Symfony World - Symfony components and design patterns

1. Symfony Components and Design Patterns

3. Design patterns?

6. Why should you care?

7. Communication

8. Communication Reduced amount of code in one chunk

9. Communication Reduced amount of code in one chunk Increased cohesion and reduced coupling

10. Communication Reduced amount of code in one chunk Increased cohesion and reduced coupling Extendibility

11. Communication Reduced amount of code in one chunk Increased cohesion and reduced coupling Extendibility SOLID

12. Increase code quality

13. Can we measure it?

14. Avg. Logic Lines of Code

15. Avg. Logic Lines of Code LLoC

16. Avg. Logic Lines of Code LLoC Amount of classes

17. Avg. Logic Lines of Code LLoC Amount of classes AoC

18. Avg. Logic Lines of Code LLoC Amount of classes AoC Avg. Cyclomatic Complexity

19. Avg. Logic Lines of Code LLoC Amount of classes AoC Avg. Cyclomatic Complexity ACC

20. Let’s see the code

21. Sample Project

22. final class CheckoutController { private array $repository = []; public function cartAction(string $operation, array $options): Cart { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } // Apply promotion if ($cart->getPrice() >= 1000) { $cart->applyPercentageDiscount(0.1); } // Apply taxation /** @var CartItem $item */ foreach ($cart->getItems() as $item) { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } }

23. final class CheckoutController { private array $repository = []; public function cartAction(string $operation, array $options): Cart { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } // Apply promotion if ($cart->getPrice() >= 1000) { $cart->applyPercentageDiscount(0.1); } // Apply taxation /** @var CartItem $item */ foreach ($cart->getItems() as $item) { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; }

24. { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct( $options[‘product'], $options[‘type'], $options[‘quantity'], $options[‘price'] ); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } // Apply promotion if ($cart->getPrice() >= 1000) { $cart->applyPercentageDiscount(0.1); } // Apply taxation /** @var CartItem $item */ foreach ($cart->getItems() as $item) { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } // Save into repository

26. private array $repository = []; public function cartAction(string $operation, array $options): Cart { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } // Apply promotion if ($cart->getPrice() >= 1000) { $cart->applyPercentageDiscount(0.1); } // Apply taxation /** @var CartItem $item */ foreach ($cart->getItems() as $item) { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } // Save into repository $this->repository[$options['cart_id']] = $cart;

29. Avg. Logic Lines of Code 40 Amount of classes 1 Avg. Cyclomatic Complexity 8

30. LLoC AoC ACC Sample project 40 1 8

31. Single responsibility principle Open close principle Liskov substitution principle Interface segregation principle Dependency inversion principle

33. Composition

34. Preparation

36. $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } // Apply promotion if ($cart->getPrice() >= 1000) { $cart->applyPercentageDiscount(0.1); } // Apply taxation /** @var CartItem $item */ foreach ($cart->getItems() as $item) { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } }

37. private array $repository = []; public function cartAction(string $operation, array $options): Cart { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } // Apply promotion $this->applyPromotion($cart); // Apply taxation $this->applyTaxation($cart); // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } }

38. private function applyTaxation(Cart $cart): void { /** @var CartItem $item */ foreach ($cart->getItems() as $item) { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } } private function applyPromotion(Cart $cart): void { if ($cart->getPrice() >= 1000) { $cart->applyPercentageDiscount(0.1); } }

39. private array $repository = []; public function cartAction(string $operation, array $options): Cart { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } // Apply promotion $this->applyPromotion($cart); // Apply taxation $this->applyTaxation($cart); // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } }

40. final class CheckoutController { private array $repository = []; public function cartAction(string $operation, array $options): Cart { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } $this->processOrder($cart); // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } }

41. private function processOrder(Cart $cart): void { // Apply promotion $this->applyPromotion($cart); // Apply taxation $this->applyTaxation($cart); }

42. final class CheckoutController { private array $repository = []; public function cartAction(string $operation, array $options): Cart { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } $this->processOrder($cart); // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } private function applyTaxation(Cart $cart): void { /** @var CartItem $item */ foreach ($cart->getItems() as $item) { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } } private function applyPromotion(Cart $cart): void { if ($cart->getPrice() >= 1000) { $cart->applyPercentageDiscount(0.1); } } /** * @param Cart $cart */ private function processOrder(Cart $cart): void { // Apply promotion $this->applyPromotion($cart); // Apply taxation $this->applyTaxation($cart); } }

