Better Code Design in PHP

Are you tired of spending hours reading code just to find the right place to make a small change?

Are you forced to split your application into several just so that devs don't step on each other's toes?

This talk unites theory with practice to show you how to structure your code so that it is easy to read, to test and to maintain. You will step out with concrete ideas of how to improve your code design.

Transcript

1. © Perforce Software, Inc. Better Code Design in PHP International PHP Conference Anna Filina | November 2024
2. © Perforce Software, Inc. Common pitfalls Project Agenda
3. © Perforce Software, Inc. Anna Filina • Coding since 1997 • PHP, Java, C#, etc. • Zend Professional Services • I fix your legacy • I write your tests • I teach you all my tricks
4. © Perforce Software, Inc. Common Pitfalls
5. © Perforce Software, Inc. Back-and-Forth Object Collaborator
6. © Perforce Software, Inc. One-Way Object Collaborator
7. © Perforce Software, Inc. Chatty Object Collaborator Step 1 Step 2 Step 3
8. © Perforce Software, Inc. Single Call Object Collaborator Task Step 1 Step 2 Step 3
9. © Perforce Software, Inc. What Drives My Design • Avoid complexity until I need it. • Can I understand the business use case?
10. © Perforce Software, Inc. Hard to Read $list = $this->repository->fetch(['column1' => $value . $seq . $suffix]); $filteredList = $this->filter->removeType($list, 2); $sortedList = $this->sorter->sort($filteredList, ['integers' => true]); $this->database->persist('table1', $sortedList);
11. © Perforce Software, Inc. Objects should speak business, not technical.
12. © Perforce Software, Inc. More Readable $lineItems = $this->orders->getLineItems($pendingOrderNumber); $taxTotals = $this->taxes->calculateForLineItems($lineItems);
13. © Perforce Software, Inc. Project
14. © Perforce Software, Inc. Short-Term Rental Marketplace • Search properties for rent by city, date and number of guests. • Reserve & pay.
15. © Perforce Software, Inc. Reservation ReservationService ->reserve() PaymentManager ReservationManager processPayment(data) Templating saveReservation(data) confirmReservation(data) html EmailManager payment savePayment(data) confirmReservation(html)
16. © Perforce Software, Inc. Reservation ReservationService ->reserve() PaymentManager ReservationManager Templating EmailManager processPayment(data) saveReservation(data) confirmReservation(data) html payment savePayment(data) confirmReservation(html)
17. © Perforce Software, Inc. Business Language MakeReservation PaymentProcessor ReservationRepository capture(charge) ReservationNotifier add(paidReservation) paymentConfirmation notifyBuyer(paidReservation)
18. © Perforce Software, Inc. Business Language MakeReservation PaymentProcessor ReservationRepository capture(charge) ReservationNotifier add(paidReservation) paymentConfirmation notifyBuyer(paidReservation)
19. © Perforce Software, Inc. Business Language MakeReservation PaymentProcessor ReservationRepository capture(charge) ReservationNotifier add(paidReservation) paymentConfirmation notifyBuyer(paidReservation)
20. © Perforce Software, Inc. Business Language MakeReservation PaymentProcessor ReservationRepository capture(charge) ReservationNotifier add(paidReservation) paymentConfirmation notifyBuyer(paidReservation)
21. © Perforce Software, Inc. Business Language MakeReservation PaymentProcessor ReservationRepository capture(charge) ReservationNotifier add(paidReservation) paymentConfirmation notifyBuyer(paidReservation)
22. © Perforce Software, Inc. Good design needs no diagrams.
23. © Perforce Software, Inc. Start in English Scenario: Guest can make a reservation Given I selected dates for a property When I submit valid payment details Then I should receive a reservation confirmation via e-mail
24. © Perforce Software, Inc. Search Scenario Scenario: Find property if the city, guests and dates match Given a property "Lviv for 4" in Lviv with 3 beds for 4 guests And the property is available on Jan 1 to Jan 31 When I search a property for 2 adults in Lviv on Jan 1 to Jan 7 Then I should see "Lviv for 4" in the results
25. © Perforce Software, Inc. Simple Code • No need for framework. • No need to design the database. • No need to have a UI. • Code the business rules.
26. © Perforce Software, Inc. From Gherkin to Code Scenario: Find property if the city, guests and dates match Given a property "Lviv for 4" in Lviv with 3 beds for 4 guests And the property is available on Jan 1 to Jan 31 When I search a property for 2 adults in Lviv on Jan 1 to Jan 7 Then I should see "Lviv for 4" in the results
27. © Perforce Software, Inc. From Gherkin to Design When I search a property for 2 adults in Lviv on Jan 1 to Jan 7 Then I should see "Lviv for 4" in the results Handle HTTP Request Return HTTP Response 2 adults in Lviv on Jan 1 to Jan 7 Results containing “Lviv for 4”
