wp-class-autoloader

wp-class-autoloader.php

<?php
if ( ! defined( 'WPINC' ) ) {
	die;
}

/**
 * Class autoloader
 *
 * @param  string $class Qualified class name.
 */
function xx_class_autoloader( $class ) {
	
	// If the $class_name does not include our theme's namespace, GTFO.
	if ( false === strpos( $class, 'Theme_Name' ) ) {
		return;
	}
	$namespace_parts = explode( '\\', $class );
	
	// Format parts to match filenames.
	$file_parts = array_map( function( $part ) {
		return str_replace( '_', '-', strtolower( $part ) );
	}, $namespace_parts );
	$class_path = get_template_directory() . '/inc/classes/';
	
	// If class uses sub-namespaces, we'll stick them in matching sub-directories.
	if ( count( $file_parts ) > 2 ) {
		// Remove first array item (theme namespace) and last array item (filename).
		// Anything in between will go in the path.
		$class_path .= implode( DIRECTORY_SEPARATOR, array_slice( $file_parts, 1, count( $file_parts ) - 2 ) ) . '/';
	}
	
	// Construct file path + name.
	$file = $class_path . 'class-' . end( $file_parts ) . '.php';
	
	if ( file_exists( $file ) ) {
		require_once $file;
	} else {
		echo "GTFO: `{$file}` does not exist.<br />";
	}
}

spl_autoload_register( 'xx_name_autoloader' );

This autoloader looks for class files stored in the theme directory inc/classes that are properly namespaced using Theme_Name, and sotring classes with sub-namespaces in subdirectories.

Example: Theme_Name\Display_Classes\Render_Content would be loaded from inc/classes/display-classes/class-render-content.php.