how to use an autoloader in php - php

Question

I'm new to PHP and not really familiar with using git.
I got this library:
https://github.com/CKOTech/checkout-php-library
and I wanna run the sample code here:
https://github.com/CKOTech/checkout-php-library/wiki/Tokens
I know the code may not work perfectly for you cuz you would need a secret key from the provider, however, I don't need general errors like " cannot find class ApiClient"
what I did is simply including the autoloader in my index.php file, is that all what I have to do to use an Autoloader? does it have to do anything with composer.json?
Thanks a ton for the help in advance.
Autoloader.php:
<?php
function autoload($className)
{
$baseDir = __DIR__;
$realClassName = ltrim($className, '\\');
$realClassName = str_replace('\\',DIRECTORY_SEPARATOR,$realClassName );
$fileName = '';
$includePaths = $baseDir.DIRECTORY_SEPARATOR.$realClassName. '.php';
if ( $file = stream_resolve_include_path($includePaths) ) {
if (file_exists($file)) {
require $file;
}
}elseif(preg_match('/^\\\?test/', $className)) {
$fileName = preg_replace('/^\\\?test\\\/', '', $fileName);
$fileName = 'test' . DIRECTORY_SEPARATOR . $fileName;
include $fileName;
} else {
$classNameArray = explode('_', $className);
$includePath = get_include_path();
set_include_path($includePath);
if (!empty($classNameArray) && sizeof($classNameArray) > 1) {
if (!class_exists('com\checkout\packages\Autoloader')) {
include 'com'.DIRECTORY_SEPARATOR.'checkout'.DIRECTORY_SEPARATOR.'packages'.DIRECTORY_SEPARATOR.'Autoloader.php';
}
}
}
}
spl_autoload_register('autoload');

Answer 1

If you want to use an autoloader to make your life measurably better:
Use namespaces/PSR4.
Use Composer.
So let's say I'm working on project foo, within my working directory [let's just say it's /] I make a folder named /src/ and inside is /src/FooClient.php. It contains:
<?php
namespace sammitch\foo;
class FooClient {}
While in / I run composer init and accept all of the defaults, because typing out the simple JSON config file that that generates is tedious. Now I have a composer.json that looks like:
{
"name": "Sammitch/foo",
"authors": [
{
"name": "Sammitch",
"email": "sammitch#sam.mitch"
}
],
"require": {}
}
All we need to do now is add a section to the end:
"autoload": {
"psr-4": {
"sammitch\\foo\\": "src/"
}
}
Now to make Composer do it's magic and make the autoloader just run composer dumpautoload. When this runs Composer will create the /vendor/ folder and the autoloader.
Now all we need to do is:
<?php
require('vendor/autoload.php');
use \sammitch\foo\Client as FooClient()
$c = new FooClient();
Now not only do you have a top-tier autoloader, but you're also set up to start using Composer packages and leveraging all that good stuff from Packagist.