45. Extraction

46. final class CheckoutController { private array $repository = []; public function cartAction(string $operation, array $options): Cart { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } $this->orderProcessor->processOrder($cart); // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } }

47. final class CompositeOrderProcessor implements OrderProcessor { public function processOrder(Cart $cart): void { // Apply promotion $this->applyPromotion($cart); // Apply taxation $this->applyTaxation($cart); } private function applyTaxation(Cart $cart): void { /** @var CartItem $item */ foreach ($cart->getItems() as $item) { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } } private function applyPromotion(Cart $cart): void { if ($cart->getPrice() >= 1000) { $cart->applyPercentageDiscount(0.1); } } }

48. LLoC AoC ACC Sample project 40 1 8 Extracted processor 61 2 4.5

52. final class OrderTaxationProcessor implements OrderProcessor { public function processOrder(Cart $cart): void { /** @var CartItem $item */ foreach ($cart->getItems() as $item) { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } } }

53. final class CompositeOrderProcessor implements OrderProcessor { public function processOrder(Cart $cart): void { // Apply promotion $this->applyPromotion($cart); // Apply taxation $this->applyTaxation($cart); } private function applyPromotion(Cart $cart): void { if ($cart->getPrice() >= 1000) { $cart->applyPercentageDiscount(0.1); } } }

54. final class OrderPromotionProcessor implements OrderProcessor { public function processOrder(Cart $cart): void { if ($cart->getPrice() >= 1000) { $cart->applyPercentageDiscount(0.1); } } }

55. final class CompositeOrderProcessor implements OrderProcessor { private OrderPromotionProcessor $orderPromotionProcessor; private OrderTaxationProcessor $orderTaxationProcessor; public function __construct( OrderPromotionProcessor $orderPromotionProcessor, OrderTaxationProcessor $orderTaxationProcessor ) { $this->orderPromotionProcessor = $orderPromotionProcessor; $this->orderTaxationProcessor = $orderTaxationProcessor; } public function processOrder(Cart $cart): void { // Apply promotion $this->orderPromotionProcessor->processOrder($cart); // Apply taxation $this->orderTaxationProcessor->processOrder($cart); } }

56. LLoC AoC ACC Sample project 40 1 8 Extracted processor 61 2 4.5 Separated processors 76 4 2.75

58. final class CompositeOrderProcessor implements OrderProcessor { private OrderPromotionProcessor $orderPromotionProcessor; private OrderTaxationProcessor $orderTaxationProcessor; public function __construct( OrderPromotionProcessor $orderPromotionProcessor, OrderTaxationProcessor $orderTaxationProcessor ) { $this->orderPromotionProcessor = $orderPromotionProcessor; $this->orderTaxationProcessor = $orderTaxationProcessor; } public function processOrder(Cart $cart): void { // Apply promotion $this->orderPromotionProcessor->processOrder($cart); // Apply taxation $this->orderTaxationProcessor->processOrder($cart); } }

59. final class CompositeOrderProcessor implements OrderProcessor { private iterable $orderProcessors; public function __construct( OrderPromotionProcessor $orderPromotionProcessor, OrderTaxationProcessor $orderTaxationProcessor ) { $this->orderProcessors = [ $orderPromotionProcessor, $orderTaxationProcessor ]; } public function processOrder(Cart $cart): void { foreach ($this->orderProcessors as $orderProcessor) { $orderProcessor->processOrder($cart); } } }

63. final class CompositeOrderProcessor implements OrderProcessor { private iterable $orderProcessors; public function __construct(iterable $orderProcessors) { $this->orderProcessors = $orderProcessors; } public function processOrder(Cart $cart): void { foreach ($this->orderProcessors as $orderProcessor) { $orderProcessor->processOrder($cart); } } }

64. final class CompositeOrderProcessor implements OrderProcessor { private iterable $orderProcessors; public function __construct(iterable $orderProcessors) { $this->orderProcessors = $orderProcessors; } public function processOrder(Cart $cart): void { foreach ($this->orderProcessors as $orderProcessor) { $orderProcessor->processOrder($cart); } } }

65. SymfonyDesignPatternsProcessorOrderProcessor: class: 'SymfonyDesignPatternsProcessorCompositeOrderProcessor' arguments: - [ '@SymfonyDesignPatternsProcessorOrderPromotionProcessor', '@SymfonyDesignPatternsProcessorOrderTaxationProcessor' ]

