View source for Dependency Injection in Joomla 4

=== Creating an Object in a Container === <!--T:12-->
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<translate><!--T:13--> To place something in the Global DIC the simplest way is to pass in an anonymous function. An example for a logger is:</translate>

<syntaxhighlight lang="php">
// Assuming we have an instance of a Joomla Container
$container->share(
	LoggerInterface::class,
	function (Container $container)
	{
		return \Joomla\CMS\Log\Log::createDelegatedLogger();
	},
	true
);
</syntaxhighlight>

<translate><!--T:14--> The share function takes two mandatory parameters and an optional third parameter.</translate>
<translate><!--T:15--> * A name for the service is nearly always the class name that you're creating</translate>
<translate><!--T:16--> * An anonymous function takes a single parameter - the container instance. (This allows you to retrieve any dependencies out the container.) The return is the service that you want to place into the container</translate>
<translate><!--T:17--> * (optional) This Boolean controls whether the service is protected. (That is, whether anyone else is allowed to override it in the container.) Generally for Joomla core services, such as session objects, this is true.</translate>

<translate><!--T:18--> Let's now look at a more complicated example:</translate>

<syntaxhighlight lang="php">
$container->alias('AmazingApiRouter', Joomla\CMS\Router\ApiRouter::class)
	->share(
	\Joomla\CMS\Router\ApiRouter::class,
	function (Container $container)
	{
		return new \Joomla\CMS\Router\ApiRouter($container->get(\Joomla\CMS\Application\ApiApplication::class));
	},
	true
);
</syntaxhighlight>

<translate><!--T:19--> Here you can see we've done two extra things - we've started using dependencies (the API router gets the API application out the container) and we've also created an alias for the ApiRouter. That means if the container recognises that it needs to build an ApiRouter instance it can do that. But in our code to keep things simple we can also run ''Factory::getContainer()->get('AmazingApiRouter')'' to retrieve our router.</translate>

<translate><!--T:20--> Whilst in Joomla our providers can look more complicated than this because the logic to create objects inside the anonymous function is more complicated - all of them follow this base idea.</translate>

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