README

takaram/nano-di is a tiny PSR-11 dependency injection container for PHP.

It is intentionally small: no configuration DSL, no attributes, no service providers, and no compile step. In return, it gives you a lightweight container that can resolve ordinary constructor-injected objects with very little setup.

Installation

composer require takaram/nano-di

Requirements

• PHP 8.3 or later
• psr/container 2.0

Quick Start

<?php

declare(strict_types=1);

use App\Repository\UserRepository;
use Psr\Container\ContainerInterface;
use Takaram\NanoDi\Container;

final class UserService
{
    public function __construct(
        private UserRepository $users,
    ) {}
}

$container = new Container();

$service = $container->get(UserService::class);

var_dump($service instanceof UserService); // true
var_dump($container instanceof ContainerInterface); // true

When a constructor parameter has a concrete class type, or a mapped interface type, nano-di resolves that dependency recursively.

Interface Mappings

Pass a simple map to bind an interface or abstract service id to a concrete class:

<?php

declare(strict_types=1);

use App\Contract\Mailer;
use App\Service\SmtpMailer;
use App\Service\UserNotifier;
use Takaram\NanoDi\Container;

$container = new Container([
    Mailer::class => SmtpMailer::class,
]);

$notifier = $container->get(UserNotifier::class);

In this example, if UserNotifier depends on Mailer, nano-di will instantiate SmtpMailer.

What It Does

• Implements Psr\Container\ContainerInterface
• Resolves concrete classes by class name
• Resolves constructor dependencies recursively
• Supports interface-to-class mappings through a plain array
• Reuses resolved objects for subsequent get() calls
• Uses default values for builtin constructor parameters when available
• Throws PSR-11 compatible exceptions for missing entries and container failures

What It Leaves Out

nano-di is built for small applications, tests, CLIs, examples, and libraries that only need a minimal container. The current API deliberately leaves out larger container features such as:

• Factory callbacks
• Runtime parameters
• Attributes or annotations
• Autowiring rules beyond constructor type hints
• Service scopes
• Lazy proxies
• Compilation or caching layers

If your project needs those features, a full-featured DI container may be a better fit. If you only need constructor autowiring and a few interface mappings, nano-di keeps the moving parts low.

Development

Install dependencies:

composer install

Run the test suite and checks:

composer test
composer phpstan
composer cs:check

License

MIT