README

A lightweight PHP Dependency Injection Container implementing the PSR-11 standard. This library is designed for simplicity and ease of use, making it an ideal choice for small projects where you need a quick and effective DI solution.

Installation

composer require phpdevcommunity/psr11-dependency-injection

Usage

1. Define Your Services

Create a services.php file where you can define the parameters and services your application needs:

<?php

use Psr\Container\ContainerInterface;

return [
    'database.host' => '127.0.0.1',
    'database.port' => null,
    'database.name' => 'my_database',
    'database.user' => 'root',
    'database.password' => null,
    'google.key' => 'YQ4FcwaXD165Xm72lx53qzzNzkz7AUUN',
    PDO::class => static function (ContainerInterface $container) {
        return new PDO(
            sprintf('mysql:host=%s;dbname=%s;', $container->get('database.host'), $container->get('database.name')),
            $container->get('database.user'),
            $container->get('database.password'),
            [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]
        );
    },
];

2. Create and Use the Container

Instantiate the Container class with your service definitions and retrieve your services:

<?php

use PhpDevCommunity\DependencyInjection\Container;

$services = require 'services.php';
$container = new Container($services);

// Retrieve the PDO instance
$pdo = $container->get(PDO::class);
var_dump($pdo); // Outputs: object(PDO)[18]

// Retrieve a simple configuration value
$googleKey = $container->get('google.key');
var_dump($googleKey); // Outputs: YQ4FcwaXD165Xm72lx53qzzNzkz7AUUN

3. Autowiring

This library includes support for autowiring, allowing the container to automatically resolve class dependencies without the need for manual service definitions. The ReflectionResolver class leverages PHP’s Reflection API to inspect the constructor of a class and inject the necessary dependencies.

Example: Using Autowiring

<?php

use PhpDevCommunity\DependencyInjection\Container;
use PhpDevCommunity\DependencyInjection\ReflectionResolver;
use App\Service\MyService;

$services = require 'services.php';
$container = new Container($services, new ReflectionResolver());

// Automatically resolve MyService and its dependencies
$myService = $container->get(MyService::class);
var_dump($myService); // Outputs: object(MyService)

4. Variable Replacement in Configuration

This container also supports the replacement of variables in configuration values. This is useful when you want to store environment-specific settings, like database credentials, that can reference other configuration parameters. You can define variables in your configuration files that are automatically replaced when the container retrieves a service.

Example: Variable Replacement

<?php

use Psr\Container\ContainerInterface;

return [
    'database.host' => '127.0.0.1',
    'database.port' => '3306',
    'database.user' => 'root',
    'database.dsn'  => 'mysql://${database.user}@${database.host}:${database.port}/mydb',
];

In this example, the database.dsn value contains references to other configuration keys. When you retrieve this value from the container, the variables are automatically replaced with their corresponding values, resulting in the correct dsn for connecting to the database:

<?php

use PhpDevCommunity\DependencyInjection\Container;

$services = require 'services.php';
$container = new Container($services);

// Retrieve the database DSN with variables replaced
$dsn = $container->get('database.dsn');
echo $dsn; // Outputs: mysql://root@127.0.0.1:3306/mydb

This makes it easy to manage complex configurations that depend on other configuration values.

Contributing

Contributions are welcome! Feel free to open issues or submit pull requests to help improve the library.

License

This library is open-source software licensed under the MIT license.

phpdevcommunity / psr11-dependency-injection

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