Modernising the Legacy (ZendCon)

No one likes to work with the legacy projects - it's not fun. There are no specs, there are no behat examples and you're afraid to touch it. The customer may not have time or budget to spend on rewriting it from the scratch, but is likely to keep asking for the new features.

Learn how to work with the legacy code, how to add new features without breaking it. Learn to use Symfony components to support building sustainable features.

Transcript

1. Modernising the Legacy Marek Matulka UK
2. Marek Matulka Software Engineer SensioLabs UK @super_marek
4. Legacy
5. What is legacy code? - old code - poor quality code - no environments - no error logging (or excessive logging) - no tests
6. It’s too hard - understand the logic - add new features - debug - fix bugs - adopt new technologies
7. How do we get out of legacy?
11. Example
15. Start with the goal
16. Why? Business goal
17. Why? Who? Who? Actors
18. Why? Who? Who? How? How? How? Impacts
19. Why? Who? Who? How? How? How? What? What? What? What? What? What? Deliverables
20. Why? Who? Who? How? How? How? What? What? What? What? What? What? Prioritise
21. Goal: Reduce drop-outs by 10% In order to see the total cost of order As a shopper I want to see postage cost Example Why? Who? How? What?
22. Write scenarios Feature: Shopper can see postage cost In order to see the total cost of order As a shopper I want to see a postage cost Scenario: Shopper can see a postage cost Given I have added a "Clean Code" book priced £34.50 to the basket And the postage cost for one book is £3.50 When I check the basket Then I should see the postage cost of £3.50 And the total of the basket should be £38.00
23. Implement scenarios
24. Given-When-Then Feature: Shopper can see postage cost In order to see the total cost of order As a shopper I want to see a postage cost Scenario: Shopper can see a postage cost Given I have added a "Clean Code" book priced £34.50 to the basket And the postage cost for one book is £3.50 When I check the basket Then I should see the postage cost of £3.50 And the total of the basket should be £38.00
25. (everything?) What to test?
26. Unit tests Acceptance tests Integration tests End-to-end
27. Unit tests Acceptance tests Integration tests End-to-end Manual Automated
28. Unit tests Acceptance tests Integration tests End-to-end Slowest Fastest
29. Why test?
30. Why test? - code level documentation - features described through examples - clean code - you’re not afraid to change your code - peace of mind
31. Why test? delivered features project’s life
32. Why use Symfony components?
33. Symfony Components The standard foundation on which the best PHP applications are built. - fully tested - decoupled - reusable - de-facto standard
34. Symfony Components Build a micro framework. Use components you need in your application.
35. standardised way to install components Composer
37. composer.json { "require": { "php": ">=5.6.0" }, "require-dev": { "phpspec/phpspec": "~2.0" }, "config": { "bin-dir": "bin" }, "autoload": {"psr-0": {"": "src"}} }
38. $ sudo dnf install composer
39. $ curl -sS https://getcomposer.org/installer | php
40. $ composer install
41. $ composer update
42. $ composer update package/name
43. $ composer require package/name
44. symfony/dependency-injection Dependency Injection
45. Dependency Injection In software engineering, dependency injection is a software design pattern that implements inversion of control for resolving dependencies. Dependency injection means giving an object its instance variables. Really. That's it. https://en.wikipedia.org/wiki/Dependency_injection
46. Dependency Injection PostageCalculator PostageRepository
47. Dependency Inversion PostageCalculator PostageRepository
48. Dependency Inversion PostageCalculator PostageRepository PostageSqliteRepository
49. Dependency Inversion PostageCalculator PostageRepository PostageSqliteRepository PostageDoctrineRepository
50. DI as a boundary Legacy code Quality de- coupled code DI
51. Install dependency injection $ composer require symfony/dependency-injection $ composer require symfony/config
52. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
53. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
54. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
55. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
56. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
57. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
58. # app/config/services.yml services: acme.postage.repository: class: Acme\Infrastructure\Sqlite\PostageSqliteRepository acme.postage.calculator: class: Acme\Basket\PostageCalculator arguments: - @acme.postage.repository Create services.yml
59. # app/config/services.yml services: acme.postage.repository: class: Acme\Infrastructure\Sqlite\PostageSqliteRepository acme.postage.calculator: class: Acme\Basket\PostageCalculator arguments: - @acme.postage.repository Create services.yml
60. # app/config/services.yml services: acme.postage.repository: class: Acme\Infrastructure\Sqlite\PostageSqliteRepository acme.postage.calculator: class: Acme\Basket\PostageCalculator arguments: - @acme.postage.repository Create services.yml
61. Use container require '../_inc/db.php'; require '../app/container.php'; // ... $postageCalculator = $container->get('acme.postage.calculator'); if ($postage = $postageCalculator->calculateForBasket($_SESSION['basket'])) { $postage = $postage->toView(); echo sprintf("<p>Estimated postage for %d item(s): £%1.02f.</p>", $postage['quantity'], $postage['price'] ); } // ...
