Laravel 5 what is the reason of binding namespaces in Service Provider?

Question

I read articles about Laravel service providers and containers. I understand that Service Provider is a way to organize service objects bindings to the IoC, useful when your application is fairly large.

But then I looked up in the ready service provider folder and saw this AppServiceProvider provider and the register method if it:

public function register()
{
    $this->app->bind(
        'Illuminate\Contracts\Auth\Registrar',
        'App\Services\Registrar'
    );
}

Why do they bind the namespaces to the IoC, when you can do App::make to get it anyway without binding these namespaces? I thought that I understood how that business works until I saw this piece of code.

Why did they do that? Thanks!

Answer 1

For example, u want to use some file storage in your aplication

App::bind( 'MyApp/FileStorage', function(){
    return new AmazonFileStorage;
});

Or

App::bind( 'MyApp/FileStorage', 'AmazonFileStorage');

First parameter for the bind method is a unique id to bind to the container, the second parameter is callback function to be executed each time we resolve the FileStorage class, we can also pass a string representing class name.

So maybe later you want to use other file storage service. You will need only to change your binding as in your application u will use "MyApp/FileStorage"

App::bind( 'MyApp/FileStorage', 'SystemFileStorage');

In this case

$this->app->bind(
  'Illuminate\Contracts\Auth\Registrar',
  'App\Services\Registrar'
);

There is interface Registrar :

<?php namespace Illuminate\Contracts\Auth;

interface Registrar {

/**
 * Get a validator for an incoming registration request.
 *
 * @param  array  $data
 * @return \Illuminate\Contracts\Validation\Validator
 */
public function validator(array $data);

/**
 * Create a new user instance after a valid registration.
 *
 * @param  array  $data
 * @return User
 */
public function create(array $data);

}

And service Registrar

<?php namespace App\Services;

use App\User;
use Validator;
use Illuminate\Contracts\Auth\Registrar as RegistrarContract;

class Registrar implements RegistrarContract {

/**
 * Get a validator for an incoming registration request.
 *
 * @param  array  $data
 * @return \Illuminate\Contracts\Validation\Validator
 */
public function validator(array $data)
{
    return Validator::make($data, [
        'name' => 'required|max:255',
        'email' => 'required|email|max:255|unique:users',
        'password' => 'required|confirmed|min:6',
    ]);
}

/**
 * Create a new user instance after a valid registration.
 *
 * @param  array  $data
 * @return User
 */
public function create(array $data)
{
    return User::create([
        'name' => $data['name'],
        'email' => $data['email'],
        'password' => bcrypt($data['password']),
    ]);
}

}

And then in 'App\Http\Controllers\Auth\AuthController' is injected

And the concept behind this is "Binding Interfaces To Implementations" You can read about it in official laravel 5 documantation http://laravel.com/docs/5.0/container#binding-interfaces-to-implementations and if it doesn't help, ask :)