[DI] Add exclude to TaggedIterator and TaggedLocator

[ruudk]

Q	A
Branch?	6.1
Bug fix?	no
New feature?	yes
Deprecations?	no
Tickets
License	MIT
Doc PR

With this change, you can exclude one or more services from a tagged iterator
or locator.

It's common when working with Delegator or Chain services that call a list of services that
implement an interface, to also want to implement the interface on Delegator/Chain.

An example of this is in the Symfony HttpKernel component:

symfony/src/Symfony/Component/HttpKernel/CacheClearer/CacheClearerInterface.php

Lines 19 to 25 in 0d6e859

	interface CacheClearerInterface
	{
	/**
	* Clears any caches necessary.
	*/
	public function clear(string $cacheDir);
	}

symfony/src/Symfony/Component/HttpKernel/CacheClearer/ChainCacheClearer.php

Lines 21 to 31 in 0d6e859

	class ChainCacheClearer implements CacheClearerInterface
	{
	private iterable $clearers;
	/**
	* @param iterable<mixed, CacheClearerInterface> $clearers
	*/
	public function __construct(iterable $clearers = [])
	{
	$this->clearers = $clearers;
	}

The ChainCacheClearer implements CacheClearerInterface and calls a list of CacheClearerInterface
clearers.

If that would have been configured with #[AutoconfigureTag] and #[TaggedIterator], the
ChainCacheClearer would receive itself in the iterable $clearers.

With this change, it can exclude itself and rely fully on autowire/configure.

Another example:

#[AutoconfigureTag]
interface ErrorTracker
{
    public function trackError(string $error): void;
}

final class SentryErrorTracker implement ErrorTracker
{
    public function trackError(string $error): void
    {
        echo "Send error to Sentry\n";
    }
}

final class NewRelicErrorTracker implement ErrorTracker
{
    public function trackError(string $error): void
    {
        echo "Send error to NewRelic\n";
    }
}

final class DelegatingErrorTracker implements ErrorTracker
{
    public function __construct(
        #[TaggedIterator(ErrorTracker::class, exclude: self::class)]
        private iterable $trackers
    ) {}

    public function trackError(string $error): void
    {
        foreach($this->trackers as $tracker) {
            $tracker->trackError($error);
        }
    }
}

// Alias ErrorTracker interface to DelegatingErrorTracker service

final class MyController
{
    public function __construct(private ErrorTracker $errorTracker) {}
    public function __invoke()
    {
        $this->errorTracker->trackError('Hello, World!');
    }
}

Without this change, the DelegatingErrorTracker would receive itself in the tagged
iterator.

[ruudk]

The fabbot.io suggestion doesn't make any sense.

[ruudk]

@nicolas-grekas Curious what you think about this approach.

[carsonbot]

Hey!

I think @fractalzombie has recently worked with this code. Maybe they can help review this?

Cheers!

Carsonbot

[fractalzombie]

@ruudk Hi, this is the first time I've seen such use of tags, I don't quite understand the rationality of this solution.

[Jeroeny]

Should it be added to this method too DependencyInjection/Loader/Configurator/ContainerConfigurator.php#L142 ?

[ruudk]

@Jeroeny Good one, added it to the to-do. First I would like to know if this is something that could be merged. Then I can improve/finalize the PR.

[wouterj]

The fabbot.io suggestion doesn't make any sense.

Yes, you can ignore the suggestion. Fabbot tries really hard to act like a human, but sometimes they just can't hide being a robot :)

[nicolas-grekas]

Works for me, here are some notes. Thanks for submitting.

[ruudk]

@nicolas-grekas Thanks for your review, I applied your feedback and added more tests. The CI fails due to unrelated errors on 6.1 branch.

[fabpot]

Thank you @ruudk.