Simple DI Container

A tiny, reflection-based Dependency Injection container with zero external dependencies. It supports constructor autowiring for class-typed dependencies and simple manual bindings via callables.

Requirements

• PHP 8.2+
• Composer (for autoloading)

Installation

Clone the repository and install the Composer autoloader (no packages are required, but autoload files will be generated if needed):

git clone git@github.com:innerfly/Simple-DI-container.git
cd Simple-DI-container
composer install

Usage example

<?php
require __DIR__ . '/vendor/autoload.php';

use App\Container;

$container = new Container();

// 1) Auto-wiring by constructor type-hints
class Logger {
    public function log($message){
        echo $message;
    }
}

class Service {
    public function __construct(public Logger $logger) {}
}

$service = $container->get(Service::class);
$service->logger->log('Hello world!');

// 2) Manual binding via callable (factory semantics: new instance each time)
$container->set('now', fn() => new DateTimeImmutable());

echo($container->get('now')->format('Y-m-d H:i:s'));

Notes:

• Lazy loading: Services (and their nested dependencies) are not instantiated until you call get(). The container caches only the resolver (a closure); it does NOT cache created instances by default.
• Reflection is performed only once per key; subsequent get() calls reuse the cached resolver, keeping lazy loading efficient.