66. Can Symfony help us with it?

67. SymfonyDesignPatternsProcessorOrderProcessor: class: 'SymfonyDesignPatternsProcessorCompositeOrderProcessor' arguments: - !tagged_iterator app.order_processor

68. SymfonyDesignPatternsProcessorOrderProcessor: class: 'SymfonyDesignPatternsProcessorCompositeOrderProcessor' arguments: - !tagged_iterator app.order_processor

69. SymfonyDesignPatternsProcessorOrderPromotionProcessor: tags: - app.order_processor SymfonyDesignPatternsProcessorOrderTaxationProcessor: tags: - app.order_processor

70. LLoC AoC ACC Sample project 40 1 8 Extracted processor 61 2 4.5 Separated processors 76 4 2.75 Composite iteration 73 4 3

72. LLoC AoC ACC Sample project 40 1 8 Composite iteration 73 4 3

73. Strategy

76. final class OrderTaxationProcessor implements OrderProcessor { private TaxationStrategyDelegator $taxationStrategy; public function __construct(TaxationStrategyDelegator $taxationStrategy) { $this->taxationStrategy = $taxationStrategy; } public function processOrder(Cart $cart): void { /** @var CartItem $item */ foreach ($cart->getItems() as $item) { $this->taxationStrategy->processTaxation($item); } } }

77. final class OrderTaxationProcessor implements OrderProcessor { private TaxationStrategyDelegator $taxationStrategy; public function __construct(TaxationStrategyDelegator $taxationStrategy) { $this->taxationStrategy = $taxationStrategy; } public function processOrder(Cart $cart): void { /** @var CartItem $item */ foreach ($cart->getItems() as $item) { $this->taxationStrategy->processTaxation($item); } } }

78. final class TaxationStrategyDelegator implements TaxationStrategy { public function processTaxation(CartItem $item): void { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } }

79. final class TaxationStrategyDelegator implements TaxationStrategy { public function processTaxation(CartItem $item): void { if ('shirt' === $item->getType()) { $item->setTaxationPercentage(0.23); } if ('book' === $item->getType()) { $item->setTaxationPercentage(0.08); } } }

80. final class TaxationStrategyDelegator implements TaxationStrategy { private ShirtTaxationStrategy $shirtTaxationStrategy; private BookTaxationStrategy $bookTaxationStrategy; public function __construct( ShirtTaxationStrategy $shirtTaxationStrategy, BookTaxationStrategy $bookTaxationStrategy ) { $this->shirtTaxationStrategy = $shirtTaxationStrategy; $this->bookTaxationStrategy = $bookTaxationStrategy; } public function processTaxation(CartItem $item): void { if ('shirt' === $item->getType()) { $this->shirtTaxationStrategy->processTaxation($item); } if ('book' === $item->getType()) { $this->bookTaxationStrategy->processTaxation($item); } } }

85. final class TaxationStrategyDelegator implements TaxationStrategy { private array $indexedTaxationStrategies; public function __construct( ShirtTaxationStrategy $shirtTaxationStrategy, BookTaxationStrategy $bookTaxationStrategy ) { $this->indexedTaxationStrategies = [ 'shirt' => $shirtTaxationStrategy, 'book' => $bookTaxationStrategy, ]; } public function processTaxation(CartItem $item): void { $this->indexedTaxationStrategies[$item->getType()]->processTaxation($item); } }

90. final class TaxationStrategyDelegator implements TaxationStrategy { private ServiceLocator $taxationStrategies; public function __construct(ServiceLocator $taxationStrategies) { $this->taxationStrategies = $taxationStrategies; } public function processTaxation(CartItem $item): void { $this->taxationStrategies->get($item->getType())->processTaxation($item); } }

91. final class TaxationStrategyDelegator implements TaxationStrategy { private ServiceLocator $taxationStrategies; public function __construct(ServiceLocator $taxationStrategies) { $this->taxationStrategies = $taxationStrategies; } public function processTaxation(CartItem $item): void { $this->taxationStrategies->get($item->getType())->processTaxation($item); } }

92. SymfonyDesignPatternsTaxationStrategiesTaxationStrategy: class: 'SymfonyDesignPatternsTaxationStrategiesTaxationStrategyDelegator' arguments: - !tagged_locator { tag: 'app.taxation_strategies', index_by: 'type' }

