Cannot modify class property from shortcode handler function

Question

I'm trying to store data from a shortcode attribute in a class property, so I can use it later in other functions. But somehow I'm always ending up with the initial value of the property. Here's a reduced example to showcase my problem:

class ScopeTestClass {
    public $my_var = null;

    function __construct() {
        // The calls to add_action() go here
        // I've omitted them for this example to avoid cluttering up the code
        add_shortcode( 'my_shortcode', array($this, 'my_shortcode_handler'));
    }

    function register_scripts() {
        wp_register_script('some_script', plugin_dir_url(__FILE__) .
            '/js/some_script.js', array('jquery'), '1.0', true);

    public function my_shortcode_handler() {
        $this->my_var = 'yeeha!';
        wp_enqueue_script('some_script');
        wp_localize_script( 'some_script', 'somescript', array(
            'ajax_url' => admin_url( 'admin-ajax.php' )));

    }

    public function ajax_handler() { 
        // This function handles the ajax call from some_script.js.
        // When evaluating $this->my_var here, it is null. 
    }
}

$test_obj = new ScopeTestClass();

While my_var is correctly set to "yeeha!" in the shortcode function, in the ajax_handler() function it shows as null. Is this an issue of scope? I thought it might be because both the shortcode and the ajax handler functions are called from outside the object context and thus $this doesn't point to test_obj, but other questions and articles I've read didn't seem to have this problem. So.. what is my issue here?

Answer 1

If you are posting from the script to the AJAX handler, that is an entirely different request, the script has no way of knowing the my_var value, so how can it be passed back to the AJAX.

But this is why you are using localize script isn't it? Why not simply pass the value in that array?

wp_localize_script( 'some_script', 'somescript', array(
        'ajax_url' => admin_url( 'admin-ajax.php' ), 
        'my_var' => $this->my_var 
    )
);