Dependency injection decorator 17/07/2017

In nette/di vendor, there is an extension called Nette\DI\Extensions\DecoratorExtension which is registered into DIC by default. What it does?

Let’s say you have many classes of one type:

interface IDataProvider
{
    public function setLocale(string $locale): void;

    public function getData(): array;
}


abstract class AbsctractDataProvider
{
    protected $locale;

    public function setLocale(string $locale): void
    {
        $this->locale = $locale;
    }
}


final class UserDataProvider extends AbsctractDataProvider implements IDataProvider
{
    public function getData(): array
    {
        return [];
    }
}


final class ProductDataProvider extends AbsctractDataProvider implements IDataProvider
{
    public function getData(): array
    {
        return [];
    }
}


final class CategoryDataProvider extends AbsctractDataProvider implements IDataProvider
{
    public function getData(): array
    {
        return [];
    }
}

Now that you have all data providers registered in config.neon:

services:
    - App\Presenters\UserDataProvider
    - App\Presenters\ProductDataProvider
    - App\Presenters\CategoryDataProvider

you would normally have to set $locale parameter for yeach service separately. Or you can use a decorator:

decorator:
    App\Presenters\IDataProvider:
        setup:
            - setLocale('cs')

All registered services implementing IDataProvider will now have a $locale parameter set. :)