Presentation at #phpblt

1. Dependency Injection
And Pimple
2015.11.23 PHP BLT
@DQNEO

2. What is Dependency
Injection?
http://fabien.potencier.org/what-is-
dependency-injection.html
Fabien explained it well

3. Primitive Code
class User
{
public function __construct()
{
$this->storage = new Storage();
}

4. Dependency Injection
class User
{
public function __construct($storage)
{
$this->storage = $storage;
}

5. class MyController
{
public function indexAction()
{
$user = new User(new Storage());
}
Caller does

6. class MyController
{
public function indexAction($id)
{
$user = new User(new Storage(),$id);
}
Caller does

7. class MyController
{
public function indexAction($id)
{
$user = new User(new Storage(new Account()),
$id);
}
Caller does

8. class MyController
{
public function indexAction($id)
{
$user = new User(new Storage(new Account()),
$id);
}
Caller does
Too
Com
plicated

9. class MyController
{
public function indexAction($id)
{
$user = new User(new Storage(new Account()),
$id);
}
Caller does
new
書
い
と
る
や
ん
け

10. Solution
• Depenjency Injection Container
• etc

11. Pimple
https://github.com/silexphp/Pimple

12. How to use Pimple
// in bootstrap phase of your codes
use PimpleContainer;
$container = new Container();
// define a service
$container['storage'] = function ($c) {
return new Storage();
};

13. How to use Pimple
// in business logic of your codes
public function indexAction()
{
$storage = $this->$container[ storage ];
…
}

14. Internal of Pimple
class Container implements ArrayAccess
{
protected $values = [];
public function __construct(array $values = [])
{
$this->values = $values;
}
public function offsetSet($key, $value)
{
$this->values[$key] = $value;
}
public function offsetGet($key)
{
$value = $this->values[$key];
return is_callable($value)? $value($this) : $value;
}
public function offsetExists($key)
{
return array_key_exists($key, $this->values);
}
public function offsetUnset($key)
{
unset($this->values[$key]);
}
}

15. Internal of Pimple
class Container implements ArrayAccess

16. Internal of Pimple
public function offsetGet($key)
{
$value = $this->values[$key];
return is_callable($value)? $value($this) : $value;
}

17. Pimple pros/cons
• Loosely Coupling
• can make your app more testable
Pros
Cons
• reduce the power of IDE (wait for PHP7)
• Indirect programming