init.php

<?php
/**
 * Initialize plugin functionality
 *
 * @package    Site_Core
 * @subpackage Init
 * @category   Core
 * @since      1.0.0
 */

namespace SiteCore;

// Alias namespaces.
use SiteCore\Classes\Autoload as Autoload;

// Restrict direct access.
if ( ! defined( 'ABSPATH' ) ) {
	die;
}

// Autoload classes.
require_once SCP_PATH . 'includes/classes/autoload.php';
Autoload\classes();

// Load required files.
foreach ( glob( SCP_PATH . 'includes/core/*.php' ) as $filename ) {
	require $filename;
}
foreach ( glob( SCP_PATH . 'includes/settings/*.php' ) as $filename ) {
	require $filename;
}
foreach ( glob( SCP_PATH . 'includes/media/*.php' ) as $filename ) {
	require $filename;
}
foreach ( glob( SCP_PATH . 'includes/network/*.php' ) as $filename ) {
	require $filename;
}
foreach ( glob( SCP_PATH . 'includes/backend/*.php' ) as $filename ) {
	require $filename;
}
foreach ( glob( SCP_PATH . 'includes/frontend/*.php' ) as $filename ) {
	require $filename;
}
foreach ( glob( SCP_PATH . 'includes/widgets/*.php' ) as $filename ) {
	require $filename;
}
foreach ( glob( SCP_PATH . 'includes/users/*.php' ) as $filename ) {
	require $filename;
}
foreach ( glob( SCP_PATH . 'includes/tools/*.php' ) as $filename ) {
	require $filename;
}
foreach ( glob( SCP_PATH . 'includes/vendor/*.php' ) as $filename ) {
	require $filename;
}

// Instantiate classes & define functions.
Settings\setup();
Core\setup();
Tools\setup();
Media\setup();
Widgets\setup();
Vendor\setup();
Users\setup();
User_Roles\setup();
Front_Page_Post_Type\setup();
Compatibility\setup();

// Network.
if ( is_multisite() ) {
	Network\setup();
}

// Front end.
if ( ! is_admin() ) {
	Front\setup();
	Meta_Tags\setup();
}

// Back end.
if ( is_admin() ) {
	Admin\setup();
	Admin_Footer\setup();
}