What is the best method for getting a database connection/object into a function in PHP?

Question

A couple of the options are:

$connection = {my db connection/object};

function PassedIn($connection) { ... }

function PassedByReference(&$connection) {         


        

Answer 1

I use a Singleton ResourceManager class to handle stuff like DB connections and config settings through a whole app:

class ResourceManager {
    private static $DB;
    private static $Config;

    public static function get($resource, $options = false) {
        if (property_exists('ResourceManager', $resource)) {
            if (empty(self::$$resource)) {
                self::_init_resource($resource, $options);
            }
            if (!empty(self::$$resource)) {
                return self::$$resource;
            }
        }
        return null;
    }

    private static function _init_resource($resource, $options = null) {
        if ($resource == 'DB') {
            $dsn = 'mysql:host=localhost';
            $username = 'my_username';
            $password = 'p4ssw0rd';
            try {
                self::$DB = new PDO($dsn, $username, $password);
            } catch (PDOException $e) {
                echo 'Connection failed: ' . $e->getMessage();
            }
        } elseif (class_exists($resource) && property_exists('ResourceManager', $resource)) {
            self::$$resource = new $resource($options);
        }
    }
}

And then in functions / objects / where ever:

function doDBThingy() {
    $db = ResourceManager::get('DB');
    if ($db) {
        $stmt = $db->prepare('SELECT * FROM `table`');
        etc...
    }
}

I use it to store messages, error messages and warnings, as well as global variables. There's an interesting question here on when to actually use this type of class.