IoC bindings in Laravel

foo.php

<?php namespace Acme;

interface IFoo {}

class Foo implements IFoo {}

class Bar {
  public function __construct(\Acme\IFoo $foo) {}
}

class Baz {
  public function __construct(\Acme\Foo $foo) {}
}

/** @type \Illuminate\Foundation\Application $app */
$app->singleton('foo', function(){ return new \Acme\Foo; });

/**
  * As I mapped my \Acme\Foo to the 'foo' string, some DI stuff won't work.
  * This is because of how the container resolves classes and interfaces.
  */

// Works because Foo is concrete and doesn't have dependencies
$foo = $app->make(Acme\Foo::class); 

// Doesn't work, the interface was never bound to an implementation
// "Acme\IFoo is not instantiable" or something...
$anyFoo = $app->make(Acme\IFoo::class);

// Doesn't work because the container can't resolve IFoo
$bar = $app->make(Acme\Bar::class);

// Works because the container can resolve concretes automatically
$baz = $app->make(Acme\Baz::class);

/**
  * Adding the interface binding would solve all of this.
  */
$app->bind(Acme\IFoo::class, Acme\Foo::class);

// new Foo;
$anyFoo = $app->make(Acme\IFoo::class);

// new Bar( new Foo );
$bar = $app->make(Acme\Bar::class);

laravel-stuff.php

<?php namespace Acme;

/** Try some of this examples: */

// AuthManager is bound to $app['auth']
class MyAuthAdapter {
  public $auth;
  public function __construct(AuthManager $auth){ $this->auth = $auth; }
}

// gets the current user (the facade uses $app['auth'])
Auth::getUser();

// Fails to get the current user, as its not a singleton service
App::make(\Acme\MyAuthAdapter::class)->auth->driver()->getUser();


class ValidationAwareStuff {
  private $validator;
  public function __construct(\Illuminate\Validation\Validator $validator){
    $this->validator = $validator;
  }
}

// Will fail, TranslatorInterface is not bound
App::make(ValidationAwareStuff::class);

// But the validation factory has a default one tho...
$validator = Validator::make(['some' => 'rules'], ['some' => 'data']);