Decoración: Anular los servicios del núcleo y AsDecorator

Thank you for the suggestions Vincent!

Hey @julien_bonnier!

That IS interesting! Hmm. So it's legal for a concrete implementation (e.g. EventDispatcher) to widen (i.e. allow more types) the arguments for a method from an interface. If the interface has callable $listener, it is legal for the concrete class to have callable|array $listener.

However, in practice this means that if someone ever calls ->addListener() and passes an array for the $listener argument, that "someone" should be type-hinting EventDispatcher and not EventDispatcherInterface. In other words, doing this would work, but you're kind of breaking the rules:

public function something(EventDispatcher $dispatcher)
{
    $dispatcher->dispatch('some_event', [$this, 'bar']);
}

The fact that you got this error makes me think that, in fact, something, somewhere is doing exactly that. The problem is that, wherever this is happening, if the type-hint changed from EventDispatcherInterface to EventDispatcher (so that it's more "honest"), that would totally break the ability to decorate the event dispatcher.

So... yes, something is "not right" here. But I'm not sure exactly what it is. It might simply be that, in reality, Symfony relies on $listener being able to be an array in some cases... and that the "bug" is that we need this... but we haven't make the $listener argument in the interface match this reality. I can't locate the history in Symfony where this changed, so I don't know if this was intentional or accidental. Interesting!

Cheers!

Not sure if you know about this GitHub issue. Seems like an issue that is likely to keep coming up.

Hey Ruslan,

Thank you for your feedback! It may happen in the future ;) For now, we're focusing on other topics :)

Cheers!

Hey @Thilo-H

Do you think we missed something about the decorator pattern in this tutorial? We'll release a new design patterns tutorial soon but we'll talk about new design patterns only.
Perhaps you'll find this video helpful https://www.youtube.com/watch?v=j40kRwSm4VE

Cheers!

Hey Dang,

PHP Attributes make it easier, so some features are not available as annotations. I would recommend you to upgrade to a maintained PHP version... but for now just look for other possible configuration options: https://symfony.com/doc/current/service_container/service_decoration.html

Cheers!

Hey @Annemieke-B

I'm glad to know you like our tutorials. Your decorator it's fine, what you're missing is to add that new authenticator to the firewall

security:
    firewalls:
        main:
            custom_authenticators:
             - App\AddSupportHttpBasicAuthenticatorDecorator 
             ...

Give it a try, it should work. Cheers!

Thankyou for the quick reply.
I have made some changes and it works now, but i'm not sure if i have done it the correct way.
It's nice that it's working but i want it to be correct. So could you check?

• I've added this to my security yaml file.

  firewalls:
    ...
    main:
      custom_authenticators:
        - App\Decorator\AddSupportHttpBasicAuthenticatorDecorator
  

• I have removed AsDecorator in decorator class because i don't need it in this case, am i correct?

• I am only implementing one interface instead of two in the decorator class. So only AuthenticatorInterface and not AuthenticationEntryPointInterface because i think i don't need both, you only need one common interface between decorator class and the vendor class, correct?

• And i needed to do this in services.yml:

  App\Decorator\AddSupportHttpBasicAuthenticatorDecorator:
    arguments:
      - "@security.authenticator.http_basic_ldap.main"
  

So it works, but it has some weird behaviour. With the debugger i can see, that when enduser logs in, de support function in my decorator class is called twice and also the support function in vendor class.

Thanks in advance for helping me (again) .
Annemieke

Hey!

I have removed AsDecorator in decorator class because i don't need it in this case, am i correct?

Yes, it's not required to decorate it, if you need to reuse some of its code, you could use inheritance

I am only implementing one interface instead of two in the decorator class. So only AuthenticatorInterface and not AuthenticationEntryPointInterface because i think i don't need both, you only need one common interface between decorator class and the vendor class, correct?

Correct! The AuthenticationEntryPointInterface it's needed when you specify the "entry point" in your security.yaml file

With the debugger i can see, that when enduser logs in, de support function in my decorator class is called twice and also the support function in vendor class.

Hmm, that's a bit unexpected. Do both calls come from the same authenticator? Is something in the request triggering another request? Could you debug further and find out who's making the extra call?

Hey Andrey,

That's another PhpStorm plugin that give you such icons, it's called "Atom Material Icons". Install it if you want to the same icons style :)

And don't worry, that's not something we've talked in the course, so the valid question ;)

Cheers!

Cheers! If there are any specific patterns you'd like to see, let us know!

Hey Maxim!

Ah, cool question! The easiest way to do this is on an environment-by-environment basis. For example, to do something in the dev environment only, it would be as simple as (in services.yaml)

when@dev:
    # ... now add the decoration config

I think you can also do this with PHP attributes:

#[AsDecorator(decorates: ...)]
#[When(env: 'dev')]
class MyDecorator implements SomethingInterface
{
}

If you need to do something more complex, like via the value of an environment variable, I'm not sure if that is solvable simply with some config. It might be, but I don't know. What I would try to do is:

A) register your decorator service via services.yaml
B) But, set that decorator to be created via a factory service https://symfony.com/doc/current/service_container/factories.html
C) In that factory service, read the env var value to determine if you should instantiate the true decorator service or some "dummy"/blank decorator.

Cheers!

Design patterns through Symfony - many thanks to your team, that was like a Christmas gift for me! Please, add Adapter, Command or any other pattern, which could participate in Clean Architecture. Thank you in advance

Hey Alexander,

Thank you for your feedback! We're really happy to hear you liked the tutorial! :) We will add those additional patters to our idea pool for future tutorials. ;)

Happy new year!

Cheers!

Oh yeah, happy new year & Слава Україні!

Happy new year to you too! :) Героям слава!