README

The reference EnvLoaderService implementation uses parse_ini_string() for environment file parsing, and loads only into $_ENV.

use EnvInterop\Impl\EnvLoader;

// loads a base required file and an optional local file,
// then checks that required variables have been loaded.
new EnvLoader()
    ->loadEnv('.env.ini')
    ->loadEnvIfExists('.env.local.ini')
    ->assertEnv([
        'PDO_DSN',
        'PDO_USERNAME',
        'PDO_PASSWORD',
    ]);

The reference implementation for EnvGetter reads from a copy of $_ENV.

use EnvInterop\Impl\Env;
use PDO;

$env = new Env();

$pdo = PDO::connect(
    $env->getEnv('PDO_DSN'),
    $env->getEnv('PDO_USERNAME'),
    $env->getEnv('PDO_PASSWORD'),
);