Service Container

This chapter’s big win is centralizing object creation with a hand-built Container so index.php and battle.php stop duplicating new PDO() setup. The Container::getPDO() method becomes the single place that knows how to build the database connection, which makes future changes much easier. It also moves the database settings into the container’s constructor, so the connection logic can use shared configuration instead of hardcoded values scattered across entry scripts.

The key implementation pattern is:

$container = new Container($configuration);
$pdo = $container->getPDO();

The one gotcha worth remembering: passing $configuration into __construct() is not enough — you must assign it to $this->configuration, or getPDO() will still see null and fail when it tries to create the connection.