使用Composer解决依赖注入：PSR-11容器接口的应用

composer require psr/container

use Psr\Container\ContainerInterface;

class MyService
{
    private $dependency;

    public function __construct(DependencyInterface $dependency)
    {
        $this->dependency = $dependency;
    }

    public function doSomething()
    {
        // 使用依赖做一些事情
    }
}

class MyContainer implements ContainerInterface
{
    private $entries = [];

    public function get($id)
    {
        if (!$this->has($id)) {
            throw new NotFoundException('No entry was found for this identifier.');
        }
        return $this->entries[$id];
    }

    public function has($id)
    {
        return isset($this->entries[$id]);
    }

    public function set($id, $value)
    {
        $this->entries[$id] = $value;
    }
}

$container = new MyContainer();
$container->set(DependencyInterface::class, new ConcreteDependency());

$myService = new MyService($container->get(DependencyInterface::class));
$myService->doSomething();