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Modernising the Legacy Marek Matulka UK

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Marek Matulka Software Engineer SensioLabs UK @super_marek

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Legacy

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What is legacy code? - old code - poor quality code - no environments - no error logging (or excessive logging) - no tests

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It’s too hard - understand the logic - add new features - debug - fix bugs - adopt new technologies

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How do we get out of legacy?

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Example

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Start with the goal

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Why? Business goal

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Why? Who? Who? Actors

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Why? Who? Who? How? How? How? Impacts

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Why? Who? Who? How? How? How? What? What? What? What? What? What? Deliverables

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Why? Who? Who? How? How? How? What? What? What? What? What? What? Prioritise

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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?

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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

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Implement scenarios

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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

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(everything?) What to test?

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Unit tests Acceptance tests Integration tests End-to-end

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Unit tests Acceptance tests Integration tests End-to-end Manual Automated

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Unit tests Acceptance tests Integration tests End-to-end Slowest Fastest

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Why test?

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Why test? - code level documentation - features described through examples - clean code - you’re not afraid to change your code - peace of mind

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Why test? delivered features project’s life

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Why use Symfony components?

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Symfony Components The standard foundation on which the best PHP applications are built. - fully tested - decoupled - reusable - de-facto standard

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Symfony Components Build a micro framework. Use components you need in your application.

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standardised way to install components Composer

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composer.json { "require": { "php": ">=5.6.0" }, "require-dev": { "phpspec/phpspec": "~2.0" }, "config": { "bin-dir": "bin" }, "autoload": {"psr-0": {"": "src"}} }

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$ sudo dnf install composer

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$ curl -sS https://getcomposer.org/installer | php

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$ composer install

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$ composer update

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$ composer update package/name

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$ composer require package/name

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symfony/dependency-injection Dependency Injection

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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

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Dependency Injection PostageCalculator PostageRepository

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Dependency Inversion PostageCalculator PostageRepository

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Dependency Inversion PostageCalculator PostageRepository PostageSqliteRepository

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Dependency Inversion PostageCalculator PostageRepository PostageSqliteRepository PostageDoctrineRepository

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DI as a boundary Legacy code Quality de- coupled code DI

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Install dependency injection $ composer require symfony/dependency-injection $ composer require symfony/config

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Create container.php load('services.yml'); $container->compile();

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Create container.php load('services.yml'); $container->compile();

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Create container.php load('services.yml'); $container->compile();

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Create container.php load('services.yml'); $container->compile();

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Create container.php load('services.yml'); $container->compile();

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Create container.php load('services.yml'); $container->compile();

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# 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

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# 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

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# 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

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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("

Estimated postage for %d item(s): £%1.02f.

", $postage['quantity'], $postage['price'] ); } // ...

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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("

Estimated postage for %d item(s): £%1.02f.

", $postage['quantity'], $postage['price'] ); } // ...

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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("

Estimated postage for %d item(s): £%1.02f.

", $postage['quantity'], $postage['price'] ); } // ...

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Application Kernel

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container.php load('services.yml'); $container->compile();

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container.php load('services.yml'); $container->compile();

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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; } }

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container.php boot(); $container = $kernel->getContainer();

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Singleton Kernel

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boot(); } return static::$instance; } protected function __construct() {} private function __clone() {} private function __wakeup() {} }

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boot(); } return static::$instance; } protected function __construct() {} private function __clone() {} private function __wakeup() {} }

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$di = Kernel::getInstance()->getContainer(); $service = $di->get('acme.service.name');

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Dependency Injection with Drupal 7?

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container.php boot(); variable_set('di_container', $kernel->getContainer());

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container.php boot(); variable_set('di_container', $kernel->getContainer());

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public/sites/default/settings.php

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depot_locator.module get('acme.depot_locator')->locateDepot($postcode); $depot = $depotEntity->toArray(); set_depot_cookies($depot); return ['depot' => $depot]; }

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depot_locator.module get('acme.depot_locator')->locateDepot($postcode); $depot = $depotEntity->toArray(); set_depot_cookies($depot); return ['depot' => $depot]; }

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symfony/console Add console commands

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Install console component $ composer require symfony/console

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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()); } }

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app/console #!/usr/bin/php addCommands([ $container->get('acme.command.depot_locate'), ]); $application->run();

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$ app/console depot:locate wc1a1dg

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twig/twig Twig

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What is twig?

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Install twig $ composer require twig/twig

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How to use twig? render('index.html', ['variable' => 'value']);

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# 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

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# 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

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# 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

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# 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

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Use twig $basketViewData = $container->get('acme.basket.view') ->toView($_SESSION['basket']); $basketView = $container->get('twig.renderer') ->render( 'basket.twig.html', $basketViewData ); echo $basketView;

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symfony/http-foundation Decouple from global state

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Http application’s flow Controller Request Response

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Install HttpFoundation component $ composer require symfony/http-foundation

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De-coupling from global state # /public/basket.php get('acme.basket_view.controller') ->viewAction($request); $response->send();

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De-coupling from global state # /public/basket.php get('acme.basket_view.controller') ->viewAction($request); $response->send();

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De-coupling from global state # /public/basket.php get('acme.basket_view.controller') ->viewAction($request); $response->send();

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De-coupling from global state # /public/basket.php get('acme.basket_view.controller') ->viewAction($request); $response->send();

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Going forward

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Try it yourself! https://github.com/mareg/legacy-summercamp-2015 - four exercises: - add dependency injection - add twig - decouple from global state - controller as service

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Questions? Slides: speakerdeck.com/super_marek Feedback: joind.in/talk/view/15567 Connect on twitter: @super_marek