Developing SOLID Code
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The document discusses the SOLID principles of object-oriented programming, highlighting their importance in improving code architecture and promoting clean code practices. It covers each principle: Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion, providing practical examples and benefits such as decoupled code and easier testing. Additionally, it emphasizes clean architecture benefits including enhanced scalability, reduced bugs, and improved team velocity.
![Practical Examples
class UserEntity implements HydratorInterface, ToArrayInterface
{
protected int $id;
protected string $username;
protected bool $isActive;
public function hydrate(array $data)
{
$this->setId($data['id']);
$this->setUsername($data['username']);
$this->setIsActive($data['is_active']);
}
public function toArray(): array
{
return [
'id' => $this->getId(),
'username' => $this->getUsername(),
'is_active' => $this->getIsActive(),
];
}](https://image.slidesharecdn.com/developingsolidcode-220218142059/85/Developing-SOLID-Code-35-320.jpg)
Developing SOLID Code
- 1. Developing SOLID Code Mark Niebergall https://www.slideshare.net/MarkNiebergall/developing-solid-code
- 2. Objective • Understand SOLID principles • Improve code architecture
- 3. Overview • SOLID Principles • Practical Examples • Clean Architecture Bene fi ts
- 4. SOLID Principles • 5 Principle of OOP • Promote clean code architecture • Basis of stable code
- 5. • S - Single-Responsibility • O - Open/Closed • L - Liskov Substitution • I - Interface Segregation • D - Dependency Inversion SOLID Principles
- 6. SOLID Principles • S - Single-Responsibility
- 7. SOLID Principles class Square { public float $length; public function calculateArea(): float { return $this->length * $this->length; } public function calculateCircleArea(float $radius): float { return pi() * pow($radius, 2); } }
- 8. SOLID Principles abstract class Shape { abstract public function calculateArea(): float; } class Circle extends Shape { public float $radius; public function calculateArea(): float { return pi() * pow($this->radius, 2); } }
- 9. SOLID Principles • S - Single-Responsibility - Do 1 thing - Do that thing well
- 10. SOLID Principles • S - Single-Responsibility - Decoupled code - Easier to test
- 11. SOLID Principles • S - Single-Responsibility - Entity - Service - Factory - Validator - Handler - Middleware - Action - Controller - Response
- 12. SOLID Principles • S - Single-Responsibility - Worker - Queue - Cmd - Adapter - Client
- 13. SOLID Principles • S - Single-Responsibility - Abstract - Interface - Trait - Enum
- 14. SOLID Principles • O - Open/Closed
- 15. SOLID Principles class Pet { public function walk(): void { $this->putOnLeash(); $this->walkOutside(); } public function feed($food): void { $this->pourFoodInDish($food); } }
- 16. SOLID Principles abstract class PetAbstract { public function __construct(protected string $name) { } public function getName(): string { return $this->name; } abstract public function feed(Food $food): void; } class Snake extends PetAbstract { public function feed(Food $food): void { // place food in habitat } }
- 17. SOLID Principles • O - Open/Closed - Open for extension - Closed for modi fi cation
- 18. SOLID Principles • O - Open/Closed - Extend class instead of altering
- 19. SOLID Principles • L - Liskov Substitution
- 20. SOLID Principles class Duck { public function fly(): bool { // ducks can fly! return true; } } class RubberDuck extends Duck { public function fly(): bool { // rubber ducks can't fly return false; } }
- 21. SOLID Principles • L - Liskov Substitution - Replaceable by subtypes - Do not alter parent class
- 22. SOLID Principles • L - Liskov Substitution - Covariance for return types
- 23. SOLID Principles • I - Interface Segregation
- 24. SOLID Principles interface EmployeeInterface { public function checkEmail(): bool; public function createPullRequest(): PullRequest; public function attendMeeting(Meeting $meeting): void; }
- 25. SOLID Principles • I - Interface Segregation - Many client-speci fi c interfaces are better than one general-purpose interface - Keep interfaces simple
