Smart loader for libraries in WordPress

smart-loader.php

<?php

use PPWPProPluginsAds\Autoloader;

if (file_exists(__DIR__ . '/vendor')) {
    require_once __DIR__ . '/vendor/autoload.php';
}

$version = '0.1.0';

if (!function_exists('calculatePriorityFromVersion')) {
    /**
     * This function requires the version in a semantic version format: 0.0.0(-[alpha|beta|rc].0)?
     *
     * Examples:
     *
     * 1.2.3-alpha.4 => 01 02 03 1 04 => 10,203,104
     * 10.20.30-alpha.40 => 10 20 30 1 40 => 102,030,140
     * 10.20.30-beta.40 => 10 20 30 1 40 => 102,030,240
     *
     * @see http://semver.org/
     *
     * @param string $version
     *
     * @return int
     */
    function calculatePriorityFromVersion($version)
    {
        $priority = 0;

        if (strpos($version, '-')) {
            // Has unstable version
            $parts            = explode('-', $version);
            $version          = $parts[0];
            $unstableVersion  = strtolower($parts[1]);
            $unstablePriority = 0;

            if (false !== strpos($unstableVersion, 'alpha')) {
                $unstablePriority += 100;
            } elseif (false !== strpos($unstableVersion, 'beta')) {
                $unstablePriority += 200;
            } elseif (false !== strpos($unstableVersion, 'rc')) {
                $unstablePriority += 300;
            }

            $unstableVersion = preg_replace('/(alpha|beta|rc)\./', '', $unstableVersion);

            $unstablePriority += (int)$unstableVersion;

            $priority += $unstablePriority;
        }

        $versions = explode('.', $version);

        $priority += (int)$versions[0] * 10000000;
        $priority += (int)$versions[1] * 100000;
        $priority += (int)$versions[2] * 1000;

        return $priority;
    }
}

$loadingPriority = PHP_INT_MAX - calculatePriorityFromVersion($version);

add_action('ppwppropluginsads_library_load', function () use ($version) {
    if (!defined('PPWPPROPLUGINSADS_LOADED')) {
        define('PPWPPROPLUGINSADS_VERSION', $version);

        if (!class_exists('PPWPProPluginsAds\\Autoloader')) {
            require_once __DIR__ . '/core/Autoloader.php';
        }

        Autoloader::register('PPWPProPluginsAds', __DIR__ . '/core');

        define('PPWPPROPLUGINSADS_LOADED', 1);
    }
}, $loadingPriority);

This only works for "predictable" implementations, so basically only on the libraries we have control. Can't protect us from other libraries loaded before we have the chance to load it.

Well, it seems like Jetpack already implemented a solution for this using an autolaoder for composer:

https://github.com/Automattic/jetpack-autoloader