.

A practical guide to useful code reviews: how to write reviewable code, give constructive feedback, and keep reviews fast and focused.

A guide to selecting and applying the right design pattern for common software engineering problems.

Learn the five SOLID principles with practical code examples: Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion.