README

Quillstack DI Container is the dependency injection container based on PSR-11: Container interface, and with the main goal: to be fast. You can find the full documentation on the website:
https://quillstack.org/di

This DI container uses constructors and types of class properties.

Installation

To install this package, run the standard command using Composer:

composer require quillstack/di

Usage

You can use Quillstack DI Container when you want:

• To have a simple and fast DI container.
• Define dependencies based on interfaces.
• Define parameters e.g. credentials for a database in the Database class.
• To use constructors or/and class properties.
• To implement your own instance factories e.g. for Request classes.
• To use objects as dependencies.

Simple usage

You can easily start using a DI Container:

<?php

use Quillstack\DI\Container;

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

$container = new Container();
$controller = $container->get(ExampleController::class);

Where your ExampleController class looks like:

<?php

class ExampleController
{
    private $example = 3;
}

Dependencies based on interfaces

If you want to define which class should be loaded based on an interface:

$container = new Container([
    LoggerInterface::class => Logger::class,
]);
$controller = $container->get(ExampleController::class);

You can define your dependencies using interfaces:

<?php

class ExampleController
{
    public function __construct(
        private LoggerInterface $logger
    ) {
    }
}

When you create the object using the DI container, the type of $logger property will be set to Logger.

Dependencies with parameters

If some of your classes require parameters, define them as an array passed on the second parameter to the container:

$container = new Container([
    Database::class => [
        'hostname' => 'localhost',
    ],
]);
$controller = $container->get(ExampleController::class);

Every time you will get a database object, a container will use localhost as a value for $hostname parameter:

<?php

class Database
{
    public function __construct(
        private string $hostname
    ) {
    }
}

Custom instance factories

You can implement your own instance factory. This is especially useful when you want to create many objects in a class family that are very similar in some way.

In our example we want to create different request objects:

<?php

class CreateUserRequest implements RequestInterface
{
}

First, we had to create RequestInterface as a common interface for all requests.

Next, we have to create an instance factory class. To create it, extend a class with CustomFactoryInterface:

<?php

use Quillstack\DI\CustomFactoryInterface;

class RequestClassFactory implements CustomFactoryInterface
{
    /**
     * {@inheritDoc}
     */
    public function create(string $id): object
    {
        $factory = $this->container->get(GivenRequestFromGlobalsFactory::class);

        return $factory->createGivenServerRequest($id);
    }
}

Also, use this configuration array when you create a DI container:

$container = new Container([
    RequestInterface::class => RequestClassFactory::class,
]);
$controller = $container->get(ExampleController::class);

Custom factories are useful for objects you want to create similarly.

Dependencies as objects

In this example, whenever a new class of LoggerInterface will be required as a dependency, a container will use a previously defined object. This object can be created once in a bootstrap file and used in the entire application:

$logger = new Logger('name');
$logger->pushHandler(new StreamHandler('var/app.log'););

$container = new Container([
    LoggerInterface::class => $logger,
]);

This configuration is helpful if an object should be created once and its instance should be used in other places in the application.

Unit tests

Run tests using a command:

phpdbg -qrr ./vendor/bin/unit-tests

Docker

$ docker-compose up -d
$ docker exec -w /var/www/html -it quillstack_di sh