Container

A container is a data structure whose instances are collections of other objects. Containers store objects in an organized way that follows specific access rules.

Example Concept

For this concept on containers, kindly check the code below on how to implement a class with a constructor:

class Foo
{
    public function baz()
    {
        // ...
    }
}

class Bar
{
    protected $foo;

    public function __construct(Foo $foo)
    {
        $this->foo = $foo;
    }

    public function booz()
    {
        return $this->foo->baz();
    }
}

$bar = new Bar(new Foo);

With the example code above, the Bar class must always have an instance of Foo.

Example Code

To use the Bar class, it needs to be implemented again like in the example code above which can be cumbersome. One of the solutions for this is to store it into a container once so it can be accessed anywhere in the application code:

use Rougin\Slytherin\Container\Container;

$container = new Container;

$bar = new Bar(new Foo);

$container->set('Bar', $bar);

// Returns an instance of Bar ---
$new = $container->get('Bar');
// ------------------------------

Third-party implementations

Some third-party packages for container provide additional functionalities like auto-wiring dependencies and more. With this, Slytherin supported the following third-party packages that can be integrated seamlessly to Slytherin core once their respective packages were installed:

• AurynContainer - uses the Auryn package by Daniel Lowrey (rdlowrey/auryn)
• LeagueContainer - uses the Container package from The PHP League (league/container)

If not using the supported packages above, a list of packages that implements the dependency injection design pattern are also listed at the awesome-php repository. Once selected a specified package, it must be implemented in ContainerInterface:

namespace Rougin\Slytherin\Container;

use Psr\Container\ContainerInterface as PsrContainerInterface;

interface ContainerInterface extends PsrContainerInterface
{
    /**
     * Sets a new instance to the container.
     *
     * @param  string $id
     * @param  mixed  $concrete
     * @return self
     */
    public function set($id, $concrete);
}