Autoload and Namespaces in PHP

I will correct all my answer among other things, because I confused the% namespace with use «Question of copy-paste»

Let's take your example:

define("PROJECTPATH", dirname(__DIR__));

spl_autoload_register(function($class) {
    $filename = PROJECTPATH . '/App/Controller/' . $class . '.php';
    include_once $filename; 
});

use App\Controller\Usuario;
$var = new usuarioController();
echo $var->saludar(); 

When you use the line

use App\Controller\Usuario;

  

It's as if you told the interpreter "it matters {SOMETHING} that it's called App\Controller\Usuario and would like to give it a short alias like Usuario "

 //Este es el equivalente
 use App\Controller\Usuario as Usuario;

     

link

Considering how you define the class

namespace App\Controller\Usuario;

class usuarioController {
    function saludar() {
        echo "hola";
    }
}

The right thing to do is to import in this way

use App\Controller\Usuario\usuarioController;

The above solves the problem as to how you import, the detail is that you were misusing the% use . Now Once this has been resolved, let's go into another detail The path of the file that contains the definition of the class

spl_autoload_register(function($class) {
    $filename = PROJECTPATH . '/App/Controller/' . $class . '.php';
    include_once $filename; 
});
$var = new App\Controller\Usuario\usuarioController();

When executing this line

$var = new App\Controller\Usuario\usuarioController();

The interpreter will try to find the definition of the class you want to instantiate and when you do not find it will trigger the __autoload queue provided by spl, in simpler terms more or less «Execute the function you registered with the spl_autoload_register by passing it through parameter the full name of the class you want to instantiate, ie 'App \ Controller \ User \ userController' »

function($class) {
   $filename = PROJECTPATH . '/App/Controller/' . $class . '.php';
   include_once $filename; 
}
// Así $class = 'App\Controller\Usuario\usuarioController'
// Por tanto $filename = PROJECTPATH . '/App/Controller/App\Controller\Usuario\usuarioController.php'

Possibly you have already realized the failure, in windows whose delimiter by default of directories is '\' this would translate to a structure like this:

App
+-Controller
  +-App
    +-Controller
      +-Usuario
        +-usuarioController.php

Very different from what you have, right?

Possible solution

I think what you're trying is this

  

File: App / Controller / userController.php

<?php 
    namespace App\Controller;

    class usuarioController {
        function saludar() {
            echo "hola";
        }
    }

  

File to execute

<?php

    define("PROJECTPATH", dirname(__DIR__));

    spl_autoload_register(function($class) {
        $filename = PROJECTPATH . "/$class.php";
        include_once $filename; 
    });

    use App\Controller\usuarioController as Usuario;
    $usuario = new Usuario();
    echo $usuario->saludar();

Now this exposed above will only work in windons since looking for PROJECTPATH . '/App\Controller\usuarioController.php' this will interpret something like C:\...\App\Controller\usuarioController.php while in linux the situation will be somewhat different considering that the directory separator is '/' then .../App\Controller\usuarioController.php will not be interpreted as you would expect but more or less something like this:

App
   Controller\usuarioController.php //La barra invertida puede contituir parte del nombre

To correct this you must tell PHP to replace the '\' and '/' bars with the corresponding delimiter, like this:

spl_autoload_register(function($class) {
   $filename = PROJECTPATH . "/$class.php";
   $filename_real = str_replace(['/',"\"],DIRECTORY_SEPARATOR,$filename);
   include_once $filename_real; 
});

To be more didactic I have shown it in an extra line

$filename_real = str_replace(['/',"\"],DIRECTORY_SEPARATOR,$filename);