93. SymfonyDesignPatternsTaxationStrategiesTaxationStrategy: class: 'SymfonyDesignPatternsTaxationStrategiesTaxationStrategyDelegator' arguments: - !tagged_locator { tag: 'app.taxation_strategies', index_by: 'type' }

94. SymfonyDesignPatternsTaxationStrategiesBookTaxationStrategy: tags: - { name: 'app.taxation_strategies', type: 'book' } SymfonyDesignPatternsTaxationStrategiesShirtTaxationStrategy: tags: - { name: 'app.taxation_strategies', type: 'shirt' }

95. LLoC AoC ACC Sample project 40 1 8 Composite iteration 73 4 3 Strategy iteration 102 7 1.86

97. Time for small refactoring

98. final class CheckoutController { private array $repository = []; private OrderProcessor $orderProcessor; public function __construct(OrderProcessor $orderProcessor) { $this->orderProcessor = $orderProcessor; } public function cartAction(string $operation, array $options): Cart { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } $this->orderProcessor->processOrder($cart); // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } }

99. final class CheckoutController { private array $repository = []; private OrderProcessor $orderProcessor; public function __construct(OrderProcessor $orderProcessor) { $this->orderProcessor = $orderProcessor; } public function cartAction(string $operation, array $options): Cart { // Fetch object from repository if (isset($this->repository[$options['cart_id']])) { /** @var Cart $cart */ $cart = $this->repository[$options['cart_id']]; } else { $cart = new Cart($options['cart_id']); } // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } $this->orderProcessor->processOrder($cart); // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } }

100. final class CheckoutController { private OrderProcessor $orderProcessor; private CartRepository $cartRepository; public function __construct(OrderProcessor $orderProcessor, CartRepository $cartRepository) { $this->orderProcessor = $orderProcessor; $this->cartRepository = $cartRepository; } public function cartAction(string $operation, array $options): Cart { // Fetch object from repository $cart = $this->cartRepository->getCart($options['cart_id']); // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } $this->orderProcessor->processOrder($cart); // Save into repository $this->cartRepository->save($cart); return $cart; } }

101. final class CheckoutController { private OrderProcessor $orderProcessor; private CartRepository $cartRepository; public function __construct(OrderProcessor $orderProcessor, CartRepository $cartRepository) { $this->orderProcessor = $orderProcessor; $this->cartRepository = $cartRepository; } public function cartAction(string $operation, array $options): Cart { // Fetch object from repository $cart = $this->cartRepository->getCart($options['cart_id']); // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } $this->orderProcessor->processOrder($cart); // Save into repository $this->cartRepository->save($cart); return $cart; } }

102. final class InMemoryCartRepository implements CartRepository { private array $repository = []; public function getCart(string $cart_id): Cart { if (isset($this->repository[$cart_id])) { /** @var Cart $cart */ $cart = $this->repository[$cart_id]; } else { $cart = new Cart($cart_id); } return $cart; } }

103. public function getCart(string $cart_id): Cart { if (!isset($this->repository[$cart_id])) { $this->repository[$cart_id] = new Cart($cart_id); } /** @var Cart $cart */ return $this->repository[$cart_id]; }

104. LLoC AoC ACC Sample project 40 1 8 Composite iteration 73 4 3 Strategy iteration 102 7 1.86 Repository extraction 125 8 1.75

105. Command

106. final class CheckoutController { private array $repository = []; private OrderProcessor $orderProcessor; public function __construct(OrderProcessor $orderProcessor) { $this->orderProcessor = $orderProcessor; } public function cartAction(string $operation, array $options): Cart { // Fetch object from repository $cart = $this->cartRepository->getCart($options[‘cart_id']); // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } $this->orderProcessor->processOrder($cart); // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } }

107. final class CheckoutController { private array $repository = []; private OrderProcessor $orderProcessor; public function __construct(OrderProcessor $orderProcessor) { $this->orderProcessor = $orderProcessor; } public function cartAction(string $operation, array $options): Cart { // Fetch object from repository $cart = $this->cartRepository->getCart($options[‘cart_id']); // Perform operation if ('add_to_cart' === $operation) { $cart->addProduct($options['product'], $options['type'], $options['quantity'], $options['price']); } elseif ('remove_from_cart' === $operation) { $cart->removeProduct($options['product']); } else { throw new InvalidArgumentException('operation not supported'); } $this->orderProcessor->processOrder($cart); // Save into repository $this->repository[$options['cart_id']] = $cart; return $cart; } }

