Container Laravel Package

Getting Started

Start by installing the package via Composer (composer require illuminate/container) or using it within a Laravel app (it’s bundled in laravel/framework). Begin with resolving a simple class:

$container = new Illuminate\Container\Container();
$container->bind(\Psr\Log\LoggerInterface::class, \App\Logging\ConsoleLogger::class);
$logger = $container->make(\Psr\Log\LoggerInterface::class);

Explore the API by checking bind(), singleton(), instance(), make(), and resolve() — these cover 90% of day-to-day usage. Use Container::getInstance() only when globally sharing a single container instance.

Implementation Patterns

• Interface Binding + Resolving: Bind interfaces to concrete types to decouple logic and enable testing (e.g., bind(NotificationSenderInterface::class, SlackSender::class)). Resolve them anywhere via make() or constructor injection.
• Contextual Binding: Use when(...)->needs(...)->give(...) to inject different implementations based on consumer class (e.g., production vs. staging storage for a StorageInterface in UploadController vs. ImportController).
• Tagging for Plugins or Lists: Tag related bindings ($container->tag('formatter', [JsonFormatter::class, XmlFormatter::class])) and resolve all at once ($container->tagged('formatter')), ideal for extension points like event listeners or formatters.
• Method Injection via call(): Resolve dependencies dynamically for callbacks (e.g., $container->call([$controller, 'index'])) — crucial for event dispatching, CLI commands, and custom routing.
• Extending Bindings Post-Resolution: Use extend() to wrap resolved services (e.g., add logging, caching, or retries) without modifying the original class:

  $container->extend(ApiClient::class, function ($client, $container) {
      return new RetryDecorator($client);
  });
  

Gotchas and Tips

• Avoid modifying the global instance: Container::setInstance() affects the entire process — dangerous in CLI workers (e.g., Horizon, queue listeners). Prefer local containers or explicit instantiation unless resetting context intentionally.
• Circular dependency detection is runtime-only: If A injects B and B injects A, you’ll get a CircularDependencyException at resolve time — prevent by injecting interfaces, using lazy proxies, or deferring with make() in the constructor.
• Parameterized resolution: Use makeWith() or contextual needs('$variable')->give($value) when constructor parameters aren’t type-hinted or vary at runtime (e.g., injecting a config key or dynamic ID).
• PSR-11 compatibility ≠ feature parity: While it implements Psr\Container\ContainerInterface, Laravel-specific methods like tag(), extend(), build() won’t work outside Laravel — avoid relying on them for portability.
• Debug resolution state: resolved($abstract) tells if a binding is already instantiated, and build() lets you inspect how a class would be resolved (useful for debugging missing bindings or double resolution).
• Extensibility hooks: Register callbacks via resolver or override make() / build() for cross-cutting concerns (e.g., auto-instrumentation, lazy-loading proxies, or DI tracing).