unctions shall be called with no spaces between the function name, the opening parenthesis, and the first parameter; spaces between commas and each parameter, and no space between the last parameter, the closing parenthesis, and the semicolon. Here's an example:

$var = foo($bar, $baz, $quux);

As displayed above, there should be one space on either side of an equals sign used to assign the return value of a function to a variable. In the case of a block of related assignments, more space may be inserted to promote readability:

$short		= foo($bar);
$long_variable	= foo($baz);

Function declarations follow the unix 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;
}