woocommerce-paypal-payments/bootstrap.php

<?php
/**
 * Bootstraps the modular app.
 *
 * @package WooCommerce\PayPalCommerce
 */

use Dhii\Container\CachingContainer;
use Dhii\Container\CompositeCachingServiceProvider;
use Dhii\Container\CompositeContainer;
use Dhii\Container\DelegatingContainer;
use Dhii\Container\ProxyContainer;
use Dhii\Modular\Module\ModuleInterface;
use Interop\Container\ServiceProviderInterface;
use Psr\Container\ContainerInterface;

return function (
	string $root_dir,
	ContainerInterface ...$additional_containers
): ContainerInterface {
	$modules = ( require "$root_dir/modules.php" )( $root_dir );

	// Use this filter to add custom module or remove some of existing ones.
	// Modules able to access container, add services and modify existing ones.
	$modules = apply_filters( 'woocommerce_paypal_payments_modules', $modules );

	$providers = array_map(
		function ( ModuleInterface $module ): ServiceProviderInterface {
			return $module->setup();
		},
		$modules
	);

	$provider        = new CompositeCachingServiceProvider( $providers );
	$proxy_container = new ProxyContainer();
	$container       = new DelegatingContainer( $provider, $proxy_container );
	$app_container   = new CachingContainer(
		new CompositeContainer(
			array_merge(
				$additional_containers,
				array( $container )
			)
		)
	);
	$proxy_container->setInnerContainer( $app_container );

	foreach ( $modules as $module ) {
		/* @var $module ModuleInterface module */
		$module->run( $app_container );
	}

	return $app_container;
};