stuartwakefield/platter

Light-touch dependency injection

Platter

Light-touch dependency injection., _(*1)

, _(*2)

Usage

To install add to your composer.json:, _(*3)

"require": {
    "stuartwakefield/platter": "0.1.0"
}

After you have run composer install you will be able to use the Platter DI manager., _(*4)

Create a new Platter instance with your definitions:, _(*5)

$factory = new Platter(array(
    'dbuser' => 'admin',
    'dbpassword' => 'password',
    'dbname' => 'test',
    'dbhost' => '0.0.0.0',
    'connectionstring' => function ($container) {
        return "mysql:dbname={$container->get('dbname')};host={$container->get('dbhost')}";
    },
    'pdo' => function ($container) {
        return new PDO(
            $container->get('connectionstring'),
            $container->get('dbuser'),
            $container->get('dbpassword')
        );
    },
    'repository' => function ($container) {
        return new Repository($container->get('pdo'));
    }
));

To retrieve an object from your container, just use the get method:, _(*6)

$repository = $factory->get('repository');

You can also link Platter containers together, one container is considered the child and the other the parent., _(*7)

$parent = new Platter(array(
    'dbuser' => 'xyz',
    'dbpassword' => 'abc'
));

$factory = new Platter(array(
    'DataSource' => function ($container) {
        return new DataSource(
            $container->get('dbuser'),
            $container->get('dbpassword')
        );
    }
), $parent);

$ds = $factory->get('DataSource');

When resolving dependencies if the child does not have a definition for the dependency the dependency will be obtained from the parent., _(*8)

Note: The direction in which dependencies are resolved is unidirectional, a parent will not check it's children for a dependency. Therefore, definitions attached to a container can only access other definitions within that container and it's parents but not it's children., _(*9)

The following will not work:, _(*10)

$parent = new Platter(array(
    'DataSource' => function ($container) {
        return new DataSource(
            $container->get('dbuser'),
            $container->get('dbpassword')
        );
    }
));

$factory = new Platter(array(
    'dbuser' => 'xyz',
    'dbpassword' => 'abc'
), $parent);

$ds = $factory->get('DataSource'); // "Identifier 'dbuser' is not defined"

This may cause confusion if not understood:, _(*11)

$parent = new Platter(array(
    'name' => 'Joe',
    'example' => function ($container) {
        return $container->get('name');
    }
));

$factory = new Platter(array(
    'name' => 'Michael'
), $parent);

echo $factory->get('name'); // "Michael"
echo $factory->get('example'); // "Joe"

The example definition does not have access to the name definition from the child and so the name definition from the parent container is returned instead., _(*12)

Builder interface

Platter also comes with a builder interface to register items using a friendly and expressive builder interface. Once built the platter is immutable., _(*13)

$builder = new Platter\Builder;
$parent = $builder
    ->register('dbuser', 'xyz')
    ->register('dbpassword', 'abc')
    ->build();

$builder = new Platter\Builder;
$factory = $builder
    ->register('DataSource', function ($container) {
        return new DataSource(
            $container->get('dbuser'),
            $container->get('dbpassword')
        );
    })
    ->connect($parent)
    ->build();

To show all available items served by the platter:, _(*14)

$factory->available(); // array('DataSource', 'dbpassword', 'dbuser');

To show the items that the platter instance itself defines:, _(*15)

$factory->defined(); // array('DataSource');

To create a singleton use the Singleton definition object:, _(*16)

$builder
    ->register('DataSource', new Platter\Definition\Singleton(function ($container) {
        return new DataSource(
            $container->get('dbuser'),
            $container->get('dbpassword')
        );
    }))
    ->build();