README

This is a simple implementation of the standard container interface, with support for autowiring.

This means that this package will attempt to figure out all your basic dependencies for you. It also supports manually defining dependencies in a YAML file, or even adding service providers for more complex dependencies.

Installation

This package requires at least PHP 7.2.

Install it using composer:

composer require gdetassigny/simple-container

How to use it

Basic usage

Setting up a basic container is quite simple:

use GabrielDeTassigny\SimpleContainer\ContainerProvider;

$container = (new ContainerProvider())->getContainer();

That's it! You can now request your dependencies from the container, thanks to autowiring.

$container->get(Foo\Bar::class); // returns an instance of Foo\Bar

Autowiring

The container will be able to instantiate simple services which have straightforward dependencies in their constructors:

The below examples can all be autowired:

$container = (new ContainerProvider())->getContainer();

class NoConstructor {}

$container->get(NoConstructor::class);

class ConstructorNoParam {
    public function __construct() {}
}

$container->get(ConstructorNoParam::class);

class ConstructorWithClassParam {
    public function __construct(stdClass $param) {}
}

// Note: $param will be also instantiate and injected in the constructor
$container->get(ConstructorWithClassParam::class);

class ConstructorWithDefaultParam {
    public function __construct(?string $test = null) {}
}

// Note: parameters with default values will be set to these values when autowired
$container->get(ConstructorWithDefaultParam::class);

Some cases cannot be autowired:

$container = (new ContainerProvider())->getContainer();

class ConstructorWithPrimitiveParam {
    public function __construct(string $test) {}
}

// Fails! Autowiring cannot figure out the value of the $test parameter.
// Consider using a service provider
$container->get(ConstructorWithPrimitiveParam::class);

interface FooInterface {}
class Bar implements FooInterface {}

// Fails! Autowiring does not know which concrete class you want
// Consider using either a YAML Config or a service provider 
$container->get(FooInterface::class);

YAML Config

Simple container also supports adding a YAML config to manually define dependencies.

This can be useful to define a concrete class implementation of an interface. Or you may want to define a different name for your service than its class name.

dependencies:
  Foo\Bar:
    name: Foo\BarInterface
  
  Foo\Baz:
    name: some-id
    dependencies:
      - Foo\BarInterface

Simply pass the path of the YAML file to the container provider:

use GabrielDeTassigny\SimpleContainer\ContainerProvider;

$container = (new ContainerProvider('/path/to/config.yaml'))->getContainer();

$container->get(Foo\BarInterface::class); // returns an instance of Foo\Bar
$container->get('some-id'); // returns an instance of Foo\Baz

Service Provider

If a service requires a more complex setup, you may want to look at using a service provider.

use GabrielDeTassigny\SimpleContainer\ServiceProvider;
use GabrielDeTassigny\SimpleContainer\ContainerProvider;

class FooServiceProvider implements ServiceProvider
{
    public function getService(): object
    {
        return new Foo('some-string');
    }
}

$containerProvider = new ContainerProvider();
$containerProvider->registerService(Foo::class, new FooServiceProvider());

$container = $containerProvider->getContainer();

$container->get(Foo::class); // returns the instance of Foo defined in FooServiceProvider

Ordering

When called, the container will look for your service using all 3 above options in that order:

service provider
YAML config
autowiring

Why use this instead of another container package?

To be honest? Maybe you shouldn't. I built this mostly out of interest to understand how containers work under the hood. There are a lot of more evolved PHP containers out there.

However, I tried to make this package as straightforward to use as possible. If having a container up and running very quickly appeals to you then feel free to give this a go!

Furthermore, as it respects the standard container interface, you can always try it for a bit and later switch to another container package without too much hassle.

gdetassigny / simple-container

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