README

Description

Feature toggle is responsible for switching service injection depending on configuration.
Allowing to modify system behavior without changing code.

Example

Example use JMSDiExtraBundle, but you can easily configure it with services.yml

Let's say we want to store images. On developer machines we want to store them on file system, but anywhere else we want to store them on amazon.

interface PictureStorage
{
    /**
     * @param PictureWithContent $picture
     * @return void
     */
    public function store(string $pictureName, string $content);
}


/**
* @DI\Service("amazon_picture_storage")
* @DI\Tag(name="toggle", attributes={"for"="picture_storage", "on"="amazon_storage", "when"="enabled"})
*/
class AmazonPictureStorage
{
    public function store(string $pictureName, string $content)
    {
        // send it amazon
    }
}

/**
* @DI\Service("file_system_picture_storage")
* @DI\Tag(name="toggle", attributes={"for"="picture_storage", "on"="amazon_storage", "when"="disabled"})
*/
class FileSystemPictureStorage
{
    public function store(string $pictureName, string $content)
    {
        // save it locally
    }
}

Now when we have our services defined. We have to set default service, that will always be chosen, if all when specification fails. We are doing it by service aliases. The default for us is amazon_picture_storage

services.yml
    picture_storage:
       alias: amazon_picture_storage

We should also have the parameter, that we are using for deciding which implementation to pick.
In our example it's amazon_storage.

parameters.yml
    amazon_storage: "disabled"

We can make use of our storage now.

class AppController
{
    private $pictureStorage;

    /**
     * @DI\InjectParams({
     *      "pictureStorage" = @DI\Inject("picture_storage")
     * })
    */
    public function __construct(PictureStorage $pictureStorage)
    {
        $this->pictureStorage = $pictureStorage;       
    }

    public function createPersonWithImage(string $pictureName, string $content)
    {
        $this->pictureStorage->store($pictureName, $content);
    }
}

Annotation Explained

@DI\Tag(name="toggle", attributes={"for"="picture_storage", "on"="amazon_storage", "when"="disabled"})

• name="toggle" - Marks service to be used by FeatureToggleBundle
• "for"="picture_storage" - Which service alias will replaced
• "on"="amazon_storage" - Parameter name, that will be used for deciding, which one to inject
• "when"="disabled" - On what parameter value service containing this tag should be picked

So service that contains above tag will be used when amazon_storage parameters will be equal to "disabled"