Nguyễn Khánk's Wiki

# PHP Autoloading

# PSR-4 Autoloader (opens new window)

PSR-4 describes a specification for autoloading classes from file paths.

# Take a tour

Let see how I use PRS-4 in webportal:

Definition: Add pieces of code into composer.json at root project.

"autoload": {
  "psr-4": {
    // more code ...
    "Wp3Module\\": "application/modules/",
    "Wp3\\": "application/",
    // more code ...
  }
}

Explanation:

  • the classes of namespace Wp3Module will be looked up and loaded at application/modules/
  • the classes of namespace Wp3 will be looked up and loaded at application/modules/

Run command in terminal:

composer dump-autoload

make sure you have installed the composer in your machine before you run

Then you can see few files in vendor update. It means Composer generates list of all classes that need to be included (autoload_classmap.php).

# Class definition

Create a file at /application/modules/contact/myfolder/Greeting.php with contents:


 




















<?php
namespace Wp3Module\contact\myfolder;

class Greeting 
{
    public static function getInstance() 
    {
		static $instance = null;
		if (null === $instance) {
			$instance = new static();
		}
		return $instance;
    }
    
	protected function __construct() {}

    function helloWorld() 
    {
        return 'Hello world';
    }
}

# Class Usage

Now you can use the class Greeting everywhere in our project. Create a controller /application/modules/contact/controllers/Hello_controller.php


 





 



<?php
use Wp3Module\contact\myfolder\Greeting;

class Hello_controller extends MX_Controller
{
    function index() 
    {
        echo Greeting::getInstance()->helloWorld();
    }
}

Open link to manual check: {webportal_url}/contact/hello_controller

# Conclusion

I just introduce to you:

  • Defining namespace & usage.
  • PSR-4 Autoloader with Composer.

We're more independent of Codeigniter

  • have our own directory structure.
  • easy to resolve dependencies I'll talk later in another post

# Other loaders with Composer

  • PRS-0: a older standards was replaced by PRS-4 - Not recommended
  • classmap: composer will scan all classes in given folder to build - Not recommended
  • files: point the specific files to load - useful for helpers

# References