Composer Autoloading

Key Points

• +PSR-4 autoloading - Modern standard der mapper namespaces til directories
• +Classmap - Pre-computed map af alle klasser for hurtigere loading
• +Files autoloading - Inkluder specific files (helpers, functions) automatisk
• +Optimize autoloader - Generér classmap for production performance
• +composer dump-autoload - Regenerér autoloader efter ændringer
• +Namespace mapping - Definer root namespace til directory mapping i composer.json
• +Development vs production - Forskellige optimization strategies
• +Autoload-dev - Separate autoload config til development/testing
• +vendor/autoload.php - Single entry point der skal inkluderes
• +Class not found errors - Troubleshooting når autoloading fejler

Kode Eksempel

<?php

// composer.json configuration
// {
//   "autoload": {
//     "psr-4": {
//       "App\\": "src/",
//       "Database\\": "database/"
//     },
//     "files": [
//       "src/helpers.php"
//     ],
//     "classmap": [
//       "legacy/"
//     ]
//   },
//   "autoload-dev": {
//     "psr-4": {
//       "Tests\\": "tests/"
//     }
//   }
// }

// File: src/Models/User.php
namespace App\Models;

class User {
    public function __construct(
        public string $name,
        public string $email
    ) {}
    
    public function getDisplayName(): string {
        return ucfirst($this->name);
    }
}

// File: src/Services/UserService.php
namespace App\Services;

use App\Models\User;

class UserService {
    private array $users = [];
    
    public function create(string $name, string $email): User {
        $user = new User($name, $email);
        $this->users[] = $user;
        return $user;
    }
    
    public function getAll(): array {
        return $this->users;
    }
}

// File: src/helpers.php (loaded automatically via files autoload)
function app_url(string $path = ''): string {
    return 'https://example.com/' . ltrim($path, '/');
}

function config(string $key, mixed $default = null): mixed {
    // Load configuration value
    return $default;
}

// File: public/index.php
require __DIR__ . '/../vendor/autoload.php';

use App\Models\User;
use App\Services\UserService;

// No need for require statements - classes are autoloaded
$userService = new UserService();
$user = $userService->create('John Doe', 'john@example.com');

echo $user->getDisplayName() . PHP_EOL;
echo app_url('dashboard') . PHP_EOL; // Helper from files autoload

// Running: composer dump-autoload
// Regenerates the autoloader with all mappings

Best Practices

• +Følg PSR-4 standard strengt - ét namespace segment per directory niveau
• +Run 'composer dump-autoload -o' (optimize) i production for classmap generation
• +Placer vendor/autoload.php require som første statement i din application
• +Brug autoload-dev for test classes og development-only kode
• +Avoid mixing PSR-4 og classmap unless necessary for legacy support
• +Commit composer.lock til version control for reproducible builds
• +Run composer dump-autoload efter at tilføje nye classes eller ændre struktur
• +Organize kode i src/ directory og map det til dit root namespace i composer.json