108. public function cartAction(string $operation, array $options): Cart { // Fetch object from repository $cart = $this->cartRepository->getCart($options['cart_id']); // Perform operation if ('add_to_cart' === $operation) { $this->messageBus->dispatch(new AddToCart( $options['cart_id'], $options['product'], $options['type'], $options['quantity'], $options['price'] )); } elseif ('remove_from_cart' === $operation) { $this->messageBus->dispatch(new RemoveFromCart( $options['cart_id'], $options['product'], )); } else { throw new InvalidArgumentException('operation not supported'); } $this->orderProcessor->processOrder($cart); // Save into repository $this->cartRepository->save($cart); return $cart; }

110. final class AddToCart { private string $cartId; private string $product; private string $type; private int $quantity; private int $price; public function __construct(...) { $this->cartId = $cartId; $this->product = $product; $this->type = $type; $this->quantity = $quantity; $this->price = $price; } }

111. final class AddToCartHandler implements MessageHandlerInterface { private CartRepository $cartRepository; public function __construct(CartRepository $cartRepository) { $this->cartRepository = $cartRepository; } public function __invoke(AddToCart $addToCart) { $cart = $this->cartRepository->getCart($addToCart->getCartId()); $cart->addProduct( $addToCart->getProduct(), $addToCart->getType(), $addToCart->getQuantity(), $addToCart->getPrice() ); $this->cartRepository->save($cart); } }

114. public function cartAction(CartIdAwareCommand $operation): Cart { // Fetch object from repository $cart = $this->cartRepository->getCart($operation->getCartId()); // Perform operation $this->messageBus->dispatch($operation); $this->orderProcessor->processOrder($cart); // Save into repository $this->cartRepository->save($cart); return $cart; }

115. public function cartAction(CartIdAwareCommand $operation): Cart { // Fetch object from repository $cart = $this->cartRepository->getCart($operation->getCartId()); // Perform operation $this->messageBus->dispatch($operation); $this->orderProcessor->processOrder($cart); // Save into repository $this->cartRepository->save($cart); return $cart; }

116. LLoC AoC ACC Sample project 40 1 8 Composite iteration 73 4 3 Strategy iteration 102 7 1.86 Repository extraction 125 8 1.75 Command iteration 209 12 1.33

117. Decorator

120. final class AddToCartHandler implements MessageHandlerInterface { private CartRepository $cartRepository; public function __construct(CartRepository $cartRepository) { $this->cartRepository = $cartRepository; } public function __invoke(AddToCart $addToCart): Cart { $cart = $this->cartRepository->getCart($addToCart->getCartId()); $cart->addProduct( $addToCart->getProduct(), $addToCart->getType(), $addToCart->getQuantity(), $addToCart->getPrice() ); return $cart; } }

121. final class AddToCartHandler implements MessageHandlerInterface { private CartRepository $cartRepository; public function __construct(CartRepository $cartRepository) { $this->cartRepository = $cartRepository; } public function __invoke(AddToCart $addToCart): Cart { $cart = $this->cartRepository->getCart($addToCart->getCartId()); $cart->addProduct( $addToCart->getProduct(), $addToCart->getType(), $addToCart->getQuantity(), $addToCart->getPrice() ); return $cart; } }

122. final class TransactionDecorator { private MessageHandlerInterface $messageHandler; private CartRepository $cartRepository; public function __construct( MessageHandlerInterface $messageHandler, CartRepository $cartRepository ) { $this->messageHandler = $messageHandler; $this->cartRepository = $cartRepository; } public function __invoke(CartIdAwareCommand $cartIdAwareCommand) { // start transaction $cart = ($this->messageHandler)($cartIdAwareCommand); $this->cartRepository->save($cart); } }

124. SymfonyDesignPatternsDecoratorTransactionDecorator: decorates: SymfonyDesignPatternsCommandHandlerAddToCartHandler arguments: - '@.inner'

125. LLoC AoC ACC Sample project 40 1 8 Composite iteration 73 4 3 Strategy iteration 102 7 1.86 Repository extraction 125 8 1.75 Command iteration 209 12 1.33 Decorator iteration 216 13 1.31

126. Take offs?

127. Trade offs!

132. Increased complexity

133. Increased complexity Increased testability

134. Increased complexity Increased testability Possibility for maintenance cost reduction

135. Symfony may help you a lot

136. @Sylius Thank you! @lukaszchrusciel

Symfony World - Symfony components and design patterns

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