- 26. SOLID Principles • I - Interface Segregation - Remember the S for Single-Responsibility
- 27. SOLID Principles • I - Interface Segregation - Most PHPFIG PSRs are interfaces ‣ HTTP Handlers, Client ‣ Cache ‣ Factories ‣ Logging
- 28. SOLID Principles • D - Dependency Inversion
- 29. SOLID Principles class UserService { protected HotmailEmailClient $hotmailEmailClient; public function setHotmailEmailClient(HotmailEmailClient $hotmailEmailClient): void { $this->hotmailEmailClient = $hotmailEmailClient; } public function emailUser(User $user): bool { $emailMessage = new EmailMessage(); $emailMessage->setEmailAddress($user->getEmailAddress()); return $this->hotmailEmailClient->sendEmail($emailMessage); } }
- 30. SOLID Principles class ContactService { protected EmailClientInterface $emailClient; public function setEmailClient(EmailClientInterface $emailClient): void { $this->emailClient = $emailClient; } public function sendEmail( Contact $contact, EmailMessageInterface $emailMessage ): bool { $emailMessage->setEmailAddress($contact->getEmailAddress()); return $this->emailClient->sendEmail($emailMessage); } }
- 31. SOLID Principles • D - Dependency Inversion - Use interfaces, abstracts rather than concrete classes
- 32. SOLID Principles • D - Dependency Inversion - Law of Demeter ‣ No reaching through to object’s objects
- 33. SOLID Principles • D - Dependency Inversion - Promotes code reuse - Promotes code compatibility
- 35. Practical Examples class UserEntity implements HydratorInterface, ToArrayInterface { protected int $id; protected string $username; protected bool $isActive; public function hydrate(array $data) { $this->setId($data['id']); $this->setUsername($data['username']); $this->setIsActive($data['is_active']); } public function toArray(): array { return [ 'id' => $this->getId(), 'username' => $this->getUsername(), 'is_active' => $this->getIsActive(), ]; }
- 36. Practical Examples class AuditRequestMiddleware implements MiddlewareInterface { public function __construct(protected AuditService $auditService) { } public function process( ServerRequestInterface $request, RequestHandlerInterface $handler ): ResponseInterface { $response = $handler->handle($request); $this->auditService->auditRequest($request, $response); return $response; } }
- 37. • Other ideas? Practical Examples
- 39. Clean Architecture Bene fi ts • Promotes other best practices - DDD: Domain Driven Design - DRY: Don’t Repeat Yourself - KISS: Keep It Simple, Stupid - YANGI: You Ain’t Gonna Need It - OOP: Object Oriented Programming
- 40. Clean Architecture Bene fi ts • Promotes code reuse - Write fewer tests! - Lower maintenance
- 41. Clean Architecture Bene fi ts • Introduce fewer bugs - Code stabilization - Less brittle code
- 42. Clean Architecture Bene fi ts • Decoupled Code - Easier architecture to unit test - Easier to read - Easier to use - Easier to upgrade packages - Easier to swap out third-party providers
- 43. Clean Architecture Bene fi ts • More features, less debugging - Improve team velocity - More time delivering value - Less time debugging unstructured code and data
- 44. Clean Architecture Bene fi ts • Improved Scalability - Add new tables, columns - Already setup to expand domains
- 45. Clean Architecture Bene fi ts • Con fi dence in authored code - Reduce unknowns - Testable code
- 46. Clean Architecture Bene fi ts • Other?
- 47. Review • S - Single-Responsibility • O - Open/Closed • L - Liskov Substitution • I - Interface Segregation • D - Dependency Inversion
- 48. SOLID Principles • Questions? • Discussion points?
- 49. Mark Niebergall @mbniebergall • PHP since 2005 • Masters degree in MIS • Senior Software Engineer • Vulnerability Management project (security scans) • Utah PHP Co-Organizer • CSSLP, SSCP Certi fi ed and SME • Endurance sports, outdoors
- 50. References • https://www.hashbangcode.com/article/solid-principles- php • https://levelup.gitconnected.com/solid-principles- simpli fi ed-php-examples-based-dc6b4f8861f6 • https://www.digitalocean.com/community/ conceptual_articles/s-o-l-i-d-the- fi rst- fi ve-principles-of- object-oriented-design