Creating an application #4 - the final

Part 4: The final.

The factory is useful if you need to create objects using definition syntax and/or want to configure defaults for objects created.

$container = new PSR11DependencyInjectionContainer();
$factoryConfig = [
    EngineInterface::class => [
        'class' => EngineMarkOne::class,
        '__construct()' => [
            'power' => 42,

$factory = new Factory($container, $factoryConfig);

$one = $factory->create(EngineInterface::class);
$two = $factory->create(
        'class' => EngineInterface::class,
        '__construct()' => [
           'power' => 146,

In the code above we define factory config specifying that when we need EngineInterface, an instance of EngineMarkOne will be created with power constructor argument equals to 42. We also specify that all the dependencies requested by the object created should be resolved by PSR11DependencyInjectionContainer.

First call to create() uses default configuration of EngineInterface as is. Second call specifies custom configuration for power constructor argument. In this case, configuration specified is merged with default configuration overriding its keys when the key name is the same.

The factory always create new instance. The container di create new instance once and return same on next calls.

Now that we are clear about the concepts of configuration, container di and factory, let’s see the complexity of creating an app.

composer create-project --prefer-dist --stability=dev yiisoft/app app-template

Take a look at the configuration, and you’ll see that changing it is as simple as changing a parameter in params.php, we’ve developed the right tools, that will do the job for you, that’s simplicity.

Welcome to Yii3.

In the next post we will talk about assets, view, widget, db and active-record.

Wilmer Arámbula.

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Do you know any such fast paced tutorial on REST API like this one?
If there is none, you can think of adding it… or anyone else for that matter!