introduction to di(c)

Introduction to DI(C)

meet.php #! "#.$!.%$"%http://meetphp.pl/

$speaker = new Speaker;

$speaker->name = "Radosław Benkel";$speaker->twitter = "@singlespl";$speaker->blog = "http://blog.rbenkel.me";

$speaker->givePresentation();

About me

DependencyInjectionContainer

Dependency

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

$client = new TwitterApiClient;

Dependency

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

$client = new TwitterApiClient;

This�� is�� your�� dependency.

“What’s�� wrong�� with�� that”?

Dependency

Try testing it...

Dependency

...or change client implementation

Dependency

So let’s use Injection

Dependency

Injection

class TwitterAPIClient{ protected $httpClient; public function __construct($httpClient) { $this->httpClient = $httpClient; } /* ... */}

$client = new TwitterApiClient(new SomeCurlWrapper);

And�� here�� you�� inject�� dependency

Injection

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

public function __construct($httpClient){ $this->httpClient = $httpClient;}

it’s just like...

Injection

Try�� replacing�� battery,�� and�� you�� will�� now�� what�� I’m�� talking�� about.��

Injection types:

Injection

Injection types:

Injection

• constructor injection

Injection types:

Injection

• constructor injection• setter injection

Injection types:

Injection

• constructor injection• setter injection• interface injection

Constructor injection

Injection

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

Setter injection

Injection

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

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);

So far so good...

Injection

...until you don’t have to do something like

Injection

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'));

Injection

“How�� to�� solve�� that”?

Just use...

Injection

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'));

Container

require_once "container_dev.php";

/* mapper is UserMapperDB, with different PDO configuration. */$mapper->save(new User('John', 'Doe'));

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�� the�� difference

Container

Find�� the�� differenceConfigures�� services�� in�� different�� way,�� but�� for�� you,�� API�� for�� mapper�� is�� the�� same.

Container

Find�� the�� difference*�� Assuming,�� that�� all�� mappers�� share�� the�� same�� interface,�� which�� they�� rather�� should.

So, DIC it’s something like:

Container

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. )

So. Lets write simple one.

Container

Containerclass 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; } }}

Containerclass 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; } }}

*�� Inspired�� by�� Pimple

Lets use that.

Injection

Replacing this:

Injection

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'));

with this:

Injection

/* mapper is UserMapperEncrypted, which uses UserMapperCached (using Redis for cache), which uses UserMapperDB, which uses PDO. */$mapper->save(new User('John', 'Doe'));

Because everything is configured in container...

Injection

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')

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

Injection

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') );});

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') );});

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

Injection

/* mapper is UserMapperEncrypted, which uses UserMapperCached (using Apc for cache), which uses UserMapperDB, which uses PDO. */$mapper->save(new User('John', 'Doe'));

But probably, you should use another

Container

• AuraDIhttp://auraphp.github.com/Aura.Di/

• Pimplehttp://pimple.sensiolabs.org/

• Symfony % Dependency Injection Componenthttp://symfony.com/doc/current/components/dependency_injection/introduction.html

• ZF% Dependency Injectionhttp://framework.zend.com/wiki/display/ZFDEV%/Zend+DI+QuickStart

• Twitteehttp://twittee.org/

Container

PHP�� 5.4�� only

Container

Small,�� basic

Container

Lot’s�� of�� features

Container

Fits�� into�� tweet!

Thank you!

introduction to di(c)

di pimple http

wiki display zfdev2 zend di quickstart twittee http

public function construct

container auradi http

injection injection types

doc current components dependency injection introduction

client

shared false

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