Feature: decorators

[xepozz]

Would be nice allow to decorate already existing services in container.
I see at least 2 variants of usage:

1. Decorating already existing service that exist in another container (applied only to CompositeContainer)
   // config/common.php

return [
  // ...
  LoggerInterface::class => function() use ($compositeContainer) {
    return new LoggerDecorator($compositeContainer->get(LoggerInterface::class));
  }
  // ...
];

At now it parsed as circle dependency, but we can modernize this syntax. At now it doesn't matter.
2. Decorating already existing services in current container
// config/common.php

return [
  // ...
  LoggerInterface::class => /* ... */,
  
  LoggerDecorator::class => [
      'decorated' => LoggerInterface::class
  ];
  // ...
];

or
// config/common.php

return [
  // ...
  LoggerInterface::class => /* ... */,
  // ...
];

// config/common.dev.php

return [
  // ...
  LoggerInterface::class => function ($container) {
      return new LoggerDecorator($container->get(LoggerInterface::class));
  }
  // ...
];

What is the expected result?

In all cases $container->get(LoggerInterface::class) should return LoggerDecorator

What do you get instead?

In the first case we have CircularReferenceException. In the second case we have LoggerInterface implementation that passed via /* ... */ or CircularReferenceException`.

Additional info

I think we need to think all future features for another cases (I'm not about decorators only).

[xepozz]

I made syntax examples.

LoggerInterface::class => (new ContainerBuilder())
  ->callback(fn () => new Logger())
  ->decorate(fn ($container, $logger) => new LoggerDecorator($logger));

LoggerInterface::class => (new ContainerBuilder())
  ->callback(fn () => new Logger())
  ->decorate(LoggerDecorator::class),
LoggerDecorator::class => fn ($container) => new LoggerDecorator($container->get(LoggerInterface::class)),

$definitions = [
  LoggerInterface::class => fn () => new Logger(),
  LoggerDecorator::class => fn ($container) => new LoggerDecorator($container->get(LoggerInterface::class)),
];
$containerBuilder
  ->decorate(LoggerInterface::class, LoggerDecorator::class)
  ->decorate(ContainerInterface::class, ContainerDecorator::class);

[viktorprogger]

#10

[viktorprogger]

Why do decorators better than nested/contextual containers?

[xepozz]

Using decorators we can to substitude any dependencies from PSR container, not only Yii container.
It looks more cleaner and flexible.
Nested container is a part of way to use decorators.

Do you have examples with contextual container that solve this problem?