Dependency Injection with PHP

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Dependency Injection with PHP @BastianHofmann

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Dependency Injection Dependency Injection Containers Dependency Inversion Dependencies

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ResearchGate gives science back to the people who make it happen. We help researchers build reputation and accelerate scientiﬁc progress. On their terms. ‟

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Questions? Ask!

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http://speakerdeck.com/u/bastianhofmann

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Dependency Inversion

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http://www.doolwind.com/blog/solid-principles-for-game-developers/

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http://qafoo.com/presentations.html

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http://www.doolwind.com/blog/solid-principles-for-game-developers/

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High-level modules should not depend on low level modules but on abstractions. ”

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A B C

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A B C <> <>

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A B C <>

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A B Adapter <> C

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Dependency Injection

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Constructor

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Setter

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Method argument

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Constructing classes

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Beneﬁts

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Easier to change

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Easier testing

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Only test the class, not the dependencies

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Mocking

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http://www.doolwind.com/blog/solid-principles-for-game-developers/

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But...

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Make it easier with factories

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Dependency Injection Container

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rg\injektor inspired by google-guice

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https://github.com/researchgate/injektor

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http://getcomposer.org/ http://packagist.org/

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$ cat composer.json

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$ wget http://getcomposer.org/composer.phar $ php composer.phar install Installing dependencies - Installing monolog/monolog (1.1.0) Downloading: 100% ... monolog/monolog suggests installing mlehner/ gelf-php (Allow sending log messages to a GrayLog2 server) Writing lock file Generating autoload files

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Creating an instance of a class

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PHP 5.5

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Automatic creation of dependencies through Typehints

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@inject

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What classes can be injected?

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No constructor

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Constructor without arguments

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Constructor with arguments that have default values

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Injectable constructor

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By the way: Property Injection

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Singletons with public static getInstance method following the same rules

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STOP: Don‘t use Singeltons

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Singletons are evil!

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Let the DIC take care of instances

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@singleton

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Passing additional, ﬁxed values to instance

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Working with Interfaces

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But we can not create an instance of an Interface!

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@implementedBy

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Named @implementedBy

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Providers

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@providedBy

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Method invocation at DIC

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Same rules

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And if you don‘t like annotations... ... or want to integrate 3rd party code

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Great! So, how does it work?

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Development: Reﬂection

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Production: Generated Factory Classes

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https://github.com/bashofmann/dic_demo/

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DEMO

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https://github.com/symfony/DependencyInjection

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https://github.com/bashofmann/dic_demo/

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DEMO

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https://github.com/zendframework/zf2

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Automatic creation of dependencies through Typehints

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https://github.com/bashofmann/dic_demo/

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DEMO

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AOP

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http://ﬂow3.typo3.org/documentation/guide/partiii/ aspectorientedprogramming.html

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class Forum { /** * @FLOW3\Inject * @var ApplicationLoggerInterface */ protected $applicationLogger; /** * @param Post $post * @return void */ public function deletePost(Post $post) { $this-‐>applicationLogger-‐>log('Removing post'); $this-‐>posts-‐>remove($post); } }

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class Forum { /** * Delete a forum post * * @param Post $post * @return void */ public function deletePost(Post $post) { $this-‐>posts-‐>remove($post); } }

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/** * @FLOW3\Aspect */ class LoggingAspect { /** * @FLOW3\Inject * @var ApplicationLoggerInterface */ protected $applicationLogger; /** * @FLOW3\Before("method(Forum-‐>deletePost())") */ public function logDeletePost(\TYPO3\FLOW3\AOP \JoinPointInterface $joinPoint) { $post = $joinPoint-‐>getMethodArgument('post'); $this-‐>applicationLogger-‐>log('Removing'); } }

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h"p://twi"er.com/Bas2anHofmann h"p://proﬁles.google.com/bashofmann h"p://lanyrd.com/people/Bas2anHofmann h"p://speakerdeck.com/u/bas2anhofmann h"ps://github.com/bashofmann mail@bas2anhofmann.de Did you like this talk? https://joind.in/7346