Function Definitions

Function declarations follow the "one true brace" convention:
function fooFunction($arg1, $arg2 = '')
{
    if (condition) {
        statement;
    }
    return $val;
}

Arguments with default values go at the end of the argument list. Always attempt to return a meaningful value from a function if one is appropriate. Here is a slightly longer example:
function connect(&$dsn, $persistent = false)
{
    if (is_array($dsn)) {
        $dsninfo = &$dsn;
    } else {
        $dsninfo = DB::parseDSN($dsn);
    }

    if (!$dsninfo || !$dsninfo['phptype']) {
        return $this->raiseError();
    }

    return true;
}