Introduction to DI(C)

Quick introduction to Dependency Injection (Container).

Transcript

1. Introduction to DI(C)
   meet.php # . .
   http://meetphp.pl/
   

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2. $speaker = new Speaker;
   $speaker->name = "Radosław Benkel";
   $speaker->twitter = "@singlespl";
   $speaker->blog = "http://blog.rbenkel.me";
   $speaker->givePresentation();
   About me
   

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3. What?
   

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4. Dependency
   Injection
   Container
   What?
   

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5. Dependency
   What?
   

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6. Dependency
   class TwitterAPIClient
   {
   protected $httpClient;
   public function __construct()
   {
   $this->httpClient = new SomeCurlWrapper();
   }
   /* ... */
   }
   $client = new TwitterApiClient;
   

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7. Dependency
   class TwitterAPIClient
   {
   protected $httpClient;
   public function __construct()
   {
   $this->httpClient = new SomeCurlWrapper();
   }
   /* ... */
   }
   $client = new TwitterApiClient;
   This

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8. “What’s

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9. Try testing it...
   Dependency
   

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10. ...or change client
    implementation
    Dependency
    

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11. Dependency
    

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12. So let’s use Injection
    Dependency
    

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13. Injection
    What?
    

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14. Injection
    class TwitterAPIClient
    {
    protected $httpClient;
    public function __construct($httpClient)
    {
    $this->httpClient = $httpClient;
    }
    /* ... */
    }
    $client = new TwitterApiClient(new SomeCurlWrapper);
    And

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15. So...
    Injection
    

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16. Injection
    public function __construct()
    {
    $this->httpClient = new SomeCurlWrapper();
    }
    public function __construct($httpClient)
    {
    $this->httpClient = $httpClient;
    }
    VS
    

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17. it’s just like...
    Injection
    

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18. Injection
    VS
    

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19. Injection
    VS
    Try

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20. Injection types:
    Injection
    

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21. Injection types:
    Injection
    • constructor injection
    

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22. Injection types:
    Injection
    • constructor injection
    • setter injection
    

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23. Injection types:
    Injection
    • constructor injection
    • setter injection
    • interface injection
    

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24. Constructor injection
    Injection
    class TwitterAPIClient
    {
    protected $httpClient;
    public function __construct($httpClient)
    {
    $this->httpClient = $httpClient;
    }
    /* ... */
    }
    $client = new TwitterApiClient(new SomeCurlWrapper);
    

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25. Setter injection
    Injection
    class TwitterAPIClient
    {
    protected $httpClient;
    public function __construct() {}
    public function setHttpClient($httpClient) {
    $this->httpClient = $httpClient;
    }
    /* ... */
    }
    $client = new TwitterApiClient;
    $client->setHttpClient(new SomeCurlWrapper);
    

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26. Interface injection
    Injection
    interface HttpClientInterface {
    public function setHttpClient($httpClient);
    }
    class TwitterAPIClient implements HttpClientInterface {
    protected $httpClient;
    public function __construct() {}
    public function setHttpClient($httpClient) {
    $this->httpClient = $httpClient;
    }
    /* ... */
    }
    $client = new TwitterApiClient;
    $client->setHttpClient(new SomeCurlWrapper);
    

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27. So far so good...
    Injection
    

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28. ...until you don’t have
    to do something like
    that:
    Injection
    

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29. Injection
    $mapper = new UserMapperEncrypted(
    new UserMapperCached(
    new UserMapperDB(
    new PDO(
    'mysql:host=127.0.0.1',
    'user',
    'password'
    )
    ),
    new RedisCacheAdapter(
    '127.0.0.1:6379'
    )
    ),
    'YourSuperSecretPass'
    );
    $mapper->save(new User('John', 'Doe'));
    

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30. Injection
    

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31. Injection
    “How

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32. Just use...
    Injection
    

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33. Container
    What?
    

