Namespace in PHP CodeIgniter Framework

How To Get Namespaces to Work in Codeigniter

Actually, you can get namespaces to work in conjunction to relative paths in your application models. This modification makes loading models much easier and also allows you to have interfaces...

Add this to the end of your application/config/config.php

spl_autoload_extensions('.php'); // Only Autoload PHP Files

spl_autoload_register(function($classname) {
    if (strpos($classname,'\\') !== false) {
        // Namespaced Classes
        $classfile = strtolower(str_replace('\\', '/', $classname));

        if ($classname[0] !== '/') {
            $classfile = APPPATH.'models/' . $classfile . '.php';
        }               
        require($classfile);
    } elseif (strpos($classname, 'interface') !== false) {
        // Interfaces
        strtolower($classname);
        require('application/interfaces/' . $classname . '.php');
    }
});

Example Namespaced Class:

<?php
// File: application/models/foo/bar.php
namespace foo;

class Bar extends \CI_Model implements \Awesome_interface {

    public $foobar;

    public function __construct() {
        return parent::__construct();
    }

    public function getFoobar() {
        return $this->foobar;
    }

    public function setFoobar($val) {
        $this->foobar = $val;
    }

}

Example Instantiation of Class in Your Code Somewhere:

IMPORTANT NOTE: DO NOT USE BUILT IN CI_Loader ( Ex: $this->load->model(); )

// This will Autoload Your Namespaced Class
$example = new foo\Bar();

or alternatively on top of your PHP class (ex: controller, other model), you can do this...

<?php
...
use foo\Bar as FooBar;

...

// Then you can just do this
$example = new FooBar();

Example of Interface:

<?php
// File: application/interfaces/awesome_interface.php
interface Awesome_interface {

    public function getFoobar();

}

Just a simple psr-4 autoloading and you are done.

In the config/config.php load composer using

$config['composer_autoload'] = FCPATH.'vendor/autoload.php';

In the root directory run composer install In the generated composer.json add following lines for psr4 autoloading.

    "autoload": {
        "psr-4": {
            "App\\": "application/"
        }
    },  

App would be your namespace in this case.

Example: suppose you have a class Service in libraries folder. You can namespace it with:

<?php
namespace App\libraries;

class Service{
}

Use it in Welcome controller class:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

use App\libraries\Service;
class Welcome extends CI_Controller {
}

Namespace are supported by php and not by the framework (codeigniter in your case). If you use namespaces php version must be >= 5.3.0 Codeigniter dosen`t use namespaces because it is written to support php 4.