62. Use container require '../_inc/db.php'; require '../app/container.php'; // ... $postageCalculator = $container->get('acme.postage.calculator'); if ($postage = $postageCalculator->calculateForBasket($_SESSION['basket'])) { $postage = $postage->toView(); echo sprintf("<p>Estimated postage for %d item(s): £%1.02f.</p>", $postage['quantity'], $postage['price'] ); } // ...
63. Use container require '../_inc/db.php'; require '../app/container.php'; // ... $postageCalculator = $container->get('acme.postage.calculator'); if ($postage = $postageCalculator->calculateForBasket($_SESSION['basket'])) { $postage = $postage->toView(); echo sprintf("<p>Estimated postage for %d item(s): £%1.02f.</p>", $postage['quantity'], $postage['price'] ); } // ...
65. Application Kernel
66. container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
67. container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
68. <?php # src\Acme\Application\Kernel.php namespace Acme\Application; class Kernel { /** @var ContainerBuilder */ private $container; public function boot() { $this->container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $this->container->compile(); } public function getContainer() { return $this->container; } }
69. container.php <?php // app/container.php require __DIR__ . '/../vendor/autoload.php'; $kernel = (new \Acme\Application\Kernel())->boot(); $container = $kernel->getContainer();
70. Singleton Kernel
71. <?php # src\Acme\Application\Kernel.php namespace Acme\Application; class Kernel { public static $instance; // ... public static getInstance() { if (null === static::$instance) { static::$instance = (new static())->boot(); } return static::$instance; } protected function __construct() {} private function __clone() {} private function __wakeup() {} }
72. <?php # src\Acme\Application\Kernel.php namespace Acme\Application; final class Kernel { public static $instance; // ... public static getInstance() { if (null === static::$instance) { static::$instance = (new static())->boot(); } return static::$instance; } protected function __construct() {} private function __clone() {} private function __wakeup() {} }
73. $di = Kernel::getInstance()->getContainer(); $service = $di->get('acme.service.name');
74. Dependency Injection with Drupal 7?
75. container.php <?php require_once DRUPAL_ROOT . '/../vendor/autoload.php'; $kernel = (new \Acme\Application\Kernel())->boot(); variable_set('di_container', $kernel->getContainer());
76. container.php <?php require_once DRUPAL_ROOT . '/../vendor/autoload.php'; $kernel = (new \Acme\Application\Kernel())->boot(); variable_set('di_container', $kernel->getContainer());
77. public/sites/default/settings.php <?php // ... include_once 'config/container.php'; include 'database.php'; // ...
