Question

(N is unknown)

$controller->$action($params);

must be

$controller->$action($param1, $param2, $param3… $paramN);

Answer 1

Not really sure what you want, but if you want to call a method with an unknown number of parameters you can use call_user_func_array()

for example:

$result = call_user_func_array(array($controller, $action), $params);

which given an array like:

array(1, 2, 'a');

would be equivalent to this:

$result = $controller->$action(1, 2, 'a');

You could build such an array by doing something like below, but I think it would be better to use an array in the first place

$param1 = 'Something';
$param2 = 'Test';

$j = 1;
$params = array();
while (isset(${'param' . $j})) {
    $params[] = ${'param' . $j};
    $j++;
}

print_r($params);

//will output
Array
(
    [0] => Something
    [1] => Test
)