How to include a PHP class using namespaces - php

Question

I haven't quite got my head around namespaces in PHP yet. Nor do I use composer or autoloaders. I understand them, but often have difficulty including them into my own projects.
So I would like to include a package in a Wordpress plugin I am developing, specifically this one https://github.com/elliotboney/thinkific-php
I can include the main file OK, but get the error below when calling a function within that file. I am not sure if its to do with the fact its using namespaces, or just because its trying to include files in the Api sub folder which wont be the correct path once I include the main file into my own code.
Does anyone know how I can include this package to use it it within my own project?
require_once('Thinkific/Thinkific.php');
$think = new \Thinkific\Thinkific([
'apikey' => 'xxxxxxxxx',
'subdomain' => 'yyyyyyyyy',
'debug' => true
]);
$users = $think->users();
$users = $users->getAll();
But this is the error, which shows that the class files and so classes in the Api sub-folder are not loaded.
Fatal error: Uncaught Error: Class '\Thinkific\Api\Users' not found in Fatal error: Uncaught Error: Class '\Thinkific\Api\Users' not found in /mysite/public_html/wp-content/plugins/thinkific/Thinkific/Thinkific.php:51 Stack trace: #0 /mysite/public_html/wp-content/plugins/thinkific/Thinkific/Thinkific.php(36): Thinkific\Thinkific->getApi('\\Thinkific\\Api\\...') #1 /mysite/public_html/wp-content/plugins/thinkific/thinkific.php(50): Thinkific\Thinkific->__call('users', Array) #2 /mysite/public_html/wp-content/plugins/thinkific/thinkific.php(29): Thinkific::thinkific_get_users() #3 /mysite/public_html/wp-includes/class-wp-hook.php(298): thinkific_woocommerce_order_status_completed(Object(WP)) #4 /mysite/public_html/wp-includes/class-wp-hook.php(323): WP_Hook->apply_filters('', Array) #5 /mysite/public_html/wp-includes/plugin.php(515): WP_Hook->do_action(Array) #6 /mysite/public_html/wp-includes/class-wp.php(746): do_action_ref_array('wp in /mysite/public_html/wp-content/plugins/thinkific/Thinkific/Thinkific.php on line 51

Answer 1

Try something like this:
lib.php:
<?php
// Application library 1
namespace App\Lib1;
const MYCONST = 'Hello,';
// Application library 1
namespace App\Lib2;
const MYCONST = 'How are you?';
function MyFunction() {
return __FUNCTION__;
}
class MyClass {
static function WhoAmI() {
return __METHOD__;
}
}
?>
myapp.php:
<?php
require_once('lib.php');
echo App\Lib1\MYCONST . "\n";
echo App\Lib2\MYCONST . "\n\n";
echo App\Lib2\MyFunction() . "\n";
echo App\Lib2\MyClass::WhoAmI() . "\n";
?>

Answer 2

The library which you are using is dependent on composer, the place where you doing composer install there it will generate a vendor/autoload.php, you just need to generate vendor/autoload.php here this file will take care of your autoloading of classes.
require_once 'vendor/autoload.php';
$think = new \Thinkific\Thinkific([
'apikey' => 'xxxxxxxxx',
'subdomain' => 'yyyyyyyyy',
'debug' => true
]);
$users = $think->users();
$users = $users->getAll();