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34. Container
    require_once "container_prod.php";
    $mapper = $container->get('mapper.user');
    /* mapper is UserMapperEncrypted, which uses UserMapperCached,
    which uses UserMapperDB, which uses PDO. */
    $mapper->save(new User('John', 'Doe'));
    

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35. Container
    require_once "container_dev.php";
    $mapper = $container->get('mapper.user');
    /* mapper is UserMapperDB, with different PDO configuration.
    */
    $mapper->save(new User('John', 'Doe'));
    

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36. Container
    require_once "container_prod.php";
    $mapper = $container->get('mapper.user');
    $mapper->save(new User('John', 'Doe'));
    require_once "container_dev.php";
    $mapper = $container->get('mapper.user');
    $mapper->save(new User('John', 'Doe'));
    Find

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37. Container
    require_once "container_prod.php";
    $mapper = $container->get('mapper.user');
    $mapper->save(new User('John', 'Doe'));
    require_once "container_dev.php";
    $mapper = $container->get('mapper.user');
    $mapper->save(new User('John', 'Doe'));
    

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38. Container
    require_once "container_prod.php";
    $mapper = $container->get('mapper.user');
    $mapper->save(new User('John', 'Doe'));
    require_once "container_dev.php";
    $mapper = $container->get('mapper.user');
    $mapper->save(new User('John', 'Doe'));
    Find

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39. Container
    require_once "container_prod.php";
    $mapper = $container->get('mapper.user');
    $mapper->save(new User('John', 'Doe'));
    require_once "container_dev.php";
    $mapper = $container->get('mapper.user');
    $mapper->save(new User('John', 'Doe'));
    Find

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40. So, DIC it’s something
    like:
    Container
    

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41. Container
    

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42. What it does:
    Container
    • injects object dependencies
    • creates objects on demand
    • objects could be shared
    • (and sometimes other stuff, like tagging, XML/
    JSON/YAML config etc. )
    

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43. So. Lets write simple
    one.
    Container
    

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44. Container
    class Container
    {
    protected $items = array();
    public function get($key) {
    $item = $this->items[$key];
    return is_callable($item) ? $item($this) : $item;
    }
    public function set($key, $value, $shared = false) {
    if ($shared === true && is_callable($value)) {
    $this->items[$key] = function($c) use ($value) {
    static $obj;
    if (!$obj) {
    $obj = $value($c);
    }
    return $obj;
    };
    } else {
    $this->items[$key] = $value;
    }
    }
    }
    

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45. Container
    class Container
    {
    protected $items = array();
    public function get($key) {
    $item = $this->items[$key];
    return is_callable($item) ? $item($this) : $item;
    }
    public function set($key, $value, $shared = false) {
    if ($shared === true && is_callable($value)) {
    $this->items[$key] = function($c) use ($value) {
    static $obj;
    if (!$obj) {
    $obj = $value($c);
    }
    return $obj;
    };
    } else {
    $this->items[$key] = $value;
    }
    }
    }
    *

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46. Lets use that.
    Injection
    

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47. Replacing this:
    Injection
    

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48. Injection
    $mapper = new UserMapperEncrypted(
    new UserMapperCached(
    new UserMapperDB(
    new PDO(
    'mysql:host=127.0.0.1',
    'user',
    'password'
    )
    ),
    new RedisCacheAdapter(
    '127.0.0.1:6379'
    )
    ),
    'YourSuperSecretPass'
    );
    $mapper->save(new User('John', 'Doe'));
    

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49. with this:
    Injection
    

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50. Injection
    require_once "container_prod.php";
    $mapper = $container->get('mapper.user');
    /* mapper is UserMapperEncrypted, which uses UserMapperCached
    (using Redis for cache), which uses UserMapperDB, which uses
    PDO. */
    $mapper->save(new User('John', 'Doe'));
    

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51. Because everything is
    configured in
    container...
    Injection
    

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52. Injection
    //container_prod.php
    $c = new Container();
    $c->set('pdo.dsn', 'mysql:host=127.0.0.1');
    $c->set('pdo.user', 'user');
    $c->set('pdo.pass', 'password');
    $c->set('redis.host', '127.0.0.1:6379');
    $c->set('mcrypt.key', 'YourSuperSecretPass');
    $c->set('pdo', function(Container $c) {
    return new PDO(
    $c->get('pdo.dsn'),
    $c->get('pdo.user'),
    $c->get('pdo.pass'),
    );
    }, true);
    $c->set('cache.adapter', function(Container $c) {
    return new RedisCacheAdapter($c->get('redis.host'));
    });
    $c->set('mapper.user', function(Container $c) {
    return new UserMapperEncrypted(
    new UserMapperCached(
    new UserMapperDB($c->get('pdo')),
    $c->get('cache.adapter')
    ),
    $c->get('mcrypt.key')
    );
    });
    

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53. ...you can change e.g
    cache adapter...
    Injection
    

