Example of good function construction practice

pdo_example.php

<?php

/**
 * @param string $dsn DSN string to pass the PDO object. Passed in to prevent tight coupling
 * @param string $user Username for a privileged user in the database.
 * @param string $password Password matching $user.
 *
 * @return \PDO
 */
function pdoConnect($dsn, $user, $password) {
    $pdo = new PDO($dsn, $user, $password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);

    return $pdo;
}

/* Snip */

try {
    $pdo = pdoConnect("mysql:host=localhost;dbname=database-name", "some_user", "some_password");
    $pdo->prepare("Some Query");
    //....
}
catch (PDOException $e) {
    //Error handling here
}