78. depot_locator.module <?php function get_depot_json($postcode) { $depotEntity = variable_get('di_container') ->get('acme.depot_locator')->locateDepot($postcode); $depot = $depotEntity->toArray(); set_depot_cookies($depot); return ['depot' => $depot]; }
79. depot_locator.module <?php function get_depot_json($postcode) { $depotEntity = variable_get('di_container') ->get('acme.depot_locator')->locateDepot($postcode); $depot = $depotEntity->toArray(); set_depot_cookies($depot); return ['depot' => $depot]; }
80. symfony/console Add console commands
81. Install console component $ composer require symfony/console
82. class LocateDepotCommand extends Command { /** @var DepotLocator */ private $depotLocator; public function __construct(DepotLocator $depotLocator) { $this->depotLocator = $depotLocator; parent::__construct(); } protected function configure() { $this->setName('depot:locate') ->addArgument('postcode', InputArgument::REQUIRED); } protected function execute(InputInterface $input, OutputInterface $output) { $this->depotLocator->locateDepot($input->getArgument('postcode')); $output->writeln('Nearest depot is located at: ' . $depot->getAddress()); } }
83. app/console #!/usr/bin/php <?php require_once (__DIR__ . '/../vendor/autoload.php'); require_once (__DIR__ . '/app/container.php'); use Symfony\Component\Console\Application; $application = new Application(); $application->addCommands([ $container->get('acme.command.depot_locate'), ]); $application->run();
84. $ app/console depot:locate wc1a1dg
85. twig/twig Twig
86. What is twig?
89. Install twig $ composer require twig/twig
90. How to use twig? <?php $loader = new Twig_Loader_Filesystem('/path/to/templates'); $twig = new Twig_Environment($loader); echo $twig->render('index.html', ['variable' => 'value']);
91. # app/config/services.yml parameters: twig.paths: - app/Resources/views services: twig.template_loader: class: Twig_Loader_Filesystem arguments: - %twig.paths% twig.renderer: class: Twig_Environment arguments: - @twig.template_loader Enabling twig in DI container
92. # app/config/services.yml parameters: twig.paths: - app/Resources/views services: twig.template_loader: class: Twig_Loader_Filesystem arguments: - %twig.paths% twig.renderer: class: Twig_Environment arguments: - @twig.template_loader Enabling twig in DI container
93. # app/config/services.yml parameters: twig.paths: - app/Resources/views services: twig.template_loader: class: Twig_Loader_Filesystem arguments: - %twig.paths% twig.renderer: class: Twig_Environment arguments: - @twig.template_loader Enabling twig in DI container
94. # app/config/services.yml parameters: twig.paths: - app/Resources/views services: twig.template_loader: class: Twig_Loader_Filesystem arguments: - %twig.paths% twig.renderer: class: Twig_Environment arguments: - @twig.template_loader Enabling twig in DI container
95. Use twig $basketViewData = $container->get('acme.basket.view') ->toView($_SESSION['basket']); $basketView = $container->get('twig.renderer') ->render( 'basket.twig.html', $basketViewData ); echo $basketView;
96. symfony/http-foundation Decouple from global state
97. Http application’s flow Controller Request Response
98. Install HttpFoundation component $ composer require symfony/http-foundation
99. De-coupling from global state # /public/basket.php <?php require __DIR__ . '/../app/container.php'; use Symfony\Component\HttpFoundation\Request; $request = Request::createFromGlobals(); $response = $container->get('acme.basket_view.controller') ->viewAction($request); $response->send();
100. De-coupling from global state # /public/basket.php <?php require __DIR__ . '/../app/container.php'; use Symfony\Component\HttpFoundation\Request; $request = Request::createFromGlobals(); $response = $container->get('acme.basket_view.controller') ->viewAction($request); $response->send();
101. De-coupling from global state # /public/basket.php <?php require __DIR__ . '/../app/container.php'; use Symfony\Component\HttpFoundation\Request; $request = Request::createFromGlobals(); $response = $container->get('acme.basket_view.controller') ->viewAction($request); $response->send();
102. De-coupling from global state # /public/basket.php <?php require __DIR__ . '/../app/container.php'; use Symfony\Component\HttpFoundation\Request; $request = Request::createFromGlobals(); $response = $container->get('acme.basket_view.controller') ->viewAction($request); $response->send();
103. Going forward
104. Try it yourself! https://github.com/mareg/legacy-summercamp-2015 - four exercises: - add dependency injection - add twig - decouple from global state - controller as service
105. Questions? Slides: speakerdeck.com/super_marek Feedback: joind.in/talk/view/15567 Connect on twitter: @super_marek