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I am interested in writing my own IoC/ DIC for PHP based on the way Laravel works. This is purely for learning as it interests me and I want to understand the concept better.

I've been reading the Laravel documentation for Service Containers and Laravel IoC. I understand the concept and why dependency injection is good practice but what I am failing to grasp is how such functionality is coded.

Take this example from Laravel:

class UserController extends Controller
{
    /**
     * The user repository implementation.
     *
     * @var UserRepository
     */
    protected $users;

    /**
     * Create a new controller instance.
     *
     * @param  UserRepository  $users
     * @return void
     */
    public function __construct(UserRepository $users)
    {
        $this->users = $users;
    }
}

My question is how does UserRepository get injected code wise on the PHP side? How does the Laravel framework operate in the background on this? I read that Laravel may use the reflection class in PHP to achieve this, but I am unsure?

I also understand there are also a few different ways of doing dependency injection such as using setter methods or resolving classes using a static function? I am adware of and found useful the Pimple Project to aid in my understanding but I am more after how the Laravel way works with the automatic class injection, could someone give me a quick example I can go off and build from? Because with the way Laravel works and its DIC, there is no call for UserRepository via a function, it just gets injected? - That is what I am interested in, how I can code that myself.

I read also that a proper DIC would allow you to write configs for each class in different ways, such as XML or in PHP code, a way to setup the class instance before being injected, is this correct?

And is there any difference between IoC(Inversion of Control) and DIC(Dependency Injection Container)?

Also, what is the difference between Laravel Service Container and IoC in this case?

tty2018
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    This is pretty broad. This would be better for a teacher or mentor, or at the very least a discussion forum. Not really a great fit for a Q&A site like Stackoverflow. With that said, Laravel and most container implementations are open source, you could read through the code. Laravel does use reflection and then resolves the type hinted classes from the container. – Devon Bessemer Nov 20 '18 at 15:16
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    You should certainly take a look at the concept of [Pure DI](http://blog.ploeh.dk/2014/06/10/pure-di//). – Steven Nov 20 '18 at 18:22
  • @Devon I understand that there is a lot to my question but I think the main thing is, I am interested in how the injection works for `UserRepository` in the end :) There is a similar question [here](https://stackoverflow.com/questions/18562752/understanding-ioc-containers-and-dependency-injection) which is quite long but for me it doesn't touch on the auto DI like Laravel does. – tty2018 Nov 21 '18 at 06:30
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    If you look at reflection, I think you'll find it isn't that complicated. It uses reflection to get the class name, then resolves that class name from the container and provides it as a parameter to the method or constructor. – Devon Bessemer Nov 21 '18 at 13:56

0 Answers0