28. © Perforce Software, Inc. First Code $response = [ [ 'name' => 'Lviv for 4', 'price' => '$345 CAD', ] ];
29. © Perforce Software, Inc. Request/Response Handle HTTP Request Return HTTP Response 2 adults in Lviv on Jan 1 to Jan 7 Results containing “Lviv for 4”
30. © Perforce Software, Inc. Handle Function public function handle(array $request): array { return [ [ 'name' => 'Lviv for 4', 'price' => '$345 CAD', ] ]; }
31. © Perforce Software, Inc. Handler Class final readonly class PropertySearchHandler { public function handle(array $request): array { return [ [ 'name' => 'Lviv for 4’, 'price' => '$345 CAD’, ] ]; } } When I search a property [...]
32. © Perforce Software, Inc. Execute // public/index.php $url = parse_url($_SERVER['REQUEST_URI']); $response = match ($url['path']) { '/' => (new PropertySearchHandler())->handle($_GET), }; header('Content-Type: application/json'); echo json_encode($response);
33. © Perforce Software, Inc. PHP Server php -S localhost:8000 -t public/
34. © Perforce Software, Inc. Output
35. © Perforce Software, Inc. ” ” “A complex system that works is invariably found to have evolved from a simple system that worked.” — John Gall
36. © Perforce Software, Inc. Classes return [ new Property('Lviv 4', '$345 CAD'), ];
37. © Perforce Software, Inc. Too reusable becomes unusable.
38. © Perforce Software, Inc. Property final readonly class Property { public function __construct( public string $name, public string $price, ) { } }
39. © Perforce Software, Inc. Usage return match ($request['city']) { 'Lviv' => [ new Property('Lviv for 4', '$345 CAD'), ], 'Odesa' => [ new Property('Odesa 4', '$310 CAD'), new Property('Luxury Odesa 4', '$525 CAD'), ], };
40. © Perforce Software, Inc. Output
41. © Perforce Software, Inc. My Coding Order Input/output Business rules Infrastructure Use case
42. © Perforce Software, Inc. SearchCriteria $criteria = new SearchCriteria($request['city']); return match ($criteria->city) { // ... };
43. © Perforce Software, Inc. SearchCriteria final readonly class SearchCriteria { public function __construct( public string $city, // can be validated ) { } }
44. © Perforce Software, Inc. Problem with City return match ($criteria->city) { 'Lviv' => [ new Property('Lviv for 4', '$345 CAD'), ], 'Odesa' => [ new Property('Odesa 4', '$310 CAD'), new Property('Luxury Odesa 4', '$525 CAD'), ], };
45. © Perforce Software, Inc. Coordinates $coordinates = match ($criteria->city) { 'Lviv' => new Coordinates(49.8397, 24.0297), 'Odesa' => new Coordinates(46.4825, 30.7233), };
46. © Perforce Software, Inc. Coordinates $coordinates = match ($criteria->city) { 'Lviv' => new Coordinates(49.8397, 24.0297), 'Odesa' => new Coordinates(46.4825, 30.7233), }; return match ($coordinates->latitude) { 49.8397 => [ new Property('Lviv for 4', '$345 CAD'), ], 46.4825 => // ..., };
47. © Perforce Software, Inc. Output
48. © Perforce Software, Inc. Improvements $coordinates = match ($criteria->city) { 'Lviv' => new Coordinates(49.8397, 24.0297), 'Odesa' => new Coordinates(46.4825, 30.7233), }; return match ($coordinates->latitude) { 49.8397 => [ new Property('Lviv for 4', '$345 CAD'), ], 46.4825 => // ..., };
49. © Perforce Software, Inc. SQL SELECT name, price, ST_DISTANCE_SPHERE ( POINT(:search_longitude, :search_latitude), POINT(longitude, latitude) ) * .001 AS `distance_in_km` FROM `properties` HAVING `distance_in_km` <= :max_distance;
50. © Perforce Software, Inc. SQL SELECT name, price, ST_DISTANCE_SPHERE ( POINT(:search_longitude, :search_latitude), POINT(longitude, latitude) ) * .001 AS `distance_in_km` FROM `properties` HAVING `distance_in_km` <= :max_distance;
51. © Perforce Software, Inc. Usage return $this->propertyRepository->findWithinRadius( $coordinates, self::DEFAULT_RANGE );
52. © Perforce Software, Inc. Problem with City Names
53. © Perforce Software, Inc. Problem PropertySearchHandler Lviv, Lviv Oblast, Ukraine Convert to coordinates. CitySearchHandler Lviv - Lviv, Lviv Oblast, Ukraine - Lviv Boulevard, Oshawa, ON
54. © Perforce Software, Inc. Reorganize public function handle(array $request): array { $searchCriteria = SearchCriteria::fromRequest($request); // ... return $this->propertyRepository->find($searchCriteria); }
55. © Perforce Software, Inc. Problem PropertySearchHandler 49.8397, 24.0297 Longitude: -180 to +180 Latitude: -90 to +90 CitySearchHandler Lviv Lviv, Lviv Oblast, Ukraine 49.8397 24.0297
56. © Perforce Software, Inc. Reorganize final readonly class SearchCriteria { public function __construct( public string $city, ) { } }
57. © Perforce Software, Inc. Code is simply a model of the business rules and knowledge.
58. © Perforce Software, Inc. Thank You @afilina@phpc.social @afilina afilina@perforce.com