Autoloading PSR-4 Standard

Because I blog about PSR-0!

Why new autoloading standard?

The reason is to simplify the creation of directory structure. Let's say I am creating a package jessiesiat/magic and we will use PSR-4 to autoload our classes.

But first let us see on how it is done using PSR-0.

Using PSR-0 ​

starting with the composer.json

...
{
	"autoload": {
		"psr-0": {
			"JessieSiat\\Magic\\": "src/"
		}
	}
}
...

our directory structure would be - pay attention to the hierarchy

/src
	/JessieSiat
		/Magic
			Card.php
/test
..
composer.json
..

then our Card.php file definition

<?php namespace Jessiesiat\Magic;

class Card {

	// function definition here

}

Were done, our class 'JessieSiat\Magic\Card' now exists!

At some point it is not neccessary to have that kind of directory structure. Why not define the classes directly under the src/, especially if you just need few classes. We can achieve that with PSR-4, using the same namespace as above.

Using PSR-4 ​

as said, this is how our directory looks like

/src
	Card.php
	..
/test
..
composer.json
..

our Card.php file definition would be the same - see namespace keyword

<?php namespace Jessiesiat\Magic;

class Card {

	// function definition here

}

then our composer.json would be.

...
{
	"autoload": {
		"psr-4": {
			"JessieSiat\\Magic\\": "src/"
		}
	}
}
...

After running composer dump-autoload our class 'JessieSiat\Magic\Card' now exists, simplifying our directory!

More info here