PHP isset not works on $this variable

Question

I am trying to figure out why isset doesn't works on $this variable? I am using HMVC codeigniter and trying to check if module loaded successfully:

$this->load->module('welcome'); var_dump(isset($this->welcome)); print_r($this->welcome);

Result is:

bool(false) --- This is the result of isset. Below is result of var_dump
Welcome Object
(
    [autoload] => Array
        (
        )

    [load] => MY_Loader Object
        (
            [_module:protected] => welcome
            [_ci_plugins] => Array
                (
                )

            [_ci_cached_vars] => Array
                (
                )

            ... some other protected variables

            [controller] => Welcome Object
 *RECURSION*
        )

)

Why isset returns false?

Answer 1

After deep checking CodeIgniter core files, I figured out there is a way to check it:

        if(!isset(Modules::$registry['welcome'])) { // check module loaded
            return jsonError(2);
        }

        // module loaded. Go ahead