How to Make Commands Lazily Loaded

The traditional way of adding commands to your application is to use add(), which expects a Command instance as an argument.

In order to lazy-load commands, you need to register an intermediate loader which will be responsible for returning Command instances:

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use App\Command\HeavyCommand;
use Symfony\Component\Console\Application;
use Symfony\Component\Console\CommandLoader\FactoryCommandLoader;

$commandLoader = new FactoryCommandLoader([
    'app:heavy' => function () { return new HeavyCommand(); },
]);

$application = new Application();
$application->setCommandLoader($commandLoader);
$application->run();

This way, the HeavyCommand instance will be created only when the app:heavy command is actually called.

This example makes use of the built-in FactoryCommandLoader class, but the setCommandLoader() method accepts any CommandLoaderInterface instance so you can use your own implementation.

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use Symfony\Component\Console\CommandLoader\FactoryCommandLoader;

$commandLoader = new FactoryCommandLoader([
    'app:foo' => function () { return new FooCommand(); },
    'app:bar' => [BarCommand::class, 'create'],
]);

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use Symfony\Component\Console\CommandLoader\ContainerCommandLoader;
use Symfony\Component\DependencyInjection\ContainerBuilder;

$containerBuilder = new ContainerBuilder();
$containerBuilder->register(FooCommand::class, FooCommand::class);
$containerBuilder->compile();

$commandLoader = new ContainerCommandLoader($containerBuilder, [
    'app:foo' => FooCommand::class,
]);