Pass $this to function nested in another public function of the same class

Question

I'm building a plugin using the WordPress Plugin Boilerplate by DevinVinson.

I'm adding a public shortcode function for wich I will need some resources (js and css), I want to enqueue scripts (that go in the footer) only when necessary, so I need to enqueue scripts just before the return of the shortcode.

Thanks to Fayaz answer I solved the main problem, but I still got a small one: I can't pass $this->plugin_name to shortcode function, variable I need to correctly name resources in the wp_enqueue_script function.

As the Boilerplate provide just add_action hooks in define_public_hooks function, I did use that, and nested inside it the add_shortcode hook, like this:

class My_Plugin {
   $plugin_public = new My_Plugin_Public( $this->get_plugin_name(), $this->get_version() );

   $this->loader->add_action( 'init', $plugin_public, 'my_plugin_ajax_register_shortcode' );

}

then in my-plugin-public.php file:

class My_Plugin_Public {

  public function __construct( $plugin_name, $version ) {

        $this->plugin_name = $plugin_name;
        $this->version = $version;

    }

  public function my_plugin_ajax_register_shortcode(){


     function the_actual_shortcode($atts){

        $content = 'shortcode content';

        wp_enqueue_script( $this->plugin_name.'_google_maps_api' ); // we don't know what $this->plugin_name is!

        return $content;    
     }
     add_shortcode('my_shortcode', the_actual_shortcode);
 }

}

As you can imagine, the the_actual_shortcode function, ignores $this->plugin_name, how can I pass it?

Answer 1

There are multiple ways to accomplish this. I'm showing you a way that will not fundamentally change how you are doing it:

First in My_Plugin class:

class My_Plugin {
    // ...
    private function define_public_hooks() {
        $plugin_public = new My_Plugin_Public( $this->get_plugin_name(), $this->get_version() );
        $this->loader->add_action( 'init', $plugin_public, 'init' );
        // ...
    }
    // ...
}

Then in My_Plugin_Public class, create a new method named init. Here you'll do things that you want once WordPress init action hook is triggered. So adding shortcode will go into this init method:

class My_Plugin_Public {

    public function __construct( $plugin_name, $version ) {

        $this->plugin_name = $plugin_name;
        $this->version = $version;

    }

    public function init() {
        add_shortcode( 'my_shortcode', array( $this, 'my_plugin_ajax_register_shortcode' ) );
    }

    public function my_plugin_ajax_register_shortcode( $atts ) {
        $content = 'shortcode content';
        wp_enqueue_script( $this->plugin_name . '_google_maps_api' );
        return $content;
    }
}

So, basically instead of creating an inner function within the class method my_plugin_ajax_register_shortcode, we are utilizing another method named init within the class. Now we'll be able to access $this->plugin_name inside the shortcode handler function, because now it's within the scope of our My_Plugin_Public class.