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54. Injection
    //container_prod.php
    $c = new Container();
    $c->set('pdo.dsn', 'mysql:host=127.0.0.1');
    $c->set('pdo.user', 'user');
    $c->set('pdo.pass', 'password');
    $c->set('mcrypt.key', 'YourSuperSecretPass');
    $c->set('pdo', function(Container $c) {
    return new PDO(
    $c->get('pdo.dsn'),
    $c->get('pdo.user'),
    $c->get('pdo.pass'),
    );
    }, true);
    $c->set('cache.adapter', function(Container $c) {
    return new ApcCacheAdapter();
    });
    $c->set('mapper.user', function(Container $c) {
    return new UserMapperEncrypted(
    new UserMapperCached(
    new UserMapperDB($c->get('pdo')),
    $c->get('cache.adapter')
    ),
    $c->get('mcrypt.key')
    );
    });
    

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55. Injection
    //container_prod.php
    $c = new Container();
    $c->set('pdo.dsn', 'mysql:host=127.0.0.1');
    $c->set('pdo.user', 'user');
    $c->set('pdo.pass', 'password');
    $c->set('mcrypt.key', 'YourSuperSecretPass');
    $c->set('pdo', function(Container $c) {
    return new PDO(
    $c->get('pdo.dsn'),
    $c->get('pdo.user'),
    $c->get('pdo.pass'),
    );
    }, true);
    $c->set('cache.adapter', function(Container $c) {
    return new ApcCacheAdapter();
    });
    $c->set('mapper.user', function(Container $c) {
    return new UserMapperEncrypted(
    new UserMapperCached(
    new UserMapperDB($c->get('pdo')),
    $c->get('cache.adapter')
    ),
    $c->get('mcrypt.key')
    );
    });
    

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56. ...and your your code
    hasn’t changed at all.
    Injection
    

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57. Injection
    require_once "container_prod.php";
    $mapper = $container->get('mapper.user');
    /* mapper is UserMapperEncrypted, which uses UserMapperCached
    (using Apc for cache), which uses UserMapperDB, which uses
    PDO. */
    $mapper->save(new User('John', 'Doe'));
    

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58. But probably, you
    should use another
    DIC:
    Container
    

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59. • AuraDI
    http://auraphp.github.com/Aura.Di/
    • Pimple
    http://pimple.sensiolabs.org/
    • Symfony Dependency Injection Component
    http://symfony.com/doc/current/components/dependency_injection/
    introduction.html
    • ZF Dependency Injection
    http://framework.zend.com/wiki/display/ZFDEV /Zend+DI+QuickStart
    • Twittee
    http://twittee.org/
    Container
    

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60. • AuraDI
    http://auraphp.github.com/Aura.Di/
    • Pimple
    http://pimple.sensiolabs.org/
    • Symfony Dependency Injection Component
    http://symfony.com/doc/current/components/dependency_injection/
    introduction.html
    • ZF Dependency Injection
    http://framework.zend.com/wiki/display/ZFDEV /Zend+DI+QuickStart
    • Twittee
    http://twittee.org/
    Container
    PHP

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61. • AuraDI
    http://auraphp.github.com/Aura.Di/
    • Pimple
    http://pimple.sensiolabs.org/
    • Symfony Dependency Injection Component
    http://symfony.com/doc/current/components/dependency_injection/
    introduction.html
    • ZF Dependency Injection
    http://framework.zend.com/wiki/display/ZFDEV /Zend+DI+QuickStart
    • Twittee
    http://twittee.org/
    Container
    Small,

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62. • AuraDI
    http://auraphp.github.com/Aura.Di/
    • Pimple
    http://pimple.sensiolabs.org/
    • Symfony Dependency Injection Component
    http://symfony.com/doc/current/components/dependency_injection/
    introduction.html
    • ZF Dependency Injection
    http://framework.zend.com/wiki/display/ZFDEV /Zend+DI+QuickStart
    • Twittee
    http://twittee.org/
    Container
    Lot’s

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63. • AuraDI
    http://auraphp.github.com/Aura.Di/
    • Pimple
    http://pimple.sensiolabs.org/
    • Symfony Dependency Injection Component
    http://symfony.com/doc/current/components/dependency_injection/
    introduction.html
    • ZF Dependency Injection
    http://framework.zend.com/wiki/display/ZFDEV /Zend+DI+QuickStart
    • Twittee
    http://twittee.org/
    Container
    Fits

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64. Thank you!
    

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